• 한국체육학회지인문사회과학편
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• v.54 no.5
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• pp.829-840
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• 2015

The purpose of this study was to investigated into the kinematics and ground reaction force for gait on induced stereoacuity in normal subjects with normal sight. Eighteen subjects who passed the stereoacuity testing were participated in the experiment(age: 22.1±2.7 years, height: 176.8±4.4 cm, weight: 67.6±5.8 kg). The study method adopted 3D analysis with six cameras and ground reaction force with two force-plates. The results were as follows; In gait velocity, obstacle crossing gait was slower than flat gait. In angular displacement of hip joint, mostly obstacle crossing gait was more flexed than flat gait. In angular displacement of knee joint, obstacle crossing gait was more flexed than flat gait, and stereoacuity reduction gait in TO and FC2 were more flexed than normal vision gait. In angular displacement of ankle joint, obstacle crossing gait in FC2 was more flexed than flat gait. In trunk tilt, obstacle crossing gait in MSt, TO and MSw were more extended than flat gait. In GRF, there was no significant in Fx, obstacle crossing gait in right and left foot were bigger propulsion force than flat gait, obstacle crossing gait in right and left foot were bigger braking force than normal vision gait in Fy, and obstacle crossing gait in right and left foot were bigger than flat gait in peak F1 and peak F2 of Fz, and stereoacuity reduction gait in right foot was lower than normal vision gait in valley force of Fz.

• Journal of the Korea Computer Graphics Society
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• v.3 no.1
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• pp.57-67
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• 1997

The navigation of virtual space comes down to the manipulation of the virtual camera. The movement of the virtual cameras has 6 degrees of freedom. However, input devices such as mouses and joysticks are 2D. So, the movement of the camera that corresponds to the input device is 2D movement at the given moment. Therefore, the 3D movement of the camera can be implemented by means of the combination of 2D and 1D movements of the camera. Many of the virtual space navigation browser use several navigation modes to solve this problem. But, the criteria for distinguishing different modes are not clear, somed of the manipulations in each mode are repeated in other modes, and the kinesthetic correspondence of the input devices is often confusing. Hence the user has difficulty in making correct decisions when navigating the virtual space. To solve this problem, we use a single navigation metaphore in which different modes are organically integrated. In this paper we propose a helicopter pilot metaphor. Using the helicopter pilot metaphore means that the user navigates the virtual space like a pilot of a helicopter flying in space. In this paper, we distinguished six 2D movement spaces of the helicopter: (1) the movement on the horizontal plane, (2) the movement on the vertical plane,k (3) the pitch and yaw rotations about the current position, (4) the roll and pitch rotations about the current position, (5) the horizontal and vertical turning, and (6) the rotation about the target object. The six 3D movement spaces are visualized and displayed as a sequence of auxiliary windows. The user can select the desired movement space simply by jumping from one window to another. The user can select the desired movement by looking at the displaced 2D movement spaces. The movement of the camera in each movement space is controlled by the usual movements of the joystick.

• Journal of Biomedical Engineering Research
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• v.19 no.4
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• pp.385-391
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• 1998

A new balancing method of atrial pressures balancing for the moving actuator total artificial heart(TAH) without an extra compliance chamber was developed. The asymmetric operation of the pendulous moving actuator have made it possible to compensate the left and right pump output difference by utilizing the interventricular air space as an internal compliance chamber in a pump housing. Furthermore, the balancing performance between left and right pump outputs is increased through the improvement of the flexibility of part of the polyurethane housing. However, the increase of the flexibility of the pump housing causes a little loss of the cardiac output due to the reduction of active filling property. In this paper., a good condition between the balance and pump output performance is evaluated by adjusting the air volume in the interventricular space through a series of in vitro experiments. This new pump was implanted in a sheep weighting 63kg, and it survived for 3 days and the average cardiac output during postoperative days was about 4.2 L/mim with the atrial pressures under 15 mmHg.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.291-296
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• 2021

