• Proceedings of the KIEE Conference
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• summer
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• pp.245-247
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• 2004

Stability is an important constraint in powr system operation. A new methodolgy that reduces the need for repeated simulation to determine a transiently secure operating point is presented. at cntingency , critical generator is limited generation to prevent rotor accelation until system is secured. when energy margin is zero, generation is degermined Implementation issues and simulation results are discussed in th context of a 23-bus system

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1103-1111
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• 1999

STACOM will be utilized to control substation voltage in the near future. Although STACOM shows good voltage regulation performance owing to its rapid and continuous response, it needs additional reactive power compensation device to keep control margin for emergency such as fault. ULTC transformer is one of good candidates. This paper presents a Kohonen Neural Network (KNN) based coordination control scheme of ULTC transformer and STACOM. In this paper, the objective function of the coordination control is minimization of both STACOM output and the number of switchings of ULTC transformer while maintaining substation voltage magnitude to the predefined constant value. This coordination, control is performed based on reactive load trend of the substation and KNN which offers optimal tap position in view of STACOM output minimization. The input variables of KNN are active and reactive power of the substation, current tap position, and current STACOM output. The KNN is trained by effective Iterative Condensed Nearest Neighbor (ICNN) rule. This coordination control applied to IEEE 14 bus system and shows satisfactory results.

• Journal of Chest Surgery
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• v.33 no.7
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• pp.581-584
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• 2000

Because the penetrating cervical tracheoesophageal injury may be associated with significant morbidity and mortality, it is important to choose the optimal method of diagnosis and management in patient with tracheoesophageal injury. We obtained a satisfactory result from repair of tracheoesophageal injuries using cardiopulmonary bypass. If the bleeding from the unidentified deep injury and the spread of infection could be controlled, the repair using CPB might increase the margin of safety during operation in the similar cases.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.15-20
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• 2005

We have achieved 180-degree angle of view performance using Super-PVA (S-PVA) technology first time in TFT-LCD industry. 82" full high definition ($1920{\times}1080$) TFT- LCD panel, the world's largest TFT-LCD, have been developed. In addition to the size breakthrough, this product achieves 600nits brightness, over 1200:1 contrast ratio, viewing angle free, 92% color gamut, and 8ms response time. Several key enabling technologies were developed to achieve these specifications, including two transistor direct driven independently controlled S-PVA subpixels, non even area ratio sub-pixels for optimal offaxis gamma, gate overlap driving for larger driving margin, new CCFL technology for higher color gamut, and advanced fabrication techniques including the use of Samsung's new $7^{th}$ generation line.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.159-170
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• 1998

Man-made noise in PCS frequency range are measured using the three axis antennal with common port and the measured data are statistically treated for modeling. The can optimal parameters of the measured APD curves can be calculated fast by using the Composite Approximation Algorithm. The calculated APD parameters can reduce the EM-environments Data Base memory and also be applied to determine the output and sensitivity margin of the transmitter and the receiver.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.7
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• pp.872-880
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• 1999

This paper presents an algorithm that can calculate the evaluation index of power system from the transfer capability point of view. The algorithm adopts a successive linear programming skill to solve an optimal solution. Two indices which are transfer margin index and economic matching index have been developed. Prior to calculating these indices, Maximum Load supplying Capability(MLSC) and Economic Load Supplying Capability(ELSC) are utilized as basic data. For man-machine interface, graphical user interface has been implemented so that an unified software package PSTCP(Power System Transfer Capability Program) has been developed. KEPCO systems planned up to 2006 year have been tested to show effectiveness and usefulness of the PSTCP for power system planning stages.

• Transactions on Electrical and Electronic Materials
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• v.3 no.4
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• pp.5-9
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• 2002

Chemical mechanical polishing (CMP) has become the preferred planarization method for multilevel interconnect technology due to its ability to achieve a high degree of feature level planarity. Especially, to achieve the higher density and greater performance, shallow trench isolation (STI)-CMP process has been attracted attention for multilevel interconnection as an essential isolation technology. Also, it was possible to apply the direct STI-CMP process without reverse moat etch step using high selectivity slurry (HSS). In this work, we determined the process margin with optimized process conditions to apply HSS STI-CMP process. Then, we evaluated the reliability and reproducibility of STI-CMP process through the optimal process conditions. The wafer-to-wafer thickness variation and day-by-day reproducibility of STI-CMP process after repeatable tests were investigated. Our experimental results show, quite acceptable and reproducible CMP results with a wafer-to-wafer thickness variation within 400$\AA$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.59-61
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• 2001

Polymeric suspended insulators for the electric track line have been developed. The main elements to design polymeric insulators are the insulation ability related with materials of FRP core and housing, and the optimal structure related with fitting parts and interface characteristics. To confirm the design fitness of insulator samples the electric field distribution by FEM and mechanical stress distribution by NASTRAN program was analysed with housing shed shapes and fitting structure. The leakage distance and breakage voltage properties which are core parameters to determine electric insulation ability are selected according to the requirement values of user specification, then the power frequency wet withstand voltage was specified above 22kV and the leakage distance was required above 290mm. The contamination condition of the electric track line was the heavy class according to IEC 815 in order to retain the enough safety margin against overvoltages.

• International Journal of Concrete Structures and Materials
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• v.7 no.4
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• pp.265-271
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• 2013

Prestressed concrete cylindrical pipe (PCCP) has been widely used for the distribution of water in communal, industrial, and agricultural systems for a long time. However, as it deteriorates, structural failures have been experienced. Replacing the entire existing PCCP with partial damages is not an economical method. Currently, as a cost effective repairing method, a new approach using fiber reinforced polymer (FRP) has been applied. A new design procedure of this method was proposed considering various kinds of loading condition. However, it is not easy to apply this method for design purpose due to its complex procedures. The objective of this study is to provide a new design criteria and process for PCCP rehabilitation with FRP. Through this method, the appropriate quantities of FRP layers will be decided after examining of limit states of deteriorated PCCP. For this purpose, two deterioration conditions are assumed; fully deteriorated and partially deteriorated. Different limit states for each case are applied to decide the quantities of attached FRP. The concept of "margin of safety" is used to judge whether the design results are within the optimal ranges to satisfy all limit states.

• Proceedings of the KIEE Conference
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• summer
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• pp.1385-1387
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• 2004

This paper presents a modelling methodology using fuzzy logic and train performance simulation for determining an economical running pattern for a high speed train which minimizes energy consumption under an given trip margin. The economical running pattern is defined with an economical maximum speed in traction phase, a speed at the end of coasting. As a case study, the simulation is carried out for an economical run of korea high speed train prototype, and the results of fuzzy model described.