• 한국운동역학회지
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• 제20권4호
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• pp.457-467
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• 2010

This study intends to analyze the projection factors' difference on each record of women's javelin throwing. For this purpose, the research analyzed the best record and the lowest one of athletes in top 1~7 ranks respectively, who participated in 2009 Daegu Pre-Championship Meeting. For analyze kinematic factors, we analyzed their game photos mainly shot by 3 cameras installed in side places. The used analysis program was Kwon3D 3.1. Analysis variables were the projection velocity, angle, height, trunk lean angle, and supporting leg's knee angle. The results concluded as follows: Different record showed statistically significant differences(p<.05) in terms of horizontal velocity and resultant velocity. There were no statistically significant differences in the variables of projection angle, its height, trunk lean angle and knee angle of support leg. But for the analyzed results to each individual characteristics, the horizontal velocity, projection height, knee angle of support leg and trunk lean angle of release event appeared to have influence on record.

• 한국추진공학회지
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• 제15권2호
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• pp.36-43
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• 2011

본 논문에서는 스윕과 린의 각도에 따른 부분흡입형 초음속 터빈의 성능 특성을 분석하기 위하여 유동해석을 실시하였다. 유동해석은 스윕과 린의 3가지 각도($5^{\circ}$, $10^{\circ}$, $15^{\circ}$)에 대해 수행되었다. 해석결과, 전반적으로 스윕 각도에 커질수록 효율이 증가하였다. 다만, 스윕 각도가 $5^{\circ}$일 때에는 기본익형보다 효율이 더 떨어졌다. 린 각도가 커질수록 전압력 손실은 줄어들었지만 정효율은 감소하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.786-792
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• 2010

본 논문에서는 스윕과 린의 각도에 따른 부분흡입형 초음속 터빈의 성능 특성을 분석하기 위하여 유동해석을 실시하였다. 유동해석은 스윕과 린의 3가지 각도($5^{\circ}$, $10^{\circ}$, $15^{\circ}$)에 대해 수행되었다. 해석결과, 전반적으로 스윕 각도에 커질수록 효율이 증가하였다. 다만, 스윕 각도가 $5^{\circ}$일 때에는 기본익형보다 효율이 더 떨어졌다. 린 각도가 커질수록 전압력 손실은 줄어들었지만 정효율은 감소하였다.

• 한국전문물리치료학회지
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• 제30권1호
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• pp.8-14
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• 2023

Background: Excessive hamstring (HS) activation due to the weakness of the gluteus maximus (GM) causes pain in the hip joint. A single-leg deadlift is a hip extensor exercise, especially GM, that includes functional movements in daily life and complex multi-joint training. In single-leg deadlift, the muscle activity depends on the forward trunk lean angle, and it's necessary to study which muscles are used dominantly depending on the angle. Objects: The purpose of this study was to compare the effect on the muscle activity of the GM and HS during single-leg deadlift according to different forward trunk lean angles and the ratio of the GM vs HS (GM/HS). Methods: Twenty-one healthy female participants were recruited. The muscles activities of the GM, HS and the GM/HS ratio were measured through electromyography during single-leg deadlift according to three condition of forward trunk lean angles (30°, 60°, and 90°). Results: The GM and HS activities significantly differed among three conditions (p < 0.05). GM/HS ratio was significantly higher at 30° and 60° of forward trunk lean compared to 90°. Moreover, the GM activity was significantly higher at 60° of forward trunk lean than at 30° (p < 0.05). Conclusion: The single-leg deadlift at 60° of forward trunk lean is a proper GM muscle strengthening exercise.

• 한국운동역학회지
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• 제30권1호
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• pp.51-61
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• 2020

Objective: The purpose of this study is to analyse and comparison the differences of kinematic variables for Fente skill in Fencing. Method: For this, 15 people were selected as 5 beginners with less than 2 years of experience, 5 intermediate-class people with more than 2 years and less than 4 years, and 5 experts-class people with more than 4 years. Through the comparison of Marche Fente motion according to proficiency, for the necessary time, travel distance, the kinematical factor of joint angle, oneway ANOVA was performed in order to identify differences according to variables by phase. Results: The time required for each phase was shown to be shorter for all phases experts than for beginners and intermediates. At the horizontal displacement of the foot, the right foot left out the last phase and the experts appeared long. The left foot showed short beginners in all phases. The angle of forward lean showed that the angle of forward lean was tilted forward by the experts of all phases. There was a difference between the left and right joint angles of the lower limb, both of the ankle, knee and hip joints. Conclusion: In overall, Beginners should quickly widen the distance of their feet when they make a Fente movement. The beginner shall tilt the upper body forward in order to increase the angle of forward lean. The beginner shall, in the last phase, have a smaller angle on the hip joint.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.858-863
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• 2001

In this paper, the test and result of flow and combustion for 21AFR lean fuel models are described. The necessity to develop the low emission combustor has been issued from the concern on the increase of green house and the destruction of ozone layer. To evaluate the flow and combustion performance of new designed 21AFR lean modules, the hydraulic tests in stereo lithographic airflows models, the low pressure combustion tests in three injectors model for weak extinction and ignition and the high pressure combustion tests in single sector for NOx, SAE and efficiency are performed. The low pressure tests reveal that the governing parameters in weak extinction and ignition at atmospheric condition are prefilmer length, swirl flow rotation direction, secondary swirl angle and flow split. As a results of combustion test at high pressure, the efficiency and smoke level are satisfied with performance targets, but EINOx of 17.8 is higher than target value of 13.1. The high pressure tests show that the main parameters influenced on NOx are primary swirl angle, swirl flow rotation direction, heatshield exit angle and liner mixing hole location.

