비선형 진동계의 정규모드 계산 연구

이경현(Kyoung-Hyun Lee),한형석(Hyung-Suk Han),박성호(Sungho Park),전수홍(Suhong Jeon) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4

Nonlinear normal modes(NNMs) is a periodic solution of autonomous nonlinear dynamic systems. Periodic solution of nonlinear system can be calculated by numerical methods, starting from the linear normal modes near the fixed point. In this study iteration of the solution is presented by multiple shooting method and continuation is presented by pseudo-arclength continuation method. The stability of the NNMs are analyzed using Floquet multipliers, and bifurcation points are calculated using indirect method. Proposed analyses are applied to nonlinear spring-mass system.

여자 프로 농구선수들의 스포츠 수행전략과 자기관리 전략이 집단 응집력에 미치는 영향

이경현 ( Kyoung Hyun Lee ),하은주 ( Eun Ju Ha ),유경호 ( Kyoung Ho Yoo ) 한국스포츠심리학회 2014 한국스포츠심리학회지 Vol.25 No.2

Purpose: The aim of this study was to examine the influence of Self Management Strategies and Sports Performance Strategies for Team Cohesion on women``s pro basketball team. Methods: Data was collected by a survey method from 89 Korean women`s professional basketball athletes for this study. The data analysis was conducted suing the PASW statistics ver. 18.0 with the factor analysis, one-way ANOVA, and stepwise regression performed and Scheffe`s post-hoc was applied if when the results showed a significantly difference. Results: (1) group social cohesion, mental readiness, daily living management, physical conditioning, interpersonal relationship, condition control, and imagery-goal setting were significantly different by aging, (2) mental readiness, daily living management, physical conditioning, interpersonal relationship, training management, condition control, imagery-goal setting, and relaxation were significantly different by career, (3) group task cohesion, daily living management, physical conditioning, interpersonal relationship, and condition control were significantly different by average playing time, (4) no different by position, (5) Self Management Strategies (training management, daily living management, mental readiness) influenced Team Cohesion, and (6) condition control influenced Team Cohesion (individual social cohesion, individual task cohesion, group task cohesion). Conclusion: The women pro basketball players who have higher age, career, and average playing time than the others efforts harder with self management and sport performance strategies for maintaining and improving their athletic performance which influence to enhance team cohesion, and it finally supports team performance being advanced.

노화에 따른 감각-운동 적응 형태 차이 연구

이경현 ( Kyoung Hyun Lee ),이지항 ( Ji Hang Lee ),윤희철 ( Hee Chul Yoon ) 한국스포츠심리학회 2013 한국스포츠심리학회지 Vol.24 No.2

