• Journal of The Korean Association For Science Education
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• v.26 no.2
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• pp.222-231
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• 2006

The purposes of this study were to survey internal engagement in science fair and explore the causal relationship between internal engagement and motivation for participation. A written questionnaire on queries into motivation for participation and internal engagement were developed and tested. The subjects were 1066 students from 4th to 9th grade who had participated in the Youth Science Contest under the auspices of the Korea Science Foundation. Interest and commitment were selected as constructing factors of internal engagement. Through exploratory factor analysis, preference, reward, and social motivation were determined to be the factors affecting the motivation to participate. Boys showed higher internal engagement than girls, and interest and commitment were found to be higher in elementary school students(p<0.01). There was no difference in interest among elementary school students; however, fourth grade students showed lower commitment than other students(p<0.01). Ninth grade students showed the lowest interest and commitment among junior high school students(p<0.01). To explore the causal relationship between internal engagement and factors influence internal engagement, path analysis was used. The selected model illustrated how reward motivation affected commitment directly, and how preference motivation affected interest directly but only commitment indirectly through interest. Reward motivation affected commitment with a standardized direct effect coefficient of 0.17. Preference motivation affected interest with a standardized direct effect coefficient of 0.75 and commitment with a standardized total effect coefficient of 0.63(direct effect; 0.27 and indirect effect; 0.36). In addition, interest affected commitment with a standardized direct effect coefficient of 0.49. Social motivation did not affect interest and commitment and reward motivation did not affect interest.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.98-106
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• 2001

This paper presents external load disturbance compensation that used to deadbeat load torque observer and regulation of the compensation gain by parameter estimator. As a result, the response of PMSM follows that of the nominal plant. The load torque compensation method is compose of a dead beat observer that is well-known method. However it has disadvantage such as a noise amplification effect. To reduce of the effect, the post-filter, which is implemented by MA process, is proposed. The parameter compensator with RLSM(recursive least square method) parameter estimator is suggested to increase the performance of the load torque observer and main controller. Although RLSM estimator is one of the most effective methods for online parameter identification, it is difficult to obtain unbiased result in this application. It is caused by disturbed dynamic model with external torque. The proposed RLSM estimator is combined with a high performance torque observer to resolve the problems. As a result, the proposed control system becomes a robust and precise system against the load torque and the parameter variation. A stability and usefulness, through the verified computer simulation and experiment, are shown in this paper.

• Journal of Chest Surgery
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• v.41 no.1
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• pp.89-94
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• 2008

Background: Thoracoscopic R3 sympathicotomy can effectively treat palmar hyperhidrosis. Here, we evaluated post-operative outcomes of patients receiving a thoracoscopic R3 sympathicotomy due to palmar hyperhidrosis. Material and Method: From January 2001 to December 2006, 225 patients were treated with a R3 sympathicotomy, and follow up was completed for 200 patients, with an average follow up period of 51.7 ($11{\sim}80$) months. We measured postoperative hand sweating according to four grades; dry (grade 1), proper (grade 2), light sweating (grade 3), heavy sweating (grade 4) and evaluated patient satisfaction using 4 grades: very good (grade 0), good (grade1), regular (grade 2), and deficient (grade 3). Result: There were no differences in clinical parameters between the compensatory sweating group and the non-compensatory sweating group. There was a 83.5% compensatory sweating rate. The degree of compensatory sweating related to the patient's body mass index and was influenced by the season, environmental temperature, and emotional stress. Conclusion: The satisfaction rate was 61.5%, and the degree of satisfaction related to the development of compensatory sweating. Therefore, reducing compensatory sweating would increase patient satisfaction with R3 sympathicotomies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.413-423
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• 2003

