• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.374-377
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• 2005

Hyundai motor company has designed a above 50kW-class PEMFC stack for Fuelcell vehicle based on SUV. Hyundai increased the power density of the stack through the optimized flowfield of bipolar plate, manifold structure, and improvement of sealing, etc. Also, Gas to Gas humidifier was adopted in fuelcell system to reduce the system humidification load, it had been proven by short stack test. Components of stack, bilpolar plate, manifold, were analyzed through the computer simulation, so temperature and pressure distribution in the components and system were improved. This stack tested in Bread Board which was organized similar to real vehicle system.

• 설비공학논문집
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• 제16권9호
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• pp.796-803
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• 2004

The stack effect of a new type condenser installed in a high-rise apartment building was studied numerically A sirocco fan is introduced to the new type condenser instead of an axial flow In. The new type condenser intakes the cold air through the lower inlet and exhausts the hot air through the upper outlet. The effects of the building height and frontal wind on the performance of an air-conditioner were analyzed. The performance of an air-conditioner was evaluated by using COP (coefficient of performance) and CGPI (condenser group performance indicator). the hot air was exhausted by the new type condenser at an angle of 50$^{\circ}$ from the outer wall of the building. If there was no draft, the new type condenser installed in the high-rise apartment building had a good performance and its performance on each floor is not influenced by the stack effect. It is shown that the efficiency of the air-conditioner installed in several floors below the top floor decreased when the frontal wind velocity was greater than 8 m/s.

• 한국세라믹학회지
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• 제44권8호
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• pp.407-411
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• 2007

A 3-cell stacked anode-supported solid oxide fuel cell was designed and fabricated to achieve a complete gas seal and the facile stacking of components. The stack was assembled with a unit cell with $10{\times}10cm^2$ area, and each cell was interconnected by a stainless steel 430 separator using a proprietary sealant sheet. The stack performance was examined at various gas flow rates of $H_2+3.5vol%\;H_2O$, and air at a fixed temperature of $800^{\circ}C$. No gas leakage was found from the sealing between cells and inter-connects within a measurement system in this research during a prolonged time of 500 h in operation. The test resulted in an open circuit voltage of 3.12 V, a peak power of 149 W, and a power density of $0.61W/cm^2$, while the long term durability of the power showed 19.1% degradation during the prolonged time of 500 h when tested at $800^{\circ}C$.

• 한국정보과학회논문지:시스템및이론
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• 제35권1호
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• pp.53-59
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• 2008

무선 센서 네트워크의 발달에 따라 그 응용분야는 점점 더 복잡해져 가고 있음에도 불구하고, 대부분의 센서 노드 플랫폼은 여전히 심각한 자원 제약을 가지고 있다. 특히 적은 메모리 공간과 메모리 관리 유닛(MMU)의 부재는 스레드의 스택 관리에 있어 메모리 공간 낭비, 스택 오버플로우와 같은 문제를 야기해왔다. 이에 다 수의 스레드가 하나의 스택을 공유 함으로써 기존의 고정 크기 스택에 의해 낭비되는 메모리의 양을 최소화 시킬 수 있는 공유 스택 기법이 제안되었다. 본 논문에서는, 고정 크기 스택기법과 공유 스택 기법의 수학적 분석 모델을 제시하였다. 그 모델을 바탕으로 각각의 스택 오버플로우 확률을 계산하고 공유 스택 기법이 고정 크기 스택보다 더 안정적임을 확인하였다.

• 설비공학논문집
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• 제21권12호
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• pp.703-714
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• 2009

One of the biggest problems in smoke control systems for high-rise buildings is stack effect, but there are no recognized methods or measures to solve the problem of stack effect as yet. The stack effect can be overcome by forming the uprising current inside the stair hall properly, but there is a limit to the height in supplying into the stair hall the smoke control air volume to be supplied to a floor in case of escape from fire. The limit to the height can be extended by over-coming the stack effect by pressurizing the stair hall and the ancillary room simultaneously. It can also be anticipated that the stack effect can be overcome by connecting the air supply shaft to the stair hall at the top. As a result of computer simulations using a network type of tool, it is found that adequate performance can be achieved by pressurizing the stair hall only for a building of 190m or less, and up to 360m when pressurizing the stair hall and the ancillary room simultaneously. In all those cases, however, an overpressure venting damper is required which operates within a suitable range for venting the overpressure outside.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.852-858
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• 2011

