• 품질경영학회지
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• 제25권3호
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• pp.74-85
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• 1997

In this paper we calculate the subgroup size necessary for detecting the change of percent defective with several detection probabilities for orginal population fraction nonconforming p, changed population fraction nonconforming $p^*$, and the ratio k=$p^*$/p in the usage of p control charts. From our calculation we can know the error level of normal a, pp.oximation in detection probability calculation and recommend the subgroup size with lower error levels of normal a, pp.oximation, and then we show the reasonable subgroup size necessary for p, $p^*$, k, and the detection probability of the change of fraction nonconforming in a process. The information that we here show in tables will be useful when p control chart users decide the subgroup size in the p control chart users decide the subgroup size in the p control chart.

• 지질공학
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• 제17권2호
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• pp.197-204
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• 2007

터널은 굴착에 의해 지반의 변형을 일으키며, 지보를 설치하고 시간이 지남에 따라 점차 안정화된다. 터널 굴착이 지반 거동에 미치는 영향은 계측지점과 막장간의 거리가 증가함에 따라 감소한다. 터널의 변위가 수렴하여 안정화되는 시점을 예측할 수 있다면, 안정화 이후 이루어지는 여러 공정들을 앞당김으로써 시간적, 경제적 손실을 줄일 수 있다. 따라서 본 연구에서는 변위 수렴 시점을 예측하기 위하여 관리도 기법을 적용하였다. 퇴적암을 기반으로 하는 터널에 대한 관리도 판정 결과, 막장에서부터의 거리가 최대 100 m 이내에서 변위가 수렴하였다.

• 품질경영학회지
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• 제35권2호
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• pp.37-44
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• 2007

Today, the statistical process control (SPC) in manufacture environment is an important role at the process by the productivity improvement of the manufacturing systems. The control chart in this statistical method is widely used as an important statistical tool to find the assignable cause that provoke the change of the process parameters such as the mean of interest or standard deviation. But the traditional SPC don't grasp the change of process according to the points fallen the near control limits because of monitoring the variance of process such as the fixed sampling interval and the sample size and handle the cost of the aspect of these sample point. The control chart can be divided into the statistical and economic design. Generally, the economic design considers the cost that maintains the quality level of process. But it is necessary to consider the cost of the process improvement by the learning effects. This study does the economic design in the VSI $\bar X$ control chart and added the concept of loss function of Taguchi in the cost model. Also, we preyed that the VSI $\bar X$ control chart is better than the FSI $\bar X$ in terms of the economic aspects and proposed the standard of the process improvement using the VSI $\bar X$ control chart.

• 한국안광학회지
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• 제15권3호
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• pp.241-245
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• 2010

목적: 시각적 공간감각인 물체의 거리감과 움직임에 대하여 시력측정이 가능한 격자시표를 제안하고자 한다. 방법: 주기성을 갖는 한 쌍의 격자를 제작하여 이를 렌즈로 결상하고 그 상을 시력표에 투영하여 도형모양의 시표를 형성한다. 이 격자를 회전 또는 선형 이동하여 도형모양의 시표에 거리감과 움직임을 주는 형식으로 피검사자가 공간감각을 인지할 때 격자의 위치변위를 알 수 있도록 한다. 결과: 격자를 회전하여 거리감의 정도를 나타내는 측정값은 이론식에 의한 값과 비교하여 평균 2.98%의 오차를 나타냈고 선형이동에 따른 움직임을 인식하는 결과는 격자가 $\theta=15^{\circ}$ 회전된 상태에서 평균 1.73%의 오차를 나타냈다. 결론: 본 실험에서 제시한 무아레 무늬의 시표는 시각적 공간감각에서 피검사자의 거리감과 물체의 움직임을 측정하는 시표로서 그 활용이 가능하다.

• 한국안광학회지
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• 제17권1호
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• pp.53-58
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• 2012

목적: 최적구면굴절상태에서 진용한 시력표로 측정한 logMAR 시력에 의한 난시예상량을 파악해 보고, 투영식 소수시력표와 비교해 보고자 하였다. 방법: 대학생 150명 300안을 대상으로 logMAR 시력과 소수시력을 측정하여 완전교정 때의 난시량과 비교하였다. 결과: 진용한 시력표가 투영식 시력표에 비해 시표 줄 간의 차이가 0.25 D이상으로 비교적 구별이 뚜렷하였다. 또한 난시량과의 상관성은 logMAR 시력이 r = 0.8578로 소수시력 r = -0.7199 보다 높았다. 결론: 최적구면굴절상태에서 logMAR 시력을 통하여 난시량을 예측할 수 있었고, 투영식 시력표 보다 진용한 시력표가 단계별 난시예상량을 예측하는 것이 쉬운 것으로 판단된다.

