• Computational Structural Engineering
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• v.9 no.4
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• pp.135-140
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• 1996

Single angle or channel with thin-walled open section can be used as compression member for example as web member in truss. In this case the inevitable eccentricity due to fabrication is commonly neglected in structural design. However eccentricity effect should be considered in the member design, especially in case of compression member. The critical loads of compression members that buckle by twisting or by a combination of bending and twisting are to be determined by solving governing differential equations. In this paper, the investigations are limited to the rolled channels([), equal-leg angles(L), lipped channels(C) and the applied loads are assumed to have some eccentricities.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.7
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• pp.539-546
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• 2002

This paper presents a new direct seek control scheme that provides fast data access capability and robust performance for high-speed rotational optical disk drives (ODD). When a disk is rotating at a high speed to obtain fast data transfer in ODD, the magnitude and frequency of velocity disturbance caused by eccentric rotation of the disk increase in proportion to the rotational speed of the disk. Such disturbances make it almost impossible for the conventional seek control scheme to achieve stable and satisfactory seek performance. We analyze the problems that may arise when the conventional seek control scheme is applied to the high-speed rotational ODD and propose a new direct seek control scheme that will solve such problems. In the proposed scheme, a seek control system is designed such that its performance is guaranteed for a set of plants with parameter perturbations. The performance of the proposed seek control scheme is shown by experiments using a high-speed rotational ODD.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.117-123
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• 2003

Rotational machines such as optical disk drives, hard disk drives, and so on are subject to periodic disturbances caused by their mechanical characteristics. In the meanwhile, it is well known that repetitive control rejects periodic disturbance effectively. This paper presents a practical application of repetitive control to the track-following servo of an optical disk drive. The repetitive control system is composed of two repetitive controllers which compensate for periodic disturbances generated by track geometry and eccentric rotation of disk and a feedback controller stabilizing the feedback loop. A robust stability for all plant uncertainties is proved using linear matrix inequalities (LMIs). In the controller design, a weighting function is introduced for the feedback controller to ensure a minimum loop gain and a sufficient phase margin. The repetitive controllers and the feedback controller are designed by solving an optimization problem which can consider the robust stability condition and the system performance. The developed repetitive control system is implemented in the digital control system with a 16-bit fixed-point digital signal processor (DSP). Through simulation and experiment. The feasibility of the proposed repetitive control system is verified.

• The Journal of Korean Physical Therapy
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• v.17 no.4
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• pp.469-476
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• 2005

Purpose: The purpose of this study was to evaluate effect of kinesio taping on the delayed onset muscle soreness(DOMS). Methods Fourteen healthy subjects were randomly divided into two groups; experimental group(n=7) and control group(n=7). All subjets performed eccentric exercise of knee extensor until exhausted. After 24 hours experimental group was taped with kinesio tape to the quadriceps muscle and control group was not applied. To compare with the effectiveness of kinesio taping between two groups, I measured DOMS with pain(VAS) and temperature(DITI). The data were analyzed by Independence T-test. Results: The Experimental group was not significantly different the body temperature and pain than Control group at 24 hours after exercise without taping. The Experimental group was more decreased pain and temperature than Control group at 24 hours after exercise with taping. The Experimental group was more decreased pain than Control group at 48 hours after exercise. The Experimental group was more decreased pain and temperature than Control group at 72 hours after exercise. Conclusion: Experimental group more rapidly recovered temperature and more rapidly decreased pain after apply taping than control group.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.99-104
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• 2002

In this paper the influence or specimen length on flexural compressive strength and parameter or equivalent rectangular stress block of polymer concrete was evaluated. For this purpose, a series of C-shaped specimens subjected to eccentric compression were tested using four different length-to-depth ratios(from 1.0, 2.0, 3.0 and 4.0) of specimens with compressive strength of 1,020kgf/cm$^2$. Results indicate that for the region of h/c$\leq$3.0 the reduction in equivalent rectangular stress block depth and flexural compressive strength with increase of length-to-depth ratios was apparent but for the region of h/c$\geq$3.0 they were nearly constant. It means that for the region of h/c$\geq$3.0 effect of specimen length on equivalent rectangular stress block depth and flexural compressive strength was negligible. It was also founded that the effect of specimen length on v, a coefficient of strength, that was from 0.84 to 0.86 regardless of h/c was petty. Finally, predictive equation is, suggested by using modified law of effect of specimen length and results.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.149-153
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• 2003

