• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3879-3891
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• 2021

A heat pipe residual heat removal system is proposed to be incorporated into the reactor driven subcritical (RDS) facility, which has been proposed by MIT Nuclear Reactor Laboratory for testing and demonstrating the Fluoride-salt-cooled High-temperature Reactor (FHR). It aims to reduce the risk of the system operation after the shutdown of the facility. One of the main components of the system is an air-cooled heat pipe heat exchanger. The alkali-metal high-temperature heat pipe was designed to meet the operation temperature and residual heat removal requirement of the facility. The heat pipe model developed in the previous work was adopted to simulate the designed heat pipe and assess the heat transport capability. 3D numerical simulation of the subcritical facility active zone was performed by the commercial CFD software STAR CCM + to investigate the operation characteristics of this proposed system. The thermal resistance network of the heat pipe was built and incorporated into the CFD model. The nominal condition, partial loss of air flow accident and partial heat pipe failure accident were simulated and analyzed. The results show that the residual heat removal system can provide sufficient cooling of the subcritical facility with a remarkable safety margin. The heat pipe can work under the recommended operation temperature range and the heat flux is below all thermal limits. The facility peak temperature is also lower than the safety limits.

• 항공우주기술
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• 제4권2호
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• pp.88-93
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• 2005

정지궤도 위성을 대상으로 각도 정보를 기반으로 하는 궤도결정 기술에 대한 개념 연구를 수행하였다. 정지궤도 위성의 관측 영역에 지구와 부근의 별이 동시에 촬영된다는 가정하에 지구와 별의 시야각 정보가 궤도결정의 입력으로 사용될 수 있음을 확인하였다. 최소자승법 알고리즘과 MATLAB을 사용한 시뮬레이션에서 그 수렴성을 확인할 수 있었다. 이러한 개념 연구의 대상 위성으로 통신해양기상위성을 가정하였다. 이러한 기술은 지상국의 궤도 결정의 보조 방법 또는 위성운용 자동화의 일부분으로 응용될 수 있을 것이다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.264-267
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• 2001

by three-dimensional finite element method. The guide roll is an intermediately supported trans-axle miler, so called I-STAR roll, which was designed by VAI. The guide roll has been used in POSCO since 1998. Though the number of stowage in casting has been apparently decreased since thef it has occasionally been failed during operation. The simulations were carried out to find out the status of stress and deformation as well as improvement of the guide roll. The thermal effect is much more dominant than ferro-static pressure or others in stress and deformation of the guide roll. The material of the guide roll is SCM440.

• 대한수학회지
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• 제48권1호
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• pp.191-205
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• 2011

It is well known that for a Krull domain R, the divisor class group of R is a torsion group if and only if every subintersection of R is a ring of quotients. Thus a natural question is that under what conditions, for a non-Krull domain R, every (t-)subintersection (resp., t-linked overring) of R is a ring of quotients or every (t-)subintersection (resp., t-linked overring) of R is at. To address this question, we introduce the notions of *-compact packedness and *-coprime packedness of (an ideal of) an integral domain R for a star operation * of finite character, mainly t or w. We also investigate the t-theoretic analogues of related results in the literature.

• 제어로봇시스템학회논문지
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• 제13권8호
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• pp.804-809
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• 2007

Initialization problem is defined for indoor mobile robot as a whole process from arrival to normal operation in a new environment. The unstructured environment make the process much more difficult compared to industrial robot in structured environments. We propose a simple and efficient initialization process based on artificial stars on ceiling. Important task points and paths connecting task points are defined based on the corresponding artificial stars. This approach can be used for all kinds of indoor mobile robots with landmarks used for indoor localization.

• Kyungpook Mathematical Journal
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• 제54권4호
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• pp.587-593
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• 2014

Let D be an integral domain with quotient field K, $\bar{D}$ denote the integral closure of D in K and * be a star-operation on D. In this paper, we study the *-Nagata ring of AP*MDs. More precisely, we show that D is an AP*MD and $D[X]{\subseteq}\bar{D}[X]$ is a root extension if and only if the *-Nagata ring $D[X]_{N_*}$ is an AB-domain, if and only if $D[X]_{N_*}$ is an AP-domain. We also prove that D is a P*MD if and only if D is an integrally closed AP*MD, if and only if D is a root closed AP*MD.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.117-120
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• 1988

A new current source inverter (CSl) with dc-side commutation and load-side energy recovery circuit is proposed with analysis and explanation of the circuit operation. Proposed inverter overcomes the most drawbacks of the conventional CSI's - high device voltage stress, low operating frequency range, large commutation capacitance, etc. - by employing simultaneous recovery and commutation concept. The new CSI employs only one commutation capacitor and it can be built with considerably low cost. The commutation energies are temporarily stored into a large dc capacitor and recovered to the load side, thus the device voltage stress is low and the efficiency is high in the proposed inverter. Computer simulation results are given at the steady state, and a guideline determining the commutation circuit is given.

• 대한전자공학회논문지
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• 제27권2호
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• pp.98-104
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• 1990

$P^+$형 다결정 실리콘 게이트와 n형 다결정 실리콘 게이트를 갖는 P채널 MOSFET를 제작하였다. 채널의 길이와 채널의 이온 주입 조건에 따라 SC-PMOSFET와 BC-PMOSFET의 transconductance 문턱저압저하 및 subthreshold 특성을 분석하였다. 측정된 소자의 특성으로 부터 SC-PMOSFET소자가 BC-PMOSFET 소자에 비하여 transconductance는 작으며 subthreshold 영역에서 누설전류도 작고 문턱 전압 저하및 DIBL영향이 작게 일어남을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제28권4호
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• pp.262-270
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• 2015

In this paper existing buildings, not a new buildings and house for living people not just a displaying and a viewing, created by the imagine effect or virtual simulation was applied various Active and Passive elements. After constructing zero-energy houses, through default case happened during operation period it is described problems and solutions about field part, work classification, installation by Location part, and Installation equipment part. Since then, to take advantage of this thesis, it's the purpose of this paper using as the baseline data for building a zero-energy house in another similar case.

• 호남수학학술지
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• 제33권3호
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• pp.419-424
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• 2011

Let D be an integral domain, Spec(D) the set of prime ideals of D, and X a subspace of the Zariski topology on Spec(D). We show that X is compact if and only if given any ideal I of D with $I{\nsubseteq}P$ for all $P{\in}X$, there exists a finitely generated idea $J{\subseteq}I$ such that $J{\nsubseteq}P$ for all $P{\in}X$. We also prove that if D = ${\cap}_{P{\in}X}D_P$ and if * is the star-operation on D induced by X, then X is compact if and only if * $_f$-Max(D) ${\subseteq}$X. As a corollary, we have that t-Max(D) is compact and that ${\mathcal{P}}$(D) = {P${\in}$ Spec(D)$|$P is minimal over (a : b) for some a, b${\in}$D} is compact if and only if t-Max(D) ${\subseteq}\;{\mathcal{P}}$(D).