• 한국컴퓨터정보학회논문지
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• 제17권5호
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• pp.49-57
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• 2012

본 논문에서는 P2P스트리밍에서 peer간 연결 정보를 이용하는 방법을 기반으로 topology 최적화를 연구한다. 제안하는 방법은 mesh-network에서 사용된 link와 사용되지 않은 link의 수로 peer의 업로드 용량을 추정하는 방법을 기반으로 한다. 연결된 link의 정보를 사용하는 기존 방법은 peer의 자원 관리 측면에서 메시지 과부하를 줄이는데 효과적이다. 하지만 업로드 대역폭이 고려되지 않는 topology를 구성할 우려가 있다. 또한 서버에 가까운 peer에서 네트워크 오류 발생시 네트워크 전송성능이 저하될 수 있다. 본 논문에서는 기존 방법의 단점을 보완하는 방법을 제안한다. 기존 방법과 제안하는 방법을 시뮬레이션 하고 결과를 비교 분석한다.

• Nuclear Engineering and Technology
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• 제47권2호
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• pp.204-211
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• 2015

Probabilistic safety assessment (PSA) has had a significant role in quantitative decision-making by finding design and operational vulnerabilities and evaluating cost-benefit in improving such weak points. In particular, it has been widely used as the core methodology for risk-informed applications (RIAs). Even though the nature of PSA seeks realistic results, there are still "conservative" aspects. One of the sources for the conservatism is the assumptions of safety analysis and the estimation of failure frequency. Surveillance, diagnosis, and prognosis (SDP), utilizing massive databases and information technology, is worth highlighting in terms of its capability for alleviating the conservatism in conventional PSA. This article provides enabling techniques to solidify a method to provide time- and condition-dependent risks by integrating a conventional PSA model with condition monitoring and prognostics techniques. We will discuss how to integrate the results with frequency of initiating events (IEs) and probability of basic events (BEs). Two illustrative examples will be introduced: (1) how the failure probability of a passive system can be evaluated under different plant conditions and (2) how the IE frequency for a steam generator tube rupture (SGTR) can be updated in terms of operating time. We expect that the proposed model can take a role of annunciator to show the variation of core damage frequency (CDF) depending on operational conditions.

• 암석학회지
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• 제25권4호
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• pp.325-334
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• 2016

한반도에서는 크고 작은 지진이 꾸준히 발생하고 있음을 역사문헌과 계기지진 관측 자료를 통해 알 수 있다. 본 연구에서는 역사지진과 계기지진 자료를 이용해 지리정보시스템(GIS)의 공간분석 결과, 북한의 평양지역이 지진으로부터 가장 위험한 지역으로 결정되었다. 평양은 북한의 수도로서 인구와 구조물의 밀집도가 높아 지진뿐만 아니라 재해로 인해 큰 위험에 처할 수 있다. 502년 평양에서 발생한 규모 6.7의 지진을 토대로 지진동 지도를 작성한 결과, 0.24 g보다 높은 지진동을 느낄 수 있는 지역이 평양지역의 약 51.1%를 차지한다. 또한 통계청 자료에 의하면 북한은 우리나라보다 재해로부터 열악한 환경에 처해 있음을 확인할 수 있었다. 이번 연구결과는 향후 북한을 포함한 우리나라의 포괄적인 지진재해예측 연구에 유용한 정보로 사용될 수 있다.

• 한국식품위생안전성학회지
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• 제26권4호
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• pp.302-307
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• 2011

One of the most important objectives of post-marketing monitoring of dietary supplements is the early detection of unknown and unexpected adverse events (AEs). Several causality algorithms, such as the Naranjo scale, the RUCAM scale, and the M & V scale are available for the estimation of the likelihood of causation between a product and an AE. Based on the existing algorithms, the Korea Food & Drug Administration has developed a new algorithm tool to reflect the characteristics of dietary supplements in the causality analysis. However, additional work will be required to confirm if the newly developed algorithm tool has reasonable sensitivity and not to generate an unacceptable number of false positives signals.