감각-운동 적응에 관련된 이론적 배경 및 신경 생리학적 특성은 이미 많은 선행 연구가 존재한다. 그러나 이들 연구는 주로 적응 행태 자체에 관심을 두고 그 기전과 관련 신경 작용에 연구적 노력을 집중해왔다. 최근에서야 이 같은 결과들을 근거로 일상생활에 적용 가능한 방법론 적인 조망이 이루어지고 있지만 아직은 현장에 직접 적용할 수 있을 수준의 연구적 노력이 미흡하다. 따라서 본 연구는 노인과 젊이의 감각-운동 적응 능력 차이를 알아보았다. 노화에 따른 실제 기능적 문제점을 도출하고 이를 정상화 할 수 있는 방안 도출의 근거자료를 제시하기 위함이었다. 이를 위해서 프리즘 적응 패러다임을 적용하였고 두 가지 시각 환경인 종말시각 피드백 환경에 노인 5명, 청년 8명, 동시시각 피드백 환경에 노인 5명, 청년 7명을 무선 배치했다. 실험 결과 종말시각 피드백에서는 청년 집단이 노인 집단에 비하여 적응속도를 나타내는 운동 수행 오차와 적응정도를 나타내는 후효과에서 유의하게 높게 나타났으며, 이와 같은 결과는 적응 속도 및 정도가 시행 간 오차 수정 시 발생하는 의도적(explicit) 전략의 영향을 받은 것으로 해석된다. 그러나 동시시각 피드백에서는 운동 수행 오차와 후효과 모두에서 집단 간 차이가 나타나지 않았다. 이러한 결과는 시행 중 적응이 발생하는 암묵적(implicit) 특징에 의한 것으로 해석 하였다. 이 같은 결과를 바탕으로 암묵적인 운동 적응 능력이 노화의 영향을 비교적 적게 받는다는 결과를 유추하고 이를 이용한 노인 운동 학습을 위한 맞춤형 환경 조성의 필요성을 제시했다. The purpose of this study was to investigate the changes in sensory-motor adaptation during the prism adaptation on aging. There were two visual environments (concurrent visual feedback and terminal visual feedback) which eliciting different mechanisms. Ten elderly and 15 young(control group) participants were divided into the two visual environment groups randomly. Five elderly and 8 young participants were assigned to the terminal visual feedback group, while Five elderly and 7 young participants were arranged the concurrent visual feedback group. The result showed that, in the concurrent visual feedback environment, there was no differences in the adaptation rate during the prism adaptation and after effect between the elderly group and young group. However, the adaptation rate and after effect of the young group were significantly higher than the elderly group in the terminal vision environment. Explicit trial to trial error correction strategy was suggested as a characteristic of the terminal visual feedback environment. On the other hand, the concurrent visual feedback environment elicited the characteristic of implicit learning during the adaptation. It was concluded that the elderly displayed adaptation deficiency when the cognitive intervention was required, while had no problem when the condition required an implicit adaptation. The importance of optimal environments for learning/adaptation among elderly were discussed.

대학 태권도 지도자의 자율성지지 코칭행동이 선수들의 경기력에 미치는 영향: 그릿의 매개효과

이경현 ( Lee Kyoung-hyun ),강현우 ( Kang Hyun-woo ) 한국체육학회 2019 한국체육학회지 Vol.58 No.6

이 연구는 대학 태권도 선수들의 자율성지지와 경기력의 관계를 검증하고 그릿의 매개효과를 검증하는데 그 목적이 있다. 이에 대학 태권도 겨루기 선수 317명을 비확률 표집방법의 목적적 표집방법으로 선정하여 자료를 수집하였다. 수집된 자료는 PASW 21.0, AMOS 21.0 프로그램을 이용하여 기술통계, 신뢰도분석, 상관분석, 확인적 요인분석, 구조방정식모형분석을 시행하였고, 매개효과의 유의성 검증을 위해 bootstrapping을 사용하였다. 그 결과 첫째, 대학 태권도 지도자의 자율성지지는 선수들의 경기력에 긍정적인 영향을 미치는 것으로 나타났다. 둘째, 자율성지지가 그릿에 긍정적인 영향을 미치는 것으로 나타났다. 셋째, 그릿은 경기력에 긍정적인 영향을 미치는 것으로 나타났다. 넷째, 그릿은 자율성지지와 경기력의 관계를 부분적으로 매개하는 것으로 나타났다. 이러한 결과를 바탕으로 태권도 지도자들이 현장에서 선수들을 지도하는데 있어 자율적 환경을 만들기 위한 세심한 계획과 노력이 필요할 것으로 판단된다. This study was processed for verification of the effect of autonomy supports on performance in university taekwondo players and investigation of mediating effect on grit. The data were collected in the university 318 players with purposive sampling of nonprobability sampling. The Collected data were analyzed by descriptive statistics, reliability analysis, correlation analysis, confirmatory factor analysis, structural equation model analysis using PASW 21.0 and AMOS 21.0 program, and bootstrapping was used to verify the significance of mediating effects. The study has gained the following results: First, the autonomy supports of the university taekwondo coach had positive effect on players performance. Second, the autonomy supports of the university taekwondo coach had positive effect on players grit. Third, grit of the university taekwondo players had positively affect performance. Fourth, grit of the players partially mediated the relationship between autonomy supports and performance. Based on these results, it is thought that careful planning and efforts are needed to create autonomy-supportive circumstances for the coaches to improve the performance of university taekwondo players.

