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        • KCI등재후보

          직업적 망간 폭로에 있어서 뇌자기공명영상의 의의

          정해관 대한자기공명의과학회 1998 Investigative Magnetic Resonance Imaging Vol.2 No.1

          망간은 체내 필수원소의 하나이며 주로 간과 뇌의 기저핵게 축적되며 간을 통하여 배설된다. 망간은 체내 대사가 매우 빠르기 때문에 직업적 망간 폭로를 측정하는데 어려움이 있다. 특히 용접공과 같이 망간 폭로가 간헐적이거나 불규칙한 경우에는 혈중 및 요중 망간과 같은 기존 생체폭로지표로는 장기간에 걸친 폭로량을 정확하게 반영하기 힘들다. 뇌자기공명영상이 대두됨에 따랄 뇌내에 축적된 망간을 영상으로 확인하는 것이 가능하게 되었다. 초기에는 만성간부전 및 장기간에 걸친 정맥영양주입환자 등에서 뇌기저부의 고신호간도 소견이 보고되었다. 망간은 상자성 물질로 뇌자기공명영상에서 T1 이완시간을 단축시켜 T1 강조영상에서 고신호강도를 나타난다. 망간축적에 따른 고신호강도는 주로 담창구, 흑질, 피간 및 뇌하수체 등에서 나타난다. 저자들은 최근까지 국내 및 국외에서 직업적 및 비직업적으로 망간에 폭로된 사람에서 보고된 뇌자기공명영상소견을 수집하여 분석하였다. 우선 T1강조영상에서 관찰되는 고신호 강도와 연령, 성별, 직업적 망간 폭로 및 신경학적 이상 유무간의 관계를 분석하였다. 생물학적 폭로지표와 고신호강도간의 관계도 분석하였다. 고신호강도와 뇌내 망간축적, 신경세포손상 및 신경학적 이상간의 관계에 대한 문헌들을 분석하였다. T1강조영상에서 나타나는 고신호강도는 뇌내 망간축적 정도를 반영한다. 이러한 관계를 이용하여 신호강도를 분석하므로써 뇌내 망간축적 정도를 추정할수 있다. 뇌내 망간축적은 기저핵의 신경세포손상을 초래한다. 그러나 신경학적 이상은 비교적 단기간에 걸친 망간 축적과는 무관하게 보인다. 이는 신경학적 이상소견은 마간의 누적축적량과 관련되어 있기 때문인것으로 추정된다. 뇌자기 공명영사에서 관찰되는 고신호강도 소견은 표적 장기의 망간적 축적량을 반영하는데는 충분하지 못한 것으로 보인다. 따라서이러한 놔자기공명영상의 특성 및 비용-효과적인 측면을 고려할 대 망간폭로집안에서의 망간폭로정도를 추정하기 위하여 놔자기공명영상을 사용하는 것은 바람직하지 않다고 보인다. 그러나 망간과 관련된 건강장해가 의심되는 파킨슨증 환자에서 망간폭로를 확인 및 추정하는 데에는 매우 유용하게 활용할 수 있다. Manganese is an essential element in the body. It is mainly deposited in the liver and to a lesser degree in the basal ganglia of the brain and eliminated through the bile duct. Rapid turnover of managanese in the body makes it difficult to evaluate the manganese exposure in workers, esecially in those with irregular or intermittent exposure, like welders. Therefore, conventional biomarkers, including blood and urine manganese can provide only a limited information about the long-tern or cumulative exposure to manganese. Introduction of magnetic resonance imaging (MRI) made a progress in the assessment of manganese exposure in the medical conditions related to manganese accumulation, e. g. hepatic failure and long-term total parenteral nutrition. Manganese shortens spin-lattice(T1) relaxation time on MRI due to its paramagnetic property, resulting in high signal intensity (HSI) on T1-weighted image(T1W1) of MRI. Manganese deposition in the brain, therefore, can be visualizedas an HSI in the globus pallidus, the substantia nigra, the putamen and the pituitary. clinical and epidemiologic studies regarding the MRI findings in the cases of occupational and non-occupational manganese exposure were reviewed. relationships between HSI on T1W1 of MRI and age, gender, occupational manganese exposure, and neurological dysfunction were analysed. Relationships betwen biological exposure indices and HSI on MRE werealso reviewed. Literatures were reviewed to establish the relationships between HSI, Manganese deposition in the brain, pathologic findings, and neurological dysfunction. HSI on T1W1 of MRI reflects regional manganese deposition in the brain. This relationship enables an estimation of regional manganese deposition in the brain by analysing MR signal intensity. Manganese deposition in the brain can induce a neuronal loss in the basal ganglia but functional abnormality is supposed to be related to the cumulative exposure of manganese in the brain, use of brain MRI for the assessment of exposure in a group of workers seems to be hardly rationalized, while ti can be a useful adjunct for the evaluation of manganese exposure int he cases with suspected manganese-related health problems.

