• 한국수소및신에너지학회논문집
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• 제24권4호
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• pp.320-325
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• 2013

TUnitized reversible fuel cells (URFC) combine the functionality of a fuel cell and electrolyzer in one unitized device. For a URFC with proton exchange membrane, a titanium (Ti)-felt is applied to the gas diffusion layer (GDL) substrate at the oxygen electrode, and additionally titanium (Ti)-powders and TiN-powders are loaded in the GDL substrate as a micro porous layer (MPL). Double porous layer with TiN MPL was not acceptable for the URFC because both of fuel cell performance and electrolysis performance are degraded. The double porous layer with Ti-powder loading in the Ti-felt substrate influence rearly for the electrolysis performance. In contrast, the change of pore-size distribution brings a significant improvement of fuel cell performance under fully humidification conditions. This fact indicates that the hydrophobic meso-pores in the GDL play an important role for mass transport.

• 한국광학회지
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• 제7권1호
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• pp.66-71
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• 1996

Floating guard ring(FGR) 구조를 갖는 avalanche photodiode(APD)는 제작이 매우 간단하고 제작된 소자의 신뢰성이 뛰어나기 때문에 고감도 특성의 고속동작 수광소자로 적합하다. 본 연구논문에서는 FGR APD의 구조설계, 제작공정 및 특성 측정 결과에 대해 논의하였다. FRG-APD는 이중확산 방법으로 제작하였으며 FGR이 가드링으로서 동작함을 2차원 이득특성 측정으로부터 확인할 수 있었다. 제작된 APD는 35GHz의 이득-대역폭 곱을 나타내었으며 2.5Gbps NRZ(Non-return-to-zero) 광신호에 대한 수신감도는 비트오율이 $10^{-9}$일 때 -31.9dBm이었다.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1530-1537
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• 1998

Mixture formation is one of the significant factors to improve combustion performance of an spark ignition engine. This is affected by spray and atomization characteristics of injector. In the case of EGI system, air-fuel mixing period is so short that a lot of fuel-film and liquid-fuel flow into cylinder. Since this fuel-film is not burnt perfectly in cylinder, it is exhausted in the form of HC emission. In this paper, three measurement techniques were utilized to measure spray characteristics and the amount of fuel-film in the cylinder. At first, PMAS was used to measure the spray characteristics such as size distributions, SMD, and spray angle. Secondly the amount and distribution of fuel-film which flow into through intake valve could be measured quantitatively using the fuel-film measuring device. And lastly, by optical fiber type spark plug used to detect the diffusion flame, the amount of unburned HC was measured. As the result of these experiments, the information of optimal spray characteristics and injection condition to minimize fuel-film could be built up.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1001-1006
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• 2005

A new fabrication method is proposed to form the stacked polysilicon gate by nitridation in $N_2$ atmosphere using conventional LP-CVD system. Two step stacked layers with an amorphous layer on top of a polycrystalline layer as well as three step stacked layers with polycrystalline films were fabricated using the proposed method. SIMS profile showed that the proposed method would successfully create the nitrogen-rich layers between the stacked polysilicon layers, thus resulting in effective retardation of dopant diffusion. It was observed that the dopants in stacked films were piled-up at the interface. TEM image also showed clear distinction of stacked layers, their plane grain size and grain mismatch at interface layers. Therefore, the number of stacked polysilicon layers with different crystalline structures, interface position and crystal phase can be easily controlled to improve the device performance and reliability without any negative effects in nano-scale CMOSFETs.

• Current Photovoltaic Research
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• 제2권3호
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• pp.124-129
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• 2014

Dye-sensitized solar cells (DSSCs) are considered as promising alternatives to conventional photovoltaic device. However, commercialization of the DSSCs is restricted due to the low efficiency. In this paper, highly efficiency DSSCs were fabricated by the adding the TBA to the $TiO_2$ paste. $TiO_2$ photoanode added 0.2 M TBA in DSSCs are shown the best efficiency of 9.14 %. This result ascribed to improvement of the connection between the $TiO_2$ nanoparticles by the addition of the optimized amount TBA. The morphology of the photoanode was observed by FE-SEM. Further investigation about the kinetics of the electrochemical processes are performed by the EIS analysis. Longest diffusion length was obtained in case adding 0.2 M of TBA to $TiO_2$ paste, which was matched well with the improved efficiency.

