• 한국운동역학회지
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• 제25권4호
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• pp.489-498
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• 2015

Objective : The purpose of this study was to analyze the effects of the windlass mechanism in trail-walking shoe prototypes that can effectively support arches. A study of these effects should help with the development of a first-rate trail-walking shoe development guide for the distribution of quality information to consumers. Methods : The subjects were ten adult males who volunteered to participate in the study. Shoes from three companies, which will be referred to as Company S (Type A), Company M (Type B), and Company P (Type C), were selected for the experiment. The subjects wore these shoes and walked at a speed of 4.2 km/h, and as they tested each shoe, the contact area, maximum pressure average, and surface force were all measured. Results : Shoe Type A showed a contact area of $148.78{\pm}4.31cm^2$, Type B showed an area of $145.74{\pm}4.1cm^2$, and Type C showed an area of $143.37{\pm}4.57cm^2$ (p<.01). Shoe Type A demonstrated a maximum average pressure of $80.80{\pm}9.92kPa$, Type B an average of $85.72{\pm}11.01kPa$, and Type C an average of $89.12{\pm}10.88bkPa$ (p<.05). Shoe Type A showed a ground reaction force of $1.13{\pm}0.06%BW$, Type B a force of $1.16{\pm}0.04%BW$, and Type C a force of $1.16{\pm}0.03%BW$ (p<.05). Conclusion : The Type A trail-walking shoe, which was designed with a wide arch from the center of the forefoot to the front of the rearfoot showed excellent performance, however, more development and analysis of the windlass mechanism for a variety of arch structures is still necessary.

• 한국운동역학회지
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• 제27권3호
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• pp.171-179
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• 2017

Objective: The purpose of this study was to perform a kinematic and kinetic analysis of double-under jump rope technique according to skill level and sex. Method: Participants comprised a skilled group of 16 (9 males, 7 females), and an unskilled group of 16 with 6 months or less of experience (9 males, 7 females). Five consecutive double-under successes were regarded as 1 trial, and all participants were asked to complete 3 successful trials. The data for these 3 trials were averaged and analyzed after collecting the stable third jump in each trial. The variables used in the analysis included phase duration, total duration, flight time, vertical toe height, stance width, vertical center of mass displacement, and right lower limb ankle, knee, and hip joint angles in the sagittal plane during all events. Results: The skilled group had a shorter phase and total duration and a shorter flight time than the unskilled group. The vertical center of mass displacement and ankle dorsiflexion angle were significantly smaller in the skilled group. The male group had a shorter phase duration than the female group. The vertical toe height was greater, the stance width was smaller, and the ankle and hip flexion angles were smaller in the male group. Conclusion: Variables that can be used to distinguish between skill levels are phase and total duration, flight time, vertical center of mass displacement, and ankle dorsiflexion angle. Differences between sexes in double-under jump rope technique may be related to lower limb flexion angle control.

• 한국운동역학회지
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• 제27권3호
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• pp.189-195
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• 2017

Objective: The aim of this study was to examine the effect of foot landing type (forefoot vs. rearfoot landing) on kinematics, kinetics, and energy absorption of hip, knee, and ankle joints. Method: Twenty-five healthy men performed single-leg landings with two different foot landing types: forefoot and rearfoot landing. A motion-capture system equipped with eight infrared cameras and a synchronized force plate embedded in the floor was used. Three-dimensional kinematic and kinetic parameters were compared using paired two-tailed Student's t-tests at a significance level of .05. Results: On initial contact, a greater knee flexion angle was shown during rearfoot landing (p < .001), but the lower knee flexion angle was found at peak vertical ground reaction force (GRF) (p < .001). On initial contact, ankles showed plantarflexion, inversion, and external rotation during forefoot landing, while dorsiflexion, eversion, and internal rotation were shown during rearfoot landing (p < .001, all). At peak vertical GRF, the knee extension moment and ankle plantarflexion moment were lower in rearfoot landing than in forefoot landing (p = .003 and p < .001, respectively). From initial contact to peak vertical GRF, the negative work of the hip, knee, and ankle joint was significantly reduced during rearfoot landing (p < .001, all). The contribution to the total work of the ankle joint was the greatest during forefoot landing, whereas the contribution to the total work of the hip joint was the greatest during rearfoot landing. Conclusion: These results suggest that the energy absorption strategy was changed during rearfoot landing compared with forefoot landing according to lower-extremity joint kinematics and kinetics.

