• 한국컴퓨터정보학회논문지
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• 제28권1호
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• pp.137-142
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• 2023

본 연구에서는 초등학교 야구선수의 타격 속도와 균형 능력의 상관관계를 규명을 제안한다. 본 연구의 대상자는 40명이었다. 타격 속도는 zepp2baseball을 이용하여 측정하였고, 균형 능력은 biorescue를 이용하여 측정하였다. 균형능력의 측정은 눈 뜬 상태에서 이동 면적·눈 뜬 상태에서 이동거리·눈 뜬 상태에서 평균 이동속도·눈 감은 상태에서의 이동 면적·눈 감은 상태에서의 이동거리·눈 감은 상태에서의 평균 이동속도를 측정하였다. 타격 속도와 균형 능력 간의 상관관계를 분석하기 위해 피어슨 상관분석을 이용하였다. 타격 속도와 눈 감은 상태에서의 이동면적 사이에는 유의한 음의 상관관계가 있었습니다(r=-0.366, p<0.05). 타격 속도와 눈 감은 상태에서의 이동길이 사이에는 유의한 음의 상관관계가 있었다(r=-0.348, p<0.05). 타격 속도와 눈 감은 상태에서 평균 이동속도 사이에는 유의한 음의 상관관계가 있었다(r=-0.455, p<0.01). 그 중 눈 감은 상태에서 평균 이동속도가 가장 높은 상관관계를 보였다(p<0.01). 이러한 결과는 균형능력의 향상이 타격 속도에 긍정적인 영향을 미친다는 것을 시사한다.

• 한국운동역학회지
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• 제23권2호
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• pp.91-97
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• 2013

The purpose of this study was to compare the effect of a new warm-up condition, overloaded arm weights (721 g each arm, [OA]), on the bat speed during warm-up and immediately after warm-up with traditional warm-up conditions such as no-extra mass warm-up (control condition, [CO]) and overloaded bat warm-up (885 g donut on a bat, [OB]) conditions. Twenty male subjects who had competitive baseball experience participated in this study. Electromagnetic motion capture system was used to capture body segment motions. Results indicated that the OB showed significantly slower bat speed than the CO and OA did during warm-up (p<.05) and the bat speeds of OA and OB were similar. There was no main effect of different types of warm-up condition on the bat speed at post-warm-up swings. However, the first trial immediately after the OA and OB showed significant slower than the later trials (p<.05). Conclusively, the overloaded arm weights and overloaded bat did not show statistical superiority than the standard warm-up conditions in the deck circle and recovery time more than 3 minutes after loaded warm-up is recommended.

• 한국운동역학회지
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• 제28권2호
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• pp.87-92
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• 2018

Objective: The purpose of this study was to investigate the factors affecting two kinds of bat swing behavior through kinematic analysis. Method: A total of 32 high school baseball players participated in this study. The ball was placed on the tee-ball in a position where the subject could easily swing and the standard bat swing was performed as quickly and as accurately as possible using aluminum bats and wooden bats. Results: The aluminum bat showed a rapid swing speed of about 1.79 m/sec compared to the wooden bat. The speed of the batted ball was found to be significantly greater for the aluminum bat than for the wooden bat. In addition, although the difference between the shoulder-pelvis rotation angle according to the type of bat was not indicated, there was a statistically significant difference between the aluminum bat and the wooden bat in terms of the rotational angular velocity. Conclusion: Even though the results can explain the difference between the bat swing speed and the speed of the batted ball depending on the bat's material, it is difficult to explain the difference depending on the type of bat at the shoulder-pelvis rotation angle. However, shoulder-pelvic rotation angular velocity appears to be higher for the aluminum bat, and the differences in the type of bat is considered to be related to the batting swing factor.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.239-244
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• 2019

