숏피닝 가공재의 저온 피로 강도 평가

박경동,권오헌 한국안전학회 2003 한국안전학회지 Vol.18 No.3

In this study, CT specimens were prepared from spring steel(SPS5) processed shot peening. The fatigue crack growth tests were carried out in the environment of the room temperature and low temperature at 25℃, -30℃, -50℃, -70℃ -100℃ and -150℃ in the range of stress ratio of 0.05 by means of opening mode displacement. The threshold stress intensity factor range ΔKth in the early stage of fatigue crack growth (Region Ⅰ) and stress intensity factor range ΔK in the stable of fatigue crack growth (Region Ⅱ) were decreased in proportion to descend temperature. It was shown that the fatigue resistance characteristics and fracture strength at low temperature are considerable higher than those of room temperature in the early stage and stable of fatigue crack growth region.

칼만증후군(Kallmann's Syndrome) 1례

김용성,백승훈,유경훈,구기선,형근영,김경년,조정구 圓光大學校 醫科學硏究所 1997 圓光醫科學 Vol.13 No.1-2

Kallmann's syndrome is the most common form of isolated gonadotropin deficiency, characterized by hypogonadotropic hypogonadism due to GnRH deficiency, delayed puberty and smelling difficulty. It occurs sporadic or familial pattern, and the mode of inheritence has not been fully documented. The defect in patient of Kallmann's syndrome occurs at suprapituitary level involving mechanism that regulate GnRH synthesis or release, so this syndrome classified as a secondary hypogonadotropic hypogonadism. The gonadotropin or pulsatile GnRH administration enable successful stimulation of spermatogenesis and fertility. We have experienced 1 patient with Kallmann's syndrome and presented with the review of the literature.

실업계 고등학생의 직업기초능력 향상을 위한 문제중심학습(PBL)의 효과

박동열,이성덕,김종오,조경희,강경심,박윤희,김대영 한국농업교육학회 2006 농업교육과 인적자원개발 Vol.38 No.4

21세기 지식기반사회는 전문지식뿐만 아니라 효율적인 직무 수행에 필요한 의사소통능력, 문제해결능력, 자기관리능력 및 직업의식 등의 직업기초능력이 강조되고 있다. 직업기초능력은 생의 어느 한 시기에 갑자기 이루어지거나 완성되는 l회적인 것이 아니라 개인의 생애단계에 따라 변화하고 발달하는 것이며 취업자뿐만 아니라 진학자에게도 잠재적으로 매우 중요한 요소이므로 실업계 고등학생의 직업기초능력 향상은 중요한 현안이라 할 수 있다. 이 연구는 여러 교수학습유형 중 실업계 고등학생의 직업기초능력 향상에 타당하리라 사료되는 문제 중심학습 모형(Problem-based learning model)을 선정, 이에 기초한 전문교과 수업을 실시하여 실업계 고등학생의 직업기초능력 향상에 기여할 수 있는지 실증적으로 분석하고자 하였다. 연구 목적 달성을 위해 「대학생의 직업기초능력 유형 검사도구(박동열, 2005)」를 실업계 고등학교 전문가 협의회를 통해 수정ㆍ보완, 이를 활용하여 실업계 고등학생의 직업기초능력을 파악하고, 문제중심학습 모형에 따른 실제 전문교과 수업을 통한 실업계 고등학생의 직업기초능력 향상 정도를 알아보기 위하여 농업계열, 공업계열, 상업계열, 가사ㆍ실업계열 4명의 현직 교사가 문제중심학습 수업 매뉴얼에 따라 실제 수업에 적용 하고 그 결과를 분석하였다. 연구 결과 문제중심학습 모형이 실업계 고등학생의 수업만족도에 긍정적인 영향을 끼쳤으며, 문제중심학습 모형에 따른 전문교과 수업을 통해 실업계 고등학생의 모든 영역의 직업기초능력(문제해결 및 발표 능력, 기술활용능력, 자원활용능력, 수리능력, 조직이해능력, 대인관계능력, 자기관리능력)이 향상되었음을 실증적으로 알 수 있었다. The purpose of this research was to analyze the fitness of problem-based learning(PBL) for improving the core competencies of vocational high school students. This study examined the core competencies of vocational high school students by using the advised BARS test for vocational high school. And in order to examine the effectiveness of the courses based on PBL, 4 teachers had taught the designed courses by PBL method during the regular class in vocational high school : agricultural; technical; commercial, home economic high schools. The major findings in this study were as follows: 1) The courses based on PBL had an positive effect on the class satisfaction of vocational High school students. 2) We found out that the courses based on PBL have a positive effect on improving vocational key competencies of Vocational High school students.

