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MFC 센서를 이용한 응력 확대 계수 측정에 관한 연구
오동진,김명현,Oh, Dong-Jin,Kim, Myung-Hyun 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.3
Recently, the structural failures due to fatigue occur frequently with the increase of size of ships and offshore structures. In this respect, the assessment of fatigue life and the residual strength are very important. Currently, the smart materials technology has demonstrated a variety of possibilities for a diagnosis of structural strength and structural health condition for large structures. The benefits and feature of the MFC sensor are more flexible, durable and reliable than conventional smart material. In this study, Micro Fiber Composite (MFC) sensor for the measurement of stress intensity factor (SIF) of two dimensional cracks induced in a structure is developed. Two MFC sensors are placed in the vicinity of the crack tip close to each other with the crack tip in between them. The SIFs of Mode I($K_I$) as well as of Mode II($K_{II}$) based on the piezoelectric constitutive law and fracture mechanics are calculated. In this study, the SIF values measured by MFC sensors are compared with the theoretical results and measured value.
오동진,김명현,Oh, Dong-Jin,Kim, Myung-Hyun 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.6
Fatigue cracks in structural components are the most common cause of structural failure when exposed to fatigue loading. In this respect, fatigue crack detection and structural health assessment are very important. Currently, various smart materials are used for detecting fatigue crack and measurement of SIFs(Stress Intensity Factors). So, this paper presented a measurement of SIFs using MFC(Micro Fiber Composite) sensor which is the one of the smart material. MFC sensor is more flexible, durable and reliable than other smart materials. The SIFs of Mode I(K I) as well as Mode II(K II) based on the piezoelectric constitutive law and fracture mechanics are calculated. In this study, the SIF values measured by MFC sensors are compared with the theoretical results.
고압산소 전처치의 심근 항산화효소 활성 증가 및 허혈-재관류손상 보호 효과
오동진,김영훈,김찬형,박종완,김명석,Oh, Dong-Jin,Kim, Young-Hoon,Kim, Chan-Hyung,Park, Jong-Wan,Kim, Myung-Suk 대한약리학회 1997 The Korean Journal of Physiology & Pharmacology Vol.1 No.6
Myocardial ischemia-reperfusion injury is known to be mediated by reactive oxygen species. The myocardial cell is equipped with endogenous antioxidant defensive system which can be adaptively stimulated by various oxidative stress. It is postulated that an increased oxygen partial pressure induced by hyperbaric oxygenation impose an oxidative stress on the cells, resulting alterations in the endogenous antioxidant system. In this study we investigated the effect of hyperbaric oxygenation on the activities of myocardial antioxidant enzymes and observed whether the hyperbaric oxygenation could protect the ischemia-reperfusion injury of heart. Rats or rabbits were pretreated with hyperbaric $oxygenation(2{\sim}3\;atm\;O_2/1{\sim}3\;hrs/1{\sim}10\;days)$. The changes in activities of major antioxidant enzymes(superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phasphate dehydrogenase), functional recovery and infarct size were observed in the experimentally induced ischemia-reperfused hearts. In the hearts isolated from rats pretreated with $2\;atm\;O_2/1{\sim}2\;hrs$ for 5 days, the functional recovery after reperfusion(20 min) following global ischemia(25 min) was significantly increased without any observable oxygen toxicity. Lactate dehydrogenase release was also significantly reduced in this hyperbaric oxygenated rat hearts. In in vivo regional ischemia(30 min) model of rabbit hearts, pretreatrment with $2\;atm\;O_2/1\;hr$ for 5 days significantly limited the infarct size. Among the myocardial antioxidant enzymes of rat hearts pretreated with the hyperbaric oxygenation, the activities of catalase, superoxide dismutase and glucose-6-phosphatase dehydrogenase were increased, while those of glutathione peroxidase and reductase were not changed. There were lethal cases in the groups of rats exposed to 3 atm $3\;atm\;O_2/2{\sim}3\;hrs$ for 5 days. A lipid-peroxidation product, rnnlondialdehyde was increased in brains and livers of the rats exposed to$2\;atm\;O_2/2{\sim}3\;hrs/5\;days\;and\;3\;atm\;O_2/1\;hr/5days$. The present results suggest that the pretreatment of hyperbaric oxygenation can protect the post-ischemic rererfused hearts in association with a stimulation of the activities of myocardial antioxidant defensive enzymes, and that the hyperbaric oxygenation of $2\;atm\;O_2/1\;hr$for 5 days would be a safe condition which does not produce any oxygen toxicity.
