• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.632-642
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• 2017

This paper presents an improved approach towards reducing the switching loss of insulated gate bipolar transistors (IGBTs) for a medium-capacity-class power conditioning system (PCS). In order to improve the switching performance, the switching operation is analyzed, and based on this analysis, an improved switching method that reduces the switching time and switching loss is proposed. Compared to a conventional gate drive scheme, the switching loss, switching time, and delay are improved in the proposed gate driving method. The performance of the proposed gate driving method is verified through several experiments.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.39-46
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• 2001

The plasma display panel with the electrode structure of new discharge AND gate was developed and the driving system for experiment was developed. And discharge AND gate operation was verified. Discharge AND gate operated by the operation speed of 8$mutextrm{s}$ and the operation margin of 20V. It was known to be able to control the discharge of the adjoining scan electrode accurately. Because this method uses the DC discharge, the control of the discharge can be facilitated compared with conventional discharge AND gate. Moreover, because the imput discharge and the output discharge of AND gate are separate, the display discharge can be prevented from passing AND gate. Therefore, it is possible to apply to the large screen plasma display. And the decrease of contrast ratio does not occur because the scanning electrical discharge does not influence the picture quality.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.202-209
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• 2000

This paper introduces the main function and protection method of IGBT gate driver that designed by KOROS. Recently, the applications of insulated gate bipolar transistors(IGBTs) have expanded widely, particularly in the area of railway converters. This driver is suitable for railway traction applications, so they are designed for circumstance of railway vehicle such as vibration. The input control power for this driver is supplied from battery charger of railway. it is no necessary an isolated power supply board or auxiliary power supply, with substantial savings in cost and space in railway applications. This gate driver can be used wide range of input voltage. So, performance of the driver has no relation with the battery voltage(70V∼110V). The protection methods of IGBT gate driver have many kind of ways, but this gate driver it designed to apply to converter for railway system, so this gate driver includes protection for arm short current and low control power voltage, etc. And the process of protection method and protection reference value are optimized by means of sufficient test with our own facilities.

• Progress in Superconductivity
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• 제13권1호
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• pp.47-51
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• 2011

Mono-atomic-layer graphene is an interesting system for studying the relativistic carrier transport arising from a linear energy-momentum dispersion relation. An easy control of the carrier density in graphene by applying an external gate field makes the system even more useful. In this study, we measured the Josephson current in a device consisting of mono-layer graphene sheet sandwiched between two closely spaced (~300 nm) aluminum superconducting electrodes. Gate dependence of the supercurrent in graphene Josephson junction follows the gate dependence of the normal-state conductance. The gate-tunable and relatively large supercurrent in a graphene Josephson junction would facilitate our understanding on the weak-link behavior in a superconducting-normal metal-superconducting (SNS) type Josephson junction.

• 한국항해항만학회지
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• 제41권3호
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• pp.119-126
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• 2017

컨테이너 선박의 대형화에 따라 컨테이너터미널 내에서 동일한 시간 내에 처리해야 하는 물동량이 계속적으로 증가하고 있다. 컨테이너터미널에서는 수동처리 방식의 한계를 극복함과 동시에 지속적으로 운영측면에서 발생하는 비용을 줄이기 위하여 컨테이너터미널의 자동화 시스템을 도입하고 있다. 왜냐하면 컨테이너터미널의 게이트 반출 입 업무를 수행함에 있어 수작업 처리 시 부정확한 자료 처리로 혼란 요소가 다소 발생하고 있다. 바코드 시스템에서 스캐너에 바코드를 직접 인식시켜야하기 때문에 처리 시간소요가 다소 길고 불편함 있어 이러한 문제점을 보안하여 게이트 자동화 시스템 RFID시스템은 차량 번호를 인식하는 기술을 이용하여 반출 입 처리 소요시간 단축하여 효율적인 게이트 업무 수행을 할 수 있다. 한편, 데미지 컨테이너 체크를 수동으로 진행하는 경우 게이트 반입 할때 컨테이너의 손상여부 확인 후 수기로 게이트 작업자가 직접 문서을 작성하여 보관하기 때문에 고객이 데미지 컨테이너 증거자료를 요청할때 증거자료로 제출하기에 불충분하여 고객으로부터 크레임을 받는 경우가 발생하였다. 또한, 게이트 작업자 및 인력에 의한 컨테이너 관리의 어려움 발생하였고 게이트 주변 인력의 컨테이너 관리 안전사고에 위험이 항상 노출되어 있었다. 본 논문에서 고찰하는 게이트 데미지 컨테이너 자동화 시스템을 도입하게 되면 영상 저장 시스템에 의한 컨테이너 관리가 가능하다. 컨테이너 손상정보가 시스템에 저장되어 있기 때문에 고객이 데미지 컨테이너 자료를 요청 시 시스템에 저장 되어 있는 데미지 컨테이너 영상을 검색하여 증거자료 제출이 가능하고 고객으로부터의 크레임 대비가 가능하다. 또한, 게이트 관리 인력 업무의 통합으로 인력 감소 및 게이트 부근 안전사고 위험이 감소하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1028-1031
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• 1997

