강구 경사충돌에 의한 유리의 손상 거동에 대한 실험적 연구 및 유한요소 해석

서창민,김성호,김동균,Seo, Chang-Min,Kim, Seong-Ho,Kim, Dong-Gyun 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.5

The damage behavior of soda-lime glass was studied due to a steel ball of 1mm and 2mm at oblique impact test. The thickness of glass specimen were 3mm and 5mm and oblique degrees of impact were 90$^{\circ}$,70$^{\circ}$ and 50$^{\circ}$. After the steel ball impact test, the crack patterns were investigated using a stereo-microscope. In addition, the finite element method was performed to analyze the stresses distribution and variation in the oblique impacted glass by steel ball. As a result of the impact test, the crack length of 90$^{\circ}$impacted glass was the largest and that of 50$^{\circ}$impacted glass was the smallest. In particular, as the impact velocity and diameter of the steel ball increased, the difference of crack length was prominent. The finite element analysis showed the maximum principle stresses distribution in contact area of glass specimen. The result of analysis was accorded with the crack growth behavior by the oblique impact test.

세라믹 코팅된 1Cr-1Mo-0.25V강의 피로균열성장 특성

서창민,김경렬,Seo, Chang-Min,Kim, Gyeong-Ryeol 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.10

Fatigue tests were performed to investigate the effect of ceramic coatings as in TiN and TiCN on fatigue crack growth properties of ceramic coated 1Cr-1Mo-0.25V steel with different coating thickness in laboratory air conditions. The experimental results are described with respect to a Paris equation, da/dN=C(.DELTA.K)$^{m}$ , where the crack growth rate of coated specimens provided as similar growth rate as that of the uncoated specimen regardless of coating thickness. Furthermore, it was observed that the type of coating layer had virtually no effect on crack growth rate in the full region of stress intensity factor range. And it was also appeared that the final crack length of TiCN coated specimens was short compared to that of TiN coated, and the substrate specimens, in which it was inferred due to lowering the toughness of coated material from high hardness of TiCN coating layer itself.

입자충격에 의한 유리의 손상기구에 관한 실험적 연구

서창민,신형섭,황병원,Seo, Chang-Min,Sin, Hyeong-Seop,Hwang, Byeong-Won 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.6

A quantitative study of impact damage of a soda-lime glass was carried out. An initiation and a propagation of cracks by the impact of two inds of steel ball was investigated. The fron, side and rear view of cracks were observed by a stereo-microscope. And the lowering of the benidng strength due to the impact of steel balls was examined through the 4-point bending test. A transparent glass is very helpful to understand and analyze the impact damage behavior of another brittle matereial. A deagdram about crack patterns according to the threshold impact velocity was sketched. A ring crack and a cone crack were formed at the low impact velocity. And as the impact velocity was higher, initial lateral crack was generated on the slanting surface of cone crack, and radial cracks were generated from the outermost ring crack. When the impact velocity of steel balls exceed a critical velocity, the contact site of specimens were crushed. According to the propagation of a cone crack, a rapid strength degradation occurred. In the specimen having crushed region, a bending strength was converged to a constant value instead of strength degradation.

칼라 좌표계와 주성분 분석법을 이용한 외부환경에 적응적인 손 모양 추적 및 인식

서창민(Chang-Min Seo),이응주(Eung-Joo Lee) 제어로봇시스템학회 2006 제어로봇시스템학회 합동학술대회 논문집 Vol.2006 No.12

통증 치료실 내원 환자의 분석

서창민(Chang Min Seo),문철원(Cheol Won Mun),백운이(Un Yi Baek),흥정길(Jung Gil Hong) 대한통증학회 2000 The Korean Journal of Pain Vol.13 No.2

N/A Background: Currently, the number of patients visiting pain clinics is increasing with the augmented concems of the patients about management of pain. We conducted this study in order to comprehend the characteristics of the patients visiting pain clinics and to find a method to further raises the public's awareness about pain treatment. Methods: We surveyed 497 new patients who had visited pain clinic of Kyungpook national university hospital from August 1998 to July 1999. We analysed these patients about their age, sex, chief complaint, duration of pain complaints, resident district, educational level and route of visiting pain clinic by use of questionnaire. Results: In age distribution, the largest proportion (29.8%) were in their 60's. Low back pain was the most comman chief complaint (33.0%), the highest (43.7%) percentage of patients had complained of pain for over 6 months. Two thirds of the patients lived in urban area. Patients who were educated to only elementary school level made up the largest group with 35.3%. Referrals from former patients who had visited our pain clinic and had received treatment. Conclusions: As increasing patients who have pain complaints are related to social advanced age, it is prudent to consider the characteristics of age related pain complaints. And we have to guide the pain patients to have more earlier treatments using mass media because there is still insufficient general information about pain clinic and pain managements.

얼굴 특징자 기반의 얼굴인식 및 해석시스템

서창민(Chang-Min Seo),김민성(Min-Sung Kim),강동중(Dong-Jung),김성진(Sung-Jin Kim),이응주(Eung-Joo Lee) 한국멀티미디어학회 2005 한국멀티미디어학회 학술발표논문집 Vol.2005 No.1

Morphological Study of the Subdeltoid Bursa and its Innerrvation

서창민 ( Chang Min Seo ),전안나 ( Anna Jeon ),정윤희 ( Yoon Hee Jeong ),김경용 ( Kyung Yong Kim ),한승호 ( Seung Ho Han ),이원복 ( Won Bok Lee ) 중앙대학교 의학연구소 2017 中央醫大誌 Vol.42 No.1

