• 설비공학논문집
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• 제7권1호
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• pp.42-51
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• 1995

In order to establish a theoretical basis for the analyses of transient behaviors in stratified thermal storage tanks, analytical approaches to an improved one-dimensional model are made. In the present model the storage tank is treated as a finite region with an adiabatic tank exit, whereas it has been considered as a simple semi-infinite region previously. Application of the Laplace transformation and the Inversion theorem to the governing equations makes it possible to obtain an exact infinite-series solution, which is convergent only at sufficiently large time. Accordingly a complementary solution which is available for short times, i.e., the time range of this study is sought by an approximate method. The approximate solution which is rigorously validated through the examination of neglected terms in the solution procedure agrees quite well with the exact one. Moreover, it is simpler to use and more convenient to interpret the physical meaning of the solution. Comparison of the present solution with the previous ones shows relatively large difference near the tank bottom, which results from the more realistic boundary condition adopted in the present model. Some representative results by the approximate solution including effects of the Peclet number on temperature distrbutions are illustrated to show the utility of this study. In consequence, it is expected that the present results based on the improved model replace the foregoing ones as a new theoretical reference for studies of thermal stratification fields.

• 산업경영시스템학회지
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• 제25권5호
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• pp.9-14
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• 2002

A capital investment problem is essentially one of determining whether the anticipated cash inflows from a proposed project are sufficiently attractive to invest funds in the project. The net present value(NPV) criterion and internal rate of return(IRR) criterion are widely used as means of making investment decisions. A positive NPV means the equivalent worth of the inflows is greater than the equivalent worth of outflows, so, the project makes profit. Business people are familiar with rates of return because they all borrow money to finance ventures, even if the money they borrow is their own. Thus they are apt to use the IRR in preference to the NPV. The IRR can be defined as the discount rate that causes the net present value of a cash flow to equal zero. Why the project are accepted if the project's IRR is greater than the investor's minimum attractive rate of return\ulcorner Against the NPV, the definition cannot distinctly explain the concept of the IRR as decision criterion. We present a new definition of the IRR as the ratio of profit on the invested capital.

• Ocean Systems Engineering
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• 제5권4호
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• pp.279-299
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• 2015

Suction anchors are widely adopted and play an important role in mooring systems. However, how to reliably predict the failure mode and ultimate pullout capacity of the anchor in sand, especially by an easy-to-use theoretical method, is still a great challenge. Existing methods for predicting the inclined pullout capacity of suction anchors in sand are mainly based on experiments or finite element analysis. In the present work, based on a rational mechanical model for suction anchors and the failure mechanism of the anchor in the seabed, an analytical model is developed which can predict the failure mode and ultimate pullout capacity of suction anchors in sand under inclined loading. Detailed parametric analysis is performed to explore the effects of different parameters on the failure mode and ultimate pullout capacity of the anchor. To examine the present model, the results from experiments and finite element analysis are employed to compare with the theoretical predictions, and a general agreement is obtained. An analytical method that can evaluate the optimal position of the attachment point is also proposed in the present study. The present work demonstrates that the failure mode and pullout capacity of suction anchors in sand can be easily and reasonably predicted by the theoretical model, which might be a useful supplement to the experimental and numerical methods in analyzing the behavior of suction anchors.

• 한국실내디자인학회논문집
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• 제25권1호
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• pp.13-23
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• 2016

2014 Venice Biennale of Architecture, presented by general director Rem Koolhaas, has shown the distinct difference between his present displays and past displays. Under the theme of FUNDAMENTALS and ABSORBING MODERNITY, Rem Koolhaas has developed his own unique way which is a research-oriented display technique to explain the difference at the exhibition. The purpose of this study is to define a research-oriented display technique as realism rhetoric for the opened dialectic and identify its aspect of a methodic approach. This report investigated not only Rem Koolhaas's thought and theoretical approach through his work but also the comparison of between his present and past displays. His display is based on the constellation of Central Pavilion, National Pavilions, and Arsenale display and reflected the reality of architecture in self-deception through the metonymical interaction of various facts and records. Rem Koolhaas called it the composition of contradiction. In his work, the spatial situation which is the present has been made with the intervention of historical events and has revived the reality of architecture. Also, the present is a montage of the strict control of architecture, the isolation from the architecture itself, and the autonomic communication with other fields. Finally, as a result of his work, Rem Koolhaas has shown that his display is not the end of phase but a phase of creation.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2011년도 춘계학술발표대회 논문집
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• pp.93-96
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• 2011

'Hanok(韓屋)' is the settlement that our ancestors completed for our lives through multiple verifications. Thus, there exists our nation's identity and a variety of tangible and intangible cultural elements are included in that settlement. Even though the dwelling planning of Hanok has been introduced by the modern trends of traditional style, it can not present the type of various space compositions according to the area and living characteristics and it shows a disparity in our real life through the introduction of the traditional Hanok's elements which are not fit into contemporary housing without filtration. To solve these problems, it must need to study on cases based on the present situation of the Hanok and analysis on characteristics. For the Hanok to meet the development of modern residence, there needs to study on many fields such as plan, complex, structure, material. Among them, this study intends to present the preliminary data for the improvement of Hanok's effectiveness by understanding and analyzing the current situation focusing on the natural transformation of Hanok which are currently building in Milyang Area. Also, as the second step of this study, this study attempts to analyze based on the present situation of New Hanok in Kyeongnam province by expanding the range.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2001년도 추계학술대회
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• pp.37-57
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• 2001

Digital technology enhanced the improvement of technological aspects in the both broadcasting and telecommunications industries. The infrastructures of each industry converged to one, which impacts not only on technology but also on the broadcasting service. The current broadcasting service is characterized by one-way service, but it'll changed to be customized, or two-way service that reflects the interest of customers. This change requires a new standard to categorize and analyze the future broadcasting service converged and market structure, differing from the present standard based on the transmission channels. This study aims at forecasting the demand of interactive TV service as a representative broadcasting service in the near future, and analyzing the market structure of the broadcasting services. We assume that the present broadcasting and information and telecommunications services such as terrestrial, cable TV, satellite, digital TV services and high-speed broadband service have strong relationship with interactive TV service. First we use Bass diffusion method to predict the diffusion curve of the present five services. Then we analyze the relationship between the present services and interactive TV service by Delphi method. Finally we estimate the potential subscription number of interactive TV service based on the relationship among the services and diffusion parameters.