프로 농구선수의 성취목표성향, 자기관리전략, 스포츠 수행전략, 집단 응집력의 구조적 관계

이경현(Lee, Kyoung-Hyun),이지항(Lee, Ji-Hang) 한국체육과학회 2015 한국체육과학회지 Vol.24 No.3

The purpose of this study was to identify the structural relationships among goal orientation, self management strategy, sports performance strategy, and team cohesion of professional basketball players. Two hundred one players initially completed the questionnaires for the study and responses from 185 participants were analyzed after initial screening process. For data analysis, frequency analysis, reliability analysis, correlation analysis, confirmatory factor analysis and structure equation model analysis were performed using the PASW 18.0 and the AMOS 18.0 programs. The results showed that the task goal orientation positively affected the self management strategy, the sports performance strategy, and the team cohesion. On the other hand, the ego goal orientation did not display any significant influence on the self management or the performance strategy. Also, there was a negative influence of the ego goal orientation on the team cohesion. The self management strategy positively affected the sports performance strategy and the team cohesion. However, the sports performance strategy showed no effects on the team cohesion. These results support the legitimacy of the hypothesized model by reflecting the characteristical influences of the task/ego goal orientations on athletes’ behavior.

노화에 따른 보행 중 제시된 인지적 이차 과제와 안정성 제어에 관한 연구

이경현(Lee, Kyoung-Hyun) 한국체육과학회 2017 한국체육과학회지 Vol.26 No.3

The aim of this study was to identify the ability of stability control while treadmill walking with three different walking speed condition([80%(slow), 100%(prefer), 120%(fast)] and cognitive secondary task on aging. The dependent variables were Braking Index(BI), step length, and step width as gait parameter for this study. 40 participants evenly assigned to two groups (old and young group) and each group divided into another two batches(provided cognitive dual-task or not). Using PASW statistics 18.0 program and Microsoft Office Excel 2007 software(descriptive statistics, three-was ANOVA test, and Scheffe"s post-hoc) were conducted for the collected data. The results showed that young group was higher than old group in BI and stop length, and fast walking speed was higher than the others in step length. In the Coefficient of Variation(CV) result, old group was higher than young group in BI and step length, and interaction effect significantly different between groups(old and young) and task(provided the test or not).

대학 태권도 선수들의 지도자신뢰와 경기력의 관계에서 스포츠맨십의 매개효과

이경현(Lee, Kyoung-Hyun) 한국체육과학회 2019 한국체육과학회지 Vol.28 No.6

This study was processed for verification of the effect of leader trust on performance in university taekwondo players and investigation of mediating effect on sportsmanship. The data were collected in the university 585 players with purposive sampling of nonprobability sampling. The collected data were analyzed by descriptive statistics, reliability analysis, correlation analysis, confirmatory factor analysis, structural equation model analysis using Excel 2010, PASW 21.0 and AMOS 21.0 program. The study has gained the following results: First, the leader trust had positive effect on players performance. Second, the leader trust had positive effect on sportsmanship. Third, sportsmanship had positively affect performance. Fourth, sportsmanship of the players partially mediated the relationship between leader trust and performance.

