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분사시기와 피스톤 형상에 의한 연료 증기상의 공간분포에 관한 연구
강정중(Jeong-jung Kang),김덕줄(Duck-jool Kim) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.2002 No.3
This work is to investigate the spatial distribution of fuel vapor phase with different injection timing and piston cavity in a optically accessible engine. Two dimensional spray fluorescence image of fuel vapor phase was captured under the motoring condition using LIEF method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. To generate swirl motion of intake flow, mask was installed at the inlet of the intake port. Three different piston types, F, Band R-type were used. Four injection timings were set at BTDC 90˚, 80˚ ,70˚ , and 60˚ . At a fuel injection timing of BTDC 90˚ , fuel-rich mixture level in the center region was highest in a B-type piston, while fuel vapor was transported to the exhaust valve by swirl flow in F, R-type pistons. At a fuel injection timing of BTDC 60˚ , R-type piston was better in stratification than the others. It is found that R-type piston was suitable under enhanced swirl ratio condition.
뇌졸중 환자에서 자세정렬변화가 족저압 및 균형에 미치는 영향
양대중,박승규,강정일,박성빈,Yang, Dae-Jung,Park, Seung-Kyu,Kang, Jeong-Il,Park, Seong-Bin 대한물리치료학회 2014 대한물리치료학회지 Vol.26 No.4
Purpose: This study was conducted in order to investigate the exercise limit that may occur depending on changes in postural alignment by examining the significance of postural alignment changes, foot pressure, and balance of patients with stroke. Methods: In this study, 50 patients diagnosed with a stroke were selected as subjects. Imbalance of postural alignment of the trunk, pelvic tilt of trunk rotation of the body, angle of kyphotic curving of the thoracic, and angle of lordotic curving of the lumbar vertebra were measured. Foot pressure was examined by measuring average pressure and weight bearing. Balance was examined by measuring the center of pressure and limit of stability. Results: The significance of postural alignment, foot pressure, and weight bearing of the non-paretic side was examined. In addition, the significance between postural alignment and balance was examined. Conclusion: It is thought that limits of foot pressure and balance in the standing position can be caused by postural alignment. Thus, both a therapeutic intervention program and postural alignment training should be provided together in order to improve the function of patients with stroke.
자가 신장운동이 전방머리자세를 동반한 만성 목통증 환자의 자세개선에 미치는 영향
강정일 ( Jeong-il Kang ),정대근 ( Dae-keun Jeong ),박승규 ( Seung-kyu Park ),양대중 ( Dae-jung Yang ),김제호 ( Je-ho Kim ),문영준 ( Young-jun Moon ),백승윤 ( Seung-yun Baek ) 대한물리의학회 2020 대한물리의학회지 Vol.15 No.3
PURPOSE: The purpose of this study was to provide clinical basic data to reduce pain and improve function by comparing neck muscle activity and neck alignment using self-stretching and passive stretching exercises for chronic neck pain caused by forward head posture. METHODS: The subjects were divided into 15 subjects assigned to perform self-stretching exercise and 15 subjects assigned to perform passive stretching exercise. The intervention was conducted for a total of 4 weeks. The muscle activity in the neck was measured by surface electromyography (EMG) before intervention, and craniovertebral and cranial rotation angles were measured by X-ray. The 4-week intervention was conducted and the above items re-measured in the same manner and analyzed. RESULTS: Muscle activity within both groups after intervention using self-stretching or passive stretching exercise was significantly different (p < .05)(p < .01). Neck alignment of both groups was significantly different (p < .001)(p < .01). Further, muscle activities of the upper trapezius and splenius capitis muscles showed significant differences (p<.05). Lastly, neck alignment showed statistically significant difference (p < .05). CONCLUSION: Self-stretching exercise activated motor nerves as a posture correction exercise, thereby improving inhibition of muscle activity, muscle contraction delay, and pathological conditions of the muscle. For future research, interventions of self-stretching exercise will be needed for patients with chronic back pain accompanied by forward head posture, and various clinical studies on postural improvement of forward head posture by maintaining a normal muscle tone state are needed.
신경근 훈련이 기능적 발목 불안정성 축구선수의 자세조절과 점프 수행력에 미치는 영향
양대중 ( Dae Jung Yang ),강정일 ( Jeong Il Kang ),박승규 ( Seung Kyu Park ),이민기 ( Min Ki Lee ),정용식 ( Yong Sik Jeong ) 한국운동역학회 2014 한국운동역학회지 Vol.24 No.3
The purpose of this study was to investigate the effects on jump performance and balance in soccer player with functional ankle instability of difference of neuromuscular training. In 33 male college soccer player with functional ankle instability subjects of this study randomization, combined training group (group I, n=11) , balance training group (group II, n=11) and control group (group III, n=11) that included in the plyometric training and balance training was classified group. The intervention was conducted three times a week for 8 weeks. Before and after intervention, measured in surface area ellipse and countermovement jump and countermovement jump with arm swing. Showed a significant improvement in postural control and jump performance from the combined training group and balance training group compared to the control group. Showed a significant improvement in countermovement jump from the combined training group compared to the balance training group. Combined training and balance training showed the increased jump performance and postural control in soccer player with functional ankle instability.
