• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.215-219
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• 2003

In this paper, we generate a trajectory minimized the energy gait of a biped robot for walking a staircase using genetic algorithms and apply to the computed torque controller for the stable dynamic biped locomotion. In the saggital plane, a 6 degree of freedom biped robot that model consists of seven links is used. In order to minimize the total energy efficiency, the Real-Coded Genetic Algorithm (RCGA) is used. Operators of genetic algorithms are composed of a reproduction, crossover and mutation. In order to approximate the walking gait, the each joint angle is defined as a 4-th order polynomial of which coefficients are chromosomes. Constraints are divided into equality and inequality. Firstly, equality constraints consist of position conditions at the end of stride period and each joint angle and angular velocity condition for periodic walking. On the other hand, inequality constraints include the knee joint conditions, the zero moment point conditions for the x-direction and the tip conditions of swing leg during the period of a stride for walking a staircase.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.265-272
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• 2001

The human arm is modeled by three rigid bodies(the upper arm, the forearm and the hand)with seven degree of freedom(three in the shoulder, two in the elbow and two in the wrist). The objective of this work is to present a method to determine the three-dimensional kinematics of the human elbow joint using a magnetic tracking device. Euler angle were used to determine the elbow flexion-extension, and the pronation-supination. The elbow motion for the various driving conditions is measured through the driving test using a simulator. Discomfort levels of elbow joint motions were obtained as discomfort functions, which were based on subjects' perceived discomfort level estimated by magnitude estimation. The results showed that the discomfort posture of elbow joint motions occurred in the driving motion.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.787-796
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• 1995

A man model is a useful design tool for the evaluation of man machine systems and products. An arm reach trajectory prediction for such a model will be specifically useful to present human activities and, consequently, could increase the accuracy and reality of the evaluation. In this study, a three-dimensional reach trajectory prediction model was developed using an inverse kinematics technique. The upper body was modeled as a four link open kinematic chain with seven degrees of freedom. The Resolved Motion Method used for the robot kinematics problem was used to predict the joint movements. The cost function of the perceived discomfort developed using the central composite design was also used as a performance function. This model predicts the posture by moving the joints to minimize the discomfort on the constraint of the end effector velocity directed to a target point. The results of the pairwise t-test showed that all the joint coordinates except the shoulder joint's showed statistically no differences at .alpha. = 0.01. The reach trajectory prediction model developed in this study was found to accurately simulate human arm reach trajectory and the model will help understand the human arm reach movement.

• Proceedings of the ESK Conference
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• 1997.04a
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• pp.100-106
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• 1997

The purpose of this study is to measure perceived joint discomfort in the seated and standing position, and to provide a ranking system of joint discomfort measured in this study. Seven male subjects with no history of musculo-skeletal disorders participated in the experiment. Their physical characteristics were: age -$27.6 {\pm}1.8$ years, stature -$171.0 {\pm}5.5cm$, and body weight -$66.4{\pm}9.3kg$. The results showed that perceived joint discomfort was different depending on the human body joints involved in motion and their movement directions, which imply that the human body motions should be classified intoseveral distinct classes that need to be assigned different weights of postural stress. In the seated postion, the hip movement was the most stressful, the back was the second, and the shoulder was the third. Similarly, in standing postures, the hip was given the highest ranking, followed by the back, and the wrist.

• Journal of the Ergonomics Society of Korea
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• v.15 no.1
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• pp.39-52
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• 1996

This paper measured the range of arm joint motion for Korean 54 males in twenties. The range of the arm joint motion of the subjects was measured directly using Goniometer and protractor. The number of the static and the dynamic anthropometric variables are seven and thirteen, respectively. The anthropometric data are analyzed by basic statistical analysis (four group), correlation analysis and regression analysis using commercial SAS program. The results of analysis are compared with American students anthropometric data by Laubach(1978). Thin subjects have larger movement angle as wrist flexion, wrist abduction, elbow flexion, and elbow wupination and have smaller as wrist adduction and shoulder flexion. Fat subjects have larger movement angle as shoulder flexion and are smaller wrist abduction, elbow flexion, pronation, shoulder extension, shoulder adduction, shoulder abduction, and shoulder medial rotation Korean are more flexible than American in wrist and ranges of elbow flexion and elbow rotation. The shoulder movement is similar to that of American, but shoulder flexion is less flexible.

• Journal of the Ergonomics Society of Korea
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• v.26 no.1
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• pp.19-27
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• 2007

Despite the widespread use of laterally wedged insoles for patients with knee osteoarthritis and medially wedged insoles for controlling rearfoot pronation, an understanding of the effects of wedged insoles was limited and sometimes controversial. The objective of this study was to evaluate the effect of wedged insoles on the kinematics and kinetics of normal gait. Ten male subjects without history of lower limb disorders were recruited. Each subject performed four gait cycles under each of seven conditions; shod with 5$^{\circ}$, 8$^{\circ}$ and 15$^{\circ}$, 8$^{\circ}$ and 15$^{\circ}$ laterally wedged insoles. In order to determine statistical differences among seven conditions, the measured temporal spatial variables, angular displacements, joint moments, and ground reaction forces were compared with a one-way analysis of variance. Some significant changes induced by wedged insoles were apparent in joint moments and ground reaction forces. The medially wedged insole increased the laterally directed ground reaction force and varus moments at the ankle force and varus moments at the ankle and the knee.

