• Journal of Korean Society for Quality Management
• /
• v.35 no.2
• /
• pp.37-44
• /
• 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.

• Journal of the Korean Society for information Management
• /
• v.21 no.2
• /
• pp.45-67
• /
• 2004

The purposes of this study are to compare and analyze the evaluation indicators for selection of journal suggested by scholars and organizations and to prepare theoretical background for the ideal model to meet opposing paradigms of collection management in academic libraries. A web survey method was employed to investigate applications of various selection criteria (27 for printed and 37 for electronic academic Journal) from the top 40 academic libraries in Korea. In addition, data were analysed statistically using factor analysis, t-test, Analysis of Variance(ANOVA), and Spearman's Rank Oder Correlation. The mean ranking for 9 evaluation indicators for printed were as follows: subscribing volumes per departments, degree of use, selection authority, electronic/print bundle, ISI impact factor, Internationality and reputation, costs for subscription, ILL ＆ DDS, space considerations for printed materials. But, 11 evaluation indicators for electronic were as follows : costs for subscription, accessibility, electronic/print bundle, consortia, selection authority, access expandability, subscribing volumes per departments, scholarly features of the university, ISI impact factor, ILL ＆ DDS, internationality and reputations.

• The Korean Journal of Pain
• /
• v.30 no.4
• /
• pp.250-257
• /
• 2017

Vitamin D is a cofactor responsible for autoimmune disorders. There is no agreement in the studies investigating the association between vitamin D and fibromyalgia. This study aims to combine the conflicting results of the primary studies which compared these patients with control groups regarding the serum concentration of vitamin D. This meta-analysis has been designed based on PRISMA guidelines. Relevant keywords were searched in PubMed, Science direct, Scopus, Cochrane, and Google scholar and primary studies were selected. After screening the eligible studies according to inclusion/exclusion criteria, we investigated the risk of bias in the selected studies and also the heterogeneity between the primary results using Cochrane (Q) and I-squared ($I^2$) indices. The primary results were combined using inverse variance method and Cohen statistics as well as a random effects model. Publication bias was assessed using Egger test. Sensitivity analysis was applied to investigate the influence of each primary study on the final result of the meta-analysis. Suspected factors in the heterogeneity were assessed using meta-regression models. We entered 12 eligible studies in the meta-analysis including 851 cases compared with 862 controls. The standardized mean difference of Vitamin D between the two groups was -0.56 (95% confidence interval: -1.05, -0.08). Our meta-analysis showed that vitamin D serum levels of patients with fibromyalgia was significantly lower than that of control group.

• Korean Journal of Adult Nursing
• /
• v.29 no.1
• /
• pp.41-50
• /
• 2017

Purpose: The purpose of this study was to identify and compare the factors influencing attitude toward one's own aging among Korean middle-aged adults and the elderly. Methods: A cross sectional study was performed with a total sample of 70 middle-aged adults and 64 elderly reside in two metropolitan areas. Data were collected from August 2015 to November 2015 using the Perceived Health Status Scale, the Health Locus of Control Scale and the Attitude Toward own Aging (ATOA) Scale. The statistics used include percentage, t-test, Pearson's correlation coefficient, and multiple regression. Results: Mean age for each age group were about 52 and 76 years old for middle-aged adults and the elderly respectively. A considerable proportion of all participants reported a negative attitude toward aging. Perceived health status was the common factor influencing attitude toward one's own aging in both age groups. Middle-aged adults identified presence of chronic illness and internal health locus of control as important factors. In contrast, the elderly reported that education and others-dependent health locus of control such as powerful others had a significant impact on ATOA. Each regression model explained 31% and 55% of the total variance of ATOA among middle-aged adults and among the elderly. Conclusion: Both middle-aged adults and the elderly with low perceived health status are at risk of negative ATOA's. The type health locus of control need to be identified and utilized based on individuals' tendency to improve positive ATOA. That is, middle-aged adults might need reinforcement of their self-will whereas the elderly might need enhancement of social support and network of family and healthcare providers.

