• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.629-636
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• 2001

Network is changed from voice-based network into multimedia-based network by development of communication technology and multimedia service. We need a large bandwidth for multimedia service. The optical fiber is a more suitable medium than existing copper-based cable for large bandwidth. But, it is so expensive than copper-based cable. So, Minimizing total cost becomes a more important concept. In order to construct a minimum cost network, we have to consider existing conduits in network. On the other hand, optical fiber network allows that larger amount of traffic can be transmitted than copper-based network does. However, a failure of a node or link can make a serious damage to the network service. Thus, we have to get multiple paths to support continuous service even if a loss of failure occurs in some point of the network. The network survivability problem is to design the network that can provide reliable service to customers anytime with minimum total cost. In an existing solution of the network survivability problem with conduits, a conduit is considered only one time. But, the conduit is reusable if the network satisfies the required survivability. Proposed algorithm can more effectively considered already existed conduit. Network survivability and edge cost is predetermined. The proposed algorithm finds the best solution by conduit sharing within the limits of network survivability. According to the simulation result, the proposed method can decrease 7% of total cost than an existing method by effective conduits adaption.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.47-55
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• 2011

Hemorrhagic shock is a cause of one third of death resulting from injury in the world. Early diagnosis of hemorrhagic shock makes it possible for physician to treat successfully. The objective of this paper was to select an optimal classifier model using physiological signals from rats measured during hemorrhagic experiment. This data set was used to train and predict survival rate using artificial neural network (ANN) and support vector machine (SVM). To avoid over-fitting, we chose the best classifier according to performance measured by a 10-fold cross validation method. As a result, we selected ANN having three hidden nodes with one hidden layer and SVM with Gaussian kernel function as trained prediction model, and the ANN showed 88.9 % of sensitivity, 96.7 % of specificity, 92.0 % of accuracy and the SVM provided 97.8 % of sensitivity, 95.0 % of specificity, 96.7 % of accuracy. Therefore, SVM was better than ANN for survival prediction.

• The Korean Journal of Pancreas and Biliary Tract
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• v.22 no.4
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• pp.165-171
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• 2017

Background/Aim: There is little data on whether plastic stents with a larger diameter are patent for longer than small stents in patients with bile duct cancer. The aim of this study was to compare the stent survival between 7-French (Fr) and 10-Fr plastic stents and evaluate the factors affecting stent survival. Methods: Patients with biliary obstruction due to biliary tract cancer were enrolled at Yonsei University Wonju College of Medicine from January 2010 to October 2014. Results: A total of 215 patients (7-Fr:10-Fr = 89:126 patients) were retrospectively enrolled. The primary tumor sites were common bile duct (n = 111), hilar (n = 45), and ampulla of Vater (n = 59). Rates of stent migration and stent obstruction were not different between the two groups. The median duration of stent survival was 3.3 months in the 7-Fr group and 5.9 months in the 10-Fr group (p = 0.543). The diameter of the stent did not have an effect on stent survival (hazard ratio 1.11, 95% confidence interval 0.71-1.73, p = 0.649). Conclusions: 7-Fr and 10-Fr stents have similar rates of stent migration and stent obstruction. The stent survival of 7-Fr was not inferior to 10-Fr stents in the management of biliary tract cancer.

• The KIPS Transactions:PartD
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• v.14D no.7
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• pp.829-840
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• 2007

Dirty Data Cleansing technique so far have aimed to integrate large amount of data from various sources and manage data quality resided in DB so that it enables to extract meaningful information. Prompt response to varying environment is required in order to persistently survive in rapidly changing business environment and the age of limitless competition. As system requirement is recently getting complexed, Service Oriented Architecture is proliferated for the purpose of integration and implementation of massive distributed system. Therefore, SOA necessarily needs Data Exchange among services through Data Cleansing Technique. In this paper, we executed quality management of XML data which is transmitted through events between services while they are integrated as a sole system. As a result, we developed Dirty Data Cleansing Service based on SOA as focusing on data cleansing between interactive services rather than cleansing based on detection of data error in DB already integrated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.89-96
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• 2012

