• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.692-697
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• 1997

This paper presents a method of grinding and polishing automation of precision die after CNC machining. The method employs a robot system equipped with a pneumatic spindle and a special abrasive film pad. The robote program is automatically generated off-line from a PC and downloaded to robot controller. Position and orientation data for the program is supplied from cutter contact (CC) data of NC machining process. This eliminates separate robot teaching process. This paper aims at practical automation of die finishing process which is very time consuming and suffering from shortage of workpeople. Time loss for changeover from one product to next is eliminated by off-line programming exploiting appropriate NC machining data. Dextrous 6-axis robot with rigid wrist and simple tooling enables the process applicable to larger, rather complex 3 dimensional free surfaces

• 한국자동차공학회논문집
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• 제12권6호
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• pp.127-134
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• 2004

Three-dimensional numerical investigations are carried out to understand the combustion characteristics inside a DLN(dry low NOx) utility gas turbine combustor during the combustion mode change period by applying transient fuel flow rates in fuel supply system as numerical boundary conditions. The numerical solution domain comprises the complex combustor liner including cooling air holes, three types of fuel nozzles, a swirl vane, and a venturi. Detailed three-dimensional flow and temperature fields before and after combustion mode changeover have been analyzed. The results may be useful for further studies on the unfavorable phenomena, such as flashback or thermal damage of combustor parts when the combustion mode changes.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.411-412
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• 2017

본 논문에서는 전기자동차의 1회 충전 주행거리 연장 및 연비 향상을 위하여 주요 운전 영역에서의 평균효율 극대화를 할 수 있는 다단 변속 회로를 제안하였다. 제안한 회로는 Thyristor를 이용한 직 병렬 변속회로로 구성되어 있다. Thyristor의 특성으로 인해 과도상태 없고 끊김없는 변속이 가능하여 추가적인 스너버회로가 필요 없으며, 낮은 스위치손실로 인해 AC전동기 시스템의 고효율 및 경량화를 기대할 수 있다. 제안한 다단변속 시스템의 타당성을 검증하기 위하여 1kW 급 시작품 1대를 AC전동기와 연계하여 변속 동작을 검증하였다.

• 한국철도학회논문집
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• 제11권1호
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• pp.33-38
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• 2008

이종궤간(협궤/표준궤/광궤)이 존재하는 유라시아 철도네트워크(TCR 및 TSR 등)의 운송시간 및 비용을 절감하기 위하여, 이 구간을 자유롭게 운행할 수 있는 궤간 가변 장치의 개발이 중요하다. 따라서 궤간가변차량의 안전성을 확보하기 위하여 각 시스템 및 부품들의 구조해석을 통한 건전성을 평가하는 것이 필요하다. 본 연구에서는 개발중인 궤간가변 윤축시스템의 안정성 검토의 연구의 일환으로서, 궤간 변환구간 및 곡선부 주행시 차륜의 횡압하에 잠금부품들 사이의 접촉응력을 유한요소해석 시뮬레이터를 이용하여 평가하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.373-376
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• 2001

In this paper to cope with the reduction of products life-cycle as the variety of products along with the various demands of consumers, a virtual simulator is developed to make the changeover of manufacturing line efficient to embody a virtual simulation similar to a real manufacturing line. The developed virtual simulator can design a layout of a factory and make the time scheduling. Every factory has one simulator so that one product can be manufactured in the factories to use them as virtual factories. We suggest a scheme that heightens the ability to the diversity of manufacturing models by making the information of manufacturing lines and products models to be shared. The developed system embodies a virtual manufacturing line on the simulation using various manipulators and work cells as manufacturing components. we develop a virtual simulator system on Window 98/NT environment of Microsoft, operating system using of the greater part of PC user. Window program have a merit making GUI environment that programmer can use without the expert knowledge about hardware. A suer with the simulator can utilize an interface that makes one to manage the separate task process for each manufacturing module, change operator components and work cells, and easily teach tasks of each task module.

• 한국정밀공학회지
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• 제33권3호
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• pp.235-242
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• 2016

The purpose of this study is an attempt to improve the functionality of a conventional Fused Deposition Modeling (FDM) process using the Automatic Tool Changer (ATC) to perform multimaterial production and post-processing. Hybrid-FDM means a fusion of an Additive Manufacturing process and grinding process using the ATC system. In order to enhance the potentiality of production capacity for multi-material fabrication and surface roughness improvement, two extrusion tools and one grinding tool system are suggested. A pneumatic chuck is attached on a moving platform in the XY axes plane and an extrusion head and grinding head are placed in a docking station, allowing for a quick changeover with each other. Therefore, the manufacturing lead time can be reduced efficiently for the fabrication of a product.

