• 한국과학교육학회지
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• 제25권7호
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• pp.787-793
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• 2005

이 연구의 목적은 초등학생의 인지수준에 따른 확률적 사고의 형성 정도와 TS 프로그램의 확률 활동이 확률적 사고의 형성에 미치는 효과를 알아보는 것이었다. 이를 위하여 초등학교 6학년 152명을 실험집단과 통제집단으로 나누어, 실험집단에는 TS 프로그램의 확률 활동을 투입하였고, 통제집단에는 정규 교육과정을 운영하였다. 투입 전에 SRT II와 확률적 사고 검사를 실시하여 학생들의 인지수준에 따른 확률적 사고의 형성 정도를 조사하였고, 투입 후에 확률적사고 검사를 실시하여 처치의 효과를 알아보았다. 연구 결과에 의하면, 확률 문제 해결에서 구체적 조작기와 과도기 학생들은 주관적 전략과 양적 전략을 혼용하여 사용하였으며, 전기 형식적 조작기 학생들은 양적 전략을 많이 사용하여 인지수준이 높을수록 보다 높은 수준의 확률적 사고를 하고 있었다. TS 프로그램의 확률 활동은 학생들의 확률적 사고 형성에 효과적이었다. 확률적 사고의 형성을 인지수준에 따라 분석한 결과, 전기 구체적 조작기와 과도기 학생들에게 효과적이었음을 알 수 있었다.

• 한국안전학회지
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• 제32권6호
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• pp.1-8
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• 2017

P-PIE is a program developed to estimate failure probability of pipes and pressure vessels considering fatigue and stress corrosion crack growth. Using the program, crack growth simulation was performed with an initially existing crack in order to examine the effects of initial crack depth distribution on the leak probability of pipes. In the simulation stress corrosion crack growth was considered and several crack depth distribution models were used. From the results it was found that the initial crack depth distribution gives great effect on the leak probability of pipes. The log-normal distribution proposed by Khaleel and Simonen gives lower leak probability compared other exponential distribution models. The effects of the number and the quality of pre-service and in-service inspections on the leak probability were also examined and it was recognized that the number and the quality of pre-service and in-service inspections are also give great effect on the leak probability. In order to reduce the leak probability of pipes in plants it is very important to improve the quality of inspections. When in-service inspection is performed every 10 years and the quality of inspection is above the very good level, the leak probability shows nearly constant value after the first inspection for an initially existing crack.

• 품질경영학회지
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• 제34권1호
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• pp.27-33
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• 2006

In this paper, an effective method for identifying influential main effects and interactions in the 2-level factorial designs is suggested by exploiting the resolution V designs developed by Kim(1992). For analysis of such designs, we employ the Bayesian approach for easy and clear identification of influential effects in the half normal probability plot.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제14권1호
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• pp.69-79
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• 2011

본 연구의 목적은 확률을 학습하지 않은 3, 4, 5학년 학생들의 확률 개념에 대한 이해 수준을 살펴보고, 확률 학습에 대한 가능성을 탐색하는 것이다. 이를 위해 3, 4, 5학년 학생을 대상으로 지필검사를 통한 조사 연구를 실시하였고, 선행연구를 토대로 한 확률 이해 분석의 틀을 분석기준으로 삼았다. 본 연구의 결과 학생들의 확률 개념 평균 이해 수준은 표본공간에서 가장 높게 나타났고 사건의 확률, 공평성, 확률 비교 순이었으며, 특히 표본공간에 대해 가장 높은 수준을 나타냈고 이러한 결과는 3, 4, 5학년의 공통적인 현상이었다. 반면 학생들의 독립성에 대한 이해 수준은 낮은 편이었고 학년 간에 유의한 수준 차이가 없었으며, 조건부 확률에 대한 이해는 가장 낮았다.

• 한국정보통신학회논문지
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• 제17권11호
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• pp.2563-2568
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• 2013

최근 옥외용 이동통신시스템과 동일 주파수를 사용하면서 추가적으로 용량을 확보할 수 있는 옥내용 모바일 통신 시스템을 위한 초소형 기지국에 대한 연구 및 개발이 활발히 진행되고 있다. 본 연구에서는 옥내용 모바일 통신 시스템에서 초소형 기지국의 특성을 고려한 시스템 레벨 시뮬레이터를 개발하였고 초소형 기지국 환경에서 혼잡한(Congested) 기지국의 아웃티지 확률(Outage Probability)을 줄이는 적응적 Load-Balancing 방안을 제안하였다. 본 시뮬레이터에서는 초소형 기지국 특성을 고려한 링크 레벨 시뮬레이션 결과를 반영하였으며, 본 시뮬레이터를 이용하여 옥내용 모바일 통신 시스템에서 Load-Balancing 방안을 적용하였을 때와 적용하지 않았을 때의 아웃티지 확률을 비교해 보았다. 제안한 Load-Balancing 방안의 사용을 통해 혼잡한 기지국의 아웃티지 확률을 줄이고 전체 시스템의 성능을 향상시킬 수 있음을 보였다.

