• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.319-322
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• 2007

철도차량의 피로수명예측은 안전성과 신뢰성을 확보하고 높은 품질을 위한 중요한 관점이다. 이것은 최적설계 과정에서 추가의 제한조건으로 최소 피로수명값을 사용해서 접근할 수 있다. 하지만 피로수명은 회수의 함수이기 때문에 최적설계 적용에 제약이 따른다. 본 연구는 피로수명예측을 위한 최적설계에 대해 2단계 반응표면모델의 응용을 제안한다. 적용 예제로 컨테이너 화차의 제동 브라켓 엔드빔의 피로파손 문제에 대해 제안한 방법의 유효성을 설명한다.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.1
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• pp.51-58
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• 2012

In this study, the active exercise load control system was developed that monitors patient's muscular condition based on EMG signals and controls the load by biofeedback in real-time. In order to select appropriate muscular parameter for the system, the pre-exercise test was performed to obtain EMG signals from healthy 12 males. Subsequently, the main exercise test was performed to evaluate the active exercise load control system based on IEMG: a selected muscular parameter, on healthy 10 males without musculoskeletal disorder. The accuracy and availability of developed system were confirmed through observing changes between exercise load and IEMG. A correlation was analyzed between the fatigue of muscles and RPE indicating the individual subjective fatigue. As a result, the active exercise load control system that was suggested in this study could be useful to control the initial load-balancing and the amount of exercise appropriate for individual in rehabilitation exercise therapy.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.491-497
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• 2014

The corrosion of steel reinforcement in reinforced concrete bridge decks significantly affects the degradation of the capacity. Due to the advantageous characteristics such as high tensile strength and non-corrosive property, fiber reinforced polymer (FRP) has been gathering much interest from designers and engineers for possible usage as a alternative reinforcement for a steel reinforcing bar. However, its application has not been widespread, because there data for short- and long-term performance data of FRP reinforced concrete members are insufficient. In this paper, seven full-scale decks with dimensions of $4000{\times}3000{\times}240mm$ were prepared and tested to failure in the laboratory. The test parameter was the bottom reinforcement ratio in transverse direction. The decks were subjected to various levels of concentrated cyclic load with a contact area of $577{\times}231mm$ to simulate the vehicle loading of DB-24 truck wheel loads acting on the center span of the deck. It was observed that the glass FRP (GFRP) reinforced deck on a restraint girder is strongly effected to the level of the applied load rather than the bottom reinforcement ratio. The study results showed that the maximum load less than 58% of the maximum static load can be applied to the deck to resist a fatigue load of 2 million cycles. The fatigue life of the GFRP decks from this study showed the lower and higher fatigue performance than that of ordinary steel and CFRP rebar reinforced concrete deck. respectively.

• Journal of Digital Convergence
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• v.12 no.6
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• pp.425-432
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• 2014

The purpose of this study was to examine the effect of myofascical release (MR) on the degree of pain and nerve conduction velocity (NCV) in middle-aged women. Participants were 28 middle-aged women and MR carried out three times (1, 3, 5 day) at intervals of two times. We did survey about changes of pain before the MR and how they changed after the MR. Also measured pressure pain threshold (PPT) and visual analogue scale (VAS) by using the algometer at trapezius muscle. In median nerve, we did motor nerve conduction velocity (MNCV) test and sensory nerve conduction velocity (SNCV) test for measuring incubation period, amplitude and nerve conduction. The most painful time was 18~21 and the most painful part was shoulder. The pain scale, PPT and VAS after the MR had significantly decreased than before the MR. The latency was significantly decreased and the amplitude was significantly increased in the MNCV and the latency was significantly decreased in the SNCV after the MR. Also it was effective in ameliorating pain scale and latency of NCV. Consequently, the MR can be effective in prevent pain scale caused by fatigue in middle-aged women as replacement therapy.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.329-336
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• 2019

