• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1149-1156
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• 2008

The principle of self clamping friction clutch is presented in this paper and the transmitted torque capacity is also calculated. In order to enlarge the friction force, a part of rotating force of driving side is converted to normal force of friction materials by clamping arm. The increased normal force of friction materials assures the large friction force and the transmitted torque capacity of clutch becomes large. The self clamping friction clutch is adopted in the tube type air pressure clutch and the condition of stability is investigated. It is proven that the inclined angle of clamping arm and the friction factor of friction materials are the essential elements in stability and torque capacity of self clamping friction clutch. The transmitted torque capacity of self clamping friction clutch is compared with air pressure clutch. The normal force of friction lining is magnified by 1/(1-k) and the transmitted torque capacity is also magnified with same proportion comparing with air pressure clutch. The larger the friction factor of friction lining, the larger the magnification factor. The longer the clamping arm, the smaller the magnification factor. It must be also noted that the value of k=${\mu}Y/X$ is the criterion of stability. If the value of k=${\mu}Y/X$ is greater than or equal to 1, the self clamping friction clutch is unstable and it can not be used as clutch.

• 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.

• The Korean Journal of Ceramics
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• 제5권1호
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• pp.87-90
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• 1999

It was suggested that tape casting method can be used to fabricate high-temperature electrostatic chucks(HTESC) based on a metal substrate coated with a glass-ceramic insulating layer. The adhesion of the coating was excellent such that it was able to withstand temperature cycling to over $300^{\circ}C$ without spalling. The electrostatic clamping pressure reached a very high value of about 9 torr at 600V and generally followed the theoretical voltage-squared curve. Based on these results, we believe that we successfully developed a viable technique for manufacturing low cost HTESC.

• 한국해양공학회지
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• 제17권4호
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• pp.37-42
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• 2003

The mechanical components with high-pressure hoses are generally produced by the swaging process. The hoses are composed of the rubber materials and the reinforced braids to support tensile forces. In case they are subjected to high mechanical and thermal loads under severe operating conditions, the oil in hoses can leak at the parts of small clamping forces. In this paper, the deformation characteristics of a fiber-reinforced hose are analyzed with respect to the jaw strokes using the finite element method. The manufacturing process is modeled with a contact problem in consideration of a real situation, and the material properties based on the experimental results are used in the analysis. Examinations of the relationship between the swaging strokes and the deformation behaviors of the hose were made on the basis of the stress and strain values of the hose components. The relations between clamping forces and separating forces are also proposed, in order to estimate clamping forces corresponding to separating forces for the given model.

• 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.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.521-528
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• 2018

전투목적으로 개발된 군용차량은 타이어 압력이 손실되더라도 일정시간동안 일정거리를 달릴 수 있도록 런플랫시스템을 도입하였다. 런플랫을 적용하기 위하여 휠을 외측림과 내측림으로 구성된 2개의 부분으로 구성하고, 클램핑 볼트를 체결함으로써 외측림과 내측림을 조립한다. 이 클램핑 볼트는 휠의 내구성을 결정하는 중요 부품이다. 실제로 휠의 내측림과 외측림의 파손보다는 클램핑볼트의 파손이 발생되어 휠을 사용하지 못하는 빈도가 높다. 따라서, 클램핑 볼트의 내구성능이 휠의 내구성능과 연관이 크다고 할 수 있다. 본 연구는 휠의 내구성을 향상시키기 위하여 휠조립체를 시험하고 클램핑 볼트를 개발하는 과정을 다루었다. 기존에 정립된 내구시험 조건의 불충분성을 식별하였으며, 휠조립체의 내구성을 보다 정확히 확인할 수 있도록 통제해야 하는 시험조건을 제시하였다. 정립된 시험조건을 기반으로, 성능이 개선된 클램핑 볼트를 시험하였다. 시험조건을 확인한 결과 기존 제품보다 최소 168% 내구성이 향상됨을 확인할 수 있었다. 본 연구는 휠 조립체의 내구시험 방법과 클램핑 볼트를 개발하는 과정에서 고려해야 할 요소를 제시한 것에 의미가 있다 할 수 있다.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.1-6
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• 2024