• 대한전기학회논문지:전력기술부문A
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• 제51권6호
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• pp.290-295
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• 2002

The present assignment in installing the number of switches for distribution line was made on the basis of a normal feeder capacity 7,000kVA in KEPCO(Korea Electric Power Corporation), Korea. But the normal capacity is revised to 10000kVA in 1998. Even increasing limit of the operating capacity of the distribution lines enables us to give some benefit for the operation flexibility and investment cost of the distribution system. It is disadvantageous in the viewpoint of supply reliability. In distribution systems, switches are equipped to improve the reliability of distribution systems by minimizing the outage section due to fault and maintenance. Utility generally improves the reliability by minimizing the length of outage section, which is caused by fault and maintenance, through switch equipment on distribution system. In order to cope with the changes such as operation capacity, it is necessary to study whether the present criteria is reasonable or not, also to confirm whether the present criteria of installing switches in line is improved or not. In this study, we proposes the number of switch per feeder on the basis of present operation capacity in distribution system.

• 대한가정학회지
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• 제30권3호
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• pp.141-158
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• 1992

The purpose of this study was to identify general characteristics of social lifespaces in Korean family houses and to investigate the changes in the physical aspects and room functions of social lifespaces from Yi-dynasty to the present. The documentary research method was used for this study. Total of 972 out of 1,109 floor plans were analyzed for this study. The major findings were that changes of social lifespaces from Yi-dynasty to the present have been affected by natural and socio-cultural environments. The changes in the physical aspects of social lifespaces have shown from one or two social lifespaces to various single-purpose social lifespaces such as living room, family room, drawing room, and study room. In the past, the cnetral social lifespaces, Anbang(women's quarter) was larger than the living room/Daechung(wooden floor) but the living room in the present has become a central social lifespaces and larger. The room function of Anbang has changed from multi-purpose space to private space. Living room/Daechung had used as a pathway rather than a social lifespaces in the past but the living room has played many fuctional roles of family social activities in the present. The kitchen has also begun to use as a social lifespace. This is a new symptom that kitchen and dining spaces will be included as a new social lifespaces.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.257-266
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• 1999

This paper presents a method of seismic analysis for a cylindrical liquid storage structure on/in horizontally layered half.space considering the effects of the interior fluid and exterior soil medium in the frequency domain. To capture the essence of fluid-structure-soil interaction effects effectively, a mixed finite element with two-field (u, p) approximation is employed to model the compressive inviscid fluid, while the structure and soil medium are presented by the 3-D axisymmetric finite elements and dynamic infinite elements. The present FE-based method can be applied to the system with complex geometry of fluid region as well as with inhomogeneous near-field soil medium, since it can directly model both the fluid and the soil. For the purpose of verification, dominant peak frequencies in transfer functions for horizontal motions of cylindrical fluid storage tanks with rigid massless foundation on a homogeneous viscoelastic half.space are compared with those by two different added mass approaches for the fluid motion. The comparison indicates that the Present FE-based methodology gives accurate solution for the fluid-structure-soil interaction problem. Finally, as a demonstration of versatility of the present study, a seismic analysis for a real-scale LNG storage tank embedded in layered half.space is carried out, and its member forces along the height of the structure are compared with those by an added mass approach developed by the present writers.

• 대한공업교육학회지
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• 제42권1호
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• pp.53-67
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• 2017

본 연구는 중등단계 직업교육 기관에 대한 중학교 교장의 과거와 현재, 미래의 인식의 변화를 분석하여 중등단계 직업교육 기관의 인식 변화를 구명하고, 중등단계 직업교육 기관의 인식 개선을 위한 정책 지원에 대한 기초 자료를 제시하기 위해 수행되었다. 이를 위해 중학교 교장 214명을 대상으로 하여 중등단계 직업교육 기관에 대한 과거와 현재, 미래의 인식을 조사하여 분석하였다. 연구 결과 첫째, 중학교 교장이 인식한 중등단계 직업교육 기관에 대한 인식은 과거보다 현재가 더 긍정적으로 변화하였고, 현재보다 미래가 더 긍정적으로 변화할 것으로 나타났다. 이는 2005년 이후 다양한 중등단계 직업교육 정책이 직업교육의 인식 개선의 측면에서 긍정적 효과가 있음으로 해석할 수 있다. 둘째, 중학교 교장의 중등단계 직업교육 기관에 대한 과거 현재 미래의 인식의 내용에 대한 순위 변화를 분석한 결과, "적성과 소질을 일찍 살릴 수 있음"과 "졸업 후 학생의 경제적 자립이 빠름"과 관련된 내용에서 과거 현재 미래 모두 긍정적으로 인식하고 있었다. "동일계 대학 진학이 용이함"과 관련된 내용은 과거와 현재에서는 높은 순위로 인식하였으나, 미래에는 낮은 순위로 인식될 것으로 예상하고 있어 정부의 정책의 방향에 따른 중등단계 직업교육 기관에 대한 인식도 달라지고 있음을 확인하였다.