• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1920-1925
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• 2007

A transformer is a device that changes the current and voltage by electricity induced between coil and core steel, and it is composed of metals and insulating materials. In the core of the transformer, the thermal load is generated by electric loss and the high temperature can make the break of insulating. So we must cool down the temperature of transformer by external radiators. According to cooling fan's usage, there are two cooling types, OA(Oil Natural Air Natural) and FA(Oil Natural Air Forced). For this study, we used Fluent 6.2 and analyzed the cooling characteristic of radiator. we calculated 1-fin of detail modeling that is similar to honeycomb structure and multi-fin(18-fin) calculation for OA and FA types. For the sensitivity study, we have different positions(side, under) of cooling fans for forced convection of FA type. The calculation results were compared with the measurement data which obtained from 135.45/69kV ultra transformer flowrate and temperature test. The aim of the study is to assess the Fluent code prediction on the radiator calculation and to use the data for optimizing transformer radiator design.

• 한국시뮬레이션학회논문지
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• 제16권4호
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• pp.1-12
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• 2007

본 논문에서는 미래의 수중 교전 시뮬레이션에서 공통적으로 사용될 수 있도록 재사용성 및 상호운용성과 공학 시뮬레이션 등 앞으로의 확장성을 고려하여 수중 교전에 사용되는 잠수함 체계에 대한 표준모델을 어떠한 개념에서 어떠한 형태로 정립할 것인가에 대해 기술하였다. 본 연구를 통해 교전 수준 잠수함 체계 표준모델에 대한 모델아키텍쳐를 정립하고 개별 구성요소에 대한 모델링 방안을 개발하였으며 모델의 입출력 자료 및 정보 흐름도를 도출하였다. 본 연구에서는 비음향 탐지 모델 및 비음향 스텔스 모델 등 수중 교전에 해당하지 않는 분야는 제외하였으므로 향후 이에 대한 추가 연구가 필요하다.

• 한국재료학회지
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• 제13권11호
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• pp.711-716
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• 2003

Gate length, height, and silicide thickness have all been shrinking linearly as device density has progressively increased over the years. We investigated the effect of the cobalt diffusion during the silicide formation process on the 60$\AA$-thick gate oxide lying underneath the Ti/Co and Co/Ti bilayers. We prepared four different cobalt silicides, which have similar sheet resistance, made from the film structure of Co/Ti(interlayer), and Ti(capping layer)/Co, and peformed the current-voltage, time-to-break down, and capacitance-voltage measurements. Our result revealed that the cobalt silicide process without the Ti capping layer allowed cobalt atoms to diffuse into the upper interface of gate oxides. We propose that 100$\AA$-thick titanium interlayer may lessen the diffusion of cobalt to gate oxides in 1500-$\AA$ height polysilicon gates.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2002년도 학술대회지
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• pp.367-370
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• 2002

건설 프로젝트의 초기단계에 타당성을 검토함에 있어서 공통가설공사의 경우 설계도서상에 표시가 되지 않거나, 시방서상에 간략하게 서술되어 있기 때문에 담당자의 경험 의존율이 다른 공종에 비해 높다. 이런 초기단계의 결전은 프로젝트의 진행과 더불어 많은 문제점들을 야기 시킬 가능성이 있다. 따라서 최근 활발히 논의가 되고 있는 기존 공사정보에 대한 실적 데이터베이스와 공통가설공사의 분류체계를 포함한 시스템을 개발하여 자료들을 분석, 활용함으로써 시공전(Pre-Construction) 단계의 공통가설공사에 대한 작업 및 원가 예측을 용이하게 하고, 후에 Feed Back 됨으로써 정확한 건설 프로젝트 타당성 분석을 가능케 하고자 한다.

• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.767-770
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• 2010

In this work, we investigated the static characteristics of 4H-SiC vertical metal-oxidesemiconductor field effect transistors (VMOSFETs) by adjusting the doping level of n-epilayer and the effect of a current spreading layer (CSL), which was inserted below the p-base region with highly doped n+ state ($5{\times}10^{17}cm^{-3}$). The structure of SiC VMOSFET was designed by using a 2-dimensional device simulator (ATLAS, Silvaco Inc.). By varying the n-epilayer doping concentration from $1{\times}10^{16}cm^{-3}$ to $1{\times}10^{17}cm^{-3}$, we investigated the static characteristics of SiC VMOSFETs such as blocking voltages and on-resistances. We found that CSL helps distribute the electron flow more uniformly, minimizing current crowding at the top of the drift region and reducing the drift layer resistance. For that reason, silicon carbide VMOSFET structures of highly intensified blocking voltages with good figures of merit can be achieved by adjusting CSL and doping level of n-epilayer.

• 건축역사연구
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• 제22권3호
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• pp.27-36
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• 2013

The purpose of this study is to analyze the process of lots-subdivision within the block of Gaeksa at Dongnae-bu under the rule of Japanese Imperialism. Gaeksa of the old government office was the sanctuary that symbolized the sovereignty. Therefore it was naturally a main object of demolition and then the site was converted to other purpose. And Gaeksa was not only converted into the elementary school and the public market but the historic site also processed to break down for opening the road through Japanese Occupation of Korea. The main reasons of lots-subdivision were the transfer from state property to private ownership and the urban development project. Needless to say, the particular major reason was derived from the intention of Japanese Imperialism to destroy the traditional urban. As a result, Gaeksa can not be recognized the traces of today and contributes to the demolition of the remaining ancient building. Finally the deformed urban structure was left over from destroyed building.

