• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.578-579
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• 2005

HVDC(High Voltage Direct Current) is an underwater cable between Jeju Island and Haenam in main land and supplies approximately 50% of electrical usage in Jeju Island. If there is any power failure due to HVDC, it will cost approximately 50,000 US dollars per day including Thermal Electrical Generation. Therefore it is absolutely necessary to recover the problem in rapid timely basis. In conclusion, new method and new systems(ULTRA #44 Model) are needed urgently to upgrade current HVDC underwater cable survey technique in Korea to minimize the cost and time factors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.721-723
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• 2005

This paper analyses the characteristic of temperature and energy of oil field cable in transient state such as lightning surge. For analysis in various conditions, many actual underground power cable systems are modeled using ATP These results are applied for the examination of temperature increase when the hitting of lightning surge are occurred. The inner part temperature of OF cable is analysed according to the various kinds of cable using the thermal model of transient state. The temperature increase of sheath and crossbonded lead by fault current is also analysed using IEC 60949.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1667-1669
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• 2001

The clack of Insulator, which results from internal or external surges such as electrical, mechanical, and thermal stress, might cause ground fault and a power failure without proper repairs. In order to minimize losses caused by a short-term or long-term power failure, it is necessary to detect the deteriorated insulator as early as possible. To do so, we will develop a new device, which can detect and trace an deteriorated insulator by monitoring its physical change the variation of frequency spectrum. This device will do so by finding a Periodic wave sharp (120 Hz), a peculiar wave generated by defused electricity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.731-733
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• 1999

Distributed Control System has been used for large scale and critical system control such as aerospace industries, chemical and power plant and so on. It is very impotant factors for design of the control system to be reliable and fault-tolerant. These control systems have backup or redundant processing modules for minimizing the time of failure and improving reliability. But such methods have changeover duration from faulty module to healthy one. During that interval, feedback control loop raises bumper and performance of the system become worse. TMR(Triple Modular Redundancy) control system is one of the best reliable ones that can overcome such a mortal drawback. This paper analyzes the components of TMR system functionally and proposes practical and cost effective configuration method for turbine control of thermal power plant.

• 한국주조공학회지
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• 제17권2호
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• pp.188-194
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• 1997

The effects of solidification condition and vibration on structure refinement were investigated for unidirectionally solidified $Al-CuAl_2$ eutectic composites. Eutectic composites were unidirectionally solidified under vibration with different growth rates (R) and thermal gradient(G). The lamellar structure was varied according to growth condition (G/R ratio). For the structure refinement the effect of G/R was found out to be greater than that of vibration. The interlamellar spacing(${\lambda}$) in this materials was varied with the growth rates(R) with "${\lambda}^2R$=Constant" relationship.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1553-1556
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• 2003

As the public use part of the railway and the road, the railway crossing is important to work properly by two transportation means. Also, It is important to provide the good face of friction on the railway crossing in aspect of protecting the railway crossing accident. Lately, the material of railway crossing panel is the wood. the asphalt, and the steel. As they have a various fault, it was studied to analyze the structural action of the new material. rubber panel. This paper analyzed eigenvalue, stress and displacement by truck passing weight and thermal stress using the FEM model.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.151-154
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• 2000

Used analog control systems have been converted into digital control systems due to performance degradation and difficulty of maintenance. There are few domestic DCS (Distribued Control System)s that have been applied to Bower plant. To apply a demestic DCS to power plant, the reliability, redundacny, and fault tolerance of DCS is important. Besides those items, the control action of control function block is also important. In this paper, we describe the requirements that PID control function block has to have, and implement a PID control function block that satisfies those requirements. Finally. simulation result using digital simulator for boiler system in thermal power plant shows the validity of a implemented PID control function block.

• 전기학회논문지
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• 제58권12호
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• pp.2311-2315
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• 2009

This paper presents a method to apply energy margin for assesment of total transfer capability (TTC). In order to calculate energy margin, two values of the transient energy function have to be computed. The first value is transient energy that is the sum of kinetic and potential energy at the end of fault. The second is critical energy that is potential energy at controlling UEP(Unstable Equilibrium Point). It is seen that TTC level is determined by not only bus voltage magnitudes and line thermal limits but also transient stability. TTC assessment is compared by the repeated power flow(RPF) method and optimization method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.145-150
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• 2003

In this paper we have studied the characteristics of temperature fields in a Molded Case Circuit Breaker (MCCB). A switch and a trip device are arranged in narrow space of the MCCB. Thus, thermal factors have been risen to important problem. The temperature rise means an energy loss and it becomes the reason of fatal fault in devices. Also, the temperature rise on the connection and the contact parts is regulated up to $115^{\circ}C$ and $105^{\circ}C$, respectively. Therefore, a study for preventing the temperature rise should be investigated. A numerical analysis method that has confidence might be preceded for this purpose. In order to verify the confidence of temperature field analysis, the results of the numerical analysis are compared with those of experimental one for the same model. Comparison results show a qualitatively good agreement within ${\pm}5%$ errors.

• 비파괴검사학회지
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• 제32권3호
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• pp.291-295
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• 2012

In the industrial field, real-time monitoring system like a fault early detection is very important. For this, the infrared thermography technique as a new diagnosis method is proposed. This study is focused on the damage detection and temperature characteristic analysis of ball bearing using the non-destructive infrared thermography method. In this paper, thermal image and temperature data were measured by a Cedip Silver 450 M infrared camera. Based on the results, the temperature characteristics under the conditions of normal, loss lubrication, damage, dynamic loading, and damage under loading were analyzed. It was confirmed that the infrared technique is very useful for the detection of the bearing damage.