• 한국지반환경공학회 논문집
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• 제11권8호
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• pp.49-55
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• 2010

병렬터널의 이격거리가 근접할수록 응력집중으로 인하여 필라(pillar)의 파괴 위험이 큰 만큼 필라의 응력 검토 및 필라의 강도를 고려한 필라의 안정성 평가는 병렬터널의 이격거리 검토 시 매우 중요한 사항이다. 본 연구에서는 필라의 안정성을 구하는 방법 중 하나인 수치해석의 요소크기를 검토하여 필라부 안정성 검토에 대한 체계적인 분석을 제안하였다. 그 결과, 강도응력비는 요소크기에 따른 영향이 크게 없었고, 강도강소법에 의한 안전율은 요소가 작을수록 안전율이 작게 나왔다. 특히 지반이 풍화암인 경우 요소크기에 대한 안전율 값 차이가 크므로 지반이 불량한 경우 요소의 크기를 작게하는 것이 안정적인 결과를 나타냈다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5829-5834
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• 2015

Objective: To describe and analyze the epidemiological characteristics of lung cancer mortality in China from 1991 to 2013, forecast the future five-year trend and provide scientific evidence for prevention and management of lung cancer. Materials and Methods: Mortality data for lung cancer in China from 1991 to 2013 were used to describe epidemiological characteristics. Trend surface analysis was applied to analyze the geographical distribution of lung cancer. Four models, curve estimation, time series modeling, gray modeling (GM) and joinpoint regression, were performed to forecast the trend for the future. Results: Since 1991 the mortality rate of lung cancer increased yearly. The rate for males was higher than that for females and rates in urban areas were higher than in rural areas. In addition, our results showed that the trend will continue to increase in the ensuing 5 years. The mortality rate increased from age 45-50 and peaked in the group of 85 years old. Geographical analysis indicated that people living in northeast China provinces and the coastal provinces in eastern China had a higher mortality rate for lung cancer than those living in the centre or western Chinese provinces. Conclusions: The standardized mortality rate of lung cancer has constantly increased from 1991 to 2013, and been predicted to continue in the ensuing 5 years. Further efforts should be concentrated on education of the general public to increase prevention and early detection. Much better prevention and management is needed in high mortality areas (northeastern and eastern parts of China) and high risk populations (45-50-year-olds).

• Asian Pacific Journal of Cancer Prevention
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• 제15권7호
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• pp.3021-3027
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• 2014

Background: The multidrug resistance 1 gene (MDR1) C3435T polymorphism has been demonstrated to influence the P-glycoprotein (P-gp) activity level which is related to inflammation and carcinogenesis. This meta-analysis was performed to estimate the association between the MDR1 C3435T polymorphism and the risk of gastric cancer (GC) and peptic ulcer (PU). Materials and Methods: A literature search was conducted with PubMed, Embase and the Cochrane library up to November 2013. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. Data were analyzed using Review Manager (Version 5.2), and Stata package (version 12.0) for estimation of publication bias. Results: Six case-control studies were included, of which five were for GC and two for PU. Overall, no evidence was found for any association between the MDR1 C3435T polymorphism and the susceptibility to GC and PU. In the stratified analysis by H. pylori infection status, stage and histology classification of GC, and PU type, there was still no significant association between them. Conclusions: This meta-analysis suggested that the MDR1 C3435T polymorphism is not associated with susceptibility to GC and PU. Large and well-designed studies are warranted to validate our findings.

• Asian Pacific Journal of Cancer Prevention
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• 제14권5호
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• pp.3045-3050
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• 2013