• 한국운동역학회지
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• 제25권2호
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• pp.231-240
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• 2015

Objective : This study is for providing data about men's functional sport underpants. It provides the fundamental data of biomechanics by measuring and analyzing the functionality of various underpants using infrared thermal image camera. Method : Then author drew a conclusion based on the final analysis of 965 questionnaire survey results about issues on men's functional sport underpants after discarding invalid questionnaires, as following. Change in body temperature while wearing functional underpants compared to general briefs or boxer pants showed lower temperature by approximately 1~2 degrees Celsius. In the case of general underpants, wearer sweats and feels hotter due to the friction of penis, scrotum and thigh. However functional sport functional underpants improved this issue with ergonomic 3D design by putting penis towards the lower part of the abdomen(below the navel) while putting the scrotum comfortably on the testicles, which enables to make room between the penis, scrotum and thigh of a wearer. Results : This was analyzed to lower the temperature of penis and scrotum. The survey results about the quality of functional underpants showed that 78% of the respondents felt comfortable while driving; 68.5% replied that frictional heat decreased while working out; 78.7% felt less sweat and humidity; 81.7% replied as highly wearable and comfortable; 77.1% replied functional sport underpants were the most comfortable in routine lives or in workout times. Putting all such results together, it is possible to conclude that functional sport is an excellent product. Conclusion : This can be evaluated as an excellent functional sport underpants, towards the penis abdomen (under the navel) in 3D human engineering design, by the scrotum to wearing to be easier to scrotum of pocket, the penis and scrotum and thighs were separated and analyzed with a function that will lower the body temperature of the penis and scrotum.

• 한국전문물리치료학회지
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• 제6권1호
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• pp.23-34
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• 1999

The purposes of this study were to investigate biomechanical variables of the lumbar spine for women who enjoy recreational exercises regularly, and to determine the factors that influence these variables. These variables were determined by the X-ray pictures of the lumbar area of 80 housewives who visited the department of rehabilitation at the Y Hospital from October 1997 to March 1998. The sacral inclination angle, the sacrohorizontal angle, the lumbosacral joint angle, and the lumbar lordotic angle were analysed. The t-test, correlation analysis, and multiple regression analysis were used to determine the significant differences and relationships among variables. The result were as follows: 1) There was a significant difference in the sacral inclination angle (p<0.01), the sacrohorizontal angle (p<0.05) and the lumbar lordotic angle (p<0.05) between the bilateral and the unilateral exercise group. 2) With the sacral inclination angle, the sacrohorizontal angle, the lumbosacral joint angle and the lumbar lordotic angle, correlation was found between the sacral inclination angle and the sacrohorizontal angle (p<0.01), the sacral inclination angle and the lumbosacral joint angle (p<0.05), the sacral inclination angle and the lumbar lordotic angle (p<0.05), and the sacrohorizontal angle and the lumbosacral joint angle (p<0.01). 3) In the bilateral exercise group, the sacral inclination angle correlated with age (p<0.01). The sacrohorizontal angle correlated with age (p<0.01) and exercise time (p<0.01). The lumbar lordotic angle correlated with age (p<0.05) and exercise duration (p<0.05). In the unilateral exercise group, the sacral inclination angle correlated with age (p<0.01), while the sacrohorizontal angle correlated with age (p<0.01) and exercise duration (p<0.05). The lumbar lordotic angle correlated with age (p<0.05).

• 한국운동역학회지
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• 제15권1호
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• pp.127-142
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• 2005

The purpose of this study was to analysis biomechanics of the lower extremities injury the heights(40cm, 60cm, 80cm) of jump box as performed depth jump motion by 6 females aerobic athletes and 6 non-experience females students. The event of depth jump were set to be drop, landing and jump. The depth jump motions on the force plate were filmed using a digital video cameras, and data were collected through the cinematography and force plate. On the basis of the results analyzed, the conclusions were drawn as follows: 1. The landing time of skill group was shorter than unskill group at 40cm, 60cm drop height during drop-landing-jump phase especially. The landing time of 60cm drop height was significant between two group(p<.05). 2. The peak GRF of sagittal and frontaI direction following drop height improve was variety pattern and the peak vertical force of 40cm drop height was significantly(p<.05). 3. The magnitude of peak passive force was not increase to change the drop height. 4. The peak passive forces was significant at 40cm drop height between two groups(p<.05)

