• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1265-1266
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• 2006

Multi-stacked HTS tapes are needed to conduct large current in the power application of superconducting machine. This paper deals with the transport current loss of multi-stacked YBCO coated conductor. YBCO coated conductor that was used in this experiment has two Cu layers above and below of YBCO layer for stabilization. Transport losses of four different stacks, single, 2 stack, 3 stack and 4 stack, were measured. Measured results were compared analytic equation suggested by Norris.

• ETRI Journal
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• 제38권5호
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• pp.903-910
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• 2016

We propose a novel multi-stack (MS) technique for a compact and wideband electromagnetic bandgap (EBG) structure in high-speed multilayer printed circuit boards. The proposed MS technique efficiently converts planar EBG arrays into a vertical structure, thus substantially miniaturizing the EBG area and reducing the distance between the noise source and the victim. A dispersion method is presented to examine the effects of the MS technique on the stopband characteristics. Enhanced features of the proposed MS-EBG structure were experimentally verified using test vehicles. It was experimentally demonstrated that the proposed MS-EBG structure efficiently suppresses the power/ground noise over a wideband frequency range with a shorter port-to-port spacing than the unit-cell length, thus overcoming a limitation of previous EBG structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1725-1726
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• 2006

Multi-stacked HTS tapes are needed to conduct large current in the power application of superconducting machine. This paper deals with the transport current loss of multi-stacked YBCO coated conductor. YBCO coated conductor that was used in this experiment has two Cu layers above and below of YBCO layer for stabilization. Transport losses of four different stacks, single, 2 stack, 3 stack and 4 stack, were measured. Measured results were compared analytic equation suggested by Norris.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.68-75
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• 2010

The one of the major problems in the development of PEMFC was regarding to the assurance of sealing on stack. The failure on the sealing creates the problems of fuel leakage, mixing, internal combustion, damage on parts and can be a direct reason for the degrading the efficiency of fuel cell. This paper studies on the analytical approach for improving the contacting pressure distribution on the gasket at the evaluation on the sealing of fuel cell stack. So, the assembly analysis on multi layered fuel cell stack was performed. The research on the simplification of finite element model was performed for three dimensional analysis at the multi layered state. The improved contact pressure distribution was obtained through the case studies on gasket for better sealing. In addition, the number of the cell was determined for the effective analysis and the structural characteristics were evaluated based on this research.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.53-58
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• 2023

The storage capacity of 3D-NAND flash memory has been enhanced by the multi-layer dielectrics. The deposition process has become more challenging due to the tight process margin and the demand for accurate process control. To reduce product costs and ensure successful processes, process diagnosis techniques incorporating artificial intelligence (AI) have been adopted in semiconductor manufacturing. Recently there is a growing interest in process diagnosis, and numerous studies have been conducted in this field. For higher model accuracy, various process and sensor data are required, such as optical emission spectroscopy (OES), quadrupole mass spectrometer (QMS), and equipment control state. Among them, OES is usually used for plasma diagnostic. However, OES data can be distorted by viewport contamination, leading to misunderstandings in plasma diagnosis. This issue is particularly emphasized in multi-dielectric deposition processes, such as oxide and nitride (ON) stack. Thus, it is crucial to understand the potential misunderstandings related to OES data distortion due to viewport contamination. This paper explores the potential for misunderstanding OES data due to data distortion in the ON stack process. It suggests the possibility of excessively evaluating process drift through comparisons with a QMS. This understanding can be utilized to develop diagnostic models and identify the effects of viewport contamination in ON stack processes.

• 반도체디스플레이기술학회지
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• 제8권1호
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• pp.13-17
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• 2009

In PRAM applications, the devices can be made for both binary and multi-state storage. The ability to attain intermediate stages comes either from the fact that some chalcogenide materials can exist in configurations that range from completely amorphous to completely crystalline or from designing device structure such a way that mimics multiple phase chase phenomena in single cell. We have designed stack-structured phase change memory cell which operates as multi-state storage. Amorphous $Ge_xTe_{100-x}$ chalcogenide materials were stacked and a diffusion barrier was chosen for each stack layers. The device is operated by crystallizing each chalcogenide material as sequential manner from the bottom layer to the top layer. The amplitude of current pulse and the duration of pulse width was fixed and number of pulses were controlled to change overall resistance of the phase change memory cell. To optimize operational performance the thickness of each chalcogenide was controlled based on simulation results.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 추계학술대회 논문집
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• pp.338-338
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• 2015