The purpose of this study is to analyze the differences of the lower back pain, fatigue, and Achilles tendon thickness according to wearing and not wearing high heels in order to understand symptoms of musculoskeletal diseases caused by wearing high heels in college students. lower extremity pain fatigue and achilles tendon thickness were measured in high heel wear group (n=19) and non high heels wear group (n=23). Participants' general characteristics and the lower extremity pain, fatigue, and Achilles tendon thickness were analyzed using mean, standard deviation. Differences in lower extremity pain, fatigue, and achilles tendon thickness were analyzed by independent t-test. The results showed that the difference between the participants' lower extremity pain (t=2.28, p=.028), right achilles tendon thickness (t=2.30, p=.027) and left achilles tendon thickness (t= 3.89, p<.001) The results of this study show that convergence approach can be applied as a basis for health problems in the structure and function of musculoskeletal disorders associated with wearing high heels. In the future, follow up observation according to the wearing of high heels in the same subject will be needed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.973-974
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• 2013

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.1
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• pp.114-120
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• 2018

In this paper we implemented an EMG sensor system for wearable devices to obtain and analyze of EMG signals. The performance of the implemented sensor system is evaluated by the correlation analysis of muscle fatigue and muscle activation to clinical EMG system and compared with power consumption of the measured power of our system and commercial systems. In experiments with biceps and triceps brachii of 5 objects, The correlation values of muscle fatigue and muscle activation between our system and the clinical EMG system is 1.1~1.4 and about 1.0, respectively. And also the power consumption of our system is 25~50% less than that of some commercial EMG sensor systems.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.207-212
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• 2005

The purpose of this work is to develop the FES controller that can cope with the muscle fatigue which is one of the most important problems of current FES (Functional Electrical Stimulation). The feasibility of the proposed FES controller was evaluated by simulation. We used a fitness function to describe the effect of muscle fatigue and recovery process. The FES control system was developed based on the biological neuronal system. Specifically, we used PD (Proportional and Derivative) and GC (Gravity Compensation) control, which was described by the neuronal feedback structure. It was possible to control of multiple joints and muscles by using the phase-based PD and GC control method and the static optimization. As a result, the proposed FES control system could maintain the cycling motion in spite of the muscle fatigue. It is expected that the proposed FES controller will play an important role in the rehabilitation of SCI patient.

• Science of Emotion and Sensibility
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• v.19 no.1
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• pp.3-10
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• 2016

This research was to investigate the effect of fatigue reduction and heart rate recovery (HRR) according to whole body vibration (WBV). 20 healthy participants were recruited and divided into vibration group (VG) and none vibration group (NVG). VG was group with provided vibration and NVG was group without vibration. They exercised slope gait with 8.5 degree and 4km/h during 30min. They rested on the chair type vibrator during 30min. The vibration consists of 10hz as frequency and 5mm as amplitude. We measured the lactate in the blood and HRR before, immediately after exercise and after rest session. The results showed that lactate level in VG the more decreased at 95.2%. The result of HRR was similar including recovery at 50.67% in VG. The WBV with stimulated vessel in muscle assisted the recovery function by reducing the excess post-exercise oxygen consumption (EPOC) quickly and improving blood circulation. The rest with WBV could provide efficient cool-down exercise for elderly and women without other physical activities after exercise.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.621-624
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• 2000

중량물을 다루는 작업들 중 허리를 이용한 들기 작업은 LBP(Low Back Pain) 및 기타 상해들을 유발한다. 실제 작업장에서 허리 상해에 대한 문제가 중요하게 부각됨에도 불구하고, 허리근육을 대상으로 피로회복의 효과에 대한 연구가 적절하게 제시되고 있지 않은 실정이다. 본 연구에서는 이같은 문제점을 해결하기 위해 Sub-maximal상태에서 유발된 근육의 피로가 초기 상태로 회복되기 위한 휴식시간을 EMG를 통하여 정량적으로 산정하였다. 그 결과, 휴식시간에 따른 피로 회복이 통계적으로 유의한 차이를 보였다. 본 결과는 허리요소작업이 들어 있는 실제작업장에서 작업의 반복에 따른 적절한 휴식시간을 정량적으로 제시하는데 필요한 기초자료를 제공함으로써 허리에 관련된 근골격계 질환을 예방하고자 하는데 이용될 수 있는 것으로 기대한다.