신경분화과정에서 Go와 Rit의 역활 규명

김승현 경기대학교 2006 국내석사

Heterotrimeric GTP binding proteins (G proteins) transduce signals initiated by a variety of hormones and neurotransmitters. Among G proteins, Go is one of the most abundant G proteins expressed in the brain and is classified as a member of the Gi/Go family due to its sequence homology to Gi proteins. To determine the function of the alpha subunit of Go in brain, We searched for Goα-interacting partners from human fetal cDNA library using yeast two hybrid screening. We identified a cDNA encoding 219 amino acids of Ras like protein in all tissue (Rit). We confirmed Goα::Rit interaction employing several biochemical analysis. Rit also preferentially bind the GoαQ205L, constitutively active form of Goα than wild type Goα. To determine the effects of Goα::Rit interaction on neuronal differentiation, we transfected expression vector for Goα or/and RitDN, dominant negative form of Rit. While the expression of GoαQ205L alone induced neurite outgrowth, coexpression of GoαQ205L and RitDN did not show such effect. To investigate the downstream signaling of Rit in neuronal differentiation, we search Ral-stat3 and ERK pathway. As results, Rit could not activate Ral-stat3 pathway and rather stimulated ERK phosphorylation. ERK phospholyrlation was increased by expression of GoαQ205L but decreased by coexpression of GoαQ205L and RitDN. These results suggested that activation of Goα increase the function by Rit as a ERK-dependent neuronal differentiation inducer.

소셜네트워크 공간빅데이터를 이용한 활동기반 교통모형 분석자료 구축에 관한 연구

김승현 서울시립대학교 2015 국내석사

오늘날 인터넷 사용의 급격한 증가, 스마트폰 보급, SNS(Social Networking Service) 활성화 등과 같은 디지털 기술의 발전과 모바일 기기의 보급 등으로 인해 우리 주변에는 규모를 가늠할 수 없을 정도로 많은 정보와 데이터가 생산되는 ‘빅데이터(Big Data)’의 시대가 도래 했으며, 그 중요성이 날로 커지고 있다. 교통분야에서는 오랜시간동안 우세를 점하고 있었고 도시교통개발에 효과적인 추정 방법으로 여겨졌던 전통적인 통행기반교통모형(Trip-Based Model)인 4단계 교통수요추정법의 한계가 드러나고 있으며, 최근의 컴퓨터 기술의 빠른 성장에 힘입어 활동기반교통모형(Activity-Based Model)을 이용한 수요 추정 방법이 교통계획에 새로운 패러다임으로 떠오르고 있으며, 연구가 활발히 진행되고 있다. 교통은 사람이나 물류의 공간상의 시간적 이동을 의미한다고 봤을 때 공간데이터와 밀접한 관련이 있으며, 최근 급부상하고 있는 공간빅데이터(Spatial Big Data)와 접목될 수 있는 분야이다. 따라서 소셜네트워크 서비스(SNS)상의 공간빅데이터를 추출해 현재 사용되고 있는 통행기반교통모형(Trip-Based Model)의 특성과 비교․분석하고 나아가 활동기반교통모형(Activity-Based Model)의 분석자료를 구축하여 공간빅데이터와 활동기반교통모형을 접목시킨다면 매우 큰 가치가 있을 것으로 생각된다. 따라서, 공간정보를 포함하고 있는 SNS를 대상으로 시계열적 공간정보를 추출하고, 이를 현재 사용되고 있는 통행기반교통모형(Trip-Based Model)의 OD와 비교․분석하여 그 특성을 파악하고, 활동기반교통모형(Activity-Based Model)의 분석자료를 구축하여 교통시뮬레이션 프로그램을 이용해 시뮬레이션을 수행하였다. 연구결과 제도적 제약에도 불구하고 다수의 활동기반 교통모형 분석자료를 구축할 수 있었고, 교통수요추정 시뮬레이터인 MATSim을 성공적으로 실행할 수 있었다. 이번 연구로 인해 교통분야에 있어 빅데이터 활용의 기술적 한계를 극복할 수 있는 가능성을 확인하였고, 향후 발전방향을 모색하는 기회가 되었다. The era of Big Data has come with the internet and the development of digital technologies, such as smart phones and social networking services(SNS). Also, the importance of Big Data has been rapidly growing. The Four-Step Travel Demand Model(FSTDM), a traditional Trip-Based Model(TBM) for effective urban transportation development in the field of transportation planning, reaches its limit. In recent years, a traffic demand forecasting method using the Activity-Based Model(ABM) emerged as a new paradigm with the rapid growth of new computer technologies. As a result, many researchers are studying on it. Given that transportation means the spatial movement of people and goods in a certain period of time, transportation could be very closely associated with spatial data. Thus, if transportation planning can be linked to Spatial Big Data, which has grown rapidly in these days, that would be very valuable data. In order to connect these two, first, I mined Spatial Big Data from SNS, such as Twitter. Next, I analyzed these data and the attributes of TBM to test the reliability of the data from SNS. After that, I built a database from SNS to manipulate an ABM simulator. During the research, there were institutional constraints on policies, such as the application programming interface limit policy. However, through this research, I was successfully able to create a spatial database from SNS to control an ABM simulator, Multi-Agent Transport Simulation(MATSim). Through this research, I found possibilities to overcome technical limitations on using Spatial Big Data in the transportation planning process, and it was an opportunity to seek ways of further research development.

