• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.13-25
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• 2012

Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1A
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• pp.7-15
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• 2008

In this paper, it is investigated that the limitation due to the asymmetry of optical power with respect to optical phase conjugator(OPC) in mid-span spectral inversion(MSSI) for compensating optical signal distortion due to group velocity dispersion(GVD) and nonlinearities generated in fiber by combining with lumped dispersion management(DM) technique into MSSI. Two kinds of lumped DM configuration(configuration A and configuration B) are considered and compared each other in this research. Configuration A consists of two dispersion compensating fiber(DCF) span positioned after transmitter and before receiver, respectively. Configuration B consists of two dispersion compensating fiber(DCF) span positioned before and after OPC placed at middle of total transmission link, respectively. It is confirmed that the transmission performances are more improved by the configuration A combined with MSSI than configuration B. Also, it is confirmed that the best performance of overall channels are obtained by making net residual dispersion(NRD) to have positive value in self phase modulation(SPM)-limited WDM transmission systems, irrelevant to the configuration of DM.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.792-800
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• 2021

This paper presents a new structure for a linear active magnetic bearing using a Halbach magnet array. The proposed magnetic bearing consisted of a Halbach magnet array, center magnet, and single coil. The proposed linear active magnetic bearing has a high dynamic force compared to the previous study. The high dynamic force could be obtained by varying the thickness of a horizontally magnetized magnet. The new structure of Halbach linear active magnetic bearing has a high dynamic force. Therefore, the proposed linear active magnetic bearing increased the bandwidth of the system. Magnetic modeling and optimal design of the new structure of the Halbach linear active magnetic bearing were performed. The optimal design was executed on the geometric parameters of the proposed linear active magnetic bearing using Sequential Quadratic Programming. The proposed linear active magnetic bearing had a static force of 45.06 N and a Lorentz force constant of 19.54 N/A, which is higher than previous research.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.10a
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• pp.402-408
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• 1997

일정 학습계수와 이진 강화함수를 지닌 자기조직화 형상지도(Self-Organizing Feature Map)신경회로망을 FPGA위에 하드웨어로 구현하였다. 원래의 SOFM 알고리즘에서 학습계수가 시간 종속형인데 반하여, 본 논문에서 하드웨어로 구현한 알고리즘에서는 학습계수가 일정인 값으로 고정되며 이로 인한 성능저하를 보상하기 위하여 이진 강화함수를 부가하였다. 제안한 알고리즘은 복잡한 곱셈 연산을 필요로 하지 않으므로 하드웨어 구현시 보다 쉽게 구현 가능한 특징이 있다. 1개의 덧셈/뺄셈기와 2개의 덧셈기로 구성된 단위 뉴런은 형대가 단순하면서 반복적이므로 하나의 FPGA위에서도 다수의 뉴런을 구현 할 수 있으며 비교적 소수의 제어 신호로서 이들을 모두 제어 가능할 수 있도록 설계하였다. 실험결과 각 구성부분은 모두 이상 없이 올바로 동작하였으며 각 부분이 모두 종합된 전체 시스템도 이상 없이 동작함을 알 수 있었다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.175-181
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• 2009

In this paper, it is suggested that the selection method of parameter of Power System Stabilizer(PSS) with robustness in low frequency oscillation for Static VAR Compensator(SVC) using a self tuning fuzzy controller for a synchronous generator excitation and SVC system. The proposed parameter self tuning algorithm of fuzzy controller is based on the steepest decent method using two direction vectors which make error between inference values of fuzzy controller and output values of the specially selected PSS reduce steepestly. Using input-output data pair obtained from PSS, the parameters in antecedent part and in consequent part of fuzzy inference rules are learned and tuned automatically using the proposed steepest decent method.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.237-245
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• 2016

Anxiety for employment of workers has been increased due to rapid change of management environment, which tends to increase psychological instability on the job of all workers. Accordingly, this study examined the moderating effect of self-efficacy between job instability and organizational citizenship behavior. The research subjects were employees of small and medium companies in the manufacturing industry in Daejeon-si, Sejong-si and Chungcheongnam-do and Chungcheongbuk-do. 500 sheets of the questionnaire were distributed from August 5, 2015 to August 30, 2015. Among them, 321 were collected with 64.2% of the response rate. Total 312 sheets were used for analysis excluding 9 sheets with incomplete answers. The results are as follows. Firstly, it proved that job instability had negative (-) effect on organizational citizenship behavior. Secondly, in the relation between job instability and organizational citizenship behavior, there was moderating effect of self-efficacy. Accordingly, if self-efficacy of the workers is higher in the threat of job instability, it means organizational citizenship behavior would increase. In conclusion, in the current situation where there is instable survival of corporation and job, the management of small and medium manufacturing company needs to increase self-efficacy through training and internal reward to employees. The limit of the study is that the research subjects were employees of small and medium companies in the manufacturing industry in Daejeon-si, Sejong-si and Chungcheongnam-do and Chungcheongbuk-do. Accordingly, as situational peculiarity may be observed, it is required to have expanded study to more various areas, works and industries.

