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권영두(Young-Doo Kwon),장석호(Suck-Ho Jang),박상현(Sang-Hyun Park),이상원(Sang-Won Lee) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.3
After scientific verification of the osteointegration of dental implants, the overall efficiency of dental implants has been generally accepted. Thus, implants now play a major role in the clinical treatment of an edentulous mandible, and in the prosthetic maintenance equipment for partial edentulous mandible patients. Yet, for the successful long-term maintenance of implants, careful consideration of the bio-mechanics is needed to ensure that the maximum stress in the mandible as a result of chewing is maintained under a critical value. Accordingly, this study focuses on reducing the maximum stresses in an implanted mandible, especially in the cortical bone. Thus, the stresses in the implant and mandible are analyzed using finite element packages, including I-DEAS and NISA II/DISPLAY III, using a local zooming technique for a concentrated stress analysis. In addition, the von-Mises stress and principal stress in the mandible are both checked to determine the best combination.
권영두(YOUNG-DOO KWON),권현욱(HYUN-WOOK KWON),신상목(SANG-MOK SHIN),이찬복(CHAN-BOK LEE) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.5
Long cylinder, subjected to internal pressure, is important in the analysis and design of nuclear fuel rod structures. In many cases, long cylinder problems have been considered as a plane strain condition. However, strictly speaking, long cylinder problems are not plane strain problems, but rather a general plane strain (GPS) condition, which is a combination of a plane strain state and a uniform strain state. The magnitude of the uniform axial strain is required, in order to make the summation of the axial force zero. Although there has been the GPS element, this paper proposes a general technique to solve long cylinder problems, using several pseudo-general plane strain (PGPS) elements. The conventional GPS elements and PGPS elements employed are as follows: axisymmetric GPS element (GA3), axisymmetric PGPS element (PGA8/6), 2-D GPS element (G10), 3-D PGPS element (PG20/16), and reduced PGPS elements (RPGA6, RPG20/16). In particular, PGPS elements (PGA8/6, PG20/16) can be applied in periodic structure problems. These finite elements are tested, using several kinds of examples, thereby confirming the validity of the proposed finite element models.
순차적 주밍 유전자 알고리즘 기법에 사용되는 파라미터의 최적화 및 검증
권영두(YOUNG-DOO KWON),권현욱(HYUN-WOOK KWON),김재용(JAE-YONG KIM),진승보(SEUNG-BO JIN) 한국해양공학회 2004 韓國海洋工學會誌 Vol.18 No.5
A new approach, referred to as a successive zooming genetic algorithm (SZGA), is proposed for identifying a global solution, using continuous zooming factors for optimization problems. In order to improve the local fine-tuning of the GA, we introduced a new method whereby the search space is zoomed around the design variable with the best fitness per 100 generation, resulting in an improvement of the convergence. Furthermore, the reliability of the optimized solution is determined based on the theory of probability, and the parameter used for the successive zooming method is optimized. With parameter optimization, we can eliminate the time allocated for deciding parameters used in SZGA. To demonstrate the superiority of the proposed theory, we tested for the minimization of a multiple function, as well as simple functions. After testing, we applied the parameter optimization to a truss problem and wicket gate servomotor optimization. Then, the proposed algorithm identifies a more exact optimum value than the standard genetic algorithm.
근막이완 기법과 심부 근육 마사지가 운동 후 체내 생리적, 심리적 회복에 미치는 영향 분석
권영두(Kwon, Young-Doo),고재문(Koh, Jae-Moon),김남수(Kim, Nam-Soo) 한국체육과학회 2019 한국체육과학회지 Vol.28 No.5
The study investigated the most effect management for delay onset of muscle soreness(DOMS) and psychological stability by comparison between myofascial release technique(MR technique) and deep tissue massage(DT massage). Fifteen young males who performed strength exercise by weight lifting were divided into MR technique(n=5), DT massage(n=5) and control group(CG, n=5). Each therapeutic procedure was done twice at a week after training and visual analogue scale(VAS) of DOMS at 24 hours and 48 hours after training were checked, respectively. After 4 weeks, flexibility, muscle size and psychological effect on anxiety, depression, stress and sleep quality of each groups were evaluated. The results of the difference between before and after the treatment are as follows. For DOMS and flexibility, DT massage was most effective for relieving soreness(p=.016). DT massage and MF technique showed more effective in providing psychological stability compared with CG(p<.001). No significant differences were found between three groups on muscle size increase. In between three groups, DT massage is most effective on DOMS and psychological stability.
