• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.10-14
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• 2011

This paper suggests the method to calculate radiation limit of ISM(Industrial Scientific Medical) equipment in order to protect radio device in the situation that ISM equipment and radio device are operated in near distance. The factor for correction and protection ratio which is need for protecting radio device were considered to calculate radiation limit of ISM equipment. Also, the scenario which is required to limit radiation power of ISM equipment was referred and the S/W for calculation of radiation limit was developed by using GUI(Graphical User Interface) on Matlab. The suggested method for calculation of radiation limit of ISM equipment will be used to protect radio device from ISM equipment.

• Advances in materials Research
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• v.9 no.2
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• pp.115-131
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• 2020

Limit elastic speed analysis of Al/SiC-based functionally graded annular disk of uniform thickness has been carried out for two cases, namely: metal-rich and ceramic rich. In the present study, the unknown field variable for radial displacement is solved using variational method wherein the solution was obtained by Galerkin's error minimization principle. One of the objectives was to identify the variation of induced stress in a functionally graded disk of uniform thickness at limit elastic speed using modified rule of mixture by comparing the induced von-Mises stress with the yield stress along the disk radius, thereby locating the yield initiation. Furthermore, limit elastic speed has been reported for a combination of varying grading index (n) and aspect ratios (a/b).Results indicate, limit elastic speed increases with an increase in grading indices. In case of an increase in aspect ratio, limit elastic speed increases up to a critical value beyond which it recedes. Also, the objective was to look at the variation of yield stress corresponding to volume fraction variation within the disk which later helps in material tailoring. The study reveals the qualitative variation of yield stress for FG disk with volume fraction, resulting in the possibility of material tailoring from the processing standpoint, in practice.

• 전기의세계
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• v.15 no.1
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• pp.14-19
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• 1966

Transient stability analysis of Yongwol-Bupyong power system, which contains Yongwol steam power station, the largest one in Korea, was undertaken by using the Yonsei 101 Analog computer. The critical switching time and phase angle for the present 150MW power flow to be stable were found. And the transient stability power limit for the system was also found. It is concluded that the system becoms unstable if the power flow increases much more than 151MW.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.285-291
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• 2003

Switched reluctance machine has much attention as a traction drive because of high efficiency, high power and DC series torque characteristics. But the motor has to have a regenerative mode when it is adopted in electric vehicle and current divergence during the regeneration makes difficulties in the control. This paper proposes a reference current limitation strategy for a stable regeneration based on simulations and experimented tests. The motor is operated with conventional current limit and switching angle control method in motoring mode. Simulations and experiments are excuted to verify the feasibility of the proposed method.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.3
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• pp.78-84
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• 1994

The location of periodic noises in phase of AC power wave reveals to be specific according to the noise kinds which can be generally classified into modulation and baseband types in DLC. The former noise type has constant noise phase which is originated from switching mode power supplies and the latter normally caused from thyristor circuit of low switching frequency is compared to be more dispersive than the other.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.122-124
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• 1987

This paper presents a new algorithm in formulating a performance index for contingency selection method considering voltage security. Security limits defined-in terms of real power line flows and voltage magnitudes are considered in normalized subspaces where in critical contingencies are identified by a filtering algorithm using the infinite norm. Two types of limits, warning limit and emergency limit, are introduced for voltage and line flow. Usually performance indices have been constructed for real power line flows and voltages with each different criterion. This paper, however, presents a method that constructs them with the same criterion in use of the norm properties, so that we can assess security considering both of them. Rapid contingency simulation is performed using one iteration of fast decoupled load flows with LMML(Inverse Matrix Modification Lemma).

• 전기의세계
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• v.24 no.5
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• pp.97-102
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• 1975

This paper describes the result of a Study for the Optimum Operating method with Spinning reserve in case of outage of large generator unit to improve the system stability and prevent the system frequency drop. This is usually done by governor free operation, so we focused our attention to the operating Char acteristics of spinning reserve. Nexy, a study was made to mesure the upper limit of Spinning reserve and when this upper limit cannot match the required power, a relationship between the amount of spinning reserve and that of the load shedding requirement was searched with regard to several system operating conditions to use it in our future system operation. By this study, the optimum system operating method was recommended for reliable operation of power system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.447-450
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• 2004

This paper presents the basic application idea of superconductor cable for voltage stability limited power system. In bulk power system, the transfer capability of transmission line is often limited by the voltage stability, and superconductor cable could be on of the countermeasure to enhance heat transfer limit as well as voltage stability limit. Steady state voltage stability approach by P-V curve is used to calculate the maximum transfer capability of initial system and superconductor applied system IEEE-14 bus system is used to demonstrate its applicability.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.222-226
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• 2016

This paper investigated the trench process, unified field limit ring, and other products for the development of a 500 V-level unified trench gate power MOSFET. The optimal base chemistry for the device was found to be SF₆. In SEM analysis, the step process of the trench gate and field limit ring showed outstanding process results. After finalizing device design, its electrical characteristics were compared and contrasted with those of a planar device. It was shown that, although both devices maintained a breakdown voltage of 500 V, the Vth and on-state voltage drop characteristics were better than those of the planar type.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.48-55
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• 2019

With recent rapid increases in the power generation capacity of offshore wind power generators, reliable structural analysis of the large-scale infrastructure needed to install wind power generators at sea is required. Therefore, technology for heavy marine equipment such as barges and excavation equipment is needed. Under submarine conditions, rock drilling technology to install the substructure for offshore wind pile excavation is a very important factor in supporting a wind farm safely under dynamic loads over periods of at least 20 years. After investigating the marine environment and on-site ground excavation for the Saemangeum offshore wind farm, in this study we suggest.