• Title, Summary, Keyword: MRL

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A Nonparametric Small Sample Estimator of Mean Residual Life

  • Farrokh Choobineh;Park, Dong-Ho
    • Journal of the Korean Statistical Society
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    • v.19 no.1
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    • pp.80-87
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    • 1990
  • In reliability and life testing the mean residual life (MRL) of an item plays a significant role. While there has been a great deal of discussion on the theoretical aspects of the MRL, good estimators of MRL have been difficult to obtain. In this paper we propose a new estimator of the MRL of items at a given age, which is especially good for a small sample. The new estimator compares favorably with the empirical MRL estimator for small samples.

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The Role of Fas in Radiation Induced Apoptosis in vivo (방사선에 의한 Apoptosis에서 Fas의 역할)

  • Kim, Sung-Hee;Seong, Jin-Sil;Seong, Je-Kyung
    • Radiation Oncology Journal
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    • v.20 no.3
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    • pp.246-252
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    • 2002
  • Purpose : It has been recognized that interaction of the Fas : Fas ligand plays an important role in radiation-induced apoptosis. The purpose of this study was to investigate the role of Fas mutation in radiation-induced apoptosis in vivo. Materials and Method : Mice with mutations in Fas, $MRL/Mpj-Fas^{Ipr}$, and its normal control, MRL/Mpj, were used in this study. Eight-week old male mice were given whole body radiation. After irradiation, the mice were killed and their spleens were collected at different time intervals. Tissue samples were stained with hematoxylin-eosin and the numbers of apoptotic cells were scored. Regulating molecules of apoptosis including p53, Bcl-2, Bax, $Bcl-X_L,\;and\;Bcl-X_S$ were also analyzed by Western blotting. Results : At 25 Gy irradiation, the level of apoptosis reached the peak value at 8 hr after radiation and recovered to the normal value at 24 hr after radiation in MRL/Mpj mice. In contrast, the peak apoptosis level appeared at 4 hr after radiation in $MRL/Mpj-Fas^{Ipr}$. At 8 hr after radiation, the levels of apoptosis in MRL/Mpj mice and $MRL/Mpj-Fas^{Ipr}$ mice were $52.3{\pm}7.8\%\;and\;8.0{\pm}8.6\%$, respectively (p<0.05). The expression of apoptosis regulating molecules, p53, $Bcl-X_L\;and\;Bcl-X_S$, increased in MRL/Mpj mice in response to radiation; p53 with a peak level of 3-fold at 8 h, $Bcl-X_L$ with a peak level of 3.3-fold at 12 h, and $Bcl-X_S$ with a peak level of 3-fold at 12 h after 25 Gy radiation. Bcl-2 and Bax did not show significant change in MRL/Mpj mice. However in $MRL/Mpj-Fas^{Ipr}$ mice, the expression levels of p53, Bcl-2, Bax, $BCl-X_L\;and\;BCl-X_S$ showed no significant change. Conclusion : The level of radiation-induced apoptosis was lower in Fas mutated mice, Ipr, than in control mice. This seemed to be related to the lack of radiation-induced p53 activation in the Ipr mice. This result suggests that Fas plays an important role in radiation-induced apoptosis in vivo.

The Study on the Mean Residual Life Estimation of Reliability Data under Random Censoring (임의절단 하에서 신뢰성 자료의 평균잔여수명 추정에 대한 연구)

  • Lee, Mi-Sook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.6
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    • pp.1997-2003
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    • 2010
  • Mean Residual Life (MRL) function plays a very important role in the area of engineering, medical science, survival studies, social sciences, and many other fields. Specially, in the reliability study of technical systems, the MRL estimation of a component is very important because the sudden stop of a system brings a serious problem. So, many simulation studies of MRL estimation have been done considering various situation variables. In this paper, four estimators of MRL are proposed under random censoring and their performances re compared through bias and Mean Square Error (MSE) by Monte Carlo simulation.

The fluctuation and the rigidity study of F-actin filaments in a confined space

  • Park, Myung-Chul;Youli Li;Cyrus R. Safinya;Kim, Mahn-Won
    • Proceedings of the Korean Biophysical Society Conference
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    • pp.67-67
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    • 2003
  • Filamentous actin (F-actin) is a two stranded long helix that performs structural function in eukaryotic cells. F-actin had been assembled from Alexa-labeled G-actin and had been confined in microchannel. The fluctuation of single filaments was observed by fluorescence optical microscopy. We measured Tangent-tangent Correlation Function G(s) (where s is the distance along the contour of the chain), which tells us the confining wall effect of wormlike semi-flexible polymers as well as the flexural rigidity, such as persistence length.

