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허성훈(Sunghoon Hur),김현수(Hyun Soo Kim),송현철(Hyun-Cheol Song) 한국세라믹학회 2021 세라미스트 Vol.24 No.3
Wireless energy transfer (WET) is the transmission of electric power without any physical connections such as wires. Currently, inductive coupling mediated by electromagnetic (EM) waves is the most common method of WET and is widely used to charge portable devices such as smartphones, Bluetooth earphones, electric shavers, and visual prostheses. However, its application is still limited due to a number of issues including low efficiency, short charging distance, heating problem, and limited choice of transmission medium. Due to these issues, EM-based WET cannot be applied to implantable medical devices, marine cable operation sensors, and electronic devices with electromagnetic interference shielding. Recently, as an alternative to EMbased WET, acoustic energy transfer mediated by sound waves becomes more attractive. Ultrasound offers advantages for transmission in dense media such as liquids or solids and is regardless of electromagnetic shielding. In this review, we investigate recent progress in acoustic power transfer technology in terms of acoustic energy conversion mechanism and provide the future research direction of acoustic power transfer technology.
동일 골격근량 적용 시 체지방량의 차이가 남성의 최대 근력에 미치는 효과
김성훈 ( Sunghoon Kim ),최종욱 ( Jonguk Choi ),허성훈 ( Sunghoon Hur ),이종삼 ( Jongsam Lee ) 대한스포츠의학회 2016 대한스포츠의학회지 Vol.34 No.2
We investigated that the relationship between body fat content and maximal muscle strength when skeletal muscle mass was matched. Muscle mass was measured from 140 preliminary selected people, and 30 males were finally selected and divided into one of four experimental groups: low body fat (group 1, ≤11.9%), low-moderate fat (group 2, 12.0%-16.9%), moderate-high fat (group 3, 17.0%-22.9%), high fat (group 4, ≥23.0%). All subjects undertook one repetition maximum (1RM) test of abdominal and back upper body`s and lower body`s, and bench press, squat, and back strength dynamometer was used. Repeated oneway analysis of variance and Tukey`s post-hoc test was adopted to specify mean differences among groups. Statistical significance level was set at α=0.05. 1RM of bench press was not different among groups (p>0.05) even though values from group 2 was marginally higher (15.9%) than group 1 values (p=0.091). 1RM of squat was higher in group 4 compared to group 2 and group 3 (p<0.05), and maximal back muscular strength was higher in group 1 and group 3 than group 2 (p<0.05). However, total 1RM values, sum of 1RM obtained from different exercises, did not reveal any statistical differences. No notable correlation was found between percent body fat (%BF) and maximal muscular strength. Interestingly, negative correlation of muscular strength was observed between %BF and relative (per kilogram) body mass (p<0.001), but not with between %BF and relative skeletal muscle mass. Therefore, it was concluded that maximal muscular strength is influenced not by fat mass but by skeletal muscle mass.
캐딜락 기구를 이용한 필라테스 전후방 팔 뻗기 동작이 체간 근 활성도에 미치는 효과
김진령 ( Jinryeong Kim ),허성훈 ( Sunghoon Hur ),안경준 ( Kyungjun An ),김송준 ( Songjune Kim ),이종삼 ( Jongsam Lee ) 대한스포츠의학회 2018 대한스포츠의학회지 Vol.36 No.4
Purpose: This study analyzed the muscle activity changes induced by motions of reaching forward and chest expansion that were examined from the bilateral muscles with rectus abdominis, external oblique, multifidus, and longissimus thoracic using Pilates cadillac instrument. Methods: Nine young adult women, who have no musculoskeletal disorder and any of chronic diseases, were participated. Surface electromyography system was used for recording of all signals produced by muscles, and then normalized as percentage of maximum voluntary isometric contraction (%MVIC). The paired t-test and repeated measures of analysis of variance was performed. Results: Reaching-forward motion showed a higher muscle activity from non-dominant external oblique muscle than that of the chest-expansion motion. During both reaching-forward motion and chest-expansion motion, MVIC values collected from dominant side of external oblique muscle were shown a significantly lower than the values obtained from non-dominant side (p<0.05). Conversely, %MVIC values in external oblique muscle collected from dominant side showed a significantly higher than the values obtained from non-dominant side of the same oblique muscle (p<0.05). Reaching-forward motion was caused a higher %MVIC on non-dominant external oblique muscle than that of the chest-expansion motion (p<0.05). Regardless of dominant or non-dominant sides, external oblique muscle was shown the highest activation rate of all the other muscles during reaching forward action, and longissimus thoracic muscle was shown the highest activation rate of all the other muscles during chest expansion action. Conclusion: Reaching-forward motion is suitable for activating an external oblique muscle, and chest-expansion motion is an effective enough in activating of longissimus thoracic muscle.
