• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.627-629
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• 2004

V type suspension string sets prevent instabilities from swing motion by the horizontal angle and by wind pressure. These installation conditions are controled mainly 3 items - normal swing angle by horizontal angle of line, unusual swing angle by strong wind, minimum vertical loads. We calculated and analysed that factors for the 765kV transmission line condition. And we were tested swing characteristics of V-string sets in real size test situation. So, we find to installation condition for the V type suspension string sets. This results will be used to design of V type suspension string set and to decision of the installation condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1761-1766
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• 2008

This paper deals with a novel autocalibration method of three-axis micromachined accelerometers applied to a new golf swing diagnosis equipment for golfers. This diagnosis equipment can help golfers monitor and anlalyze their swing posture and therefore modify their swing action to get better score and enjoy their lives through golf. The micromachined accelerometers to get information of the motion are the essential part of the putting club to measure the three-axis acceleration as accurately as possible. This paper presents an efficient autocalibration algorithm to find the offset and sensitivity of accelerometers by only using the static measurement data at six different positions. The experimetnal results on the developed putters show the validity of the proposed algorithm for the new smart putter.

• 한국운동역학회지
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• 제17권4호
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• pp.115-125
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• 2007

Grould Reaction force(GRF) is important in human movements and GRF measurements are one of the most frequently used tool in biomechanical studies. In the studies of the golf swing motion, people refer to GRF as weight transfer. A successful golf swing motion requires many segments activation sequences which are controled by the nerve system. Due to the inter- and intra-individual variability of the human movement and the movement strategies, reliability of the measurements are important in human movement studies. Previous golf researches were based on group studies and certain events' values were analyzed. The purposes of this study were to determine the number of trials for the reliable golf swing GRF data collection, to reveal the variability level of the meaningful components of the golf swing GRF, and to classify the types of the golf swing GRF patterns. Twenty three male professional golfers($26.4{\pm}6.6$ years, $174.3{\pm}5.2\;cm$, $71.3{\pm}6.5\;kg$) signed an informed consent form prior to participation in this study. GRFs of driver swings were collected with Kistler 9285 force platform and 9865A amplifier, and calculated by the KwonGRF program(Visol, Korea). Sampling frequency was 1080 Hz. GRF data were trimmed from 1.5 s prior to the impact to 0.5 s after the impact. The number of trials for the reliable GRF collection was determined when the change in floating mean overs the 25 % of the standard deviation of that variable. Variabilities of the variables were determined by the coefficient of variation(CV) of 10 %. The types of GRF patterns were determined by visual inspection of the peak GRF shapes. The minimum number of trials for the reliable golf swing GRF data collection was five. Ten-trial seems more conservative. The value of the peak GRF was more reliable than the value of the impact GRF. The CV of the peak GRF and impact GRF were 7.4 %, 15.2 %, respectively. Because of the +/- sigh of the peak GRF appearance time, it was impossible to calculate CV of the peak GRF appearance time. Golf swing GRF patterns were classified as sing peak type, double peak type, and plateau peak type. This classification suggests the presence of the different golf swing weight transfer strategies.

• 한국운동역학회지
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• 제31권4호
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• pp.308-313
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• 2021

Objective: The purpose of this study was to investigate the effect of different kettlebell mass (30%, 40%, and 50% of the body mass) on kinematics and kinetic variables of kettlebell swing. Method: Total of 16 healthy male who had at least 1 year of kettlebell training experience were participated in this study (age: 31.69 ± 3.46 yrd., height: 173.38 ± 4.84 cm, body mass: 74.53 ± 6.45 kg). In this study, a 13-segments whole-body model (upper trunk, lower trunk, pelvis, both side of forearm, upperarm, thigh, and shank) was used and 26 reflective markers were attached to the body to identify the segments during the movement. A 3-dimensional motion analysis with 8 infrared cameras and 4 channeled EMG was performed to find the effect of kettlebell mass on its swing. To verify the kettlebell mass effect, a one-way ANOVA with a repeated measure was used and the statistical significance level was set at 𝛼=.05. Results: Firstly, in all lower extremity joints and thoracic vertebrae, a statistically significant change in angle was shown according to an increase in kettlebell mass during kettlebell swing (p<.05). Secondly, in both the up-swing and down-swing phases, the knee joint and ankle joint ROM showed a statistically significant increase as the kettlebell mass increased (p<.05) but no statistically significant difference was found in the hip joint and thoracic spine (p>.05). Lastly, the hamstrings muscle activity was statistically significantly increased as the kettlebell mass increased during up-swing phases (p<.05). Also, as the kettlebell mass increased in P4 of the down swing phase, the gluteus maximus showed a statistically significantly increased muscle activation, whereas the rectus femoris showed a statistically significantly decreased muscle activation (p <.05). Conclusion: As a result of this study, hip extension decreased and knee extension increased at 40% and 50% of body mass, and the spine also failed to maintain neutrality and increased flexion. Also, when kettlebell swings are performed with 50% of body mass, synergistic muscle dominance appears over 30% and 40% of body mass, which is judged to have a risk of potential injury. Therefore, it is thought that for beginners who start kettlebell exercise, swing practice should be performed with 30% of body mass. In addition, even in the case of experienced seniors, as the weight increases, the potential injury risk may increase, so it is thought that caution should be exercised when performing swings with 40% and 50% of body mass. In conclusion, it is thought that increasing the weight after sufficiently training with 30% of the weight of all subjects performing kettlebell swing is a way to maximize the exercise effect as well as prevent injury.

