산화물 나노구조물 기반 화학센서에 관한 연구

박재영 인하대학교 대학원 2010 국내박사

Recently, one-dimensional nanomaterials such as nanorod, nanofiber, nanowire, and nanotube of various metal oxide materials have attracted increasing interest, because of their fundamental scientific interest and potential applications in a variety of functional devices. These fascinating materials exhibit novel physical properties owing to their unique geometry with high aspect ratio. They are the potential building blocks for a wide range of nanoscale electronics, optoelectronics, magnetoelectronics, and sensing devices. Among the applications, sensing devices are increasingly needed for industrial health and safety, environmental monitoring, and process control. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the performance of traditional devices, such as resistive metal oxide sensors. Particularly one-dimensional nanostructrues such as nanorods, nanofibers, nanowires, and nanotubes have much larger surface-to-volume ratios compared to their thin film and bulk material counterparts, their application to miniaturized highly sensitive chemical sensors has been predicted to be promising. Nanomaterials has been tiny volume to measure change the electric conductivity. It means great variation that the changing rates of the number of conductive electron caused by the adsorption or desorption of extremely small quantities chemical species. The Electrical transport of oxide nanostructures is strongly dependent on the surface depletion layer of nanowires by adsorption and/or desorption nature of chemical species. Chemical sensors using single nanowires are very promising for fast detection and high sensitivity. Despite significant achievements in the realization of chemical sensors based on single nanostructures, there still remain many aspects that should be overcome before their actual application. First, the fabrication of gas sensors based on it usually requires an extremely careful photolithography process, with a series of fabrication steps being expensive and tedious. Second, the current change in a single 1D nanostructure during the interaction process of gaseous species on its surface is infinitesimal, consequently demanding an expensive measuring system. Third, the measured current values generally show a big variation even in the same sample due to slightly different sizes and morphologies of each 1D nanostructure as well as different natures of electrical contacts in each sensor, which means that obtaining reliable gas sensors based on a single1D nanostructure is not easy. We attempt new approaches both vertically aligned nanowire arrays and randomly networked nanowires to used multiple nanostructures chemical sensors to overcome the disadvantages of single nanostructure chemical sensor. We have focused on fabricating sensor based on vertically aligned nanowire arrays and randomly networked nanowires and investigating their sensing properties. Vertically and laterally aligned ZnO nanorod arrays with uniform distributions in their diameters, lengths, and densities were synthesized on Pt-coated Si substrates by catalyst-free metalorganic chemical vapor deposition. An approach to fabricating chemical sensors based on ZnO nanorod arrays with top-top electrode configuration using a coating- and-etching process with a photo-resist is reported. To practically test the device, its O2 and NO2 sensing properties were investigated. The gas sensing properties of this type of device suggest that the approach is promising for the fabrication of sensitive and reliable nanorod chemical sensors. ZnO, CuO, and SnO2 nanofibers were synthesized using an electrospinning method. X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy showed that the synthesized nanofibers were distributed uniformly over the Si substrates and had a polycrystalline nature. Individual nanofibers consisted of nanograins. The nanograins coalesced and grew under higher calcination temperatures and longer calcination times. The activation energy for grain growth of ZnO and SnO2 nanofibers was estimated to be 16.1 kJ/mol and 23.12 kJ/mol, respectively. The estimated m value suggests that the growth mechanism of nanograins is mainly through lattice diffusion in a pore control scheme. The sensing properties of the fabricated nanofiber sensor to NO2 and CO were systematically investigated. The sensors exhibited good sensitivity and dynamic properties for the tested gases. In particular, ZnO, CuO and SnO2 nanofibers sensor’s sensitivity was as high as over 20 at 1ppm NO2 gas, 20 at 3 ppm CO gas and 25 at 5ppm NO2 gas with those of previously reported gas sensor that were fabricated with different types of materials, respectively. TiO2-ZnO and SnO2-ZnO core-shell nanofibers were synthesized via a novel two-step process. First, TiO2 and SnO2 nanofibers as core layer were synthesized by electrospinning. In sequence, ZnO shell layers were deposited using atomic layer deposition on the electrospinning synthesized TiO2 and SnO2 nanofibers. The methodology proposed in this work is expected to be one of most suitable methods for preparing various kinds of oxide core-shell nanofibers or nanowires. In order to assess the potential applicability of the core-shell nanofibers synthesized in this study to chemical sensors, their O2 and NO2 sensing properties were investigated. Good sensitivity and dynamic repeatability were observed for the sensor, demonstrating that the core-shell nanofibers hold promise for the realization of sensitive and reliable chemical sensors. Based on a selective growth of nanowires by the vapor-liquid-solid method, networked SnO2 nanowire sensors have been fabricated. Then, their sensing properties to NO2 were systematically investigated. The number of junctions was controlled by changing the spacing of the patterned-interdigital electrodes (PIEs), on which SnO2 nanowires selectively grew and touched the nanowires grown on neighboring PIEs, eventually producing junctions. The sensing mechanism is attributed to the change not only in the width of space charge region along the length direction of each nanowires, and also in the height of potential barrier at the junction during adsorption or desorption of gaseous species. Importantly, as the spacing of PIEs decrease, the number of junctions increases, eventually leading to superior sensing properties to NO2 In the present thesis, we focused on attempt the various approaches such as vertically aligned nanowire arrays and randomly networked nanowires leading to the participation of multiple nanowire in gas sensing process to overcome the shortcomings of single nanostructures chemical gas sensor. Good sensitivity and dynamic repeatability were observed for the present sensor, demonstrating that the multiple nanowires hold promise for the realization of sensitive and reliable chemical sensors.