• 한국운동역학회지
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• 제15권2호
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• pp.1-10
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• 2005

G. B. LEE, A. S. GWON, The Research for Using methodof GRF (Ground Reaction Force) on Rotational Movement in Arabesque. Korean Journal of Sport Biomechanics, Vol. 15, No. 2, pp.1-10, 2005. As, in relation to all movements of a human being, the movements such as mutually walking, running, rotating, and jumping are attained endlessly through the ground amid the interaction with the ground, in terms of the harmonious movement of the upper limbs and the lower limbs, related to the basic movement in ballet, the type of a movement depends on the size and direction of the force that presses down the ground (Fz, Fx, Fy) amid the interaction with the ground. Therefore, aiming to correctly and efficiently perform a rotational movement in Arabesque, this study analyzed factors of the force manifestation through GRF (Ground Reaction Force), by dividing into preparing, stepping, standing, rotating, and finishing stages (events (1) ${\sim}$ (5)), targeting the subjects of 4 elite female students who majored in ballet. 1. At the No.5 position of the preparing stage, It is necessary that support the ground with left and right foot balance, 2. As the stepping stage is the phase ranging from the event (2), in which a plie movement of bending a knee is started, to the event (3) of stretching a knee, Rebunding motion is not good, and One have a position with ankle and knee flextion condition in order to stretch strengthly in event (3) position 3. At the event (1) position, It is necessary that exert the Fz reaction force at the event (3) position. Because large stretch force help to have a toe on position easily and show a active motion 4. In order to have a stand and rotation motion smoothly, One need a muscle strength training for ankle extension, knee extension, control horizental force

• 한국운동역학회지
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• 제20권1호
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• pp.91-99
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• 2010

The purpose of this study was to the kinetic variables effects from the use of arch support inserts on low-arched people. We selected 10 people for the research and separated them into 2 groups, 5 people for the normal arched group and 5 people for the low arched group. Each group wear shoes which have a 3 step convertible arch support (level 0, level 2, level 5) and we measured their foot pressure and 3D motion analysis data. As a result, we found that the mean pressure at the heel of the low arched group was decreased when using the arch supports. The arch support induced the correct grounding area for the foot and dispersion of foot pressure. 3D motion analysis found that as the height of the arch support was increased, the movement of the Y-axis(inversion-eversion) was increased to relieve the shock to the heel. The arch support insert limited the range of motion(ROM) of the Z-axis(abduction-adduction) of the low arched person's ankle joint and prevented ankle injury caused by the excessive eversion when walking. Low arched people are seen to be easily tired due to the ineffective shock absorption of the knees and abnormal walking motion. In order to improve the problems, a 3 step convertible arch support(level 5) insert would improve the low-arched people's walking ability. In other words, the low arched people should be expected to walk as well as normal arched people when they wear shoes with the arch support insert.

• International Journal of Vascular Biomedical Engineering
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• 제2권1호
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• pp.11-16
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• 2004

Both flow visualizations and computational fluid dynamics were performed to determine hemodynamics in a total cavopulmonary connection (TCPC) model for surgically correcting congenital heart defects. From magnetic resonance images, an anatomically correct glass model was fabricated to visualize steady flow. The total flow rates were 4, 6 and 8L/min and flow rates from SVC and IVC were 40:60. The flow split ratio between LPA and RPA was varied by 70:30, 60:40 and 50:50. A pressure-based finite-volume software was used to solve steady flow dynamics in TCPC models. Results showed that superior vena cava(SVC) and inferior vena cava(IVC) flow merged directly to the intra-atrial conduit, creating two large vortices. Significant swirl motions were observed in the intra-atrial conduit and pulmonary arteries. Flow collision or swirling flow resulted in energy loss in TCPC models. In addition, a large intra-atrial channel or a sharp bend in TCPC geometries could influence on energy losses. Energy conservation was efficient when flow rates in pulmonary branches were balanced. In order to increase energy efficiency in Fontan operations, it is necessary to remove a flow collision in the intra-atrial channel and a sharp bend in the pulmonary bifurcation.

• The Journal of Advanced Prosthodontics
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• 제5권4호
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• pp.409-415
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• 2013

PURPOSE. The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures. MATERIALS AND METHODS. A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region. RESULTS. A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. CONCLUSION. Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region.