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구조 동특성 파라미터를 이용한 구조물 손상 탐색기법 비교 연구
최병민(Choi, Byoung-Min),우호길(Woo, Ho-Kil) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.3
Detection of structural damage is an inverse problem in structural engineering. There are three main questions in the damage detection: existence, location and extent of the damage. In concept, the natural frequency and mode shapes of any structure must satisfy an eigenvalue problem. But, if a potential damage exists in a structure, an error resulting from the substitution of the refined analytical finite element model and measured modal data into the structural eigenvalue equation will occur, which is called the residual modal forces, and can be used as an indicator of potential damage in a structure. In this study, a useful damage detection method is proposed and compared with other two methods. Two degree-of-freedom system and Cantilever beam are used to demonstrate the approach. And the results of three introduced method are compared.
수술용 장갑 사용자들의 고무 ( Latex ) 알레르기 유발에 관한 연구
최병민(Byoung Min Choi),김영국(Young Guk Kim),정지태(Ji Tae Choung),독고 영창(Young Chang Tockgo) 대한소아알레르기호흡기학회(구 대한소아알레르기 및 호흡기학회) 1994 소아알레르기 및 호흡기학회지 Vol.4 No.1
N/A Latex surgical gloves may cause contact urticaria and serious allergic reactions in sensitized persons. The purpose of this study was to assess the symptom prevalence of latex sensitivity in a large group of hospital personnel in Korea. In the present study, 206 hospital personnel(Doctors and Nurses) in Korea University Medical Center, Anam & Guro Hosp., answered the questionnaire about symptoms associated with latex glove wearing. The results were as follows; 1) Sixty six(32%) of the 206 answered the questionnaire reported at least one symptom when wearing gloves. Twenty three(34.8%) of the 66 personnel who had one symptom had itching and redness. Nineteen(28.8%) of the 66 had itching without redness or wheal when wearing gloves. Seventeen(25.8) had itching, redness and wheal(Table 1), 2) Except 19 who had itching without redness or wheal, the symptom prevalence of latex sensitivity to latex gloves was 22.8%. 3) Symptom prevalence was not significantly different in men and women. 4) Among the hospital personnel who had allergic disease, the symptom prevalence of latex sensitivity to latex gloves was significantly higher(45.3%) than in personnel without allergic disease. 5) The frequency of exposure to latex gloves did not influence the symptom prevalence. 6) Seven(14.9%) of the symptomatic personnel had sought medical advice, and 17 chose to wear cotton gloves or plastic gloves under the latex gloves. 7) All symptoms were local and no personnel reported systemic urticaria or anaphylaxis during surgery. As the above results, the symptom prevalence of latex sensitivity was 22.8%. To prevent further serious reactions to latex rubber, hospital personnel and patients with histories suggestive of rubber allergy should be evaluated about latex sensitivity before procedures involving substantial contact with latex. Laboratory investigations to identify such patients and necessary measures to prevent rubber contact during surgery in sensitized patients are presented.
친환경 자재가 배 과원의 병해충 방제 효과 및 과실 품질 특성에 미치는 영향
최현석 ( Choi Hyun-sug ),오수옥 ( Wu Xiu-yu ),김월수 ( Kim Wol-soo ),이연 ( Lee Youn ),최병민 ( Choi Byoung-min ),국용인 ( Kuk Yong-in ) 한국유기농업학회 2011 韓國有機農業學會誌 Vol.19 No.3
Organic materials, such as chitin incubated solution (CIS) combined with neem oil (NO), nano silver silica (NSS), and Bordeaux mixture (BDM), were applied with and without agricultural chemicals (AC) (insecticide and fungicide) to investigate scab and mealybug occurrences and fruit qualities on ‘Niitaka’ pear trees in orchards in 2006. Fruits and leaves grown under CIS+NO without AC had less than 30%, scab occurrence, but CIS+NSS or CIS+BDM without AC had higher scab occurrence. Organic materials with AC decreased the scab to less than 20%. All treatments decreased mealybug occurrences to less than 10%, except for the fruits grown under CIS+BDM without AC. Fruit qualities varied among the treatments. Hunter value a, representing for the redness degree, was higher for fruits treated with CIS+NSS and CIS+BDM without AC than those with AC. Fruits treated with organic materials without AC had greater total phenolic and flavonoid compounds as well as antioxidant capacity in flesh and greater total phenolc compounds and antioxidant capacity in peel than those treated with the AC.