온라인 쇼핑몰 上의 市場細分化 接近方向에 關한 硏究 : 探索道具 類型을 中心으로

朴裁永 國民大學校 大學院 2001 국내석사

터널 내 차로변경 허용 및 변속차로 설치방안에 관한 연구

박재영 서울시립대학교 2011 국내석사

When designing highways, interchanges and tunnels will occur if the neighbor. Because of lack of distance between Interchanges and tunnels, routes are designed to be unreasonable as detour routes. The purpose of this study to investigate accidents and lane-changing rate is to perform for lane changing is allowed to apply engineering judgments. Accidents rate in tunnel was lower than that of the road accidents rate. Tunnel and the road lane changing rate to about 20% was very little difference. Speed-change lane installation type is three kinds of acceleration lane and three kinds of decelerating lane. This studies of lane-changing permission and method of speed-change lane installation in tunnel has significance as basic research. 고속도로 노선 설계 시 불가피하게 출입시설과 터널이 인접하는 경우가 발생 할 경우 출입시설과 터널 간 이격거리가 부족한 상황을 극복하고자 노선우회와 같은 불합리한 노선 설계가 이루어지고 있다. 이러한 원인은 터널 내 차로변경이 허용되지 않기 때문이다. 본 연구의 목적은 터널 내 차로변경을 허용하기 위해 사고자료를 통해 사고율을 분석하고, 차로변경율 조사를 수행하여 차로변경의 허용 근거를 마련하고, 터널 내 환경 및 차량의 암도 특성을 고려하여 반응지연시간의 가중치를 적용한 설계요소 및 변속차로 설치 유형 도출하는 것이다. 터널 내 변속차로 설치를 위한 선결조건인 차로변경을 허용하기 위한 근거 마련을 위해 2005~2009년간 고속도로 터널 및 일반구간의 사고자료를 통해 사고율을 분석하였다. 국내 터널구간의 사고율은 0.02건/백만차량-km로 일반구간 0.04건/백만차량-km으로 터널의 사고율이 낮았으며, 차로변경횟수를 조사하여 터널과 일반구간의 차로변경율은 각각 23%, 24%로 거의 비슷한 비율로 차로변경이 행해지고 있음을 도출하였다. 변속차로의 설계요소를 정의하고 설치 유형을 가속차로 3개, 감속차로 3개의 유형을 설정하였으며, 터널 내 변속차로 설치방안은 기하구조 및 시설을 고려한 방안을 제시하였다. 본 연구는 장대터널이나 지하고속도로와 같은 구조 내부에서 차로변경 및 변속차로 설치를 가늠할 수 있는 기초연구로써 의의를 가진다.

