• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.491-492
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• 2010

기존에 사용중인 저압용 벤튜리 타입 혼합기는 0.32kg/cm2에서 열리고 0.28kg/cm2에서 닫히도록 설정되어 있다. 이 방식은 증가하는 도시가스 공급량을 따라갈 수 없기 때문에 강제 혼합기를 개발 현장에 적용하고자 한다. 본 연구를 통해서 개발하고자하는 강제 혼합기는 제어밸브을 통하여 가스 62.5%, 압축공기 37.5%의 비율로 희석하여 서지탱크로 보내진다. 완성된 혼합기를 이용한 열량실험 결과 유량이 변하여도 일정한 열량이 나옴을 알 수 있었다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.22-24
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• 2020

본 논문은 11kW급 양방향 탑재형 충전기를 위한 CLLLC 공진 컨버터 설계에 대하여 발표한다. CLLLC 공진 컨버터의 공진 탱크 설계하였으며, 고효율화를 위하여 SiC-MOSFET을 사용하고, 배터리 전압에 따라 링크전압 가변 알고리즘과 동기정류기를 적용하였다. 그 결과를 바탕으로 프로토타입을 제작하여 실험한 결과를 발표한다.

• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.117-122
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• 2019

In the field of fluid dynamics, the sloshing effects are most common and significant problem. It is usually appeared in the tank filled with fluid which is on the main structure, thus, sloshing effects and its impact load may affect to entire system. For the sloshing effects analysis, impact loads due to tank motion is generally investigated theocratically, experimentally and numerically. The difficulty of sloshing phenomenon is non-linearity induced by large deformation at the free-surface. In this regard, it is well known issue that the repeatability on the sloshing problems is very low. In this study, moving particle semi-implicit method was employed to simulate sloshing problem and then the results were compared with corresponding experiments captured by high accuracy high speed camera. The results from numerical simulation was compared to experimental results.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.117-124
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• 2016

A C-type LNG mock-up tank was constructed to evaluate the durability of the tank and its structural safety. An experimental strain analysis system equipped with strain gages was designed to investigate the structural behavior of the inner tank at a high hydraulic pressure. In addition, the insulation used in the space between the inner tank and outer tank had a compressive strength and the inner tank thickness of the cylindrical shell and hemisphere was 4.0 mm, which was designed to be thinner than the existing rules. The strains on the inner tank were measured with increasing pressure, and these measurements were compared and analyzed at the strain gage attachment points.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.9
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• pp.74-80
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• 2009

This paper describes a $2{\sim}6GHz$ CMOS frequency synthesizer that employs only one LC-tank voltage controlled oscillator (VCO). For wide-band operation, optimized LO signal generator is used. The LC-tank VCO oscillating in $6{\sim}8GHz$ provides the required LO frequency by dividing and mixing the VCO output clocks appropriately. The frequency synthesizer is based on a fractional-N phase locked loop (PLL) employing third-order 1-1-1 MASH type sigma-delta modulator. Implemented in a $0.18{\mu}m$ CMOS technology, the frequency synthesizer occupies the area of $0.92mm^2$ with of-chip loop filter and consumes 36mW from a 1.8V supply. The PLL is completed in less than $8{\mu}s$. The phase noise is -110dBC/Hz at 1MHz offset from the carrier.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1995.06a
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• pp.54-64
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• 1995

대표적인 대형 베어링인 일체형 볼 베어링과 와기어 레이스형 볼 또는 로울러 베어링의 마찰 특성을 비성형 유한요소 프로그램인 MARC를 사용하여 상호간의 마찰형상에 대한 접촉응력과 마찰력 특성을 비교 해석하였다. 특히 와이어 레이스식 슬루잉 링 베어링은 우수한 마찰특성 때문에 건설기계, 하역기계, 광산기계나 탱크와 같은 국방무기 등에서 널리 사용되고 있다. 접촉면의 변형에 따른 일체형의 볼 베어링은 마찰력과 기울기면에서 와이어 레이스식 베어링에 비하여 크고, 같은 와이어 레이스식 베어링에서는 마찰력의 경우 볼 타입이 로울러 탕입에 비하여 약간 크게 나타났다. 이들의 계산결과를 종합하면 와이어 레이스식 베어링이 일체형 베어링에 비하여 마찰특성이 우수하고, 특히 와이어 레이스 베어링중에서 로울러 타입은 마찰 토오크면에서 균일하기 때문에 베어링을 사용한 제어기능 설계에서 특히 우수한 결과를 제공할 수 있다. 유한요소 해석결과는 기존의 실험결과와 잘 일치하고 있어서 슬루잉 링 베어링의 최적설계에 유한요소 해석의 유용함을 확인하였다. 또한 상부 구조물과 하부 구조물을 연결하기 위한 체결볼트의 구멍은 하중조건에 따라서 구조적 불안정성을 야기할 수 있음도 확인하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.529-537
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• 2021

