• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1654-1655
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• 2007

본 논문은 시간 변동 시간 지연을 가지는 불확실한 선형 뉴트럴 시스템에 관한 관측기 설계에 대해서 논의한다. Lyapunov-Krasovskii의 이론을 이용하여 불확실한 시간 지연을 가지는 시스템의 안정도를 판별한다. 뉴트럴 시스템의 안정도 조건을 시간 변동 시간 지연에 종속적인 충분조건으로 제시한다. 선형 행렬 부등식을 이용하여 안정도 조건을 제시하고, 선형 행렬 부등식의 해를 이용하여 관측기의 이득값을 설계한다. 설계된 관측기의 이득값을 포함한 오차 상태 방정식의 안정도를 판별한다. 예제를 통하여 논문의 결과를 입증하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.231-238
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• 2010

Combustion stability rating tests under condition low pressure of a 75-$ton_f$ liquid rocket engine(LRE) thrust chamber were carried out. Mixing head with decreased number of injectors than that of the other but with the same mass flow rate to the combustion chamber showed self-oscillation instability in chamber pressure of 30 bar. The other combustion chamber with increased number of injectors showed that high frequency combustion stability was maintained under condition of same pressure, but self-oscillation instability was generated in chamber pressure of 20 bar which can be considered as stability boundary region of this mixing head.

• Journal of Venture Innovation
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• v.3 no.1
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• pp.67-85
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• 2020

In this article, we investigated the overall relationship between the employment stability of senior wage earners and their quality of life. Moreover, we analyzed a mediated effect of satisfaction variables: income satisfaction, work environment satisfaction, and overall job satisfaction. For the research, we used the data from the Korean Longitudinal Study of Aging (KLoSA) and analyzed the data set of 1,318 senior wage earners. The result showed that there exists a positive relationship between job stability and job satisfaction, while the overall quality of life has a negative relation with both the job stability and job satisfaction. This study showed a contradictory result from previous studies that claim that the quality of employment such as job stability and job satisfaction has a positive relationship with the quality of life, and the result implies that the research on senior wage earners requires perspectives different from those on other age groups and social classes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.8-15
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• 2018

An experiment was carried out to evaluate the lateral torsional stability of a girder with respect to the location and magnitude of prestressing force. The test of evaluating the lateral displacement and stability of a girder could cause an unexpected result due to various parameters, such as material nonlinearity, initial geometric imperfections, prestressing force, and loading and support conditions. Therefore, a small model testing was programmed to control the various parameters and assess the lateral torsional stability with respect to the prestressing force. This study proposed and fabricated an experimental apparatus that can satisfy the loading and in-plane and out-of-plane support conditions and also contol the prestressing force. The result of the experiment showed that the lateral torsional stability increased when the prestressing force was applied in the bottom flange of the girder. As a result, this study proposed an analytical equation that can account for the effect of the prestressing force in the lateral torsional stability of a girder.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.577-587
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• 2007

The length of study area was about 450m, and it was shown the geological condition of distinguished change of rock by cutting slope. In order to establish a slope stability, we carried out an engineering geological investigations about rock constituent, rock structure and a direction of discontinuous plane. The study area was divided into six section considered by direction of cutting slope, height of slope and geological condition. Analysis of cutting slope stability was carried out with stereo-graphic projection method by DIPS program which was feasible of stability analysis with geometrical correlation for a direction of discontinuous plane and direction of cutting slope. From analysis of cutting slope stability considered by construction, stability and economical efficiency, the slope stability countermeasures such as a high tensile wire net, slope protection method and enhanced retaining wall were established and operated which minimized effect caused by lower end of road on a relaxation of huge rock.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.364-367
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• 2000

토양속의 인산 가용화를 위한 Pantoea agglomerans 배양의 최적조건과 균주 고정화를 위한 안정성을 조사한 결과 $30^{\circ}C$, pH 7.0, 공기유량 2vvm에서 각각의 흡광도 값이 51시간에서1.756과 1,713, 50시간대에 1.819로써 가장 균의 성장이 활발한 것으로 나타났으며, 1% $CaCl_2$ 용액에서 172시간대에 흡광도값 2.361로 가장 안정하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.79.2-79.2
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• 2011

