• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.268-273
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• 2000

Velocity-dependent increase in tonic stretch reflexes is one of the prominent characteristics of spasticity. It is very important to evaluate spasticity objectively and quantitatively before and after treatment for physicians. An accurate quantitative biomechanical evaluation for the spasticity which is caused by the disorder of central nervous system is made in this study. A sudden leg dropper which is designed to generate objective testing environment at every trial gives very effective environment for the test. Kinematic data are archived by the 3-dimensional motion analysis system($Elite^{(R)}$, B.T.S., Italy). Kinematic data are angle and angular velocity of lower limb joints, and length and lengthening velocity of lower limb muscle. A program is also developed to analyze the kinematic data of lower limb, contraction and relaxation length of muscles, and dynamic EMG data at the same tim. To evaluate spasticity quantitatively, total 31 parameters extracted from goniogram, EMG and muscle model are analyzed. Statistical analysis are made for bilateral correlations for all parameters. The described instrumentation and parameters to make quantitative and objective evaluation of spasticity shows good results.

• 한국운동역학회지
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• 제28권1호
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• pp.61-67
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• 2018

Objective: The human body is often modelled as a spring-mass system. Lower extremity stiffness has been considered to be one of key factor in the performance enhancement of running, jumping, and hopping involved sports activities. There are several different classification of lower extremity stiffness consisting of vertical stiffness, leg stiffness, joint stiffness, as well as muscle and tendon stiffness. The primary purpose of this paper was to review the literature and describe different stiffness models and discuss applications of stiffness models while engaging in sports activities. In addition, this paper provided a current update of the lower extremity literature as it investigates the relationships between lower extremity stiffness and both functional performance and injury. Summary: Because various methods for measuring lower extremity stiffness are existing, measurements should always be accompanied by a detailed description including type of stiffness, testing method and calculation method. Moreover, investigator should be cautious when comparing lower extremity stiffness from different methods. Some evidence highlights that optimal degree of lower extremity stiffness is required for successful athletic performance. However, the actual magnitude of stiffness required to optimize performance is relatively unexplored. Direct relationship between lower extremity stiffness and lower extremity injuries has not clearly been established yet. Overall, high stiffness is potentially associate risk factors of lower extremity injuries although some of the evidence is controversial. Prospective injures studies are necessary to confirm this relationship. Moreover, further biomechanical and physiological investigation is needed to identify the optimal regulation of the lower limb stiffness behavior and its impact on athletic performance and lower limb injuries.

• Clinics in Shoulder and Elbow
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• 제24권3호
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• pp.141-146
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• 2021

Background: The purpose of the present study was to determine how long superior screws alone or in combination with posterior placement of metaglene screws protruding and penetrating into the scapular spine in reverse total shoulder arthroplasty affect the strength of the scapular spine in a fresh cadaveric scapular model. Methods: Seven fresh cadaver scapulas were allocated to the control group (short posterior and superior screws) and seven scapulars to the study group (spine base fixation with a four long screws, three with both long superior and long posterior screws). Results: The failure load was lower in the spine fixation group (long screw, 869 N vs. short screw, 1,123 N); however, this difference did not reach statistical significance (p>0.05). All outside-in long superior or superior plus posterior screws failed due to scapular spine base fracture; failures in the short screw group were due to acromion fracture. An additional posterior outside-in screw failed to significantly decrease the failure load of the acromion spine. Conclusions: The present study highlights the significance of preventing a cortical breach or an outside-in configuration when a superior or posterior screw is inserted into the scapular spine base.

• Clinics in Shoulder and Elbow
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• 제25권4호
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• pp.282-287
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• 2022

Background: Muscular forces drive proximal humeral fracture deformity, yet it is unknown if arm position can help mitigate such forces. Our hypothesis was that glenohumeral abduction and humeral internal rotation decrease the pull of the supraspinatus and subscapularis muscles, minimizing varus fracture deformity. Methods: A medial wedge osteotomy was performed in eight cadaveric shoulders to simulate a two-part fracture. The specimens were tested on a custom shoulder testing system. Humeral head varus was measured following physiologic muscle loading at neutral and 20° humeral internal rotation at both 0° and 20° glenohumeral abduction. Results: There was a significant decrease in varus deformity caused by the subscapularis (p<0.05) at 20° abduction. Significantly increasing humeral internal rotation decreased varus deformity caused by the subscapularis (p<0.05) at both abduction angles and that caused by the supraspinatus (p<0.05) and infraspinatus (p<0.05) at 0° abduction only. Conclusions: Postoperative shoulder abduction and internal rotation can be protective against varus failure following proximal humeral fracture fixation as these positions decrease tension on the supraspinatus and subscapularis muscles. Use of a resting sling that places the shoulder in this position should be considered.

