• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.430-435
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• 2004

Nonhomogeneous Poisson Process is often used to model failure times which occurred in software reliability and hardware reliability models. It can be characterized by its intensity functions or mean value functions. Many parametric intensity models have been proposed to account for the failure mechanism in real situation. In this paper, we propose a Bayesian semiparametric approach based on beta-mixtures. Two real datasets are analyzed.

• 대한예방의학회:학술대회논문집
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• 2003.04a
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• pp.30-37
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• 2003

o Cohort study became the major approach to study of chronic diseases such as CVD and cancer o Cohort can be population-based or volunteer-based o Types of be population-be categorized by source population and selection mechanism o More and more cohort studies involve biological specimens, such as blood, urine, toenail, cheek cells, etc. o Multi-center and multi-national collaboration is an effective way to increase sample size. o Current statistical method typically use time-to-event analysis by Cox proportional hazard model.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.155-160
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• 2005

Computer simulations of a pdp discharges provide unique information necessary for their analysis, unavailable otherwise. Statistical instability of the ramp discharge and the role of exoemission, nature of striations during sustain discharge, physical mechanism responsible for the propagation of the cathode ionization wave, and line loading effects are just a few examples when simulations can be successfully used.

• International Journal of Quality Innovation
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• v.9 no.3
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• pp.71-91
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• 2008

The definition of cycle time is the time from the wafer start to the wafer output. It usually takes one or two months to get the product since customer decides to produce it. The cycle time is a critical factor for customer satisfaction because it represents the response time to the market. Long cycle time reflects the ineffective investment for the capital. The cycle time is very important for foundry because long cycle time will cause customer unsatisfied and the order loss. Consequently, all of the foundries put lots of human source in the cycle time improvement. Usually, we make decisions based on the experience in the cycle time management. We have no mechanism or theory for cycle time management. We do work-in-process (WIP) management based on turn rate and standard WIP (STD WIP) set by experiences. But the experience didn't mean the optimal solution, when the situation changed, the cycle time or the standard WIP will also be changed. The experience will not always be applicable. If we only have the experience and no mechanism, management will not be work out. After interview several foundry fab managers, all of the fab can't reflect the situation. That is, all of them will have an impact period after product mix or utilization varied. In this study, we want to develop a formula for standard WIP and use statistical process control (SPC) concept to set WIP upper/lower limit level. When WIP exceed the limit level, it will trigger action plans to compensate WIP Profile. If WIP Profile balances, we don't need too much WIP. So WIP level could be reduced and cycle time also could be reduced.

• Journal of the Korean Statistical Society
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• v.32 no.2
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• pp.121-150
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• 2003

The National Health Interview Survey (NHIS) is one of the surveys used to assess the health status of the US population. One indicator of the nation's health is the total number of doctor visits made by the household members in the past year, There is a substantial nonresponse among the sampled households, and the main issue we address here is that the nonrespones mechanism should not be ignored because respondents and nonrespondents differ. It is standard practice to summarize the number of doctor visits by the binary variable of no doctor visit versus at least one doctor visit by a household for each of the fifty states and the District of Columbia. We consider a nonignorable nonresponse model that expresses uncertainty about ignorability through the ratio of odds of a household doctor visit among respondents to the odds of doctor visit among all households. This is a hierarchical model in which a nonignorable nonresponse model is centered on an ignorable nonresponse model. Another feature of this model is that it permits us to "borrow strength" across states as in small area estimation; this helps because some of the parameters are weakly identified. However, for simplicity we assume that the hyperparameters are fixed but unknown, and these hyperparameters are estimated by the EM algorithm; thereby making our method Bayes empirical Bayes. Our main result is that for some of the states the nonresponse mechanism can be considered non-ignorable, and that 95% credible intervals of the probability of a household doctor visit and the probability that a household responds shed important light on the NHIS.

• The Journal of Pediatrics of Korean Medicine
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• v.20 no.1
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• pp.15-29
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• 2006

Objective : Based on the Th1/Th2 inbalance hypothesis, we aimed to evaluate the effects of NaesowhajungtongGamibang on serum $interferon{\gamma}$, interleukin-4, interleukin-5, of 19 patients with atopic dermatitis. Materials & Methods: The subjects are consisted of 19 patients with atopic dermatitis, and had been treated with NaesowhajungtongGamibang decoction for 45 days. Serum $IFN-{\gamma}$, IL-4, IL-5 level were checked before and 45 days after treatments. Results: The serum $IFN-{\gamma}$, IL-5, level in patients with atopic dermatitis were slightly decreased compared with normal control group, but had no statistical significance. The serum IL-4, level in patients with atopic dermatitis was slightly increased compared with normal control group, but had no statistical significance. After treatment with NaesowhajungtongGamibang for 45 days, serum $IFN-{\gamma}$, IL-5, level were increased, but had no statistical significance. After treatment with NaesowhajungtongGamibang for 45 days, serum IL-4 level were decreased, but had no statistical significance. Conclusion: This study shows that NaesowhajungtongGamibang decoction had effects were not correspond with Th1/Th2 inbalance hypothesis. Therefore study for other mechanism of NaesowhajungtongGamibang on atopic dermatitis is required.

