• 한국산학기술학회논문지
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• 제13권10호
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• pp.4676-4685
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• 2012

본 연구는 저강도 원심성 운동과 동적 스트레칭이 지연성 근육통에 미치는 효과를 비교하고자 시행하였다. 본 연구의 대상자는 연구에 참여하기 5개월 전부터 하지에 규칙적인 운동을 하지 않았던 18명의 20대 건강한 여성을 대상으로 하였다. 대상자들은 전체 3그룹인 대조군, 저강도 원심성 운동군 그리고 동적 스트레칭군에 무작위로 배정되었다. 측정변수로는 최대 수의적 등척성 수축력, 초음파 영상을 통한 근 두께, 근 통증 척도, 무릎관절 가동범위이며 지연성 근육통 유발 전, 유발 후 24시간, 48시간, 72시간에 각각 측정되었다. 저강도 원심성 운동군과 동적 스트레칭군의 운동 프로그램은 지연성 근육통 유발 4주 전에 일주일에 3회씩 각각 시행되었다. 본 연구의 결과 최대 수의적 등척성 수축력과 근 통증 척도에서만 그룹간 유의한 차이가 있었으며(p<.05), 저강도 원심성 운동은 동적 스트레칭에 비해 근 통증 척도가 유의하게 감소하였다(p<.05). 그러므로 저강도 원심성 운동과 동적 스트레칭이 지연성 근육통의 증상 중 근 통증에 효과적임을 제시하며 또한 저강도 원심성 운동이 동적 스트레칭보다 근 통증을 빠르게 감소시킴으로써 근 통증에 더 효과적임을 제시하고자 한다.

• 한국터널지하공간학회 논문집
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• 제9권3호
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• pp.219-228
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• 2007

본 연구에서는 축소모형실험을 통하여 편토압 및 측압이 터널 거동에 미치는 영향을 연구하였다. 모형실험 결과의 타당성은 수치해석을 통하여 검토하였다. 터널에 작용하는 편토압을 감소시킬 수 있는 방안으로 편향 배치된 지보구조를 제안하고 이 방안의 적용성을 검토하였다. 실험 결과, 편향 배치된 지보구조를 적용함으로서 발생되는 변위가 전체적으로 줄어들었고, 초기 균열이 발생되는 하중도 증가되었다. 또한 터널의 안정성에 크게 문제가 되는 최대 편압 수직하중 역시 증가함을 알 수 있었다. 터널에 작용하는 측압의 영향을 검토한 결과, 측압계수의 변화에 따라 변위 발생 양상 및 균열 발생 양상이 매우 변화함을 알 수 있었다. 또한, 안정성 측면에서 취약점을 나타내는 부분도 변화함을 알 수 있었다.

• 한국전문물리치료학회지
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• 제14권4호
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• pp.1-6
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• 2007

This study examined the effects of hold-relax with agonist contraction (HR-AC) on the symptoms of delayed onset muscle soreness (DOMS) induced by intensive eccentric exercise of the non-dominant biceps brachii. Ten men (mean age=26.7 yrs, mean height=172.1 cm, mean weight=66.2 kg) and ten women (mean age=27.4 yrs, mean height=165.9 cm, mean weight=60.7 kg) who had not participated in a regular exercise program for the upper extremities in the previous six months were randomly assigned to one of two experimental groups: the HR-AC group, or the control group. We measured joint range of motion (ROM), maximal voluntary isometric contraction (MVIC), and muscle soreness before eccentric exercise, and 24, 48, and 72 hours after eccentric exercise. The subjects in the HR-AC group received the HR-AC technique in the non-dominant biceps brachii. The HR-AC technique was applied 24 and 48 hours after eccentric exercise. There was no significant difference between the HR-AC and the control group. However, the HR-AC group, compared to the control group, had a significant difference between the time points of the various parameters. Increased ROM (p<.05), decreased muscle soreness (p<.05), and reduced MVIC (p<.05) were found in the HR-AC group after 72 hours. Decreased ROM (p<.05) and MVIC (p<.05), and increased muscle soreness (p<.05) were observed in the control group. These findings suggest that the HR-AC technique effectively reduces muscle soreness and increases ROM 72 hours after eccentric exercise.

