• 설비공학논문집
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• 제21권7호
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• pp.373-379
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• 2009

In this study, frosting experiment was conducted to investigate the characteristics of frost formed on heat exchanger fins of non-uniform temperature distribution. Temperature distribution and frost characteristics of a 2-D fin surface were investigated in the airflow direction and the direction perpendicular to airflow. Temperature gradient was very small in the airflow direction, while it was large in the direction perpendicular to airflow due to fin heat conduction. The variations of the frost thickness gradient and the frost density gradient in the direction perpendicular to airflow were significant. On the other hand, the temperature gradient on frost surface in the direction perpendicular to airflow was significant at the early stage of frosting, while it decreased gradually as time elapsed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.465-470
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• 1998

A cross-flow fan often generates discrete noise call blade passing frequency tones. Several methods have been investigated to reduce this BPF noise, where the random distribution of blades is the most promising one. A simple and effective algorithm to determine a random distribution of blades is proposed which considers fan. performance as well as noise characteristics. The proposed method is verified by a simple numerical model and is applied in manufacturing cross-flow fan samples. Also some experiments are carried out and the experimental results are analyzed.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.86-90
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• 2003

This paper describes the electrical characteristics of Nomex paper employed as an insulating material for distribution transformers. The relative permittivities (dielectric constants) and tan$\delta$ (dielectric dissipation factors) were measured as dielectric characteristics and the partial discharge inception voltages (PDIVs) and breakdown voltages were also measured as electrical strength characteristics of Nomex paper. As a result, the permittivity and tan $\delta$ of Nomex paper demonstrated both temperature and frequency dependency. Of particular note, the permittivity of 0.18 mm Nomex paper was 2.4 according to the ASTM condition, The PDIVs and breakdown voltages were almost linearly increased with the thickness of Nomex paper. Furthermore, its electrical strength was superior to conventional Kraft paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.81-85
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• 1991

The distribution facilities fault has been anually shown about 13% all of the total distribution faults. Therefore, to prevent, the distribution facilities we have to manage them properly during their life time and enhance their quality and advance preventible maintenance, that is predictive maintenance or condition based maintenance. This paper presents the aging characteristics and the degenerating factors. Accordingly, improving the enhanced quality of distribution facilites is expected to contribute the electric power operation constantly.

• 한국생산제조학회지
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• 제21권6호
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• pp.903-909
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• 2012

This study analyzed the temperature distribution in DPF with five partitioned electric heaters. The temperature distribution in DPF is an important design factor for regeneration and durability of filter. The design Factors that influence the temperature distribution in DPF there are several. In this study, the characteristics of temperature distribution in DPF were analyzed according to the following changes. First, the thermal conductivity of the filter was analyzed about effect on the durability of the filter. Second, the length from exhaust manifold to inlet of DPF was analyzed about effect on the temperature distribution in DPF. The boundary conditions of analysis has been verified with comparison to the results of existing experimental study and the numerical analysis. Based on the identified boundary condition, on assuming the condition of the actual driving, the temperature distribution in DPF was analyzed according to material properties of filter and the position of DPF.

• 전기학회논문지
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• 제57권12호
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• pp.2179-2185
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• 2008

This paper deals with the optimal investment method for distribution facilities, based on the analytical approach for the reliability assessment in distribution systems interconnected with new dispersed generations. The existing approach can estimate the expected reliability performance of distribution systems by a direct assessment of the configuration of the systems using the reliability indexes such as NDP(Non-Delivery Power) and NDE(Non-Delivery Energy). The indexes can only consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, this paper presents the new performance indexes for the investment of the distribution facilities considering both the expected interruption cost for the load section and the operation characteristics of dispersed generations. The results from a case study show that the proposed methods can be a practical tool for the voltage management in distribution systems including dispersed sources.

• 대한지리학회지
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• 제36권3호
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• pp.258-277
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• 2001

농협 연쇄점을 정보화로 인한 商的 유통의 합리화와 재고 집약형 대규모 물류센터의 다극화로 물적 유통 의 집약화가 이루어져 유통의 효율성을 높였고, 수송도 외부수주로 이루어지고 있다. 이에 따라 생활용품과 농산물의 배송방식은 각각 루트배송과 정시 일괄배송으로 상품의 특성에 따라 그 배송권이 형성되었다. 한편 상품 판매활동에 의한 공간적 특성은 답작농업의 발달과 서비스업 취업 정도에 따라 판매 상품류의 구성이 결정된다는 점이 밝혀졌다. 그러나 일상생왈 상품인 가공 식품류와 잡화류는 농협 연쇄점이 입지한 지역유형에 영향을 받지 않고 판매된다는 점이 규명되었다.

• Tribology and Lubricants
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• 제2권1호
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• pp.39-45
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• 1986

Wear simulation test have been conducted in mild, severe and transient wear regions by a four-ball wear tester. Wear particles are separatively deposited by the RPD technique, and quantitatively analysed in terms of wear particles size distribution. Characteristics of the wear particle size distribution are compare to the results of wear tests through both weibull parameters and center moment method of the weibull distribution function.

• 전기학회논문지
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• 제58권10호
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• pp.1855-1860
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• 2009

This paper caused a distribution utility to generation of analysis fault several cases on the ground of substation in a energy meter three phase current, voltage data measurement to fault type and characteristics. Mother wavelet transformation of suitable to method algorithm from the distribution utility to generation of fault in image impedance etc several parameter for utility characteristics effective to probatory fault point extraction.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3910-3917
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• 2021

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.