• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.350-353
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• 2001

This study proposes a new method for the transmission system expansion planning using the fuzzy integer programming. It presents stepwise cost characteristics analysis which is a practical condition of an actual systems. A branch and bound method which includes the network flow method and the maximum flow-minimum cut set theorem has been used in order to proceed the stepwise cost characteristics analysis. Uncertainties of the permission of the construction cost and not strict reserve rate and load forecasting of expansion planning have been included and also processed using fuzzy set theory in this study. In order to proceed the latter analysis, the solving procedure is illustrated in detail by branch and bound method which includes the network flow method and maximum flow-minimum cut set theorem. Finally, case studies on 21-bus test system show that the algorithm proposed is efficiently applicable to the practical expansion planning of transmission systems in future.

• 대한공업교육학회지
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• 제31권2호
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• pp.350-363
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• 2006

최근 마이크로 엔드밀을 이용한 가공은 소형구조물이나 소형기계의 부품과 금형산업에서 양호한 표면 거칠기와 가공시간의 단축을 위해 고정도의 기술을 요구하고 있다. 마이크로 엔드밀을 이용한 가공에 있어서 가공조건은 절삭면의 표면거칠기에 커다란 영향을 미치게 된다. 따라서 본 연구에서는 마이크로 엔드밀을 이용하여 스테인리스 강(STS 304)의 표면을 가공하였고, 실험계획법에 의해 최적의 표면거칠기를 얻기 위한 가공조건에 대해 분산분석하였다. 본 연구를 통하여 마이크로 엔드밀에 의한 가공에서 가공조건은 절삭깊이, 스핀들의 회전수, 이송속도의 순서로 표면거칠기에 영향을 미치는 것을 알았다.

• 한국조경학회지
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• 제26권3호
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• pp.8-18
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• 1998

This study was to make a effective seed mixture types with Korean native plants by researching te seed timing of suitable woody plants and competitive germination results of various plants for the purpose of cut-slotes revegetation. The results are summarized as follows. 1. In field polystand experiment, comparative among severalcomposition combination for early coverage shows good condition. 2. In combination for early-coverage, mixture of native woody plants only seeded in May and June shows over 90% coverage. It was not inferior to the other mixture types. So mixture of Albizzia Julibrissin, Cymbopogon doeringii, Alnus hirsuta and Indigfera pseudo-tinctoria is able to use to mixture type. 3.In case of combination for scenic beauty, Rhus chinensis shows low germination in the mixture for scenic beauty. But 90 days after seeded in May, it recorded maximum 44 cm height, seeded in June recorede 18 cm height. 4. Lespedeza crytobotrya shows good elongation in the combination for early coverage and scenic beauty, but that effects on elongation of other plants. So, it demands close investigation about suitable mixing rate of plants. 5. Alnus hirsuta, Pinus thunbergii, Betula platyphylla, Spiraea prunifolia var. simpliciflora have been rarely germinated. So, the mixture of these plants wasn't adequate to use for revegatation.

• 화훼연구
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• 제17권3호
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• pp.185-189
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• 2009

2년생 안개초의 안정적인 월하(越夏)를 위해 1차 절화 수확 후 차광여부 및 잔존 지상부 절단 높이에 따른 고사주율, 개화 및 절화특성을 조사하였다. 차광처리에서 신초 발생소요일수가 짧고 발생 신초수도 많았고 고사주율은 낮은 경향이었으며, 특히 지상부를 높게 절단함으로서 고사주율이 낮아졌다. 개화는 무차광에서, 그리고 지상부를 높게 절단한 처리에서 빨라지는 경향이었고, 화경장, 측지수, 경경, 화수폭 및 절화량 등은 무차광, 9 cm 절단처리에서 가장 우수하였다. 비원추화서율과 로젯트 발생률도 무차광 9 cm 절단처리에서 낮았다.

