• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1262-1266
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• 1999

More precise operation and control is required to ensure the stability and security of modern large power systems that is a complicated and widely dispersed structure. To ensure the precise operation and control of modern power system, most of all, precise monitoring and measurement of the various state values of power system is required. This paper discusses phasor measurement unit using synchronization signals from the GPS satellite system- Synchronized Phasor Measurement Unit. Considering the power system operation state, the transmitting data format over modems is defined. To provide all available information, PMU process the measurements to generate three phase symmetrical component. This paper proposes the transmitted data format and implements the PMU model using EMTP/Models. The validity of proposed model is confirmed through several contingency on the simple power system.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.60-74
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• 2002

In this study, normal, log-normal, triangular, uniform. Weibull, Erlang and unit beta probability density functions are tried to represent the behaviour of frequency distributions of workpiece dimensions collected from various manufacturing firms. Among the distribution functions, the unit beta distribution function is found to be the best fit using the chi-square test of fit. An attempt is made for the adoption of the unit beta model to x-bar charts of quality control in manufacturing. In this direction, upper and lower control limits (UCL and LCL) of x-bar control charts of dimension measurements are estimated for the beta model, and the observed differences between the beta and normal model control limits are discussed for the measurement sets.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2004년도 추계학술대회 논문집
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• pp.75-80
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• 2004

This study was designed to examine characteristics of apartment floor plans that have been recently available. Content analysis was conducted, and 232 apartment floor plans were examined. This study indicated that the front width and the number of front bays also notably increased. Also, two bathrooms in a unit have been increasing, and three bedrooms were very popular. The conspicuous change of floor plan component is the appearance of entrance lobby. It was noted that dress room and powder room that appeared in a larger unit were adopted in small one. Housing suppliers have continuously attempted to have partial change in unit floor plan to accommodate consumers' diverse needs and lifestyle, Further analysis on our residential culture and continuous study on various development of floor plan types need to be made.

• 한국정밀공학회지
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• 제23권2호
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• pp.65-72
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• 2006

Downcoiler is one of the major facilities in hot strip mill operation. The key to good coiling is having good equipment, modem control systems, excellent maintenance and an understanding of coiling process. Therefore, this study aims to develop a program that is useful for calculating machine design parameters and simulating coiling process. In this study, the pinching and coiling mechanism of the downcoiler was thoroughly studied and some of operational factors and their effects on the coiling process were investigated. The software was developed to estimate engineering parameters for coiler component design and to determine optimal setting values for successful coiling operation. In order to check the accuracy and usefulness of the developed software, the simulation of the downcoiler in $\#2$ Hot Strip Mill in Pohang Works was performed. The simulation results suggested that the set-up value for unit tension could be lowered. Test coiling operation by using the lowered set-up value for unit tension resulted in much more successful coiling in the aspect of strip quality and power consumption.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.211-215
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• 2004

This paper describes the result of structure analysis and load test of torque arm for driving gear unit. The purpose of the analysis and test is to evaluate an safety which torque arm shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load. Driving gear unit consist of gearbox and torque arm. Both components, torque arm is significant component subjected to the vehicle and motor loads. The evaluation methode is used the FEM analysis, static and fatigue test. The test results have been very safety and stable for design load conditions.

• 전기학회논문지
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• 제57권12호
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• pp.2285-2290
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• 2008

Even though efficiency of coal-fired power plant is proportional to operating temperature, increasement of operating temperature is limited by a technological level of each power plant component. It is an alternative plan to increase operating pressure up to ultra super critical point for efficiency enhancement. It is difficult to control process of power plant in ultra super critical point because that point has highly nonlinear characteristics. In this paper, new control logic, Unit Response Optimizer Controller(URO Controller) which is based on Fuzzy logic and Model Predictive Controller, is introduced for better performance. Then its performance is tested and analyzed with design guideline.

• 한국생산제조학회지
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• 제21권1호
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• pp.156-160
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• 2012

Recently WCDMA signal transmission technology by large output microwave antenna have showed reduction of human resources and operating expense. But the existing antenna brackets cost is very expensive also its structure and functions are complicated. Unit brackets, suspending some sensors, subjected to acceleration loads, often fail due to self-vibration. To prevent such failures, it is necessary to understand the fatigue failure mode and to evaluate the fatigue life using tests or analysis techniques. The objective of this study is to develop the component test specifications, which are applicable to predict fatigue life at initial product design step, for unit brackets using vibration fatigue technique. So its application is limited to installation and management. In this project, we studied about more convenient bracket for microwave antennas through improvement on the existing antenna bracket's shortcoming and could develop an improved universal antenna bracket system for simple installation and application.

• Carbon letters
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• 제5권1호
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• pp.6-11
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• 2004

In spite of unparalleled combination of essential material properties for brake linings and clutch facings, replacement for asbestos is seriously called for since it is a health hazard. Once asbestos is replaced with other material then composition and properties of brake pad changes. In certain cases hardness of the material may be high enough to affect the rotor material. In this study, hardness of the brake pad has been controlled using suitable reinforcement materials like glass, carbon and Kevlar pulp. Brake pad formulations were made using CNSL (cashew net shell liquid) modified phenolic resin as a binder, graphite or cashew dust as a friction modifier and barium sulphate, talc and wollastonite as fillers. Influence of each component on the hardness value has been studied and a proper formulation has been arrived at to obtain hardness values around 35 on Scleroscopic scale. Friction and wear properties of the respective brake pad materials have been measured on a dynamometer and their performance was evaluated.

• 한국컴퓨터정보학회논문지
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• 제24권2호
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• pp.217-225
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• 2019

In this paper, we proposed comparison of software education units according to 2015 Revised National Curriculum. Comparative analysis of 6 Practical Arts textbooks was conducted especially on the software education units. The analysis criteria were decided to be unit system, unit structure, learning objectives, the way of placing contents, activities, supporting materials, providing resources, and evaluation. As a result, the software education units have secured a lot of quantity compared to the total number of units. And the affective domain of the learning objectives is shown to be lacking. All the textbooks were uniformly arranged the component of contents described in 2015 revised national curriculum. Cooperative activities are strengthened compared to the previouse curriculum. On the other hand, evaluations have a large variation among textbooks and some have fewer types.

• 한국도서관정보학회지
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• 제30권1호
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• pp.61-92
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• 1999

이 연구는 1990년 이전에 설립된 90개 4년제 대학을 대상으로 대학도서관의 11개 내외적 구성요소와 지원수 간의 중다상관관계를 분석하고, 이를 근거로 중다회귀분석기법과 사서직원 대 비사서직원의 구성비율을 이용하여 우리나라 실정을 고려한 사서직원 수와 전체직원 수의 산출공식 모형안을 제시한 것이다. 이 연구의 결과로 도출된 직원 수 산출공식 모형은 다음과 같다. (1) 사서직원 수 = 3.016+0.0l6x총 장서수(단위 : 천권) -0.008x연간증가책수(단위 : 백권)+0.031x대학원등록학생수(단위 : 십명)+0.069x마부등록하생수(단위 : 백명)+0.093x자료구입비(단위 : 천만원). (2) 전체직원 수 = 4.638+0.024x총장서수(단위 : 천권) -0.012x연간증가책수(단위 : 백권)+0.047x대학원등록학생수(단위 : 십명)+0.106x학부등록학생수(단위 : 백명)+0.066x자료구입비(단위 : 천만원).