Photoluminescence enhancement in hybrid nanomaterials of conjugated polymer and PbS quantum dots

Truong, Phuoc Loc 중앙대학교 대학원 2020 국내석사

우리는 양자점과 공액 폴리머를 혼합하여 PbS 양자점의 광발광 향상에 대해 연구한다. 본 연구에서, 전자-정공 재조합의 메커니즘이 더 명확해진다. 전자-정공 쌍의 광 발생은 공액 중합체로부터 PbS 양자점쪽으로 이동하여 발광 다이오드에 적용되는 발광 강도를 향상시킨다. PbS QD는 활발히 연구되고 있으나 수분, UV 조명 및 산소에 의한 분해된다는 단점에 여전히 직면하고 있다. 우리는 150nm 청색이동 및 더 강한 발광 강도를 보여주는 PbS QD를 합성하기 위해 수정된 방법을 제공한다. 용매, 온도 및 진공의 조건을 통제하고 올레일아민을 1- 옥타네티올로 대체하여 QD의 안정성을 향상시킬 뿐만 아니라 직경 2.8 nm의 더 작은 크기의 나노 입자를 제공한다. We research on the photoluminescence enhancement of PbS quantum dots (QDs) by blending the QDs with a conjugated polymer. In this study, the mechanism of electron-hole recombination is more prominent. The photogeneration of the electron-hole pairs moves toward PbS QDs from a conjugated polymer that enhances the luminescence intensity applied in light-emitting diodes (LEDs). Additionally, PbS QDs have been well researched. However, there is still challenging to face degradation by moisture, UV illumination, and oxygen. Here, we give out a modified method to synthesize PbS QDs showing 150nm blueshift and the stronger luminescence intensity. The factors of solvent, temperature, and vacuum are investigated. The replacement of oleylamine (OLA) with 1-octanethiol (OT) improves the stability of the QDs as well as giving smaller-sized nanoparticles at a diameter of 2.8 nm.

Accurate, efficient, and robust 3D reconstruction of static and dynamic objects

Lee, Kyoung-Rok ProQuest LLC UMI Dissertation Publishing 2014 국내박사

Liquid Eutectic Gallium-Indium (EGaIn) as a vacuum-free alternative electrode for organic solar cells

Pham, Hau Thanh Viet Yeungnam University 2017 국내박사

Micro-texturing technology on cylindrical stainless steel surface for biomedical applications

Truong, Dinh Sy Kangwon National Univ 2013 국내석사

Evaluation of micro-texturing technology on biomedical material has been developing in recent decades. In particular, increase or reduction of friction force on surgical equipment has fascinated a larger number of researchers. In this study, we evaluated the micro-texturing technique that changed the needle surface's structure. The results lead to orientation how to minimize pain and damage during injection process or improve the biocompatibility for implantable devices. Biomedical biopsy needles were made from stainless steel 316L. Stainless steel 316L contains Iron, Molybdenum, Chromium and Nickel as main compositions. In general, Chromium helps to prevent corrosion and scratch, Nickel provides smooth and Molybdenum helps to have a greater hardness and maintains a cutting edge. Furthermore, in order to measure friction force, the material that is identical human tissue called phantom tissue was utilized. After that, the textured biopsy needle will be injected through the tissue for calculating friction force. Also, we designed a surface friction measuring system that includes movement and fix part. The movement part brings tissue and move in vertical direction. The fix part helps to keep needle. In order to texture the surface of biopsy needles, a PDMS mold was design as hexahemispherical shape with the pitch of 30?m. Before rolling needles for fabricating patterns, AZ 4620 (PR-photoresist) was poured upon the PDMS mold and carried out doctoring step. After this, PR patterned needles were dipped into etchant solution for etching process, leading to micro-texturing surface. The solution contains FeCl3: HCl: HNO3 = 10:10:5 in weight ratio. The etching stage implemented at 40℃ and etching time interval ranged from 10 seconds to 60 seconds. In general, the results of experiments will provide the influences of pattern depth, pattern diameter as well as velocity of injection.