반복적 검도 토너먼트 경기 수행이 엘리트 검도 선수의 혈중 가스, 이온, 및 피로 부산물 농도에 미치는 영향
하재운 ( Jaewoon Ha ),허성훈 ( Sunghoon Hur ),안경준 ( Kyungjun An ),이종삼 ( Jongsam Lee ),권영우 ( Youngwoo Kwon ) 한국스포츠정책과학원(구 한국스포츠개발원) 2016 체육과학연구 Vol.27 No.4
이 연구는 엘리트(elite) 학생 검도선수들의 가상 검도 개인전 토너먼트 경기 수행 시 나타나는 혈중 구성성분과 피로물질의 변화 양상을 조사해 엘리트 검도선수들의 경기력 향상을 위한 기초자료를 제공하기 위해 수행되었다. 연구를 위해 경상북도 소재의 D대학 학생 검도 선수 중 개인전 입상 경험이 있는 8명(최대산소섭취량, 51.5±8.8 mL·kg<sup>-1</sup>min<sup>-1</sup>; 체지방율, 12.4±8.8 %)의 선수를 선발하였으며 실제 경기 상황을 가정해 전국 규모의 시합에서와 같이 64강부터 결승까지 총 6번의 경기를 치르도록 실험 설계를 하여 혈액 내 가스, 이온, 에너지 기질, 및 피로 부산 물질들에 대한 분석을 수행하였다. 이원변량분석(TWOWAY ANOVA)을 통해 두 요인 간(, 토너먼트 라운드 x 경기 전과 후) 상호작용과 주효과를 검증하였으며 통계적 유의 수준은 α=.05로 설정하였다. 혈중 수소 이온 농도와 산소 분압은 유의한 영향을 받지 않은 반면, 이산화탄소 분압은 시합이 반복됨에 따라 뚜렷한 감소 경향을 나타냈다. 헤마토크리트와 헤모글로빈은 토너먼트 초반부에서만 유의한 증가를 나타냈다. 혈중 Na<sup>+</sup> 농도는 토너먼트가 진행될수록 증가하는 결과를 나타낸 반면, K<sup>+</sup> 농도는 감소하는 양상을 나타냈으며 Ca<sup>2+</sup>의 농도는 변화를 나타내지 않았다. 혈중 포도당은 변화의 양상이 일정하게 나타나지 않았으나 경기 전과 비교해 경기 종료 후 증가하는 경향이 두드러졌으며 젖산과 암모니아, 요산의 농도는 경기 후 그리고 토너먼트의 진행에 따라 축적되는 결과를 나타냈다. 이와 함께, 유리지방산은 토너먼트의 진행에 따라 농도의 상승을 나타냈으며 심박수의 변화는 토너먼트가 진행됨에 따라 유의한 변화를 나타내지 않았다. 이와 같은 결과는 반복적으로 토너먼트 경기에의 참여가 혈중 피로 부산 물질의 축적을 유발하고 다양한 이온 성분과 에너지 기질에 유의한 변화를 야기함을 확인하는 것이었다. 따라서 제한된 시간 내에 반복적으로 경기를 치루는 검도 토너먼트 경기에의 참가 시 피로 관리 및 에너지 기질의 적절한 공급을 이루어낼 수 있는 대책 마련이 요구된다 하겠다. This study aimed to examine the change of the indices in blood gas, ions, and by-products of fatigue substances and components in collegiate elite Kumdo competitors, who carry out a number of competitive games during one day tournament event. Subjects were carried out total 6 simulated, but followed same conditions and rules of actual competition, with providing similar inter-game break time. Eight well trained male competitors, who had awarded from national wide competitions, voluntarily participated in this study and revealed 51.5(±8.8) mL·kg<sup>-1</sup>min<sup>-1</sup>of maximal oxygen consumption and 12.4(±5.1) % body fat. TWOWAY ANOVA (tournament round vs. pre & post each game) was adopted to test whether the mean differences were existed, and the interaction between individual factors and main effect within each factors were analyzed. Statistical significance was set at Alpha (α) = .05. While there were no significant changes in blood hydrogen ion concentration (i.e., pH) and partial pressure of oxygen (PO<sub>2</sub>), partial pressure of carbon dioxide (PCO<sub>2</sub>) significantly decreased as the tournament games were repeated. The level of hemoglobin and hematocrit were significantly elevated only during the 1<sup>st</sup> round of tournament. Na<sup>+</sup> was significantly increased but K<sup>+</sup> was decreased. Ca<sup>2</sup>+ concentration however, was not significantly altered. Although the changes of blood glucose level did not show any consistent patterns, free fatty acid (FFA) concentration was increased after completed each game compared to prior to initiate the each game. Blood NH<sub>3</sub>, lactic acid, and uric acid concentration increased at immediately after each game, and the pattern was maintained throughout the tournament round continued. These results reflected that the repeated participation of the tournament may cause the accumulation of the by-products of fatigue substances in blood and alteration of various ion components and energy substrates. Accordingly, the ways of reducing the physical fatigue and providing adequate energy source inter-tournament games needs to be necessarily considered for successful Kumdo competition. Data obtained from this study could valuable for searching the effective training and management methods to improve the performance and reduce the fatigue of the professional elite Kumdo competitors.