• Korean Journal of Applied Biomechanics
• /
• v.21 no.4
• /
• pp.405-410
• /
• 2011

The purpose of this study was to compare the differences in kinematic variables and grip forces among professionals(PG), amateurs(AG), and novice group(NG) during golf putting. The participants consisted of 3 groups based on their playing ability: 8 professional golfers (handicap<5), 8 amateurs (handicap<18) and 8 novice. Each subject attempted 2.1m putts from the hole. 3D motion analysis system(Motion analysis Corp., USA) with 6 high speed cameras and grip force measurement system(Kim et al., 2007) were used to acquired kinematic and force data, respectively. To compare differences among groups, joint angles of upper limbs, trajectory and smoothness by jerk cost function(JC) of putter head and grip forces were used in this study. Results showed that there were significant differences among groups in most of variables such as joint angles, trajectory & smoothness of putter head, and distribution of grip force in both hands. In brief, we confirmed that putting stroke in PG was more accurate and smooth than that in other groups, especially NG, due to their well-controlled upper limbs and keeping grip forces constant in both hands. It can be concluded that due to skilled levels, fundamental differences of putting movement could be identified and these differences might be helpful for improving one's putting skills.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2017.04a
• /
• pp.59-59
• /
• 2017

무인 헬리콥터의 양력을 개선하기 위한 익형 설계 단계로서 두꺼운 익형(V1505A)과 얇고 처진 익형(V2008B)의 기본 두 익형의 특성을 예측하는데 있어 회전하는 블레이드의 현실적 조건을 반영한 3D 모델을 마련하고 성능을 예측하였다. Fluent를 이용한 400 mm 선형모델의 시뮬레이션에서는 V1505A 익형은 높은 받음각에서 안정적인 특성을 보인 반면 V2008B는 비교적 높은 동력효율 특성을 보였으나, 높은 받음각에서는 실속 이후 양력이 급락하는 특성을 나타낸다. 형성된 노드 수는 약 870,000개로 하였다. 시위길이 135 mm인 익형 V2008B의 형상은 ANSYS (Fluent v16.2)를 이용해 반경(길이) 1,502 (1,380) mm 의 로터 블레이드를 구성하였다. 충분하지 않은 유동장이 익형 표면에서의 유동의 영향에 영향을 주지 않도록 직경 20 m의 원방경계(far field)를 형성하였다. 사용된 매쉬의 형태는 정사면체 형태로 로터 표면으로부터의 첫 번째 두께 높이는 0.001 m이고 10개의 층으로 형성하였다. 정지 비행하는 헬리콥터의 상태를 가정하여 회전좌표계를 이용하여 정상상태의 유동을 해석하고 사용된 난류모델은 넓은 영역에서의 유동을 고려하여 Realizable $k-{\varepsilon}$ 모델을 사용하였다. 내측그립 받음각 $6{\sim}22^{\circ}$에 대하여 현실적인 회전속도를 연동하여 600~1000 rpm을 적용하였다. 반복수(iteration)는 2000으로 하여 잔차값(residual)이 충분히 수렴하도록 하였다. 전체적으로 실제 헬리콥터가 발휘하는 양력보다는 낮은 수치로 예측되었으며 모델 및 해석 조건에 대한 검토가 필요해 보인다. 양력 값은 받음각 $10^{\circ}$에서 자중(약 68 kgf)을 극복하였고 받음각 $12^{\circ}$에 유상하중 20 kgf을 발휘하며 888 N의 양력을 보였다, 이어 받음각 $22^{\circ}$에서 실속 현상이 발생하였다. 받음각이 증가함에 따라 항력 역시 증가하였으며 받음각 $12^{\circ}$에서 121 N이었고 실속에 이르며 항력은 갑자기 증가할 것으로 예측된다. 본 연구는 변이 익형 개발의 선행 단계로 기본 익형에 대한 공력특성을 CFD 시뮬레이션을 통하여 예측하였다. 예측 값은 현실적 실험방법을 통하여 검증이 되어야 하며 이후 변이익형에 대한 예측과 설계가 가능하다.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.3
• /
• pp.65-74
• /
• 2006