인지적 이차과제에 따른 보행 중 안정성 제어 연구

이경현(Lee, Kyoung-Hyun) 한국체육과학회 2013 한국체육과학회지 Vol.22 No.6

The aim of this study was to identify the ability of stability control with three different speed conditions (80%(slow), 100%(pref.), 120%(fast) of preferred speed) whether being provided cognitive secondary task or not during walking on a treadmill. Braking Index, step length, and step width as gait parameters were the dependent variables for this experiment. The experimental group was simultaneously asked generating words as the cognitive secondary task during walking with the different speeds and the control group wasn"t provided the dual task during walking. 10 participants(age: M±SD, 29.3±2.2) were assigned to the experimental group and 10 participants(age: M±SD, 29.7±2.l) were belonged to the other. The findings were significantly different when the collected data and coefficient of variation (CV) were put into two-way ANOVA and scheffe"s post-hoc. The results showed that fast speed was higher than slow speed in BI, and fast speed was higher than pref. and slow speeds in step length by walking speed but no difference with dual task and no interaction appeared. In the CV result, slow speed was higher than fast speed in BI and step length, and experimental group was higher than control group in BI. Also there was interaction with BI, which was argued in discussion.

함정 디젤엔진 진동규격 연구

이경현(Kyoung-Hyun Lee),한형석(Hyung-Suk Han),박미유(Mi-You Park),조흥기(Heung-Gi Cho) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10

Vibration of diesel engines in naval vessels causes structure vibration which is significant under water radiating noise source under CIS (Cavitation Inception Speed). So managing the vibration level of diesel engine is important for survivability and also durability of naval vessels. Therefore, in this research, a vibration criterion which is applied for Korean naval vessels are reviewed. It is compared with the DNV, ABS and merchant ship’s diesel engine criteria. And also vibration data of three Korean naval vessels are analyzed. As a result, reasonable criteria of diesel engine vibration and shipbuilding standards are suggested.

대학 축구동아리 참여자의 성취목표성향과 운동지속의 관계에서 운동만족의 매개효과 검증

이경현(Lee, Kyoung Hyun),최성주(Choi, Sung Joo),홍연지(Hong, Yeon Ji),장세용(Jang, Se yong) 한국체육교육학회 2015 한국체육교육학회지 Vol.19 No.4

본 연구는 대학교의 스포츠 동아리 중 규모가 가장 크다고 할 수 있는 종목인 축구 동아리에 참여하는 대학생을 대상으로 성취목표성향과 운동지속의 직접적인 관계를 확인함과 동시에 운동만족이 어떠한 매개효과를 미치는 지를 과학적으로 규명하는데 그 목적이 있다. 연구목적에 따라 대학 동아리 축구대회에 참가한 대학생들을 대상으로 총 314부의 설문을 실시하였으며, 회수한 질문지를 검토한 결과 문제점이 발견된 21부의 설문지를 제외한 총 293부의 설문지를 최종자료로 채택하였다. PASW 18.0 및 AMOS 18.0 프로그램을 이용하여 연구목적에 따라 각 측정변인들의 인과관계를 규명하기 위하여 구조방정식 모형을 사용하여 분석한 결과, 첫 번째로 과제목표성향은 운동만족과 운동지속에 정적인 영향을 미치는 것으로 나타났으며, 운동만족은 운동지속에 정적인 영향을 미치는 것으로 나타났다. 두 번째로는 과제목표성향과 운동지속의 관계에서 운동만족이 부분적인 매개효과를 미치는 것으로 나타났다. Purpose: The purpose of this study is to examine the direct relationship between the achievement goal orientation and exercise adherence that the members of university soccer clubs (one of large sports clubs in university) have, and to scientifically define the mediating effect of their exercise satisfaction. Method: To achieve the purpose, this study conducted a questionnaire survey with 314 university students who participated in university soccer club contest. Among the collected questionnaire copies, 21 copies with problems were excluded. As a result, 293 copies were finally used for analysis. For data analysis, PASW 18.0 and AMOS 18.0 programs were used. Result: To define and analyze the causal relationships between measured variables, this study employed structural equation model. According to the analysis, first, task goal orientation positively affected exercise satisfaction and exercise adherence, and exercise satisfaction positively influenced exercise adherence; secondly, exercise satisfaction gave partially mediating effect on the relationship between task goal orientation and exercise adherence. Conclusion: These results could interpret that the club member would participate the club physical activities consistently when the member most importantly considers the processing while training. Besides, the member could regard the activities as well as a part of own life.