• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.707-712
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• 2015

During the welding process, welding distortion is caused by the non-uniformity of the temperature distribution in the weldment. Welding distortion is redistributed because the residual stress and rigidity change according to the removal of the welded structure. In shipbuilding in particular, this phenomenon may be observed during the cutting process of lugs that are attached to blocks for transfer. The redistribution of welding distortion also causes problems, such as damage to the cutting tool. The aim of this study is to experimentally analyze the redistribution of welding distortion because of the partial removal of the welded structure. In the experiments conducted in this study, fillet welding and cutting were performed, and longitudinal bending and angular distortion in the welded structures were then investigated and analyzed.

• The Korean Journal of Applied Statistics
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• v.22 no.1
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• pp.29-39
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• 2009

Among others, ROC and CAP curves are used to explore the discriminatory power between the defaults and non-defaults, based on the distribution of the probability of default in credit rating works. ROC and CAP curves are plotted in terms of various ratios of the probability of default. Each point on ROC and CAP curves is calculated according to cutting points (scores) for classifying between defaults and non-defaults. In this paper, adjusted ROC and CAP curves are proposed by using functions of ratios of the probability of default. It is possible to recognize the score corresponding to a point oil these adjusted curves, and we can identify the best score to show the optimal discriminatory power. Moreover, we discuss the relationships between the best score obtained from the adjusted ROC and CAP curves and the score corresponding to Kolmogorov - Smirnov statistic to test the homogeneous distribution functions of the defaults and non-defaults.

• The Korean Journal of Applied Statistics
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• v.34 no.5
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• pp.735-744
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• 2021

Maintaining the lifetime of a product is one of the objectives of quality control. In real processes, most samples are constructed with censored data because, in many situations, we cannot measure the lifetime of all samples due to time or cost problems. In this paper, we propose two cumulative sum (CUSUM) control charting procedures to monitor the mean of type I right-censored lognormal lifetime data. One of them is based on the likelihood ratio, and the other is based on the binomial distribution. Through simulations, we evaluate the performance of the two proposed procedures by comparing the average run length (ARL). The overall performance of the likelihood ratio CUSUM chart is better, especially this chart performs better when the censoring rate is low and the shape parameter value is small. Conversely, the binomial CUSUM chart is shown to perform better when the censoring rate is high, the shape parameter value is large, and the change in the mean is small.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.775-786
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• 2022

In the plant structures including nuclear power plants, penetrations are frequently installed in walls and slabs to reinforce facilities during operation, and reinforcing bars are sometimes cut off during concrete coring. Since these penetrations are not considered at the design or construction stage, cutting of reinforcing bar during opening installation is actually damage to the structure, structural integrity evaluation considering the stress transition range or effective width around the new penetration is necessary. In this study, various nonlinear analyses and static loading experiments are performed to evaluate the effect of reinforcing bar cutting that occurs when a penetration is newly installed in the shear wall of wall-type building of operating nuclear power plant. In addition, the decrease in wall stiffness due to the installed new penetration and cutting of reinforcing bars is evaluated and the stress and strain distributions of rebars around penetration are also measured.

• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.23-32
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• 1988

Finger injuries are becoming more common with the increasing use of mechanical industrial and household appliances. Among the hand injuries, amputation is the serious disaster to the patient. Recently, application of microsurgical technique to the reattachment of ampuatated digits has been common clinical procedures. We performed microsurgical replantation to the 75 patients with 102 digits from march in 1986 to february in 1988. The following results were obtained. 1. The most common age distribution was third decade and male to female ratio was about 5:1. 2. The ratio of right to left hand was about 1:1 but the dominant to non-dominant hand was about 2:1. 3. The index finger was most commonly injured and the next was middle finger. 4. The most common type of the injuries was the crushing injury and the most common vector was a kind of pressor. 5. The anesthesia was performed in equal ratio between the general and regional anesthesia. 6. The survival rate of microreplantation to the injuries of the zone II was 77.8% and zone III was 80%. 7. The functional result after replantation at zone II was better than zone III. 8. Microreplantation was performed in any case of the type of the injury, the severity of crushing and the ischemic time, and the patients requirement was an important factor.

