• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.14 no.3
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• pp.151-161
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• 2010

A reversed trapezoidal fin is analyzed using a two-dimensional analytical method. Heat loss from the reversed trapezoidal fin is presented as a function of the fin shape factor, fin base thickness and the fin base height. The relationship between the fin tip length and the convection characteristic number as well as that between the fin tip length and the fin base height for equal amounts of heat loss are analyzed. Also the relationship between the fin base thickness and the fin shape factor for equal amount of heat loss is presented. One of the results shows that the heat loss decreases linearly with the increase of the fin shape factor.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2215-2216
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• 2011

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to electrical railway vehicle is investigated from an electrical response point of view. To analysis voltage and current waveforms by induced contact loss phenomenon on driving electrical railway vehicle, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. Throughout prototype simulator and contact wire and catenary wire experiments, it is confirmed that current waveforms is distorted by contact loss phenomenon and in case of driving electrical railway vehicle.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1376-1382
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• 2010

The propulsion Motor system has changed from the DC motor system to the induction motor system. Although the induction motor system has almost reached the stage of maturity, this system also need changed to the IPMSM system for direct drive without reduction gear. Thus, the IPMSM(Interior buried Permanent magnet synchronous Motor) has been adopted to meet the driving specification. In this paper, loss characteristic analysis of IPMSM has been performed using adopted F.E.M.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.75-75
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• 2008

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.450-453
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• 2003

This paper presents the estimation on Load Characteristic Factor(k) which is considered to load pattern and seasonal characteristic of consumer. We can calculate the loss of distribution networks through the equation composing of Load Factor(LF), Loss Load Factor(LLF) and load characteristic factor(k). This equation is similar to the method of Regulator-General Victoria, Australia. Generally, the conventional method for calculating the distribution losses uses k with a constant value from 0.1 to 0.3. However, the k which is a relationship between LF and LLF can be varied by load pattern and seasonal characteristics. It is necessary to estimate the k according to load characteristics. This paper shows the result for recalculating k using the KEPCO's SOMAS data measured in distribution networks.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.427-431
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• 2009

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to high-speed trains are investigated from an electrical response point of view. To analysis power line disturbance by induced contact loss phenomenon for high speed operation, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. One of the most important needs accompanied by increasing the speed of high-speed train is reduced that an arc phenomenon by loss of contact brings out EMI. In case of a high-speed train using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI(Electromagnetic Interference), dummy signal injection etc usually occurs. Throughout experiment, it is verified that an arc phenomenon is brought out for simulator operation and consequently conducted noise is flowed in electric circuit by power line disturbance.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.603-607
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• 2009

About a Structure is performance external insulation is fundamantal performance for enrgy-saving. these day, most of residential structures have constructed by internal insulation method structure. The method structure internal insulation have construction and economical efficiency, but on the other hand, be generated heat loss by heat bridge especially, be generated loss heat-energy logical consequence in structure ondol. The external insulation structure method has a mert able to minimum to loss heat about heat-bridge. But the external insulation technique is unsatisfactory statues within the know-how and method of construction and materials compared with developed countries. The recently, the requirement of market related to the external insulation technique is resulted by the energy efficiency system, but it can lead to the lack of alternative technique In study on the korea type passive house building design for insulation block method of wall system has to experimental characteristic heat-energy of practice building. In result field-experimental, the heat-bridge appeared to characteristic spent heat-energy of blow 2L class and have a suffience performance it.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.37-42
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• 2007

We are developing a 22.9 kV/25 MVA superconducting fault current limiting(SFCL) system for a power distribution network. A Bi-2212 bulk SFCL element, which has the merits of large current capacity and high allowable electric field during fault of the power network, was selected as a candidate for our SFCL system. In this work, we experimentally investigated important characteristics of the 190 kVA Bi-2212 SFCL element in its application to the power grid e.g. DC voltage-current characteristic, AC loss, current limiting characteristic during fault, and so on. Some experimental data related to thermal and electromagnetic behaviors were also compared with the calculated ones based on numerical method. The results show that the total AC loss at rated current of the 22.9 kV/25 MVA SFCL system, consisting of one hundred thirty five 190 kVA SFCL elements, becomes likely 763 W, which is excessively large for commercialization. Numerically calculated temperature of the SFCL element in some sections is in good agreement with the measured one during fault. Local temperature distribution in the190 kVA SFCL element is greatly influenced by non-uniform critical current along the Bi-2212 bulk SFCL element, even if its non-uniformity becomes a few percentages.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.54-60
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• 2013

Numerical analysis of the radiant heat characteristic around heatsink according to arrangement and shape of fin on 60W-LED lamp is conducted in this study. In the case of top blow blowing from upper side on LED lamp, there is just little difference in cooling characteristics according to the height of fin. On the other hand, the fin arranged side by side has the advantage of heat transfer enhancement by comparing with zig-zag type because it leads to more loss of flow. In case of making fin round to increase the amount of heat transfer, designing arrangement with the minimized loss of flow has the advantage of characteristic.

• International Journal of Quality Innovation
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• v.2 no.1
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• pp.50-57
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• 2001

The economic design of specification limits must be determined on an economic basis where we minimize total loss to society, which consists of both the producer and the consumer. Economic specification limits have been developed based on the assumption that the quality characteristic is normally distributed. Unfortunately, the assumption is not to meet some practical cases. In this paper, some non-normal distributions are considered for quality characteristic with geometrical features. An economic model for selecting the optimum specification limits on the basis of minimizing total cost is introduced. A case study is presented to illustrate the application in practice.