• Journal of IKEEE
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• v.22 no.3
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• pp.870-873
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• 2018

This paper presents the high frequency resonant inverter using ZVS(Zero Voltage Switching) known as the soft switching technology, which can reduce the turn-on and turn-off switching losses. Also, the analysis of the proposed resonant inverter is described by adopting normalized parameters, and its operating characteristics are evaluated according to the switching frequency and parameters. An example of 1.3[kW] IH-Jar design technique is presented based on the characteristic values obtained from the theoretical analysis. To prove the validity of the theoretical analysis, the experimental results using IGBT as the switching devices are additionally presented. In the future, it can be practically used in various power systems such as induction heating cooking, IH-Jar etc.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.190-196
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• 2020

The step to obtain a process dynamic model through process experiments is very important because it needs times and expenditures. Step response method is one of the standard methods to have long been used for understanding process dynamics, obtaining dynamical models and designing control systems. For the step response, it is usually required to measure process output for a step input change in the open-loop manner. Its disadvantage criticized is the long open-loop operation. For this, a method based on the time-optimal control technique to minimize the test time for obtaining the step response has been recently presented. However, the method requires iterative computations for the minimization of test times. Here, a method where iterative computations are not required is proposed. Simulation results are presented to show that test times to obtain step responses are reduced considerably and an autotuning method based on the proposed method is compared with the relay feedback autotuning method accepted widely for the autotuning of controllers.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.7-16
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• 2009

Provision of advanced warning information is one of the useful countermeasures to prevent traffic accidents. Analysis of user's preference for any information contents would be a backbone in designing more effective warning information systems. This study aimed at deriving more comprehensive and valuable warning information that leads to user's safer driving by conducting a questionnaire survey. In total, 258 people including various age groups and driving experiences participated in the survey. Preferable warning information contents were identified by this study. It is expected that the results would be useful data for providing warning information to drivers.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.362-362
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• 2011

터보분자펌프(turbo-molecular pump: TMP)는 고진공펌프 중의 하나로, 반도체/디스플레이 등 첨단 공정에서 진공 환경을 조성하는 핵심장비이다. 터보분자펌프(TMP)의 특성평가는 세계 여러 나라의 표준제정기구에서 제정한 국제규격에 그 기반을 두어, 한국표준과학연구원 진공기술 센터에서는 터보분자펌프(TMP) 특성평가시스템을 자체 설계/제작하여 그 신뢰성을 확인하기 위해 개발품 및 상용품 평가에 주력하고 있다. 터보분자펌프(TMP)는 보조펌프(backing pump)의 지원을 받으므로 보조펌프(backing pump) 용량에 따른 터보분자펌프(TMP)의 배기속도를 측정하고자 한다. 국제규격에서 제시하는 보조펌프 (backing pump)의 용량이 일정이상 작을 경우, 터보분자펌프(TMP)의 배기속도 및 압축비에 대해 감소함을 제시한다. 이 영향은 전체 압력 범위에서 보조펌프(backing pump)의 배기속도가 일정 용량 이상이면 터보분자펌프(TMP)의 배기속도에 영향이 없음을 제시하며, 이에 본 연구에서는 국제규격에서 제시하는 보조펌프(backing pump) 용량에 대해 서로 다른 조건에 맞추어 터보분자 펌프(TMP)의 배기속도에 미치는 영향을 연구하고자 한다. 본 연구에서는 100m3/h, 10m3/h 의 서로 다른 배기속도를 가진 보조펌프(backing pump)를 선정하여 분자량이 다른 가스(N2, He, Ar 등)에 대한 압축비의 변화와 배기속도 측정에 관해 상관 관계를 제시하며, 100m3/h, 10m3/h 의 서로 다른 배기속도를 가진 보조펌프(backing pump)에 따른 터보분자펌프(TMP)의 배기속도 및 운전성능을 제시하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4723-4728
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• 2014

In this study, a thermoelectric module (TEM) and a diesel engine were modeled using 1-D commercial software AMESim, and the performance of the TEM was evaluated when the engine was operated under the NEDC driving cycle. The goal of TEM modeling was to investigate not only the waste heat recovery (WHR) rate and energy converting efficiency, but also the heat transfer rate by taking the materials characteristics into account. In addition, a diesel oxidation catalyst (DOC) was designed, and it was found that the waste heat recovery with TEM affects the activation of DOC and alters engine exhaust composition. The simulation indicated that the WHR using TEM is beneficial for decreasing the fuel consumption of vehicles, but the reduction in the exhaust temperature affects the activation of DOC, resulting in an approximately 14% increase in CO and HC emissions. Therefore, the effect of waste heat recovery on the automotive emission characteristics must be considered in the development of automotive engine WHR systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.82-93
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• 2006

In this paper, filters are designed to reduce transients overvoltage in inverter fed high-voltage large-capacity induction motor drive system. Design issues for a LCR filter at the inverter output terminals to reduce the dv/dt of the inverter output pulse and a RC filter at the induction motor input terminals to match the characteristic impedance between cable and induction motor are examined in detail. These filters are modeled to be suitable to high-voltage large-capacity induction motor. The performance of the filter is evaluated through simulation using EMTP(ElectroMagnetic Transients Program). We presented filters that used high voltage large-capacity induction Motor on the basis of this. Effect of the filter is analyzed for variation of the cable length. Characteristics of filters are analyzed to reduce harmonic in voltage waveform of induction motor input terminal. The switching surge voltage became the major cause to occur the insulation failure by serious voltage stress in the stator winding of induction motor. Filter for to mitigate transients overvoltage presents a required component in drive system of high-voltage large-capacity induction motor. Also, proposed filters are proved through simulation using EMTP.

