• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1881-1895
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• 2020

The theoretical aspects behind the reactor depletion capability of the Monte Carlo code MCS developed at the Ulsan National Institute of Science and Technology (UNIST) and practical results of this depletion feature for a Material-Testing Reactor (MTR) with plate-type fuel are described in this paper. A verification of MCS results is first performed against MCNP6 to confirm the suitability of MCS for the criticality and depletion analysis of the MTR. Then, the dependence of the effective neutron multiplication factor to the number of axial and radial depletion cells adopted in the fuel plates is performed with MCS in order to determine the minimum spatial segmentation of the fuel plates. Monte Carlo depletion results with 37,800 depletion cells are provided by MCS within acceptable calculation time and memory usage. The results show that at least 7 axial meshes per fuel plate are required to reach the same precision as the reference calculation whereas no significant differences are observed when modeling 1 or 10 radial meshes per fuel plate. This study demonstrates that MCS can address the need for Monte Carlo codes capable of providing reference solutions to complex reactor depletion problems with refined meshes for fuel management and research reactor applications.

• 항공우주시스템공학회지
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• 제11권6호
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• pp.34-41
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• 2017

기존 알루미늄 하니콤 코어를 이용한 착륙선 충격완충장치의 대체 방안으로서 실리콘 고무와 같은 초점탄성 재료의 다중압출 특성을 이용한 새로운 개념의 충격 완충장치를 고찰하였다. 초점탄성재료가 오리피스 단면을 통과하며 압출되는 과정에서 재료 변형에너지 및 하중-변위 특성이 기존 하니콤 코어 특성과 유사하여 충격 완충 성능을 극대화 할 수 있는 측면에서 유사성을 가지고 있음을 알 수 있었다. 본 논문에서는 충격완충장치의 설계 구현가능성을 평가하고, 에너지 변환을 통한 충격흡수 매커니즘을 이해하기 위하여 유한요소해석 및 준정적 압축시험 결과를 검토하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.203-206
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• 2001

A 30kw Dual rotor Turbines HAWT/VAWT combined wind turbine system that can drastically enhance the power production capability compared to conventional Single Rotor Turbine HAWT system. The combined system that takes advantage of strong point of both horizontal and vertical Axis wind turbine system developed by a venture firm KOWINTEC of Chonbuk national university. The HAWT/VAWT hybrid system has been successfully field tested and commercial operating since Feb. 12, 2001 in Hae-chang rest park, Bu-an county near the Sae Man-Kum Sea Dike. This paper will briefly describe the field test results performance and a special aerodynamic structure with bevel-planetary gear box of Dual Rotor Wind Turbine system.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.219-222
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• 1999

A method for numerical simulation of the carbonization process in manufacturing of a carbon-carbon composite is developed. A general theory, which consists of analyses of heat and mass transfer together with stress and displacement predictions, is constructed. A homogeneous, single phase, isotropic material is selected and a computer program is developed for an arbitrary 2-dimensional geometry using FEM. Material properties are obtained through experiments and references, and are modeled effectively to serve the simulation purpose. The validity of the simulation is verified through several comparisons with experimental data, where close agreements are observed. Finally, examples of actual applications are considered to exhibit the capability and utilization of the code in process optimization.

• 산업기술연구
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• 제23권A호
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• pp.21-27
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• 2003

The bio-micro pin is usually used for biochemistry analysis. The capability of manufacturing the micro-pin and array with effective and low-cost way is very important to developers. The micro-pin is composed of "sample channel" putting liquid into already fixed volume, "flat tip" having connection with printing quantity, and "head part" for preventing it from rotation of pin in the holder. We analyzed out printing variation in accordance with shape and tip size of the micro-pin point channel, In this study, we suggested the manufacturing progress and shape demand condition of the micro-pin which could put $0.2{\mu}{\ell}$-biochemistry material into the sample volume, and will be able to produce the micro-pin which can put $10n{\ell}$-biochemistry material into the sample volume in the future.

• 한국기계가공학회지
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• 제13권6호
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• pp.54-60
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• 2014

In industry, several casting process are widely used to manufacture complex and accurate blank part of hard materials such as aluminum, casting steels, bronze and magnesium alloys which are difficult to manufacture in a blank shape. Even if the casting process does not high accuracy superior surface characteristics other machining process, the casting process is widely used in manufacturing blank part. Furthermore, it is difficult to select appropriate casting process a part among several casting process. for effective selection different process, a careful decision given casting application is necessary. An appropriate casting for a given material and shape condition must be selected for novice engineers in industry. In this paper, an expert system based on an analytic network process(ANP) is suggested for best selection of casting considering a prior interdependency effect among various factors such as material, geometry, process capability, economy and equipment.

