• 한국운동역학회지
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• 제32권1호
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• pp.9-16
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• 2022

Objective: The purpose of this study was to investigate how the chronic ankle instability affects postural control during forward jump landing. Method: 20 women with chronic ankle instability (age: 21.7 ± 1.6 yrs, height: 162.1 ± 3.7 cm, weight: 52.2 ± 5.8 kg) and 20 healthy adult women (age: 21.8 ± 1.6 yrs, height: 161.9 ± 4.4 cm, weight: 52.9 ± 7.2 kg) participated in this study. For the forward jump participants were instructed to stand on two legs at a distance of 40% of their body height from the center of force plate. Participants were jump forward over a 15 cm hurdle to the force plate and land on their non-dominant or affected leg. Kinetic and kinematic data were obtained using 8 motion capture cameras and 1 force plates and joint angle, vertical ground reaction force and center of pressure. All statistical analyses were using SPSS 25.0 program. The differences in variables between the two groups were compared through an independent sample t-test, and the significance level was to p < .05. Results: In the hip and knee joint angle, the CAI group showed a smaller flexion angle than the control group, and the knee joint valgus angle was significantly larger. In the case of ankle joint, the CAI group showed a large inversion angle at all events. In the kinetic variables, the vGRF was significantly greater in the CAI group than control group at IC and mGRF. In COP Y, the CAI group showed a lateral shifted center of pressure. Conclusion: Our results indicated that chronic ankle instability decreases the flexion angle of the hip and knee joint, increases the valgus angle of the knee joint, and increases the inversion angle of the ankle joint during landing. In addition, an increase in the maximum vertical ground reaction force and a lateral shifted center of pressure were observed. This suggests that chronic ankle instability increases the risk of non-contact knee injury as well as the risk of lateral ankle sprain during forward jump landing.

• Design & Manufacturing
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• 제13권4호
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• pp.23-27
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• 2019

People's interest in the environmental problems of the Earth is growing as they come to the modern world, and research is being actively conducted on how to protect the environment. As a result, the automobile industry, one of the causes of environmental pollution, is also affected. Therefore, research is being conducted to improve the fuel economy and light weight of cars, development of pollution-free cars such as electric cars, and aluminium materials that are lighter than ordinary steel sheets and easier to recycle are gaining attention. In this experiment, the material was formed to form a form of aluminium and the material reduction rate of the side wall of the foam was tested according to the amount of side wall. The material used in the experiment was A3003-O, which is less plastic than normal steel plates, but has excellent corrosion resistance, plasticity and weldability compared to aluminium materials, but has poor tensile strength. For tensile testing, a certain array of Forming Shapes was molded and the height of the Forming was set to 5mm, and the height of the Forming was 4.7mm, indicating that the difference between the first 5mm Forming and the height was not large. In addition, the material reduction rate was tested by giving 15, 0, and -0.15 teas, respectively, and was found to be valuable as a product only for -0.15.

• 한국운동역학회지
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• 제29권4호
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• pp.255-261
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• 2019

Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.

• 한국운동역학회지
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• 제31권2호
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• pp.113-118
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• 2021

Objective: The purpose of this study was to investigate differences of landing strategy between people with or without chronic ankle instability (CAI) during double-leg drop landing. Method: 34 male adults participated in this study (CAI = 16, Normal = 18). Participants performed double-leg drop landing task on a 30 cm height and 20 cm horizontal distance away from the force plate. Lower Extremities Kinetic and Kinematic data were obtained using 8 motion capture cameras and 2 force plates and loading rate was calculated. Independent samples t-test were used to identify differences between groups. Results: Compared with normal group, CAI group exhibits significantly less hip internal rotation angle (CAI = 1.52±8.12, Normal = 10.63±8.44, p = 0.003), greater knee valgus angle (CAI = -6.78±5.03, Normal = -12.38 ±6.78, p = 0.011), greater ankle eversion moment (CAI = 0.0001±0.02, Normal = -0.03±0.05, p = 0.043), greater loading Rate (CAI = 32.65±15.52, Normal = 18.43±10.87, p = 0.003) on their affected limb during maximum vertical Ground Reaction Force moment. Conclusion: Our results demonstrated that CAI group exhibits compensatory movement to avoid ankle inversion during double-leg drop landing compared with normal group. Further study about how changed kinetic and kinematic affect shock absorption ability and injury risk in participants with CAI is needed.

