• Nuclear Engineering and Technology
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• 제31권5호
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• pp.476-485
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• 1999

In order to evaluate the gravity-injection capability to maintain core cooling after a loss-of-shutdown-cooling event during shutdown operation, the plant conditions of the Yong Gwang Units 3&4 were reviewed. The six cases of possible gravity-injection paths from the refueling water tank (RWT) were identified and the thermal-hydraulic analyses were performed using the RELAP5/MOD3.2 code. The core cooling capability was significantly dependent on the gravity-injection path, the RCS opening, and the injection rate. In the cases with the pressurizer manway opening higher than the RWT water level, the coolant was held up in the pressurizer and the system pressure continued increasing after gravity-injection. The gravity injection eventually stopped due to the high system pressure and the core was uncovered. In the cases with the injection path and opening on the same leg side, the core cooling was dependent on whether the water injected from the RWT passed the core region or not. However, in the cases with the injection path and opening on the different leg side, the system was well depressurized after gravity-injection and the core boiling was successfully prevented for a long-term transient. In addition, from the sensitivity study on the gravity-injection flow rate, it was found that about 54 kg/s of injection rate was required to maintain the core cooling and the core cooling could be provided for about 10.6 hours after event with that injection rate from the RWT. Those analysis results would provide useful information to operators coping with the event.

• 산업융합연구
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• 제20권12호
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• pp.145-153
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• 2022

본 연구는 중국 공기업의 세계화에 영향을 미치는 주요 요인을 실증분석한다. 선행연구를 바탕으로 초국적지수를 종속변수로 수출세 환급, 환율, 인적자원, 혁신능력, 자산운용능력, 대출능력, 기업발전단계, 글로벌 전개능력 등을 독립변수로 하는 회귀분석을 수행하였다. 실증분석 결과 수출환급금(E_tax)과 환율(E_rate)이 세계화의 외부영향요인에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 또한 인적자원역량(Edu, O_hunan), 혁신역량(R&D), 자금조달역량(Finance)은 공기업의 세계화를 위한 중요한 내부영향요인으로 나타났다. 공기업 전략수립에 있어 정부의 역할은 지도하는 수준에서 유지되어야 하며, 정부의 역할이 정부의 강제적인 관리 및 감독기능과 분리되어 공기업의 자율성이 제한되지 않도록 하여야 한다.

• Journal of Information Processing Systems
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• 제15권5호
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• pp.1131-1140
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• 2019

Characteristics of fruit tree canopies are important target information for adjusting the pesticide application rate in variable rate spraying in orchards. Therefore, the target detection of the canopy characteristics is very important. In this study, a canopy volume measurement method for peach trees was presented and a variable rate spraying system based on canopy volume measurement was developed using the ultrasonic sensing, one of the most effective target detection method. Ten ultrasonic sensors and two flow control units were mounted on the orchard air-assisted sprayer. The ultrasonic sensors were used to detect the canopy diameters and the flow controls were used to modify the flow rate of the nozzles in real time. Two treatments were established: a constant application rate of $300Lha^{-1}$ was set as the control treatment for the comparison with the variable rate application at a $0.095Lm^{-3}$ canopy. The tracer deposition at different parts of peach trees and the tracer losses to the ground (between rows and within rows) were analyzed in detail under constant rate and variable rate application. The results showed that there were no significant differences between two treatments in the liquid distribution and the capability to reach the inner parts of the crop canopies.

• 정보와 통신
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• 제11권8호
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• pp.60-77
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• 1994

This paper presents a survey of video coding schemes which use wavelet transform for the videophone on very low bit rate commun ication chan nel( ego 10 Kbps Public Service Telephone Network). Firstly, we introduce the standardization efforts to make the low bit rate videophone architecture and the typical application of low bit rate video coding scheme. Secondly, we summarize the several requirements on videophone, delay, encoder/decoder complexity, low bitrate, and progressive transmission capability. Third, we review the basic theory of wavelet transform without much mathematics. We compare the wavelet transform with short-time fourier transform and subband filters. Fourth, we summarize the video coding schemes proposed so far, and evaluate them with Ule requirements. Lastly, we conclude with fu¬ture research directions.