하둡에서 태그를 이용한 빅데이터의 동적 분류에 관한 연구

김승현 순천대학교 대학원 2016 국내석사

In last years, Hadoop has become a basic data processing infrastructure in the field of Big data processing. Due to design limitations of Hadoop, it is difficult to efficiently classify for real-time processing and identify information of data. File in HDFS modification is not possible due to a feature of WORM-based. Also a very large block size is inefficient to process a small file. MapReduce to perform parallel analysis on a cluster is not suitable for real-time processing because the analysis proceeds around the batch processing. In this paper, we proposes a method of real-time processing and dynamic classification of Big data using tags. The tagged data can be used to the real-time processing. In addition, it can assist batch processing of MapReduce. The proposed method to lower memory usage of Hadoop name node, and when performed MapReduce, it was effective to reducing the number of mappers generated. In addition, it was confirmed that the tags that are useful for real-time processing and dynamic classification.

상처받은 성인아이의 자존감 증진 프로그램 연구

김승현 서울신학대학교 2009 국내석사

초전도 에너지 저장 장치용 3상 사이리스터 브리지의 비대칭 제어에 관한 연구

김승현 한국해양대학교 대학원 2018 국내석사

일반적으로 3상 사이리스터 브리지 회로는 AC-DC 변환장치, 대형 모터의 가역속도 조정, 에너지 저장 장치 등 전압, 전류 제어의 여러 분야에서 사용되고 있다. 에너지 저장 장치에서는 현재까지 개발된 여러 가지 대용량 에너지 저장 장치들 중 초전도 에너지 저장 장치 (Superconducting Magnet Energy Storage, SMES)는 상대적으로 에너지 저장용량이 크고 응답속도가 빨라서 오랜 시간동안 잦은 충·방전이 요구되는 시스템에 적용하기에 적합하고 사이리스터 브리지를 대칭 제어하는 대신에 비대칭 제어를 하면 상대적으로 평균 출력전압은 감소하지만 유효전력을 최대화하면서 무효전력을 최소화하여 역률을 증가시킬 수 있다. 따라서 SMES용 3상 사이리스터 브리지 회로에서 사이리스터가 점호되는 각을 대칭 또는 비대칭 제어함으로써 특징을 분석하였고 에너지를 SMES에 저장하고 회생 시에는 저장된 에너지를 입력 전원 측에 공급하게 된다. 본 논문에서는 SMES에 에너지를 저장하기 위한 전력변환기인 3상 사이리스터에서 비대칭 제어를 함으로써 무효전력을 최소화 시켜 역률을 증가시킬 수 있는 방법에 대하여 연구하였다. KEY WORD: 초전도 에너지 저장 장치(Superconducting Magnet Energy Storage, SMES), 3상 사이리스터 브리지, 대칭 제어, 비대칭 제어 In this paper, in general three-phase thyristor bridge circuits are used in various fields of voltage and current control such as AC-DC converter, reversible speed adjustment of large motors, and energy storage devices. Among the various energy storage devices developed so far, superconducting energy storage devices have a relatively large energy storage capacity and high response speed, which is suitable for a system requiring frequent charge and discharge of a long time. In the SMES three-phase thyristor bridge circuit, energy is stored in the SMES by symmetrical or asymmetrical control of the alpha angles at which thyristors are turned on, and reverse voltage is generated during regeneration period in which to regenerate energy is supplied on the power supply side. This paper describes the control characteristics of power converters for SMES In this paper, we have studied a method to increase the power factor by minimizing reactive power by asymmetric control in a 3-phase thyristor, which is a power converter for storing energy in SMES. KEY WORD: Superconducting Magnet Energy Storage (SMES), 3-phase thyristor bridge, Symmetrical control, Asymmetrical control

