• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.542-545
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• 2007

A semi-closed loop ground heat exchanger is proposed and its performance is compared through the measuring the effective thermal conductivity of the ground. In-situ tests based on the line source model are carried out to evaluate the thermal characteristics of each ground heat exchanger which has different penetration water flow rate. The test results show the increasing effective thermal conductivity of ground as the penetration water flow rate(PWFR) is increased. Therefore, the higher thermal performance of the proposed semi-closed ground heat exchanger can be expected.

• 자동차안전학회지
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• 제13권4호
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• pp.73-80
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• 2021

Recently, Korea has established a plan for the supply of hydrogen vehicles and is promoting the expansion of the supply. Risk factors for hydrogen vehicles are hydrogen leakage, jet fire, and explosion. Therefore Safety measures are necessary for this hazard. In addition, risks in semi-closed spaces such as tunnels, underground roads, and underground parking lots should be analyzed. In this study, an explosion experiment was conducted on a hydrogen tank used in a hydrogen vehicle to analyze the risk of a hydrogen vehicle explosion accident that may occur in a semi-closed space. As results, the effect on the structure and the human body was analyzed using the overpressure and impulse values for each distance generated during the explosion.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제29권1호
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• pp.93-102
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• 2022

The impact of programming languages in the research sector has helped lot of researchers to broaden their view and extend their work without any limitation. More importantly, even the complex problems can be solved in no matter of time while converting them into a programming language. This convenience provides upper hand for the researchers as it places them in a comfort zone where they can work without much stress. With this context, we have converted the research problems in Topology into programming language with the help of Python. In this paper, we have developed a Python program to find the weaker form of closed sets namely alpha closed set, semi closed set, pre closed set, beta closed set and regular closed set.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제11권3호
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• pp.37-41
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• 2007

The semi-convexity for planar shapes has been recently introduced in [2]. As a generalization of the convextiy, semi-convexity is closed under the Minkowski sum. But the definition of semi-convexity requires that the shape boundary should satifisfy a differentiability condition $C^{1:1}$, which means that it should be possible to take the normal vector field along the domain's extended boundary. In view of the fact that the semi-convextiy is a most natural generalization of the convexity in many respects, this is a severe restriction for the semi-convexity, since the convexity requires no such a priori differentiability condition. In this paper, we generalize the semi-convexity to the closure of the class of semi-convex $\mathcal{M}$-domains for any Minkowski class $\mathcal{M}$, and show that this generalized semi-convexity is also closed under Minkowski sum.

• Kyungpook Mathematical Journal
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• 제54권2호
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• pp.173-188
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• 2014

In this paper, a new class of open sets, namely ${\gamma}^*$-pre-open sets was introduced and its basic properties were studied. Moreover a new type of topology ${\tau}_{{\gamma}p^*}$ was generated using ${\gamma}^*$-pre-open sets and characterized the resultant topological space (X, ${\tau}_{{\gamma}p^*}$) as ${\gamma}^*$-pre-$T_{\frac{1}{2}}$ space.

• 대한수학회논문집
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• 제9권3호
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• pp.593-598
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• 1994

In this note we give some results on the jump (due to Kato [5] and West [7]) of a semi-Fredholm operator. Throughout this note, suppose X is an Banach space and write L(X) for the set of all bounded linear operators on X. A operator $T \in L(x)$ is called upper semi-Fredholm if it has closed range with finite dimensional null space, and lower semi-Fredholm if it has closed range with its range of finite co-dimension. It T is either upper or lower semi-Fredholm we shall call it semi-Fredholm and Fredholm it is both. The index of a (semi-) Fredholm operator T is given by $$ index(T) = n(T) = d(T),$$ where $n(T) = dim T^{-1}(0)$ and d(T) = codim T(X).

• Korean Journal of Mathematics
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• 제16권3호
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• pp.291-300
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• 2008

In this paper, we introduce several types of r-semi-generalized fuzzy compactness and fuzzy r-compactness in fuzzy topological spaces and investigate the relations between these compactness.

• 대한수학회논문집
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• 제30권4호
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• pp.493-504
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• 2015

The aim of this paper is to present some properties of sT-continuous functions. Moreover, we obtain a characterization and preserving theorems of semi-compact, S-closed and s-closed spaces.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.446-453
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• 2000

The closed cycle diesel system is operated in closed circuit system where there is non air breathing with working fluid consisted of the combination of oxygen, argon and recycled exhaust gas for obtaining underwater or underground power sources. this study has been carried out to analysis the performance of closed cycle system by means of investigation on the combustion characteristics of diesel engine MTU8V183TE52 operating in open, semi-closed, and closed cycle modes. The combustion in closed mode starts a little bit earlier than in open cycle mode. The oxygen concentration and fuel consumption at 240kW closed cycle running are 21∼24% by volume and 77∼79kg/h, respectively. The maximum cylinder pressure and ignition delay time are investigated 110bar and 8.9degree. Also, The combustion simulation program has been studied to predict whether or not combustion. The results from numerical prediction for the basic, cylinder averaged quantities such as the cylinder pressure and the heat release showed excellent with the experimental data.

• 한국정밀공학회지
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• 제14권8호
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• pp.82-91
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• 1997

The major objective of this study is to establish analytical technique in order to analyze the behaviour of semi-solid material considering induction heating of the billet. Induction heating process is analyzed by using commerical finite element software. ANSYS. The finite element program, SFAC2D, for the simulation of deformation in semi-solid state is developed in the present study. The semi-solid behaviour is described by a viscoplastic model for the solid phase, and by the Darcy's law for the liquid flow. Simple compression and closed-die compression process considering induction heating are analyzed, and also it is found that the distribution of initial solid fraction of the billet has an important effect on deformation behaviour of semi-solid material. In order to verify the effectiveness of proposed analytical technique the simulation result is compared with experimental result.