• Journal of Advanced Marine Engineering and Technology
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• 제40권4호
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• pp.320-324
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• 2016

본 연구에서는 일반 볼트와 달리 두께가 얇고 단면적이 넓은 편심원형 플랜지구조를 가진 캠버볼트의 편심단조공정을 제시하였다. 캠버볼트는 일반 볼트와 같이 축대칭 형상으로 단조 후, 플랜지 부분을 트리밍하여 가공한다. 따라서 단조과정에서는 높은 단조 하중과 대량의 칩이 발생한다. 이와 같은 문제점을 해결하기 위해 새로운 단조공정이 요구된다. 편심단조공정은 일반적인 단조공정과 달리 중심축에서 편심 된 상태로 가공하는 새로운 단조 공정이다. 또한 편심단조공정은 단조하중과 단조 후 트리밍 칩의 양을 줄일 수 있다. 이러한 캠버볼트의 편심단조공정설계를 위해 편심유도금형의 편심량과 금형형상의 최적화가 필요하다.

• 대한임상전기생리학회지
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• 제8권1호
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• pp.15-22
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• 2010

Purpose : This study examines the effects of pre-eccentric exercise and stretch ing to bicepsbrachii to prevent delayed onset muscle soreness and recovery of muscular function depending on the training intensity with 28 normal adults in their twenties. Methods : The subjects were divided into a control group, a group without any previous eccentric exercise, and a stretching group. Pre-eccentric exercise group conducted exercise with the intensity of 25% of maximal voluntary contraction. Pre-eccentric exercise and stretching was applied before to induce delayed onset muscle soreness and after, 24 hour post, 48 hour post, and 72 hour post. Measurements were conducted to examine pain and muscular function changes before, immediately after, and after inducing delayed onset muscle soreness. After inducing delayed onset muscle soreness, measurements were taken at the 24th hour, 48th hour, and 72nd hour. Results : The pre-eccentric exercise group and stretching group showed a significant difference from the control group by isometric contract ion power and mechanical pain threshold as a result of measuring delayed onset muscle soreness. Conclusion : From these results, electrical stimulation using presynaptic inhibition mechanism of transcutaneous electrical stimulation (TES) had positive effects for walking ability on inhibition of muscle tone in lower extremity. The motor level stimulation group experienced a more significant effect than the sensory level stimulation group. Therefore, the transcutaneous electrical stimulation (TES) is considered to be effective on walking ability increasing through inhibition of muscle tone in lower extremity for rehabilitation of post stroke hemiplegic patients.

• 설비공학논문집
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• 제27권12호
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• pp.652-658
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• 2015

The Bubble Jet Loop Heat Pipe (BJLHP) is designed to operate in the horizontal orientation. The motion of the bubble generated by boiling working fluid on a heater surface in the evaporating section of the BJLHP helps the working fluid transfer heat to the condensing portion. In this study, we changed the position of the heater in the evaporating section from concentric to eccentric. The concentric heater is located at the center of the tube in the evaporating part, and the eccentric heater is located at the bottom of the inner surface of the same tube. We used R-134a as the working fluid, and the charging ratio was 50%vol. We measured the temperatures of the evaporating and condensing sections by changing the input electric power from 50 W to 200 W, measuring every 50 W. The results of the experiment show that the effective thermal conductivity of BJLHP using an eccentric heater is four times higher than the BJLHP obtained using a concentric heater. Additionally, we conducted a visualization experiment on the evaporating portion of BJLHP to determine why the effective thermal conductivity was higher. The working fluid was water, and we took pictures of the flow visualization for BJLHP. Nucleate boiling with the eccentric heater was more intense and generated more bubbles. Therefore, the eccentric heater was more saturated by the liquefied working fluid.

• PNF and Movement
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• 제17권3호
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• pp.487-497
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• 2019

Purpose: This tutorial review investigated the effect of prior fatigue and passive stretches on eccentric contraction-induced muscle injuries, as well as the underlying mechanisms of eccentric contraction-related injuries. Methods: Contraction-induced muscle damage is the most common disabling problem in sports and routines. The mechanisms underlying the pathology and prevention of muscle damage lessened by prior fatigue or stretches are critical in assessing musculoskeletal injuries. Even though there are treatments to reduce eccentric contraction-induced muscle injuries, fatigue negatively influences them. Therefore, we reviewed previous studies on eccentric contraction-induced muscle injuries with prior treatments using the MEDLINE and PubMed databases. Results: Prior passive stretching had a preventative and therapeutic effect, but prior lengthening contractions did not. On the other hand, prior isometric contractions involving relatively small forces may not provide a sufficient stimulus to induce protection. As a result, high force isometric contractions may be necessary. The studies supported the positive effects of prior fatigue, concluding that it was a factor in determining the amount of damage caused by eccentric exercise. This was due to a reduction in force and increased temperature. Studies that did not support the positive effects of prior fatigue concluded that a shift in optimal length to a longer length and reduced energy absorption during lengthening are evidence that fatigue is not related to muscle injuries induced by lengthening. Conclusion: The variability of the experiment models, conditions, muscles, and treatment methods make it necessary to interpret the conditions of previous studies carefully and draw conclusions without making direct comparisons. Thus, additional studies should be carefully conducted to investigate the positive effect of fatigue on lengthening.

