• Journal of Ocean Engineering and Technology
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• v.10 no.2
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• pp.20-27
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• 1996

Ice loads can determined by many factors like ice properies and dimension, velocity and type of structures. The magnitude of ice load varies with the failure mode which can be predicted by failure maps if the aspect ratio and strain rate are known. To reduce the ice force, various types of structure have been investigated and it is now known that the identor shape plays an important role in reducing ice load on Arctic offshoe structures. The conical and wedge structures are good applied examples in the Arctic region. In this study, ice forces on single wedge indentors are investigated for crushing failure mode. The ice loads on wedged indentors are compared with those on cylindrical structures. Also the concept of "ice annual"is introduced to verify the ice loads to multi and single wedge structures.tructures.

• Journal of the Korean housing association
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• v.11 no.1
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• pp.159-169
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• 2000

This study was examined the energy conservation and the environmental value through the computer simulation employing the micro cogeneration system and the photovoltaic power generation system in house. The results of this study were as follows:1. In case of the micro cogeneration system. With the conditions of 'the electric produced by the micro cogeneration system was not sold to the electric power company', 'control quantity of commercial power supply was 10%' , 'operating time was 6 hour', 'minimum load rate of generator was 50%', and 'having a storage tank', the micro cogeneration system was superior compare to the comparative system in 2.4% of the energy conservation and 4.18% of the environmental value. 2. In case of the photovoltaic power generation system. 1) The 66.9% of total generated electric power from the photovoltaic power system was sold to the electric power company. That is, it could help to preserve the electric power from commercial power supply.2) There is a possibility of cutting the fair rate of electric power.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.339-344
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• 2011

Base station coordination has received much attention as a means to reduce the inter-cell interference in cellular networks. However, this interference reducing ability comes at the expense of increased feedback, backhaul load and computational complexity. The degree of coordination is therefore limited in practice. In this paper, we explore the trade-off between capacity and feedback load in a cellular network with coordination clusters. Our main interest lies in a scenario with multiple fading users in each cell. The results indicate that a large fraction of the total gain can be achieved by a significant reduction in feedback. We also find an approximate expression for the distribution of the instantaneous signal to interference-plus-noise ratio (SINR) and propose a new effective scheduling algorithm.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1312-1314
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• 2000

In this paper, voltage control APF(Active Power Filter) is introduced to improve power factor and reduce harmonic, generated from nonlinear load. The voltage controlled APF which is consisted of inverter and passive filter operates with nonlinear load simultaneously. According to the results of simulation, it is proved that the proposed system has the performance of improving power factor and reducing harmonics.

• International Journal of Railway
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• v.6 no.1
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• pp.13-25
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• 2013

Railpad prevents damage of the tie and ballast by reducing the impact and high frequency vibration, which occurs when a vehicle load transfers to a tie. But elasticity of the railpad can decrease under vehicle load and over usable period. If that happens, railpad will become stiffer. Increase in stiffness of the railpad also translates into a rise in track maintenance cost because it accelerates the damage of the track. In this study, accelerated heat ageing test was performed to predict an expectable lifetime of the railpad. As a result, it was predicted to be about sixteen years at $25^{\circ}C$ that life time of railpad using NR rubber from Arrhenius relationship. Also, it was predicted to be about thirty-two days at $100^{\circ}C$. At this time, a standard rate of thickness change is approximately within 12%.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.1
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• pp.1-8
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• 1985

The buckling characteristics of cylindrical shells with a circular hole, under axially compressed loads, have been analyzed and the results have been compared with existed experimental results. Deflection function with decay factor is assumed, and stress distribution around a circular hole in tensioned infinite plate is used for formulating buckling energy function. Applying Rayleigh Ritz procedure to this energy function, characteristic equation of eigenvalue problem is determined. Buckling load is defined by the minimum value of eigenvalues calculated according to several decay factors, and as the radius ratios of a circular hole (a/R) and shell thickness ratios (R/t) are varied, the reducing characteristics of buckling load are studied. As a result, buckling loads are reduced by about 50% according to some radius ratios ($a/R{\geq}0.15$) of circular hole and are not nearly affected by shell thickness ratio(R/t).

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.277-283
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• 2019

We have examined minimization of the number of impurity particles by replacing the load-lock chamber materials of the chemical vapor deposition equipment through optimization of the pumping method in the deposition chamber. In order to reduce the number of impurity particles in the chamber, the load-lock spacer material was changed from monomer casting nylon to Torlon. Furthermore, we controlled the pumping speed and number of pumping ports, which resulted in a reduction in the impurity particle generation from 2.67% to 0.52%. This study revealed that the selection of the material for the parts of a chemical vapor deposition chamber can minimize particle generation, thereby presenting a method of optimization method of the chemical vapor deposition chamber.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.577-583
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• 2011

In AC-PDP, it is necessary to achieve high luminance efficiency, high luminance and high definition by adopting technologies such as high xenon concentration and long gap. However, it is very difficult to apply above technologies because they make many problems such as mis-discharge and high driving voltage. Especially, the reactive power of PDP must be reduced for satisfaction in international standard IEC62087. In this paper, we proposed CLHS driving method which is half sustain driver without energy recovery capacitor. In the experimental results, CLHS driving method reduced reactive power consumption about 10%. Also, CLHS driving method improved the luminance efficiency in all discharge loads. Therefor, the more the discharge load decreases, the more the luminance efficiency improves. When the discharge load is 20%, CLHS driving method improved 5.35%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.69-77
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• 1998

The uninterruptible power supply (UPS) has become an integral part of modern computer and communication system to assure a continued and stable operation by providing an uninterruptible power to vital equipments. Various control methods have come to the fore in recent times with the advent of high frequency switching technologies. This paper describes the DSP control method for three phase UPS inverter which guarantees the sinusoidal output voltage under nonlinear load conditions. The proposed control scheme is verified by simulation and experiment.riment.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.375-377
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• 2000

In this paper, voltage controlled APF(Active Power Filter) is introduced to improve power factor and reduce harmonic generated from nonlinear load. The voltage controlled APF which is consisted of inverter and passive filter operates with nonlinear load simultaneously. According to the results of simulation, it is proved that the proposed system has the performance of improving power factor and reducing harmonics.