• 한국운동역학회지
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• 제14권3호
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• pp.177-189
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• 2004

Kinematic and kinetic analysis using 3D Motion Capture system are common, yet there is little in the literature that discuss the relationship and coactivity between muscles during the golf swing. The purpose of this study was to describe the relationship between the employed 16 muscles during golf swing. We could observe 3 muscle patterns such as 'Line' shape, 'L' shape, and 'Loop' shape for the golf swing activity. The 'Line' shape indicates that two muscles act almost perfectly in phase, and the 'L' shape represents that two muscles act in a reciprocating manner(When one is active, the other is quiescent and vice versa). And the 'Loop' shape indicates that two muscles act sequently(After one is active, the other act). In these results, we knew the muscle patterns during golf swing is similar to the patterns during gait. And we presented it was possible to show the consistence of golf swing through the frequency analysis of muscle patterns. We believe that the results potentially useful for the golf players and coaches to analyze their performance.

• 대한기계학회논문집A
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• 제21권10호
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• pp.1683-1693
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• 1997

In this paper, a new nonlinear dynamic model is derived for a 2-dimensional overhead crane based on a new definition of 2-degree-of-freedom swing angle, and a new anti-swing control law is proposed for the crane. The dynamic model and control law take simultaneous travel and traverse motions of the crane into consideration. The model is first linearized for small motions of the crane load about the vertical stable equilibrium. Then the model becomes decoupled and symmetric with respect to the travel and traverse axes of the crane. From this result, a decoupled anti-swing control law is proposed based on the linearized model via the loop shaping and root locus methods. This decoupled method guarantees not only fast damping of load-swing but also zero steady state position error with optimal transient response for the 2-dimensional motion of the crane. Finally, the proposed control method is evaluated by controlling the simultaneous travel and traverse motions of a 2-dimensional prototype overhead crane. The effectiveness of the proposed control method is then proven by the experimental results.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.315-320
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• 2004

Swing check valves are the most common type of check valve in nuclear power plant and need to be operated property to perform their functions and to keep the valve internals stable. However, for a swing check valve disc to remain stable, the opening characteristics should be identified and the upstream flow velocity should be enough to hold the disc fully open and without motion. Thus it is necessary to develop a model for predicting the flow velocity for a given disc opening. In the present study, the disc positions with mean flow velocity were measured for 3 inch and 6 inch swing check valves. Comparison of the measurements with the existing models showed that the models underestimate the mean flow velocity for a given disc position. Therefore, the existing model for predicting swing check valve disc position was improved with the realistic disc impingement area perpendicular to the flow stream and the experimental data. The result showed that the improved model with the best estimate of kb = 0.04 predicts well the disc openings of 6 inch swing check valve, especially in the low velocity region. For better prediction of the disc opening at high flow velocity, however, it is recommended to develop a kb correlation with the disc angle.

