대공간 지붕 파라메트릭 모델링 기법 및 구조해석모델 구축을 통한 최적대안 설계방법

김치경,김시욱,Kim, Chi-Gyeong,Kim, Si-Uk 한국전산구조공학회 2018 전산구조공학 Vol.31 No.2

Non-linear analysis of skew thin plate by finite difference method

김치경,황명환 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4

This paper deals with a discrete analysis capability for predicting the geometrically nonlinear behavior of skew thin plate subjected to uniform pressure. The differential equations are discretized by means of the finite difference method which are used to determine the deflections and the in-plane stress functions of plates and reduced to several sets of linear algebraic simultaneous equations. For the geometrically non-linear, large deflection behavior of the plate, the non-linear plate theory is used for the analysis. An iterative scheme is employed to solve these quasi-linear algebraic equations. Several problems are solved which illustrate the potential of the method for predicting the finite deflection and stress. For increasing lateral pressures, the maximum principal tensile stress occurs at the center of the plate and migrates toward the corners as the load increases. It was deemed important to describe the locations of the maximum principal tensile stress as it occurs. The load-deflection relations and the maximum bending and membrane stresses for each case are presented and discussed.

중저층건물 구조설계 통합시스템

김치경,Kim, Chi-Gyeong 한국건축구조기술사회 2006 건축구조 Vol.13 No.3

고온 및 저온처리와 자외선조사에 의한 campylobacterjejuni의 살균효과

김치경,임선희,윤만석,오학식,조민기 한국미생물학회 1989 미생물학회지 Vol.27 No.3

Campylobacter jejuni was studied for its disinfection by heat-and cold-treatment and UV-irradiation. When C. jejuni was treated by heat, no viable cell was found after 10 min treatment at $55^{\circ}C$, whereas small fraction of cell population was survived after 60 min treatment at $45^{\circ}C$ and $50^{\circ}C$. When they were treated by cold temperature for 30 days, no cell was survived at -$23^{\circ}C$ but about 4 log of the cells were survived at both temperature of $4^{\circ}C$ and -$40^{\circ}C$. When the organisms were UV-irradiated, thier survival rates were proportionally varied to the distance of irradiation. The scanning electron microscopic studies of C. jejuni cells treated by the disinfecting agents revealed that shapes of thecells were deformed from spiral rod into spherical form. The heat-treated cells showed rough and damaged surface on the scanning electron micrographs. In the heat-treated cells, some proteins of high molecular weight appeared to become accumulated in the electrophoretic analysis. The DNAs extracted from the cells treated with the physical agents showed some differences in agarose gel electrophoresis, comparing those of normal cells.

An analytical solution to heat conduction with a moving heat source

김치경 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.4

This paper deals with an analytical solution to heat conduction in the medium subjected to a moving heat source. It evaluates the temperature distribution around a rectangular shape source moving at a constant speed along the axis of a bar. The transient temperature field from a moving heat source was analyzed using a Fourier series procedure. The most interesting result of the theory, is the derivation of a single formula capable of predicting the cooling time and cooling rate with a fairly good accuracy for ranges of temperature. Because of the passage of the heat source, the rise of temperature produced at a given near the source, tends to rapidly become constant. Several sample problems are discussed and illustrated, and comparisons with numerical approaches where these can also be used made. The results show that these solutions are in good agreement with the numerical results.

탄성지반 구조물에 유한요소와 경제요소의 절충법 적용

김치경 한국리스크관리학회 2007 리스크 管理硏究 Vol.18 No.1

본 연구는 지반과 구조물의 상호작용 문제의 해석을 유한요소-경계요소 절충법으로 수행하였다. 유한요소-경계요소 절충법은 일반적으로 구간별 연속방정식의 단계에서 행하여진다. 오직 표면분할 만 요구되는 경계요소법을 사용하여 시스템의 등가강성행렬을 유도하고 이 등가강성행렬은 유한요소법에서와 같은 방법으로 수행되어 전체유한요소 정식화로 절충화 된다. 경계요소법의 비대칭 요소행렬이 실질적 정확도의 손실 없이 절충화 속에서 대칭 화 된다. 이차원 탄성문제를 선택하여 유한요소-경계요소 절충법을 적용시켜 타당성을 입증하고 유한요소법의 결과치와 비교 검토하였다.

A Study on the Stability of Circular Thin Plates by Nonlinear Analysis

김치경 대한안전경영과학회 2011 대한안전경영과학회지 Vol.13 No.2

본 연구에서는 원형 박판 구조물의 안정성에 대하여 해석 하였다. 임계하중은 하중을 점차적으로 증가하여 구조물이 파괴가 발생하여 안정성을 상실 하는 상태에서 가장 작은 하중을 의미한다. 판구조의 안정성을 임계하중의 크기로 기초를 두고 해석 하였다. 원형 박판구조의 차분해석은 일반 판구조와 같으므로 최근에 많은 연구의 대상이되어왔다. 차분법은 복잡한 구조물에서도 물론, 다양한 경계조건을 포함하는 문제에 이르기까지 효과적인 수치방법이다. 본 연구에서는 기본 박판구조의 지배방정식을 유도하고 차분화 하여 직접적으로 접근하였다. 원 둘레 의 지점이 힌지 받침으로, 등분포 하중을 받고 있는 박판을 기하학적 비선형 해석으로 수행하여 원형 박판의 처짐 및 응력을 해석 하였다.

