• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.36-46
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• 2008

This paper is to study on the Construction of Test circuit and Unification of Experiment Method for high voltage gas-insulated load switch using high power testing system The high power testing system is a equipment to verify electrical and mechanical performance on electrical product. The system consist of short-circuit generator, back-up breaker, making switch, impedance, high voltage transformer, low voltage transformer, measuring and protection system, etc. Using this system, we can test related to high power, for example, short-time current test, active load Current test, magnetizing Current test, capacitive current test, closed loop current test, etc. Standards of high voltage gas-insulated load switch that is in use domestic distribution line are ES 5925-0002, IEC 60265-1, IEC 62271-1 and IEEE C 37.74, etc. In this paper, we standardized on the test procedure, organization of test circuit and analysis of measured data prescribed many difference standards, and applied this test method to 600[MVA] high power testing system. So that we can test the load switch satisfied standards.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.96-103
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• 2008

In this paper, a new algorithm based on sensitivity method for alleviating overloads in power networks is presented to find the switching branches effectively. By applying the new sensitivity of the line flow with respect to the change of the branch impedance, both on and off switchings for alleviating overloads in power networks are performed systematically at once and an effective scheme for drawing up a plan to alleviate overloads of the lines is presented through screening a large number of line switching cases easily. The ranking of switching branches is calculated according to the new switching algorithm based on sensitivity method and the switching of the ranked branches is performed in the order of ranking until overloads are eliminated. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus test system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1621-1628
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• 2003

Packaging structures to block the propagation of higher­order modes in the shielded microstrip lines are designed. Packaging for microwave circuits is necessary, basically, to isolate and protect circuits from outside environments both physically and electrically. The drawback of packaging is the possibility of higher­order mode propagation, similar to waveguide modes, as the operating frequency increases. One of Possible choices for the higher­order mode suppression is to insert diaphragms to the housing structure. The shielding effects of diaphragms are analyzed using an FEM code. Several parameters such as dispersion, mode conversion, and higher­order mode transmission and reflection are analyzed. The effect of higher­order mode suppression is eminent as the depth or width of a diaphragm is increased in the air region of the microstrip line. It is shown that inductive diaphragm structure can lower ${S_21}$ for the second­order mode incidence by 30㏈, comparing with the conventional capacitive diaphragm structure. Packaging structure analyzed in this paper can be applied usefully to the design of the microwave system in a package such as transmit/receive modules.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.23-28
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• 1999

Rectangular waveguide slot antenna which has simple structure, high efficiency, high trust and small size, is extending in a field of application such as many Radar and Microwave communication. A slot cut into a wall of waveguide is propagated electromagnetic wave to free space it interrtupts the flow of current inner conductor of waveguide. Therefore incident of slot, cutdepth, width, length, i.e. are important parameter of characteristic change of the slot antenna. Result from difficulty of theoretical analysis about slot frequently experimental measured data useful design and manufacture have been accomplished. In this paper, we find the suitable method of analysis that compare two analysis results with measured result of established literature - admittance of slot be solved by propagated power from electric field distribution of slot and mode current computation and accomplishment of computable chart which hasresonant length and cutdepth, incident of slot, i.e. and use the HFSS which applyed finite-element method obtain equal slot analyed method.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.602-606
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• 2008

LCD is supplied light by BLU(Back Light Unit) and the light represents color by each color filter. Also LCD adjusts the amount of light by controlling liquid crystal between the glass of upper plate and one of lower. However, it is impossible to completely exclude light due to the structural and physical characteristic of liquid crystal. Therefore, on transfering light through optical sheet and liquid crystal, many problems are generated. They are related with energy efficiency and get effective for the contrast of LCD to have lower contrast ratio than other display devices. To solve the problems, many techniques have been studied and developed but don't exist keys to solution for them. Among methods, local dimming is one example to be applied to LCD. In this paper we propose image processing algorithm for local dimming of BLU of LED used as light source. The proposed algorithm extracts maximum luminance signal and lights using each extracted signal on segmented region of BLU. Also the proposed algorithm generates image signal in corresponding to luminance of the segmented region and supplies them with LCD panel to represent image with improving luminance ratio.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.90-95
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• 2009

