• 전기학회논문지P
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• 제63권3호
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• pp.183-188
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• 2014

Power conversion systems used in large gas turbine power plant can be divided into two main part. Because of the initial start-up characteristic of the gas turbine combustor, the gas turbine must be accelerated by starting device(LCI : Load Commutated Inverter) up to 10%~20% of rated speed to ignite it. In addition, the ECS(Excitation Control system) is used to control the rotor field current and reactive power in grid-connected synchronous generator. These two large power conversion systems are located in the same space(container) because of coordination control. Recently, many manufactures develop high speed controller based on function block available in the LCI and ECS with the newest power semiconductor. We also developed high speed controller based on function block to be using these two system and it meets the international standard IEC61131 as using real-time OS(VxWorks) and ISaGRAF. In order to install easily these systems at power plant, main controller, special module and IO module are used with high speed communication line other than electric wire line. Before initial product is installed on the site, prototype is produced and tests are conducted for it. The performance results of Integrated controller and application program(SFC, ECS) were described in this paper. The test results will be considered as the important resources for the application in future.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.139-144
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• 2008

본 논문은 건물의 형태와 동적특성을 변화시키지 않고 건물에 부가질량을 설치하여 건물의 진동을 제어하는 방법중 수동형 제진장치인 TLD(tuned liquid damper)와 MTLD(multiple tuned liquid damper)의 진동응답을 감소시키기 위해 진동대를 이용한 성능실험을 실시하였다. 따라서 기존의 형태별(원형, 직사각형) TLD 실험의 실험 데이터를 가지고 가진 진폭(1mm, 3mm, 5mm, 10mm, 20mm) 의 변화에 따른 고유진동수(0.44Hz, 0.55Hz)에 대한 MTLD의 형태별 실험을 통하여 TLD와 MTLD의 진동감소효과에 대한 성능실험을 비교 분석 하였다.

• 전기학회논문지
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• 제57권7호
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• pp.1175-1180
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• 2008

Recently agriculture has been intelligenced and automatized because the number of agricultural population is reduced, and the various agricultural machine is developed and utilized actively, In these agricultural automation system, the solenoid valve is widely used for the supply of water and fertilizer to the plant and soil. In this solenoid valve system, AC excitation solenoid valve is widely used because of economic merit and simple system scheme. However, the instantaneous chattering vibration and noise of plunger caused by the alternative MMF variation is very important performance characteristics. In order to reduce vibration the DC excitation solenoid valve is sometimes applied for the high-end applications. In this case, the control circuit is essential to control DC excitation current. It may causes the cost increase and system complexity and it is not suitable for the outdoor agricultural machine. In this paper, the electromagnetic structural improvement of AC solenoid valve is studied to reduce the dynamic vibration and noise. As an economical solution, the shading coil is additionally implemented to the conventional solenoid valve. As a result of this study, the vibration and acoustic noise is largely reduced by the compensating MMF of shading coil and it is verified by the test of prototype.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.178-183
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• 2020

A series of experiments covering lowest three natural frequencies of rolling coupled pitching were conducted to investigate liquid sloshing with low liquid depth. The test results show that the most violent liquid sloshing in rolling and pitching is located in the vicinity of the first order natural frequency (f1). When the excitation frequency of rolling and pitching is located between 0.98f1 and 1.113f1, roof-bursting phenomenon of liquid appeared, and the maximum impact pressure is at 1.09f1. When the external excitation frequency is at 1.113f1, the number of sloshing shocks decreases sharply. Furthermore, the space distribution of the impact pressure on the left bulkhead and the top bulkhead was analyzed. It is concluded that with low liquid filling, the impact load is greater near the free surface and the top of tank, and the impact position of the side bulkhead increases with the increasing of the frequency near the resonant frequency.

• Structural Monitoring and Maintenance
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• 제9권2호
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• pp.107-127
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• 2022

Structural health monitoring (SHM) has been related to damage identification with either operational loads or other environmental loading playing a significant complimentary role in terms of structural safety. In this study, a non-parametric method of time frequency analysis on the measurement is used to address the time-frequency representation for modal parameter estimation and system damage identification of structure. The method employs the wavelet decomposition of dynamic data by using the modified complex Morlet wavelet with variable central frequency (MCMW+VCF). Through detail discussion on the selection of model parameter in wavelet analysis, the method is applied to study the dynamic response of both steel structure and reinforced concrete frame under white noise excitation as well as earthquake excitation from shaking table test. Application of the method to building earthquake response measurement is also examined. It is shown that by using the spectrogram generated from MCMW+VCF method, with suitable selected model parameter, one can clearly identify the time-varying modal frequency of the reinforced concrete structure under earthquake excitation. Discussions on the advantages and disadvantages of the method through field experiments are also presented.