고한성,최정훈,최병민,유기환,홍영숙,이주원,김순겸,Ko Han Seong,Choi Jeong Hoon,Choi Byoung Min,Yoo Kee Hwan,Hong Young Sook,Lee Joo Won,Kim Soon Kyum 대한소아신장학회 2000 Childhood kidney diseases Vol.4 No.1
목 적 : 소변내 Ca 배설량을 측정하는데 있어 24시간 뇨 Ca 배설량 측정이 흔히 사용되어 왔으나, 이의 결과를 알기까지 많은 시간과 비용이 소모되는 단점이 있어 빠른 시간내에 결과를 알 수 있는 간편한 검사를 알아보기 위해 저자들은 소변내 Ca 배설량이 소변내 sodium(Na), potassium(K), creatinine(Cr)과 밀접한 관련이 있음에 착안하여 일회뇨(Spot urine) Na/K 비를 이용하여 요칼슘배설량을 예측할 수 있는지 알아보기 위하여 이 연구를 시행하였다. 대상 및 방법 : 1998년 5월부터 7월까지 고려대학교 의료원 구로병원 소아과에 비뇨기계 증상으로 입원한 환아 84명을 대상으로 spot urine에서 Na, K, Ca, Cr를 측정하여 Ca/cr비와 Na/K 비를 서로 비교하였다. 또한 고칼슘뇨증 (Ca/cr비 >0.21)으로 예측할 수 있는 Na/K 비의 cut off value를 계산하여 그 민감도, 특이도, 양성예측도, 음성예측도를 구하였다. 결 과 : 1) spot urine Ca/cr비와 Na/K비와는 통계적으로 의의있는 상관관계를 보였다(r=0.496,P<0.001, Ca/cr=Na/K x 0.01671-0.061). 2) 고칼슘뇨증으로 예측할 수 있는 spot urine Na/K비의 cut off value를 2.68로 정했을 경우 민감도 $100\%$, 특이도 $54.5\%$, 양성예측도 $37.5\%$, 음성예측도 $100\%$를 보였다. 결 론 : 소변내 Ca 배설량을 예측하는데 spot urine Na/K 비를 이용할 수 있으리라 생각되며,이는 고칼슘뇨증의 선별에도 유용하리라 생각된다. Purpose. Urinary calcium excretion using a 24-hr urine colledtion has been used for the diagnosis of hypercalciuria up to now. But It takes a lot of time and costs much. We have investigated on a more simple method for screening of hypercalciuria in children. Methods: We had retrospectively analyzed sodium, potassium, calcium and creatinine in spot urine of eighty-four patients with urinary symptoms from May 1998 to July 1998 in Korea university Guro hospital and compared the urinary Ca/Cr ratio with the Nin ratio. Using a urinary Nan ratio >2.68 as a cutoff value in predicting the occurrence of hypercalciuria, we measured its sensitivity, specificity, positive predictive value and the negative predictive value. Results: A direct relationship was found between urinary Na/K and Ca/Cr ratio (r=0.496, P<0.001, Ca/Cr : Na/K x 0.0167+0.061). Using a urinary Na/K ratio >2.68 as a cutoff value in predicting the occurrence of hypercalciuria, its sensitivity was found to be $100\%$ and its specificity $54.5\%$. The positive predictive value was $37.5\%$ and the negative predictive value $100\%$. Conclusions : Spot urine Na/K ratio is a valuable test for the screening of hypercalciuria in children.
유전자 알고리즘을 이용한 구조물 손상 탐색기법에 관한 연구
우호길(Woo, Ho-Kil),최병민(Choi, Byoung-Min) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.1
In this paper, a method for identifying the location and extent of a damage in a structure using residual forces was presented. Element stiffness matrix reduction parameters in a finite element model were used to describe the damaged structure mathematically. The element stiffness matrix reduction parameters were determined by minimizing a global error derived from dynamic residual vectors, which were obtained by introducing a simulated experimental data into the eigenvalue problem. Genetic algorithm was used to get the solution set of element stiffness reduction parameters. The proposed scheme was verified using Euler-Bernoulli beam. The results were presented in the form of tables and charts.