한국인 분변유래 인체 장내 정상세균총을 이용한 Thiamphenicol의 미생물학적 독성평가

김승현 忠南大學校 大學院 2004 국내석사

The use of veterinary drugs in food-producing animals may result in trace quantities of the drugs and/or their metabolites being present as residues in edible tissues. The effects of veterinary drugs intended for use in food-producing animals on intestinal microflora have been evaluated in drug registration since these residues may pose a risk due to their antibiotic activity. This study was carried out to establish the ADI of thiamphenicol using the microbiological toxicity method, based on the Korean normal intestinal flora. Bacteroides fragilis was predominant organisms followed by Peptostreptococcus spp., Bifidobacterium spp., Bacteroides spp., Fusobacterium spp., Eubacterium spp., Clostridium spp., Enterococcus spp., Escherichia coli, Lactobacillus spp., was isolated from the Korean normal intesitinal microflora. A GM MIC of thiamphenicol against Fusobacterium spp., the most sensitive species among 10 isolated normal intestinal microflora in this study, was calculated as 1.88 ㎍/㎖. By use of the GM MIC value, we established the microbiological ADI of thiamphenicol to be 17.2 ㎍/ kg/ day. In order to find any relationship between the enzyme activity and inhibitory growth of bacteria by thiamphenicol, we measured the activity of hydrolases and reductases each of two, and then compared with its corresponding GM MIC. Bacterial activities of two reductases (nitrate reductase and azoreductase) were increased in proportion to the concentrations of thiamphenicol, whereas those of two hydrolases ( β-glucuronidase and β-glucosidase ) were not. The NOEC (equivalent to GM MIC for the calculation of the microbiological ADI) of thiamphenicol based on azoreductase activity was 2.0 ㎍/㎖, very similar value to 1.88 ㎍/㎖ obtained from the microbiological method. In summary, the microbiological method adopted in this study was able to provide with the calculation of the ADI of thiamphenicol. In addition, certain bacterial enzyme activity would also be utilized in place of (or in supplement for) the calculation of the microbiological ADI of a variety of antibacterial agents.

Inhibitory compounds from the fruits of Idesia polycarpa on nitric oxide production in microglial cell lines

김승현 서울大學校 大學院 2006 국내박사

시스템 인식 기법을 이용한 나노 구동 장치의 전달 특성 추정

김승현 성균관대학교 2006 국내석사

This thesis is concerned with identifying transfer functions of the nano translation device. The main objective of this thesis is to obtain correct transfer functions of this system by using identification tools in MATLAB. In many cases, the systems are so complex and huge that it is impossible to obtain correct models using only physical laws. These problems can be solved by system identification experimental method. In this thesis, transfer functions of the system is derived by using State-Space, ARX and ARMAX model structure based on input/output data. It is very difficult to design controller, because these order of transfer functions is high degree. So order of transfer function is decreased using model reduction. The best model structure is selected by fit rate, correlation function and the smallest order.