• 한국통신학회논문지
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• 제26권12A호
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• pp.2019-2026
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• 2001

본 논문에서는 동적인 임계화 방법과 코호넨 알고리즘을 이용하여 차량 번호판을 인식하는 알고리즘을 제안하였다. 일반적으로 차량 영상에서 번호판 영역은 문자와 배경의 자기가 뚜렷하게 구별되고, 일정한 크기 비율을 가지면서 다른 영역보다 밀집 비율이 높게 나타난다. 본 논문은 이런 차량 영상의 속성을 이용하여 차량 영상에 대해 동적인 임계화를 수행하였고 밀집 비율을 계산하여 번호판 영역을 추출하였다. 추출된 번호판에서 문자와 숫자를 포함하는 특징 영역을 추출하기 위해 코호겐 알고리즘을 적용한 윤곽선 추적 방법을 이용하였다. 번호판의 문자와 숫자들은 코호넨 알고리즘을 이용하여 인식하였다. 코호넨 알고리즘은 윤곽선에서 생성되는 잡음을 최대한으로 줄여주는 특성을 가진다. 다양한 환경에서 촬영된 80장의 영상에 대하여 인식 실험을 수행한 결과, 제안된 방법이 차량 번호판의 인식에 우수한 성능을 보였다.

• 대한족부족관절학회지
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• 제17권2호
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• pp.143-149
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• 2013

Purpose: Open reduction and internal fixation of calcaneal fracture using plate has been used. While numerous plates have been manufactured, most of the conventional plates are designed for westerners, realistically the size is larger for Korean. The domestic products, on the other hand, often have the undesirable screw holes and path. Therefore, we measured the radiologic parameter of Korean calcaneus for providing the plate and screw hole placements. Materials and Methods: We measured the outer lines and angles with over the 20 years old 291 females and 322 males. A: Length of inferior plane of calcaneus, B: Length of anterior plane of calcaneus, C: Length from line A to sinus tarsi, D: Length from line A to posterior point of posterior facet, E: Length from line A to calcaneal tuberosity, F: Length of posterior facet, G: Length from anterior point of line A to C, H: Length from line C to line D, a: Angle between A and B, b: Gissane angle, c: Bohler angle, d: Calcaneal pitch angle using Marosis m-view$^{(R)}$. Results: Mean A, B, C, D, E, F, G, H were 63.6, 26.4, 23.2, 43.7, 40.5, 26.9, 12.8, 18.1 mm. Mean a, b, c, d angle were 105.8, 122.4, 32.4, $20.5^{\circ}$. Male's calcaneus is significantly bigger than female's (p<0.001). Conclusion: AP calcaneus length 63.6 mm, maximal height 43.7 mm is considered to be helpful in making the Korean calcaneal plate.

• 한국지반공학회논문집
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• 제38권2호
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• pp.29-38
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• 2022

마찰 방향에 따른 전단 저항의 이방성을 지반 구조물에서 선택적으로 이용할 수가 있다. 예를 들어서, 축방향으로 하중을 가하는 깊은 기초, 소일 네일링, 타이백 등은 큰 전단 저항이 유발되므로 하중 전달 능력을 증가시키지만, 이와 반대로 말뚝 관입과 흙 시료 채취 등은 최소화된 전단 저항만 유발된다. 기존 연구는 뱀 비늘의 기하학적 형상과 유사한 표면 돌출부를 갖는 플레이트와 흙 경계면에서 유발되는 전단 저항 변화를 확인하였다. 본 논문에서는 표면 돌출부의 형상에 따른 경계면 마찰각의 변화를 정량적으로 평가하였다. 수정된 직접 전단 시험기를 이용하여 상대 밀도가 40%로 조성된 모래 시료에 대해 9개의 플레이트, 2개의 전단 방향(전단 시 돌출부 높이가 증가와 감소하는 방향), 그리고 3개의 초기 수직 응력(100kPa, 200kPa, 300kPa) 조건으로 총 51가지 경우를 실험 하였다. 실험 결과, 전단 응력은 돌출부 높이가 높을수록, 돌출부 길이가 짧을수록, 돌출부 높이가 증가하는 전단 방향에서 크게 나타났다.