• Journal of Convergence for Information Technology
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• v.10 no.2
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• pp.21-31
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• 2020

This study tested the effectiveness of commercialized smartphone apps in improving walking activities among college students. 66 participants were randomized into each of four groups that was used different behavior change strategies: monetary rewards app, goal setting and feedback app, gaming app, and self-monitoring control group. 45 participants who completed the experimentation was included in data analysis. Repeated measures ANOVA resulted in statistically significant time by groups interactions in recorded step counts, self-reported completed plans and self-reported walking activities scores. The Goal-setting and feedback group and the gaming group resulted in increase in both step counts and completed plans. The results were discussed in the framework of behaviorism.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.11
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• pp.1043-1049
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• 2007

Data transfer rate and storage capacity are main criteria of the performance of the optical disk drive. The highest data transfer rate and the largest storage capacity is most desirable. To increase these performances, the actuator of the optical disk drive should have a high servo bandwidth to compensate the vibration of an optical disk. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to increase the natural frequencies of the flexible modes. In this paper, we suggested a moving magnet type actuator having high frequencies of the flexible modes. Generally, the moving magnet type actuator has an advantage to increase the natural frequencies of the flexible modes because the moving magnet type actuator has simple structure and the Young's modulus of magnet is high. However, large moving mass and inefficiency of EM(electromagnetic) circuit cut down driving sensitivities of the actuator. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and the natural frequencies of the flexible modes were improved by using DOE(design of experiments) for electromagnetic circuit and modifying the lens holder.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.50-56
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• 1999

This paper presents consideration on validity of instantaneous correlation power theory. The proposed power theory is defined and analyzed by time domain approach, thus it is easy to understand and instrument. The power is decomposed into active, fundamental reactive and harmonics components based on the autocorrelation and crosscorrelation signal techniques between voltage and current waveforms. On the compensation property, active power filter deal with three components only. Also, for real time control of active power filter, the power models with difficult concept are not cost effective. To verify the validity of the instantaneous correlation power theory, experimental work for voltage type DSP based active power filter is achieved. The power of thyristor controlled motor drives is decomposed into three orthogonal components by proposed power theory. From compensation results, validity of proposed theory is confirmed. feedback controller needs the information on some motor parameters. New recursive adaptation algorithms for rotor resistance and mutual inductance which can be applied to our nonlinear feedback controller are also presented in this paper. The recursive adaptation algorithms make the estimated values of rotor resistance and mutual inductance track their real values. Some simulation and experimental results show that the adaptation algorithms are robust against the variation of stator resistance and stator inductance.

• Monthly Duck's Village
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• s.81
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• pp.54-60
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• 2010

2006년 기준으로 1천8백만 수수의 육용오리가 사육되고 있는 영국에서는 오리 사육시 복지적인 측면에서의 생산 시스템에 대하여 여러 의견이 나오고 있다. 자연에서 물과 오리의 상관관계에도 불구하고, 오리가 몸을 담그거나 헤엄칠 수 있는 등 활동에 필요한 물을 제공해야한다는 어떠한 법적 규제도 마련되어 있지 않다. 어떤 경우에는 오리들이 머리를 물에 담글 수 있게 트러프(홈통형 물통)을 제공하기도 하지만 어떤 경우에는 니플 급수기를 통해서만 물에 접근할 수 있기도 하다. 유럽평의회는 오리들이 머리를 담그고 깃털을 적실 수 있는 형태로 물을 제공할 것을 권장한다. 우리는 이번 연구에서 오리의 복지가 자연 및 물의 접근 허용 점위와 관련이 있다는 것을 밝히고자 오리의 몸과 깃털 상태를 기록하는 한편, 물 제공에 따른 복지 수준을 평가하기 위해 3자기 행동 평가를 하였다. 오리들은 욕조(작은 연못), 트러프, 샤워시설, 니플급수기, 5주령까지 니플 급수기만 제공하고 이후 욕조를 이용하는 등의 5가지 방법으로 물에 접근할 수 있도록 하였고, 이는 1)한 시설에서 오리가 보내는 시간, 2)욕조가 주어졌을 때 오리들의 보상행동, 3) 오리들이 가장 선호하는 시설을 기록하여 오리의 행동을 평가하였다. 이를 통해 오리들이 머리를 담그고 깃털을 정리할 수 있는 물을 제공하지 않으면 오리들이 코나 깃털을 깨끗이 유지할 수 없다는 결론을 얻을 수 있었다. 중요한 것은 욕조, 트러프, 샤워기를 통해 물을 제공해 주었을 때 물에서 목욕(bathing)을 하며 보낸 시간은 모두 동일하였다는 사실이다. 그러나 니플 급수기에서 목욕행동(bathing movement)을 한 시간은 아주 짧았으며, 니플 급수기 만으로 사육되었던 오리군의 욕조시설을 제공하였을 때는 '보상 반등행동'을 보였다. 트러프나 샤워시설이 제공되었던 그룹에서는 보상행동을 보이지 않아 이러한 시설들이 욕조와 동일한 작용을 하는 것으로 볼 수 있다. 또, 오리들에게 선택권이 주어졌을 때 오리들은 욕조에서 헤엄을 치고, 샤워시설에서 물을 마시고 장난치는 것을 선호하는 것으로 나타났다. 다른 시설들이 제공되었을 때 오리들은 니플 급수기에서 거의 시간을 보내지 않았다. 이번 연구를 통하여 육용 오리의 사육 환경의 복지 개선을 위해 트러프나 샤워 시설로 실제 욕조(작은 연못) 만큼 긍정적인 효과를 얻음을 확인 할 수 있었다.