• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.670-677
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• 1991

All models of dynamical systems invariably have some measure of uncertainties associated with some of their dynamics. The recent approaches to establish robustness of stabilizing feedback control against the possible uncertainties have a serious limitation, that is, their applicability only to the systems that satisfy the matching conditions. Such conditions are rarely met in general applications. If a particular system satisfies the matching conditions, the addition of an actuator will destroy the satisfaction of such conditions. In this paper, we develop robust control algorithm for uncertain multivariable systems in which the matching conditions are not necessarily met. In order to eliminate an influence over partial state variables due to unknown constant disturbances we perform the appropriate block-decomposition for a given system. Functional observers are introduced to estimate the unknown constant disturbances. The sliding mode controller is designed in such a way that the partial state variables in the state-space are directed towards switching surfaces and regulated to the origin asymptotically. Numerical examples are discussed as illustrations.

• 전기학회논문지
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• 제64권6호
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• pp.912-921
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• 2015

In this paper, we introduce fuzzy inference-based real-time deterioration diagnosis system with the aid of infrared thermal imaging camera. In the proposed system, the infrared thermal imaging camera monitors diagnostic field in real time and then checks state of deterioration at the same time. Temperature and variation of temperature obtained from the infrared thermal imaging camera variation are used as input variables. In addition to perform more efficient diagnosis, fuzzy inference algorithm is applied to the proposed system, and fuzzy rule is defined by If-then form and is expressed as lookup-table. While triangular membership function is used to estimate fuzzy set of input variables, that of output variable has singleton membership function. At last, state of deterioration in the present is determined based on output obtained through defuzzification. Experimental data acquired from deterioration generator and electric machinery are used in order to evaluate performance of the proposed system. And simulator is realized in order to confirm real-time state of diagnostic field

• 대한간호학회지
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• 제14권2호
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• pp.47-54
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• 1984

In an attempt to take Comprehensive nursing care the author tested cognitive function and psychiatric disturbance produced by normal adults. Mini-mental state and simple reaction time were tested and general health questionnaire was conducted two hundred subjects. The data were analyzed statistically and the results follow: 1. The score of mini-mental state of the elderly group was less significant than that of the younger group in the tests of cognitive dysfunction. The score of MMS of the female group, the illiteracy group less significant than that of other groups in the test of cogntive dysfunction. 2. Reaction time of the elderly group was slower than that of the younger group. Reaction time of the female group was slower than that of the male group. Reaction time of the illiteracy group was the slowest & the unskilled group was slower than that of the other groups. 3. As a result of the results of psychiatric disturbance the score of general health questionnaire of the elderly group was significantly higher than that of the younger group in the tests of psychiatric disturbance. The test of psychiatric disturbance sho-wed that the score of general health questionnaire of the female group was significantly higher than that of the male group in the tests of psychiatric disturbance. The illiteracy group was the highest in the psychiatric disturbance among other groups and the unskilled group was significantly higher than the other groups. 4. Education had higher correlation to mini-men-tat state, while age negative correlation in comparison with other variables age had higher correlation to reaction time, while education had negative correlation in comparison with other variables. Sex had low correlation in these tests.

• Wind and Structures
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• 제27권3호
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• pp.149-161
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• 2018

A reliability analysis method is proposed in this paper based on the maximum entropy (MaxEnt) principle in which constraints are specified in terms of the fractional moments instead of integer moments. Then a multiplicative dimensional reduction method (M-DRM) is introduced to compute the fractional moments. The method is applicable for both explicit and implicit limit state functions of complex structures. After two examples illustrate the accuracy and efficiency of this method in comparison to the Monte Carlo simulation (MCS), the method is used to analyze the flutter reliability of suspension bridge. The results show that the empirical formula method in which the limit state function is explicitly represented as a function of variables is only a too conservative estimate for flutter reliability analysis but is not accurate adequately. So it is not suitable for reliability analysis of bridge flutter. The actual flutter reliability analysis should be conducted based on a finite element method in which limit state function is implicitly represented as a function of variables. The proposed M-DRM provide an alternate and efficient way to analyze a much more complicated flutter reliability of long span suspension bridge.

• 한국초지조사료학회지
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• 제32권4호
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• pp.361-368
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• 2012

The present study was conducted to develop persimmon peel, a by-product of dried persimmon manufacturing, as a feed additive via lactic acid bacteria fermentation. Pediococcus pentosaceus, Lactobacillus plantarum, and three strains of Leuconostoc mesenteroides were used as a starter culture in the solid state fermentation of persimmon peel, and antioxidant activity and total polyphenol content were assessed. Leuconostoc mesenteroides KCTC 3100 showed high antioxidant activity (p<0.05), whereas Pediococcus pentosaceus showed high total polyphenol content (p<0.05). These two strains were thus selected as starter culture strains. Glucose, sucrose and molasses were used as variables for optimization and a total 15 experimental runs were produced according to Box-Behnken design. Regarding significant effects of variables, molasses showed linear and square effects on antioxidant activity of persimmon peel fermentation (p<0.05). In conclusion, optimum concentrations of glucose, sucrose, and molasses were determined to be 4.2, 3.9 and 5.3 g/L, respectively, using a response surface model. Antioxidant activity was also improved 2.5 fold after optimization.