        • KCI등재후보

          구조로봇에 적합한 장애물 회피 알고리즘 ELA의 실험적 검증

          정해관,현경학,김수현,곽윤근 한국로봇학회 2009 로봇학회 논문지 Vol.4 No.2

          In this paper, we provide experimental results and verification for obstacle avoidance algorithm 'ELA(Emergency Level Around)', which is applicable to rescue robots. ELA is a low level intelligence-based obstacle avoidance algorithm, so can be used in fast mobile robots requiring high speed in operation with little computational load. Constructed system for experiments consist of laptop, sensors, peripheral devices and mobile robot platform VSTR(Variable Single-tracked Robot) to realize predetermined scenarios. Finally, experiment was conducted in indoor surroundings including miscellaneous things as well as dark environment to show fitness and robustness of ELA for rescue, and it is shown that VSTR navigates endowed area well with real-time obstacle avoidance based on ELA. Therefore, it is concluded that ELA can be a candidate algorithm to increase mobility of rescue robots in real situation.

        • ELA: 가변 형상 구조로봇의 자율주행을 위한 실시간 장애물 회피 기법

          정해관,현경학,김수현,곽윤근 한국로봇학회 2008 로봇학회 논문지 Vol.3 No.3

          We propose a novel real-time obstacle avoidance method for rescue robots. This method, named the ELA(Emergency Level Around), permits the detection of unknown obstacles and avoids collisions while simultaneously steering the mobile robot toward safe position. In the ELA, we consider two sensor modules, PSD(Position Sensitive Detector) infrared sensors taking charge of obstacle detection in short distance and LMS(Laser Measurement System) in long distance respectively. Hence if a robot recognizes an obstacle ahead by PSD infrared sensors first, and judges impossibility to overcome the obstacle based on driving mode decision process, the order of priority is transferred to LMS which collects data of radial distance centered on the robot to avoid the confronted obstacle. After gathering radial information, the ELA algorithm estimates emergency level around a robot and generates a polar histogram based on the emergency level to judge where the optimal free space is. Finally, steering angle is determined to guarantee rotation to randomly direction as well as robot width for safe avoidance. Simulation results from wandering in closed local area which includes various obstacles and different conditions demonstrate the power of the ELA.

        • SCOPUSKCI등재
        • KCI등재후보

          고속 주행용 실외 경비로봇을 위한 구동 메커니즘

          정해관,고두열,우춘규,곽윤근 한국로봇학회 2009 로봇학회 논문지 Vol.4 No.2

          In this paper, a new driving mechanism of security robotswhich should overcome obstacles with stability even though movingin high speed is introduced. The driving mechanism has spring-based suspension and two wheels positively necessary to overcome obstacles. From the driving mechanism, it is mainly discussed how we can decrease overshoot and impulse occurred when the robot is in the process of overcoming obstacles. Finally, design parameters of the driving mechanism which guarantees stable motion while overcoming obstacles is deduced based on simulation results. Experiments are also followed to demonstrate how well the manufactured system works in its early stage of the practical use.

        • 일부 지역 도로관리 종사자에서 발견된 흉부 X선상 소음영 소견에 관한 조사

          정해관,임현술,최익한,이원재,이현경 동국대학교 경주대학 1993 東國論集 Vol.12 No.-

          Authors examined 135 workers(133 males and 2 females) employed in a local road construction and maintenance office lacated in the Pohang area to investigate the presence of pneumoconiosis cases among them. Examination consisted of questionnaire survey, physical examination and chest radiograph. Results are as follows ; 1. Of 135 workers, 8 cases(5.9%) were found to have small opacities of category 0/1 or more on chest radiogtaph. These cases were all males and prevalence was highest in group with age 50 or more(11.1% 3 out of 27 workers) and in froup with 5 to 9 years of employment(9.5%, 4 out of 42 workers). Small Opacities were found only in field workers(8.9%, 8 out of 90 workers) and prevalence of small opacities by job title was 8.8% in overload watchmen(3 out of 34 workers), 8.2% in road sweepers, road repair and maintenance workers(5 out of 56 workers). 2. Prevalence of small opacities on chest radiograph was higher in dusty, outdoor jobs than non-dusty jobs and the difference was statistically significant(P<0.05) 3. There was no statistically significant difference between those with radiological appearance of small opacities and normal subjects in age, educational level, duration of employment, previous dust exposure, past history of respiratory illness and clinical symptoms(P>0.05). 4. Of 8 cases with small opacities on chest radiograph, 1 case had small opacity of category 1/0(s/s) and the other 7 cases had small opacities of category 0/1. Two cases had past history of pulmonary tuberculosis, but radiologic findings were not consistent with tuberculosis. Two cases with less than 5 years of employment had previous history of dust exposure. Although specific etiologic factors were not clear with this study alone, authors suspected that specific geological factors in the Pohang area(soils rich in diatomaceous earth, bentonite and fullers' earth etc.) may have some role in development of small opacities. Above results suggests that follow up investigation for further development and progression of pneumoconiosis and effective measures to prevent dust exposure of road workers are needed.

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