• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.70-74
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• 2014

An Operating Experience Report(OER) has written about events and accidents happened at a Nuclear Power Plant(NPP). The purpose of publishing the OER is to prevent the similar event or accident repeatedly by spreading the experience of a single plant to other plants personnel. In this paper, it is analyses that the foreign NPPs' OERs on JIT published by the International Nuclear Agency(WANO, INPO, COG, BE). The analysis introduced in this paper is performed along with the various factors such as type of work, root-cause, and equipment. The root-cause analysis about the OERs shows that the Human-error is the major factor in foreign NPPs, but on the other hand equipment problem is the main part of the Domestic NPPs. The ratio of the foreign NPP's OERs on JIT according to the type of work was applied to KHNP-JIT developed nowadays for the first time in KOREA.

• Journal of Biosystems Engineering
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• 제30권3호
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• pp.141-146
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• 2005

Worldwide consumption of vegetable soybean has been increasing recently, but, in the process of vegetable soybean production threshing and seperation work accounts for about $80\%$ of overall labor. Therefore, developing of the vegetable soybean thresher is necessary to reduce the cost of labor. The main objective of this study is to develop the vegetable soybean thresher which is suitable for domestic circumstances. The threshing and separating performance, operating cost, and field capacity of developed vegetable soybean thresher are investigated and analysed. The results are as follows. The effective field capacity of the developed vegetable soybean thresher was shown as 4.8hr/10a, and reduced as much as 11.7 times compared with human labor. The ratio of unthreshed soybean-pod to stem after threshing work was shown as $1.5\%$ and the damaged pod ratio of detached soybean was shown as $1.8\%$. The cost of human labor was shown as 2,560,000 won/ha, but the operating of the developed vegetable soybean thresher was shown as 503,000won/ha. If the vegetable soybean thresher would be used in our farm, the minimum cultivation area appeard to be 22.7a for the cost effective management.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.860-868
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• 2018

This article presents a new design of earthquake instrumentation that is suitable for quick decision-making after the seismic event at the nuclear power plant (NPP). The main objective of this work is to ensure more availability of the NPP by expediting walk-down period when the seismic wave is incident. In general, the decision-making to restart the NPP after the seismic event requires more than 1 month if an earthquake exceeds operating basis earthquake level. It affects to the plant availability significantly. Unnecessary shutdown can be skipped through quick assessments of operating basis earthquake, safe shutdown earthquake events, and damage status to structure, system, and components. Multidecision parameters such as cumulative absolute velocity, peak ground acceleration, Modified Mercalli Intensity Scale, floor response spectrum, and cumulative fatigue are discussed. The implementation scope on the field-programmable gate array platform of this work is limited to cumulative absolute velocity, peak ground acceleration, and Modified Mercalli Intensity. It can ensure better availability of the plant through integrated decision-making process by automatic assessment of NPP structure, system, and components.

• Nuclear Engineering and Technology
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• 제50권7호
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• pp.1006-1016
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• 2018

Since the early forties, researchers from around the world have been studying the phenomenon of deadtime in radiation detectors. Many have attempted to develop models to represent this phenomenon. Two highly idealized models; paralyzable and non-paralyzable are commonly used by most individuals involved in radiation measurements. Most put little thought about the operating conditions and applicability of these ideal models for their experimental conditions. So far, there is no general agreement on the applicability of any given model for a specific detector under specific operating conditions, let alone a universal model for all detectors and all operating conditions. Further the related problem of pile-up is often confused with the deadtime phenomenon. Much work, is needed to devise a generalized and practical solution to these related problems. Many methods have been developed to measure and compensate for the detector deadtime count loss, and many researchers have addressed deadtime and pulse pile-up. The goal of this article is to summarize the state of science of deadtime; measurement and compensation techniques as proposed by some of the most significant work on these topics and to review the deadtime correction models applicable to present day radiation detection systems.

• 한국생산제조학회지
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• 제6권4호
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• pp.130-137
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• 1997

The demand for wire-cut EDM is increasing rapidly in the die and tool making industry. In this study machining characteristics such as machining rate, surface roughness, hand drum form and hardness of machined material are investigated experimentally under the conditions varing pulse on time, pulse off time, peak voltage, wire tension after fixing other conditions in SKD 11 and brass and brass workpiece. It was found that various operating conditions had significant influences on machining characteristics. But the hardness of workpiece was uneffected by operating conditions. Also it was obtained experimentally that brass workpeice had better machinability than SKD 11 one.dition according to the current(Ip) in an electric spark machine : 1) Electrode is utilized Cu and Graphite. 2) Work piece is used the material of carbon steel. The condition of experiment is : 1) Current is varied 0.7(A) to 50(A) and the time of electric discharging to work piece in each time is 30(min) to 60(min). 2) After the upper side of work piece was measured in radius(5$\mu$m) of stylus analyzed the surface roughness to ade the table and graph of Rmax by yielding data. 3) Electro wear ratio is : \circled1Cooper was measured ex-machining and post-machining by the electronic balance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume $\times$specific gravity and analyzed to made its table and graph on ground the data. 4) In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V. R and the memory scope was sticked to the electric spark machine. 5) In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid , it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging.