• 한국CDE학회논문집
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• 제18권6호
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• pp.399-406
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• 2013

This paper describes a new simulation technique for advection-diffusion phenomena over the sea surface using the lattice Boltzmann method (LBM), capable of predicting oil dispersion from tankers. The LBM is used to solve the pollutant transport problem within the framework of the ocean environment. The sea space is represented by the lattices, where each lattice has the information on oil transportation. Since dispersed oils (i.e., oil droplets) at sea are transported by convection due to waves, buoyancy, and turbulent diffusion, the conservation of mass and many physical oil transport rules were used in the prediction model. Since the LBM is modeled using the uniform lattices and simple rules, it can be easily accelerated by the parallel mechanism, for example, GPU-accelerated method. The proposed model using the LBM is used to simulate a simple pollution event with the oil pollutants of 10,000 kL. The simulation results indicate that the LBM method accelerated with the GPU is 6 times faster than that without the GPU.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1022-1026
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• 2007

We have demonstrated new functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of silver via photo-induced diffusion in thin chalcogenide films is considered. The influence of silver on the properties of the newly formed materials is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Silver saturated chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in programmable metallization cell (PMC) devices. In this paper, we investigated electrical and optical properties of Ag-doped chalcogenide thin film on changed thickness of Ag and chalcogenide thin films, which is concerned at Ag-doping effect of PMC cell. As a result, when thickness of Ag and chalcogenide thin film was 30 nm and 50 nm respectively, device have excellent characteristics.

• 대한전자공학회논문지SD
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• 제40권11호
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• pp.1-8
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• 2003

본 논문에서는 소스/드레인 및 게이트의 불순물에 따른 실리사이드의 의존성을 면저항과 단면 특성 등의 분석을 통하여 연구하였다. 급속 열처리 후에는 As, P, BF₂, B/sub 11/ 등과 같은 불순물에 대한 먼저항의 차이가 거의 나지 않았다. 하지만 실리사이드 형성 후히 고온 열처리시에 그 특성이 매우 크게 변화하였다. BF₂를 주입한 시편에서의 특성이 가장 좋게 나타난 반면, As를 주입한 실리사이드의 특성이 가장 열화되었다. BF₂를 주입한 시편에서의 실리사이드 특성 향상은 flourine에 의한 니켈의 확산 방지 때문인 것으로 여겨진다. 그러므로 실리사이드의 성능 향상을 위해 Ni의 확산을 방지시키는 것이 매우 필요하다.

• Journal of Electrochemical Science and Technology
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• 제14권1호
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• pp.31-37
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• 2023

Owing to the rapid climate change, a high-performance energy storage system (ESS) for efficient energy consumption has been receiving considerable attention. ESS, such as capacitors, usually has issues with the ion diffusion of electrode materials, resulting in a decrease in their capacitance. Notably, appropriate pore diameter and large specific surface area (SSA) may result in an effective ion diffusion. Therefore, graphene and multi-walled carbon nanotube (graphene@MWCNT) hybrid nanomaterials, with covalent bonds between the graphene and MWCNT, were prepared via an edge-chemistry reaction. The properties of these materials, such as high porosity, large SSA, and high electroconductivity, make them suitable to be used as electrode materials for capacitors. The optimal ratio of graphene to MWCNT can affect the electrochemical performance of the electrode material based on its physical and electrochemical properties. The supercapacitor using optimal graphene-based hybrid electrode material exhibited highest specific capacitance value as 158 F/g and excellent cycle stability.

• 대한전자공학회논문지SP
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• 제42권3호
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• pp.107-114
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• 2005

선으로 구성된 회로도나 설계도 같은 특수 목적 영상을 처리할 경우 에지가 강조된 영상을 필요로 한다. 또한 프린터, 팩시밀리, LCD TV 등과 같은 이진 출력 장치에 연속 계조 영상을 표현하기 위한 디지털 해프토닝 방법 중 오차 확산 방법으로 이진 영상을 생성할 경우 에지가 흐려진다. 본 논문은 회로도나 설계도 등의 영상 뿐 아니라 이진 출력 장치 등에 사용되는 이진 영상의 에지를 강조하는 방법을 제안한다. 인간의 눈은 한 화소의 명암값이 아니라 국부 평균을 인식한다는 것을 이용하여 제안 방법은 원화소의 명암값과 $3{\times}3$ 블록의 평균 명암값과의 차이 값에 공간적 위치 값에 따른 가중치를 결합하여 국부 공간 변화량(LAM: local activity measure)을 사용한다. 제안된 시스템은 또한 LAM에 평균 명암도를 곱하여 얻어진 에지 강조 정보량(IEE: information of edge enhancement)을 사용한다. IEE를 양자화기 입력에 더하여 이진 영상의 에지를 강조한다. 컴퓨터 시뮬레이션은 제안 방법이 기존의 방법에 비해 영상의 에지가 강조되어 시각적으로 선명한 영상을 생성한다. 또한 거리에 따른 에지 상관도와 로컬 평균 일치도를 이용하여 제안 방법과 기존 방법의 특성을 분석한다.