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      • KCI등재
      • KCI등재후보

        특수건강진단의 건강관리구분과 그 개선방안에 관한 연구

        이승한,이원철,김형아,장성실 大韓産業醫學會 1994 대한직업환경의학회지 Vol.6 No.2

        The findings of special medical examinations are not infrequently summarized in the form of health classification. This procedure seems valuable for the protection of workers' health from personal health as well as public health point of view, because health classification of workers provides occupational health workers with birds eye view informations in terms of medical, placement and educational procedures, which are to be followed after medical examinations. In this study, the authors have reviews the existing systems of special medical examinations and health classifications in different countries and those recommended by international organizations for the purpose of improving the current system in Korea. The important issues covered in this review in relation to health classification of workers included the categories of diseases, the examination and laboratory tests, the criteria for health level classification and the health instructions to be given at each health levels. It was found that the current health classification system in Korea could be featured as follows: 1. Special medical examinations are always carried out in combination with general medical examinations, contributing to the detection of risk factors of occupational diseases. 2. The selection of examinees is always made on the basis of work environment monitoring, often resulting in the underdetection of exposed workers. 3. Even if the test items are properly selected according to the principles of occupational medicine, further review is required in the light of recent advances in the pathogenesis as well as early changes of occupational diseases and epidemiologic principles. 4. The criteria for the classification of health levels are to be reviewed on the basis of clinical eqidemiology. 5. The health instructions covered only medical and placement aspects, failing to introduce the concept of health promotion.

      • KCI등재후보

        Stem cell과 Myeloperoxidase가 스티렌, 하이드로퀴논 및 트리클로로에틸렌에 의한 림프구의 자매염색분체 교환과 소핵체 유도에 미치는 영향