This paper is aiming to estimate the mutual influence of the stack cooling performances with the operation modes of the thermal management system for the hydrogen fuel cell vehicles. The heat capacity of the thermal management system was measured by varying the operating modes such as stack cooling heat exchanger only (Mode 1), stack cooling and electric devices cooling heat exchangers (Mode 2), and stack cooling and electric devices cooling heat exchangers with an operation of the condenser (Mode 3).As the results, Performance of the thermal management system (TMS) at Mode 3 decreased up to 34.0%, compared with the result of the Mode 1. In addition, in order to optimize the performance of TMS, the entropy change of stack cooling heat exchanger using irreversibility analysis technique was analyzed with the relationship between entropy generation and entering air velocity of the thermal management system.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.468-475
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• 2012

A proper stacking force and assembly are important to the performance of fuel cell. Improper assembly pressure may lead to leakage of fuels and high interfacial contact resistance, excessive assembly pressure may result in damage to the gas diffusion layer and other components. The pressure distribution of gas diffusion layer is important to make interfacial contact resistance less for stack performance. To analyze the influence of design parameter factors for pressure distribution, and to optimize stack design, DOE (Design of Experiment) was used for polymer electrolyte membrane fuel cell stack pressure test. As commonly known, the higher clamping force improves the fuel cell stack performance. However, non-uniformity of stress distribution is also increased. It shows that optimization between clamping force and stress distribution is needed for well designed structure of fuel cell stack. In this study, stack design optimization method is suggested by using FEM (Finite Element Methode) and DOE for light-weighted fuel cell stack.

• 전자공학회논문지
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• 제53권12호
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• pp.152-158
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• 2016

본 논문에서는 오픈소스 플랫폼 라즈베리파이 3 모델을 기반으로 몽고DB 데이터베이스를 활용하여 풀 스택 플랫폼을 구현하였다. 가속도 센서를 사용하여 무선 통신으로 데이터를 로깅하는 도구로써 이벤트 구동 방식을 사용하였으며, 리눅스 라즈비안 Jessie 버전으로 초당 28 프레임으로 USB 카메라(MS LifeCam 시네마) 이미지를 획득하며, 안드로이드 모바일 기기와 인터페이스를 구축하기 위하여 블루투스 통신 기술을 확장하였다. 따라서 본 논문에서는 가속도 센서 동작을 검출하여 이벤트 트리거링을 감지하는 풀 스택 플랫폼 기능을 구현하고, IoT 환경에서 온도와 습도 센서 데이터를 수집한다. 특히 몽고 DB가 MEAN 스택과 가장 좋은 데이터 연결성을 갖고 있기 때문에 풀 스택 플랫폼 성능을 개발 향상시키는데 MEAN 스택을 사용하였다. 향후 IoT 클라우드 환경에서 풀 스택 성능을 향상시키고, 몽고 DB를 활용하여 보다 쉽게 웹 설계 성능을 향상시키도록 기술을 개발하겠다.

• 디지털콘텐츠학회 논문지
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• 제12권4호
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• pp.551-557
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• 2011

본 논문에서는 안드로이드 2.3에서 어플리케이션 실행 시 가비지 컬렉션(garbage collection)으로 인하여 발생하는 성능 저하를 감소시키기 위한 자바(Java) 객체들의 스택 할당(stack allocation) 기법을 제안하였다. 제안한 스택 할당 기법에서는 자바 객체들을 가비지 컬렉션이 되는 힙(Heap) 영역 대신에 스택에 할당함으로써 실행 시 가비지 컬렉션 대상이 되지 않게 한다. 제안한 기법의 성능 검증을 위하여 실제 자바 벤치마크에서 널리 사용되고 있는 Caffeinemark 및 자체 벤치마크 어플리케이션을 통해 안드로이드 스마트 폰에서 비교 실험을 하였다. 그 결과 자바 객체들의 스택 할당에 따르는 동작상의 오버헤드로 인한 수행 속도의 저하는 미미함을 보이면서도 가비지 컬렉션 수행 빈도는 상당히 감소시켜 어플리케이션 동작 및 사용자 인터페이스 성능 향상을 가져왔다.

• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.341-348
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• 2016

The experiments related on structure and water electrolysis performance of HALE UAV stack were conducted in this study. Anode catalyst $IrRuO_2$ was prepared by Adam's fusion methods as 2~3 nm nano sized particles, and the cathode catalyst was used as commercial product of Premetek. The MEA (membrane electrode assembly) was manufactured by decal methods, anode and anode catalytic layers were prepared by electro-spray. HALE stack was composed of 5 multi-cells as $0.2Nm^3/hr$ hydrogen production rate with hydrogen pressure as 10 bar. The water electrolysis performance was investigated at atmospheric pressure and temperature of $55^{\circ}C$. Best performance of HALE UAV stack was recorded as cell voltage efficiency as 86%.