• 대한전기학회논문지:시스템및제어부문D
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• 제54권6호
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• pp.372-375
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• 2005

The tracking performance of optical disk drive(ODD) system can be improved using disturbance observer(DOB). But, DOB was not easily applied in the ODD system because the additional microprocessor was needed. In this paper, we propose an error-based modified disturbance observer(EM-DOB) for ODD system. Due to the simplified structure of EM-DOB, the system is easily implemented to the digital control algorithm or the analog circuit. In these algorithms, disturbances rejection performance of system can be tuned as Q filter parameters are selected. Based on analysis of sensitivity function, three guidelines of Q filter design are suggested. Experimental results of DOB and EM-DOB are evaluated under the forced disturbances.

• 수산해양기술연구
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• 제58권3호
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• pp.241-250
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• 2022

This paper describes the design of H-infinity controller for robust control of a DC motor system. The suggested controller can ensure robustness against disturbance and model uncertainty by minimizing H-infinity norm of the transfer function from exogenous input to performance output and applying the small gain theorem. In particular, the controller was designed to reduce the effects of disturbance and model uncertainty simultaneously by formalizing these problems as a mixed sensitivity problem. The validity of the proposed controller was demonstrated by computer simulations and real experiments. Moreover, the effectiveness of the proposed controller was confirmed by comparing its performance with PI controller, which was tested under the same experimental condition as the H-infinity controller.

• 전자공학회논문지
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• 제50권6호
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• pp.91-98
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• 2013

생체자기신호 측정을 위해 고인덕턴스 코일과 계측 증폭기를 내장한 자기센서칩을 $0.18{\mu}m$ CMOS공정으로 제작하였다. 생체자기신호를 측정하기 적합한 감도와 대역폭을 가지는 고인덕턴스 코일센서를 전자기장 시뮬레이션 프로그램으로 설계하였으며, 온칩에 구현하기 위해 트렌스컨덕턴스 감쇄방법 적용한 low gm OTA를 구현하였다. 자기센서칩의 출력신호 감도는 $3.25fT/{\mu}V$이며, output reference noise는 21.1fT/${\surd}$Hz이다. 계측 증폭기부분은 current feedback 기반으로 설계되었으며, 자기 신호 잡음을 줄이기 위해서 0.5~5kHz의 대역의 BPF를 설계하였다. MPW칩 테스트에서 common mode rejection ratio(CMRR)는 117.5dB로 측정하였으며, input reference noise가 $0.87{\mu}V$ 이하로 유지되도록 설계하였다.

• Membrane and Water Treatment
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• 제9권6호
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• pp.435-445
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• 2018

In this work, desalination experiments were performed on vacuum membrane distillation (VMD). Process parameters such as feed flow rate, vacuum degree on permeate side, feed bulk temperature and feed salt concentration were optimized using sensitivity analysis and Taguchi method. The optimum values of process parameters were found to be 2 lpm of feed flow rate, $60^{\circ}C$ of feed bulk temperature, 5.5 kPa of permeate-side pressure and 5000 ppm of salt concentration. The permeate flux at these conditions was obtained as $26.6kg/m^2{\cdot}hr$. The rejection of salt in permeate was found to be 99.7%. The percent contribution of various process parameters using ANOVA results indicated that the most important parameter is feed bulk temperature with its contribution of 95%. The ANOVA results indicate that the percent contribution of permeate pressure gets increased to 5.384% in the range of 2 to 7 kPa as compared to 0.045% in the range of 5.5 to 7 kPa.

• 한국생활과학회지
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• 제21권4호
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• pp.715-728
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• 2012

This research aims at examining the relationships between mother-toddler interaction and its related variables. A total of 49 toddlers and their mothers were participated and observed in the child lab during free play. The main results of this study are as follows. First, among the mother-toddler interaction, 'involvement' was frequently used in comparison with the 'rejection' was the hardly used in their interaction. Second, the mothers' sensitivity, parenting stress, and the mother-toddler interaction had no significant difference by the mothers' job status or gender of toddlers. However, their parenting stress was lower in working mothers or mothers who have girls. Third, mother-toddler interaction was significantly correlated with the mothers' sensitivity, parenting stress, parenting style, and the temperament of toddlers. On the basis of this results, the implication related to the variables influencing mother-toddler interaction was discussed.