• Nuclear Engineering and Technology
• /
• v.38 no.2
• /
• pp.147-154
• /
• 2006

Thermal fatigue of the coolant circuits of PWR plants is a major issue for nuclear safety. The problem is especially accute in mixing zones, like T-junctions, where large differences in water temperature between the two inlets and high levels of turbulence can lead to large temperature fluctuations at the wall. Until recently, studies on the matter had been tackled at EDF using steady methods: the fluid flow was solved with a CFD code using an averaged turbulence model, which led to the knowledge of the mean temperature and temperature variance at each point of the wall. But, being based on averaged quantities, this method could not reproduce the unsteady and 3D effects of the problem, like phase lag in temperature oscillations between two points, which can generate important stresses. Benefiting from advances in computer power and turbulence modelling, a new methodology is now applied, that allows to take these effects into account. The CFD tool Code_Saturne, developped at EDF, is used to solve the fluid flow using an unsteady L.E.S. approach. It is coupled with the thermal code Syrthes, which propagates the temperature fluctuations into the wall thickness. The instantaneous temperature field inside the wall can then be extracted and used for structure mechanics computations (mainly with EDF thermomechanics tool Code_Aster). The purpose of this paper is to present the application of this methodology to the simulation of a straight T-junction mock-up, similar to the Residual Heat Remover (RHR) junction found in N4 type PWR nuclear plants, and designed to study thermal striping and cracks propagation. The results are generally in good agreement with the measurements; yet, in certain areas of the flow, progress is still needed in L.E.S. modelling and in the treatment of instantaneous heat transfer at the wall.

• Journal of Korean Society for Geospatial Information Science
• /
• v.20 no.1
• /
• pp.13-20
• /
• 2012

In this study, the change pattern of hydrological response function as development has been observed. The target watershed was selected Tanbu sub-Basin in the Bocheong Basin. The applied channel networks are composed of 10 cases that are channel networks by strahler's ordering scheme and cases of all grids channel or the hillslope in basin. To each case of grid in basin, channel and hillslope drainage path lengths to outlet of basin are calculated, and hydrological response function was calculated by Nash Model. As results of this analysis, the peak discharge of hydrological response function is increased and peak time is shortened as development of channel networks. And based on statistical characteristics of hydrological response function, mean (lag time) and variance of travel time are reduced exponentially.

• The Journal of Advanced Prosthodontics
• /
• v.6 no.1
• /
• pp.39-45
• /
• 2014

PURPOSE. The aim of the present study was to evaluate the accuracy of three techniques for correction of cast implant bars. MATERIALS AND METHODS. Thirty cast implant bars were fabricated on a metal master model. All cast implant bars were sectioned at 5 mm from the left gold cylinder using a disk of 0.3 mm thickness, and then each group of ten specimens was corrected by gas-air torch soldering, laser welding, and additional casting technique. Three dimensional evaluation including horizontal, vertical, and twisting measurements was based on measurement and comparison of (1) gap distances of the right abutment replica-gold cylinder interface at buccal, distal, lingual side, (2) changes of bar length, and (3) axis angle changes of the right gold cylinders at the step of the post-correction measurements on the three groups with a contact and non-contact coordinate measuring machine. One-way analysis of variance (ANOVA) and paired t-test were performed at the significance level of 5%. RESULTS. Gap distances of the cast implant bars after correction procedure showed no statistically significant difference among groups. Changes in bar length between pre-casting and post-correction measurement were statistically significance among groups. Axis angle changes of the right gold cylinders were not statistically significance among groups. CONCLUSION. There was no statistical significance among three techniques in horizontal, vertical and axial errors. But, gas-air torch soldering technique showed the most consistent and accurate trend in the correction of implant bar error. However, Laser welding technique, showed a large mean and standard deviation in vertical and twisting measurement and might be technique-sensitive method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.6
• /
• pp.538-545
• /
• 2002