미생물농약과 기타방제제의 혼용에 의한 오이 흰가루병방제

박재영 순천대학교대학원 2014 국내석사

Fifteen biofungicides were registered but thirteen biofungicides commercially distributed and utilized in Korea. All of them have higher active microorganisms than concentrations labeled on the registered commercial products. Among them,seven biofungicides registered as control agents for powdery mildew of cucumber did not induce any phytotoxicity on cucumber plants. Control efficacies of the biofungicides against powdεry mildew wεre quite different according to thε kinds of biofungicides but those of the biofungicides increased with the numbers of spray on cucumber plants. Control efficaciεs of thε biofungicidεs also increased by mixing application or altεrnative application of two biofungicides. Control εfficaciεs of thε biofungicidε Bαcillus subtilis KB-40 1 against powdεry mildew of cucumber werε not significantly different with those of Bordeaux mixture and Fernarimol EC. Control efficacies of the biofungicide Bacillus subtilis KB-401 against powdery mildew of cucumbεr increased by mixing application or altεrnative application with Bordeaux mixture or cooking oil and york mixture. Mixing application or alternative application of the biofungicide and chemical fungicide which effectivεIy controlled powdery mildew of cucumber could be proposεd as one of the control stratεgy to rεduce thε amount of chεmical fungicidεs.

운영 중인 터널의 노면 융기 보강 방법에 관한 수치해석

박재영 청주대학교 대학원 2025 국내박사

본 연구에서는 운영 중인 터널에서 지반 열화 및 소성압에 의한 노면 융기 발생 구간에 보강재 설치를 통한 융기 억제 효과를 파악하기 위하여 소성 영역 규모, 보강재 형식별 수치해석을 통해 보강 효과를 비교 검토하였다. 소성영역 규모는 터널 노면으로부터 터널 폭의 2배에 해당하는 약 20 m 심도까지 수평 소성 영역대를 가정하였으며, 보강공법으로는 인버트 공법과 마이크로파일 공법을 검토하였다. 이때, 인버트 공법은 부재 강성을 고려한 부재 규격, 종방향 설치 간격에 대하여 검토하였으며, 마이크로파일 공법은 보강 본 수, 보강 길이, 종방향 보강 간격, 보강 각도에 대해 검토하였다. 검토 결과 소성영역 내 지반 열화에 의한 지반 강도 감소 시 노면 융기 대책으로 인버트 보강이 가장 효과적이며, 부재의 규격보다는 종방향 설치 간격이 보강효과에 영향이 큰 것으로 확인되었다. 마이크로파일은 보강 본 수 및 보강 길이, 종방향 보강 간격이 노면 융기 억제에 영향을 미치는 것으로 확인되었다. 소성영역 발생 구간에 대한 보강재로는 터널 노면 하부에 인버트 공법이 주로 사용되어 왔으나, 운영 중인 터널구간에서는 원활한 도로 기능 유지와 조속한 시공 등을 고려할 때, 마이크로파일 공법의 적용성이 대안 공법으로 효과적인 것으로 판단된다. In this study, numerical analyses were conducted to compare and evaluate the reinforcement effects of different reinforcement types and plastic zone sizes in mitigating surface uplift caused by ground deterioration and plastic pressure in an operating tunnel. A horizontal plastic zone was assumed to extend from the tunnel surface to a depth of approximately 20 meters, corresponding to twice the tunnel width. The invert and micropile methods were considered as reinforcement measures. In the case of the invert method, member specifications incorporating structural stiffness and longitudinal installation spacing were analyzed. For the micropile method, the analysis focused on the number of reinforcement elements, lengths, longitudinal spacing, and installation angles. The analysis results indicated that, in cases of ground strength reduction due to ground deterioration within the plastic zone, the invert method was the most effective countermeasure for mitigating surface uplift. It was also found that the longitudinal installation spacing had a greater influence on reinforcement effectiveness than the member specifications. In the case of micropiles, the number of reinforcement elements, reinforcement length, and longitudinal spacing were identified as important factors affecting the suppression of surface uplift. As a reinforcement material for the section where the plastic zone occurs, invert application to the lower part of the tunnel road surface has been mainly used. However, considering the maintenance of road function and speedy construction in the operating tunnel, the applicability of micropiles is considered to be an effective alternative method.