• The Korean Journal of Ceramics
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• 제6권1호
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• pp.74-77
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• 2000

Ta-doped PZT thin films prepared by reactive co-sputtering method could be transformed into single grained perovskite structure utilizing physical etching of Pt bottom electrode. It is found that PZT perovskite phase on damaged (111) Pt electrode by IMD was more easily crystallized than random oriented Pt electrode and less crystallized than (111) Pt electrode. This shows that amorphized Pt electrode surface by IMD process has an effect on crystallization of PZT perovskite phase. 40$\mu\textrm{m}\times40\mu\textrm{m}$ square shape single grain PZT array could be obtained utilizing the difference of incubation time for nucleation of rosettes between ion damaged Pt and (111) oriented Pt electrode. Single grained PZT thin films show low leakage current density of $1\times10^{-7}$ A/$\textrm{cm}^2$ and high break down field of 440kV/cm. The loss of remanent polarization after $10^{11}$ cycles was less than 15% of initial value.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1890-1901
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• 2022

We have assessed the applicability of the thermal-hydraulic system analysis code, SPACE, to a small modular reactor called SMART. For the assessment, the experimental data from a scale-down integral-test facility, SMART-ITL, were used. It was conformed that the SPACE code unrealistically calculates the safety injection flow rate through the CMT and SIT during a small-break loss-of-coolant experiment. This unrealistic behavior was due to the overprediction of interfacial heat transfer at the steam-water interface in a vertically stratified flow in the tanks. In this study, a special thermal-hydraulic component model has been developed to realistically calculate the interfacial heat transfer when a strong non-equilibrium two-phase flow is formed in the CMT or SIT. Additionally, we developed a special heat structure model, which analytically calculates the heat transfer from the hot steam to the cold tank wall. The combination of two models for the tank are called the special component model. We assessed it using the SMART-ITL passive safety injection system (PSIS) test data. The results showed that the special component model well predicts the transient behaviors of the CMT and SIT.

• The Journal of Asian Finance, Economics and Business
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• 제9권2호
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• pp.133-140
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• 2022

The impact of State management factors on transfer pricing activities of foreign direct investment enterprises in Vietnam is examined in this study. This adds to the empirical evidence on factors affecting transfer pricing activities of foreign-invested enterprises in Vietnam. A questionnaire survey of officials directly involved in the inspection of transfer pricing activities is used as the research method. The study yielded 226 questionnaires. The author chose 210 questionnaires after deleting those that were ineligible due to a large number of blank cells. The following procedures are used to process the data from the satisfied votes: Cronbach's Alpha test to measure the reliability of the scale; Exploratory factor analysis to break down data into smaller sets of variables to discover the underlying structure; Descriptive analysis to describe the underlying quantitative features of the data; Correlation and regression analysis to evaluate the relationship between variables with the support of SPSS 25 software. Inspection pressure, professional inspector qualifications, and inspector role, State control organization, inspector professionalism, legal corridor on transfer pricing control, macroeconomic situation, and investment environment have a positive impact on state management on transfer price operations, according to research findings. The author has provided solutions to increase the efficiency of State management on transfer pricing operations of foreign-invested businesses in Vietnam based on the research findings.

• 대한안전경영과학회지
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• 제15권3호
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• pp.151-161
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• 2013

This paper proposes a strategic model of linkage between productivity metrics and financial accounting metrics to properly evaluate the financial effect of TPM activities and the business performance. This linkage strategy provides a connection tool for clear communication between factory-level and headquarters that the metrics proposed by this paper ultimately improves a quality of support from the management by receiving the factors required for productivity activities in the practical field. This factor includes such as equipment, raw materials and labors. Here, we propose that chain reaction models using break down structure of productivity metrics and financial metrics enhance the knowledge sharing of KPI (Key Performance Indicator) which generally tend to create oversimplified communication between management in headquarters and employees in the practical fields. The productivity metrics include OEE(Overall Equipment Effectiveness) of TPM (Total Productive Maintenance), OLE (Overall Labor Effectiveness) of PAC(Performance and Analysis and Control) activities, and OYE (Overall Yield Effectiveness) of TMM(Total Material Management) activities. The financial accounting metrics include ROE(Return on Equity), ROA(Return on Asset), and AVR(Added-Value Rate). The suggested chain reaction model selects the financial metrics as initial stage and branch down until final stage of productivity metrics. When demand exceeds supply, an ideal speed rate, the lean OEE strategy can be initially applied to reduce the gap between the demand and supply, then apply variable costing to estimate correct amount of operating profit. In addition, the paper presents a new type of model for linkage between financial accounting metrics including CAPEX(Capital Expenditure), OPEX(Operating Expenditure), EVA(Economic Added Value), DCL(Degree of Combined Leverage), and TPM productivity activities including AM(Autonomous Maintenance), PM(Preventive Maintenance), MP(Maintenance Prevention) and QM(Quality Maintenance). In order to support the evidence of proposed linkage strategy, a case analysis on 52 projects from national TPM contest from 2011 to 2012 is analyzed. The case presents the classification of CAPEX and OPEX activities from TPM, and proposes the correct implementation of financial effect for TPM projects.