본 연구는 초등학교 야구선수에 상지 근력과 배트 스윙 속도 간의 상관관계 분석을 알아보고자 하였다. 연구대상자 32명을 대상으로 실시하였다. 상지 근력은 양쪽 어깨 관절에 폄근 굽힘근 모음근 벌림근, 양쪽 팔꿉관절에 폄근 굽힘근의 근력과 배트 스윙 속도를 측정하였다. 상지 근력과 배트 스윙 속도의 상관관계를 알아보기 위해 pearson's cerrelation analysis를 사용하여 분석하였다. 우세 측 상지 근력과 배트 스윙 속도 간의 상관관계에서는 어깨 관절 모음근, 어깨 관절 벌림근, 팔꿉 관절 굽힘근, 그리고 어깨 관절 굽힘근 순으로 유의한 양의 상관관계를 보였으며, 비 우세측 상지 근력과 배트 스윙 속도 간의 상관관계에서는 어깨 관절 모음근, 팔꿉 관절 굽힘근, 어깨 관절 벌림근, 어깨 관절 폄근, 팔꿉 관절 폄근 그리고 어깨 관절 굽힘근 순으로 유의한 양의 상관관계를 보였다. 이와 같은 결과로 볼 때 상지근력이 강할수록 배트 스윙 속도가 증가하는 양의 상관관계를 나타내는 것을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1348-1375
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• 2018

Support Vector Machine (SVM) is a well-known machine learning classification algorithm, which has been widely applied to many data mining problems, with good accuracy. However, SVM classification speed decreases with increase in dataset size. Some applications, like video surveillance and intrusion detection, requires a classifier to be trained very quickly, and on large datasets. Hence, this paper introduces two filter-based instance selection techniques for optimizing SVM training speed. Fast classification is often achieved at the expense of classification accuracy, and some applications, such as phishing and spam email classifiers, are very sensitive to slight drop in classification accuracy. Hence, this paper also introduces two wrapper-based instance selection techniques for improving SVM predictive accuracy and training speed. The wrapper and filter based techniques are inspired by Cuckoo Search Algorithm and Bat Algorithm. The proposed techniques are validated on three popular e-fraud types: credit card fraud, spam email and phishing email. In addition, the proposed techniques are validated on 20 other datasets provided by UCI data repository. Moreover, statistical analysis is performed and experimental results reveals that the filter-based and wrapper-based techniques significantly improved SVM classification speed. Also, results reveal that the wrapper-based techniques improved SVM predictive accuracy in most cases.

• 한국철도학회논문집
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• 제18권3호
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• pp.241-251
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• 2015

유도상 아스팔트 콘크리트 궤도(이하, 유도상 AC궤도)는 아스팔트 콘크리트 노반(이하, AC노반)의 존재에 의해 유도상 궤도에 비해 열차하중 분산효과에 의한 강화노반 두께 감소가 가능하며 누적 소성 변위도 작을 뿐만 아니라 유지관리 측면에서도 유리한 궤도 구조이기 때문에 국외에서 적용 사례가 증가하고 있다. 그러므로 유도상 AC궤도의 국내 도입을 검토하기 위해 선행 연구를 통해 수행한 AC노반 유무에 따른 거동 특성을 분석하여 현재 설계기준에 명시된 유도상 궤도의 단면과 유사한 성능을 보이는 유도상 AC궤도의 단면을 분석한 바 있으며, 실대형 정 동적 열차하중 재하 실험 결과와의 비교를 통해 해석 결과의 신뢰성을 검증하였다. 본 연구에서는 선행 연구를 바탕으로 AC노반의 두께를 일정하게 하고 강화노반 두께를 변화시켰을 때에 획득된 AC노반 하면에서의 변형률을 이용하여 설계 수명을 산정하였고 각각의 단면에 대한 확률론적 LCC분석을 통해 기대 설계 수명을 만족하면서 기존 유도상 궤도와 비교하여 동등 또는 동등이상의 성능을 갖는 유도상 AC궤도의 설계 단면을 제시하였다.