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Production, isolation and characterization of the antibiotic from Pseudomonas aeruginosa 3120 (Pseudomonas aeruginosa 3120으로부터 항생물질의 생산,분리 및 특성)

  • Ko, Hack-Ryong;Chun, Hyo-Kon;Kho, Yung-Hee;Sung, Nack-Kie
    • Applied Biological Chemistry
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    • v.36 no.6
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    • pp.428-433
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    • 1993
  • A strain that inhibited the growth of Pellicularia sasakii was isolated from the soil and identified as Pseudomonas aeruginosa 3120. A dark brownish antibiotic, MRL3120 isolated and purified from the culture broth of P. aeruginosa 3120 was soluble in ethylacetate, chloroform and methanol, and it was active against gram-positive and negative bacteria as well as fungi. The structure of MRL3120 was identified as a chelate compound consisting of two N-methyl-N-thioformyl-hydroxylamine and a copper ion by the analysis of UV, IR, and EI-MS spectra and other physico-chemical properties and supposed to have a structure of fluopsin C related compound. Addition of $CuSO_4$ into the fermentation medium containing soybean meal increased antifungal activity but no activity was found in the presence of EDTA (0.1%, v/v). However antibiotic MRL3120 was not produced in the fermentation medium containing soytone instead of soybean meal but it was rapidly produced by the addition of $CuSO_4$.

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The monitoring of some heavy metals in oriental mineral medicines (광물성 생약 중 중금속의 모니터링)

  • Han, Eunjung;Chung, Jaeyeon;Park, Kyungsu;Kang, Inho;Kang, Sinjung;Kim, Yunje
    • Analytical Science and Technology
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    • v.21 no.6
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    • pp.480-486
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    • 2008
  • This paper reports on the monitoring results of some heavy metals (Pb, Cd, As and Hg) in oriental mineral medicines. Levels of Pb, Cd and As were determined using the acid digestion method and ICP-MS. Hg levels were determined using the gold amalgamation method and Automatic mercury analyzer (AMA). The results indicated that, in the case of Pb, 25.81% (24 cases) of the samples were over MRL (5 mg/kg). Pb levels in Calamina, Pumex, and Cinnabaris exceeded MRL (5 mg/kg). In the case of Cd, 9.68% (17cases) of the samples were over MRL (0.3 mg/kg). Cd levels in Calamina, Pumex and Cinnabaris were exceeded MRL (0.3 mg/kg). In case of As, 24.73% (23 cases) of samples exceeded MRL (3 mg/kg). As levels in Calamina, Lithargyrum, Vermilionum, Cinnabaris and Chalcocitum exceeded MRL (3 mg/kg). In the case of Hg, it was shown that the 76.34% (78 cases) of the samples exceeded MRL (0.2 mg/kg). Hg levels in almost all the samples exceeded MRL (0.2 mg/kg). These results led us to recommend that the domestic commercial law to be legislated to ensure the quality estimation and safety of oriental mineral medicines.

A Study on the Methodology of Manufacturing Readiness Levels(MRLs) 8 of Manufacturing Readiness Assessment(MRA) (제조성숙도평가 MRL8 평가 방법론에 관한 연구)

  • Lee, Ji Hyeog;Jung, Yeong Tak;Lim, Jae Seong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.609-619
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    • 2017
  • A Manufacturing Readiness Assessment (MRA) was adapted to prevent the probable ascending expense, poor quality, and delay from the development to production phase and assess the level of manufacturing readiness in 2012. Consequently, there are positive effects on improving the quality to identify the manufacturing risks during the production of military supplies and manage the issues in advance. On the other hand, because the appraisee is becoming accustomed to preparing for MRA checklists tailoring, it was found to intensify the MRA points more than before, which damages the goal of the MRA. This paper proposes the quantitative MRA methodology using MWV (Manufacturing Readiness Level 8 Weighted Value) to define and measure the HOM8, DOM8, ICOM8, and M8RA to reflect the history of MRA, the difficulties of MRA checklists, the intrinsic cruciallity and risk assessment of program, which can overcome the problems mentioned before. This paper shows the MWV of four weapon system programs to be carried out and an analysis of the proposed MRL 8 methodology.

A Proposal of Round Specimen for the Determination of Crack Arrest Toughness (균열정지 인성치결정을 위한 원형시편의 제안)

  • 이억섭;김상철;송정일;이규철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.5
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    • pp.1472-1478
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    • 1991
  • 본 연구에서는 Rectangular Computer Tension(CT) 시편을 수정하여 만든 표준 시편인 MRL-CLWL시편(material research laboratorycrack line wedge loaded specimen )으로 균열정지 인성치를 결정하였다. 그리고 CT시편과 같은 효과를 갖는 Newman등 이 제안한 round compact tension(RCT)시편을 수정한 Round-CLWL 시편으로 균열정지인 성치를 결정하여 상호 비교평가하였다. Round-CLWL 시편은 시편제작시 round-bar를 절단하여 시편으로 가공할 수 있으므로 가공성이 좋으며 따라서 가공비가 적게 든다. 특히 균열 위치 및 방향을 임의로 선택하여 가공하기가 용이하므로 방향성이 있는 소 재의 균열정지 인성치를 결정하는 데 매우 편리한 시편이라 생각된다. 본 논문에서 는 Round-CLWL 시편으로 $K_{1a}$ 값을 계산하는데 필요한 형상계수를 결정하였으며, Polymethylmethacrylate(PMMA)를 사용하여 Round-CLWL 시편 채택의 타당성 확인을 위 한 MRL-CLWL과 Round-CLWL 시편 채택의 타당성 확인을 위한 MRL-CLWL과 Round-CLWL시 편의 $K_{1a}$결정 실험을 하였다.하였다.