• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.345-348
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• 2008

Metallic bipolar plate for molten carbonate fuel cell(MCFC) is composed of the shielded slot plate and the center plate. Among these, the center plate plays an important role in gas sealing. Therefore, manufacturing of the center plate is considered one of the key issues in MCFC. The center plate is manufactured by bending process. In bending process, springback and recoiling are two main problems. The aim of this article is to optimize the bending process of the center plate regardless of springback and recoiling. To achieve this goal, we proposed the punch having step to reduce springback and recoiling. Using finite element method and $L_9$ orthogonal array, we determined the main factors in the center plate bending process. And we found the optimal bending process condition for the MCFC center plate.

• Korean Chemical Engineering Research
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• 제60권2호
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• pp.277-281
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• 2022

The wetting dynamics of water droplets dispensed on the surface of dry and wet hydrophilic membranes were investigated experimentally from a microscale point of view. By using a high-speed, white-beam x-ray microimaging (WXMI) synchrotron, consecutive images displaying the dynamic motions of the droplets were acquired. Through analyzing the characteristics observed, it was found that the dry hydrophilic membrane showed local hydrophobicity at a certain point during the absorption process with apparent contact angles greater than 90. While on the other hand, the apparent contact angles of a water droplet absorbing into the wet membrane remained less than 90 and showed total hydrophilicity. The observations and interpretation of characteristics that affect the contact, wetting, recoiling, and dynamic behaviors of droplets are significant for controlling liquid droplet impingement in a desired manner.

• 수산해양기술연구
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• 제26권2호
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• pp.118-124
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• 1990

PP 로프의 유연도와 모릿줄이 사려지는 현상등을 기초적으로 조사한 다음, 반원형 안내판의 회전중심이 편심되도록 고달이채기 레버를 회전시켜 고달이를 자동으로 채어서 이송벨트에 정리하면서, 모릿줄이 고르게 사려지도록 줄받이의 왕복 회전장치 등을 제작하여 실험실과 통발어선에서 시험한 결과는 다음과 같다. 1. 직경 10mm의 PP 연심 모릿줄이 양승풀리에서부터 사려질 때 한 코일의 최소직경은 14cm 정도, 줄더미의 직경은 60cm 정도였다. 2. 소형 고달이채기에서 이송벨트의 상, 하 10cm이내에 분포하는 고달이의 비율은, 납이 1개 있는 모릿줄에서는 93%정도이나 납이 없는 모릿줄에서는 98%이상이었다. 3. 감속비가 3:1인 소형 고달이채기에서 레버의 회전수 N 하(1) (rpm)과 양승풀리의 회전수 N 하(p) (rpm)와의 관계는 N 하(p) =2.86N 하(1) +23.74 이며, 양승속도에 대한 고달이의 수평최대 이동속도의 비는 70%정도였다. 4. 보조양승기와 고달이채기를 연계시켜 줄받이를 상, 하로 왕복시킬 경우 모릿줄은 길이 방향으로 고루 사릴 수 있었으며, 고달이채기 레버의 회전과 줄받이의 왕복운동 주기는 고달이의 간격에 따라 조절할 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.1088-1092
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• 1996

This paper represents how a muzzle brake affects the dynamic characteristics of the recoil system. A muzzle brake is a device attached to the muzzle for the express purpose of diverting the propellant gas stream from its original path, thereby creating a foreward thrust on the recoiling gun which is in opposition to its rearward motion. In order to obtain the full advantage of a muzzle brake, it is necessary that the recoil system of a gun be designed for the purpose.