• Journal of Mechanical Science and Technology
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• 제15권3호
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• pp.291-299
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• 2001

Recently, severe wear on the shutdown rod cladding of Ulchin Nuclear Power Plant #1, #2 were observed by the Eddy Current Test(E.C.T.). In particular, the wear at the sixth card location was up to 75%. The test results indicated that the Flow Induced Vibration(F.I.V.) might be the cause of the fretting wear resulting from the contact between Rod Cluster Control Assemblies(RCCAs) and their spacing cards(guide plates) arranged in the guide tube. From reviewing RCCAs fretting wear repots and analyzing the general characteristics of F.I.V. mechanism in the reactor, geometric layout and flow conditions around the control rod, it is concluded that the turbulence excitation is the most probable vibration mechanism of RCCA. To identify the governing mechanism of RCCA vibration, an experiment was performed for a representative rod position in which the most serious fretting wear experienced among the six rod positions. The experimental rig was designed and set up to satisfy the governing nondimensional numbers which are Reynolds number and mass damping parameter. The vibration amplitude measurement by the non-contact laser displacement sensor showed good agreements in the frequency and the maximum wearing(vibration) location with Ulchin E.C.T. results and Framatome report, respectively. The sudden increase in the vibration amplitude was sensed around the 6th guide plate with mass flow rate variation. Comparing the similitude rod behaviour with the idealized response of a cylinder in flow induced vibration, it was found that he dominant mechanism of vibration was transferred from turbulence excitation to periodic shedding at the mass flow ate 90ι/min. Also the critical velocity of the vibration in RCCAs was determined and the vibration can be prevented by reducing the bypass flow rate below the critical velocity.

• 한국지진공학회논문집
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• 제7권4호
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• pp.71-79
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• 2003

사장교에서 케이블은 교량 전체에 있어서 매우 중요한 요소이다. 차량, 바람 혹은 풍우에 의한 케이블의 진동은 교량의 안전성과 사용성을 감소시키는 주요 원인이 되어왔으며 이러한 문제를 해결하는 효과적인 방법중의 하나는 케이블 댐퍼를 설치하는 것이다. 이 케이블 댐퍼를 최적으로 설계하기 위해서는 케이블의 동특성을 정확하게 평가해야 하며 케이블 동특성치를 얻기 위해서는 정확한 가진이 필요하다. 따라서 본 연구에서는 케이블 가진시스템을 개발하고 성능을 평가하기 위해 케이블 가진시스템의 운동방정식을 유도하였으며, 케이블 가진기를 케이블 모형에 설치하여 정현진동실험과 공진진동실험을 수행하여 케이블의 동특성을 효과적으로 구하였다.

• 전기전자학회논문지
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• 제23권2호
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• pp.586-593
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• 2019

본 논문은 초미세먼지 증가를 억제하고자 1972년 건설된 국내무연탄과 유류를 혼소하는 발전설비를 2017년 국내최초, 최대 용량의 신재생 발전 연료 중 하나인 순수 목재를 가공한 친환경 고형연료인 바이오매스[우드팰릿] 발전방식으로 변경하였다. 발전기 제어계 중요 설비 교체에 따른 산업부 고시 "전력계통 신뢰도 및 전기품질 유지기준" 제 32조 발전설비 신/증설 시 발전설비 특성자료를 제출에 의거 발전기 기술특성시험을 실시하였으며, 시험을 통하여 발전기/제어계 모델정수 도출 및 검증을 수행하였다. 발전기 연료변경에도 해당 발전기 설비의 성능 및 여자시스템의 전압제어특성이 양호함을 재확인하였다. 차후 화석연료를 신재생 연료로 교체하고자 하는 발전소에서 참고하는데 기여할 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1037-1038
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• 2013

• 한국인쇄학회지
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• 제6권1호
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• pp.13-39
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• 1988

Test colors are halftone dot printed at the rate of 10% halftone dot area by process inksblack, cyan, magenta and yellow ink. Reproduced colors are measured by the weighted-ordinate colorimetric method and the direct colorimetric method. The weighted-ordinate colorimetric method compare favorably with the direct colorimetric method, because the former has good regular changes of tristimuIus values, chromacity coordinates, excitation purities, value functions and has smaller errors of dominant and complementary wavelengths than the latter. All test colors classify with the Munsell renotation.tation.