• The Journal of Engineering Geology
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• v.12 no.2
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• pp.203-214
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• 2002

The statistical model was introduced to satisfy various experimental condition on the sorption of heavy metals (Pb, Cu, Cd, and Zn) by bentonite. The Box-Behnken model designed statistically was applied to determine relative impact among three variables such as pH, HCO$_3$ contents and heavy metal concentrations on the sorption. The SAS program was used to obtain the statistical solution. The statistical surface response analysis indicates that initial concentration of heavy metals and pH have an important effect on the sorption, and bicarbonate is not a serious variable. The sorption capability about heavy metals of bentonite is in the order of Pb>Cu>Zn>Cd. The precipitation as hydroxyl and carbonate complexes of heavy metals was thermodynamically analyzed as major mechanism of sorption under alkaline pHs and high bicarbonate solution. It was found that there is a little difference between the model prediction on the precipitation of heavy metals and the results of batch sorption experiment. The thermodynamic data of the programs have to revise to obtain the best fit condition between the model prediction and the experimental results.

• Earthquakes and Structures
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• v.18 no.5
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• pp.649-665
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• 2020

One of the most important issues in structural systems is evaluation of the margin of safety in low and mid-rise buildings against the progressive collapse mechanism due to the earthquake loads. In this paper, modeling of collapse propagation in structural elements of RC frame buildings is evaluated by tracing down the collapse points in beam and column structural elements, one after another, under earthquake loads and the influence of column removal is investigated on how the collapse expansion in beam and column structural members. For this reason, progressive collapse phenomenon is studied in 3-story and 5-story intermediate moment resisting frame buildings due to the corner and edge column removal in presence of the earthquake loads. In this way, distribution and propagation of the collapse in progressive collapse mechanism is studied, from the first element of the structure to the collapse of a large part of the building with investigating and comparing the results of nonlinear time history analyses (NLTHA) in presence of two-component accelograms proposed by FEMA_P695. Evaluation of the results, including the statistical survey of the number and sequence of the collapsed points in process of the collapse distribution in structural system, show that the progressive collapse distribution are special and similar in low-rise and mid-rise RC buildings due to the simultaneous effects of the column removal and the earthquake loads and various patterns of the progressive collapse distribution are proposed and presented to predict the collapse propagation in structural elements of similar buildings. So, the results of collapse distribution patterns and comparing the values of collapse can be utilized to provide practical methods in codes and guidelines to enhance the structural resistance against the progressive collapse mechanism and eventually, the value of damage can be controlled and minimized in similar buildings.

• Earthquakes and Structures
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• v.18 no.6
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• pp.691-707
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• 2020

One of the most important issues in structural systems is evaluation of the margin of safety in low and mid-rise buildings against the progressive collapse mechanism due to the earthquake loads. In this paper, modeling of collapse propagation in structural elements of RC frame buildings is evaluated by tracing down the collapse points in beam and column structural elements, one after another, under earthquake loads and the influence of column removal is investigated on how the collapse expansion in beam and column structural members. For this reason, progressive collapse phenomenon is studied in 3-story and 5-story intermediate moment resisting frame buildings due to the corner and edge column removal in presence of the earthquake loads. In this way, distribution and propagation of the collapse in progressive collapse mechanism is studied, from the first element of the structure to the collapse of a large part of the building with investigating and comparing the results of nonlinear time history analyses (NLTHA) in presence of two-component accelograms proposed by FEMA_P695. Evaluation of the results, including the statistical survey of the number and sequence of the collapsed points in process of the collapse distribution in structural system, show that the progressive collapse distribution are special and similar in low-rise and mid-rise RC buildings due to the simultaneous effects of the column removal and the earthquake loads and various patterns of the progressive collapse distribution are proposed and presented to predict the collapse propagation in structural elements of similar buildings. So, the results of collapse distribution patterns and comparing the values of collapse can be utilized to provide practical methods in codes and guidelines to enhance the structural resistance against the progressive collapse mechanism and eventually, the value of damage can be controlled and minimized in similar buildings.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.279-284
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• 2004

Red tide(harmful algae) in the Korean Coastal Waters has a given a great damage to the fishery every year. However, the aim of our study understands the influence of meteorological factors (air and water tempaerature, precipitation, sunshine, solar radiation, winds) relating to the mechanism of red tide occurrence and monitors red tide by satellite remote sensing, and analyzes the potential area for red tide occurrence by GIS. The meteorological factors have directly influenced on red tide formation. Thus, We want to predict and apply to red tide formation from statistical analyses on the relationships between red tide formation and meteorological factors. In future, it should be realized the near real time monitoring for red tide by the development of remote sensing technique and the construction of integrated model by the red tide information management system (the data base of red tide - meteorological informations).