지역적 특성을 반영한 거시적 교통사고 분석모형 개발

박재영 서울시립대학교 일반대학원 2011 국내석사

자치단체에서 담당하고 있는 지역단위의 안전정책의 수립 및 시행은 국가 전체적인 교통안전정책 사업의 수립 및 시행에 가장 핵심적인 역할을 하고 있다. 하지만 국가 및 지자체에서 실시하는 교통사고 분석의 경우 사고 잦은 지점 또는 위험지구 선정 등 국지적 측면의 분석에 치우쳐 있으며, 이러한 미시적 관점의 분석을 통해서는 자치단체 중심의 교통안전 계획의 수립 및 평가에 어려움이 있다. 지자체 중심의 안전대책의 수립 및 시행을 위해서는 기존의 1차적 요인만을 통한 미시적인 분석이 아닌 사회전체의 여건 및 특성을 반영한 거시적인 사고분석 모형의 개발이 필요하다고 할 수 있겠다. 본 연구에서는 전국 226개의 기초자치단체를 대상으로 해당 지역의 특성을 나타낼 수 있는 지표를 수집하고, 교통사고와 관련이 있을 것으로 판단되는 지표를 선정하여 사망사고 발생의 지역적 특성에 대하여 알아보고자 하였다. 분석결과 절단 음이항 모형이 가장 적합한 모형으로 선정되었으며, 총 10개의 독립변수 중 유류 판매량, 교통사고관련 투자비용, 외국인 인구, 도로연장, 고속도로 구성비, 내부통행량, 여성운전자 비율이 사망사고의 발생과 상관관계가 있는 것으로 나타났다. 연구결과 현재 국내에 구축되어 있는 통계자료를 이용하여 모형을 발전시키는 데에는 어려움이 있을 것으로 판단되며, 향후 보다 발전된 연구를 위해서는 새로운 지표의 수집과 함께 횡단면자료와 시계열자료를 함께 분석할 수 있는 패널 분석을 통한 연구를 고려해 보아야 한다. The establishment & enforcement of local level safety policy, of which autonomous communities take charge, is playing the most essential role in the establishment & enforcement of a national level traffic safety policy program. However, in case of the analysis of traffic accidents made by the nation and local autonomous entities, it is too much concentrated on the analysis of regional aspects, such as black spots or dangerous zones, so there remain a difficulty with the establishment & assessment of autonomous- community-centered traffic safety planning with such a microscopic analysis. For the establishment & enforcement of local-autonomous-entity -centered safety measures, there needs to be a macroscopic accident analysis model development reflecting the conditions & nature of the whole society other than microscopic analysis through the existing primary factors. Thus, this research is aimed at looking into the regional characteristics of fatal accident spots by collecting the indicator that can representing the characteristic of the proper district targeting 226 local governments in the nation, and selecting the indicator that is judged to have something to do with traffic accidents. As the result of analysis, the truncated negative binomial model was selected as the most suitable one, and among the total of independent variables, sales volume of oil, investment costs related to traffic accidents, foreign population, road extension, the component of highways, internal traffic volume, and ratio of women drivers were found to have correlation with the occurrence of fatal accidents. As a result of this research, it is judged that there might be a difficulty in developing a model using the currently established statistical data; thus, for more developed research later, it is necessary to consider the research pattern through panel analysis that makes it possible to make a simultaneous analysis of cross-section data and time-series data together with the collection of new indicators. Keywords : Traffic Accident Analysis Model, Regional Characteristics of Fatal Accident, Macroscopic Traffic Accident Analysis, Truncated Negative Binomial Model, Truncated Poisson Model.