동적반복하중을 가한 외부 및 내부 연결 임플란트에서의 침하현상에 대한 연구

김승현 성균관대학교 일반대학원 2013 국내석사

[목적] 본 연구에서는 (1) 외부 및 내부 연결 임플란트에서 일정한 시간 후 가해진 추가적 조임 토크에 따른 지대주의 침하량을 측정하여 나사의 재조임에 의한 침하현상의 발생을 관찰하였으며, (2) 외부 및 내부 연결 임플란트에 동적반복하중을 가하여 주기횟수 (cycle)에 따라 단계적으로 발생된 지대주의 침하량을 비교 분석함으로써 하중의 기간에 따른 침하량의 변화를 임플란트 시스템별로 살펴보았다. [연구 재료 및 방법] 세 가지의 서로 다른 임플란트-지대주 조합이 사용되었다 (Int-1군: 내부 원추형 연결 임플란트 + 일체형 지대주 (N = 10); Int-2군: 내부 원추형 연결 임플란트 + 분리형 지대주 (N = 10); Ext군: 외부 육각형 연결 임플란트 + 분리형 지대주 (N = 10)). Digital torque gauge를 사용하여 30 N㎝의 조임 토크로 최초의 나사 조임 후 10분 간격으로 두 번의 재조임을 시행하였다. Electronic digital micrometer (EDM)를 이용하여 임플란트-지대주 복합체의 전체 길이를 측정하였으며 조임 토크에 의해 감소된 길이를 나사의 재조임에 의한 지대주의 침하량으로 간주하였다. ISO 규정에 따라 25 N ~ 250 N, 14 ㎐, sine 파형의 동적반복하중을 지대주 장축과 30° 경사각도에서 주기횟수 (1, 2700, 5400, 8100, 18900, 81000, 486000 cycle)에 따라 단계적으로 가한 후, EDM을 이용하여 동일한 방법으로 하중의 기간에 따른 지대주의 침하량을 측정하였다. [결과] 반복하중 전, 나사의 재조임에 의하여 세 군에서 모두 통계적으로 유의한 지대주 침하현상이 발생하였으며, 침하량은 Int-2군 > Int-1군 > Ext군 순으로 많았다 (P < 0.05). 반복하중에 의한 지대주의 침하는 Int-1군과 Int-2군에서 대부분 0 ~ 1 cycle 사이에 발생하였으며 Int-1군의 경우 5400 cycle (약 2일) 이후, Int-2군의 경우 8100 cycle (약 3일) 이후에서는 침하량의 유의한 차이가 있다고 볼 수 없었다. Ext군의 경우 모든 순차적 주기횟수 구간에서 침하량의 차이가 통계적으로 유의하다고 할 수 없었다 (P > 0.05). 반복하중에 의해 세 군에서 모두 통계적으로 유의한 지대주 침하가 관찰되었으며, Int-2군 > Int-1군 > Ext군 순으로 침하량이 많았다 (P < 0.05). [결론] 외부 및 내부 연결 임플란트에서 나사의 재조임 및 동적반복하중의 기간에 따라 다양하고 유의한 지대주의 침하가 관찰되었다. [Purpose] This study (1) observed the occurrence of settling by screw retightening in external and internal connection implant systems by measuring the settling values of abutments according to additional tightening torques that were added after a certain passage of time, and (2) looked into changes of the settling values according to the loading period by implant systems through a comparative analysis of the settling values of abutments that occurred by adding step by step dynamic cyclic loading to external and internal connection implant systems according to cycles. [Materials and methods] Three different implant-abutment connection systems were used (Int-1: internal tapered conical connection + one-piece abutment (N = 10); Int-2: internal tapered conical connection + two-piece abutment (N = 10); Ext: external hex butt joint connection + two-piece abutment (N = 10)). Screw retightening conducted twice at intervals of 10 min. after initial tightening of the screw with 30 N㎝ torque using a digital torque gauge. The total lengths of the implant-abutment samples were measured using electronic digital micrometer (EDM), and considered the reduced length by tightening torque as the settling value of abutment by screw retightening. After adding step by step dynamic cyclic loading with sine waveform of 25 N ~ 250 N, 14 ㎐ in compliance with ISO regulations according to cycles (1, 2700, 5400, 8100, 18900, 81000, 486000) at the inclined angle of 30° from the long axis of an abutment, measured the settling values of abutments according to the loading period with the same method using EDM. [Results] Before the cyclic loading, the settling of abutments by screw retightening was shown to be statistically significant in all of the three groups, and the settling values were greater in the order of Int-2 group > Int-1 group > Ext group (P < 0.05). The settling of abutments by cyclic loading appeared mostly between 0 ~ 1 cycle in Int-1 group and Int-2 group. For Int-1 group, there was shown to be no significant difference in the settling values after 5400 cycles (about two days), whereas for Int-2 group there was no significant difference after 8100 cycles (about three days). For Ext group, there was no statistically significant difference in the settling values in the section of all the numbers of the sequential cycles (P > 0.05). In all the three groups, a statistically significant settling of abutments was observed by cyclic loading, and the settling values were greater in the order of Int-2 group > Int-1 group > Ext group (P < 0.05). [Conclusion] In accordance with the screw retightening and the period of dynamic cyclic loading, it was observed that there was diverse and significant settling of abutments in external and internal connection implant systems.