This study was attempted to Kinematical characteristics of the Endo $360^{\circ}$El-grip Swing on the horizontal bar. To do this, we selected and analyzed the performance of two athletes who did Endo $360^{\circ}$El-grip Swing in the horizontal bar competition of male artistic gymnastic in the 22nd Universiad Games 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using two video cameras. In point of analyzing the actual competition situation, it is expected that gymnastics and coaches have the effective informations, and the following conclusion had resulted. 1. When performing Endo $360^{\circ}$El-Grip, the average for entire required time was $1.93{\pm}0.06sec$. The average for descent phase time was $0.24{\pm}0.02sec$, ascent phase time was 0.22${\pm}0.07sec$, connecting phase time was $0.87{\pm}0.07sec$, and El-Grip phase time was $0.61{\pm}0.02sec$. The descent phase need short period of time but however to have a stable performance, ensuring ascent and connecting phase time are needed. El-Grip phase need short period of time to have a stable re-grasp. 2. To have a convenient preparation for El-Grip in descent and ascent phase, lowering CM, and ease up in sway and plunge from the High Bar would make descent and ascent even more faster and would have increase effect in trunk rotation. 3. In descent and ascent phase, if shoulder angle and arm slope is dwindling then it would effect rotation angle so might risk it from hitting a Bar when putting legs in and out. 4. In connecting phase, it requires some time to show stable performance when El-Grip phase is continued by using hip angle which would make trunk rotation angle bigger and make descent and ascent time slower. 5. In El-Grip phase, when doing motions like hand standing. using hip angle more than maximum would make CM even faster and it is stable position while performing.

• Journal of The Korean Society of Integrative Medicine
• /
• v.8 no.1
• /
• pp.47-56
• /
• 2020

Purpose : The purpose of this study was to determine the effects of upper extremity volume, pain, and range of motion after participation in thera-band exercises according to the hand grip type in patients with breast cancer with upper extremity edema. We also aimed to determine the most efficient type of grip. Methods : The subjects were 10 female patients diagnosed with stage 2 breast cancer who had stage 2 lymphedema. Randomly, 5 patients each were allocated to the experimental and control groups. For six weeks, the patients in both the experimental and control groups exercised daily. In both groups, manual lymph drainage was applied for 1 hour. Afterward, patients in the experimental group placed their hands in the thera-band ring and exercised with their fingers outstretched. Patients in the control group exercised while holding the thera-band ring with a finger. Both the experimental group and the control group underwent measurements of the circumference of the upper extremity, pain, and range of motion of the shoulder joint at weeks 1, 2, 4, and 6 before and after exercise. Results : The upper arm circumference decreased by more in the experimental group in all weeks than before than that in the control group, and there was a statistically significant difference at 6 weeks. Compared with the difference between pre-exercise and 6 weeks post-exercise, the change in pain significantly decreased in the experimental group and showed a statistically significant difference. The shoulder range of motion increased in extension, external rotation, and internal rotation compared with that in the control group, and there was a statistically significant difference. Although the operating range increased in flexion and abduction, there were no statistically significant differences. Conclusion : In this study, we found that thera-band exercises with an open-hand grip are more efficient than thera-band exercises with a closed-hand grip in edema reduction, pain, and range of motion. In addition, it was found that it was more effective to continue the thera-band exercises with open-hand grip extended for at least 6 weeks rather than for a short time.

• 한국사회복지학회:학술대회논문집
• /
• 2002.04a
• /
• pp.497-531
• /
• 2002

It is very important for rehabilitation to deal with psychological aspects of persons with disabilities, as well as efforts improving the institutional and environmental conditions. A majority of persons with severe disabilities in the situation of Korea have difficulty in having and maintaining a job. Work should and would be a source of self-respect and material well-being in this modern society. Therefore, Vocational rehabilitation services are measures in restoration of family functions and social participation of persons with disabilities. This study aims at investigating linguistic characteristics and the validity of constructional concepts of picture interest test Inventories that have been utilized for the segregated groups of people such as persons with developmental disabilities. Picture interest test inventories seemed to be valid for measuring psychological traits and characteristics of people with mental retardation, and this finding can be extended to the group of other developmental disabilities, such as learning disabilities and mild/moderate behavioral deficits. The Holland classification system seemed to be best fitted for developing a comprehensive and accurate vocational interest inventory.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.35 no.2
• /
• pp.147-155
• /
• 1999