멀티캐스트 전송의 신뢰성을 위한 FEC기반 오류제어 메카니즘

박재영 충북대학교 대학원 2000 국내석사

서비스품질에 의한 관계형성이 고객 충성도에 미치는 영향 : 탈모시장 서비스품질을 중심으로

박재영 건국대학교 대학원 2012 국내박사

This study investigated the effects of service quality factors on customer satisfaction and customer trust, and subsequently their mediating effect on customer loyalty. The study explored the relationships among the variables by examining the effect of service quality, categorized into three dimensions of interaction quality, perceived brand quality, and perceived quality, on customer satisfaction and customer trust, and their effect on customer loyalty as a mediating variable. Statistical analyses were conducted for the study on the hair loss market in Korea. In accordance with previous studies, three elements of service quality dimensions were adopted as an exogenous variable. The present study attempted to extend the previous research by testing not only the direct effect of the exogenous variable on the endogenous variables of customer satisfaction, customer trust, and customer loyalty but also the degree of the effect of customer satisfaction and customer trust on customer loyalty as a mediating variable. The purposes of the study were as follows: 1) to investigate the effect of the three dimensions on customer satisfaction and customer trust, employing Structural Equation Model (SEM) after categorizing the service quality into three dimensions of interaction quality, perceived brand quality, and perceived quality, and testing their reliability and validity; 2) to examine the effect of customer satisfaction on customer loyalty; 3) to look into the effect of customer satisfaction and customer trust on customer loyalty; 4) to explore the direct effect of the three service quality dimensions on customer loyalty; and 5) to investigate the mediating effect between the three service quality dimensions and customer loyalty. The study employed SEM to define structural model and measurement model, through which the research hypotheses were tested using the relational structure among the three service quality dimensions, customer satisfaction and trust, and customer loyalty in the hair loss market. Before conducting the empirical research, first, previous studies and literature were reviewed, based on which the research design and hypotheses were generated to test the relationships between service quality dimensions and other factors. Data were collected using questionnaires with hair loss customers. Confirmatory factor analysis was conducted to guarantee the validity and reliability of variable. The reliability and validity of measurement variables were tested with Chronbach's α reliability test, KMO test, and Bartlett's test of sphericity, Varimax rotation for major factor analysis, correlation analysis, and path analysis through measurement model and structure model of SEM, testing the reliability and validity of the SEM research model. To analyze the data SEM was used with AMOS 7.0 statistical package and SPSS 17.0 . The results of the study based on the path analysis of SEM are summarized below. 