• Animal Bioscience
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• 제36권9호
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• pp.1393-1402
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• 2023

Objective: In this study effects of three types of beddings on broiler leg health and bone biomechanics were evaluated. Methods: A total of 504 male chicks (Ross 308) were randomly placed on three beddings (4 replicates/group; 42 birds/pen), zeolite-added litter (ZL), plastic-grid flooring (PF), and wood shavings (WS). On day 42, chickens were weighed, slaughtered, and samples (bone, muscle, and drumstick) were collected. Bones were subjected to leg health tests, morphometric measurements, biomechanical testing, and ash analysis. Results: Broilers in PF and WS groups showed higher live weight than the ZL group (p<0.001), and the incidence of tibial dyschondroplasia (TD) and varus valgus deformity due to distal bending was significantly higher in PF (p<0.001). Multinomial logistic regression showed that bedding has a significant (p = 0.038) contribution toward the development of TD. Tibial strength (p = 0.040), drumstick width (p = 0.001), and total femur and epiphyseal ash contents (p = 0.044, 0.016) were higher in the ZL group. Chicken live weight was correlated with tibial length and weight (r = 0.762, 0.725). Conclusion: Flooring and the type of bedding material directly affect broiler bone length, strength and leg health. Plastic bedding improves the slaughter weight of chickens on the expense of leg deformities, and zeolite litter improves leg health and bone strength.

• 한국운동역학회지
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• 제19권1호
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• pp.149-157
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• 2009

본 연구의 목적은 한국의 대표적인 배드민턴화(A Type)와 외국 배드민턴 브랜드제품(B Type)의 생체역학적인 변인들을 비교함으로서 한국제품의 착화감과 기능을 향상시켜 세계적인 수준의 배드민턴화 개발에 일조하는데 목적을 두었다. 분석변인들로는 동작 간 신발 안에서 발의 상대적인 움직임, 지면반력과 압력분포, 아웃솔의 마찰력등을 분석하였다. 또한 17명의 피험자를 통한 주관적인 착화감과 기능에 관련된 주관적인 실험이 실시되었다. A Type 배드민턴화의 경우 높은 뒤꿈치의 위치와 밋밋한 뒷굽의 형태로 신발 안에서 뒤꿈치를 잘 잡아주지 못하는 것으로 나타났다. 따라서 A Type 배드민턴화가 약 40%이상 발이 신발 안에서의 미끄러짐 현상이 일어났으며 충격력의 형태나 최대 압력분포도 높게 나타났다. Type A 신발의 경우 Type B와 같이 자연스러운 굴곡이 발의 볼쪽에서 일어나지 않고 전족부근에서 일어났다. 요약을 하면, 두 신발 간에 몇몇 차이점들이 발견되었고 A Type 배드민턴화의 기능을 향상하기 위해서 보완가능 요인들이 제시되었다.

• 한국의류산업학회지
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• 제18권4호
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• pp.520-530
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• 2016

This research aims to propose an ergonomic design process for hip protector based on previous studies, existing products, multidisciplinary experts opinion, and wearing test. The elderly are more likely to suffer a hip fracture when they fall due to their physical changes in skeletal form, muscle quantity, bone density, and joint movement. A hip protector is an effective product to prevent hip fractures in the elderly but it also has a problem in that it is uncomfortable. Therefore there is a high chance that it won't be able to prevent hip fractures properly. Since the comfort of a hip protector is one of the most critical elements in preventing a hip fracture, we need to keep improving the hip protector for mobility and usability. Based on the previous studies and limitations of current hip protector products, we need to come up with an optimal design for the Korean elderly. First, knowledge has to be built relating to the ergonomic design of the hip protector considering body shape and size analysis using 3D-scan data, and biomechanical analysis on hip fracture. Second, we need to develop a design process including hip protector pattern design, and wearing evaluation with virtual system. Third, we suggest to reevaluate and verify the design procedure from impact evaluation using testing simulator, virtual evaluation of impact, to wearing comfort and usability evaluation. This design process presented in this study would be expected to contribute to the development of ergonomic hip protector which is suitable for the Korean elderly.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.280-286
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• 2019