Membrane-type hull and cargo holds have been designed and built for large ship. However, there is a growing interest in applying the same technology to small and medium-sized Liquefied natural gas(LNG) carriers to meet the recent increase in demand for LNG as an ecofriendly fuel and for expanding LNG bunkering infrastructure. The purpose of this study is to apply the IMO Type-B tank to small and medium-sized LNG carriers and verify the safety and suitability of the design. Fatigue crack propagation analysis was performed to install a partial second drip tray installed at the lower part of the LNG cargo tank by calculating the amount of leaked gas in the support structure supporting the cargo tank. First, a program for fatigue crack propagation analysis was developed, in which Paris' law and British Standard 7910 (BS 79110) were applied based on the International Code for the Construction of Equipment and Ships Carrying Liquefied Gases in Bulk, an international standard for LNG carriers. In addition, a surface crack propagation analysis was performed. Next, a methodology for assuming the initial through-crack size was developed to determine the size of the partial second barrier. The analysis was performed for 15 days, which is a possible return time after cracks are detected. Finally, the safety and suitability of the IMO Type-B for LNG cargo tanks required by international regulations were verified. For the accurate analysis of fatigue crack propagation, it is necessary to develop and verify the analysis procedure based on direct analysis and international regulations.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.165-168
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• 2007

The objective of this study is to demonstrate and commercialized for on-board fuel storage system for the hydrogen fuel cell vehicles. Type3 composite cylinder is consisting of the full wrapped composites on a seamless aluminum liner. Especially, the seamless aluminum liner has been commercialized with development of fabrication through this study. The key technologies, including design, analysis and the optimized filament winding process for 350bar composite cylinder, were established and verified with design qualification test in accordance with international standard. And the facilities for fabrication and design qualification test have been constructed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.457-464
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• 2010

Representative methods for removing spilled oil include mechanical skimming, chemical treatment, burning at the surface of the spilled oil, and microbiological degradation. Among these methods, mechanical skimmer is the most efficient. Mechanical skimming can be classified into the following categories: belt-type, disk-type, weir-type, drum-type. We designed models with a submerged orifice for use in our experiments, for an objective and systematic evaluation of the recovery efficiency of mechanical skimming. Basically, oil is lighter than seawater and hence tends to float on the surface of the latter if there is sufficient time for floating. The present skimmer is kind of wear-type with the submerged orifice for seawater to be squeezed through, minimizing water content in the tank. From the experimental results, we identify the parameters that influence the oil recovery rate and recovery efficiency. The recovery efficiency can be enhanced by increasing the thickness of the oil layer in the first oil accumulative tank.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.5
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• pp.380-387
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• 2016

Present research target to develop the procedure of long-term fatigue analysis of the structural details near the upper rolling chock of IMO type B tank by using the time domain modal analysis technique where both the contact and friction behavior can be accurately simulated. In order to perform the time domain analysis focused on the contact and friction, the entire model of the hull and tank was condensed with DOF reduction technique, which is obtained by transforming the global finite element model into its quasi-static modal coordinate. Modal analysis using the quasi-static deformation modes is chosen as a cost effective time domain simulation method and this is based on the fact that the structural response of the tank is quasi-static. Based on the developed cost effective time domain simulation method, the long-term fatigue analysis procedure for the structural details near the rolling chock and key of independent type tank is targeted to be established. The developed fatigue assessment procedure takes into account, wave induced stress and both contact and friction induced stress without loss of accuracy.