• Journal of the Korean Data and Information Science Society
• /
• 제4권
• /
• pp.109-120
• /
• 1993

Using a noninformative prior and a gamma prior, the Bayesian predictive density and the prediction intervals for a future observation or the p-th order statistic of n' future observations from the Burr distribution have been obtained. In additions, we examine the sensitivities of the results to the choice of model.

• 한국경영과학회지
• /
• 제18권1호
• /
• pp.71-78
• /
• 1993

A Baysian approach is proposed is estimating the mission failure rates by criticalities. A mission failure which occurs according to a Poisson process with unknown rate is assumed to be classified as one of the criticality levels with an unknown probability. We employ the Gamma prior for the mission failure rate and the Dirichlet prior for the criticality probabilities. Posterior distributions of the mission rates by criticalities and predictive distributions of the time to failure are derived.

• Journal of the Korean Data and Information Science Society
• /
• 제20권5호
• /
• pp.933-939
• /
• 2009

The bivariate data in clinical research fields often has two types of failure times, which are mark variable for the first failure time and the final failure time. This paper showed how to generate bootstrap data to get Bayesian estimation for the joint distribution of bivariate survival times. The observed data was generated by Frank's family and the fake date is simulated with the Gamma prior of survival time. The bootstrap data was obtained by combining the mimic data with the observed data and the simulated fake data from the observed data.

• Journal of the Korean Data and Information Science Society
• /
• 제10권1호
• /
• pp.147-154
• /
• 1999

Using a noninformative prior and an inverted gamma prior, the Bayesian predictive density and the prediction intervals for a future observation or the p - th order statistic of n' future observations from the censord Pareto model have been obtained. In additions, numerical examples are given in order to illustrate the proposed predictive procedure.

• Journal of the Korean Data and Information Science Society
• /
• 제15권1호
• /
• pp.273-284
• /
• 2004

Bayes estimation of parameters is considered for two independent exponential distributions with ordered means. Order restricted Bayes estimators for means are obtained with respect to inverted gamma, noninformative prior and uniform prior distributions, and their asymptotic properties are established. It is shown that the maximum likelihood estimator, restricted maximum likelihood estimator, unrestricted Bayes estimator, and restricted Bayes estimator of the mean are all consistent and have the same limiting distribution. These estimators are compared with the corresponding unrestricted Bayes estimators by Monte Carlo simulation.

• International Journal of Reliability and Applications
• /
• 제2권1호
• /
• pp.49-56
• /
• 2001

In this paper we consider empirical Bayes estimation of the hazard rate and survival probabilities with right censored data under the assumption that the hazard function is constant over the period of observation and the prior distribution is gamma. We provide an estimator of the first derivative of the prior moment generating function that converges at each point to the true value in $L_2$ and use it to obtain, easy to compute, asymptotically optimal estimators under the squared error loss function.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권16호
• /
• pp.7103-7110
• /
• 2015

The present study was conducted to investigate the effect of ${\gamma}$-radiation alone or combined with a cytotoxic drug, simvastatin, on viability and cell cycling of a myeloma cell line. P3NS1 myeloma cells were treated with the selected dose of simvastatin ($0.1{\mu}M/l$) 24 hours prior to ${\gamma}$-irradiation (0.25, 0.5 and 1Gy). The cell viability, induction of apoptosis, cell death, cell cycling, generation of ROS, and expression of P53, Bax, Bcl2, caspase3, PARP1 and Fas genes were estimated. The results indicated that simvastatin ($0.1{\mu}M/l$) treatment for 24 hours prior to ${\gamma}$-irradiation increased cell death to 37.5% as compared to 4.81% by radiation (0.5Gy) alone. It was found that simvastatin treatment before irradiation caused arrest of cells in G0/G1 and G2/M phases as assessed using flow cytometry. Interestingly, simvastatin treatment of P3NS1 cells increased the intracellular ROS production and decreased antioxidant enzyme activity with increased P53, Bax and Caspase3 gene expression while that of Bcl2 was decreased. Consequently, our results indicated that pre-treatment with simvastatin increased radio sensitivity of myeloma tumor cells in addition to apoptotic effects through an intrinsic mitochondrial pathway.

• Biomedical Engineering Letters
• /
• 제8권4호
• /
• pp.383-392
• /
• 2018

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

• 한국응용약물학회:학술대회논문집
• /
• 한국응용약물학회 1995년도 춘계학술대회
• /
• pp.127-127
• /
• 1995

The present study was conducted to examine the effect of recombinant bovine somatotropin(${\gamma}$ bST), which was administered to cow to promote milk production, on bST levels in milk. Fourteen cows were divided into two groups: 1) control cows received neither y bST nor vehicle, 2) treated cows were administered twice at two-week interval with 500mg ${\gamma}$ bST each cow by subcutaneous injection. Milk samples were taken on day 0 (prior to injection), day 7 (7 days after 1st injection), day 21 (7 days after 2nd injection) and day 35 (21 days after 2nd injection).

• 한국식품과학회지
• /
• 제49권6호
• /
• pp.659-667
• /
• 2017

본 연구는 in vitro에서 나린진과 나린제닌의 항산화 활성을 평가하고, in vivo에서 BALB/c 마우스에 나린진과 나린제닌을 7일 동안 경구투여 한 후 6Gy의 감마선을 조사시켜 24시간 뒤 감마선 조사로 인한 세포 손상 및 산화적 스트레스에 대한 방사선 예방효과를 검토하였다. 나린진과 나린제닌의 항산화 활성평가에서 나린제닌이 나린진보다 ABTS 제거 활성 및 FRAP을 유의적으로 증가시켜 아글리콘 형태인 나린제닌이 글리코사이드 형태의 나린진보다 항산화 능력이 뛰어난 것을 확인하였다. 감마선 조사 전 나린제닌을 투여 한 군이 감마선 조사군에 비해 비장 지수, 흉선 지수 및 백혈구 수치가 증가하여 조혈 면역계 손상에 대해 보호효과가 있음을 확인하였다. 나린제닌을 투여 후 감마선을 조사한 군의 ALT와 AST가 감마선 조사군에 비해 유의적으로 감소하여 간세포 손상에 대한 예방효과를 확인하였다. 감마선 조사 전에 나린제닌을 투여한 군의 지방질과산화는 감마선 조사군에 비해 유의적으로 낮게 나타남을 보였으며, XO는 감마선 조사군에 비해 유의적으로 감소하여 방사선에 의한 장해를 감소시킨 것으로 판단할 수 있다. 감마선 조사 전 나린제닌을 투여한 군의 GSH와 항산화 효소의 활성은 감마선 조사군에 비해 유의적으로 증가하여 생체 내에 항산화 활성을 회복시켰다. 이 상의 결과를 통해 방사선 조사 전에 나린제닌의 투여는 방사선에 의한 세포 손상과 산화적 스트레스에 대해 보호 효과가 있어 방사선보호제로 유용하게 사용될 수 있다.