1. Effects of service quality dimensions on relationship building (customer satisfaction and customer trust) Hypothesis 1-1 was not supported by the data that showed interaction quality did not affect consumer satisfaction, different from Cronin and Taylor(1992) that considered service quality as a prerequisite for consumer satisfaction. Hypothesis 1-2 was also rejected, not corresponding with the results of Doney and Cannon (1997), which showed a significant effect of interaction quality on consumer trust. Hypothesis 2-1 about the effect of service quality on consumer satisfaction was not supported by the data, which was not in line with Brady and Cronin (2001). Hypothesis 2-2 was supported, showing the perceived quality had a positive effect on consumer trust. In addition, Hypotheses 3-1 and Hypothesis 3-2 were also supported, indicating the higher perceived brand quality is, the more consumer trust increases as maintained by Brady and Cronin(2001). 2. Relationship between customer satisfaction and customer trust Hypothesis 4 was supported, ascertaining that consumer satisfaction affected consumer trust. The results were in line with those from Geyskens et al. (1999) indicating direct causal relationship between consumer satisfaction and consumer trust. 3. Effects of service quality dimensions and relationship building on customer loyalty Hypothesis 5, regarding the effect of consumer satisfaction on consumer loyalty, was not supported, and this is different from Sirdeshmukh et al.(2002) did not support their claim that consumer satisfaction affects the consumer's post purchase attitude or repurchase intention. However Hypothesis 6 was suppoted. And Hypothesis 7 or Hypothesis 8, which predicted the effect of interaction quality and perceived quality on customer loyalty, was not supported by the data. The results were did not accord with those of Brady and Cronin (2001). Hypothesis 9 was supported, revealing that the perceived brand quality with a great positive service effect after hair loss service had a positive influence on customer loyalty. The results of the study suggest the following implications. First, regarding the relationship between service quality dimension and relationship building (customer satisfaction and customer trust), the perceived quality of hair loss shops was shown to affect customer trust. The finding supports that the perceived quality of hair loss stores, e.g., the interior design or brand new facilities, is more effective than interaction quality. e.g., activation of situational communication with customers, for consumer satisfaction than for consumer trust. Moreover, regarding hair loss care service, consumer satisfaction and consumer trust can be achieved through a short waiting or treatment time or post treatment experience that exceeds expectation. Second, it was found that as to the effect of establishing consumer satisfaction and consumer trust, consumer satisfaction with interaction and treatment in post treatment service process did not lead the customer's perception to consumer trust in treatment service. The results imply that even though customers are satisfied with high perceived quality at a hair loss shop, e.g., service provider's expertise, the interior design of the shop, etc., their satisfaction will lead to consumer trust. Third, regarding the effect of service quality dimensions and relationship building and customer loyalty, the study found that interaction with service providers or the perceived quality of a hair loss shop did not directly affect customer loyalty. The results suggest that perceived