        이경재,김형아,신민정,성재혁,박정일,한훈,이세훈 대한산업의학회 2001 대한직업환경의학회지 Vol.13 No.3

        목적 : 스티렌, 하이드필퀴논 및 트리클로로에틸렌 (TCE)이 사람의 stem cell과 human myeloperoxidase (MPO)에 의해 대사성 활성화되는 지를 규명하고자 스티렌, 하이드로퀴논 및 TCE에 사람의 stem cell 또는 MPO 효소의 첨가가 이들 화학물질에 의한 자매염색분체교환(SCE)과 소핵체 (MN) 빈도에 미치는 영향을 관찰하였다. 방법 : 건강한 남자의 전혈에서 림프루를 분리하여 72시간동안 이중배양하되 배양개시 24시간만에 0.05mM 하이드로퀴논, 1.50 mM 스티렌, 혹은 1.50mM TCE를 전체용량이 30 ㎕가 되도록 아세톤에 희석하여 배양액에 주입하였고 대조군은 아세톤으로 처리하였다. 화학물질 처리 후 즉시 1.3×106 및 2.6×106 cells/ml 농도의 제대혈액으로부터 나온 stem cell 세포액의 상층액이나 1.0 및 2.0 unit의 human myeloperoxidase를 H2O2와 함께 첨가하였다. SCE분석을 위한 배양액에는 배양종료 2.5시간 전에 colchicine을 가한 후 수확하여 Giemsa염색을 하여 metaphase 세포에서 SCE빈도를 분석하였다. MN분석을 위한 배양액에는 배양개시 44시간만에 cytochalasin-B를 가하였고 acridine orange 염색 후 이핵체에서 MN수를 분석하였다. 결과 : 1. stem cell이나 MPO 자체는 SCE나 MN의 빈도에 영향을 미치지 않았다. 2. stem cell이나 MPO는 스티렌에 의해 유도되는 SCE의 빈도를 용량-반응관계로 유의하게 증가시켰고, MN빈도의 경우 step cell이나 MPO에 의해 증가되는 경향이 있었으나 2.0 unit MPO를 첨가한 경우에만 첨가하지 않은 경우에 비하여 유의하게 증가하였다. 3. 하이드로퀴논은 stem cell이나 MPO가 없는 상태에서도 대조군에 비하여 SCE빈도가 대조군에 비하여 높았다. stem cell이나 MPO는 하이드로퀴논에 의한 SCE 빈도를 용량 반응관계로 유의하게 증가시켰지만, MN의 경우에는 증가시키는 경향만 있을 뿐 유의한 차이는 아니었다. 4. TCE자체는 SCE나 MN빈도를 증가시키지 않았다. stem cell은 1.3 ×106 및 2.6 × 106 cells/ml 농도 모두에서 SCE빈도를 유의하게 증가시켰고 MPO는 2.0 unit농도에서만 유의하게 증가시켰다. stem cell이나 MPO모두 TCE에 의한 MN빈도를 증가시키는 경향이 있었으나 유의한 차이는 아니었다. 결론 : 저자들은 스티렌, 하이드로퀴논, 및 트리클로로에틸렌에 의해 유도되는 자매염색분체교환과 소핵체의 빈도가 사람의 stem cell이나 myeloperoxidase에 의해 증가됨을 발견하였으며, 이러한 결과는 myeloperoxidase가 이들 물질의 대사성활성화에 관여함을 암시하고, 또한 아마도 이 물질들의 골수독성과 관련이 있는 것이라고 제시된다. Objectives : The objective of this study was to identify the possible role of stem cell and myeloperoxidase (MPO) in the metabolic activation of styrene, hydroquinone and trichloroethylene, by investigating the effects of stem cell from umbilical cord blood and MPO on the frequency of sister chromatid exchange (SCE) and micronuclei (MN) induction in cultured human peripheral lymphocytes exposed to hese chemicals. Methods : Islated lymphocytes from whole blood were cultured for 72 hours. The cells were treated with 1.50 mM styrene, 50 μM hydroquinone and 1.50 mM trichloroethylene dissolved with acetone (30㎕ in total volume) at 24 hours after the beginning of culture. Control group was treated with acetone only. Immediately after adding these chemicals, 1.3×106 cells/ml and 2.6×106 cells/ml stem cell/ml stained with Giemsa's solution, and acridine orange for sister chromatid exchange, and for micronucleus analysis, respectively. Results : The results were as follows: 1) Myeloperoxidase and stem cell did not significantly affect the frequencies of SCE or MN in the control group. 2) The frequency of SCE or MN with exposure to styrene did not different from control in the absence of stem cell or MPO. Sister chromatid exchange induced by styrene was significantly increased by adding stem cell or MPO in dose-dependent relationship. The frequency of MN induced by styrene significantly increased in the presence of 2.0 unit MPO. 3) The frequency of SCE was significantly increased with exposure to hydroquinone than acetone treated control in the absence of stem cell or MPO. Sister chromatid exchange induction by hydroquinone significantly increased dose-dependently in the presence of stem cell or MPO. There was a tnendency of increase of the MN frequency induced by hydroquinone in the presence of stem cell or MPO, but not significant. 4) It was found that trichloroethylene itself did not increase SCE or MN frequency. Frequency of SCE induced by trichloroethylene was significantly increased with adding stem cell (low and high) and 2.0 unit MPO. Even though them cell or MPO increased the frequency of MN of lymphocyte exposed to trichloroethylene, the difference was not significant. Conclusions : Authors found that the frequencies of both sister chromatid exchange and micronucleus induced by styrene, hydroquinone, and trichloroethylene were increased significantly with the treatment of stem cell or myeloperoxidase. It was suggested that myeloperoxidase may therefore play an important role in the metabolic activation of styrene, hydroquinone, and trichloroethylene and myeloperoxidase probably be involved in the myelotoxicity of these chemicals.

      • 섭동계수를 갖는 단일 자기부상 시스템의 강인한 제어기 개발에 관한 연구

        이형기,변기식,신춘식,탁한호 釜山工業大學校 1991 論文集 Vol.33 No.-

        A EMS(Electro Magnet Suspension) nonlinear system is linearized by using Taylor series expansion around nominal point. A method of stability analysis for a low-order characteristic equation with perturbed coefficients is proposed. A PID controller to the linearized EMS system is designed by the method. Computer simulations are carried out in the system with the controller for various masses.

