• 한국자동차공학회논문집
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• 제3권6호
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• pp.212-223
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• 1995

To improve the efficiency of a power transmission system with slip elements, power split/circulation system is applied. The performance of a power split/circulation system varies widely by the change of the followings; the layout of system, the type and gear ratio of planetary gear, the performance of slip element, etc. Therefore, when one designs such a power transmission system or when one determines the economic/power mode of system, a certain performance prediction method is needed. In this study, the internal power flow pattern of a power split/circulation system is theoretically analyzed on several transmission systems. And an effective performance prediction method(so called performance locus diagram) is presented. By this method, the effects of design factors can be easily understood and the qualitative performances of system can be clearly evaluated.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2789-2802
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• 2020

Small Modular Reactors (SMRs) are attracting wide attention due to their outstanding performance, extensive studies have been carried out for lead-based fast reactors (LFRs) that cooled with Lead or Lead-bismuth (LBE), and small modular natural circulation LFR is one of the promising candidates for SMRs and LFRs development. One of the challenges for the design small modular natural circulation LFR is to master the natural circulation thermal-hydraulic performance in the reactor primary circuit, while the natural circulation characteristics is a coupled thermal-hydraulic problem of the core thermal power, the primary loop layout and the operating state of secondary cooling system etc. Thus, accurate predicting the natural circulation LFRs thermal-hydraulic features are highly required for conducting reactor operating condition evaluate and Thermal hydraulic design optimization. In this study, a thermal-hydraulic analysis code is developed for small modular natural circulation LFRs, which is based on several mathematical models for natural circulation originally. A small modular natural circulation LBE cooled fast reactor named URANUS developed by Korea is chosen to assess the code's capability. Comparisons are performed to demonstrate the accuracy of the code by the calculation results of MARS, and the key thermal-hydraulic parameters agree fairly well with the MARS ones. As a typical application case, steady-state analyses were conducted to have an assessment of thermal-hydraulic behavior under nominal condition, and several parameters affecting natural circulation were evaluated. What's more, two characteristics parameters that used to analyze natural circulation LFRs natural circulation capacity were established. The analyses show that the core thermal power, thermal center difference and flow resistance is the main factors affecting the reactor natural circulation. Improving the core thermal power, increasing the thermal center difference and decreasing the flow resistance can significantly increase the reactor mass flow rate. Characteristics parameters can be used to quickly evaluate the natural circulation capacity of natural circulation LFR under normal operating conditions.

• 산업경영시스템학회지
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• 제30권1호
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• pp.48-58
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• 2007

For a sustainable development, the resources circulation system should be established and required alternative logistics area of enterprises. In this paper, we are to suggest a direction through analysis effects, and reduce, recycle, reuse factor of transportation, material handling, packing, information, management in logistics function, and effects of logistics organization on Firm Performance. We found significant correlations between the constructs extracted above, and between the constructs and firm's performance. This study was conducted with the subjects of manufacturing enterprises with concurrent reviews of literature and statistical analysis, and the meaning of this study would be the analysis of the influencers of the resources circulation system.

• 정보관리연구
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• 제39권2호
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• pp.163-184
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• 2008

본 연구에서는 선행연구에 대한 분석을 통하여 우리나라 대학도서관의 운영성과를 결정짓는 주요 변수들을 파악하고, 각 변수들이 운영성과에 미치는 영향을 실증적으로 검증함으로써 대학도서관의 경쟁력 실태와 장기적인 고객만족도 제고를 위한 시사점을 제공하고자 하였다. 구체적으로 본 연구에서는 도서관 서비스 활동에 대한 성과측정치 가운데 하나로 볼 수 있는 도서관 대출성과와 특성요인들(면적, 직원수, 장서수, 예산) 간의 관계를 분석하고 있다. 2004년부터 2007년까지 한국도서관협회에서 발간하고 있는 한국도서관연감에 포함된 통계 자료에 기초하여 이러한 관계를 종합적으로 분석한 결과, 대학도서관이 보유하고 있는 장서수와 도서관의 예산 규모 및 도서관 고유의 공간 면적 등과 같은 요소가 대출성과에 긍정적인 영향을 미치는 것으로 조사되었다(가설 1, 3 및 4 입증). 이와 같은 실증연구 결과는 대학도서관의 환경적 요소를 구성하는 도서관 면적이나 장서의 구입 및 개발 활동을 적극적으로 수행함으로써 대학당국을 만족시키고, 그러한 활동에 대한 투자(예산 지원)를 통하여 지속적인 도서관 활동(도서대출) 성과의 향상을 도모할 수 있을 것이다.