quality can form customer trust, it result in customer loyalty. It affects customer loyalty only through forming consumer satisfaction. The present study showed that the three service quality dimensions of the hair loss treatment service in the market should be an important marketing strategy in that they affect customer loyalty not only directly, but also indirectly through customer satisfaction and trust, showing a mediating effect. The study has a limitation in that probability sampling was not employed. 본 연구에서는 서비스 품질의 각 차원을 상호작용품질, 지각된 품질, 지각된 브랜드품질로 구분하고 서비스 품질이 고객 만족도와 고객 신뢰도에 영향을 미치는 효과와 고객 만족도와 고객 신뢰도가 고객 충성도에 미치는 매개 효과를 통해 요소 간의 상관관계를 알아보고자 하였다. 이를 위한 분석도구로 탈모시장을 통계적 분석에 이용하였으며 선행연구 결과를 참조하여 독립변수개념으로는 서비스 품질차원의 세 가지 요소를 채택하고 설정된 독립변수가 매개변수인 고객 만족도와 고객 신뢰도 그리고 고객 충성도에 미치는 직접효과뿐만 아니라 고객 만족도와 고객 신뢰도가 고객 충성도에 미치는 정도에 대한 매개 효과에 대해서도 검증함으로써 선행연구와 대비하여 차별화된 분석을 수행하고자 하였다. 본 연구를 분석하기 위한 방법론으로는 구조방정식 모형을 이용하여 구조모형 및 측정모형을 알아보고 이를 통해 탈모 시장의 세 가지 서비스 품질차원과 고객 만족도 및 고객 신뢰도, 그리고 고객 충성도 사이의 관계모형을 이용해서 영향에 관한 가설 검증을 수행하였다. 가설검증을 위해 탈모관리 고객을 대상으로 설문조사를 시행하여 측정변수에 대한 Chronbach's α 신뢰성 검증, 타당도 검증을 위해 KMO 검증과 Bartlette 구형성 검정, Varimax 회전에 의한 주성분 요인분석, 상관관계분석, 구조방정식의 측정모형 및 구조모형을 통한 경로분석, 그리고 구조방정식 연구모형의 타당성 및 적합도 검증 등을 수행하였다. 본 연구에서 구조방정식의 경로별 인과관계 분석에 의한 가설검증의 연구결과를 정리하면 다음과 같다. 첫째, 서비스 품질차원과 관계형성(고객 만족도 및 고객 신뢰도)의 관계는 다음과 같다. 가설 [H1-1]은 상호작용품질이 고객 만족도에 영향을 미치지 못하는 것으로 나타나 서비스 품질차원이 고객 만족도의 선행변수라고 보는 Cronin and Taylor(1992)의 견해와 일치되지 않은 결과를 알 수 있었다. 가설 [H1-2] 또한 기각 되어 상호작용품질이 고객 신뢰도에 영향을 미친다는 Doney and Cannon(1997)의 연구결과와 일치하지 않는 것으로 나타났다. 가설 [H2-1]은 지각된 품질이 고객 만족도에 영향을 미친다는 것이 기각되었으며, Brady and Cronin(2001)의 주장과는 상반된 결과이다. 가설 [H2-2]는 채택되어 지각된 품질이 고객 신뢰도에 정의 영향을 미치는 것으로 나타났으며 가설 [H3-1]과 가설 [H3-2] 또한 채택되어 Brady and Cronin(2001)의 주장처럼 높은 지각된 브랜드품질일수록 고객 만족도와 고객 신뢰도가 증가함을 알 수 있었다. 둘째, 고객 만족도 및 고객 신뢰도의 관계형성 관계는 다음과 같다. 가설 [H4]는 서비스품질에 대한 고객 만족도가 고객 신뢰도에 정의 영향을 미치는 것으로 나타나 채택되었으며, 이는 Geyskens et al.(1999)의 연구결과와 일치한다. 셋째, 서비스 품질차원 및 관계형성의 고객 충성도 관계에 대한 가설은 다음과 같다. 서비스품질에 대한 고객 만족도가 고객 충성도에 정의 영향을 미친다는 가설 [H5]는 기각되었으며, 이는 고객 만족도가 고객의 구매 후 태도나 재구매 의도에 영향을 미친다고 주장한 Sirdeshmukh et al.(2002)의 연구결과와 일치하지 않는다. 한편, 서비스품질에 대한 고객신뢰도는 고객 충성도에 정의 영향을 미친다는 가설 [H6] 채택되었으며 가설 [H7]과 [H8]은 상호관계품질과 지각된 품질이 고객충성도에 영향을 미친다는 것에 기각되어 Brady and Cronin(2001)의 주장과 일치하지 않음을 알 수 있었다. 가설 [H9]는 채택되어 탈모 서비스를 제공받은 후 큰 효과를 경험한 지각된 브랜드품질은 고객 충성도에 정의 영향을 미치는 것으로 나타났다. 본 연구결과는 다음과 같은 시사점을 가진다. 첫째, 탈모서비스 매장에 대해 브랜드 이미지 및 위치, 설비 등에 대해 기대 이상의 효과를 경험함으로써 지각된 브랜드품질은 고객 만족도와 고객 신뢰도를 형성한다는 사실을 발견할 수 있었다. 둘째, 탈모서비스 매장의 탈모서비스 제공자의 관리 서비스 후에 고객 인식 형성에 있어 상호작용이나 시술에 대한 탈모서비스 관리에 대한 고객 만족도와 고객 신뢰도에 영향을 미치지 않는다는 사실을 발견할 수 있었다. 또한 탈모서비스 매장의 서비스와 제품, 인테리어 디자인과 같은 고품질의 지각된 품질을 통한 고객 만족도는 형성되지 않았으며 반면에 고객 신뢰도는 영향을 미친다는 것을 알 수 있었다. 셋째, 서비스 품질차원 및 관계형성의 고객 충성도 관계로부터 종업원과의 상호작용품질과 지각된 품질은 영향을 미치지 않았고 탈모서비스 매장의 지각된 브랜드품질이 직접적으로 고객충성도에 영향을 미친다는 사실을 알 수 있었다. 또한 지각된 품질에 대한 고객 신뢰도가 형성되어 고객 충성도에 영향을 미친다는 사실을 발견할 수 있었다. 다만 고객 만족도에는 영향을 미치지 않았지만 고객 만족도에서 고객 신뢰도는 형성되었으며 고객 신뢰도에서 고객 충성도에도 영향을 미치게 된다는 사실을 발견할 수 있었다. 소비자 마케팅의 주요 전략 중 하나로서 고객 충성도에 직접적인 영향을 미칠 뿐만 아니라 고객 만족도 및 고객 신뢰도를 통한 간접적인 매개효과를 미친다는 것이다. 본 연구에서는 지각된 품질과 지각된 브랜드품질에 세심한 주의를 기울여야 한다. 소비자 마케팅 포지션의 주요 전략 중 하나로서 고객의 충성도에 직접적인 영향을 미칠 뿐만 아니라 고객 만족도 및 고객 신뢰도를 통한 간접적인 매개 효과를 미치는 것으로 나타났다. 이 와같은 연구결과를 도출하기 위한 연구의 진행과정에서 나타난 제약 및 한계점은 연구 과정에서 서비스품질의 세 가지 차원을 검증하기 위해 확률표본추출을 수행하지 못한 것을 본 연구의 한계점으로 들 수 있다.