• Journal of the Korean Data Analysis Society
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• 제20권6호
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• pp.3185-3199
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• 2018

본 연구에서는 운전장면 개별요소들에 대한 중년 및 고령운전자의 작업기억의 특성을 반응민감도, 반응편파 및 반응시간을 통해 비교하였다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 고령운전자 집단은 중년운전자 집단에 비해 민감도가 낮았고 특히 중년운전자 집단의 경우는 중심자극과 주변자극에 대한 민감도에서의 차이가 유의하지 않았던 반면, 고령운전자 집단의 경우는 중심자극에 비해 주변자극에 대한 민감도가 현저하게 더 낮았다. 둘째, 중년운전자 집단은 전반적으로 보수적으로 반응한 반면 고령운전자 집단은 대체적으로 관대한 방향으로 반응하는 경향이 상대적으로 더 컸다. 셋째, 중년운전자들에 비해 고령운전자들의 반응시간이 더 느렸고, 중심자극보다는 주변자극에 대한 반응시간이 더 느렸으며, 반응의 유형에 따라서는 적중의 반응시간이 가장 빨랐던 반면 헛경보의 반응시간이 가장 느렸다. 특히, 탈루과 정기각 반응에 대해서는 두 집단 사이의 반응시간 차이가 더 증가하였다. 이러한 결과는 중년운전자들에 비해 고령운전자들은 운전장면 개별요소에 대한 작업기억에서의 파지가 상대적으로 더 불완전하고, 이에 따라 작업기억에 기초한 신속한 판단에서 어려움이 증가할 수 있음을 시사한다.

• 아동학회지
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• 제16권1호
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• pp.113-131
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• 1995

The objectives of this study were to investigate (1) the relations between infant-mother attachment and maternal sensitivity, maltreatment, stress, and childhood experience, and (2) relations between infant-mother attachment and infant temperament. The subjects of the study were 55 14 to 20 month-old infants (27 boys and 28 girls) and their mothers in Seoul. In order to assess the patterns of infant-mother attachment, each infant-mother dyad was videotaped in the modified Ainsworth's Strange Situation. Each dyad was filmed for 3 minutes in the Questionnaire Situation of Smith and Pederson(Smith, & Pederson, 1988) to assess maternal sensitivity responding to infant's cues. Each mother also was interviewed by using a semi-structured questionnaire made by author to measure maternal maltreatment. Each mother was asked to complete three Likert-type questionnaires, containing Parenting Stress Index (PSI) (Abidin, 1990) to measure the maternal stress, Mother-Father Peer Scale (MFPS) (Epstein, 1983) to measure childhood experience, and Emotionality, Activity, Sociality (EAS) (Buss, & Plomin, 1984) to measure infant's temperament. The statistical procedures used for data analyses were correlation, one-way ANOVA, multiple regression, and Cronbach's ${\alpha}$ coefficient. The results showed that (1) mothers of insecure-avoidant infants maltreated their infants more than mothers of secure infants, and (2) in the multiple regression analysis, maternal maltreatment was predicted by maternal education, maternal stress (parent domain), and maternal childhood experience in relation to her own mother (acceptance vs. rejection).

• 한국소음진동공학회논문집
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• 제15권10호
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• pp.1148-1159
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• 2005

In this paper, the various uncertainties generated in an optical disk drive (ODD) and the robust servo designs considering the uncertainties are studied. First, the brief introduction an ODD and the servo error tolerance of it are discussed. Then, the classifications of uncertainty and the concept of relative stability are introduced. Considering the uncertainty of an ODD, two robust control approaches are applied: (i) mixed sensitivity approach in H$\infty$ control theory for unstructured uncertainty, (ii) QFT for structured uncertainty Finally, the designed controllers are realized by DSP, and these controllers are applied to a commercial DVD-ROM drive. From these experiments, we prove that the designed robust controllers have more good disturbance rejection performance and robustness when it is compared to the conventional lead-lag controller.

• 한국전산유체공학회지
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• 제11권3호
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• pp.8-13
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• 2006

The north panel of a geostationary satellite is used as one of the main radiators, on which communication equipment or bus equipment are installed. The thermal control of panel is designed by using embedded heat pipes and surface heat pipes (or external heat pipes) to spread out heat dissipated from equipment all over the radiator evenly and finally to reject the heat to the space through the radiator efficiently. This panel is also divided by several areas based on the operating temperature and dissipation of equipment in order to increase heat rejection capability of radiator. The thermal analysis is carried out for the hot case, Winter Solsitce EOL (End Of Life), in order to validate thermal design of the panel utilized 6 surface heat pipes and 8 embedded heat pipes. The sensitivity studies for the heat pipe failure case and no heat pipe case are performed and compared to its normal state. The heat transport capability of heat pipe is also obtained from these calculations.

• 비파괴검사학회지
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• 제26권6호
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• pp.380-389
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• 2006

A new laser-based ultrasonic receiver that is based on multi-channel interferometry is shown to be well suited for robust and sensitive detection of ultrasound in industrial environment. The proposed architecture combines random-quadrature detection with detector arrays and parallel multi-speckle processing. The high sensitivity is reached, thanks to the random phase distribution of laser speckle caused by surface roughness. High-density parallel signal processing is achieved by using a simple demodulation technique based on signal rectification. This simple detection scheme is also demonstrated for rejection of the laser intensity noise, making possible the use of lower cost laser without reduction in performances. Results demonstrating this new principle of operation and its performances are presented.