Purpose: Hepatic resection is arguably the preferred treatment for huge hepatocellular carcinoma (H-HCC). Estimating the remnant liver volume is therefore essential. This study aimed to evaluate the feasibility of using computer-assisted volumetric analysis for this purpose. Methods: The study involved 40 patients with H-HCC. Laboratory examinations were conducted, and a contrast CT-scan revealed that 30 cases out of the participating 40 had single-lesion tumors. The remaining 10 had less than three satellite tumors. With the consensus of the team, two physicians conducted computer-assisted 3D segmentation of the liver, tumor, and vessels in each case. Volume was automatically computed from each segmented/labeled anatomical field. To estimate the resection volume, virtual lobectomy was applied to the main tumor. A margin greater than 1 cm was applied to the satellite tumors. Resectability was predicted by computing a ratio of functional liver resection (R) as (Vresected-Vtumor)/(Vtotal-Vtumor) x 100%, applying a threshold of 50% and 60% for cirrhotic and non-cirrhotic cases, respectively. This estimation was then compared with surgical findings. Results: Out of the 22 patients who had undergone hepatectomies, only one had an R that exceeded the threshold. Among the remaining 18 patients with non-resectable H-HCC, 12 had Rs that exceeded the specified ratio and the remaining 6 had Rs that were < 50%. Four of the patients who had Rs less than 50% underwent incomplete surgery due to operative findings of more extensive satellite tumors, vascular invasion, or metastasis. The other two cases did not undergo surgery because of the high risk involved in removing the tumor. Overall, the ratio of functional liver resection for estimating resectability correlated well with the other surgical findings. Conclusion: Efficient pre-operative resectability assessment of H-HCC using computer-assisted volumetric analysis is feasible.

• The Journal of Asian Finance, Economics and Business
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• 제4권3호
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• pp.5-17
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• 2017

This study extends research into whether disclosure of corporate and financial information is associated with firms' costs of equity capital. This study sets out to examine empirically the determinants of corporate disclosure in the annual reports of 37 largest and most liquid firms listed on Kazakhstan Stock Exchange (KASE) in Kazakhstan. It also reports the results of the association between company-specific characteristics and disclosure of the sample companies. Based on the analysis of existing empirical research, the disclosure index has been constructed and regression analysis of the influence of the disclosure index on the cost of equity capital has been conducted. The obtained results show that the received findings correlate with foreign empirical studies, and the disclosure index in this sample has a negative impact on the cost of equity capital. Using cost of equity capital estimates derived from capital asset pricing model, we find that firms with higher levels of financial transparency are associated with significantly lower costs of equity capital. Economic theory assumes that by increasing the level of corporate reporting, firms not only increase their stock market liquidity, but also decrease the investors' estimation risk, arising from uncertainty about future returns and payout distributions. The results show that firms on the Kazakhstan market can reduce their cost of equity capital by increasing the level of their voluntary corporate disclosures.

• Environmental Analysis Health and Toxicology
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• 제5권3_4호
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• pp.47-56
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• 1990

Smoking damages nonsmoker's health who have been exposed to passive smoking as well as smoker's own health. Passive smoking can cause serious health damage to particular groups, such as the old aged, children and pregnant women. The purpose of this study is to investigate the relationship between nicotine concentrations in environmental tobacco smoke (ETS) and urinary cotinine concentrations of nonsmokers exposed to ETS, and to provide basic information related to health risk assessment. The results of this study were summarized as follows: 1. When 180 cigarrette were smoked during S hours (high concentrations exposure) in 132 m$^3$chamber, mean concentrations of nicotine in ETS showed 263.52 $\mu\textrm{g}$/m$^3$${\pm}$51.93. When 45 cigarretts were smoked (low concentrations exposure), it was 69.43${\pm}$8.96 $\mu\textrm{g}$/m$^3$. 2. The urinary cotinine concentrations of each times (0, 2.5, 5, 17 and 24 hours) in nonsmokers ranged from 0.27∼12.52 ng/ml in high concentrations exposure and 0.22∼2.28 ng/ml in low concentrations exposure. Mean while the total urinary cotinine concentrations during 24 hours ranged from 11.62∼31.65 ng/ml in high concentrations exposure and 3.45∼5.64 ng/ml in low concentrations exposure. 3. The correlation equation and coefficient between cotinine concentrations in nonsmokers' urine (y) and nicotine concentrations in ETS (x) was y=0.421+0.0171x and 0:875 (p<0.01) respectively, 4. The quantity of nonsmokers' smoking exposure by passive smoking can be assumed as based on the estimation of nicotine concentrations in ETS by measuring cotinine concentrations of nonsmokers' urine.