• Structural Engineering and Mechanics
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• v.82 no.1
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• pp.69-79
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• 2022

This paper discusses the field testing of two single-span double-tee girder (DTG) bridges in South Dakota to determine live load distribution factors (LLDFs) and the dynamic load allowance (IM). One bridge had seven girders and another had eight girders. The longitudinal girder-to-girder joints of both bridges were deteriorated in a way that water could penetrate and the joint steel members were corroded. A truck traveled across each of the two bridges at five transverse paths. The paths were tested twice with a crawl speed load test and twice with a dynamic load. The LLDFs and IM were determined using strain data measured during the field tests. These results were compared with those determined according to the AASHTO Standard and the AASHTO LRFD specifications. Nearly all the measured LLDFs were below the AASHTO LRFD design LLDFs, with the exception of two instances: 1) An exterior DTG on the seven-girder bridge and 2) An interior DTG on the eight-girder bridge. The LLDFs specified in the AASHTO Standard were conservative compared with the measured LLDFs. It was also found that both AASHTO LRFD and AASHTO Standard specifications were conservative when estimating IM, compared to the field test results for both bridges.

• Journal of Veterinary Clinics
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• v.18 no.3
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• pp.243-248
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• 2001

Radiographic findings of degenerative joint disease (DJD) in the coxofemoral joints were studied in 108 dogs referred to Veterinary Medical Teaching Hospital, College of Veterinary Medicine, Seoul National University. Radiographic findings were identified with a extended ventrodorsal projection. Clinical signs such as pain in the affected joint, exercise intolerance, lameness, crepitation on flexion and extension of the joint and decreased range of motion, were shown in 40% and radiographic changes of bilateral coxofemoral joints were identified in 69% of a group of dogs. There are no sex predilections. Thirty-seven dogs were diagnosed as canine hip dysplasia (CHD; 10 cases), avascular necrosis of the femoral head (Legg-Calves-Perthes disease [LCPD]; 12 cases), fracture of the acetabulum (1 case), luxation(10 cases) and subluxation (15 cases), however, luxation and subluxation were identified in 11 dogs affected with CHD and LCPD. Causes of DJD in others (71case) were not identified. Radio-graphic findings identified included osteophyte formation at the attachment of the joint capsule (70%), sclerosis of the subchondral bone of the cranial acetabular edge (47%), remodeling of the femoral head (34%), thickening of the femoral neck(31%), perichondral osteophyte formation (31%), joint laxity (30%) and so on. All of the dogs diagnosed as CHD were large breed such as Retriever, Germain Shepherd, and Weimaraner and their age was under 1 year. This condition occurred bilaterally in 70% of affected animals. Dogs diagnosed as LCPD were young (under 1 year), small breed dogs. The incidence of LCPD is greater in Yorkshire Terrier, Miniature Pinscher and Poodle. This condition occurred unilaterally in 67% of affected animals. Clinical signs of dogs with unknown cause were shown in 15% and this condition occurred bilaterally in 75% of affected animals. Radiographic findings varied with patient's age and breed, however, the most common finding was osteophyte formation at the attachment of the joint capsule.

• International Journal of Highway Engineering
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• v.9 no.3
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• pp.101-110
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• 2007

Joint Spacing of Jointed Concrete Pavement has been uniformly designed and constructed as six-meter in Korea. However, engineering backgrounds to show the appropriateness of six-meter Joint Spacing has not been provided. In the on-going reseach of the development of Korea Pavement Reseach Program(KPRP), the optimum Joint Spacing is suggested as 6 to 8 meters according to the regional climatic conditions based on the mechanical-empirical analysis of short-term and long-term pavement distress. This study is a part of the investigation on the adequateness of Joint Spacing design specification suggested in KPRP. Joint Spacing was design and constructed as seven-meter Joint Spacing suggested as design specification in Korea Reseach Program(KPRP) and monitored the Load Transfer Efficiency(LTE), Random crack and compared with those of adjacent $6{\sim}7$ meter Joint Spacing concrete section.

• Clinics in Shoulder and Elbow
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• v.27 no.2
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• pp.247-253
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• 2024

Acromioclavicular (AC) joint dislocations frequently co-occur with intra-articular glenohumeral pathologies. Few comprehensive studies have focused on labral tears specifically associated with AC joint trauma. This systematic review will address this gap. A comprehensive electronic search was conducted across PubMed, Cochrane Library, and Google Scholar (pages 1-20) spanning from 1976 to May 19, 2023. Seven studies met the inclusion criteria for this systematic review, consisting of three retrospective studies and four case series. These studies collectively involved 1,044 patients, of whom 282 had concomitant labral lesions. The pooled prevalence of intra-articular labral injuries associated with acute AC joint dislocation was 27%. The prevalence of these labral lesions varied significantly between studies, ranging from 13.9% to 84.0% of patients, depending on the study and the grade of AC joint dislocation. Various types of labral tears were reported, with superior labrum anterior to posterior (SLAP) lesions being the most common. The prevalence of SLAP lesions ranged from 7.2% to 77.4%, with higher grades of AC joint dislocations often associated with a higher prevalence of SLAP tears. Moreover, grade V dislocations exhibited a complete correlation with SLAP tears. The studies yielded contradictory findings regarding older age and higher grades of AC joint dislocation as risk factors for concurrent labral lesions. This review underscores the frequent association between labral lesions and AC joint dislocations, particularly in cases of lower-grade injuries. Notably, SLAP lesions emerged as the predominant type of labral tear.