The CMA algorithmis most widely investigated blind algorithm and the most widely used one in practice. But, since nonlinear CM cost function have not closed form solution about the optimum weight. There have been difficultiesto analyze the CMA equalizer's theoretical performance. Recently, Zeng presents the notable theoretical resultabout the MSE of CM-minimizing estimators for the FIR linear channel in the presence of AWGN. Through this method, It wouldbe possible to campare the theoretical performance between CMA and Wiener equalizer in terms of MSE. In this paper, based on Zeng's method, we first calculate the theoretical MSE bound of CMA equalizer in partial response channel which is widely used in HDD, digital VCR such as high-density digital recording.playback systems. We confirmedthis result withthe computer simulation. Except this, we also performedthe theoretical and simulation analysis about the modified CMA equalizer, which was proposed to improve the performance of CMA equalizer in partial response channel. Finally, we compare and evaluate the performance analysis results between CMA and Modified CMA equalizer.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.41-42
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• 2001

본 연구에서는 빠른 응답특성과 넓은 시야 각 특성을 갖는 Optically Compensated Bend Mode Liquid Crystal Displays(OCB LCDs)의 전기광학 특성을 계산하였다. 액정의 운동방정식을 시뮬레이션하여 얻은 분자배열 분포로부터 광학적 투과 특성을 계산하였으며, 누설광 차단과 수평 및 수직 방향의 넓은 시야각을 확보하기 위하여 보상필름으로써 Wide View Film을 적용하였다. 이러한 결과를 이축성 필름을 사용한 기존의 OCB LCDs와 비교함으로써 Wide View Film을 적용한 OCB LCDs의 시야의존 특성이 향상됨을 확인하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.1
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• pp.12-17
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• 1975

This paper describes a new simplified logarithmic counting Tatemeter for the measurement of wide range counting rates without selector switch. Theoritical analysis of the proposed circuit and synthesis technique for designing a multi.decade instrument using this configuration are given. It has a linear response on the logarithmic scale for random pulses of Poisson's distribution as well as for periodic pulses. The experimental circuit designed by the proposed technique has a good logarithmic response over 5 decades covering the counting rates from 1 pps to $10^5$ pps. Also the causes of inaccuracy in the low and high range are examined and effestively removed.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.247-257
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• 2006

This paper shows the comparison of operating characteristics between squirrel cage induction generator and DFIG(Double Fed Induction Generator). Because squirrel cage induction generator consume the reactive power due to magnetizing reactance, the capacitor is need to compensate the reactive power. Otherwise, two back-to-back PWM voltage-fed inverters connected between the stator and the rotor allow sub/super synchronous operation with low distortion currents. In this paper, the response characteristics of squirrel cage induction generator and DFIG, were analyzed and investigated using PSCAD/EMTDC.

• Journal of Power System Engineering
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• v.4 no.2
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• pp.58-64
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• 2000

A method for the position control of a pneumatic cylinder using a linearized controller is proposed. Pneumatic cylinder has highly nonlinear characteristics and modelling of the system has been difficult. Compliance of the pneumatic cylinder is materially changed according to the operating position. So, in the case that fixed gain controller obtained by a linearized model at a specified position is used, response of the cylinder should be changed according to the operating position. In order to get a designed results regardless of operating positions, a controller for compensation of the nonlinear characteristic with a linearlization compensator is designed and simulation results show that this method is appropriate for the control object.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.3
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• pp.289-296
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• 2002

New discrete-time modeling and simulation techniques are proposed which take advantages of the special features of PWM converter power stages and their compensation circuits. These techniques provide reduction of system order, and allow for the faster simulation without any numerical convergence problem. A buck converter with two-stage output filter Is employed to confirm the usefulness of the proposed techniques. The simulation results show these techniques can simulate the responoes of PWM converter system up to high frequencies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.967-974
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• 2017

Reaction wheel shows nonlinear torque response on low-speed region due to friction. Thus precise satellite attitude control on this region is hard to achieve. Previous research tries to solve this problem, by compensating friction or applying dither command. However, due to difficulties of drag torque modeling or frequent zero wheel speed crossing, these methods are not suitable to apply on the real satellite attitude control. To solve this problem, we propose the attitude controller gain adjustment method based on the attitude error.