• 한국산학경영학회:학술대회논문집
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• 한국산학경영학회 2006년도 춘계학술발표대회 발표논문집
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• pp.103-123
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• 2006

환경문제 해결과 지속적 발전을 위하여 자원순환형 사회시스템이 구축이 논의되고 있으며 물류분야에서도 그 중요성이 부각되고 있다. 본 연구의 목적은 순환형 사회시스템 구축요인인 감량화, 재사용, 재활용과 기업의 물류운영 특성인 통합성, 혁신성, 대응성과의 관계 및 물류성과와의 관계, 이들 요소가 기업규모별로 물류성과에 미치는 효과와 그 영향요인을 분석하여 방향을 제시하고자 하는데 있다. 이 목적을 달성하기 위하여 제조기업을 대상으로 문헌연구와 실증연구를 병행하였다. 본 연구는 기존의 물류 연구들과 달리 자원순환형 사회시스템 구축요인과 물류운영특성이 물류성과에 미치는 영향을 분석하였다는데 의의가 있다고 하겠다.

• 대한기계학회논문집
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• 제9권5호
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• pp.579-589
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• 1985

본 논문의 모의 실험에 사용한 자연순환식 급탕 시스템과 지금까지 발표된 것 과의 차이점은 다음과 같다. 집열기의 집열성능 계산에 Close의 모델은 시스템의 평 균 온도를 이용하였으며, Mertol의 모델은 집열기의 성능을 일정하게 하여 자연순환식 급탕 시스템의 성능을 계산하였다. 그리고, Young의 모델은 집열기 입구 및 출구 유 체의 평균 온도로 집열기의 집열 성능을 계산하였다. Shitzer, Ong의 연구에서 밝혀 진 바와 같이 집열기 집열판의 온도와 유체 온도는 서로 다르므로, 본 논문에서는 이 것들에서 오는 오차를 줄이기 위해 집열기 순환 유체의 평균 온도와 집열판의 온도를 해석적으로 구하여 집열기의 성능과 순환 유체의 성질 계산에 이용하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2053-2058
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• 2008

It was investigated thermal performances on two array types of a serial circulation and a two-way parallel circulation for six water-cooled cold plates covered with non-metallic material (polycarbonate, PC) to reduce weight of the cooling devices for humanoid robot cooling. Six cold plates attached on $10{\times}10\;mm^2$ copper base : $0.5{\times}0.5\;mm^2$ pin-finned surfaces of 1.5 mm high with 0.5 mm array spacing, was mounted on six copper heating blocks with isothermal conditions of $50{\sim}90^{\circ}C$, respectively. In order to compare thermal characteristics according to two circulation types, the surface temperatures of heating blocks and the cooling water temperatures at inlets and outlets of cold plates were measured. From the results, it was found that a two-way parallel circulation was better performance than a serial circulation in terms of total thermal resistance, total heat transfer rate, and surface temperature rises from $1^{st}$ heating block to last one for six multiple cold plates.

• 한국유체기계학회 논문집
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• 제16권1호
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• pp.47-55
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• 2013

In the present study, a numerical simulation to analyze mixing performance inside an industrial mixer was investigated for various geometry of turbine impellers. Various pitching angles and various types of turbine blades were considered in the simulation. In order to model the rotation of impeller, the Multiple Reference Frames (MRF) technique was used. For evaluation of the effect of various shapes on the mixing performance, dimensionless coefficient such as flow coefficient, circulation coefficient, power coefficient, pumping effectiveness and circulation effectiveness were used. From the results, the effect of pitching angle of a pitched turbine impeller was to give best pumping effectiveness around $30^{\circ}$ pitching angle, whereas best circulation effectiveness around $65^{\circ}$ pitching angle. Dual pitched turbine impeller showed best performance in both pumping effectiveness and circulation effectiveness among impeller types considered in the present study.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.170-174
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• 2001

In this paper, CFD technique has been used at design stage to predict space air distribution in a cycle stadium with air circulation system. An air circulation flow of 0.67 rev./min was observed at computed results in the stadium space with and without air circulation system. Comparing the thermal comfort of the two models with or without air circulation system showed that the thermal environment in the former was superior in the latter. Energy savings could be achieved for the model with air circulation due to its lower air inflow temperature.

• 지식경영연구
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• 제5권2호
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• pp.53-65
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• 2004

Organizations continue to invest heavily in the acquisition of knowledge management systems (KMS). The overriding belief is that KMS-task fit will become more productive. A survey of users was conducted to better understand the factors that affect KMS-task fit to better explain KMS performance perspective on knowledge circulation process. This involves stating the research hypotheses among the following constructs: the characteristics of KMS, the fitness of task characteristics, and KMS performance. The findings indicate that the characteristics of KMS positively affect the fitness of task characteristics. The fitness of task characteristics are affecting KMS performance. The results of this study suggest that task-technology fit could be the basis for a strong diagnostic tool to evaluate whether KMS in a given organization are meeting user needs.