• Communications for Statistical Applications and Methods
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• 제18권2호
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• pp.201-211
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• 2011

In many cases, populations in the real world are composed of different subpopulations. Furthermore, in addition to the heterogeneity in the lifetimes of items, there also could be the heterogeneity in the efficiency or performance of items. In this case, the reliability measures should be defined in a different way. In this article, we consider the mixture of stochastically ordered subpopulations. Efficiency based reliability measures are defined when the performance of items in the subpopulations has different levels. Discrete and continuous mixing models are studied. The concept of the association between the lifetime and the performance of items in subpopulations is defined. It is shown that the consideration of efficiency can change the shape of the mixture failure rate dramatically especially when the lifetime and the performance of items in subpopulations are negatively associated. Furthermore, the modelling method proposed in this paper is applied to the case when the stress levels of the operating environment of items are different.

• 응용통계연구
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• 제29권6호
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• pp.1117-1128
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• 2016

고차원 유전체 자료를 사용하는 유전체 연관 분석에서는 벌점 우도함수 기반의 회귀계수 규제화 방법이 질병 및 표현형질에 영향을 주는 유전자를 발견하는데 많이 이용된다. 특히, 네트워크 기반의 규제화 방법은 유전체 연관성 연구에서의 유전체 경로나 신호 전달 경로와 같은 생물학적 네트워크 정보를 사용할 수 있으므로, Lasso나 Elastic-net과 같은 다른 규제화 방법들과 비교했을 경우 네트워크 기반의 규제화 방법이 보다 더 정확하게 관련 유전자들을 찾아낼 수 있다는 장점을 가지고 있다. 그러나 네트워크 기반의 규제화 방법은 그룹 구조를 갖고 있는 고차원 유전체 자료에는 적용시킬 수 없다는 문제점을 가지고 있다. 실제 SNP 데이터와 DNA 메틸화 데이터처럼 대다수의 고차원 유전체 자료는 그룹 구조를 가지고 있으므로 본 논문에서는 이러한 그룹 구조를 가지고 있는 고차원 유전체 자료를 분석하고자 네트워크 기반의 규제화 방법에 주성분 분석(principal component analysis; PCA)과 부분 최소 자승법(partial least square; PLS)과 같은 차원 축소 방법을 결합시키는 새로운 분석 방법을 제안하고자 한다. 새롭게 제안한 분석 방법은 몇 가지의 모의실험을 통해 변수 선택의 우수성을 입증하였으며, 또한 152명의 정상인들과 123명의 난소암 환자들로 구성된 고차원 DNA 메틸화 자료 분석에도 사용하였다. DNA 메틸화 자료는 대략 20,000여개의 CpG sites가 12,770개의 유전자에 포함되어 있는 그룹 구조를 가지고 있으며 Illumina Innium uman Methylation27 BeadChip으로부터 생성되었다. 분석 결과 우리는 실제로 암에 연관된 몇 가지의 유전자를 발견할 수 있었다.

• Communications for Statistical Applications and Methods
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• 제19권4호
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• pp.517-526
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• 2012

In this paper a support vector method is proposed for use when the sample observations are contaminated by a normally distributed measurement error. The performance of deconvolution density estimators based on the support vector method is explored and compared with kernel density estimators by means of a simulation study. An interesting result was that for the estimation of kurtotic density, the support vector deconvolution estimator with a Gaussian kernel showed a better performance than the classical deconvolution kernel estimator.

• 항공산업연구
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• 통권66호
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• pp.45-56
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• 2003

Airlines service is very important so as to overcome the rapid environmental changes of the air transportation market at home and abroad. Author investigates the impact of Determinants on the performance of airlines in all the world. Three variables of performance measurement were used : revenue, net profit, and passengers. Data analyses were based on service ranking, financial and passenger information of the world's top 50 Airlines collected from Business Traveller, World Air Transport Statistics and Airline Business. The findings of this study could be summarized as follows : Service ranking was not related to the airlines performances such as revenue, net profit, passengers and so fourth. But airlines size(employees, fleet size) was related to the airlines performances such as passengers and revenue passenger.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.5878-5904
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• 2017

This paper proposes a novel intelligent wheelchair vehicle system that enables upper limb exercises, lower limb standing exercises and rehabilitation training in a daily life. The proposed system, which can be used to prevent at least the degeneration of body movements and further atrophy of musculoskeletal system functions, considers the characteristics and mobility of the old and the disabled. Its main purpose is to help the old and the disabled perform their daily activities as much as they can, minimizing the extent of secondary disabilities. In other words, the system will provide the old and the disabled with regular and quantitative rehabilitation exercises and diagnosis using the wheelchair-based upper/lower limb rehabilitation vehicle system and then verify their effectiveness. The system comprises an electric wheelchair, a biometric module to identify individual characteristics, and an upper/lower limb rehabilitation vehicle. In this paper the design and configuration of the developed vehicle is described, and its operation method is presented. Moreover, to verify the tracking performance of the proposed system, dangerous situations according to biosignal changes occurring during the rehabilitation exercise of a non-disabled examinee are analyzed and the performance of the upper/lower limb rehabilitation exercise function depending on muscle strength is evaluated through a neural network algorithm.