상용차용 수소 전기 차량 수요가 증가하면서 고분자 전해질 연료전지 (PEMFC) 내구성은 승용차용보다 5배 이상 증가해야 하므로 내구성 향상 연구개발이 시급한 상황이다. PEMFC 막전극접합체 (MEA)가 화학적 열화가 진행되면 MEA 두께가 감소하고 핀홀이 발생하기도 한다. 본 연구에서는 화학적 열화 가속 실험인 개회로전압 (OCV) holding 후에 단위전지의 체결압을 상승시키면서 MEA의 성능 및 내구성의 변화를 측정하였다. 체결압이 상승하면서 고분자막의 저항과 막/전극 접촉저항이 감소하여 I-V 성능이 향상되었고, 수소투과도가 감소하였다. 수소투과도 감소에 따라 OCV는 증가하였다. 핀홀 부위를 제거하고 MEA 체결압을 증가시켰을 때 수소투과도가 급감하여 국부적인 열화가 전체 셀의 성능과 내구성에 미치는 영향이 큼을 확인하였다. 핀홀 부위 제거 후 재체결하고 OCV holding 평가를 하였을 때 막 저항과 수소투과도 감소에 따라 내구성이 향상됨을 확인하였다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.169-172
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• 2002

This study demonstrated the feasibility of using tape-casting followed by sintering as a low-cost alternative for coating glass-ceramic or glass film on a metal substrate. The process has been successfully used to fabricate a glass-on-stainless steel and a glass-ceramic-on-molybdenum electrostatic chuck(ESC) with the insulating layer thickness about $150{\mu}{\textrm}{m}$. Electrical resistivity data of the coaling were obtained between room temperature and 55$0^{\circ}C$; although the resistivity values dropped rapidly with increasing temperature in both coatings, the glass-ceramic still retained a high value of $10^{10}$ ohm-cm at $500^{\circ}C$. Clamping pressure measurements were done using a mechanical apparatus equipped with a load-cell at temperatures up to $350^{\circ}C$ and applied voltages up to 600V; the clamping behavior of all ESCs generally followed the voltage-squared curve as predicted by theory. Based on these results, we believe that we have a viable technology for manufacturing ESCs for use in reactive-ion etch systems.

• Design & Manufacturing
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• 제15권1호
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• pp.1-7
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• 2021

The position of the gate is one of the important factors for optimal injection molding. This is because inappropriate gate positions cannot fill the cavity uniformly, which can lead to defects such as contraction. In this study, CAE was performed on hot runner injection molding of the washing machine base and plasticity was compared by changing gate position from existing gate position. A total of two alternatives have been applied to compare the plasticity of the washing machine base according to its optimal gate position. The gate position of the improved molds and the gate position of the current mold is analyzed by injection molding analysis. The results of the fill time, the pressure at V/P switchover, clamping force, and deflection were compared. In washing machine base injection molding, the deflection was reduced by about 3.76% in the improved mold 2. In improved mold 1, the fill time during injection molding was reduced by 3.32% to enable uniform charging, and the clamping force was reduced by 31.24%. We have confirmed that the position of the gate can change the charging pressure and the clamping force and affect the quality and cost savings of the molded product.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 추계학술대회 논문집
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• pp.247-252
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• 2005

쐐기형 레일클램프는 작은 초기 압착력으로 레일을 압착한 후 풍속이 증가함에 따라 쐐기작용에 의해 압착력이 증가하여 레일을 강하게 압착하는 구조를 가지고 있다. 쐐기형 레일클램프를 설계하기 위해서는 쐐기작용을 위한 적정 쐐기각과 초기압착력 발휘를 위한 적정 Locker의 물림각을 결정해야 한다. 적정 쐐기각에 관한 연구는 이미 수행되었으며, 본 연구에서는 Locker의 적정 물림각을 설정하기 위하여 이전 연구를 바탕으로 $10^{\circ}$의 쐐기각을 갖는 레일클램프에서 Locker의 물림각과 Jaw pad의 압착력 사이의 상관관계를 실험적 분석을 통해 살펴보았다. 레일클램프의 초기 압착력은 Locker의 물림각에 의해 결정되므로 3, 4, 5, $6^{\circ}$의 4가지 Locker의 물림각에 따른 Locker의 물림력을 압력게이지를 이용하여 측정한 후 Jaw pad의 압착력을 산출하여 유한요소해석결과와 비교하였다.