• Journal of Power System Engineering
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• v.15 no.2
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• pp.55-60
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• 2011

The popularity of diesel engines is derived primarily from their higher thermal efficiency resulting from higher compression ratio. NOx removal from the diesel emissions is very important to meet stringent emission regulations. NOx emission from diesel engines is removed by an urea-SCR or an LNT system. The urea-SCR system needs the urea-solution supply system with concentration and level sensor. This study was carried out to develop a sensor for the measurement of urea-solution concentration by an electric conductivity method. Considering experimental parameters were the material of electrode, two kinds of electric power(AC or DC), the distance between two electrodes, and the length of electrode. It was found that the AC electric power was more useful to measure the urea-solution concentration compared to DC, because it prevented an ionization of the urea-solution. The silver rod coated with Pt is the most useful electrode, tendency of which is similar to Pt rod, and the cost is more economic. We could also find out the optimum distance between two electrodes and the length of electrode was 10mm and 3mm, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.261-266
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• 1995

본 연구에서는 자기부상시스템에 대해 흡인식 자기부상방식을 채택하고 쇠구슬에 대한 운동을 상하 1자유도로 가정하여 운동방정식을 세운다. 이때 전자석이 자기 부상력은 전자석에 흐르는 전류와 인덕턴스의 함수라 가정하고, 모델의 불확실성은 자기부상계의 운동 방정식으로부터 선형화 할 때 발생하는 오차 및 파라미터 변동으로 생각한다. 또한 모델의 불확실성이 존재하더라도 정상편차 없이 부상하는 서보제어계를 설계한다. 그런데 저자등은 강인성 문제 및 정상편차 없는 것에 역점을 두어 H$_{\infty}$ 제어이론에 기초한 1형 로바스트 서보 제어기를 구하여 자기부상 시스템의 안정화 제어계로써 적용한 적이 있다. 이때 중심해 이외의 해를 이용하여 설계한 서보 제어계는 자기부상계의 과도상태시에 일어나는 오버슈트를 줄일 수 없었다. 따라서 시스템 내부 안정화를 위하여 H$_{\infty}$ 제어이론에 의해 설계된 피드백(feedback) 제어기와 물체가 부상할 때 오버슈트를 줄이고 제어량이 목표치에 잘 추종하기 위해 설계된 피드 포워드(feed forward) 제어기로써 2자유도를 갖는 제어계를 설계한다. 이렇게 설계한 2자유도 제어계를 가지고 모의 응답실험과 본 연구자들이 만든 자기부상 시스템의 실험결과를 비교함으로써 설계된 제어기의 타당성을 조사한다.

• Journal of the Korea Computer Industry Society
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• v.9 no.3
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• pp.99-104
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• 2008

The thermal stresses due to hydration heat in massive concrete structures are affected by ambient temperature and placing concrete temperature. It is needed to predict the thermal stresses considering ambient temperature and placing concrete temperature. In this study, hydration heat analyses of coping were carried out. After the maximum tensile stress was occurred at 2,75 days the crack index was increased. Therefore the possibility of crack occurrence was rare. The possibility of crack occurrence can be reduced by placing concrete temperature drop. Therefore some method to drop the placing concrete temperature may be effective to reduce the possibility of crack occurrence.

• Journal of the Korean Society of Costume
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• v.67 no.1
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• pp.1-21
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• 2017

The Korean folk drama is one of the traditional art performances of Korean folklore, and it is usually characterized by mask dances. An investigation on the costume of Korean folk drama is of great historical significance because they present the variety of typical costume according to the characters. The Sandae-Nori drama of Seoul Gyeong-gi province which was designated as im- portant culture property, has the closest form to general Korean folk costume. The usual characters have their typical costume and reflect the costume of the latter Choson Dynasty period. The costumes are used as a tool of the drama to indicate the character, and the impression of the dance. The costume of the Korean folk drama is made to indicate the character because it is for the play. What is more, the costume of the Sandae-Nori drama of Seoul Gyeong-gi province shows the general aspect of folk costume of the world, which remains as the symbol of the traditional culture and shows more decoration and visibility.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.597-600
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• 2003

Bi-2223/Ag HTS wires have been fabricated by the PIT(powder in tube)process. Intermediate annealing was carried out to increase the homogenization and uniformity of the superconducting filaments embedded in the silver matrix during the deformation process that is important to sustain the engineering critical current density in long superconducting wire. Intermediate annealing act to release the deformation hardening of the superconducting wires during drawing process. Rolling parameters were investigated to roll the superconducting tapes with uniform thickness, width and winding tensions. Critical current of 60 m long superconducting tapes was measured 54.3 A continuously after final sintering heat treatment. The phase analysis of Bi-2223/Ag superconducting tapes are examined by the XRD.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.251-254
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• 2005