• 한국산학기술학회논문지
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• 제13권5호
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• pp.1954-1962
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• 2012

최근 유럽과 아시아 사이의 물류 증가는 철도수송에 있어서 사회적/경제적으로 좋은 기회이며, 동시에 커다란 도전이 될 수 있다. 유라시아 대륙에는 다양한 궤간이 존재하고 있다. 이러한 궤간의 차이는 철도에 의한 화물수송시 장애요인중의 하나이다. 궤간 차이를 극복하기 위한 방법은 수송 화물의 유형에 따라 달라질 수 있으며, 국경 지점에 보관 창고 및 환적 설비와 같은 넓은 기반 시설과 많은 운영 인력수요와 같은 철도 수송 시스템의 운영에 많은 영향을 준다. 따라서 철도 수송 시스템의 효율성은 복잡한 하역 및 교환 기술에 관련된 궤간 극복 방법에 매우 의존한다. 본 논문은 궤간 극복 방법에 대한 기술적 평가를 기반으로 수송 시나리오의 효율성을 검토하고, 각 시나리오의 운영에서 요구되는 기술적 요소들을 기술하였다.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.423-431
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• 2022

The UPS(Uninterruptible Power Supply) system operates in the battery charging mode when the grid is normal, and in the UPS mode, which is the battery discharge mode when a grid error occurs. Since the UPS must supply the same voltage as the grid to the load within 4 [ms] in case of a grid error, the switching time and power recovery time should be short when controlling the output voltage and current of the UPS, and the power failure detection time is also important. The power outage detection algorithm using DFT(Discrete Fourier Transform) proposed in this paper compares the grid voltage waveform with the voltage waveform including the 9th harmonic generated through DFT using Schmitt trigger to detect power outage faster than the existing power outage monitoring algorithm. There are advantages. Therefore, it is possible to supply instant and stable power when switching modes in the UPS system. The multi-power-applied UPS system proposed in this paper uses DFT, which is faster than the conventional blackout monitoring algorithm in detecting power failure, to provide stable power to the load in a shorter time than the existing power outage monitoring algorithm when a system error occurs. The detection method was applied. The changeover time of mode switching was set to less than 4 [ms], which is 1/4 of the system cycle, in accordance with KSC 4310 regulation, which was established by the Industrial Standards Council on the regulation of uninterruptible power supply. A 10 [kW] UPS system in which commercial voltage, vehicle generator, and auxiliary diesel generator can be connected to each of the proposed transfer devices was constructed and the feasibility was verified by conducting an experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.450-451
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• 2018

본 논문에서는 전기자동차의 1회 충전 주행거리 연장 및 연비 향상을 위하여 주요 운전 영역에서의 평균효율을 극대화 시킬 수 있는 다단 변속 회로를 제안하였다. 제안한 회로는 Thyristor를 이용한 직 병렬 변속회로로 구성되어 있다. Thyristor의 특성으로 인해 과도상태가 없고 끊김없는 변속이 가능하여 추가적인 스너버 회로가 필요 없으며, 낮은 스위치 손실로 인해 전기자동차 구동 시스템의 고효율 및 저가격을 기대할 수 있다. 제안한 다단 변속 시스템의 타당성을 검증하기 위하여 80kW급 변속회로 AC 전동기와 연계하여 변속 동작을 검증하였다.

• Bulletin of the Korean Chemical Society
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• 제19권3호
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• pp.349-353
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• 1998

Solvolysis rates of substituted 2-aryl-1,1-dimethylethyl bromides (1) were determined in a variety of solvents such as aqueous mixtures of ethanol, acetone, 2,2,2-trifluoroethanol, and also mixtures of ethanol and TFE at 25 ℃, 35 ℃, and 45 ℃. The solvent effects were analyzed in terms of Winstein-Grunwald equation. The solvent effects of 1-4-MeO failed to give a single linear correlation against either Y or YCl (YBr), but exhibited a wide split pattern which could not be related to the solvent nucleophilicity. On the other hand 1-4-CH3 and 1-H gave a fairly good linearity. In the case of 1-4-MeO, a fairly good linearity was observed against YΔ defined from the solvolysis of 4-methoxyneophyl tosylate. It is assumed that resonance interaction between reaction site and aryl-π-system operates to give charge delocalization regardless of the different solvolysis mechanisms. The Hammett-Brown treatment of the solvolytic rate constant of compounds 1 was obtained non-linear two separated lines of - 1.06 to - 1.46, suggesting of mechanistic changeover from kc-ks to kΔ on going from electron-withdrawing to electron-donating substituents as a basis of 4-CH3 group.