In this study, the stability analysis of a fishing vessel in a seaway was done. The stability analysis is an important item in the ship design, and so the ship registers of each nation constrain the ships to be followed the stability criterion. Stability variation, exciting forces due to wave and wind, and the broaching phenomena cause the capsizing of a ship. In this study, the stability analysis to study of the capsizing of a fishing vessel was performed. The relation between the speed of the ship and the wave length, that makes the encountering frequency vanish, was obtained. It was found that the encountering frequency tend to be zero when the wave whose length and direction are similar to those of ship. In this case, the possibility of dangerous situation becomes high. The calculated restoring arm becomes small when the ship is located near the wave crest. In general, the selected small fishing vessel is better than the large ship with respect to the stability, however the wave height becomes relatively high because of her small length Kim(l994) calculated the stability variation of the large cargo ship, the results of which showed the changes in stability great. But in the selected small fishing vessel in this study, the changes was small in comparison with the larger ship. This reason seems to be the shape of her midship section. In large cargo ships, the block coefficient is large, but that of the fishing vessel is relatively small and the small fishing vessel has chine, therefore the center of buoyancy moves much when the ship is inclined. It is desirable that the dynamic stability analysis for a fishing vessel, whose speed and direction are similar to those of waves, shall be done in the near future.

• Journal of Bio-Environment Control
• /
• v.28 no.4
• /
• pp.322-327
• /
• 2019

This study was conducted to improve the performance of automatic grafting robot using image recognition technique. The stem diameters of tomatoes and cucumber at the time of grafting were $2.5{\pm}0.3mm$ and $2.2{\pm}0.2mm$ for scions and $3.1{\pm}0.7mm$ and $3.6{\pm}0.3mm$ for rootstocks, respectively. The grafting failure was occurred when the different height between scions and rootstocks were over 4 mm and below 2 mm due to the small contact area of both cutting surface. Therefore, it was found that the height difference at the cutting surface of 3 mm is appropriate. This study also found that grafting failure was occurred when the stem diameters of both scions and rootstocks were thin. Therefore, it was suggested to use at least one stem with thicker than the average stem diameter. Field survey on the cutting angle of stems by hand were ranged from 13 to 55 degree for scions and 15 to 67 degree for rootstocks, respectively, which indicates that this could cause the grafting failure problem. However, the automatic grafting robot developed in this study rotates the seedlings 90 degree and then the stems are cut using a cutting blade. The control part of robot use all images taken from grafting process to determine the distance between a center of both ends of stem and a gripper center and then control the rotation angle of a gripper. Overall, this study found that The performance of automatic grafting robot using image recognition technique was superior with the grafting success rates of cucumber and tomato as $96{\pm}3.2%$ and $95{\pm}4%$, respectively.

• Journal of the Korean Applied Science and Technology
• /
• v.41 no.3
• /
• pp.813-824
• /
• 2024

This study was conducted to evaluate the long-term effects of training on the physical development and exercise performance of adolescent weightlifters, aiming to provide effective training and management strategies for improving competitive performance. In order to achieve the objectives of the study, adolescent weightlifters from middle and high schools in Chungcheongnam-do province [male middle school-aged athletes, n=5; female middle school-aged athletes, n=5; male high school-aged athletes, n=12; female high school-aged athletes, n=8] were examined over approximately 10 months of weightlifting-based training to analyse the changes in body composition, physical fitness (muscular strength, muscular endurance, agility, flexibility, dynamic balance, coordination), and isokinetic muscular function (trunk and lower extremity). As a result, it was found that the physical development of middle and high school-aged athletes underwent physical development primarily characterized by an increase in lean body mass. Additionally, back muscle strength and power, which contribute to rapid and efficient force transmission between the upper and lower body, as well as grip strength necessary for controlling the barbell with a stable grip, are significant factors. These aspects were notably enhanced through specialized training and competitive experience for weightlifting performance at the high school level. On the other hand, changes in factors beyond the primary physical attributes contributing to weightlifting performance were limited, suggesting differences in effectiveness likely stemming from the specific composition of training programs or the athletes' experience and skill levels. Collectively, the findings from this study, which evaluates the physical characteristics and exercise abilities of adolescent weightlifters, are expected to contribute to improved competitive performance of weightlifters.