• The Journal of Korean Physical Therapy
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• 제29권1호
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• pp.33-38
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• 2017

Purpose: This study was conducted to investigate the effects of variations in arm swing during gait on movement of the trunk and pelvis. During the gait task, the angle of the trunk and pelvic rotation were analyzed according to arm swing conditions. Methods: Seventeen healthy males participated in this study. All subjects were analyzed for gait on a treadmill three times each under three different types of arm swing conditions - natural arm swing, restricted arm swing using a phone, restricted swing in both arms. 3-D motion analysis systems were used to collect and analyze the kinematic data of trunk and pelvic movements, and repeated one-way ANOVA was used to compare the trunk and pelvic kinematic data and symmetry index. The level of significance was ${\alpha}=0.05$. Results: The results showed kinematic differences in trunk and pelvic during gait based on the arm swing conditions. Specifically, there were significant differences in trunk rotation, left and right trunk rotation and symmetry index of trunk rotation during gait among the three arm swing conditions. ROM was used to calculate a symmetry index (SI) based on the average left and right trunk rotation in which a value closer to zero indicated better balance. The SI obtained for arm swing restricted with the phone was closer to -1 than the other conditions. Conclusion: Restricted arm swing due to use of a phone had the possibility to induce instability of postural control while walking, which could be seen to suggest a risk of falling during gait.

• 복식문화연구
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• 제22권4호
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• pp.632-639
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• 2014

The purpose of this study was to verify the effect of drive swing on multiple functional wear wearing in golf. The subjects were 6 men ($22.67{\pm}0.82$ yrs, $175.42{\pm}3.42cm$, $78.75{\pm}4.78kg$), who had career each with at least 8 yers golf experience with right-hander. For kinemetical analysis, this study used equipments with 7 motion capture cameras (300Hz) and analysis program (Nexus1.5). The total time of the club head, displacement magnitude of the COM and swing plane were compared of according to functional wear wearing and non-weraing during golf drive swing. The results of the study are as follows. The total time of the club on wearing ($2.18{\pm}0.06sec$) was faster than non-wearing ($2.52{\pm}0.15sec$). Displacement magnitude of the COM on wearing ($4.06{\pm}0.67cm$) was shorter than non-wearing ($5.79{\pm}0.72cm$). Also, swing plane was found to be significantly different of 3 phase excepted BST-DS (back swing top-down swing) phase. AD-BST (address-back swing top) phase on wearing ($13.86{\pm}3.08cm$) decrease more than non-wearing ($20.82{\pm}3.99cm$), DS-IP (down swing-impact) phase on wearing ($6.25{\pm}1.35cm$) decrease more than non-wearing ($7.18{\pm}1.52cm$) and IP-FT (impact-follow though) phase on wearing ($7.93{\pm}2.09cm$) decrease more than non-wearing($9.68{\pm}2.02cm$). The multiple functional wear wearing was contribution to come close for one-plane, a long with consistency and accuracy on golf drive swing.

• 한국운동역학회지
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• 제19권1호
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• pp.167-177
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• 2009

본 연구의 목적은 골프화 개발에 있어 골프화 종류에 따른 기능성 검증을 위해 골프 스윙 시 골프화 종류별 3차원 동작분석을 통하여 골프화가 골프 스윙에 미치는 영향을 알아보고자 한다. 연구대상은 골프 프로 자격증을 소지한 경력 10년 이상인 프로골퍼 5명으로 착용 골프화 사이즈가 270mm이었다. 스윙 동작 분석을 위해 Motion Analysis사(Santa Rosa CL USA)의 3차원 동작분석 시스템 및 EVaRT 4.2 소프트웨어를 사용하여 변인 값들을 분석하였다. 드라이버 스윙동작 중 어드레스(El), 탑(E2), 임팩트(E3), 피니쉬(E4)시의 각 이벤트 간의 구간(P1, P2, P3) 변인 값을 분석하여 스윙 구간별 시간, 최대속도, 신체이동 속도, 양발 분절의 속도, 발목의 뒤틀림 각도에 대한 조사를 실시하여 골프화의 종류와 수행능력의 연관성에 대하여 알아보았다. 실험결과 골프화 Type C의 경우 어드레스에서 탑까지의 시간이 가장 짧게 나타나 어드레스 시 안정성을 향상시켜 줄 것으로 사료된다. 또한 좌우 골프화의 최대 속도 신체중심 이동 최대 속도 좌우 발의 최대 속도의 경우도 골프화 Type C의 속도가 가장 빠르게 나타났으며 신체의 중심을 빠르게 하고 발의 회전력을 증가시켜 임팩트 시 다른 골프화보다 큰 힘을 전달할 수 있을 것으로 사료된다.