• 터널과지하공간
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• 제32권2호
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• pp.93-106
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• 2022

본 연구에서는 광산 현장에서 트럭 운전자들이 스마트 기기를 이용해 원석 생산 데이터를 기록하고, 이를 이용해 PC 환경에서 작업일지(운행일지)를 작성할 수 있는 애플리케이션을 개발하였다. 이를 위해 국내에서 가행 중인 4곳의 광산을 연구지역으로 선정한 다음 현장에서 사용하고 있는 작업일지를 확보하였다. 광산별로 작업일지에 포함되는 정보 요소를 분석하였다. 광산별로 작업일지 작성을 위해 기록하는 정보와 양식이 서로 다르므로, 원석 생산 데이터 기록과 작업일지 작성을 위한 애플리케이션은 연구지역 맞춤형으로 4종을 개발하였다. 블루투스 비콘의 신호를 수신하는 방법과 사용자가 직접 애플리케이션을 조작하는 방법으로 원석 생산 데이터를 기록할 수 있다. 기록된 데이터 파일은 클라우드 서버에 업로드되고, 업로드된 파일은 PC 환경에서 작업일지 작성 애플리케이션에 의해 현장에서 사용하는 형태의 작업일지로 변환할 수 있다.

• 터널과지하공간
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• 제32권5호
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• pp.327-343
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• 2022

본 연구에서는 노천 및 지하 광산의 트럭 운반 작업에 대한 데이터를 기록하고, 이를 이용하여 운반 작업의 성능을 평가할 수 있는 표준 트럭 작업 일지를 개발하였다. 국내에서 가행 중인 5곳의 광산에서 활용하고 있는 작업 일지를 확보하여 분석을 수행하였고, 작업 일지에 포함되어야 할 항목들을 결정하였다. GMG (Global Mining Guidelines Group)에서 제안한 핵심성과지표(KPIs)들의 산정식을 분석하여 차량 운행시간을 기록하는 방법을 결정할 수 있었다. 국내의 석회석 지하 광산을 연구지역으로 선정한 후 표준 트럭 작업 일지를 이용하여 운반 작업의 성능을 평가하였다. 그 결과, 트럭의 가용률 측면에서 가동시간이 46.7%, 물리적 가용률과 기계적 가용률은 모두 100%로 나타났다. 이용률의 경우, 가용장비 이용률이 88.2%, 자산 이용률이 41.1%, 운영 이용률과 유효 이용률은 각각 88.2%와 79.2%로 나타났다. 효율성의 경우에는 운영 효율성이 89.9%로 나타났다.

• Journal of Mechanical Science and Technology
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• 제16권10호
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• pp.1287-1295
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• 2002

In this work, the fuel economy of a parallel hybrid electric vehicle is investigated. A vehicle control algorithm which yields operating points where operational cost of HEV is minimal is suggested. The operational cost of HEV is decided considering both the cost of fossil fuel consumed by an engine and the cost of electricity consumed by an electric motor. A procedure for obtaining the operating points of minimal fuel consumption is introduced. Simulations are carried out for 3 variations of HEV and the results are compared to the fuel economy of a conventional vehicle in order to investigate the effect of hybridization. Simulation results show that HEV with the vehicle control algorithm suggested in this work has a fuel economy 45% better than the conventional vehicle if braking energy is recuperated fully by regeneration and idling of the engine is eliminated. The vehicle modification is also investigated to obtain the target fuel economy set in PNGV program.

• 동력기계공학회지
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• 제18권4호
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• pp.60-65
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• 2014

In this paper, cycle performance analysis for heating capacity, compression work and COP of R134a supercritical heat pump is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include superheating degree, pressure and outlet temperature of gas cooler, compressor efficiency and evaporating temperature in the R134a supercritical heat pump system. The main results were summarized as follows : Superheating degree, pressure and outlet temperature of gas cooler, compressor efficiency and evaporating temperature of R134a heat pump system have an effect on the heating capacity, compression work and COP of this system. With a thorough grasp of these effect, it is necessary to design the supercritical heat pump using R134a. The prediction for COP of R134a supercritical heat pump have been proposed through multiple regression analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.637-640
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• 2009

The LCD based on Kerr effect is highly interesting because it uses an optically isotropic state with no need of alignment layer and it shows sub-millisecond response time. The problem of the device is that it requires very high operating voltage and the transmittance is relatively low compared with other LCDs that use nematic LC. In this work, we study on various electrode structures and driving method which can lower operating voltage.