SPIN을 이용한 무선 이동 센서 네트워크의 배치 알고리즘 검증
오동진,박재현,Oh Dong-Jin,Park Jae-Hyun 한국정보처리학회 2006 정보처리학회논문지D Vol.13 No.3
본 논문에서는 최근 많은 연구가 진행되고 있는 무선 센서 네트워크 분야에서 이동 센서 노드의 배치 알고리즘인 DSSA(Distributed Self Spreading Algorithm)와 TBDA(Tree Based Deployment Algorithm)을 모델링 하고, 이들 알고리즘의 안정성과 정확성을 널리 사용되고 있는 모델 검증 도구인 SPIN을 이용하여 검증한다. 그리고 두 알고리즘이 무선 센서 네트워크의 중요사항인 에너지 소비면에서 효율적으로 동작하는지 SPIN 검증 도구를 이용하여 비교분석하고, DSSA에서 발생하는 진동에 대한 보완점을 제시한다. This paper verifies deployment algorithms in wireless sensor networks using SPIN, a widely used model checking tool. In this paper, two deployment algorithms, DSSA(Distributed Self Spreading Algorithm) and TBDA(Tree Based Deployment Algorithm), are verified to check their stability against oscillation as well as energy consumption that is an important factor in wireless sensor networks.
논문 : RFID 시스템에서 다중 태그 인식을 위한 충돌회피 알고리즘의 성능 개선에 관한 연구
오동진 ( Dong Jin Oh ),민병택 ( Byoung Taek Min ),남궁호영 ( Ho Young Namgung ),김대진 ( Dae Jin Kim ),김철성 ( Cheol Sung Kim ) 전남대학교 전자통신기술연구소 2006 전자통신기술논문지 Vol.9 No.1
본 논문에서는 현재 모든 사물에 전자 태그를 부착하여 사물의 정보 및 환경정보까지 감지하여 네트워크에 연결하여 실시간으로 관리하는 유비쿼터스 센서네트워크(USN)에서 다중 태그 인식을 위한 개선된 충돌회피 알고리즘을 제안하고, 이를 RFID(Radio Frequency IDentification) 시스템에 적용하여 다중 태그인식의 모의실험 결과를 보여준다. UHF(860MHz~960MHz) 대역에서 동작하는 수동형-백스캐터 (passive-backscatter)RTF(Reader-Talk-First) RFID 시스템의 물리적, 논리적 요구를 명세하고 있는 EPC(Electronic Product Code)에 기반한 Class 0와 Class 1 프로토콜을 분석하였다. 또한 EPC Class 1 protocol에 기반한 RFID 시스템의 시뮬레이터를 설계하고 구현하였다. 이를 통해 최종적으로 본 논문에서 제안한 충돌회피 알고리즘이 기존의 충돌회피 알고리즘에 비해 더 나은 성능을 보임을 알 수 있었다. In this paper, we propose an improved anti-collision algorithm for multi tag interrogation in ubiquitous sensor network(USN) and show the result of simulation for multi tag interrogation in RFID systems. We have analyzed an EPC protocol which specifies the physical and logical requirements for a passive-backscatter Reader-Talk- First(RTF) RFID system operating in the 860MHz-960MHz frequency range. And We have also designed and implemented the simulator of the RFID system based on the EPC protocol. Finally, We find that proposed algorithm works better than an existing algorithm.
오동진(Dong Jin Oh),이준승(Jun Seung Lee),박지현(Jee Hyun Park),곽귀철(Gue Chul Gawk),강응택(Eung Taek Kang),유석희(Suk Hee Yu) 대한내과학회 1995 대한내과학회지 Vol.48 No.6
N/A Objectives: Prior to the development of effective antihypertensive regimen and renal replacement therapy, malignant hypertension regarded as a bad prognostic disease. Sine 1960 with the early detection of hypertension and the introduction of new potent antihypertensive regimens and renal replacement therapy, there were several reports of etiologic changes and improving survival rates. However there has been a few reports concerning malignant hypertension in 1990s and never reported in Korea so far. The purpose of this study is to know the cause, clinical feature and survival rate of malignant hypertension in Korean, Method: The definition of malignant hypertension is characterized as grade III or IV hypertensive retinopathy according to Keith-Wagener-Barkers classification. we reviewed 107 patients with malignant hypertension who visited our department between 1988 and 1993 retrospectively. Results: The mean age of essential hypertension was 56years, renal lesion 37years, renovascular lesion 45years, and that of unknown cause was 41years, The mean blood pressure of essential hypertension was 209mmHg/128mmHg, renal lesion 194mmHg/120mmHg, renovascular lesion 210mmHg/130mmHg, and that of unknown cause was 183mmHg/125mmHg. The initial serum creatinine of essential hypertension was 2.45±2.51mg/dl, renal lesion 8.10±7.56mg/dl, renovascular lesion 1.95±0.35mg/dl, and that of unknown cause was 15.44±10.24mg/dl. Essential hypertension was diagnosed in 56 cases (53%), secondary hypertension in 40 cases (37%) and unknown cause in 11 cases(10%). The One year patient was 92% and 5 year survival survival 51%. The 5 year patient survival of essential hypertension was 85% and that of secondary hypertension was 86%. The 5year patient survival was 92% in the group of initial serum creatinine <3mg/dl, but 81% in the group of inital serum creatinine >3mg/dl. Ten patients died. Of these, three patients died of cerebrovascular accident, three patients died of hyperkalemia. Other causes of death were pulmonary edema, hepatic encephalopathy, lung cancer, and socioeconomic factor. Conclusion: the main cause of malignant hypertension in Korea was primary hypertension and survival rates were similar to recent other reports.