• 원예과학기술지
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• 제17권6호
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• pp.762-764
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• 1999

전처리 후 저장방법, 저장온 습도, 저장기간 등 저장조건에 따른 절화품질과 수명을 비교함으로써 절화장미의 관상가치를 향상시키고자 본 실험을 수행하였다. 건식-저온처리의 경우 상자 내부의 온도가 저장고의 온도조건과 같은 $3^{\circ}C$를 유지하는데 12시간이 소요되었으며 습도는 20시간 경과 후 99%를 유지하였다. 꽃목굽음은 aluminum sulfate 혼합액 전처리에서 지연되었으며, 저장온도에서는 저온이, 저장방법에서는 습식이 적게 발생하는 것으로 나타났다. 흡수량은 저장시간이 길어질수록 상온($25^{\circ}C$)저장 보다는 저온($3^{\circ}C$)저장에서 높게 나타났다. 화경은 저장기간이 길어짐에 따라 처리별로 작아지는 경향을 보였으며 건식 저장보다 습식 저장에서 화경이 큰 것으로 나타났다. 절화수명은 aluminum sulfate 혼합액 전처리에서 저장기간에 관계없이 연장되었다. 습식저장은 건식보다 절화수명이 연장되었고 저장시간이 길어질수록 그 효과는 뚜렷하였으며, 저온저장($3^{\circ}C$)이 상온($25^{\circ}C$)에 비해 절화수명이 연장되었다.

• 한국정밀공학회지
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• 제20권11호
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• pp.47-54
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• 2003

Research during the past several years has established the effectiveness of acoustic emission (AE)-based sensing methodologies for machine condition analysis and process. AE has been proposed and evaluated for a variety of sensing tasks as well as for use as a technique for quantitative studies of manufacturing process. STD11 has been known as difficult-to-cut materials. The micro-grooving machine was developed for this study and the experiments were performed using CBN blade for machining STD11. Evaluating the machining conditions, frequency spectrum analysis of acoustic emission (AE) signals according to each conditions were applied. Fuzzy clustering method for associating the preprocessor outputs with the appropriate decisions was followed by frequency spectrum analysis. FFT is used to decompose AE signal into different frequency bands in time domain, the root mean square (RMS) values extracted from the decomposed signal of each frequency band were used as features.

• 한국표면공학회지
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• 제29권1호
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• pp.60-72
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• 1996

A photoetching process is widely used for small and high precision parts in machinery, electronic and semi-conductor industries. One of the high precision parts, grid is very important part of digitron which use electron display, and it is fabricated by only photoetching process because of high precision. In this study, to develop high precision digitron grid, characteristics of etching solution were investigated with electrochemical test, that was potentiodynamic test and immersion test in the ferric chloride solution and added some additives. Based on the electrochemical etching test, grid was fabricated by continuous photoetching process at various etching condition. From the result of measured line width and etching depth under-cut and etching factor were calculated. For the fabrication of 25$\mu\textrm{m}$ line width, optimal etching condition was etching temperature 40~$45^{\circ}C$, spray pressure 1.5kg/$\textrm{cm}^2$ and etching time 3~4min.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.466-471
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• 2003

The characteristics of a rock joint which influence the stability of rock mass structures, such as the cut slopes and the tunnels, are largely controlled by the conditions of the rock joint as well as its boundary conditions. Boundary conditions can be represented by assuming that the deformability(or stiffness) of the rock mass surrounding the joints is modelled by a spring with stiffness. A new direct shear apparatus is developed in this study, which adapts a servo control system using PID algorithm. This apparatus can be used to investigate the various aspects of shear characteristics of the rock joints at conditions of constant normal stress and constant normal stiffness and so on. It is possible that the behavior under the constant normal stiffness condition can be predicted by the normalized graphic method with results obtained from the tests in the constant normal stress condition.

• 한국기계가공학회지
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• 제11권5호
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• pp.29-34
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• 2012

This study describes the selection of optimum machining conditions for a high-hardness resin by using a large 5-axis machine. The experiments were conducted to examine the main factors that affect the surface roughness, such as the spindle speed, axial and radial depths of the cut, and pattern of the cutter path. To analyze the experiment results, the factor with the biggest impact on machining was determined using the smaller-the-better characteristic of the Taguchi method; the effectiveness of the experiment was then confirmed by verifying the selected optimum machining condition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1018-1021
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• 1997

This paper presents a result of simulation and improvement of grinding process for linear motion guide blocks. A simulation software, which is based on cylindrical grinding process. is used to predict the grinding wheel wear during the grinding process. To validate the simulation, the simulation result is compared with the experimental one. Simulation study is extended to obtain an optimal grinding condition for minimizing the grinding wheel wear. The optimal condition is validated through an experiment.