This study examined the effects of the forward head posture on the maximum mouth opening of the jaw joint and the muscle activity and asymmetry of the temporalis and masseter. The craniovertebral angle was measured in 50 subjects (23.10±2.73 years) who met the selection requirements of the study. The maximum mouth opening, muscle activity, and muscle asymmetry were measured by reducing 0%, 10%, and 20%. As the craniovertebral angle decreased, the maximum mouth opening decreased (p<.001), the muscle activity of the right and left temporalis decreased (p<.001), and the muscle activity of the left temporalis also decreased. (p<.01). The asymmetry rate of the added muscles of the left and right temporalis, left and right temporalis, and masseter increased according to the change in condition (p<.01). The results of this study are expected to help establish a treatment strategy and comprehensive diagnosis for the temporomandibular joint and present a theoretical basis of manual therapy and therapeutic exercises used for the treatment of TMD.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.73-76
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• 2009

Purpose: Bone mineral densitometry test region advised by ISCD (International Society for Clinical Densitometry) is both site in case of femur, whereas our medical center measures left femur except for few extraordinary cases. It is said that right-handers had higher mean femur BMD in the left side than in the right side, but the factor influence the femur BMD is unknown. Thus, we investigate whether testing left femur only is a adequate clinical diagnosis. Materials and Methods: Subjects were 209 right-handers and 20 left-handers patient in Asan Medical Center from July to August, 30 to 70 years of age ($51{\pm}6.7$). Subjects fill out the questionnaire on hand preference and taking regular exercise. Total BMDs of bilateral femur were measured with GE Lunar Prodigy advance densitometer, and the statistical soft ware SPSS 12.0 for windows was used for statistical analysis. Results: In the total sample of the exercise group (n=127), the difference of both femur mean BMDs are $0.001{\pm}0.127\;g/cm^2$ and the non-exercise group's (n=102) both femur difference is $0.002{\pm}0.126\;g/cm^2$, there is no significant difference. And in exercise group, classified according to hand preference, each t-value is shown at right handers (n=114) are 0.65, left handers (n=13) are -0.39. Also, In non-exercise group, right handers (n=95) are -0.78, left handers (n=7) are -0.64. In the 95% confidence limit, there was no statistically significant difference (p>0.05). Conclusions: In recently researchs, there have been differences between both femurs according to hand preference. However, Our study have no significant difference both femurs BMDs. Therefore we suggest that BMD measurement of femur has no problem only one side, except for particular case like femur operation.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.2
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• pp.53-60
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• 2003

For the high center of gravity vehicles the roll stiffness of their suspensions is arranged to be very high because such vehicles are in some danger of tipping over in cornering. In some cases, the effective roll stiffness is determined significantly by the compliance of the tires because of the very stiff anti-roll members incorporated in the suspension. In such cases, it is clear that the shock absorbers which may be effective in damping heave oscillations have little effect on roll oscillations. Therefore, wind gusts and roadway unevenness may cause large swaying oscillations. In this paper, to improve the stability for the high center of gravity vehicles a control scheme to augment the damping of the roll mode is proposed. As the feedback signals needed to provide damping of the roll motion, the front or rear steer angles or both are chosen because they are very related to roll motion. The scheme is effective from moderate to high speeds and stabilizes the roll mode without introducing disturbance moments from roadway unevenness as shock absorbers do. The validity on the proposed method is verified through the computer simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5148-5154
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• 2012

The purpose of this study was to analyze the kinematic characteristics of the thrower's center of mass (COM) and the shot that her performance hits record high for the 29th National Athletic Competition. Two S-VHS video cameras were used to visualize. The Direct Linear Transformation technique was employed to paint a clear picture in the three dimensional coordination. Kwon3D was used to analyze the data. The results showed that release velocity and height were 13.73 m/s and 198.6 cm(119% by height ratio), respectively, which is considered as peak performance comparing an extensive review of previous literature on the shot put. Release angle was $34^{\circ}$, which is lower than the previous studies. The path of thrower's center of mass is needed to travel in a release direction during the flight phase. The vertical movement of the thrower's center of mass during the driving should be controlled. At release, the perfact timing is required without vertical and horizontal movements of the thrower's center of mass.

