• Asian Pacific Journal of Cancer Prevention
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• v.15 no.14
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• pp.5571-5575
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• 2014

Background: The ability to predict the survival time of breast cancer patients is important because of the potential high morbidity and mortality associated with the disease. To develop a predictive inference for determining the survival of breast cancer patients, we applied a novel Bayesian method. In this paper, we propose the development of a databased statistical probability model and application of the Bayesian method to predict future survival times for White Hispanic female breast cancer patients, diagnosed in the US during 1973-2009. Materials and Methods: A stratified random sample of White Hispanic female patient survival data was selected from the Surveillance Epidemiology and End Results (SEER) database to derive statistical probability models. Four were considered to identify the best-fit model. We used three standard model-building criteria, which included Akaike Information Criteria (AIC), Bayesian Information Criteria (BIC), and Deviance Information Criteria (DIC) to measure the goodness of fit. Furthermore, the Bayesian method was used to derive future survival inferences for survival times. Results: The highest number of White Hispanic female breast cancer patients in this sample was from New Mexico and the lowest from Hawaii. The mean (SD) age at diagnosis (years) was 58.2 (14.2). The mean (SD) of survival time (months) for White Hispanic females was 72.7 (32.2). We found that the exponentiated Weibull model best fit the survival times compared to other widely known statistical probability models. The predictive inference for future survival times is presented using the Bayesian method. Conclusions: The findings are significant for treatment planning and health-care cost allocation. They should also contribute to further research on breast cancer survival issues.

• International Journal of Oral Biology
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• v.33 no.4
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• pp.217-221
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• 2008

Bicuculline is one of the most commonly used $GABA_A$ receptor antagonists in electrophysiological research. Because of its poor water solubility, bicuculline quaternary ammonium salts such as bicuculline methiodide (BMI) and bicuculline methbromide are preferred. However, a number of studies have shown that BMI has non-$GABA_A$ receptor-mediated effects. The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) is implicated in the processing of nociceptive signaling. In this study, we investigated whether BMI has non-GABA receptor-mediated activity in Vc SG neurons using a whole cell patch clamp technique. SG neurons were depolarized by application of BMI ($20{\mu}M$) using a high $Cl^-$ pipette solution. GABA ($30-100{\mu}M$) also induced membrane depolarization of SG neuron. Although BMI is known to be a $GABA_A$ receptor antagonist, GABA-induced membrane depolarization was enhanced by co-application with BMI. However, free base bicuculline (fBIC) and picrotoxin (PTX), a $GABA_A$ and $GABA_C$ receptor antagonist, blocked the GABA-induced response. Furthermore, BMI-induced membrane depolarization persisted in the presence of PTX or an antagonist cocktail consisting of tetrodotoxin ($Na^+$ channel blocker), AP-5 (NMDA receptor antagonist), CNQX (non-NMDA receptor antagonist), and strychnine (glycine receptor antagonist). Thus BMI induces membrane depolarization by directly acting on postsynaptic Vc SG neurons in a manner which is independent of $GABA_A$ receptors. These results suggest that other unknown mechanisms may be involved in BMI-induced membrane depolarization.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.505-511
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• 2014

PURPOSE. The purpose of this study was to assess the effect of systemically administered oxytocin (OT) on the implant-bone interface by using histomorphometric analysis and the removal torque test. MATERIALS AND METHODS. A total of 10 adult, New Zealand white, female rabbits were used in this experiment. We placed 2 implants (CSM; CSM Implant, Daegu, South Korea) in each distal femoral metaphysis on both the right and left sides; the implants on both sides were placed 10 mm apart. In each rabbit, 1 implant was prepared for histomorphometric analysis and the other 3 were prepared for the removal torque test (RT). The animals received intramuscular injections of either saline (control group; 0.15 M NaCl) or OT (experimental group; $200{\mu}g/rabbit$). The injections were initiated on Day 3 following the implant surgery and were continued for 4 subsequent weeks; the injections were administered twice per day (at a 12-h interval), for 2 days per week. RESULTS. While no statistically significant difference was observed between the two groups (P=.787), the control group had stronger removal torque values. The serum OT concentration (ELISA value) was higher in the OT-treated group, although no statistically significant difference was found. Further, the histomorphometric parameter (bone-to-implant contact [BIC], inter-thread bone, and peri-implant bone) values were higher in the experimental group, but the differences were not significant. CONCLUSION. We postulate that OT supplementation via intramuscular injection weakly contributes to the bone response at the implant-bone interface in rabbits. Therefore, higher concentrations or more frequent administration of OT may be required for a greater bone response to the implant. Further studies analyzing these aspects are needed.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.253-263
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• 2006