• The KSFM Journal of Fluid Machinery
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• v.18 no.3
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• pp.46-52
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• 2015

Pump-turbine system is widely used by the hydropower industry for stabilizing the electrical grid in the vast growing economy of most developed countries. This study only investigates the Fluid-structure Interaction (FSI) analysis of the pump-turbine system at various operating conditions. The FSI analysis can show how reliable each component of the system is by providing the engineer with a better understanding of high stress and deformation points, which could reduce the lifespan of the pump-turbine. Pump-turbine components are categorized in two parts, pressurized static parts and movable stressed parts. The fixed parts include the spiral casing, top and bottom cover, stay vane and draft tube. The movable parts include guide vanes and impeller blades. Fine hexahedral numerical grids were used for CFD calculation and fine tetrahedral grids were used for structural analysis with imported load solution mapping greater than 90 %. The maximum equivalent stress are much smaller than the material yield stress, and the maximum equivalent stress showed an increasing tendency with the varying of operating conditions from partial to excessive at both modes. In addition, the total deformation of all the operating conditions showed a small magnitude, which have quite small influence on the structural stability. It can be conjectured that this system can be safely implemented.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1273-1278
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• 2008

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/ evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• Proceedings of the ESK Conference
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• 1993.10a
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• pp.89-99
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• 1993

원자력발전소 고장 및 불시정지 사례의 상당수가 시스템과 연계되어 인간에 의해 수행되는 운전, 유지보수, 관리와 관련된 인적오류에 기인하는 것으로 알려져 있다. 이러한 인적오류는 원자력발전소의 안전성과 효율성의 유지에 중요한 변수로 작용하며 불시정지에 의한 경제적 손실과 사회적 충격을 초래 하게 된다. 특히, 국내 원자력발전소가 외국설계라는 점과 인적요인에 대한 체계적인 평가가 이루어 지 지 않은 상태에서 운영중인 것을 감안하면, 인적요인의 국가별 차이에서 발생가능한 인적오류 유발요인 이 상존하고 있다고 할 수 있다. 이러한 인적오류의 중요성에 비해 국내 원자력 발전소의 인적오류에 대 한 연구는 지금까지 활발히 이루어지지 않고 있다. 본 연구에서는, 국내 원자력발전소에서 발생하는 인적 오류의 분석과 그 분석결과를 응용하기 위한 기술개발의 첫단계로, 기존 국외의 인적오류연구방법론 비교 분석, 국내 원전의 인적오류 발생현황 및 관련보고체계 분석, 등을 수행하여 국내 원자력발전소의 인적오류 분석 및 응용기술개발을 위한 연구개발 방향을 정립하였다. 기존 국외의 인적오류연구방법론 비교분석에서는, 인적오류에 대한 연구를 그 접근 방식에 따라 관리적 접근방식, 정량적 접근방식, 정성적 접근방식의 세가지로 분류하여, 각 접근방식에 대한 분석대상, 분석방식, 수행목적 등, 각 접근방식의 특징과 이에따른 실효성을 분석하였다. 그리고, 국내 원전의 인적오류 발생현황 및 관련보고체계분석에서는, 국내 원자력발전소에서 발생한 고장/정지 사건이 내포하고 있는 인적오류의 주요 형태를 파악하였으며, 또한, 인적오류연구 수행에 필수적인 인적오류사례원으로서 국내 원전에서의 인적오류 관련 보고체계에 대한 운용현황을 파악하고 그 유용성을 조사하였다. 이러한 연구를 통하여, 국내에 적용가능한 인적오류 분석기술개발 추진을 위한 제약 조건과 이러한 제약조건을 극복하고 인적오류 분석기술 수준을 향상시키기 위한 필요충분조건을 파악하였으며, 이 필요충분조건을 고려하여 인적오류 분석기법개발, 인적 오류 사례전파 및 자료관리 기술개발, 인적오류 사례수집 기술개발, 등을 주요 골자로 하는 인적오류 분석기술개발의 기본 방향을 설정하였다. 이와 아울러, 오류사례의 수집, 상세분석, 자료의 저장 및 응용을 위한 hardware 및 software 환경을 체계화하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.45-50
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• 2013

The reflector of infrared lamp is designed to the optimal circular shape through the analyses of lumination distributions with a triangular, rectangular and circular configurations of infrared lamps respectively by using Photopia. PLC is used to compare and amplify the difference between soldering temperature profile and feedback value. It is fed to IR lamp controller which adjusts the soldering temperature of PV cell. The soldering temperature measured using an infrared temperature sensor is then fed back to the PLC. The closed control loop of soldering temperature on a PV cell is implemented. The noncontact soldering device of PV cells using infrared lamp which is easily operated by HMI operation panel and controlled robustly by PLC and IR lamp controller is developed.