• 한국운동역학회지
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• 제26권2호
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• pp.205-211
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• 2016

Purpose: The aim of this study was to analyze biomechanical factors and PMT (premotor time) of body muscles between elite college and amateur baseball players during the baseball batting motion. Method: Kinematic and electromyographic data were obtained for 10 elite college baseball players and 10 amateur baseball players who participated in this study. All motion capture data were collected at 200 Hz using 8 VICON cameras and the PMT of muscles was recorded using a Delsys Trigno wireless system. The peak mean bat speed and the peak mean angular velocities of trunk, pelvis, and bat with PMT of 16 body muscles were computed. These kinematic and PMT data of both groups were compared by independent t-tests (p < .05). Results: The pelvis, trunk, and bat showed a sequence of angular velocity value during baseball batting. The PMTs of right tibialis anterior, left gastrocnemius, external oblique, and erector spinae were significantly different between the two groups. Conclusion: The PMT of body muscles was related to the shifting of body and rotation of the pelvis and the trunk segment, and this action can be considered the coordinated muscle activity of the lower and upper body.

• 한국운동역학회지
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• 제22권3호
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• pp.277-284
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• 2012

The purpose of this study was to find out the changes in beginners' batting movements after taking undergraduate baseball lectures, by comparing and analyzing the speed of bat, the angle of body and its segments, the angular velocity and so on. For this purpose, the author picked up five undergraduates who had not taken baseball lectures, and conducted three-dimension computerized tomography twice on them, that is, before and after taking baseball classes, with eight infrared cameras and two force platforms. The conclusions are, first, the time required for swing was shortened after taking the classes. Second, the maximum velocity of the bat-end was increased. Third, at the time of impact, while the rotation angles of the pelvis and the tip of left foot were increased, the left elbow had more flexion after the classes. Fourth, the size of ground reaction force was increased at the point of swing where the ground reaction force of left foot became maximized. As we can infer from these conclusions, beginners' hitting movements before taking baseball classes tended to swing only with the arms, without waist rotation and weight shift of the lower body, but after the classes, their movements were proved to be corrected into the swing using the lower body. For the future studies, the author expects a research in a close to real environment by using pitching machine.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.1827-1832
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• 2014

4세대 이동통신시스템 '롱텀에볼루션(LTE)'의 핵심기술인 다중 송수신 (MIMO) 안테나 시스템은 추가적인 주파수나 송신전력의 할당 없이도 채널 용량을 안테나 수에 비례하여 증가시킬 수 있는 장점으로 인해 데이터 전송 속도를 획기적으로 늘리는 기술로 4세대 이동통신기술 진화의 핵심기술로 꼽히고 있다. 본 논문은 다중 송수신 안테나 시스템에서 사용되는 2개 이상의 DAC 대신에 고속 DAC와 아날로그 스위치를 각각 한 개씩 사용하여 기존 방식의 장점을 유지하며 설계비용 감소, 물리적 크기 축소화 등 경제적 효율을 증가시킬 수 있는 MIMO 시스템에서 데이터 컨버터를 줄일 수 있는 방안을 제안한다.

• 한국환경과학회지
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• 제26권6호
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• pp.779-788
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• 2017

In this study, we analyzed the changes in the echolocation and prey-capture behavior of the horseshoe bat Rhinolophus ferrumequinum from search phase to capture time. The experiment was conducted in an indoor free-flight room fitted with an ultra-high-speed camera. We found that the bats searched for food while hanging from a structure, and capturing was carried out using the flight membrane. In addition, it was confirmed that the mouth and uropatagium were continuously used in tandem during the capturing process. Furthermore, using Constant Frequency (CF), we confirmed that the prey catching method reflected the wing morphology and echolocation pattern of R. ferrumequinum. The echolocation analysis revealed that the pulse duration, pulse interval, peak frequency, start-FM-bandwidth, and CF duration decreased as the search phase approached the terminal phase. Detailed analysis of echolocation pulse showed that the end-FM bandwidth, which increases as it gets nearer to the capture time of prey, was closely related to the accurate grasp of the location of an insect. At the final moment of prey capture, the passive listening that stopped the divergence of the echolocation was identified; this was determined to be the process of minimizing the interruption from the echo of the echolocation call emitted from the bat itself and sound waves emitted from the prey.