Since tactical robots are going to be grown and tactical data communications will be more network-centric, the reliability of wireless tactical data networks is going to be very important in the future. However, the connectivity of such wireless tactical data networks can be extremely uncertain in practical circumstances. In this paper, we propose a searching technique to find out the weak boundary area of the network connectivity using a small UAV(unmanned aerial vehicle) which has a simple polling access function to wireless nodes on the ground in wireless tactical data networks. The UA V calculates the network topology of the wireless tactical data networks and coverts it to the Lapalcian matrix. In the proposed algorithm, we iteratively search the eigenvalues and find a minimum cut in the network resulting in finding the weak boundary of the connectivity for the wireless tactical data networks. If a UAV works as a relay nodes for the weak area, we evaluate that the throughput performance of the proposed algorithm outperforms star connection method and MST(minimum Spanning Tree) connection method. The proposed algorithm can be applied for recovering the connectivity of wireless tactical data networks.

• Review of KIISC
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• v.13 no.1
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• pp.42-55
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• 2003

차세대 광 인터넷 백본망 기술은 WDM(Wavelength Division Multiplexing)기반의 고속 대용량 전광 전달망인 AOTN (All-Optical Transport Network)으로 발전하고 있고, 가입자의 원활한 멀티미디어 서비스의 제공을 위한 망 생존성 보장이 중요한 이슈로 부각되고 있다. 특히 광소자의 고유한 특성을 교묘히 이용하는 물리적 공격은 AOTN의 투명한 데이터 전달 특성으로 인해 기존의 오버헤드를 이용한 관리 시스템이 더 이상 유효하지 않아, 새로운 검출/회복 메커니즘이 요구된다. 본 고에서는 AOTN에서 발생 가능한 공격 유형을 광소자별로 분석하고, 광 레벨에서의 공격 검출과 회복 메커니즘을 소개한다. 이를 바탕으로 공격관리 시스템(Attack Management System: AMS)의 제어 모델을 기술한다.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.279-287
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• 2003

In this paper we propose a local smoothing of the Nelson type estimator for the survival function based on an approximation by the Weibull distribution function. It appears that Mean Square Error and Bias of the smoothed estimator of the Nelson type survival function estimators are significantly smaller than that of the smoothed estimator of the Kaplan-Meier survival function estimator.

• Digital Contents
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• no.4 s.143
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• pp.98-99
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• 2005

급속한 변화와 발전이 예상되는 2005년 한 해의 모바일 산업 전 분야를 조망하는‘제5회 코리아 모바일 그랜드 컨퍼런스’가 3월 10일부터 11일까지 이틀동안 강남역 과학기술회관 국제회의실에서 열렸다. K모바일이 주최한 이번 행사는 정보통신부의 2005년 모바일 관련 사업전략 설명과 SK텔레콤, KTF & LG텔레콤 등 이통3사의 무선데이터 관련 2005년 중점 추진 사업계획 및 방침이 발표됐고 아울러 한계론에 부딪히고 있는 모바일CP의 향후 생존 및 발전전략을 모색해 보는 자리가 마련됐다.

• Journal of the Korean Data and Information Science Society
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• v.17 no.4
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• pp.1067-1076
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• 2006

Although the proportional hazards model is the most common approach used for studying the relationship of event times and covariates, alternative models are needed for occasions when it does not fit data. In the two-sample case, proportional odds models are useful for fitting data whose hazard rates converge asymptotically. In this thesis, we propose a new estimator of the relative odds ratio of the proportional odds model when two independent random samples are observed under uncensorship. We prove the asymptotic normality and consistency of the estimator by using martingale-representation. The efficiency of the proposed is assessed through a simulation study.

• 한국벤처창업학회:학술대회논문집
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• 2016.04a
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• pp.232-234
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• 2016

본 연구의 목적은 사내교육이 직원들의 재직기간에 미치는 영향에 대한 연구로, 실제 사설경비업체의 데이터를 이용하여 생존분석방법으로 퇴직 확률을 추정함으로써 다양한 시사점을 제공해주고 있다. 결론적으로 사내교육에 참여한 직원들이 그렇지 않은 직원들에 비해 퇴직할 확률이 더 낮은 것으로 나타났다. 구체적으로 교육의 종류(직무교육과 마인드교육)에 따라 재직기간에 상이한 영향을 끼치며, 이를 바탕으로 회사는 장기적인 관점에서 적절한 사내교육 프로그램을 개발하여 직원을 교육시킴으로써 우수 인재의 경쟁사로의 이직을 방어할 수 있을 것이다.