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해석요소 선택에 따른 주철제 맨홀 및 틀의 구조해석기법
이형욱(H. W. Lee),박근영(G. Y. Park),김덕원(D. W. Kim),김명호(M. H. Kim),김승중(S. J. Kim) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.10
Manholes are constructed on road in order to maintain water and sewage pipelines as an entering gate for related persons. Recently locking devices of a manhole have been developed to prevent lost or stolen of the manhole. In this study, stress analysis of a cast-iron manhole was carried out as a part of the lightweight design. Stress analysis according to the solid elements selection was conducted to search a proper the tetra element for applying to complicated geometry model. Maximum stress, the deflection at the center, and stress distribution were considered as main factors in the comparison. The result of the normal second-order tetra element(C3D10) was similar to that of the first-order hex element with incompatible mode(C3D8I) in this case.
권민경,최재림,최준열,장경환,김성권,김덕원,Kwon, M.K.,Choi, J.L.,Choi, J.Y.,Jang, K.H.,Kim, S.K.,Kim, D.W. 대한의용생체공학회 2012 의공학회지 Vol.33 No.2
With rapid increasing usage of smart phones, social concerns have arisen about the possible effects of electromagnetic fields emitted from wideband code division multiple access(WCDMA) mobile phones on human health. The number of people with self-reported electromagnetic hypersensitivity(EHS) who complain of various subjective symptoms such as headache, insomnia etc. has also recently increased. However, it is unclear whether EHS results from physiological or other origins. In this double-blinded study, we investigated physiological changes such as heart rate, respiration rate, and heart rate variability with real and sham exposures for 15 EHS and 17 non-EHS persons using a module inside a dummy phone. Experiment was conducted using a WCDMA module with average power of 24 dBm at 1950 MHz with the specific absorption rate of 1.57 W/kg using a headphone for 32 min. As a conclusion, WCDMA RF exposure did not have any effects on the physiological variables in either group.
김수찬,강승일,김승철,황정호,김성녕,김영,송선대,조상래,김덕원,Kim, S. C.,Kang, S. I.,Kim, S. C.,Hwang, J. H.,Kim, S. Y.,Kim, Y.,Song, S. D.,Cho, S. N.,Kim, D. W. 대한의용생체공학회 2002 의공학회지 Vol.23 No.3
결핵을 진단하는 방법 중에서 신속하고 비교적 비용이 적게드는 방법은 객담을 통한 결핵균 도말 검사이다. 결핵균 도말 검사는 슬라이드에 도말한 환자의 객담을 가온 과정을 통해 고착시키고. acid-fast 염색방법을 통해 염색시킨 후 현미경으로 결핵균을 관찰하는 것이다. Acid-fast 염색방법은 크게 hot staining과 cold staining 방법 두 가지가 있으며, 우리나라에서는 염색 결과가 선명한 hot staining 방법인 Ziehl-Neelsen 방법을 주로 이용한다. 그러나, 기존의 결핵균 자동염색기는 가온 기능이 없어 환자의 객담을 슬라이드에 검사자가 고착을 시켜야 하고. 선명도도 낮은 문제점을 가지고 있다. 본 연구에서는 검사자의 인력 절감과 검사자 개인의 염색 능력에 따른 염색 정도의 변화를 줄이기 위해 가온이 가능한 결핵균 자동염색기를 개발하였다 개발된 염색기는 객담의 고착에서 염색 그리고 건조가지 전 과정이 자동으로 이루어진다. 염색 시간은 5개의 슬라이드를 고품질로 염색할 경우 21분이 소요되었다. 성능 평가를 위해 총 91개 객담을 대상으로 자동과 수동염색을 시행하여 일치율을 비교해 본 결과 75%로 통계적으로 유의한 차이를 보이지 않았다 (P>0.05). The detection of tubercle bacilli (TB) from sputum smear is one of the fast and inexpensive methods for diagnosis of tuberculosis. For this method. sputum smears are usually flexed by heating and stained by acid-fast staining method, and then examined under an optical microscope. Two Procedures are commonly used fur TB staining. One is hot staining and the other is cold staining method. The Ziehl-Neelsen method which is a hot staining method is widely used in Korea because its stained color is more vivid However, the conventional automated stainer has to fix the sputum smear on a slide manually and the stain is not so vivid because it has not heating function. In an effort to save labor and minimize variations in manual staining Procedure. we developed an automated stainer with heating function. The entire staining process is fully automated. from fixation to final washing and drying. With the automated methods, five slides can be flexed and stained in 21 minutes at consistent high quality We compared the concordance rate between the two methods for 91 sputum samples to validate the stain quality of the developed automated stainer. As the results, the concordant rate between the two methods was 95% and there was no significant difference (p>0.05)