• Journal of Digital Convergence
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• v.13 no.8
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• pp.495-502
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• 2015

The purpose of this study was to investigating the effect of taping knee by testing the difference on kinetic variables of lower extremity when speed skating athletes jump on one leg. The results were as follows. The height of jumping after taping was higher, but the vertical height was not different according to taping. On take-off(TO), the horizontal and anterior-posterior maximum impulse force were decreased while the vertical maximum impact force was increased after taping. On landing(LD), the anterior-posterior maximum impulse force was decreased but the horizontal and vertical maximum impulse force were increased. TO, the impulse showed low after taping and the impulse dropped largely LD. The knee's moment of extension, eversion were reduced after tapping TO. LD, the flection moment of knee was decreased, but the inversion moment was increased after tapping. This study implies that the knee tapping helps injury prevention and performance enhancement, sports medicine convergence are needed.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.309-315
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• 2011

The purpose of this study was to evaluate the effect of asymmetric muscle force in lower extremity on dynamic balance during walking. Sixteen elementary students(age: 12.3${\pm}$0.7 yrs, height: 149.4${\pm}$9.7 cm, weight 40.6${\pm}$7.8 kg) who have no musculoskeletal disorder were recruited as the subjects. Temporal parameters, M-L inclination angle of XCoM-CoP, M-L and A-P CoP, loading rate, and decay rate were determined for each trial. For each dependent variable, a independent-sample t-test was performed to test if significant difference existed between each conditions(p<.05). The displacement of antero-posterior COP during RTO-LHC1 in SG was siginificantly smaller than corresponding value in AG. In contrast, the displacement of medio-lateral COP during RTO-LHC1 in SG was greater than those of AG. It seems that imbalance of muscle force may result in increasing the medio-lateral stance in order to minimize the instability. We found that the asymmetric muscle force in the lower extremity may be a reason for the awkward control of impact force.

• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.229-236
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• 2012

The purpose of this study is to analyze the differences in foot type of female college students according to academic major in both feet. The subjects for this study were 216 female students who took liberal arts classes in Seoul. Dependent variables were students' field of study -specifically whether or not they majored in physical education. Analysis of students' foot type and Malalignment Syndrome were measured using Resting Calcaneous Stance Position (RCSP). There were five categories for RCSP angle: Severe Pes Planus (< $-5^{\circ}$), Pes Planus ($-3^{\circ}{\sim}-4^{\circ}$), Pes Rectus (${\pm}2^{\circ}$), Pes Cavus ($+3^{\circ}{\sim}+4^{\circ}$), Severe Pes Cavus (> $+5^{\circ}$). ${\chi}^2$ analysis was used for statistical analysis. RCSP for all subjects (432 feet) occurred at the following frequency: Pes Planus(43.9%), Pes Rectus(43.8%), and Pes Cavus(12.3%). These levels were different for physical education majors, with Pes Planus at 42.6%, Pes Rectus at 49.4%, and Pes Cavusat 8.0%. Non-physical education majors exhibited Pes Planus at 45.0%, Pes Rectus at 39.9%, and Pes Cavus at 15.1%. 15.3% (33 subjects) of all students had Malalignment Syndrome. In conclusion, 56.2% of female college students had a foot deformity. There was nearly four times more Pes Planus than Pes Cavus. According to these results, exercise can be prescribed to alleviate foot deformities, especially supination. Severe pronation and supination problems appeared less amongst students not majoring in physical education. Thus, although exercise might be one cause of foot deformity, it can also help resolve problems with over-supination. Further study will be needed to understand and resolve the specific mechanism of over-supination.