Vibrio metschnikovii 균주로부터 분비되는 새로운 알칼리성 세린계열 단백질분해효소의 정제 및 특성 연구

박재영 조선대학교 일반대학원 2010 국내석사

해양성 박테리아인 Vibrio metschnikovii (V. metschnikovii )는 상처를 통해 침투하여 폐렴, 궤양 및 설사 등의 심각한 증상을 유발하는 것으로 알려져 있다. 본 연구에서는, V. metschnikovii ATCC700040 균주의 배양상층액으로부터 새로운 알칼리성 세린계열 단백질분해효소를 분리․정제 하였으며, 그 생화학적 특성 및 인간혈액응고단백질들에 미치는 영향을 연구하였다. 이 균주를 3% NaCl이 포함된 pH 7.5의 LB배지에서 배양하였을때, 최대의 단백질분해활성이 나타는 것을 확인하였다. 새로운 단백질분해효소를 분리하기 위하여, 모든 세포외단백질들을 70%의 황산암모늄 [(NH4)2SO4] 처리과정을 통해 침전시켰고, 이 단백질들을 Hiprep 16/10 Q FF, Source 15 Q 4.6/100 PE 및 Superdex 75 10/300 GL 컬럼크로마토그래피를 순차적으로 사용하여 단백질분해효소를 분리하였다. 순리 분리한 이 효소는 Vm-AP (V. metschnikovii alkaline protease)라 명명하였다. Vm-AP는 SDS-PAGE의 열처리 과정에서 분해되었는데, 이러한 분해는 CuCl2, ZnCl2 및 NiCl2를 첨가함으로써 억제할 수 있었다. 이 효소는 단일 폴리펩타이드로 구성되어 있었으며, CuCl2가 존재하는 환원상태 하에서 50 kDa, 비환원상태 하에서 40 kDa이 분자량을 지님을 12% SDS- 폴리아크릴아미드 겔 상에서 확인하였다. 발색성기질을 이용한 실험에서, 트롬빈의 대표적인 기질로 알려진 Boc-VPR-pNA가 이 효소에 대해 가장 특이적인 것으로 확인하였다. 이 기질을 이용하여 Vm-AP의 KM, kcat 및 kcat/KM 값이 각각 0.91 mM, 0.8 s-1 와 0.88 mM-1s-1임을 확인하였다. Vm-AP의 효소활성에 대한 최적온도와 pH는 각각 37℃ 와 pH 9.5이었으며, pH 8.0~12.0인 알칼리 환경에서 상대적으로 강한 활성을 나타내는 것으로 보아 이 효소가 알칼리성 단백질분해효소라는 사실을 알 수 있었다. 세린단백질 분해효소의 억제제로 알려진 PMSF와 aprotinin를 첨가하였을 때, 약 81.1%의 Vm-AP 활성이 감소하였는데, 이러한 결과는 본 효소가 세린계열 단백질 분해효소라는 사실을 나타낸다. Vm-AP 효소는 플라스미노겐, 플라스민, 프로트롬빈 및 트롬빈과 같은 다수의 혈액응고단백질들을 절단하였으며, 또한 강력한 피브리노겐 절단활성을 보였다. 이 효소는 γ-사슬을 포함한 피브리노겐의 모든 폴리펩타이드 사슬을 분해하였고, 피브린 중합체 및 교차-연결된 피브린까지도 분해하는 것을 확인하였다. 이러한 모든 결과를 종합하여, 병원성 균주인 V. metschnikovii는 감염 시 Vm-AP를 분비하여 혈액응고시스템을 교란시킬 가능성을 시사하는 것이다. The marine bacterium Vibrio metschnikovii (V. metschnikovii ) evokes serious symptoms, including pneumonia, leg ulcer, and diarrheal disease when it infects a wound. In this study, a novel extracellular alkaline serine protease was purified from culture supernatant of V. metschnikovii ATCC700040 and its biochemical features and effects on human blood coagulation-associated proteins were investigated. The maximal protease activity could be obtained when the bacterium was cultured in LB medium (pH 7.5) containing 3% NaCl at 30℃. To purify a proteolytic enzyme, total extracellular proteins from V. metschnikovii cells cultivated in LB medium containing 3% NaCl at 30℃ were precipitated by the addition of 70% ammonium sulfate [(NH4)2SO4]. The precipitated proteins were applied onto Hiprep 16/10 Q FF, Source 15 Q 4.6/100 PE, and Superdex 75 10/300 GL columns in order, and Vm-AP (stands for V. metschnikovii alkaline protease) could be purified at the final purification step with near homogeneity. The purified Vm-AP seemed to be degraded by the heating step for SDS-PAGE. However, the degradation could be inhibited by the addition of divalent cations such as CuCl2, ZnCl2, and NiCl2. Vm-AP was composed of a single polypeptide and its apparent molecular weight was found to be approximately 50 kDa under reducing condition in the presence of CuCl2 and about 40 kDa under non-reducing condition on 12% SDS-polyacrylamide gel. Among synthetic chromogenic substrates tested, Boc-VPR-pNA that is known as a typical chromogenic substrate for thrombin was the most favorable one for the enzyme. When the chromogenic substrate was used as a substrate, kinetic values for Vm-AP were as follows: KM = 0.91 mM, kcat = 0.8 s-1, and kcat/KM = 0.88 mM-1s-1. The optimal temperature and the pH for Vm-AP enzyme activity were 37℃ and pH 9.5, respectively. In addition, the maximal protease activity could be found under alkalic condition ranging from pH 8.0 to 12.0, suggesting that Vm-AP can be included in alkaline protease family. Approximately 81.1% of Vm-AP activity could be inhibited by the addition of serine protease inhibitors such as PMSF and aprotinin. These results suggest that Vm-AP is a member of serine protease. Vm-AP could cleave various blood coagulation-associated proteins, including plasminogen, plasmin, prothrombin, and thrombin. In addition, the enzyme showed a powerful fibrin(ogen)olytic activity, as it could cleave all kinds of chains of fibrinogen, even with γ-chain of fibrinogen, fibrin polymer, and cross-linked fibrin. Taken together, the results obtained by the present study suggest that the pathogenic bacterium V. metschnikovii might disturb the blood coagulation system by secreting an alkaline Vm-AP protease during the course of bacterial infection.

Ecological and phylogenetic studies of epiphytic fungi on the needles of pine trees in Korea

박재영 서울대학교 대학원 2007 국내박사