• 전기학회논문지
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• 제58권12호
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• pp.2505-2510
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• 2009

Semiconductor processes need measurement to confirm where there are problems in quality after progresses manufacturing process. This paper suggests equipment and automatic measure sampling method that control monitoring ratio according to change point occurrence availability of process that is not measure method by the existent simple ratio rate. This paper defines measure section as ailment section, metastable section and stability section by change point standard and create statistical model of each section and developed suitable measure rate model by section. As a result, we have accomplished maximum throughput and minimum sampling number that needs to maintain constant level of quality. Proposed method minimizes load of measure process by brings production quality sophistication and decrease of process badness and lowers measure rate in stable section making perception about problem occurrence quick heightening measure rate at change point occurrence.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.94-103
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• 1999

A model for the prediction of combustion and exhaust emissions of DI diesel engine has been formulated and developed . This model is a quasi-dimensional phenomenological one and is based on multi-zone combustion modelling concept. It takes into consideration, on a zonal basis ,detailed of fuel spray formation, droplet evaporation, air-fuel mixing, spray wall interaction, swirl , heat transfer, self ignition and burning rate . The emission model is considered with chemical equipment , as well as the kinetics of fuel. NO and soot reactions in order to calculate the pollutant concentrations within each zone and the whole of cylinder . The accuracy of prediction versus experimental data and the capability of the model in predicting engine heat release, cylinder pressure and all the major exhaust emissions on zonal and cumulative basis., is demonstrated. Detailed prediction results showing the sensitivity of the model bv various injection rates are presented and discussed.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.539-551
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• 2021

With the continuous increase of computational capacity, more and more complex nonlinear elastoplastic constitutive models were developed to study the mechanical behavior of elastoplastic materials. These constitutive models generally contain a large amount of physical and phenomenological parameters, which often require a large amount of computational costs to determine. In this paper, an inverse parameter determination method is proposed to identify the constitutive parameters of elastoplastic materials, with the consideration of both strain rate effect and temperature effect. To carry out an efficient design, a hybrid optimization algorithm that combines the genetic algorithm and the Nelder-Mead simplex algorithm is proposed and developed. The proposed inverse method was employed to determine the parameters for an elasto-viscoplastic constitutive model and Johnson-cook model, which demonstrates the capability of this method in considering strain rate and temperature effect, simultaneously. This hybrid optimization algorithm shows a better accuracy and efficiency than using a single algorithm. Finally, the predictability analysis using partial experimental data is completed to further demonstrate the feasibility of the proposed method.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2014년도 춘계 종합학술대회 논문집
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• pp.191-192
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• 2014

In this study, diagnostic model was proposed to evaluate and rate the innovation capability of SMEs and suggest alternatives to insufficient capabilities and optimum supporting programs for SMEs from literature survey, GIC model was composed based on KIS value and ASTI(Associate of Science and Technology information) SMEs database, thus, sample deviation can be caused and securing accurate data is insufficient. To compose model by analyzing characteristics of companies accurately, various companies' data for long period will be required.

• 한국국방경영분석학회지
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• 제30권1호
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• pp.153-167
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• 2004

This study focuses on building the wartime air operation model to evaluate the airfield capability. There are some uncertainties in the process of air operation such as mission flying time, turn around time, mission damage or kill rate, weather condition, and so on. Airplanes, on the way to the airbase after completing mission flight, may have been in queue on the holding point due to the unusable condition of airfield. And then, they may sometimes need to go other airbases due to the shortage of fuel. Under those uncertainties, this model is to evaluate the airfield capability in the wartime air operation using simulation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.624-627
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• 2004

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it according to its capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high Quality aggregate. Therefore, For solving the problems we apply to method of packaged dry combined materials for concrete using dried materials. That is to say that it is a kind of making into an instant. In this study, There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate's absorption following the rate of adding water, for using existing materials.