• 한국통신학회논문지
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• 제19권12호
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• pp.2353-2363
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• 1994

본 논문에서는 외란이 존재하는 로보트 시스템에 대하여, 축소차수관측기를 사용하여 강인한 디지털 제어기의 설계방법을 다루었다. 대부분의 로보트 매니퓰레이터 경우는 상태변수 모두를 측정할 수 없기 때문에 측정할 수 없는 상태변수들은 추정되거나 재구성되어야 한다. 또 다른 문제점들은 미분불가능한 쿨롱마찰력과 같은 비선형 성분, 중력에 의한 외란, 그리고 구동모터와 매니퓰레이터 사이에 존재하는 뒤틀림 스프링 효과이다. 제어기의 설계는 측정가능한 상태변수와 축소차수 관측기에 의하여 추정한 상태변수들을 궤환시키고 출력 쪽에 이산적분기를 첨가하여 구성하였다. 제어기의 궤환이득은 우선 최적제어이론에 의해 구하고, 만약 시스템 응답이 리미트싸이클을 가지면 혼성시스템에 대한 기술함수법을 적용해서 제어기의 이득을 재조정하여 리미트싸이클을 제거하였다.

• 한국정보과학회논문지:정보통신
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• 제30권3호
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• pp.416-423
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• 2003

본 논문에서는 버퍼를 공유하는 패킷 교환기의 연속 시간 큐잉 모델을 제시하고 큐 길이 확률 분포를 구하는 근사 계산 알고리즘을 제안한다. N 개의 입력 프로세스는 상호 이질적인 버스트 특성을 갖는다. 입력 프로세스는 계차-2 콕시안 분포로서 모형화하며 서버의 서비스 시간은 계차-r 얼랑 분포로서 모형화한다. 근사 알고리즘은 통합된 상태 변수를 사용하여 큐잉 시스템을 표현한다. 먼저 N개의 입력프로세스는 하나의 통합된 상태 변수로 나타내며 큐잉 시스템은 서브 시스템으로 분해하고 이것을 통합된 상태 변수로 나타낸다. 그리고 이러한 통합된 상태 변수를 사용하여 반복적인 방법에 의해서 상태 방정식의 해를 유도한다. 근사 알고리즘의 타당성은 시뮬레이션을 통해서 검증한다.

• 펄프종이기술
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• 제35권4호
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• pp.48-56
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• 2003

In this work an integrated model for paper plants combining wet-end and dry section is developed and a model predictive control scheme based on the plant model is proposed. Closed-loop process identification method is employed to produce a state-space model. Thick stock, filler flow, machine speed and steam pressure are selected as input variables and basis weight, ash content and moisture content are considered as output variables. The desired output trajectory is constructed in the form of 1st-order dynamics. Results of simulations for control of grade change operations are compared with plant operation data collected during the grade change operations under the same conditions as in simulations. From the comparison, we can see that the proposed model predictive control scheme reduces the grade change time and achieves stable steady-state.

• Structural Engineering and Mechanics
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• 제59권5호
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• pp.853-866
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• 2016

This paper examines a methodology for computing the probability of structural failure of reinforced concrete beams subjected to fire. The significant load variables considered are dead load, sustained live load and fire temperature. Resistance is expressed in terms of moment capacity with random variables taken as yield strength of steel, concrete class (or grade of concrete), beam width and depth. The flexural capacity is determined based on the design equations recommended in Indian standard IS456:2000. Simplified method named $500^{\circ}C$ isotherm method detailed in Eurocode 2 is incorporated for fire design. A transient thermal analysis is conducted using finite element software ANSYS$^{(R)}$ Release15. Reliability is evaluated from the initial state to 4h of fire exposure based on the first order reliability method (FORM). A procedure is coded in MATLAB for finding the reliability index. This procedure is validated with available literature. The effect of various parameters like effective cover, yield strength of steel, grade of concrete, distribution of reinforcement bars and aggregate type on reliability indices are studied. Parameters like effective cover of concrete, yield strength of steel has a significant effect on reliability of beams. Different failure modes like limit state of flexure and limit state of shear are checked.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.625-633
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• 2021

This study analyzes the impact of the reward variable on employees' performance through work motivation and employee engagement. This study's specific purpose is to investigate employee engagement's mediating role in the relationship between reward and employee performance. The sample of research is the employee at Sukorejo, Pasuruan Indonesia. The sample is permanent employees at manufacture corporate. The sample size is 150 employees of the total 759 workers through the calculation of the Slovin formula. Respondents in this study were employees with the criteria for having worked for at least last five years. The data obtained is in the form of answers from employees to the statements submitted. The data analysis was used structural equation modeling partial least square. To test the relationship between variables, it was equipped with a Sobel mediation test of statistics. SmartPLS 3.0 is used to help analyze the relationship between variables. The result shows that the reward does not have a direct influence on the performance of employees. However, it has a significant positive effect on the performance of employees through employee engagement. While working motivation variable does not have the role as a mediation variable related to the effect of reward on employee performance.