• Communications for Statistical Applications and Methods
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• 제14권1호
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• pp.155-167
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• 2007

Knowing the time of the process change could lead to quicker identification of the responsible special cause and less process down time, and it could help to reduce the probability of incorrectly identifying the special cause. In this paper, we propose the maximum likelihood estimator (MLE) for the process change point when a control chart is used in monitoring the mean of a process in which the observations can be modeled as an AR(1) process plus an additional random error. The performance of the proposed MLE is compared to the performance of the built-in estimator when they are used in EWMA charts based on the residuals. The results show that the proposed MLE provides good performance in terms of both accuracy and precision of the estimator.

• Communications for Statistical Applications and Methods
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• 제10권3호
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• pp.825-833
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• 2003

Knowing the time of the process change could lead to quicker identification of the responsible special cause and less process down time, and it could help to reduce the probability of incorrectly identifying the special cause. In this paper, we propose a maximum likelihood estimator of the process change point when a Shewhart $\bar{X}$ chart with variable sample size (VSS) scheme signals a change in the process mean. Also we build a confidence interval for the process change point by using the likelihood function.

• 디지털융복합연구
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• 제9권6호
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• pp.13-25
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• 2011

본 연구는 전문계 고등학교의 취업률 제고를 위한 특성을 파악하는데 목적을 두고 있다. 이러한 수단으로 등장한 특성화 개념을 고찰하고 운영 실태를 분석하여 특성화 고등학교로의 전환에 필요한 개선점을 제시하고자 하였다. 전문계고 위기의 주된 원인 요인들은 매우 다양하며 이러한 요인들이 전문계 고등학교의 취업률제고에 부정적 영향을 미칠 것으로 판단된다. 또한 이들 요인들의 부정적 영향을 최소화하는 다양한 개선방안을 제시하였다. 따라서 본 논문에서는 이들 전문계 고등학교의 문제점과 개선방안을 파악하여 정책적 방안을 제시하고자 탐색적 연구를 하였다.

• 전기학회논문지P
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• 제64권2호
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• pp.74-78
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• 2015

With the improvement of living standards and economic development, electricity consumption continues to grow. The electricity is a special energy which is hard to store, so its supply must be consistent with the demand. The objective of electricity demand forecasting is to make best use of electricity energy and provide balance between supply and demand. Hence, it is very important work to forecast electricity demand with higher precision. So, various forecasting methods have been developed. They can be divided into five broad categories such as time series models, regression based model, artificial intelligence techniques and fuzzy logic method without considering special-day effects. Electricity demand patterns on holidays can be often idiosyncratic and cause significant forecasting errors. Such effects are known as special-day effects and are recognized as an important issue in determining electricity demand data. In this research, we developed the power demand forecasting method using ELM(Extreme Learning Machine) for special day, particularly, lunar new year and Chuseok holiday.

• 대한안전경영과학회지
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• 제24권1호
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• pp.91-98
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• 2022

Since cranes are a kind of complex human-machine systems, it is almost impossible to completely secure safety with current technologies. Therefore, managerial interventions to prevent human errors are needed for safely operating a crane. The Occupational Safety and Health law states that cabin-type crane operators should have crane drivers' licence and crane-related operators (e.g., pendent-type crane operators, slinging workers) should take a special safety training. However, statistics on industrial accidents showed that fatalities due to crane accidents (185 accidents occurred during 2013~2017) were the highest among hazardous machinery and equipment. To effectively control the crane-related accidents, voices of crane workers need to be analyzed to investigate the current status. This study surveyed perceived causes of crane accidents and status of special safety training for crane workers of 387. The survey revealed that 24.3% of the respondents experienced crane accidents and 31.4% eye-witnessed crane accidents. 79% of the respondents pointed human errors such as improper crane operation and improper slinging as the first cause. Lastly, only 16.7% of the respondents took a professional special safety training; but the rest took lecture-based or incomplete education. The findings of the present study can be applied to improve crane-related policies and special safety training systems.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2004년도 학술발표논문집
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• pp.179-184
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• 2004