• 인터넷정보학회논문지
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• 제22권5호
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• pp.1-8
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• 2021

Small-cells in heterogeneous networks are one of the important technologies to increase the coverage and capacity in 5G cellular networks. However, due to the randomly arranged small-cells, co-tier and cross-tier interference increase, deteriorating the system performance of the network. In order to manage the interference, some channel management methods use fractional frequency reuse(FFR) that divides the cell coverage into the inner region(IR) and outer region(OR) based on the distance from the macro base station(MBS). However, since it is impossible to properly measure the distance in the method with FFR, we propose a new interference aware FFR(IA-FFR) method to enhance the system performance. That is, the proposed IA-FFR method divides the MUEs and SBSs into the IR and OR groups based on the signal to interference plus noise ratio(SINR) of macro user equipments(MUEs) and received signals strength of small-cell base stations(SBSs) from the MBS, respectively, and then dynamically assigns subchannels to MUEs and small-cell user equipments. As a result, the proposed IA-FFR method outperforms other methods in terms of the system capacity and outage probability.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.485-494
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• 2021

본 연구는 수술실 신규간호사의 웹 기반 동영상 프로그램 선택속성이 학습 몰입을 매개로 차후 간호 수행능력에 관한 확신에 미치는 영향을 검증하는 것이 목적이다. 연구대상은 인천 및 경기도 소재 대학병원의 수술실 근무 중인 간호사를 대상으로 하였으며, 250개의 표본을 분석에 활용하였다. 연구방법은 구조화된 설문지를 사용하여 2019년 7월부터 8월까지 수집되었다. 참가자들은 인천과 경기에 있는 대학병원 수술실 250명의 간호사이다. 수집 된 데이터는 IBM SPSS Statistics 25.0과 AMOS 24.0을 사용하여 분석하였으며, 구조모형을 통해 위에 적합도 지표를 기반으로 직접효과와 간접효과를 측정하였다. 연구 결과, 수술실 신규간호사는 수술과 1차적으로 직결되는 위생 안전요인과 환자 관리요인을 상대적으로 더욱 중요하게 인지하였다. 학습 몰입을 통하여 차후 간호 수행능력에 관한 확신이 있었고, 위생 안전요인의 경우 학습 몰입이 없어도 수술실 신규간호사가 중요성을 인지하여 차후 간호 수행능력에 관한 확신에 긍정적 영향이 미침을 검증하였다. 따라서 향후 시각적 효과에 더 비중을 둔 웹 기반 동영상 프로그램 구성을 통해 간호의 위생 안전요인뿐만 아니라 환자 관리요인 그리고 간호 관련 요인 모두가 환자의 생명과 회복에 핵심적 단계임을 신규간호사에게 적합하게 이해시킬 필요가 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1348-1375
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• 2018

Support Vector Machine (SVM) is a well-known machine learning classification algorithm, which has been widely applied to many data mining problems, with good accuracy. However, SVM classification speed decreases with increase in dataset size. Some applications, like video surveillance and intrusion detection, requires a classifier to be trained very quickly, and on large datasets. Hence, this paper introduces two filter-based instance selection techniques for optimizing SVM training speed. Fast classification is often achieved at the expense of classification accuracy, and some applications, such as phishing and spam email classifiers, are very sensitive to slight drop in classification accuracy. Hence, this paper also introduces two wrapper-based instance selection techniques for improving SVM predictive accuracy and training speed. The wrapper and filter based techniques are inspired by Cuckoo Search Algorithm and Bat Algorithm. The proposed techniques are validated on three popular e-fraud types: credit card fraud, spam email and phishing email. In addition, the proposed techniques are validated on 20 other datasets provided by UCI data repository. Moreover, statistical analysis is performed and experimental results reveals that the filter-based and wrapper-based techniques significantly improved SVM classification speed. Also, results reveal that the wrapper-based techniques improved SVM predictive accuracy in most cases.

• 한국간호교육학회지
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• 제30권2호
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• pp.170-181
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• 2024

Purpose: This study aims to assess the importance and performance of patient safety activities for inpatients in small- and medium-sized hospitals. The objective is to identify the need for patient safety education by analyzing differences in importance and performance ratings. Methods: The study involved 300 patients hospitalized in three small- and medium-sized hospitals. Data collection took place in October 2023, focusing on investigating the importance and performance of patient safety activities. Descriptive statistics and an Importance-Performance Analysis (IPA) were conducted using the IBM SPSS statistics 25.0 program. Results: The average importance of patient safety activities was 3.51±0.41, and the average performance was 3.37±0.43, indicating that the importance of patient safety activities was higher than their performance. According to the IPA, the components of patient safety activities that fell into the second quadrant of high importance but low performance included three medication-related items and one test/procedure/surgery-related item. Conclusion: In this study, it was found that inpatients in small- and medium-sized hospitals had a higher importance on patient safety activities than performance and needed ways to increase their performance. Therefore, it is necessary to develop a customized educational program that can increase the practical performance of inpatients' patient safety activities based on the contents that were determined to need improvement.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 가을 학술발표논문집 Vol.32 No.2 (1)
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• pp.241-243
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• 2005

Web services (WS) present a new promising software technology, which provides application-to-application interaction. They are built on the top of existing web protocol and based on open XML standards. Web services are described using WSDL, and the UDDI is a integration directory provide registry of Web Services descriptions. WSDL provides information of Web Services but it is getting more and more important to know more than those provided by WSDL. From WSDL we can not get the information like usage of WS, performance of WS, complexity of WS, usability of WS with other web service. In this paper, we proposed a new method for Web Services so called Public Web Services Analyzer (PWSA). This technique is based on analyzing various public UDDI registries in order to get various kinds of statistics of web services. Those statistics will be used by both web services developers and consumers for finding them suitable services for their needs. PWSA guarantees that it can provide enough information to find right web services for both Web Services Consumers and Web Service Developers.