Purpose: Recently, dental implant systems have been widely used for the treatment of the extraction site, but we have been confronted with many limitations in esthetics, phonetics and function. Transitional implants(TI) were developed as a method of providing fixed provisional restorations during conventional implant healing. Until now, little data have been provided on korean transitional implants. The purpose of this study is to evaluate the implant placement site histologically after 4 weeks and 8 weeks. Materials and Methods : Test group( IntermetzzoTM MEGAGEN, KOREA) and control group(Mini Drive Lock, Intra Rock, U.S.A.) were immediately placed in interseptal or interproximal bone of beagle dog after mandibular premolars extraction, and had a healing period with non-submerged state but without loading, Both TI surfaces were composed of rough surfaces. Results: In the test group, the average percentage of BIC were respectively 39.40%(SD7.35) after 4 weeks and 44.05%(16.76) after 8 weeks, and In the control group were 50.75%(1.48) and 59.40%(0.00). Discussion: We evaluated the initial ability of the osseointegration of TI through this study. Because TI is placed with a conventional implant simultaneously and loaded immediately, the ability of osseointegration is a very important factor for the success of TI during the initial healing phase. Conclusion: The results of the histological evaluation of these two groups were similar to those mentioned in other studies for osseointegration of implant.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.339-344
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• 2007

Statement of problem. Various anodic oxidation techniques can be applied to dental implant surfaces. But the condition for optimal anodized surfaces has not been described yet. Purpose. The purpose of this investigation was to compare an implant that was oxidized by another method with $TiUnite^{TM}$ through resonance frequency analysis and histomorphometry. Material and methods. Turned (control), $TiUnite^{TM}$ and another oxidized fixtures, which used $Ca^{2+}$ solution for anodic oxidation, were placed in the tibiae of 5 New Zealand White rabbits. The bone responses were evaluated and compared by consecutive resonance frequency analysis once a week for 6 weeks and histomorphometry after a healing period of 6 weeks. Results. At the first week, both oxidized implants showed significantly higher implant stability quotient (ISQ) values than the control. No significant differences in resonance frequency analysis were found between the two oxidized groups for 6 weeks. The means and standard deviations of bone-to-implant contact (BIC) ratios were $71.0{\pm}4.2$ for $TiUnite^{TM}$, $67.5{\pm}10.3$ for the $Ca^{2+}$-based oxidation fixture, $22.8{\pm}6.5$ for the control. Both oxidized implants were significantly superior in osseointegration to the turned one. There was, however, no statistically significant difference between the two oxidized implants. Conclusion. $TiUnite^{TM}$ and the $Ca^{2+}$-based oxidation fixture showed superior early bone response than the control with respect to resonance frequency analysis and histomorphometry. No significant differences between the oxidized groups, however, were found in this investigation using the rabbit tibia model.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.2
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• pp.123-130
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• 2005

Many of the molecular and genotypic events taking place at the osteoblast cell level during bone-implant integration are still largely unknown. The objective of this study was to examine expression patterns of TGF-$\beta$ and IGF-I related genes during bone-implant integration. Titanium implants with machined surface were placed into 8 rabbit tibias. At 3rd, 7th, 14th, 28th day after implantation, the expression pattern of TGF-$\beta$ and IGF-I genes in bone with or without implant was examined using reverse transcriptase-polymerase chain reaction (RT-PCR). At the same time, histomorphometric analysis was evaluated, respectively. The bone-to-implant contacts (BIC) of experimental groups were 5.2%, 6.2%, 6.6%, 24.6% at 3rd, 7th, 14th, 28th day. This indicated that newly formed bone increased at the implant surface in bone marrow space after implantation. The expressions of TGF-$\beta$ and IGF-I were higher in implantation groups than untreated control groups during all experimental days. The increased expression of TGF-$\beta$ and IGF-I genes may be associated with the increased bone-to-implant contact. This result provided the evidence for existing biologic differences in tissue response after implantation and helped us to understand molecular biologic processes in tissue-implant integration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.645-652
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• 2016

The statistical modeling of input random variables is necessary in reliability analysis, reliability-based design optimization, and statistical validation and calibration of analysis models of mechanical systems. In statistical modeling methods, there are the Akaike Information Criterion (AIC), AIC correction (AICc), Bayesian Information Criterion, Maximum Likelihood Estimation (MLE), and Bayesian method. Those methods basically select the best fitted distribution among candidate models by calculating their likelihood function values from a given data set. The number of data or parameters in some methods are considered to identify the distribution types. On the other hand, the engineers in a real field have difficulties in selecting the statistical modeling method to obtain a statistical model of the experimental data because of a lack of knowledge of those methods. In this study, commonly used statistical modeling methods were compared using statistical simulation tests. Their advantages and disadvantages were then analyzed. In the simulation tests, various types of distribution were assumed as populations and the samples were generated randomly from them with different sample sizes. Real engineering data were used to verify each statistical modeling method.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.4-4
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• 2017