In the orthogonal frequency division multiplexing (OFDM) system, the nonlinear distortion in the high power amplifier(HPA) degrades the system performance because of the high peak-to-average power ratio (PAPR). In this paper, a semi-analytical method is newly proposed for the performance evaluation of the nonlinearly distorted OFDM communication system. In the proposed method, at first, the probability density function (pdf) of the PAPR is generated by computer simulation. Then, mean and variance of the non-linear distortion noise process are computed. Next, the overall BER is found by the analytical method. When the equivalent SSPA model is applied in case of the QPSK/16-QAM and AWGN channel, the BER is calculated for the variation of the IBO(input back-off) and PAPR parameter. It is shown that the results by proposed method are very similar to those of the conventional Monte-Carlo method. The computation time can be considerably reduced than the conventional method that depends on the magnitudes of BER and IBO.

• Journal of dental hygiene science
• /
• v.18 no.3
• /
• pp.137-146
• /
• 2018

This systematic review aimed to investigate the effects of periodontal treatment on glycated hemoglobin A (HbA1c) levels in patients with type 2 diabetes who develop periodontal disease. The search of the MEDLINE, Embase, CINAHL, and Cochrane Library databases was completed on April 8, 2018. The study design was based on randomized clinical trials. Scaling and root planing was performed for the test group, whereas no periodontal treatment or simple oral training was performed for the control group. The main outcome variable was the change in HbA1c levels. We used the Review Manager statistical analysis software for the quantitative analysis of selected documents. Meta-analysis was performed using the inverse variance estimation method of the fixed-effect model to estimate the effects of periodontal treatment on HbA1c levels in patients with type 2 diabetes. A total of 1,011 documents were searched using search strategies, and 10 documents were included in the meta-analysis. The meta-analysis of the selected literature showed that periodontal treatment significantly reduced the HbA1c levels in patients with type 2 diabetes who develop periodontal disease (mean difference, -0.34; 95% confidence interval, -0.43 to -0.26; p<0.001). This study aimed to investigate the effects of periodontal treatment on HbA1c levels, which can be used as a basis for the increasing management of diabetic complications. To improve the quality of life and reduce the burden of medical expenses for patients with diabetes, periodontal disease management through nonsurgical periodontal treatment, such as scaling and root planing, is necessary.

• Journal of Korean Biological Nursing Science
• /
• v.19 no.2
• /
• pp.113-122
• /
• 2017

Purpose: The purpose of this study was to identify influencing factors on rehabilitation adherence in stroke patients. Methods: This study was a descriptive survey. A structured questionnaire was used for face-to-face interviews with a convenient sample of 192 subjects, who were admitted in 5 rehabilitation hospitals located in G metropolitan city. Results: The score of rehabilitation motivation in the subjects was a mean of $2.04{\pm}0.35$, self-efficacy $6.22{\pm}2.32$, family support $3.40{\pm}0.82$ and rehabilitation adherence $3.08{\pm}0.41$. The rehabilitation adherence was a statistically significant difference according to the education level (F= 3.40, p= .035), marital status (F= 4.04, p= .019), number of personal insurance policies (K= 9.80, p= .020), location of paresis (F= 2.72, p= .046), and status of current smoking (M = 657.00, p= .001). There was significant correlation among degree of rehabilitation adherence, rehabilitation motivation (r= .30, p< .001), self-efficacy (r= .14, p= .046) and family support (r= .18, p= .011). Rehabilitation motivation (${\beta}=0.19$, p= .007), self-efficacy (${\beta}=0.14$, p= .035), marital status (${\beta}=0.14$, p= .038), number of personal insurance policies (${\beta}=-0.15$, p= .045) and location of paresis(${\beta}=-0.15$, p= .028) were identified as significant predictors. This model explained 22.6% of variance in rehabilitation adherence (F= 5.92, p< .001). Conclusion: There is a need to develop an effective intervention for rehabilitation adherence improvement considering the identified variables in this study.