      • KCI등재

        미소균열 탐상을 위한 자기광학소자를 이용한 비파괴탐상법의 제안과 적용

        이형노,박한주,庄子 哲雄 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.2

        항공기나 대형 플랜트 등의 경년구조물에 있어서 제조 및 설계 혹은 작업환경 등에 의해 발생하는 미소결함은 응력부식파괴로 이어지는 결정적인 원인으로 알려져 있다. 따라서 제조단계에서의 결함의 검출뿐만 아니라 운전개시 후에 있어서도 비파괴검사에 기초를 둔 정기적인 건전성평가가 요구된다. 특히 구조물내의 미소균열 평가는 구조 건전성 평가에 있어서 중요한 과제라 할 수 있다. 자기광학소자를 이용한 비파괴탐상법은 균열부근의 누설자속에 의한 자구 및 자벽의 변화를 이용하여 균열정보를 화상형태로 얻는다. 그러므로 빠른 탐상속도와 결과데이터 해석의 용이 그리고 실시간적으로 탐상결과를 획득할 수 있다는 장점을 지니고 있다. 본 논문은 자기광학소자를 이용한 새로운 비파괴적 탐상법을 제안하고, 본 탐상법을 이용하여 구조물에 존재하는 표면결함의 검출가능성 및 균열깊이의 평가를 실증하였다. 표면결함을 갖는 시험편과 파이프의 내면에 존재하는 피로균열을 대상으로 실험을 실시한 결과, 표면결함의 위치 및 2차원적 형상을 화상형식으로 얻을 수 있음을 증명하였다. 또한 피로시험중의 시험편을 대상으로 균열발생 및 균열진전과정을 평가를 통하여 원격탐상의 가능성을 제시하였다. Micro-defects induced by design and production failure or working environments are known as the cause of SCC(Stress Corrosion Cracking) in aged structures. Therefore, the evaluation of structural integrity based on micro-cracks is required not only a manufacturing step but also in-service term. So we introduce a new nondestructive inspection method using the magneto-optical film to detect micro-cracks. The method has some advantage such as high testing speed, real time data acquisition and the possibility of remote sensing by using of a magneto-optical film that takes advantages of the change of magnetic domains and domain walls. This paper introduces the concept of the new nondestructive inspection method using the magneto-optical film, also proves the possibility of this method as a remote testing system under oscillating load considering application on real fields by applying the method to four types of specimens.

      • KCI등재
      • 가변구조 제어시스템의 Luenberger Observer에 관한 연구

        탁한호,이형기,박양수,권세현 釜山工業大學校 1991 論文集 Vol.33 No.-

        This paper presents an analysis of the stste observer-based robust speed control of a self-controlled synchonous motor (SCSM). A Variable structure control (VSC) technique is utilized to achieve robust (paramater-insensitive) characteristics. The speed and acceleration signals required for the implementation of the variable structure speed control (VSSC) are dynamically estimated with stste observer. One kind observer-the Luenberger full order observer-air explored in this paper. The results obtained that Luenverger observers do estimate the system ststes accurately when the system parameters vary. The design methods and the simulation results presented demonstrable the potential of the proposed scheme.

      • 數種의 增量劑 粒度와 增量比率에 따른 尿素樹脂合板의 接着 特性

        楊翰承,尹炯雲,李弼宇 서울대학교 농과대학 농업개발연구소 1993 서울대농학연구지 Vol.18 No.2

        The purpose of this research was to evaluate and to examine the substitutional feasibility of paper sludge extender instead of wheat flour. As the extending materials, taro flour, paper sludge, wood flour and wheat were selected and dried at 103±2℃ during 24 hours in the drying oven and pulverized into three levels(-50∼+100, -100∼+200, -200∼mesh). The extenders were mixed with urea formaldehyde resin in the ratio of 10, 20 and 30%. After plywoods were manufactured by the above extended ratios, dry and wet shear strength were examined. The results obtained at this research were summarized as follows : 1) In 10% extionsion on -50∼+100 mesh particle size, paper sludge showed the highest dry and wet shear strength among the extenders. 2) As 20% extension, wheat showed the highest value. 3) the shear strength was affected by the particle size and extending ratios, and the shear strength extended by paper sludge powder was sensitively varied with particle sizes and extending ratios. 4) The shear strength extended by taro and wheat flour were less affected by the particle size of extender. Therefore, the particle size of extender would be considered along the extention ratios and extender types.

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