The subdeltoid bursa is one of the main structures that cause shoulder pain. Previous studies have discussed the locations and innervation of sensory nerve of the subacromial bursa at large, and there was no detailed study focusing on the subdeltoid bursa. The aim of this study was to accurately identify the distribution of sensory nerve branches running to subdeltoid bursa with mesoscopic dissection and the boundaries after injecting gelatin into the bursa. Fifteen shoulders of 11 Korean soft cadavers were dissected (average age 65, age ranged 43~88 years). The most prominent point of greater tubercle of the humerus (GT) were used reference point. The horizontal line passing through GT was used as x-axis and the vertical line passing through the GT was used as y-axis. The average anterior, posterior, superior, and inferior were 1.9±0.6, 2.4±1.3, 2.1±0.7, and 3.2±1.5 cm from the GT, respectively. The most common shape of subdeltoid bursa was oval shape. In 15 shoulders, the anterior branch of the axillary nerve distributed to subdeltoid bursa with running posteriorly. The muscular branch of anterior and middle parts of the deltoid distributed to the branch of nerve that into the subdeltoid bursa. Most branches of axillary nerve were distributed in the posterolateral area. Chung-Ang J Med 2017; 42(1): 25-30

스마트폰 중독 정도와 한국형 청소년 자기행동평가척도와의 상관성에 대한 연구

서창민(Chang Min Seo),이종훈(Jonghun Lee),최태영(Tae Young Choi),김지현(Jihyun H. Kim),신임희(Imhee Shin),우정민(Jungmin Woo) 대한생물치료정신의학회 2012 생물치료정신의학 Vol.18 No.2

Objectives:Recent years, the smart-phone usage has been rapidly increased. While it gave us many conveniences and be-nefits, the adverse effects also came to emerge and threatened individual’s mental health. Especially, its overusage in the adolescents can have substantial impact on their psychosocial development. We aim to evaluate the psychopathologies of the adolescents according to smart-phone addiction level, by using the Korea-Youth Self Report. Methods:We selected four high schools within Daegu, Korea. Among the smart-phone users, 276 subjects were enrolled. The severity of addiction was measured through ‘2010 Smart-phone Addiction Rating Scales’ guided by the Korean Internet & Security Agency. The psychopathologies of the subjects were evaluated with the Korea-Youth Self Report. Results:The total score of the Smart-phone Addiction Rating Scales and the total problematic behavior score of Korea- Youth Self Report showed a positive correlation(r=.412, p<0.001). The group with more severely addicted showed higher T-scores on the nine of eleven subscales of the Korea-Youth Self Report[somatic complaints(p<0.05), anxiety/ depression(p<0.01), thought problems(p<0.01), attention problems(p<0.001), delinquency(p<0.001), aggressiveness(p <0.001), inter- nalizing problems(p<0.001), externalizing problems(p<0.001), total problematic behaviors(p<0.001)]. Among the contents and situations of smart-phone usage, utilizing the smart-phone for Social Network Services(OR : 1.83 ; 95% CI :1.29-2.59) and situations of smart-phone usage like ‘in bedtime’(OR : 1.52, 95% CI :1.04-2.23), ‘at bathroom’(OR : 1.84, 95% CI :1.28-2.65) w-ere risk factors for high level group of smart-phone addiction. Conclusions:We suggest that smart-phone addiction level is related to compromised psychological well-being of the adolescences. Also, Specific purpose and situations of smart-phone usages are associated to smart-phone addiction level. In the future, if more obvious psychopathologies and risk factors are grasped, it may be helpful in screening and intervention of high risk adolescent to smart-phone addiction.

취성재료의 손상후 잔류강도 평가

신형섭,오상엽,서창민,Sin, Hyeong-Seop,O, Sang-Yeop,Seo, Chang-Min 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.5

In structural applications, brittle materials such as soda-lime glasses and ceramics are usually subjected to multiaxial stress state. Brittle materials with cracks or damage by foreign object impacts are apt to fracture abruptly from cracks, because of their properities of very high strength and low fracture toughness. But in most cases, the residual strength of structural members with damage has been tested under uniaxial stress condition such as the 4-point bend test. Depending upon the crack pattern developed, the strength under multiaxial stress state might be different from the one under uniaxial. A comparative study was carried out to investigate the influence of stress state on the residual strength evaluation. In comparable tests, the residual strength under biaxial stress state by the ball-on-ring test was greater than that under the uniaxial one by the 4-point bend test, when a small size indendation crack was introduced. In the case that crack having an angle of 90deg. to the applied stress direction, the ratio of biaxial to uniaxial flexure strength was about 1.12. The residual strength was different from crack angles to loading direction when it was evaluated by the 4-point bend test. The ratio of residual strength of 45deg. crack to 90deg. one was about 1.20. In the case of specimen cracked by a spherical impact, it was shown that an overall decrease in flexure strength with increasing impact velocity, and the critical impact velocity for formation of a radial and/or cone crack was about 30m/s. In those cases that relatively large cracks were developed as compared with the case of indented cracks, the ratio of residual strength under biaxial stress state to one uniaxial became small.

용접부의 고온 재료물성에 대한 실험적 연구

백운봉,윤기봉,서창민,이해무,Baek, Un-Bong,Yun, Gi-Bong,Seo, Chang-Min,Lee, Hae-Mu 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.12

High temperature material properties of a welded joint were experimentally studied. Tensile and creep properties were measured for each part of weld metal. HAZ(heat affected zone) and parent metal at 538$^{\circ}C$. HAZ metal was obtained by a simulated heat treatment. Results showed that the order of tensile strength is weld>HAZ> parent both at 24$^{\circ}C$ and at 538$^{\circ}C$. Creep resistance was also the highest for weld metal and lowest for parent metal. Creep rupture life curves were obtained and converted to Monkman-Grant relation which is useful for life assessment. Use of the data obtained in this study is discussed.