• 한국환경보건학회지
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• 제46권5호
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• pp.555-564
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• 2020

Objectives: To identify and investigate through qualitative and quantitative analysis the hazardous substances generated when compressed wood was burned at a live fire-training center. Methods: Four types of compressed wood that are actually used in live fire training were burned in a chamber according to KS F2271. The gaseous material was sampled with a gas detector tube and conventional personal samplers. Results: 1,3-butadiene, benzene, toluene, xylene, formaldehyde, hydrogen chloride, hydrogen cyanide, ammonia, carbon monoxide, and nitric acid were detected. In particular, 1,3-butadiene (497.04-680.44 ppm), benzene (97.79-125.02 ppm), formaldehyde (1.72-13.03 ppm), hydrogen chloride (4.71-15.66 ppm), hydrogen cyanide (3.64-8.57 ppm), and sulfuric acid (3.85-5.01 ppm) exceeded the Korean Occupational Exposure Limit as measured by sampling pump according to the type of compressed wood. Conclusions: We found through the chamber testing that firefighters could be exposed to toxic substances during live fire training. Therefore, firefighter protection is needed and more research is required in the field.

• 한국가스학회지
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• 제24권5호
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• pp.74-81
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• 2020

일반적으로 반도체를 제조할 때는 인화성, 독성, 부식성의 유해·위험물질이 다수 사용되며, 특히 화학적 증착(CVD), 식각(Etch) 등의 공정에서는 특수가스를 사용하여 반도체를 제조하고 있다. 특수가스는 압축 또는 액화가스의 상태로 용기에 충전되어 있는데, 특수가스를 반도체 제조공정에 공급하는 설비로서 가스캐비닛(Gas Cylinder Cabinet)이 사용되고 있다. 이러한 가스공급시스템 내에서 실린더 이상 발생 시 배관·계측기 등 공급시스템의 안전 확보를 위해 가스실린더에 설치된 압력방출장치를 통해 가스가 방출하게 되는데, 이 경우 가스캐비닛 내부에 방출되는 가스가 캐비닛 외부로 누출될 위험성이 존재한다. 따라서 가스캐비닛 내부의 유체유동을 분석하여 누출에 따른 위험성을 파악하고 이에 대한 위험도 감소를 위한 대책을 제시하고자 한다.

• 한국산학기술학회논문지
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• 제10권4호
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• pp.695-701
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• 2009

고압의 가스를 이용하여 고온 가스와 저온 가스를 분리하거나 입자상 물질의 분리에 사용 할 수 있는 장치인 볼텍스 튜브의 에너지 분리 특성을 적용하여 $CO_2$ 흡수를 위한 장치설계의 기본 설계 자료를 구축하기 위하여 전산유체 해석을 수행하였다. 설계를 위한 기초 자료를 확보하기 위하여, 볼텍스 튜브의 길이, 볼텍스 발생기의 오리피스 직경 및 고온 측과 저온 측의 유량비등이 볼텍스 튜브의 성능에 미치는 영향을 분석하였다. 튜브의 길이가 길어짐에 따라 고온 출구측의 온도는 감소하지만, 저온 출구측의 온도에 미치는 영향은 미미하였다. 볼텍스 발생기의 오리피스 직경이 축소됨에 따라 저온측 온도는 강하하나 고온측 온도의 변화는 미미하였다. 고온 유량비가 증가함에 따라 고온 출구 쪽의 온도가 강하하였다. 본 연구의 결과는 $CO_2$ 흡수 장치의 기본 설계 자료로 응용될 수 있을 것이다.

• 대한기계학회논문집A
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• 제35권4호
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• pp.439-445
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• 2011

대기오염 등 환경에 대한 관심이 높아지면서 경유차 배출 가스 저감을 위한 최적의 대안으로 최근 세계적으로 천연가스차량의 보급이 크게 확대되고 있는 추세이다. 이러한 추세에도 불구하고 그 안전성에 대해서는 많은 논란을 불러 일으키고 있으며 최근 그 이용에 따른 안전사고 또한 빈번하게 발생하고 있다. 천연가스버스 압력용기 파열 사고는 대중들이 많이 이용한다는 점에서 대형참사로 이어질 수 있는 잠재력을 가지고 있어 그 심각성은 매우 크다고 할 수 있다. 이에 법공학적인 측면에서 좀 더 전문화되고 체계적인 사고조사와 원인 규명을 통해서 사전에 예방대책을 마련함으로써 유사 및 동종재해의 발생을 최소화해야 한다. 본 연구에서는 구조해석을 통한 용기의 설계 검증과 용기의 파손형태 검사 및 재료 물성평가 등을 통해 용기파손에 의한 CNG 차량 폭발 사고에 관한 정확한 사고 원인을 규명함으로써 동일 형태의 차량 안전사고 예방에 기여하고자 한다.