Statistical process control (SPC) and engineering process control (EPC) are based on different strategies for process quality improvement. SPC reduces process variability by detecting and eliminating special causes of process variation, while EPC reduces process variability by adjusting compensatory variables to keep the quality variable close to target. Recently there has been need for an integrated process control (IPC) procedure which combines the two strategies. This article considers a scheme that simultaneously applies SPC and EPC techniques to reduce the variation of a process. The process disturbance model under consideration is an IMA(1,1) model with a location shift. The EPC part of the scheme adjusts the process, while the SPC part of the scheme detects the occurrence of a special cause. For adjusting the process repeated adjustment is applied by compensating the predicted deviation from target. For detecting special causes the two kinds of exponentially weighted moving average (EWMA) control chart are applied to the observed deviations: One for detecting location shift and the other for detecting increment of variability. It was assumed that the adjustment of the process under the presence of a special cause may change any of the process parameters as well as the system gain. The effectiveness of the IPC scheme is evaluated in the context of the average cost per unit time (ACU) during the operation of the scheme. One major objective of this article is to investigate the effects of the process parameters to the ACU. Another major objective is to give a practical guide for the efficient selection of the parameters of the two EWMA control charts.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.64-67
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• 2000

It is usual that the medical examination of human body need special knowledpe and equipments. Thus we have to spend Lime and energy on going to special place such as hospital where doctors and equipments are. Which often cause missing a good chance af medical treatment as well as giving us inconvenience. However many simple and convenient equipments were developed for checking our health conditions recently. O-ring test is accepted a3 one of useful methods to examine our heallb conditions. Also the test is recognized as a uscful means to judge, withoul any special equipment and medical knowledge, if some medical substances or foods are beneficial or harmful to our health. However, the judgement may be mcorrect because it depend on doctor's subjective point of view.In this study, we developed an automatic O-ring t a r mach~ne which enable us to check our health conditions objectively and quantitatively. The validity of the idea to develope the machine was proved by experiments.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.236-241
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• 2008

경찰공무원은 공직의 체계상 특정직으로 분류된다. 대부분의 특정직은 별도의 인사법규에 근거하여 개별적 인사행정이 이루어지고 있다. 조직과 임무가 특수한 만큼 일반직에 대한 인사행정을 적용햐는데 한계가 있기 때문이다. 경찰 근무성적평정도 이러한 논리로 타 공직과는 상이한 형태로 실시되고 있다. 본 연구에서는 경찰 근무성적평정 제도의 보다 바람직한 운영을 도모하기 위해서 평정결과에 대한 검증절차를 도입할 것을 제안하였다. 다만, 제도시행 초기에는 검증대상을 최종 평정권자의 결과만으로 한정하는 것이 바람직할 것이다.

• Journal of the Korean Data and Information Science Society
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• 제20권2호
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• pp.435-443
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• 2009

생산 공정에서 관리도를 통하여 이상원인을 탐지하는 경우 이상상태의 신호가 발생하면 교정활동을 통하여 이를 규명하고 제거한 후 다시 공정을 가동시키는 것이 일반적이다. 이때 이상원인이 발생한 시점인 공정의 변화시점을 알 수 있다면 보다 빠르고 정확하게 이상원인을 규명하고 이를 제거할 수 있을 것이다. 이 논문에서는 누적이동평균(1,1) 모형, 즉 IMA(1,1) 모형을 따르는 공정에서 관리도를 사용하여 모수들의 변화를 탐지하는 경우 공정의 변화시점에 대한 MLE를 제안하고, 제안된 추정량의 효율에 대하여 연구하였다.

• 융합정보논문지
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• 제11권7호
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• pp.181-188
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• 2021

본 연구는 중소병원들이 지속적으로 안정성과 효과성을 유지할 수 있는 전략방안의 검토를 위하여 전문병원에 대한 기대수준 대비 이용 후 지각 만족도와 기대요소 간의 관계를 살펴보았다. 연구방법은 20세 이상의 부산 및 경남 거주자를 대상으로 구조화된 설문지를 이용하여, 카이제곱 검정, 로지스틱 회귀분석을 실시하였다. 연구결과, 첫째, 응답자의 68.0%가 특성화를 표방하는 병원을 전문병원으로 인식하였고, 보건복지부 지정병원이라 인식한 응답자는 21.3%로 확인되었다. 둘째, 주관적으로 인식하는 전문병원 이용 경험이 있는 경우에는 대부분의 이용자들이 기대수준 대비 지각하는 만족도가 충족되었으며, 이용했던 병원을 계속 이용 할 의사가 있는 것으로 확인되었다. 셋째, 기대수준 대비 이용 후 지각 만족도에는 치료에 대한 안전성과 치료의 질적 수준이 유의하게 영향을 미치는 인과관계가 있음을 확인하였다. 이 결과는 의료소비자들의 지각 만족도 향상과 감정적 애착 관리를 통한 장기적이고 지속적인 효과를 위한 전략 수립에 유용한 정보로 활용될 수 있을 것으로 사료된다.