Simultaneously determination of 14 hypoglycemic drugs in human urine by liquid chromatography - tandem mass spectrometry

Truong, Quoc-Ky Kangwon National University 2018 국내박사

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for the simultaneous quantification of 14 oral hypoglycemic drugs in human urine. For the first time, metformin and phenformin which are highly polar compounds were simultaneously separated and quantified with other less polar hypoglycemic drugs. Metoprolol was used as internal standard (IS). Oral hypoglycemic drugs were chromatographed on a Hilic column (50 x 3.0 mm i.d., 3 µm) combined with C18 guard column (4.0 x 3.0 mm i.d.) using a 30:70 (v/v) mixture of 1 mM ammonium formate pH 5.0 (mobile phase A) and acetonitrile (mobile phase B) as mobile phase at a flow rate of 0.35 mL/min, column temperature was at 350C. The gradient program started from 0% mobile phase B, linearly increased to 70% B from 0.2 to 10.0 min and then decreased to the start condition (0% mobile phase B) in 1 min. Mobile phase B was held at 0% for 9.0 min (from 11.0 min to 20.0 min). The total run time was 20.0 min. API-3200 LC-MS/MS in multiple reaction monitoring (MRM) mode was used for detection. Mass spectrometers and production ion mass spectrum of all standards were operated in the positive ion detection mode with an ESI source for mass analysis and detection. Parameters of MS were optimized with analyst software (version 1.4.2) to process the data with the guidelines suggested by the manufacturer (AB Sciex, 2013). The method developed was validated in terms of system suitability, specification, sensitivity (the detection limit LOD, the quantification limit LOQ), linearity, carryover, qualitative matrix effect precision and accuracy, robustness, stability according to ICH (Q2 2005) and bioanalytical method validation FDA guidance. The calibration curves were linear over the concentration range of 2-300 ng/ml for sitagliptin, rosiglitazone, pioglitazone, repaglinide, phenformin and mitiglinide, 5-400 ng/ml for glipizide, gliclazide, nateglinide, glibenclamide, glimepiride, metformin and 20-500 ng/ml for tolbutamide, chlorpropamide with r2 = 0.99. The quantification limit LOQ was 2 ng/ml for sitagliptin, rosiglitazone, pioglitazone, repaglinide, phenformin and mitiglinide, 5 ng/ml for glipizide, gliclazide, nateglinide, glibenclamide, glimepiride, metformin and 20 ng/ml for tolbutamide, chlorpropamide. Criteria for acceptability of the data included intraday and interday precision and accuracy at LOQ concentration were below 20%; at medium, low and high concentration were below 15%. The method was precise and sensitive enough for the simultaneous determination of 14 hypoglycemic drugs in urine. . Recovery and matrix effect of the drugs ranged between 80% and 99%: metformin (82% - 93%), chlorpropamide (82% - 96%), phenformin (80% - 84%), sitagliptin (81% - 95%), tolbutamide (80% - 86%), gliclazide (80% - 82%), glipizide (86% - 99%), mitiglinide (81% - 89%), nateglinide (80% - 81%), rosiglitazone (81% - 90%), pioglitazone (80% - 87%), glibenclamide (80% - 85%), glimepiride (80% - 82%) and repaglinide (82% - 93%). The criteria for acceptability calculated for the concentration was not more than 15%. Stability of all compounds at each level (LOQ, low, medium and high) in short-term and long-term had the maximum relative error (%) of 14.34% which was within the criteria (±15% of the nominal concentration). Selectivity, system suitability, carry over and robustness of the validation method were within the acceptable criteria. This analytical method was successfully applied to a human urine sample and metformin and nateglinide could be effectively detected and quantitated after two days of the administration of the drugs.

Vapor-phase polymerized thin films and seeding-polymerized nanofibers membranes of Poly(3,4-ethylenedioxythiophene) for optoelectronic applications

Truong, Thuy Le 성균관대학교 2007 국내석사

As with other conducting polymers, poly(3,4-ethylenedioxythiophene) is considered as a promising material for optoelectronic devices. In most of those optoelectronic applications as buffer or electrode layers, the surface and/or interface of PEDOT coating layer substantially influences mobility, quantum efficiency and stability of charge carriers as well as assembled devices. Previous studies show that the effect of dielectric surface on charge mobility is due to surface-induced morphology of polythiophene. In this sense, the vapor-phase polymerization (VPP) of PEDOT is a promising technology in various optoelectronic applications to provide a thin, uniform, and highly-conductive PEDOT coating. However, not only the conductivity enhancement but also the surface morphology of PEDOT VPP should be further explored to be adopted in optoelectronic device. In addition, the conductivity of the PEDOT coating in relation with surface smoothness and transparency should be identified to be used as thin film coating in optoelectronic devices. In this study, our overall goal is to produce well-characterised PEDOT film for optoelectronic applications by the formation of robustly nanostructured PEDOT coating. The surface morphology of PEDOT was investigated in the vapor-phase polymerization of the thiophene monomer on a flexible polyethyleneterphthalate (PET) substrate film. The PET surface was modified with ethylene diamine maintaining the surface roughness within 2 nm to create amine and amide groups for the enhanced hydrophilic interaction with Fe(III)-tosylate (Fe(OTs)3) and for the desirable hydrogen bonding with thiophene monomer as well as PEDOT. Polymerization rate was reduced by incorporating pyridine as a reaction retardant to control the surface roughness and conductivity of PEDOT thin films. The optimal conditions of pyridine and glycerol were found at a pyridine/Fe(OTs)3 molar ratio of 0.5 and a glycerol concentration of 4~5 wt%, respectively, providing the conductivity up to 500 S/cm and the surface roughness < 2 nm.