VRFB(Vanadium Redox Flow Battery)는 바나듐계 이온을 전해질로 사용하는 레독스 흐름 전지로, 전해질의 양이 전지의 용량을 결정하기 때문에 주로 대용량의 전력이 필요한 플랜트 등에서 주로 사용하는 전지이다. 이 VRFB내에는 Current collector의 부식 방지용으로 두꺼운 Graphite판을 BP(Bipolar plate)로 사용한다. 플랜트에서는 대용량 전지를 필요로 하여 Single stack으로는 사용되기 어렵고, Multi stack으로 주로 사용한다. Multi stack의 경우, 수 백장의 BP가 들어가 전지의 부피가 매우 커지게 되고, 이에 본 연구에서는 BP의 두꺼운 Graphite를 얇은 $TiO_2$ 기판으로 교체하여 성능을 비교하는 연구를 진행하였다. Ti 금속기판을 양극산화법으로 $TiO_2$ 나노튜브 구조를 만든 후, $TiO_2$의 전도도 향상을 목적으로 $IrO_2$를 코팅하였다. 결과적으로 기존의 Graphite에 비해 전기화학적 특성이 향상되었음을 확인하였으며, Cell test를 통해 VRFB의 성능을 평가하였다.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제22권11호
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• pp.547-558
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• 2016

다양한 ICT 인프라 기술들을 종합적으로 활용하는 클라우드의 대표적인 오픈소스 프로젝트인 오픈스택을 활용하여 멀티사이트 기반의 클라우드 인프라 구축 시 설치 복잡성 및 지리적인 제약으로 인한 인적, 시간적인 비효율성을 내포한다. 이러한 비효율성을 해소하기 위해 멀티사이트 환경의 오픈스택 실증 테스트베드인 OF@KOREN SmartX 놀이터 (Playground)를 대상으로 리눅스 및 오픈스택을 설치/설정을 자동화하는 도구를 데브옵스 (DevOps) 개발 방법론에 따라 점진적으로 개발해왔다. 하지만 이전 개발도구들이 고정된 형태의 프로비저닝만을 제공한다는 한계를 해결하고자 본 논문에서는 소프트웨어 정의 인프라의 자원관리 구도에 따라 자동 설치/설정도구를 엮어 Playground 수준의 프로비저닝을 수행하는 SmartX 프로비저닝 프레임워크의 프로토타입을 설계, 개발한다. 그리고 멀티사이트 오픈스택 클라우드를 자동으로 구축하는 과정을 제시함으로써 프레임워크의 효율적인 놀이터 프로비저닝 기능에 대해 검증한다.

• 한국정보과학회논문지:시스템및이론
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• 제34권11호
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• pp.572-580
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• 2007

무선 센서 네트워크는 자연 환경의 정보를 수집하고, 수집한 정보를 가공하고, 가공된 정보를 무선 통신을 통하여 사용자에게 실시간으로 전달하는 기능을 가진 설비이다. 이러한 센서 네트워크는 다수의 무선 센서 노드들로 이루어지고, 이 센서 노드들은 비용 효율성의 이유로 매우 제한적인 하드웨어 칩들로 구성된다. 예를 들어, UC Berkeley에서 설계한 MICA센서 노드에는 8-bit CPU, 4KB RAM, 그리고, 128KB FLASH 등으로 구성된다. 따라서 이것들을 동작시키는 센서 운영체제는 이러한 하드웨어 제약성을 감내할 수 있어야 한다. 본 논문에서는 멀티 쓰레디드 센서 운영체제를 위한 공간 효율적인 쓰레드 스택 관리 기법을 제안한다. 제안한 기법은 컴파일 시점에 각 쓰레드 함수의 스택 사용량 정보를 측정한다. 측정된 결과를 바탕으로, 함수 호출 시와 같은 스택 영역의 요구가 발생할 경우에 스택의 할당 및 반환 작업을 수행하여 쓰레드 스택 영역을 동적으로 관리한다. 본 기법은 나노 Qplus 센서 운영체제에서 구현되었다. 본 논문의 성능 실험을 통하여, 제안한 기법을 사용하는 것이 기존의 정적인 스택 관리 방법을 사용하는 것 보다 스택 메모리 공간을 보다 효율적으로 관리할 수 있음을 확인한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.541-544
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• 2005

This study presents the integrated modeling approach to simulate the proton exchange membrane (PEM) fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cel1 system, multi-variable optimization code was adopted. Using this method the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study tan be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.