강연 : Mechanical Behavior of Connective Tissue

Keyoung Jin Chun 대한기계학회 1998 대한기계학회 춘추학술대회 강연집 Vol.- No.-

Tendon Responses Depending on Different Anatomical Locations

Keyoung Jin Chun,Robert P. Hubbard 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.7

The objectives of this work focus on the difTerences in responses of paired tendons from different anatomical locations. Tendon specimens were obtained from the hindlimbs of canines and frozen to -70℃. After being thawed, specimens were mounted in the immersion bath,<br/> preloaded to 0.13 N, and then subjected to 3% or 4% of the initial length at a strain rate of 5%hec. It was found that the mechanical responses of anatomically paired tendons were nearly the same within each pair but different between pairs of tendons from different anatomical locations. Although f1exor tendons had much larger cross-sectional area than the others, such as peroneus or extensor tendons, the stiffness of the flexor tendons were much lower than the others throughout their stress-strain responses. The nature and causes of these differences in the<br/> stiffness are not fully known. However, it is clear that differences in the mechanical response of tendons and other connective tissues are significant to the musculoskeletal performance.

Development of a reduced relaxation function and comparison of stress relaxation for anatomically paired tendons

Keyoung Jin Chun,Robert P. Hubbard 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.7

A new “standard nonlinear solid” reduced relaxation function has been developed to describe the measured relaxation responses of tendons with 3% and 4% strain levels. This new reduced relaxation function has been used in modeling tendon responses with the quasi-linear viscoelastic law. Unlike the reduced relaxation functions employed in previous studies, the present function closely fits the measured relaxation responses for both the short term of the first few seconds and the long term of 22 hours. The relaxation responses of the anatomically paired tendons were found to be more alike than those from different sites.

Development of a Functional Fixator System for Bone Deformity Near Joints

Keyoung Jin Chun,Ho Jung Lee 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.2

A functional external fixator system for bone deformity near the joints using worm gear was developed for curing the angle difference in fracture bones while the lengthening bar was developed for curing the differences in length, also in fracture bones. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for bone deformity near joints. The FE model using compressive and bending FE analysis was applied due to the angle differentiations. The results indicate that compressive stiffness value in the experiment was 175.43N/㎜, bending stiffness value in the experiment was 259.74N/㎜, compressive stiffness value in the FEA was 188.67N/㎜, and bending stiffness value in the FEA was 285.71N/㎜. Errors between experiments and FEA were less than 10% in both the compressive stiffness and the bending stiffness. The maximum stress (157㎫) applied to the angle to the angle of the clamp was lower than the yield stress (176.4㎫) of SUS316L. The degree of stiffness in both axial compression and bending of the new fixator are about 2 times greater than other products, with the exception of EBI (2003).

Constitutive Model of Tendon Responses to Multiple Cyclic Demands ( I ) - Experimental Analysis -

Keyoung Jin Chun,Robert P. Hubbard 대한기계학회 2001 KSME International Journal Vol.15 No.7

Constitutive Model of Tendon Responses to Multiple Cyclic Demands (II) - Theory and Comparison -

Keyoung Jin Chun,Robert P. Hubbard 대한기계학회 2001 KSME International Journal Vol.15 No.9

Sectional Differences in Tendon Response

Keyoung Jin Chun,Robert P. Hubbard 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.8

The objectives of this work here focus on the differences in responses to multiple cyclic tests of different sections along the length of the same tendon. Tendon specimens were obtained from the hindlimbs of canines and frozen to -70℃. After thawing. specimens were mounted in the immersion bath at room temperature (22℃), preloaded to 0.13 N and then subjected to 3% or 4% of the initial length at a strain rate of 5%/sec. It was found that different sections of the same long tendons had different resistances to deformation. In general. the bone end sections were stiffer and carried greater loads for a given strain than the muscle end sections, and the mid-portions were the least stiff and carried the smallest loads for a given strain. The results of this study offer new information about the mechanical responses of collagenous tissues. We know more about their responses to multiple cyclic extensions and how their responses are different from the positions along the length of the tendon specimen. The nature and causes of these differences in the stiffness are not fully known. However, it is clear that differences in the mechanical response of tendons and other connective tissues are significant to musculoskeletal performance.