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졸-겔법으로 합성된 폴리이미드/실리카 복합체의 환경적 물성에 관한 연구
박성수,홍성수,이성환,김성완,박재현,김지경,박희찬 한국환경과학회 2003 한국환경과학회지 Vol.12 No.4
Two types of polyimide/silica composite films were prepared using sol-gel method through hydrolysis and polycondensation of tetraethoxsilane(TEOS) with the polyamic acid(PAA) and end-capped PAA solution. Sample were characterized by the means of differential thermogravimetry, X-ray diffractometry, scanning electron microscopy, universal test, impedance analyzer, chemical resistance test, etc. All of the PAA/silanol solutions heat-treated at 300℃ for 6h were transformed to polyimide/silica composites. It has been demonstrated that the properties of polyimide/silica composites were affected by the amount of silica addition and the bond type existed between polyimide and silica.
폐결핵 환자 혈청에서 수용성 Interleukin 2 수용체 및 Adenosine Deaminase 활성도에 관한 연구
고정희,박성규,백상현,박찬권,박병수,안진영,최우석,박정규 충남대학교 의과대학 지역사회의학연구소 1993 충남의대잡지 Vol.20 No.1
Interleukin-2 (IL-2) induces T cell proliferation in an autocrine manner and provides a means by which antigen triggered T cells can be clonally expanded in vitro. During the following activation, the activity of IL-2 is mediated by specific high affinity IL-2 binding membrane receptors which are expressed shortly after activation. In this process, a 42 KD-fragment (soluble IL-2R) is continuously cleaved off and circulates as a soluble marker of T lymphocyte activation. Elevated level of soluble IL-2R has been identified in the serum of patients with malignant autoimmune and allergic disorders, systemic parasitic infection, undergoing graft versus host disease, acute or chronic lymphocytic leukemia and HIV-infection. ADA (adenosine deaminase) completes the process of differentiation of T cell and is essential for progression of T cell maturation. Therefore level of ADA is to correlated with magnitude of T cell immune response. The fact that expression of sIL-2R and ADA activity increases in peripheral blood T-lymphocytes of patients with active pulmonary tuberculosis suggests that T cell activation might have a major role in the pathogenesis of pulmonary tuberculosis. In order to evaluate the T cell immune response in pulmonary tuberculosis, we measured the serum concentration of sIL-2R and ADA activity in 17 patients with current pulmonary tuberculosis, 10 chronic inactive pulmonary tuberculosis, 10 as normal controls. (1) Current pulmonary tuberculosis had significantly higher levels of sIL-2R (237.24±95.47)when compared with those of inactive tuberculosis (78.6±11.06). and the control (68.17±15.4) group. (2) ADA activity in current pulmonary tuberculosis was significantly increased (34.41±20.63) when compared with those of inactive tuberculosis (24.7±14.36) and control (17.65± 5.94) group. (3) There was good correlation between sIL-2R concentration and ADA activity in serum in current pulmonary tuberculosis group. (4) sIL-2R concentration and ADA activity was decreased significantly 6 months after anti-tuberculosis drug medication. In conclusion, sIL-2R concentration and ADA activity in serum in current pulmonary tuberculosis group was increased when compared with those of inactive pulmonary tuberculosis and the control group. By the way, T cell mediated immune response was enhanced in current pulmonary tuberculosis, but in inactive chronic pulmonary tuberculosis who had treated by antituberculosis drug medication, the concentration of sIL-2R and ADA activity was nearly normal.
한상우,유진홍,권순석,김성훈,박지찬,홍은정,최경성,박용완,장준희,안지원,박유경,강지영,박상미,신완식 대한감염학회 2004 감염과 화학요법 Vol.36 No.5
We experienced a 25 year-old male patient with typhoid fever complicated with massive hemoptysis. Pulmonary complication in typhoid fever is very rare and to our knowledge, there has been no report of hemoptysis as a main cause of death with this disease. We herein report a rare case of typhoid fever.
FEA와 다이나모메터를 이용한 자동차 디스크 브레이크의 열적 거동에 관한 연구
박범식,손영지,장성규,전언찬 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-
While braking cars, a large amount of energy is taken into the brake system in a short period of time. This leads to some problems ; cracking of the disc, non-uniform wear of pad and disc, fade. Thus it is important to measure the contact thermal behaviour precisely between disc and pad. The measurements must be considered to design the brake system. The paper describes methods to analysis the problem of the thermal behavior on the ventilated disc with ANSYS-a program of FEA and a brake dynamometer. According to this way, the paper can present the error between the data by the dynamometer and the results of analysis by ANSYS.
다단계 수리체계의 성능평가를 위한 폐쇄형 대기행렬 네트워크 모형
박찬우,김창곤,이효성 한국경영과학회 2000 한국경영과학회지 Vol.25 No.4
In this study we consider a spares provisioning problem for repairable items in which a parts inventory system is incorporated. If a machine fails, a replacement part must be obtained at the parts inventory system before the failed machine enters the repair center. The inventory policy adopted at the parts inventory system is the (S,Q) policy. Operating times of the machine before failure, order in lead times and repair times are assumed to follow a two-stage Coxian distribution. For this system, we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of machines at each station and they probability that a part will wait at the parts inventory system. For the analysis of the proposed system, we model the system as a closed queueing network and analyze it using a product-form approximation method. A recursive technique as well as an iterative procedure is used to analyze the sub-network. Numerical tests show that the approximation method provides fairly good estimation of the performance measure of interest.
박찬우,이효성 한국경영과학회 2002 한국경영과학회지 Vol.27 No.4
We study multi-component production/inventory system in which individual components are made to meet various demand types. We assume that the demands arrive according to a Poisson process, but there is a fixed probability that a demand requests a particular kit of different components. Each component is produced by a flow line with several stations in which the processing times of each station follow a two-stage Coxian distribution. The production of each component is operated by an independent base-stock with blocking. We assume that the time needed to assemble final products follows a general distribution and the capacity of an assembling facility is sufficiently large. The objective of this study is to obtain key performance measures such as the distribution of the number of each orders for each final product and the mean time of fulfilling a customer order. The basic principle of the proposed approximation methods is to decompose the original system into a set of subsystems, each subsystem being associated with a flow line. Each subsystem is analyzed in isolation using a method. As iterative procedure is then used to determine the unknown parameters of each subsystem. Numerical results show that the accuracy of the approximation method is acceptable.
박희찬,강효경,김병찬,박성수 釜山大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.56 No.-
카올린으로부터 미립 일루미나 분말을 합성하였다. 황산용액을 이용하여 액상침전법으로 알루미나를 추출하였다. 알루미나 추출에 미치는 황산농도, 반응온도 및 반응시간의 영향을 조사하였다. 이 과정에서 수화 황산알루미늄이 용출액으로부터 석출되었다. 이때 석출제로는 에탄올을 사용하였다. 이 석출물을 가영하여 미립 알루미나 분말을 얻을 수 있었다. DTA, SEM, TEM 및 XRD를 이용하여 분말의 특성을 조사하였다. Fine alumina was synthesized from kaolin. The alumina was prepared by liquid phase precipitation method using H?SO? solution. The effects of acid concentration, reaction temperature and reaction time on alumina extraction were investigated. Using an ethanol as precipitating agent, hydrated aluminum sulfate was precipitated from leach liquor. Fine alumina powder was obtained by calcining the precipitate. DTA, SEM, TEM and XRD were employed to characterize the powder.