The application of a large power transformer into a power distribution system was inevitable due to the increase of power demand and distributed generation. However, the decrease of the power transformer‘s impedance causes the short-circuit current of the power distribution system to increase and thus, the higher short-circuit current exceeds the cut-off ratings of the protective devices such as a circuit breaker. To solve these problems, several countermeasures have been proposed to protect the power system effectively from the higher fault current and the superconducting fault current limiter (SFCL) has been expected to be the promising countermeasure. However, the current limiting effect of SFCL including its bus voltage drop compensation depends on SFCL's application location in a distributed power system. In this paper, the current limiting and the bus-voltage drop compensating characteristics of the SFCL applied into a power distribution system were studied. In addition, the quench and the recovery characteristics of the SFCLs in each location of the power distribution system were compared each other.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.267-267
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• 2006

전력에 큰 손실을 초래하는 고장전류를 차단하기 위한 한류기(FCL) 소재로서 고온 초전도체인 BSCCO 2212가 사용된다. 고온에서 용융된 BSCCO 2212 분말은 원심성형법에 의해 한류기용 튜브로 제조되었다. BSCCO 튜브의 기계적 특성을 높이고 용융온도를 낮추기 위해 $SrSO_4$(10wt-%)를 첨가하였다. 용탕은 $1200^{\circ}C$에서 완전히 용융되어 금속 몰드로 주입되었고 원심성형에 사용되는 금속 몰드는 $550^{\circ}C$ 온도로 2시간 예열 후 1020 ~ 2520 RPM으로 회전시켰다. 원심력에 의해 성형된 BSCCO 튜브는 약 48시간 동안 로에서 서냉 후 금속 몰드로부터 분리하였다. 튜브의 용이한 분리를 위해 이형제로서 BSCCO 2212 powder를 사용하였고 임계전류측정을 고려하여 Ag tape 단자를 튜브 끝단에 부착하였다. BSCCO 제조 공정에 있어서 몰드의 예열온도, 용융온도, 몰드 회전속도 등의 변수를 조절하여 최적의 조건을 확립하였다. 제조한 BSCCO 튜브의 임계전류($I_c$)와 임계전류밀도($J_c$)는 77K에서 536A와 $205A/cm^2$ 이었다. 본 연구에서는 BSCCO 2212 튜브를 제조하는 공정조건 변화와 각 조건에서 제조된 BSCCO 2212 튜브의 전기적 특성 및 그에 따른 분석에 대해 기술하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.175-185
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• 2019

The security control is to protect IT system from cyber infringement by deriving valid result values in the process of gathering and analyzing various information. Currently, security control is very effective by using SIEM equipment which enables analysis of systematic and comprehensive viewpoint based on a lot of data, away from analyzing cyber threat information with only fragmentary information. However, It can also be said that cyber attacks are analyzed and coped with the manual work of security personnel. This means that even if there is excellent security equipment, the results will vary depending on the user using. In case of operating a characteristic web service including information provision, This study suggests the basic point of security control through characteristics information analysis, and proposes a model for intensive security control through the type discovery and application which enable a step-wise analysis and an effective filtering. Using this model would effectively detect, analyze and block attacks.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1235-1242
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• 2018

When the wind speed changes rapidly, the wind turbine is stopped for the safety of the power system and the mechanical system. At that moment, the wind turbine gearbox is damaged and broken due to the contact load of the gearbox. In addition, the problems such as increasing frictional heat and deteriorate of the brake occur, because the power of the blades is transmitted directly to the brakes. This paper proposes a hybrid magnetic gear shape that solves the problem caused by the contact of the mechanical gear, which is the power transmission device of the wind power generation system, and the power cutoff system. The shape of the hybrid magnetic gearsuitable for the wind power generation system is derived through the torque and loss analysis according to the shape of the hybrid magnetic gear by using the two dimensional finite analysis method.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.66-72
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• 2019

The observation satellites which uses high heat-dissipating equipment such as synthetic aperture radar (SAR) satellites require a radiator to transmit heat from the equipment into outer space. However, during cold conditions it requires a heater to maintain the temperature of equipment within the allowable minimum limit when it is not in operation. In this study, we proposed a variable conductivity radiator that changes its thermal conductivity value through movement of the liquid metal between two reservoirs based on the temperature condition. This reduces the power consumption of the heater by limiting heat transfer path to the radiator in cold condition, while effectively transferring heat to the radiator during hot condition. The feasibility of the proposed radiator was validated through comparison of the thermal control performance with the conventional fixed conductivity radiator via a thermal analysis.