• 한국구조물진단유지관리공학회 논문집
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• 제24권1호
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• pp.116-124
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• 2020

코어 위치변화에 따른 횡력저항성능 분석을 위하여, 대칭 평면형 20층 건물을 대상으로 3차원 구조해석을 수행하였다. 중심 코어, 1축 편심 코어, 2축 편심 코어로 구분하여 4가지 해석모델을 구성하고, 고유치해석, 풍하중 해석, 지진하중 해석을 수행하였다. 중심 코어 건물에서는 비틀림이 발생하지 않았으나, 편심 코어의 배치에 따라 휨과 비틀림이 복합적으로 발생하였으며 횡력저항성능이 저하되었다. 코어의 편심 배치에 따른 풍하중 크기의 변화는 작으나, 최대 횡변위는 코어의 편심 배치에 의하여 크게 증가하는 것으로 확인되었다. 또한, 편심 코어의 경우 횡방향 강성의 저하로 인하여 중심 코어에 비해 지진하중이 다소 감소하였으나, 비틀림의 영향으로 최대 층간변위비는 크게 증가하는 것으로 확인되었다. 이러한 결과들을 바탕으로 코어의 위치에 따른 구조거동을 확인하고, 계획 및 설계 단계에서 코어 배치의 가이드라인으로 활용할 수 있다.

• Structural Engineering and Mechanics
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• 제80권6호
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• pp.749-765
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• 2021

Suspension bridges bear large eccentric live loads in rush hours when most vehicles travel in one direction on the left or right side of the bridge. With the increasing number and weight of vehicles and the girder widening, the eccentric live load effect on the bridge behavior, including bending and distortion of the main girder, gets more pronounced, even jeopardizing bridge safety. This study proposes an analytical algorithm based on multi-catenary theory for predicting the suspension bridge responses to eccentric live load via the nonlinear generalized reduced gradient method. A set of governing equations is derived to solve the following unknown values: the girder rigid-body displacement in the longitudinal direction; the horizontal projection lengths of main cable's segments; the parameters of catenary equations and horizontal forces of the side span cable segments and the leftmost segments of middle span cables; the suspender tensions and the bearing reactions. Then girder's responses, including rigid-body displacement in the longitudinal direction, deflections, and torsion angles; suspenders' responses, including the suspender tensions and the hanging point displacements; main cables' responses, including the horizontal forces of each segment; and the longitudinal displacement of the pylons' tower top under eccentric load can be calculated. The response of an exemplar suspension bridge with three spans of 168, 548, and 168 m is calculated by the proposed analytical method and the finite element method in two eccentric live load cases, and their results prove the former's feasibility. The nonuniform distribution of the live load in the lateral direction is shown to impose a greater threat to suspension bridge safety than that in the longitudinal direction, while some other specific features revealed by the proposed method are discussed in detail.

• 대한통합의학회지
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• 제11권1호
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• pp.87-98
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• 2023

Purpose : This study was to verify the effectiveness of eccentric training and to make clinical recommendations on detailed application methods by comparing the effects of changes in acromiohumeral distance (AHD), pain intensity, muscle strength, and functional performance after applying a 12-week eccentric training program (ET group) or concentric training program (CT group) for patients with partial rotator cuff (supraspinatus) tears with moderate to severe shoulder pain. Methods : A total of 29 subjects were assigned to either the "ET group (n=15)" or the "CT group (n=14)" through simple randomization and were measured in the same way at baseline before intervention, 4 weeks and 12 weeks after intervention. All subjects received a physical therapy program 12 sessions 3 times a week for the first 4 weeks, and physical therapy program, 12 sessions a week, from 4 weeks to 12 weeks, for a total 20 sessions. Ultrasound machine was used for AHD, visual analog scale (VAS) was used for pain intensity, electronic hand held dynamometer was used for muscle strength, Korean Constant shoulder score (K-CSS) used for functional performance. Results : AHD, pain intensity, and muscle strength did not show significant differences at 4 weeks, but improved numerically, and showed significant differences at 12 weeks (p<.05), showing superior results in the eccentric training group compared to the concentric training group. Functional performance showed significant changes at both 4 and 12 weeks (p<.05), and excellent results were also found in the eccentric training group. Conclusion : In patients with partial rotator cuff tears with moderate to severe shoulder pain, an eccentric training program increased acromiohumeral distance (AHD), reduced pain, and increased muscle strength. Therefore, it can be clinically presented as an intervention method that can quickly and effectively improve functional performance, which is the ultimate goal of physical therapy.