• 한국지반신소재학회논문집
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• 제12권1호
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• pp.83-92
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• 2013

지중송전관로를 통한 송전용량 증대를 위해서는 송전 시 발생하는 열을 빠르게 소산시킬 수 있도록 습윤 시 $50^{\circ}C$-cm/Watt, 건조 시 $100^{\circ}C$-cm/Watt 이하의 열 저항률을 갖는 재료를 되메움재로 사용하는 것이 요구되며, 이를 위해 선행연구에서는 요구되는 조건을 만족시키는 열 소산 되메움재를 개발하였다. 이 연구에서는 개발된 열 소산 되메움재의 열 소산효과를 알아보기 위하여 1회선의 단면을 현장에 설치하고 개발된 열 소산 되메움재와 강모래, 현장토에 대하여 열을 직접 가하고 일정한 지점에서 온도를 측정함으로서 현장시험을 수행하였고, 시험결과와 유한요소해석과의 비교를 통해 열 소산효과를 비교하였다. 비교결과, 열원과 가까운 지점에서는 개발된 열 소산 되메움재가 강모래와 현장토에 비해 열평형상태에 빨리 도달하는 것으로 나타났으며, 열평형에 도달하는 온도도 높은 것으로 나타나 열 소산효과가 우수한 것으로 나타났다. 또한 다른 지점에서도 개발된 되메움재가 다른 재료보다 온도가 높아 열 소산효과가 우수한 것으로 나타났다. 또한 함수비의 변화에도 열 소산효과가 크게 변화하지 않는 것으로 나타났다.

• Journal of Magnetics
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• 제20권1호
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• pp.86-90
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• 2015

Electromagnetic actuators are versatile and able to meet demanding requirements, such as operation in very low or very high temperatures. When the actuator is used in a high-temperature environment up to $500^{\circ}C$, we need to know how the force-producing capability of the actuator is affected by the operating temperature. Specifically, it is necessary to know the temperature-dependence of magnetic properties that determine the mechanical forces. In this paper, we measure the changes in magnetic properties of SUS410 material in high-temperature environment. We also devise a novel signal processing technique to remove the integration drift. At the field strength of 18,000 A/m, we found that the flux density at $500^{\circ}C$ is decreased by 26%, compared to the result at room temperature. Therefore, the actuator must be sized appropriately, if it is to operate in high-temperature settings.

• Composites Research
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• 제27권4호
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• pp.152-157
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• 2014

Non-destructive testing methods of composite materials are very important for improving material reliability and safety. AE measurement is based on the detection of microscopic surface movements from stress waves in a material during the fracture process. The examination of AE is a useful tool for the sensitive detection and location of active damage in polymer and composite materials. FBG (Fiber Bragg Grating) sensors have attracted much interest owing to the important advantages of optical fiber sensing. Compared to conventional electronic sensors, fiber-optical sensors are known for their high resolution and high accuracy. Furthermore, they offer important advantages such as immunity to electromagnetic interference, and electrically passive operation. In this paper, the crack detection capability of AE (Acoustic Emission) measurement was compared with that of an FBG sensor under tensile testing and buckling test of composite materials. The AE signals of the PVDF sensor were measured and an AE signal analyzer, which had a low pass filter and a resonance filter, was designed and fabricated. Also, the wavelength variation of the FBG sensor was measured and its strain was calculated. Calculated strains were compared with those determined by finite element analysis.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.150-151
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• 2006

$Si_{0.88}Ge_{0.12}$/Si heterostructure channels grown by RPCVD were employed to n-type metal oxide semiconductor field effect transistors(MOSFETs), and their electrical properties were investigated. SiGe nMOSFETs presented very high transconductance compared to conventional Si-bulk MOSFETs, regardless substantial drawbacks remaining in subthreshold-slope, $I_{off}$, and leakage current level. It looks worthwhile to utilize excellent transconductance properties into rf applications requesting high speed and amplification capability, although optimization works on both device structure and unit processes are necessary for enhanced isolation and reduced power dissipation.