• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.315-323
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• 2004

In this paper we present a method to generate the bit stream of static video test patterns for testing the picture quality in DTV system. The proposed user-defined quantization table is suitable for the static video test pattern and for minimizing the deterioration of picture quality by quantization, the underflow or overflow of video buffer generated on the process of coding the static video test pattern is compensated by a adaptive zero stuffing algorithm so that optimal picture quality is implemented. Experimental result showed that the test pattern stream encoded by MPEG-2 software with the proposed algorithm had a stable bit rate and good video quality during the decoding process, which is about 3 dB higher than that of the conventional case.

• Journal of Korean Society for Quality Management
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• v.31 no.4
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• pp.19-35
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• 2003

With the increase in family income in Korea and the improving quality of life, there is a rapid growth in the restaurant industry. Therefore there is a demand for quality service in this industry. This paper reviews the relationship between service quality and the degree of employee empowerment. The first objective of this research is to test the effects of employee empowerment on service quality, and the second one is to test how tenure affects this relationship. According to statistical analysis, meaning, competency, and autonomy generally have an affirmative impact on many service quality factors. Also the results of regression analysis to test the moderation effect show that long term employees are more sensitive to autonomy than short term employees.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.3
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• pp.56-65
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• 2001

In interpreting stream water quality data, scientific or statistical mehtods should be employed. Classical parametric statistical methods may not be adopted in analyzing water quality data, due to the violation of normality. In this study, nonparametric statistical methods, such as Kruskal-Wallis test and Mann-Whitney test, were used in comparing water quality data from several monitoring stations. Water quality data used are those collected Bokha watershed, located in Ichon-city, Kyonggi province. Based on the test results, domestic sewage is the major pollution source. A couple of sub-watersheds with a large number of livestock do not show significant differences in water quality parameters. It should be noted that comparison of mean values of water quality parameters is difficult to relate water quality with watershed characteristics. The results also indicate that livestock farming does not significantly affect the water quality.

• Journal of Korean Society for Quality Management
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• v.30 no.1
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• pp.74-96
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• 2002

The objectives of this study is to suggest the rectifying sampling inspection plan considering quality cost. Limiting quality level(LQL) plans(also called LTPD plans) and outgoing quality(OQ) plans are considered. The Hald's linear cost model is discussed with and without a beta prior for the distribution of the fraction of nonconforming items in a lot. It is assumed that the sampling inspection is error free. We consider the design of reliability acceptance sampling plan (RASP) for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and K C 6032 standards provide this procedures. But these procedures have some questions to apply in the field. The cost of test and confidence level(1-$\beta$ risk) are the problem between supplier and user. So, we suggest that the optimal life test sampling inspection plans using simple linear cost model considering product cost, capability of environment chamber, environmental test cost, and etc. Especially, we consider a reliability of lots that contain some nonconforming items. In this case we assumed that a nonconforming item fail after environmental life test. Finally, we develope the algorithm of the optimal sampling inspection plan based on minimum costs for rectifying inspection and RASP. And computer application programs are developed So, it is shown how the desired sampling plan can be easily found.

• Journal of Korean Society for Quality Management
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• v.42 no.1
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• pp.33-41
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• 2014

Purpose: The purpose of this paper is estimate response quality of three major portal in Korea based on the response time. In addition to response time, the response time by 1Kbyte will be analysed. Methods: Data was collected from July 2010 to November 2013 using Firebug. For comparing averages, ANOVA will be used. For comparing distributions, Chisquare test and Kolmogov-Smirnov test will be used for parametric and non parametric test respectively. Results: For response quality based on response time, Daum gets the first place, Naver the second place, and Nate the third place. But the order of the response time per 1Kbyte is different. The order is Naver, Daum and Nate. Conclusion: The response quality may be estimated using various factors. Response time is the most important factor. Daum provides the shortest response time. We could say Daum provides the best response quality. But Naver provides the shortest response time per 1Kbyte. From these results, we know reducing packets is very important thing in response time.