계단 오르기 시 정강이뼈 돌림이 하지의 역학과 근 활성도에 미치는 영향
강정일 ( Jeong Ii Kang ),이유경 ( Yu Kyung Lee ),박승규 ( Sung Kyu Park ),이준희 ( Joon Hee Lee ),양대중 ( Dae Jung Yang ),최현 ( Hyun Choi ) 한국운동역학회 2011 한국운동역학회지 Vol.21 No.4
This study was performed to investigate the effects of tibial rotation while going up stair on muscle activity of vastus medialis oblique and vastus lateralis, and on patellar displacement. The subjects included 30 people (male: 15; female: 15) who were randomly assigned to the tibial internal-rotation, neutral-rotation, and external-rotation groups, The subjects went up the stair while performing the assigned rotations, and the rotation of the hip and the displacement of the patella were measured using a 3D motion analyzer. In addition, the maximum voluntary isometric contraction (MVIC) of the vastus medialis oblique and vastus lateralis were measured using surface electromyogram. On the tibial internal rotation, the hip rotation significantly appeared in the same direction and so did on the tibial neutral and external rotations (p<.001). Although the MVIC of the vastus medialis oblique and vastus lateralis did not significantly differ by tibial rotation during the stair ascent, the MVIC of the vastus medialis oblique was higher than that of the vastus lateralis during the internal and neutral rotations (p<.05). In addition, during the stair ascent, the displacement of the patella was more significant during the tibial external rotation than during the tibial internal and neutral rotations (p<.001). Thus, patients with patellofemoral pain are required to be considered the effects of tibial rotation for their rehabilitation.
DI 가솔린 기관의 피스톤 캐비티 직경에 따른 연료의 액.기상 거동
강정중(Jeong-Jung Kang),김태안(Tae-An Kim),김덕줄(Duck-Jool Kim) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This study was performed to investigate the behavior of liquid and vapor phases of fuel mixtures with different piston cavity diameters in a optically accessible engine. The images of liquid and vapor phases were measured in the motoring engine using LIEF method. Injection pressure is 5.1 MPa. Two dimensional spray fluorescence images of liquid and vapor phases were acquired to analyze spray behavior and fuel distribution inside of cylinder. Three injection timings were set at bTDC 180°, 90°and 60°. The results obtained are as follows. With a fuel injection timing of bTDC 60°, fuel-rich mixture was concentrated in near the cavity center. With a fuel injection timing of bTDC 90°, fuel-rich mixture level in the center region was highest in the Type-M during the compression stroke. With a fuel injection timing of bTDC 180°, fuel was not affected in a piston cavity and generally distributed as homogeneous mixture. The spray dispersion at injection timing of bTDC 90° was smaller than bTDC 300°.<br/>
노르딕워킹의 속도에 따른 하지 관절의 운동역학적인 분석
양대중 ( Dae Jung Yang ),이용선 ( Yong Seon Lee ),박승규 ( Seung Kyu Park ),강정일 ( Jeong Il Kang ),이준희 ( Joon Hee Lee ),강양훈 ( Yang Hoon Kang ) 한국운동역학회 2011 한국운동역학회지 Vol.21 No.3
In this study, 26 normal subjects were studied to compare the biomechanical Analysis of Lower Limbs on Speed of Nordic Walking. The biomechanical variables were determined by performing three-dimensional gait analysis, and the measurements items were spatial and temporal parameters; vertical ground reaction force; and moments of the hip, knee, and ankle joints. The purpose of this study based on the speed of Nordic Walking to the vertical ground reaction force and joint moments of each were analyzed. Nordic Walking with poles while being whether this weight is reduced to load, not the improvement of muscle activity by identify Nordic walking is to allow efficient. The results of the analysis were follows. The spatial parameters of step length, stride length significantly increased with increase in velocity(p<0.001). The temporal parameters of step time, stride time, the duration of double support use, and the duration of single support use also significantly decreased with increase in velocity(p<0.001), but cadence significantly increased(p<0.01). Analysis of the changes in ground reaction force revealed that vertical ground reaction force significantly increased at the initial contact and the terminal stance and decreased at the mid stance with increase in velocity(p<0.001). Moments of the hip and knee joints significantly in creased with increase in velocity whereas that of the ankle joint did not. Gait analysis revealed that weight-bearing decreased and moments of the hip and knee joints increased with increase in velocity(p<0.01). The results of this study may help people perform Nordic walking efficiently and Nordic walking can be used in the gait training of people with an abnormal gait.
운동프로그램 중재가 돌림근띠 복원술 환자의 근 활성도에 미치는 영향
강정일,문영준,박승규,이준희,양대중,최현,정대근,김용남,권혜민,Kang, Jeong-Il,Moon, Young-Jun,Park, Seung-Kyu,Lee, Joon-Hee,Yang, Dae-Jung,Choi, Hyun,Jeong, Dae-Keun,Kim, Yong-Nam,Kwon, Hye-Min 대한물리치료학회 2013 대한물리치료학회지 Vol.25 No.2
Purpose: This study was conducted in order to examine how an effective rehabilitation exercise program influences the activity of shoulder muscles, and to help the clinical application of a rehabilitation program, for prevention and relief of pain, adhesion, and joint stiffness of patients who undergo rotator cuff repair. Methods: Nine test subjects were placed randomly into each group for a total of 27 subjects and exercise program interventions according to the group were conducted for six weeks, after which maximum voluntary isometric contraction (%MVIC) value was re-measured for supraspinatus muscle, infraspinatus muscle, serratus anterior muscle, and middle deltoid muscle in all groups in order to compare changes in muscle activity before and after the experiment in order to perform comparative analysis of changes in muscle activity between groups, based on which four experimental hypotheses were confirmed. Results: Changes in muscle activity according to %MVIC showed a statistically significant difference (p<0.01) (p<0.001) in all muscles, except the middle deltoid muscle, and post-verification results showed that changes in muscle activity according to %MVIC were greater in test groups I and II, compared with the control group, for the supraspinatus muscle, infraspinatus muscle, and serratus anterior muscle. Conclusion: Therefore, rehabilitation through use of the methods described above should be applied efficiently in clinical settings and more research in development of much more efficient rehabilitation program interventions must be conducted.