수문자료의 빈도해석은 자료의 독립성(independence)와 정상성(stationarity)를 가정하여 이뤄진다. 그러나 관측 수문자료에서 비정상성 현상이 발생하고 있다는 사실이 관측되면서 수문자료에 대한 비정상성 빈도해석에 대한 필요성도 커지고 있다. 본 연구의 목적은 수문자료의 빈도해석에서 가장 널리 사용되고 있는 Gumbel 및 GEV 분포에 대한 비정상성 빈도해석 모형을 개발하는 것으로, 이를 위해 비정상성 Gumbel과 GEV 모형의 매개변수를 시간에 따라 변하는 형태로 정의하였다. 비정상성 Gumbel 및 GEV 모형의 정확도를 알아보기 위해 비정상성 모형과정상성 모형을 이용하여 Monte Carlo 모의실험을 수행하였다. 모의실험은 다양한 조건의 재현기간, 표본크기, 매개변수 조건을 고려하여 수행되었다. 그 결과 비정상성 모형의 오차는 비교적 표본크기가 클 때 가장 작은 것으로 나타났다. 또한 복잡한 매개변수의 조합을 가지는 비정상성 모형은 모두 동일한 경향성을 가질 때 가장 작은 오차를 보이는 것으로 나타났다. 비정상성 GEV 모형의 경우는 확률수문량 산정에 음(-)의 형상 매개변수가 큰 영향을 끼치는 것으로 나타났다. 또한 본 연구에서는 비정상성 조건에서 다양하게 존재하는 비정상성 모형 중 어떠한 모형이 주어진 자료에 대해 가장 적절한 모형인지 결정하기 위해 모의실험을 수행하였다. 널리 적용되고 있는 AIC, BIC, likelihood ratio test에 대해 정상성 및 비정상성 Gumbel 모형을 이용하여 모의실험을 수행한 결과, AIC가 비정상성 모형 중 적정 모형 선택에 가장 효과적인 것으로 나타났다. 개발된 비정상성 Gumbel 및 GEV 모형의 적용성을 알아보기 위해 우리나라 연최대강우 자료에 적용한 결과, 위치 매개변수에 시간항을 고려하는 Gumbel 모형이 최적모형으로 가장 많이 선택되는 것으로 나타났다. 따라서 현재 우리나라의 연최대강우자료 중 경향성이 나타나는 자료에 대해서는 위치 매개변수가 시간에 따라 변하는 특성이 가장 많이 나타나고 있는 것으로 판단된다.

• The Korean Journal of Applied Statistics
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• v.31 no.6
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• pp.721-732
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• 2018

Latent class analysis (LCA) is an important tool to explore unseen latent groups in multivariate categorical data. In practice, it is important to select a suitable set of variables because the inclusion of too many variables in the model makes the model complicated and reduces the accuracy of the parameter estimates. Dean and Raftery (Annals of the Institute of Statistical Mathematics, 62, 11-35, 2010) proposed a headlong search algorithm based on Bayesian information criteria values to choose meaningful variables for LCA. In this paper, we propose a new variable selection procedure for LCA by utilizing posterior probabilities obtained from each fitted model. We propose a new statistic to measure the adequacy of LCA and develop a variable selection procedure. The effectiveness of the proposed method is also presented through some numerical studies.

• The Journal of Korean Institute of Information Technology
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• v.16 no.11
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• pp.77-84
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• 2018

In this paper, the circular polarization microstrip patch antenna using the T-junction power divider is proposed. The operating frequency of the proposed antenna is ISM band of 2.4GHz and the circular polarization is induced by feeding a phase difference of $90^{\circ}$ in two edges. The structure of the antenna consists of a general patch and a T-junction power divider. Furthermore, to optimize the proposed antenna, it is analyzed the reflection coefficient, the axial ration and the radiation pattern. The impedance bandwidth of the antenna is observed to be 40MHz within a range of 2.39 to 2.43GHz, similarly, the axial ratio bandwidth is observed having the bandwidth of about 12MHz in 2.398 to 2.410GHz range. The radiation pattern of the antenna is seen to be right circular polarization. Furthermore, the gain of the antenna is observed to be 2.04 and 3.4dBic at XZ and YZ-plane, respectively.