• 한국수소및신에너지학회논문집
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• 제20권6호
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• pp.499-504
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• 2009

The effect of gas diffusion layer (GDL) compression caused by different stack clamping pressures on fuel cell performance was experimentally studied in a miniature 5-cell proton exchange membrane fuel cell (PEMFC) stack. Three stacks with different GDL compressions, 15%, 35% and 50%, were prepared using SGL 10BC carbon fiber felt GDL and Gore 57 series MEA. The PEMFC stack performance and the stack stability were enhanced with increasing stack clamping pressure resulting in the best performance and stability for the stack with higher GDL compressions up to 50%. The excellent performance of the stack with high GDL compression was mainly due to the reduced contact resistance between GDL and bipolar plate in the stack, while reduced gas permeability of the excessively compressed GDL in the stack hardly affected the stack performance. The high stack clamping pressure also resulted in excessive GDL compression under the rib areas of bipolar plate and large GDL intrusion into the channels of the plate, which reduced the by-pass flow in the channels and increase gas pressure drop in the stack. It seems that these phenomena in the highly compressed stack enhance the water management in the stack and lead to the high stack stability.

• Tribology and Lubricants
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• 제22권6호
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• pp.329-334
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• 2006

In CNG (Compressed natural gas) fuel supply line, whose main components are receptacle and check valve are used to charge high pressure gas to the tank of NGV (Natural gas vehicle). It is reported that the seal is separated occasionally form valve seat and results in blockage of gas flow. In this paper, MARC is used to investigate the reasons of seal separation and suggest design improvements. The static gas pressure distributions acting on the seal which calculated using FLUENT are considered to investigate accurate seal deformation behaviors. Deformed seal shapes are obtained for various amounts of seal interference and its location, gas pressure distributions and Young's modulus of the rubber used. The results showed that the reasons of seal separation problems are verified theoretically, and suggested examples of new design method. Therefore the present numerical methods can be applied in designing and performance analysis of rubber seals adopted in high pressure fluid machineries.

• 드라이브 ㆍ 컨트롤
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• 제12권4호
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• pp.35-40
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• 2015

A gas spring provides support force for lifting, positioning, lowering, and counterbalancing weights. It offers a wide range of reaction force with a flat force characteristic, simple mounting, compact size, speed controlled damping, and cushioned end motion. The most common usage is as a support on a horizontally hinged automotive tail gate. However, its versatility and ease of use has been applied in many other industrial applications ranging from office equipment to off-road vehicles. The cylinder of a gas spring is filled with compressed nitrogen gas, which is applied with equal pressure on both sides of the piston. The surface area of the rod side of the piston is smaller than the opposite side, producing a pushing force. The magnitude of the reaction force is determined by the cross-sectional area of the piston rod and the internal pressure inside the cylinder. The reaction force is influenced by many design parameters such as initial chamber volume, diameter ratio, etc. In this paper, we investigated the reaction force characteristics and carried out parameter sensitivity analysis for the design parameters of a gas spring.

• 한국생산제조학회지
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• 제21권1호
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• pp.1-6
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• 2012

This paper presents a stress safety of a composite pressure cylinder for a hydrogen gas vehicle. The composite pressure cylinder in which is composed of an aluminum liner and carbon fiber wound layers contains 104 liter hydrogen gas, and is compressed by a filling pressure of 70 MPa. The FEM computed results are analyzed based on the US DOT-CFFC basic requirement for a hydrogen gas cylinder and KS B ISO specification. The FEM results indicate that the stress, 255.2 MPa of an aluminum liner is sufficiently low compared with that of 272 MPa, which is 95% level of a yield stress for aluminum. Also, the composite layers in which are wound on the surface of an aluminum cylinder are safe because the stress ratios from 3.46 to 3.57 in hoop and helical directions are above 2.4 for a minimum safety level. The proposed composite pressure cylinder wound by carbon fibers is useful for 70 MPa hydrogen gas vehicles.

• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.45-50
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• 2017

The gas spring is a hydropneumatic adjusting element, consisting of a pressure tube, a piston rod, a piston and a connection fitting. The gas spring is filled with compressed nitrogen within the cylinder. The filling pressure acts on both sides of the piston and because of area difference it produces an extension force. Therefore, a gas spring is similar in function compare to mechanical coil spring. Conversely, optimization is a process of finding the best set of parameters to reach a goal while not violating certain constraints. The AMESim software provides NLPQL (Nonlinear Programming by Quadratic Lagrangian) and GA (genetic algorithm) for optimization. The NLPQL method builds a quadratic approximation to the Lagrange function and linear approximations to all output constraints at each iteration, starting with the identity matrix for the Hessian of the Lagrangian, and gradually updating it using the BFGS method. On each iteration, a quadratic programming problem is solved to find an improved design until the final convergence to the optimum design. In this study, we conducted optimization design of the gas spring reaction force with NLPQL.

• 동력기계공학회지
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• 제22권6호
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• pp.74-79
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• 2018

Compressed natural gas has a high octane number and low particulate emission characteristics as compared with petroleum-based fuels, so it can respond to exhaust gas regulations positively. A natural gas engine has been introduced to improve the quality of the atmosphere, a diversity of fuel, a stable supply, and it has widely been used in city buses and garbage trucks. Recently, the natural gas engine has received attention by overcoming the disadvantage of the theoretical air-fuel ratio method through the development of EGR cooler and engine parts with the development of LP-EGR technology. In this study, we try to develop the cogeneration system that can simultaneously generate electric power and heat by remodeling the gasoline engine to the mixer type CNG engine. As a result, it was able to reduce the NOx (approximately 77%) compared to the diesel engines with same displacement.