Optimal Trajectory Generation and Robust Control of a Launch Vehicle during Ascent Phase

김승현 서울대학교 대학원 2018 국내박사

This research focused on trajectory generation and control of a flexible launch vehicle during ascent flight. An important issue of a launch vehicle design is generating optimal trajectory during its atmospheric ascent flight while satisfying constraints such as aerodynamic load. These constraints become more significant due to wind disturbance, especially in the maximum dynamic pressure region. On the other hand, modern launch vehicles are becoming long and slender for the reduction in structure mass to increase payload. As a result, they possess highly flexible bending modes in addition to aerodynamically unstable rigid body characteristics. This dissertation proposes a rapid and reliable optimization approach for trajectory generation via sequential virtual motion camouflage (VMC) and non-conservative robust control for an unstable and flexible launch vehicle. First, an optimal trajectory is generated in a rapid and reliable manner through the introduction of the virtual motion camouflage. VMC uses an observed biological phenomenon called motion camouflage to construct a subspace in which the solution trajectory is generated. By the virtue of this subspace search, the overall dimension of the optimization problem is reduced, which decreases the computational time significantly compared to a traditional direct input programming. Second, an interactive optimization algorithm is proposed to find a feasible solution easier. For this, the constraint correction step is added after VMC optimization. Since VMC is a subspace problem, a feasible solution may not exist when subspace is not properly constructed. In order to address this concern, a quadratic programming (QP) problem is formulated to find a direction along which the parameters defining the subspace can be improved. Via a computationally fast QP, specific parameters (such as prey and reference point) used in VMC can be refined quickly and sequentially. As a result, the proposed interactive optimization algorithm is less sensitive to the initial guess of the optimization parameters. Third, a non-conservative 2-DOF H infty controller for an unstable and flexible launch vehicle is proposed. The objectives of the control system are to provide sufficient margins for the launch vehicle dynamics and to enhance the speed of the closed-loop response. For this, a robust control approach is used. The key of the control design is to overcome conservativeness of the robust control. The baseline controllers using the optimal control such as LQG and LQI are designed prior to a robust controller. These optimal controllers are used to find a desirable shape of the sensitivity transfer function in order to reduce conservativeness of the robust control. After implementation and analysis of the baseline controllers, an improved sensitivity weighting function is defined as a non-conventional form with different slopes in the low frequency and around crossover frequency, which results in performance enhancement without loss of robustness. A two-degree-of-freedom H infty controller is designed which uses feedback and feedforward control together to improve tracking performance with the proposed sensitivity weighting function as a target closed-loop shape. The resulting H infty controller stabilizes the unstable rigid body dynamics with sufficient margins in the low frequency, and also uses gain stabilization in addition to phase stabilization to handle the lightly damped bending modes in the high-frequency region.