• The Korean Journal of Applied Statistics
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• v.32 no.5
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• pp.693-702
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• 2019

Deep learning has gained popularity for the classification and prediction task. Neural network layers become deeper as more data becomes available. Saturation is the phenomenon that the gradient of an activation function gets closer to 0 and can happen when the value of weight is too big. Increased importance has been placed on the issue of saturation which limits the ability of weight to learn. To resolve this problem, Glorot and Bengio (Proceedings of the Thirteenth International Conference on Artificial Intelligence and Statistics, 249-256, 2010) claimed that efficient neural network training is possible when data flows variously between layers. They argued that variance over the output of each layer and variance over input of each layer are equal. They proposed a method of initialization that the variance of the output of each layer and the variance of the input should be the same. In this paper, we propose a new method of establishing initialization by adopting truncated normal distribution and truncated cauchy distribution. We decide where to truncate the distribution while adapting the initialization method by Glorot and Bengio (2010). Variances are made over output and input equal that are then accomplished by setting variances equal to the variance of truncated distribution. It manipulates the distribution so that the initial values of weights would not grow so large and with values that simultaneously get close to zero. To compare the performance of our proposed method with existing methods, we conducted experiments on MNIST and CIFAR-10 data using DNN and CNN. Our proposed method outperformed existing methods in terms of accuracy.

• The Korean Journal of Applied Statistics
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• v.26 no.4
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• pp.569-579
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• 2013

In the field of single-molecule spectroscopy, it is essential to analyze luminescence Intensity changes that result from a single molecule. With the CdSe/ZnS core-shell structured quantum dot photon emission data Bayesian multiple change-point estimation is done with the gamma prior for Poisson parameters and truncated Poisson distribution for the number of change-points.

• The Korean Journal of Rheology
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• v.6 no.2
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• pp.147-156
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• 1994

폴리프로필렌 이산화티타늄 첨가 폴리프로필렌을 심초형 복합 방사하여 첨가제를 섬유의 중심부분, 또 표면부분에 차별분포시켰다. TiO2의 함량이 증가함에 따라 점도(η)와 저장탄성계수(G＇)는 증가하였다. 전자현미경으로 파단면의 모폴로지를 관찰한 결과 TiO2와 함량이 증가함에 따라 감소하는 경향을 보였다. TiO2의 함량 증가에 따라 강력, 절단신도, 그리고 탄성계수는 감소하였다. 복합방사한 섬유의 TiO2 함량이 2% 미만일 때는 homo PP 보다 강력이 좋아졌다. 복합 섬유의 탄성계수는 중심부에 homo PP가 분포한 경우가 더 컸 고 강력과절단 신도는 중심부에 filled PP가 분포한 경우가 더 컸다.

• The Korean Journal of Applied Statistics
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• v.25 no.2
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• pp.311-319
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• 2012

The simplest and the most important distribution in survival analysis is exponential distribution. Koziol and Green (1976) derived Cram$\acute{e}$r-von Mises statistic's randomly censored version based on the Kaplan-Meier product limit estimate of the distribution function; however, it could not be practical for a real data set since the statistic is for testing a simple goodness of fit hypothesis. We generalized it to the composite hypothesis for exponentiality with an unknown scale parameter. We also considered the classical Kolmogorov-Smirnov statistic and generalized it by the exact same way. The two statistics are compared through a simulation study. As a result, we can see that the generalized Koziol-Green statistic has better power in most of the alternative distributions considered.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.129-138
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• 2019

Ammunition is an integral element of a weapon systems and in calculating fighting strength. The Korea Army utilizes the basic load (B/L) concept to supply ammunition smoothly. The required supply rate (RSR) is the basis of a B/L that is estimated from real combat data that includes a troop's mission and operation terrain. The current RSR is based on Korean War data and the sample mean has some problems in applications to modern combat. Therefore, this study used Korea Combat Training Center (KCTC) data that is similar to real combat to estimate rifle ammunition RSR. We used a quantile of truncated Weibull distribution to estimate rifle ammunition RSR considering that rifle ammunition consumption data in KCTC is truncated. As a result, we obtained a rifle ammunition RSR which covers most ammunition consumption by reflecting the individual consumption of rifle ammunition.