• 한국안광학회지
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• 제18권3호
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• pp.291-295
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• 2013

Purpose: The purpose of this study was to investigate the effect of under and over refractive correction on visual acuity performance and the variation of the visual performance measurement using two different visual acuity charts. Methods: Ten young adults, aged between 19 and 25 years old, were recruited. Inclusion criteria: no history of ocular injury or pathology with a best-corrected visual acuity of 6/6 on dominant eye. The over and under refractive corrections were induced using minus and plus spherical ophthalmic lenses in 0.50 D steps up to 3.00 D; as well as using three axis orientations of cylindrical ophthalmic lenses ($45^{\circ}$, $90^{\circ}$ and $180^{\circ}$) in 0.50 D steps. The variation of visual acuity performance measurements was investigated using Bailey-Lovie LogMAR chart and Landolt C chart. Results: The visual acuity changes with lenses were significantly different between two charts [F = 49.15, p < 0.05 with plus spherical ophthalmic lenses and F = 174.38, p < 0.05 with minus spherical ophthalmic lenses]. The visual acuity changes with three different cylindrical axis showed no significant difference between Bailey-Lovie LogMAR chart [F = 2.35, p > 0.05] and Landolt C chart [F = 3.12, p = 0.05]. Conclusions: The over and under refractive correction affected the visual acuity performance differently. The Landolt C chart and Bailey-Lovie LogMAR chart demonstrated variation in measurements.

• Journal of the Korean Data and Information Science Society
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• 제27권2호
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• pp.523-530
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• 2016

Most classical control charts assume that processes are serially independent, and autocorrelation among variables makes them unreliable. To address this issue, a variety of statistical approaches has been employed to estimate the serial structure of the process. In this paper, we propose a multioutput least squares support vector regression and apply it to construct a residual multivariate cumulative sum control chart for detecting changes in the process mean vector. Numerical studies demonstrate that the proposed multioutput least squares support vector regression based control chart provides more satisfying results in detecting small shifts in the process mean vector.

• 품질경영학회지
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• 제43권4호
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• pp.521-532
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• 2015

Purpose: The purpose of this study is to compare two multivariate cumulative sum (MCUSUM) charts designed for spatio-temporal surveillance in terms of not only temporal detection performance but also spatial detection performance. Method: Experiments under various configurations are designed and performed to test two CUSUM charts, namely SMCUSUM and RMCUSUM. In addition to average run length(ARL), two measures of spatial identification accuracy are reported and compared. Results: The RMCUSUM chart provides higher level of spatial identification accuracy while two charts show comparable performance in terms of ARL. Conclusion: The RMCUSUM chart has more flexibility, robustness, and spatial identification accuracy when compared to those of the SMCUSUM chart. We recommend to use the RMCUSUM chart if control limit calibration is not an urgent task.

• 산업경영시스템학회지
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• 제21권47호
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• pp.211-218
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• 1998

In start-up process control applications it may be necessary to limit the sample size to one measurement. A control chart for individual measurements is used whenever it is desirable to examine each individual value from the process immediately. A possible option would be to use an exponential weighted moving(EWM), using modifying statistics with individual measurement, chart for monitoring the process center, and using a moving range (MR) chart for monitoring process variability. In this paper it is shown that there is scheme in using the EWM procedure based on average run length. An expression for the ARL is given in terms of an integral equation, approximated using numerical quadrature. In this case, where it is reasonable to assume normality and negligible autocorrelation in the observations, provide graphs that simplify the design of EWM-MR chart and taking method of exponential smoothing constant(λ) and constant(K) are suggested. The charts suggested above evaluate using the conditional probability.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2012년도 춘계학술발표대회논문집
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• pp.455-456
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• 2012

본 논문에서는 센서네트워크 연구단계에서 손쉽게 사용할 수 있는 센서데이터 모니터링 프로그램을 Java기반의 차트디자인 도구 JFreeChart를 이용하여 설계하고 구현한다.