근막 이완처치와 심부 근육마사지가 보디빌딩 선수들의 운동 후 DOMS 회복과 생리적, 심리적 요인에 미치는 영향
권영두(Kwon, Young-Doo),김남수(Kim, Nam-Soo),김정원(Kim, Jeong-Weon) 한국체육과학회 2021 한국체육과학회지 Vol.30 No.6
This study analyzed the effective management to bodybuilders for delay onset of muscle soreness (DOMS), physiological factors and psychological stability by comparison between myofascial release technique (MF technique), deep tissue massage (DT massage) and both. Ten young adult males who experienced bodybuilders performed strength exercise by weight lifting were recruited. Each therapeutic procedure was done for 2 weeks after training and visual analogue scale (VAS) of DOMS at 24 hours and 48 hours after training were checked, respectively. Each therapeutic procedure was done for 2weeks, and than flexibility, muscle size, blood levels of LDH, CK, cortisol, hormones and hemoglobin and psychological effect on depression, anxiety, stress and sleep quality of each groups were evaluated. The results of the difference between before and after the treatment are as follows. For DOMS and flexibility, DT massage and both technique were more effective methods for relieving soreness than MF technique. Psychologic releaf was observed in both techniques, DT massage showed more effective in providing psychological stability compared with MF technique. And serum cortisol level was decreased after DT massage and both technique. No differences were observed between three groups on muscle size gain significantly. In between three groups, DT massage is more effective method on DOMS and psychological stability of athletes than MF technique.
김경식,권영두,권순범,길혁문,Kim, Kyung-Sik,Kwon, Young-Doo,Kwon, Soon-Bum,Gil, Hyuck-Moon 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.6
High-maneuver missile is a projectile which demands a strong momentum at short time. To produce a necessary thrust for the flight, the gas of high temperature and pressure is generated through explosive combustion of solid propellant, and a great thrust can be obtained by expanding this high temperature and pressure gas. Although the operating time of a rocket motor is less than a few seconds, a failure of part or ablation near the throat of nozzle may take place during the expansion of high temperature and pressure gas for great thrust. In other words, for the precise control of a missile an exact stress analysis considering both, the thermal stress caused by the heat transfer between combustion gas and wall, and the mechanical stress caused by the pressure change in the flow, should be considered first. In this connection, this study investigated the safety, as a point of view of stress and melting point of the material, of the pre-designed thrust generating structure which is subjected to high temperature and pressure as a function of motor operating time. 고기동 유도탄은 짧은 시간에 큰 추력을 필요로 하는 발사체이다. 유도탄의 비행에 필요한 추력을 얻기 위하여 고체 연료를 폭발적으로 연소시키면 고온, 고압의 연소 가스가 발생되고, 이 연소 가스를 초음속 노즐을 통하여 팽창시킴으로서 큰 추력을 얻게 된다. 로켓 모터의 작동 시간은 수초 미만에 지나지 않으나 큰 추력을 내기 위해 고온 고압의 연소 가스가 이용됨으로 평창 과정 중 시스템 부품의 파손 혹은 노즐목 부근에서 삭마현상이 발생되기도 한다. 즉, 탄의 정확한 제어를 위해서는 연소 가스와 벽면과의 열전달에 따른 열응력과 유동장 내의 압력의 변화에 따른 구조체 응력이 동시에 고려된 정확한 응력해석이 선행되어야만 한다. 본 논문에서는 예비 설계된 추력 발생장치에 고온 고압의 연소 가스가 유동할 때 모터의 작동시간에 따른 구조체의 안전성을 응력과 재료의 용융온도의 측면으로부터 구명하였다.