플라이 휠 에너지 저장장치(Flywheel Energy Storage System: FESS)는 전기 에너지를 회전 운동 에너지로 저장하였다가 필요시 회전 운동에너지를 전기 에너지로 변환하여 재사용 가능한 에너지 저장장치 이다. 최근 전력 변환 기술의 발전으로 인하여 플라이휠 에너지 저장 장치의 에너지 입출력 속도가 빨라지고 대용량의 에너지를 저장할 수 있게 되었다. 본 논문에서는 이러한 플라이휠 에너지 저장 장치의 전력 입출력 특성을 이용하여 전력 시스템에서 발생하는 저주파 진동(Low frequency oscillation)을 억제하는 방안을 제시 하여 안정도를 향상 시키고자 하였다. 전력 시스템은 발전조건, 전송조건, 부하조건에 따라 동작 조건이 지속적으로 변하고 있다. 이러한 동작 환경 변화는 전력 시스템에 대한 수학적인 표현과 실제 전력계통간의 차이가 발생하기 때문에 정확한 제어 목적을 달성하기가 힘들다. 따라서 본 논문에서는 제어기 설계 단계에서 전력 계통의 불확실성을 고려할 수 있는 $H_{\infty}$ 제어 기법을 이용하여 플라이휠 에너지 저장장치를 위한 강인 제어기를 설계 하였다. 제안한 플라이휠 에너지 저장장치의 강인 제어기의 유용성을 입증하기 위하여 1기 무한대 모선에 적용한 결과를 비선형 시뮬레이션을 통하여 다양한 외란이 발생한 경우에 외란 억제 성능과 강인성에 대하여 고찰 하였으며, 제안한 방식이 기존의 전력계통 안정화 장치(Power system stabilizer: PSS) 보다 효율적이며 전력계통의 안정도 향상에 크게 기여함을 보이고자 하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.4
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• pp.15-20
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• 1982

Stabilization by decentralized control is an important problem in large scale systems and there has been an increasing interest in this area. The objective of this paper is to obtain the sufficient condition for an interconnected system to be stabilited by local feedback. Recently there has been many papers about this, and we further broaden the class of interconnections for which we can find a decentralized control to stabilize the overall system. The interconnection matrix may take any arbitrary time invariant values and this implies connective stability in some sense. The assumed model is mire general than most of previous ones, and as a special case, when each subsystem is given by companion form of a single inputs the result is compared with that of Ikeda and Siljak. The obtained result is illustrated by examples.

• The Journal of Engineering Geology
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• v.31 no.2
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• pp.199-209
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• 2021

This paper is written to evaluate the ground stability according to the construction of Jeju 2nd airport. Sumgol is the unique characteristics of Jeju soil, which is used to evaluate the ground stability of the airport. The research contents are as follows. 1) The geotechnical characteristics for Jeju 2nd airport was analyzed, and the Sumgol and geotechnical properties were calculated based on the existing geotechnical survey data. 2) The divided sections of Jeju 2nd airport were modeled to evaluate the ground stability after determining the section (runway and airport facilities) which have the different soil and loading properties. 3) The stability and deformation ranges of the airport ground were identified through numerical analysis. The entire airport was divided into three sections to analyze the stability of Jeju 2nd airport, and calculated the stresses, settlements, and strains of each section by computer numerical analysis modeling. For modeling, the ground and load conditions were examined, also pavement conditions for each airport ground section were examined. From the analysis results of each section according to the ground conditions, the vertical settlements were analyzed as 0.11~0.18 m and the sum of effective stress and pore water pressure were 92.75~445 kPa. These results were made by taking into account the Sumgol of the bottom ground without reinforcement, also the soil strength parameters of the airport ground were reduced for computer modeling, Therefore, if proper reinforcements are applied to the ground of Jeju 2nd airport, sufficient airport ground stability can be secured.

• Electric Engineers Magazine
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• v.229 no.9
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• pp.27-36
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• 2001

기존의 HID 램프용 안정기는 대부분이 인덕터와 콘덴서를 사용한 수동소자 회로이며 사용 전원 60HZ에서는 그 부피가 커짐은 물론 중량이 무거워 설치에 제약조건이 많고 효율이 나쁘기 때문에 전자식 안정기를 사용하여 단점을 보완할 필요가 있다.