The SS (Semi-solid) diecasters usually cany out the SS d~ecastmg experiments before producing new products. At the SS diecasting stages, the runner-gate part is always repeatedly corrected, which leads to a lengthened processing time and increased processing cost. The SS diecasting die design should consider component system factors. such as runner, gate, biscuit, overflow and airvent. A large amount of experience is essential in manual assessment and if the design is defective, much time and a great deal of efforts will be wasted in the modification of the d~e. Thus human negligence should be minimized. In this study, die design system for SS diecasting process has been developed to present algonthm of die design, especially runner-gate system. In addition, specific rules and equations for runner-gate system have been presented to avoid too many trials and errors with expensive equipment. It is possible for engineers to be efficient die design of SS diecasting and it will result in reduction of expense and time to be required. And we developed CAD system for SS diecasting die design by AutoLISP language under AutoCAD using proposed algorithm and the database. In addition, we developed the vector analysis program for filling pattern of SS metals.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The Korea-Japan Plastics Processing Joint Seminar
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• pp.33-39
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• 2003

Injection molding is widely used in producing various plastic parts due to its high productivity and the demand for high precision injection molded products is ever increasing. To achieve successful product quality and precision, the design of gating and runner systems in the injection mold is very important since it directly influences melt flow into the cavity. Some defects such as weld lines and overpacking can be effectively controlled with proper selection of gate locations. In the present study, the design of gate locations in injection molding of a dashboard for automobiles was carried out with CAMPmold, a PC-based simulation system for injection molding. A dummy runner was developed to simulate a runner system in order to increase the efficiency of the analysis. The numbers and locations of gates were varied in the present investigation as that an acceptable design was obtained in terms of reduced maximum pressure and clamping force.

• 한국생산제조학회지
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• 제26권3호
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• pp.299-305
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• 2017

Gate-lifting devices in small- to mid-sized sluice gates mostly employ the mechanical roller rack pinion (RRP) system. This RRP system, which consists of a rack-bar and a pinion, transforms a rotation motion into a linear one. The rack-bar has a series of roller trains that mesh with the pinion. In this study, we adopt an exact involute-trochoid tooth profile of the pinion to obtain a higher contact fatigue strength using the profile modification coefficient. Further, we determine the contact forces and investigate Hertz contact stresses to predict the pitting life of the pinion according to varying the shape design parameters. The results indicate that the design fatigue life of an RRP system for sluice gate can be achieved only when the design value of the profile modification coefficient reaches or exceeds a certain level.

• 산업경영시스템학회지
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• 제35권4호
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• pp.179-185
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• 2012

When manufacturing die casting mold, generally, the casting layout design should be considered based on the relation among injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects was differentiated according to the various relations of the above conditions. In this research, in order to optimize casting design of an automobile part (Gear Box) Computer Aided Engineering (CAE) was performed by using the simulation software (Z Cast). The simulation results were analyzed and compared with experimental results. During the mold filling, internal porosities caused by air entrap were predicted and reduced remarkably by the modification of the gate system and the configuration of overflow. With the solidification analysis, internal porosities caused by the solidification shrinkage were predicted and reduced by the modification of the gate system. For making a better production die casting tool, cooling systems on several thick areas are proposed in order to reduce internal porosities caused by the solidification shrinkage.

• 산업경영시스템학회지
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• 제38권1호
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• pp.44-51
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• 2015

When manufacturing die casting mold, generally, the casting layout design should be considered based on the relations of injection system, casting condition, gate system, and cooling system. According to the various relations of the conditions, the location of product defects was differentiated. High-qualified products can be manufactured as those defects are controlled by the proper modifications of die casting mold with keeping the same conditions. In this research, Computer Aided Engineering (CAE) simulation was performed with the several layout designs in order to optimize the casting layout design of an automotive part (Housing). In order to apply them into the production die-casting mold, the simulation results were analyzed and compared carefully. With the filling process, internal porosities caused by air entrapments were predicted and also compared with the modification of the gate system and overflow. With the solidification analysis, internal porosities occurring during the solidification process were predicted and also compared with the modified gate system. The simulation results were also applied into the production die-casting mold in order to compare the results and verify them with the real casting samples.