Shrinkage and Creep Behavior of Amorphous Steel Fiber-Reinforced Concrete

Truong Gia Toai 숭실대학교 일반대학원 2014 국내석사

콘크리트 구조물은 기초, 지반, 철근 등에 의해 구속되어 있다. 콘크리트의 건조 수축은 인장 강도에 영향을 줄 수 있고, 인장 응력이 콘크리트의 인장 강도를 넘어서면 크랙이 발생한다. 일반 콘크리트가 취성이 있고 인장 강도가 낮기 때문에, 크랙의 발달이 변형을 증가시킬 수 있으며, 콘크리트 구조물 자체를 파괴시키고 결과적으로 전체 구조물을 붕괴시킬 수 있다. 최근, 섬유가 수축, 크랙 발생을 포함하는 수축 거동 그리고 시간에 따른 크리프 거동에 미치는 영향을 조사하기 위해 섬유 보강 콘크리트가 널리 사용되었다. 이는 섬유와 콘크리트를 조합해서 콘크리트에 보다 연성을 주고 크랙의 영향을 완화하기 위한 방법이다. 이 방법은 콘크리트 배합 속에 섬유들을 포함시키는 것이 가능하고, 작업성의 영향이 그다지 크지 않은 경우에 유용하다. 사용하는 섬유들은 기름 야자나무 섬유, 강섬유, 그리고 폴리프로필렌 섬유 등 여러 가지가 있다. 시간에 따른 섬유 보강 콘크리트의 상태를 연구하는 중에, 섬유의 사용이 수축과 크리프 감소에 영향을 주며 이로 인해 크랙의 폭을 크게 줄여준다는 것이 확인되었다. 이 연구에서는 POSCO에서 생산한 비정질 강섬유(amorphous steel fibers)를 사용한다. 비정질 강섬유가 수축과 크리프 거동에 미치는 영향은 자기 수축, 무 건조 수축, 링 구속 수축, 슬래브 구속 수축, 인장 크리프 및 압축 크리프 시험을 사용해서 조사했다. 사용된 섬유의 함유량은 0, 0.2, 0.3, 0.4, 그리고 0.6% 이다. 시험 결과, 비정질 강섬유를 콘크리트 배합에 섞는 것이 무 건조 수축, 크래킹 시간 지연 그리고 크랙 폭 감소에 큰 영향을 미칠 수 있었다. 그러나, 비정질 강섬유가 자기 수축, 무 건조 수축, 링 구속 수축, 슬래브 구속 수축, 인장 크리프 및 압축 크리프에 미치는 영향은 크지 않았으며 명확하지 않았다. 따라서, 이 같은 거동을 완전히 이해하기 위해서는 추가적인 연구가 필요하다. In reality, concrete structures were restrained by other members such as foundations, subgrades, reinforcement, and so on, drying shrinkage of concrete could induce tensile stresses, once tensile stresses overcomes tensile strength of concrete, crack occurs. Due to the brittleness and low tensile strength of normal concrete, the development of crack in concrete is able to increase the deflection, break up the concrete structures themselves, and may lead to collapse the whole structure. In recently, fibers reinforced concrete was widely performed to investigate the effect of fibers on free shrinkage, shrinkage behavior inducing cracking, and creep behavior of concrete as time progress. The method is combining fibers and concrete to make concrete more ductile and to lessen the effect of cracking. It is advantageous that incorporating fibers in concrete mix is possible and the effect of workability is not so considerable. There are different types of fibers in use such as oil palm trunk fibers, steel fibers, polypropylene fibers, etc… During studies of fiber reinforced concrete following time development was investigated, the use of fibers was effective on reducing shrinkage, creep, thus reduced significantly crack width. This study presents newly amorphous steel fibers manufactured by POSCO Steel Company. The effect of amorphous steel fibers on shrinkage and creep behavior was investigated by performing autogenous shrinkage, free drying shrinkage, ring restrained shrinkage, slab restrained shrinkage, tensile creep, and compressive creep tests. The fiber volume fractions used was 0, 0.2, 0.3, 0.4, and 0.6%. Based on the test results, the addition of amorphous steel fibers into concrete mix could significantly reduce free drying shrinkage, delay cracking time, as well as reduce crack wide. However, the effect of amorphous steel fibers on autogenous shrinkage, tensile and compressive creep was not considerable, and not evident. Thus, further research is necessary to understand completely these behaviors.