랜덤 포리스트를 이용한 비제어 급성 출혈성 쇼크의 흰쥐에서의 생존 예측
최준열,김성권,구정모,김덕원,Choi, J.Y.,Kim, S.K.,Koo, J.M.,Kim, D.W. 대한의용생체공학회 2012 의공학회지 Vol.33 No.3
Hemorrhagic shock is a primary cause of deaths resulting from injury in the world. Although many studies have tried to diagnose accurately hemorrhagic shock in the early stage, such attempts were not successful due to compensatory mechanisms of humans. The objective of this study was to construct a survival prediction model of rats in acute hemorrhagic shock using a random forest (RF) model. Heart rate (HR), mean arterial pressure (MAP), respiration rate (RR), lactate concentration (LC), and peripheral perfusion (PP) measured in rats were used as input variables for the RF model and its performance was compared with that of a logistic regression (LR) model. Before constructing the models, we performed 5-fold cross validation for RF variable selection, and forward stepwise variable selection for the LR model to examine which variables were important for the models. For the LR model, sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (ROC-AUC) were 0.83, 0.95, 0.88, and 0.96, respectively. For the RF models, sensitivity, specificity, accuracy, and AUC were 0.97, 0.95, 0.96, and 0.99, respectively. In conclusion, the RF model was superior to the LR model for survival prediction in the rat model.
이어폰 및 헤드폰의 정자기장이 인공심장 박동기 및 이식형 제세동기에 미치는 영향
정재원,최수범,박지수,김덕원,Chung, J.W.,Choi, S.B.,Park, J.S.,Kim, D.W. 대한의용생체공학회 2015 의공학회지 Vol.36 No.1
In this study, we evaluated the effects of static magnetic fields of earphones and headphones on pacemakers and implantable cardioverter defibrillators(ICDs). Five pacemakers and three ICDs were subjected to in-vitro test with three headphones which were an in-ear earphone, clip-on headphone, and closed-back headphone. Each implantable device was placed in close proximity(within 3 mm) to the ear-pad of each of the earphone and headphones for 3 min. As a result, no effects were observed on the pacemakers for the earphone and headphones during the test, but an effect was observed on one ICD for the clip-on and closed-back headphone during the test. When the ICD was placed in close proximity to the headphones, the ICD temporarily suspended functions of tachyarrhythmia detection and therapy. The effect was not observed in this study when the headphones were at least 2 cm from the ICD. Based on these findings, patients with ICDs should be advised to keep earphones and headphones at least 2 cm apart from their ICDs.
지원벡터기계를 이용한 출혈을 일으킨 흰쥐에서의 생존 예측
장경환,최재림,유태근,권민경,김덕원,Jang, K.H.,Choi, J.L.,Yoo, T.K.,Kwon, M.K.,Kim, D.W. 대한의용생체공학회 2012 의공학회지 Vol.33 No.1
Hemorrhagic shock is a common cause of death in emergency rooms. Early diagnosis of hemorrhagic shock makes it possible for physicians to treat patients successfully. Therefore, the purpose of this study was to select an optimal survival prediction model using physiological parameters for the two analyzed periods: two and five minutes before and after the bleeding end. We obtained heart rates, mean arterial pressures, respiration rates and temperatures from 45 rats. These physiological parameters were used for the training and testing data sets of survival prediction models using an artificial neural network (ANN) and support vector machine (SVM). We applied a 5-fold cross validation method to avoid over-fitting and to select the optimal survival prediction model. In conclusion, SVM model showed slightly better accuracy than ANN model for survival prediction during the entire analysis period.