• 한국산림과학회지
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• 제103권2호
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• pp.248-257
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• 2014

이 연구는 풍도목 근분의 구조형태적 특성을 파악하고, 풍향에 대응하는 수목뿌리의 발달 특성 및 수목의 지상부와 지하부 특성 간의 상관관계를 분석하고자 하는 목적으로 수행되었다. 이를 위해서 서울대학교 태화산 학술림에서 발생한 77 그루의 낙엽송과 24 그루의 잣나무 풍도목의 근분에 대한 현장조사를 실시하였다. 근분의 형태적 특성을 조사한 결과, 풍도목 근분은 타원형 혹은 원형의 평면형을 보이며, 측면에서 살펴보면 반 타원체의 형태를 보였다. 또한, 근분 내 뿌리의 발달 특성을 조사한 결과, 평균적으로 수목의 전도 방향에서 비전도 방향보다 뿌리의 개수가 더 많고, 뿌리 표면적이 더 큰 것으로 나타났다. 또한, 수목의 지상부와 지하부 특성 간의 선형상관관계를 조사한 결과, DBH는 수고보다 근분 크기와 뿌리 표면적에 대해 상대적으로 강한 선형적인 상관관계를 보였다. 이러한 상관관계 분석 결과를 토대로 상관관계가 뚜렷한 수목 지상부와 지하부 특성 간의 단순선형회귀식을 수립하였다.

• 대한한의학회지
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• 제33권2호
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• pp.1-10
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• 2012

Objectives: This study was aimed to investigate the effect of Bojungikgitang-gagambang (BJIG) on longitudinal bone growth in rats. Methods: The BJIG treated group (300 mg/kg) and the control group (vehicle) were administered orally twice daily for 4 days. To investigate the effects of BJIG we measured body weight gain. The bone growth effect was analyzed by measuring between fluorescent lines marked with tetracycline, which plays the role of fluorescent dye on the surface of the tibia. Tetracycline was intraperitoneally injected. The height of growth plates in the epiphyseal plate was measured. The expression of bone morphogenetic protein-2 (BMP-2) and insuline-like growth factor-1 (IGF-1) was investigated by immunohistochemistry. Results: BJIG caused a significant acceleration of longitudinal bone growth of $349.7{\pm}15.9{\mu}m/day$ compared to control ($319.8{\pm}21.4{\mu}m/day$). The height of overall growth plate was not significantly more compared to the control, but the size of cells in the proliferative zone and hypertrophic zone were. In the immunohistochemistry, BMP-2 and IGF-1 were expressed markedly in the proliferative or hypertrophic zone, respectively. Conclusions: BJIG stimulated the chondrocyte hypertrophy and chondrogenesis in the growth plate and directly increased the longitudinal tibia length of rats.

• Journal of Periodontal and Implant Science
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• 제54권2호
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• pp.108-121
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• 2024

Purpose: The aim of this study was to compare changes in soft and hard tissue and the histologic composition following early implant placement in sites with alveolar ridge preservation or spontaneous healing (SH), as well as implant performance up to 1 year after crown insertion. Methods: Thirty-five patients with either intact buccal bone plates or dehiscence of up to 50% following single-tooth extraction of incisors, canines, or premolars were included in the study. They were randomly assigned to undergo one of three procedures: deproteinized bovine bone mineral with 10% collagen (DBBM-C) covered by a collagen matrix (DBBM-C/CM), DBBM-C alone, or SH. At 8 weeks, implant placement was carried out, and cone-beam computed tomography scans and impressions were obtained for profilometric analysis. Patients were followed up after the final crown insertion and again at 1 year post-procedure. Results: Within the first 8 weeks following tooth extraction, the median height of the buccal soft tissue contour changed by -2.11 mm for the DBBM-C/CM group, -1.62 mm for the DBBM-C group, and -1.93 mm for the SH group. The corresponding height of the buccal mineralized tissue changed by -0.27 mm for the DBBM-C/CM group, -2.73 mm for the DBBM-C group, and -1.48 mm for the SH group. The median contour changes between crown insertion and 1 year were -0.19 mm in the DBBM-C/CM group, -0.09 mm in the DBBM-C group, and -0.29 mm in the SH group. Conclusions: Major vertical and horizontal ridge contour changes occurred, irrespective of the treatment modality, up to 8 weeks following tooth extraction. The DBBM-C/CM preserved more mineralized tissue throughout this period, despite a substantial reduction in the overall contour. All 3 protocols led to stable tissues for up to 1 year.