• 소성∙가공
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• 제11권3호
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• pp.246-254
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• 2002

A simple method to derive an optimal pressure curve, characterized by initial pressure, final pressure and pressure path, has been proposed. The initial pressure has been determined from the condition to prevent recoiling phenomenon in the early stage, while the final pressure is from the FE analysis and pressure path is from the punch penetration volume. In order to realize the pressure curve, an open loop control system based on a proportional relief valve has been developed for the renovated CNC hydroforming press. Through the comparison of experiment and analysis, the predicted pressure curve has been verified optimal curve since no defect has been observed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.220-223
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• 2009

Metallic bipolar plate for molten carbonate fuel cell(MCFC) is composed of the shielded slot plate and the center plate. Among these, the center plate plays an important role in gas sealing. Therefore, manufacturing of the center plate is considered one of the key issues in MCFC. The center plate is manufactured by bending process. In bending process, springback and recoiling are two main problems. By using the modified punch shape with 'step', springback and recoil are reduced. The aim of this article is to find the effect of modified punch shape. So, the bending stress along thickness direction and material direction were investigated using FEM.

• Korean Chemical Engineering Research
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• 제59권2호
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• pp.247-253
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• 2021

Electrocoalescence is an active technique in petroleum industry, formation of raindrop in cloud, and digital microfluidics. In the present work, electrocoalescence of two droplets under the constant electric potential in air was studied. Through this experiment, we found that the electrocoalescence process could be divided three phases; deformation, formation of liquid bridge, and merging. And the condition for formation of liquid bridge between two droplets was obtained. For the connection of experimental result in constant potential condition with general case in constant charge condition, relationship of charge and potential difference was deduced by numerical computation. In high electric potential case, flat interfaces after recoiling were observed. It was interpreted through a numerical simulation of electric field.

• 천문학회보
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• 제46권1호
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• pp.31.1-31.1
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• 2021

We report the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) observation of a red active galactic nucleus (AGN), 2MASSJ165939.7+183436 (1659+1834). 1659+1834 is a prospective merging supermassive black hole (SMBH) candidate due to its merging features and double-peaked broad emission lines. The double-peaked broad emission lines are kinematically separated by 3000 km/s, with the SMBH of each component weighing at 10^8.9 and 10^7.1 solar mass. Our GMOS IFU observation reveals that the two components of the double-peaked broad emission line are spatially separated by 0.085" (~250pc). In different assumptions for the line fitting, however, a null (<0.05") or a larger spatial separation (~0.15") are also possible. For this GMOS IFU observational results of 1659+1834, various models can be viable solutions, such as the disk emitter and multiple SMBH models. We believe that these results show the need for future research of finding more multiple SMBH systems in red AGNs.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.9-14
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• 2011

Due to the improvement of science technology, the future tank system will have the multi-function for more powerful firing. and the tank, mounted this multi-function, must be lighter to maintain the mobility. Therefore, new brecoil technology would be necessary to reduce the recoil force for lighter platform. The present study covers a FOOB(Fire-Out0-Of-Battery) system that can reduce the recoil force dramatically. The firing sequence of the FOOB system is radically different from that of a conventional system. The gun is latched in out-of-battery position prior to firing. As soon as firing is occurred, the gun is unlatched and accelerated. The forward momentum is imparted to the recoiling parts. This momentum is opposed by the ballistic force imparted by firing and the recoil force and recoil length will be reduced. In this study, the ADAMS simulation has been performed with the scale model of the FIB(Fire-In-Battery) system and the FOOB system. The ADAMS simulation results show that the FOOB system could reduce the operating time and recoil length and the recoil force.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.976-981
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• 2010

A soft-recoil or FOOB (Fire-Out-Of-Battery) system can reduce the recoil force considerably. Its firing sequency is different from that of a conventional or FIB (Fire-In-Battery) system. In FOOB system, the gun is latched and preloaded in its battery position prior to firing. When unlatched, the gun is accelerated to the forward direction and then the forward momentum of the recoil part is generated. Since this momentum reduces the recoil impulse, the recoil force will decrease significantly. When designing the soft-recoil system it is important to design the forward momentum profile of a recoiling part. In the present study, the method to determine the forward momentum has been studied and its optimum value has been obtained theoretically. The numerical simulation of the soft-recoil system is performed to show that the present soft-recoil system works functionally well.