Spontaneous Carotid Cavernous Fistula in a Case with Protein S Deficiency that Newly Developed Ophthalmoplegia after Embolization

김치경,신제영,장준영,이승훈 대한신경과학회 2011 Journal of Clinical Neurology Vol.7 No.3

Background Carotid cavernous fistula (CCF) is an abnormal communication between the carotid artery and the cavernous sinus. The pathogenesis of spontaneous CCF remains unclear,although sinus thrombosis is known to be a predisposing factor for dural arteriovenous fistula. Because spontaneous CCFs are mainly of the dural type, we considered that thrombogenic conditions, such as, protein S deficiency might be associated with CCF. Case Report A 42-year-old woman complained of conjunctival injection and retro-orbital pain that first appeared 1-month before visiting our hospital. She had no history of head trauma or intracranial surgery. Exophthalmos and chemosis were observed in her left eye, which also had lower visual acuity and higher intraocular pressure than the right eye. Magnetic resonance images and cerebral angiography revealed a left dural CCF. Her protein S was low, at 41%(normal range: 70-140%), but other hematologic values related to coagulation were normal. Her symptoms were relieved after initial transvenous coil embolization. However, a newly developed sixth-nerve palsy was detected 4 days after initial embolization. Follow-up angiography revealed a minimal shunt, and thus transvenous coil embolization was repeated. Two days later, the ophthalmoplegia started reducing, and 1-month later it had almost disappeared. Conclusions To the best of our knowledge, this is the first report of spontaneous dural CCF in a Korean patient with concurrent protein S deficiency. Interestingly, transient sixth-nerve palsy developed after transvenous coil embolization in this patient. This additional symptom caused by the residual fistula was relieved after additional transarterial embolization.

하천수에서 Campylobacter jejuni 의 오염도와 그 생존율에 관한 연구

김치경,오학식,염곤,조민기 ( Chi Kyung Kim,Hak Shik Oh,Kon Ryeom,Min Ki Cho ) 한국하천호수학회 1986 생태와 환경 Vol.19 No.3·4

Campylobacter jejuni isolated from river and lake waters and chicken samples were examined for their contamination and survival in surface waters and for inactivation by chlorination. The isolation rates of C. jejuni from chicken samples were 50 to 100%, while only one out of 48 studies was positive from the surface water. When the organisms suspended in sterile river water were incubated at 4℃, they survived upto 20 days, but they died off after 1 day incubation at 30℃ or above. The in situ survival studies of C. jejuni in the waters of Dsecheong Dam and Han-river (1st bridge) revealed that they survived upto 14 days in winter, but for shorter period of time in spring and summer. The survival rates of the organism in the deeper water were a little longer than in the surface water, but the rates were not different between the both water environments. When the organisms were treated with 0. 5, 1. 0 and 2. 0 ㎎/ℓ chlorine solution at pH 7. 0 and 15℃ for 60 minutes, they were inactivated by about 1, 4, and 6 logs, respectively, The inactivation rate was increasingly affected by lowering the reaction pH and by increasing the reaction temperature.

Relationship Between Cerebral Microbleeds and Aspirin Use Regarding White Matter Hyperintensity Volume

김치경,한정훈,정한영,오경미,박진호,권형민 대한신경초음파학회 2021 대한신경초음파학회지 (JNN) Vol.13 No.1

Background: The association between antiplatelet use and cerebral microbleeds (CMBs) remains controversial. Herein, we investigated the effects of aspirin use on CMBs according to white matter hyperintensity (WMH) volume. Methods: CMBs were detected on gradient-recalled echo magnetic resonance imaging, and the volume of WMH was measured quantitatively. Information about aspirin use was obtained using a structured questionnaire, and other clinical and laboratory variables were investigated. The association between aspirin use and the presence of CMBs was evaluated according to WMH volume quartiles. Results: Among 1,642 neurologically asymptomatic subjects, 69 (4.2%) had CMBs and 126 (8%) had taken aspirin. The mean volume of WMH was 2.7 mL, and the average age was 56 years. The proportion of aspirin use did not differ between the two groups with or without CMBs (13% vs. 7%, respectively, p=0.11). In the highest quartile for WMH volume, the prevalence of CMBs and aspirin use increased compared with the lowest quartiles (10% vs. 1% for CMBs, and 11% vs. 4% for aspirin use). However, in each quartile of WMH volume, the proportion of aspirin use did not differ between subjects with and without CMBs. Chronological age and hypertension were associated with the presence of CMBs in both univariate and multivariate analyses after adjusting for WMH volume, but aspirin use did not increase the prevalence of CMBs in logistic regression analysis. Conclusion: Using WMH volume as a radiological marker for the vulnerable brain could not assist in distinguishing high-risk subjects for an increased prevalence of CMBs with regard to aspirin use.