AC 부하를 갖는 동기전동기에 있어서, 동기전동기의 속도리플을 저감시키기 위한 문제를 풀기위해 3가지 제어기법에 대해 비교를 한 후 가장 강인한 제어기법에 대해 분석하였다. AC 부하를 갖는 특별한 제어 대상으로 엑스선 전산화 단층촬영 장치(CT)용 겐트리를 선정하였으며 시스템이 갖는 특별한 구조에 의해 이러한 시스템 특성을 갖는다. 동기전동기의 출력 축에 링(Fing) 모양의 원판 프레임을 갖으며, 이 원판 표면에 무게가 서로 다른 여러 장치(X_선 튜브, X-선 검출기, 고압발생장치, DAS 장치, 온도조절장치 등)를 부착하여 영상 획득 시스템의 회전부를 구축하기 때문이다. 이러한 시스템에서는 무게 평형을 갖지 못하는 편심 무게가 존재하게 되며 이로써 전동기 관점에서는 AC 부하처럼 인식되는 제어 조건으로 인식 될 수 있다. AC 부하를 갖는 동기전동기에 대해 일반적인 벡터제어 알고리즘으로 제어를 수행하면 정상상태에서도 속도 오차가 "0" 으로 줄어들지 않고 AC 형태의 오차 성분이 존재하며 편심 무게의 크기에 비례하여 진폭이 커지는 특성을 갖는다. 이러한 문제점을 해결하기 위하여 Sine파 보상전류를 갖는 속도제어기법, 펀심부하토크 관측기를 이용한 속도제어기법, 그리고 기준모델제어기법을 소개하였다. 각 방법에 대한 실험 결과로부터 편심무게의 변동과 편심 위치의 변동 조건에서 기준모델제어기법이 강인한 제어 특성과 리플저감 측면에서 가장 우수함을 검증하였다. 이로써 AC 부하 조건에서 고정도 속도 제어기가 요구되는 경우 좋은 선택의 지침이 될 수 있다고 본다.

• The Journal of Korean Physical Therapy
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• v.29 no.1
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• pp.39-43
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• 2017

Purpose: This study was to investigate the effects of unilateral muscle fatigue in knee and ankle joints on balance and gait in healthy adults. Methods: Exercise inducing muscle fatigue in the knee joint consisted of concentric and eccentric contraction of dominant knee extensors in healthy adults by using the Leg Extension Rehap exercise machine (HUR, Finland). Exercise inducing muscle fatigue in the ankle joint was composed of voluntary contractions and forced contractions of the dominant plantar flexors in healthy adults. Exercises to induce muscle fatigue in the knee and ankle joints were performed until the subject complained of fatigue or pain, the occurrence of muscle fatigue was confirmed by electromyography. We measured static and dynamic balance using the Good Balance system and gait performance by RS-scan. Results: Static and dynamic balance ability and spatial-temporal gait decreased significantly after muscle fatigue in knee and ankle joint. Conclusion: These results show that unilateral muscle fatigue of the lower extremities affected postural control and gait. Therefore, therapists and sport trainers should minimize the risks of fall and injuries related to unilateral muscle fatigue.

• The Korean Journal of Cytopathology
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• v.8 no.2
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• pp.164-169
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• 1997

A case of plasmacytoma of the ovary and breast, which developed in a patient with a solitary plasmacytoma in the lumbar vertebra for nine months, was diagnosed cytologically and histologically. Enlargement of the right ovary and multiple palpable masses in the right and left breast were already present at six months after the diagnosis of vertebral solitary plasmacytoma. At eight months, plasma cell leukemia developed, and nine months the enlarged both ovaries, replaced by yellowish-gray solid tumors showed infiltration of immature plasma cells. The cytologic features of the ovarian tumors were same with those of the breast tumor. The tumor cells were of predominantly immature plasma cells with one or more nuclei. Some mature plasma cell had an eccentric nucleus with single nucleolus and peripherally clumped chromatin. Binucleated or multinucleated giant cells were often present. Histologically, sheets of poorly differentiated plasmacytoid tumor cells were separated by strands of hyaline fibrous tissue. On immunohistochemical stains, the tumor cells showed strong reactivity for lambda-light chain but no reaction for kappa-light chain, cytokeratin, or leukocyte common antigen.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.4 s.15
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• pp.63-71
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• 2004

The centroid of rail doesn't coincide with the centroid of stringer on target truss bridge. If there is no eccentricity on the bridge, bending stress works only. But in the real design and execution, not only bending stress works but also torsional stress does because of it's eccentricity. So this study evaluates how much the torsional stress by eccentricity effects joint members on the bridge. We investigate the possibility to control torsional stress if we model longitudinal bracing between stringers.

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.88-98
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• 1990

The purpose of this study was twofold : first, to reduce as much as possible the shaking moments of the crank-type transplanting mechanism of walking-type rice transplanters, and second, to evaluate whether or not a crank-type transplanting mechanism, if its shaking moment is reduced, can be used in riding-type transplanters for high speed transplanting operations. For these purposes, kinematic and force analyses of the currently available crank-type transplanting mechanisms were made and their results were compared with those observed by experimentation. The degree of shaking moment effect was also estimated Various efforts to minimize the shaking moments led to the development of a crank-type mechanism with a balancing gear, in which an eccentric balancing gear is combined into the driven link axis. Analysis of the developed mechanism showed that about 20% of the shaking energy can be reduced and about 40% of reduction in peak shaking moment can be obtained when comparing with those obtained without the balancing gear. It was concluded that crank-type transplanting mechanisms can be used for high speed operations with a forward speed of 0.9-1.2m/s if the balancing gear is additionally mounted. However, further considerations must be made to solve the space constraints in relation to the structural frame of riding type of rice transplanters.