본 연구는 발의 피로와 통증을 줄이고 발의 정상적인 기능을 유지해주는 기능적 인솔 적용 유무가 노인 보행 시 하지의 생체 역학적 변인 및 패턴에 미치는 영향을 규명하고자 하였다. 본 연구의 대상자는 10명(연령, 73.2 세: 신장, 152.1 cm: 체중, 59.4 kg)이며, 기능적 인솔 착용과 비 착용 시의 보행을 분석하였다. 보행분석은 퀄리시스 시스템 (Qualisys system)으로 촬영 후 비쥬얼 3D (Visual-3D)로 분석하였다. 그 결과, 기능적 인솔을 착용했을 경우, 보장과 유각기 속도가 유의미하게 증가하였다 (p<.05). 또한 하지의 신전 모멘트가 입각기에서 유의미하게 증가하였다 (p<.05). 본 연구 결과 기능적 인솔은 노인의 보행 안정성을 향상시는 효과가 있었다. 그러나 이 연구의 결과를 일반화하기 위해서는 더 많은 대상자들을 통해 보다 많은 정량적 자료를 축적할 필요가 있으며, 대상자들에게 오랜 시간동안 인솔을 사용하게 한 후 보행변인 및 패턴의 변화를 검토하는 연구가 추후 이뤄져야 할 것으로 판단된다.

• 대한의용생체공학회:의공학회지
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• 제21권3호
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• pp.303-309
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• 2000

본 연구에서는 중추신경계 질환에 의해 발생하는 경직을 정밀하고 정량적으로 평가하기 위하여 생체역학적 측면에서 실험 및 분석을 수행하였다. 객관적인 실험환경을 만족시키기 위해 기존에 검사자가 손으로 수행하던 방식을 개발된 진자실험 장치를 통하여 동일한 방법과 높이가 재현될 수 있도록 하였다. 하지의 진자 운동에서 발생되는 운동 형상학적 데이터들은 3차원 동작 분석장비(Elite. B.T.S. Italy)를 사용하여 측정하였으며, 경직과 관련된 하지의 각도, 각속도 변수에 대한 분석이 수행되었다. 진자 운동시 하지의 운동형상학적 데이터, 근육들의 길이변화와 변화 속도, 동적 근전도신호 등을 동시에 고려할 수 있는 프로그램을 제작하였다. 또한 기존의 분석보다 다양한 각도에서 경직의 정량적 평가가 가능하도록 14개의 새로운 변수를 도출하여 정량적 평가를 위한 총 26개의 변수에 대한 상호 상관성을 검토하였다. 새롭게 제시된 검사방식과 새로운 변수를 통하여 정밀하고 객관적인 경직 판정의 가능성을 제시하였다.

• Restorative Dentistry and Endodontics
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• 제39권4호
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• pp.265-269
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• 2014

Objectives: To evaluate the effect of different ultrasonic tip designs on intraradicular post removal. Materials and Methods: The crowns of forty human canine teeth were removed, and after biomechanical preparation and filling, the roots were embedded in acrylic resin blocks. The post spaces were made, and root canal molding was performed with self-cured acrylic resin. After casting (Cu-Al), the posts were cemented with zinc phosphate cement. The specimens were randomly separated into 4 groups (n = 10), as follows: G1 - no ultrasonic vibration (control); G2 - ultrasonic vibration using an elongated cylindrical-shaped and active rounded tip; G3 - ultrasonic vibration with a flattened convex and linear active tip; G4 - ultrasonic vibration with active semicircular tapered tip. Ultrasonic vibration was applied for 15 seconds on each post surface and tensile test was performed in a Universal Testing Machine (Instron 4444 - 1 mm/min). Results: G4 presented the highest mean values, however, with no statistically significant difference in comparison to G3 (p > 0.05). G2 presented the lowest mean values with statistically significant difference to G3 and G4 (p < 0.05). Conclusions: Ultrasonic vibration with elongated cylindrical-shaped and active rounded tip was most effective in reducing force required for intraradicular post removal.