소프트웨어 품질의 중요성이 커짐에 따라, 기업들은 품질을 높이기 위해 테스트에 많은 노력을 기울이고 있다. 최근에는 테스트 성과를 높이기 위한 방법중의 하나로 테스트 프로세스 개선이 주목 받고 있다. 이를 위해 기업들은 SW-CMM(Capability Maturity Model for Software), CMMI(Capability Maturity Model Integration)와 같은 일반적인 프로세스 개선 모델들이나, TMM (Test Maturity Model), TPI (Test Process Improvement Model), TCMM (Testing Capability Maturity Model)과 같은 테스트 프로세스 개선 모델들을 적용하고 있다. 그러나 일반적인 프로세스 개선 모델들은 테스트 관련 이슈를 충분히 다루고 있지 않고, 테스트 프로세스 개선 모델들은 구조가 불완전하거나 내용이 충분하지 않아 적용 시 많은 어려움이 있다. 이에 본 논문에서는 TMM 과 CMMI 를 기반으로 조직들의 테스트 프로세스 확립이나 개선을 지원할 수 있는 새로운 테스트 프로세스 성숙도 모델인 TPMM(Test Process Maturity Model)을 연구, 개발하였다. 개발된 TPMM 을 통해 조직에서 테스트 프로세스를 개선하고, 심사하는 것을 지원할 수 있을 것으로 기대된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.161-162
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• 2005

2G HTS coated conductor wire consists of textured substrate, buffer layer, superconduct layer, Ag cap layer, stabilizer. For practical application filed, coated conductor have mechanical and electrical stability and environment protection properties. This property Cu and stainless steel strip is laminated to Ag cap layer as stabilizer materials. Lamination process join stabilizer material strip and Ag cap layer with soldering method. we have laminated HTS with continuous dipping soldering process different stabilizer Cu and stainless steel strip and changed lamination process condition. The effect of lamination stabilizer and process condition has been investigated mechanical and electrical properties.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.48-53
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• 2003

This paper deals with the control of a horizontally placed flexible rotor levitated by electromagnets in a multi-input/multi-output (MIMO) active magnetic bearing(AMB) system. AMB is a kind of novel high performance bearing which can suspend the rotor by magnetic force. Its contact-free manner between the rotor and stator results in it being able to operate under much higher speed than conventional rolling bearings with relatively low power losses, as well as being environmental-friendly technology for AMB system having no wear and no lubrication requirements. In this MIMO AMB system, the rotor is a complex mechanical system, it not only has rigid body characteristics such as translational and slope motion but also bends as a flexible body. Reduced order nominal model is computed by consideration of the first 3 mode shapes of rotor dynamics. Then, the $H_{\infty}$ control strategy is applied to get robust controller. Such robustness of the control system as the ability of disturbance rejection and modeling error is guaranteed by using $H_{\infty}$ control strategy. Simulation results show the validation of the designed control system and the modeling method to the rotor.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.257-264
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• 2011

Recycling of industrial products as the stabilizers can be proper handling of industrial products and has positive side in terms of recycling of wastes. In this study, the final aims were to evaluate the usability as stabilizer of Bio-solids which was generated from contaminated soil with heavy metals after primary process and to compare the treatment efficiency with slag being currently applied in many existing sites. Soluble and exchangeable forms have closely related to pollution of groundwater and plant growth and they can be used to determine the effect of the stabilization efficiency. Slag and Bio-solids were tested to investigate the capacity of stabilizing arsenic. Slag treatment process 4 (PS-ball 5%) showed higher leachate concentration rather to 0.84% compared to treatment 1 (blank) based on an average of 0.63%. The other hand treatment 4 (Bio-solids 5%) showed the lowest soluble and exchangeable forms to 0.57% when Bio-solids was applied to stabilize arsenic. Thus, the leaching of arsenic will be more reduced if the Bio-solids are used as stabilizer in stead of slag which is being currently used in many fields.

• Korean Journal of Veterinary Service
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• v.21 no.4
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• pp.379-383
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• 1998

This survey was carried out to determine 5 residual sulfonamides(sulfamerazine : SMR, sulfamethazine : SMT, sulfamonomethoxine : SMM:, sulfadimethoxine : SDM, sulfaquinoxaline : SQX) in muscle of mouse. For this investigation, pertaining detection wavelength, residual levels and residual times in muscle of mouse were summarized as follows ; 1. Pertaining detection wavelength of 5 residual sulfonamides(SMR, SMT, SMM, SDM, SQX) was 270nm by HPLC/UV detection. 2. After 1 day put a stop to sulfonamides administration, residual levels was 1∼l.5ppm, but were not detected at day 7 3. Withdrawal time of 5 sulfonamides were about 7 days suspectly.