• Journal of Gastric Cancer
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• 제15권4호
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• pp.262-269
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• 2015

Purpose: Intraabdominal abscess is one of the most common reasons for re-hospitalization after gastrectomy. This study aimed to develop a model for estimating the probability of intraabdominal abscesses that can be used during the postoperative period. Materials and Methods: We retrospectively reviewed the clinicopathological data of 1,564 patients who underwent gastrectomy for gastric cancer between 2010 and 2012. Twenty-six related markers were analyzed, and multivariate logistic regression analysis was used to develop the probability estimation model for intraabdominal abscess. Internal validation using a bootstrap approach was employed to correct for bias, and the model was then validated using an independent dataset comprising of patients who underwent gastrectomy between January 2008 and March 2010. Discrimination and calibration abilities were checked in both datasets. Results: The incidence of intraabdominal abscess in the development set was 7.80% (122/1,564). The surgical approach, operating time, pathologic N classification, body temperature, white blood cell count, C-reactive protein level, glucose level, and change in the hemoglobin level were significant predictors of intraabdominal abscess in the multivariate analysis. The probability estimation model that was developed on the basis of these results showed good discrimination and calibration abilities (concordance index=0.828, Hosmer-Lemeshow chi-statistic P=0.274). Finally, we combined both datasets to produce a nomogram that estimates the probability of intraabdominal abscess. Conclusions: This nomogram can be useful for identifying patients at a high risk of intraabdominal abscess. Patients at a high risk may benefit from further evaluation or treatment before discharge.

• Communications for Statistical Applications and Methods
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• 제7권2호
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• pp.499-511
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• 2000

We consider a stable tandem network which consists of two M/M/1 nodes and study the probability that the total backlog exceeds a large level N. Since the excessive backlog is a rare event, it is difficult to estimate this probability efficiently by using the crude Monte Carlo simulation. Instead we perform the ;$h$-transform proposed by McDonald(1999) to obtain the twisted network, in which the node with the larger load is overloaded. Then we use it to run the fast simulation.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2012년 춘계학술대회
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• pp.75-80
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• 2012

The research presents a guideline for quality practitioners to provide a full comprehension of differences in theoretical and practical interpretations of assumed sampling errors of and significance probability of calculated p-value. Besides, the study recommends the use of statistical inferences methods with known parameters to identify the improvement effects. In practice, the quality practitioners obtain the known parameters through systematic quality Database (DB) activities.

• Journal of Communications and Networks
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• 제15권1호
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• pp.15-24
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• 2013

Provisioning of quality of service (QoS) is a key issue in any multi-media system. However, in wireless systems, supporting QoS requirements of different traffic types is a more challenging problem due to the need to simultaneously minimize two performance metrics - the probability of dropping a handover call and the probability of blocking a new call. Since QoS requirements are not as stringent for non-real-time traffic, as opposed to real-time traffic, more calls can be accommodated by releasing some bandwidth from the already admitted non-real-time traffic calls. If the released bandwidth that is used to handle handover calls is larger than the released bandwidth that is used for new calls, then the resulting probability of dropping a handover call is smaller than the probability of blocking a new call. In this paper, we propose an efficient call admission control algorithm that relies on adaptive multi-level bandwidth-allocation scheme for non-realtime calls. The scheme allows reduction of the call dropping probability, along with an increase in the bandwidth utilization. The numerical results show that the proposed scheme is capable of attaining negligible handover call dropping probability without sacrificing bandwidth utilization.

• 한국통신학회논문지
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• 제30권9B호
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• pp.596-601
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• 2005

In this paper it is focused on the relation between CLR(Cell Loss Ratio) and blocking probability in the wireless ATM access transport. Traffic model of wireless ATH access transport is based on the cell scale, burst scale and call connection level. The CLR due to buffer overflow for wireless access node is derived for VBR traffic. The CLR due to transmission errors for wireless channel is derived. Using the CLR for both access node and wireless channel: the CLR of wireless ATM access transport is derived. The relation between CLR and blocking probability is analyzed for VBR traffic to evaluate performance of wireless ATM access transport.