Seaport Throughput Analysis and Global Risk Management by Using Effective Decision‐Making Theory: A Case Study of Vietnamese Ports

TRUONG NGOC CUONG 한국해양대학교 대학원 2022 국내박사

Recently, globalisation has spurred the importance of seaport operations and terminal capacity in the supply chain networks. Seaports play a vital role in the economy of many countries and regions in which ports must be operated in an efficient way for mitigating supply chain risk. Understanding the underlying mechanism of port operation and optimizing profits is essential business objective for port authorities. As matter of fact, port interaction is a nonlinear dynamic process with much complex behavior. Several socioeconomic factors influenced port throughput such as the gross domestic product, fixed assets investments, imports, and exports, etc. Moreover, seaport ecosystems can no longer be the isolated nodes in which they dynamically interact with each other at only a local scale in regional port governance; but within the globally integrated networks of complex supply chains. Thus, it is beneficial to understand the underlying dynamics of complex seaport networks. By analysing chaotic system in port management, the managers can gain better insights into the complex and nonlinear properties of the port interactions in the real market then the optimal management solution can be undertaken. In this dissertation, the port operation system is considered by utilizing four dimensions of the fractional Lotka-Volterra model. First, the dynamic behaviours of the port operation system are investigated by using nonlinear techniques such as equilibrium evaluation, bifurcation, Lyapunov, and time series investigation. The dynamical analysis indicates that the port competition system shows a complex and highly nonlinear behaviour, notably illustrating unstable equilibria and even chaotic phenomena. Next, based on dynamical analysis results, novel multi-criteria decision-making techniques realized by the neural network prediction controller (NNPC) and adaptive fractional-order super-twisting sliding mode control (AFOSTSM) have been utilized for dealing with throughput dynamics under parametric perturbations and external disturbances. Particularly, the active control algorithms are implemented to ensure the recovery strategy for the throughput growth trend of Vietnam ports against system uncertainty and external disturbance. The case study has confirmed the efficacy of the proposed strategy by using system dynamics and control theory. The simulation results show that the average growth rates of container throughput can be ensured up to 7.46% by exploiting the proposed method. The presented method can be also utilized for providing managerial insights and solutions for efficient port operations. In addition, the control strategies with neural network forecasting can help managers obtain timely and cost-effective decision-making policy for port operations against unprecedented disruptions such as the Covid-19 pandemic.

Isolated high boost DC-DC converter based on current-fed topology

Duong, Truong Duy Chonnam National University 2018 국내석사

The renewable energies such as solar cells, fuel cells, photovoltaic have a low voltage and variable, the renewable energies are dependent on the weather conditions, and not stability. To connect them to the industrial application, many high boost DC-DC converters have been presented and investigated to convert low DC voltage into a high DC bus voltage. The isolated topologies can provide the high voltage gain for high step-up ability application. Thus, the isolated boost DC-DC converter based on a new three switches in fuel cell applications is presented in this paper. The major advantages of the proposed current-fed with three switches converter are as follows: continuous input current; decrease one active switch and no use snubber circuit; the primary and secondary voltage waveforms of the high-frequency transformer are not changed; not using snubber capacitor circuit. The operating principles, analysis and parameters selection of the proposed current-fed with three switches converter have been discussed. A prototype of 400 W has been built in the laboratory to verify the performance of the proposed current-fed with three switches converter was used to clarify the DC output voltage at 400 V. The simulation and experimental results are shown to validate the theoretical analysis.

Development of Smart Wearable Devices with AI-Enhanced for Smart Healthcare Applications Truong Tien Vo

VO TRUONG TIEN 국립부경대학교 대학원 2025 국내박사