• 대한기계학회논문집B
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• 제26권8호
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• pp.1132-1137
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• 2002

In this paper, the test results of the combustion for 2 IAFR lean fuel models are described. The need for the low emission combustor has been issued from the concern on the increase of green house and the destruction of ozone layer. To evaluate the flow and combustion performance of newly designed 21AFR lean modules, the hydraulic tests in stereolithographic airflows models, the low pressure combustion tests in three injectors model for weak extinction and ignition and the high pressure combustion tests in single sector for NOx, SAE and efficiency are performed. The low pressure tests reveal that the governing parameters in weak extinction and ignition at atmospheric condition are prefilmer length, swirl flow rotation direction, secondary swirl angle and flow split. As a result of combustion test at high pressure, the efficiency and smoke level are satisfied with performance targets, but EINOx of 17.8 is higher than target value of 13.1 The high pressure tests show that the main parameters influenced on NOx are primary swirl angle, swirl flow rotation direction, heatshield exit angle and liner mixing hole location.

• 한국운동역학회지
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• 제14권1호
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• pp.51-63
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• 2004

The purpose of this study was to investigate a three dimensional kinematic variables about the last stride and the release phase of the throwing technique for female javelin throwers. For the motion analysis, Six female javelin throwers were used as subjects. Three-dimensional coordinates were collected using the Kwon3D Motion Analysis Package Version 2.1 Program. Two S-VHS Video Cameras were used to record the locations and orientations of control object and the performances of the subjects at a frequency of 6.0 HZ. After the kinematic variables such as the time, the distance, the velocity, and the angle were analyzed about the last stride and release phase, the followings were achieved; 1. For the effectively javelin throwing, the subjects appeared to do long the approach time in the phasel of landing phase, and short the delivery time in release phase 2. In the release event, the other subjects except for subject A appeared to throwing in the lower condition than the height of themselves. This result showed to slow the projecion velocity. 3. For increase the projection vcelocity of the upper extremity joint in the release event, it appeared to do extend rather the shoulder angle than increase the extension of elbow joint. 4. The body of COG angle showed to gradually increase nearly at the vertical axis in the release event. But the front lean angle of trunk showed a small angle compare to increase of the body of COG angle. Therefore for the effectively momentum transmission of the whole body in the javelin, the front and back lean angle of trunk appeared to do fastly transfer the angle displacement in the arch posture or the crescent condition during the deliverly motion of the release phase.

• 한국운동역학회지
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• 제14권3호
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• pp.149-163
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• 2004

This study analyzed kinematic variables about the cross step, the delivery and the release for women's javelin athletics recorded over 50m in the 2004 Busan International Athletics Competition. It was used the Kwon3D Motion Analysis Package Ver. 3.1 Program(Kwon, 2000) for analysing the kinematic variables about the distance, the velocity, and the angle, then we had the results as follows; 1 In the Cross step phase, the COG velocity was low because their step length was short. To keep the CM velocity from the approach to the last cross over step contact, the athletes have to keep the longer step length within about 130% of the athletics' height. 2. In the Delivery phase, the athletics' COG height was gradually lower, and the deceleration of the COG was going up. As the same in the cross step, Therefore the athletes have to increase the step length within about 100% of their height, in order to increasing the COG velocity. And it was shown they have to make small angle of the elbow as possible from the right foot contact to the left foot contact in order to being the big acceleration of the upperarm at the release phase. 3. In the release phase, it was shown to being low position of the release point as the COG was low and then the release velocity of the upperarm was low. Specially when the shoulder lean lateral angle is big at the release phase, it was shown they have a excessive release angle. And, when it was shown the high rotation angle of the shoulder, the shoulder was opened forward bigger than the trunk was opened forward. So the transmission of velocity from the proximal segments was a fast change.

• 한국운동역학회지
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• 제14권2호
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• pp.15-26
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• 2004

The purpose of this study was to investigate the kinematic variables of peters motion in parallel bars. The subjects were 3 male national gymnasts. For this study, kinematic data were collected using video camera. Coordinate data were low-pass filtered using a fourth-order Butterworth with cutoff frequency of 6Hz. Each valuables analyzed was used to compare kinematic features between the subjects. The conclusions were as follows; 1. For a stable regrasp motion, the subjects appeared to increase horizontal and vertical displacement during the DS phase because it induce a vertical elastic of body and reaction of bar for the US phase. 2. For a stable hand standing motion of the regrasp, the subjects appeared to maintain the fast vertical and horizontal velocity during the DS phase, but in contrary during the US and Air phase the vertical and horizontal velocity appeared to do decrease. 3. When the arm lean angle and the trunk lean angle maintain a big angle during the DS phase, the subjects appeared to do a stable performance to release in a high position.