• Journal of Environmental Impact Assessment
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• v.4 no.2
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• pp.93-103
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• 1995

This study was carried out to suggest the best statistical test to analyze the trend in monthly water quality data. Traditional parametric tests such as t-test and regression analysis are based on the assumption that the underlying population has a normal distribution and regression analysis additionally assumes that residual errors are independent. Analyzing 9-years monthly COD data collected at Paldang in Han River, the underlying population was found to be neither normal nor independent. Therefore parametric tests are invalid for trend detection. Four Kinds of nonparametric statistical tests, such as Run Test, Daniel test, Mann-Kendall test, and Time Series Residual Analysis were applied to analyze the trend in the COD data, Daniel test and Mann-Kendall test indicated upward trend in COD data. The best nonparametric test was suggested to be Daniel test, which is simple in computation and easy to understand the intuitive meaning.

• Korean Journal of Veterinary Service
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• v.41 no.2
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• pp.63-69
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• 2018

This study was conducted to evaluate the effect of tuberculin test and associated various environmental factors on the quantity and quality of milk production of daily cows. The change of milk quantity followed to tuberculin test was investigated on 109 daily farms in south Gyeonggi, and the change of milk quality was also studied on 48 daily farms. The result of this study showed that the quantity and quality of milk production was decreased after tuberculin test (P<0.05). The amount of loss of the milk production due to tuberculin test was, however, only 0.92 L per cow. In terms of milk quality, the level of total protein was statistically significantly decreased. This study also showed that the milk quality was further decreased when the cows were restraint after veterinarians arrived compared to the case that cows were stayed restraint before the veterinarians visited the farm. In addition, milk quality and quantity were lowered worse when relative humidity of the location of tuberculin test was lower than 50% or higher than 70%, or when the milk production of a farm is higher than its quarter. This study showed that stress on daily cows and the farmers induces the decrease of milk yield and milk quality, and these losses can be minimized by regulating various environmental factors to the direction to maximize productivity.

• Journal of Digital Contents Society
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• v.13 no.4
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• pp.625-629
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• 2012

This paper is presented to prepare NGN quality assurance management process under the quality system test methodology. The process should be drawn for NGN quality measurement framework of multimedia traffic. NGN test bed management process model are QoS measurement metrics, measurement interval meter above, and measuring tools, measuring equipment, measurement methods and measurement results from a series of processes for the analysis and methodology. This model, NGN quality assurance activities should be utilized in the future. Quality target level only when themselves constantly measured and managed, does not guarantee the communication quality of service. It is sensitive to the importance of NGN network technology paradigm for research on quality management in the NGN.

• Journal of Korean Society for Quality Management
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• v.52 no.1
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• pp.135-148
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• 2024

Purpose: This study is to investigate the literature on accelerated tests based on the acceleration model and to provide a compilation of results on the parameters applied in the acceleration model and the test conditions. Methods: This research is conducts a literature review on accelerated tests using the acceleration model, with a focus on test targets, test conditions, and parameter values. The study is organizing the results of this literature review to facilitate their application in the design of reliability tests. Results: A literature review investigated a variety of test targets, test conditions, and parameter values. Conclusion: The results of the literature research conducted revealed various acceleration model parameter. Such literature research on accelerated tests can establish the foundation for reliability test design and contribute to future product development and quality improvement

• Sleep Medicine and Psychophysiology
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• v.27 no.1
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• pp.16-23
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• 2020

Objectives: Sleep disturbance in the elderly is associated with cognitive decline. Sleep quality is known to deteriorate with age, and prospective studies seldom have examined the relationship between sleep quality and cognitive function. This study investigates the relationship between early sleep quality and cognitive function based on six-year follow-up data of community individuals older than 60 years. Methods: The participants included 622 community elderly people older than 60 years from Jinju-Si. The final analysis comprised 322 elderly people. Pittsburgh sleep quality index (PSQI) and the Korean version of Consortium to Establish a Registry for Alzheimer's Disease (CERAD-K) were used to assess early sleep quality and cognitive function after six years. Multiple linear regression analysis was performed to investigate the association between early sleep quality and cognitive function in the elderly. Results: Early sleep quality (PSQI) was significantly associated with the results of the digit span test, clock drawing test (clox 1), and word recall test after six years. Sleep quality (PSQI) decreased significantly after six years, and lower quality of sleep (PSQI) score was associated with higher digit span test score (β = -0.167, p = 0.026) and higher clock drawing test score (β = -0.157, p = 0.031). Lower quality of sleep (PSQI) score was associated with higher word recall test (β = -0.140, p = 0.039). Conclusion: The digit span test, word recall test, and clock drawing task (CLOX 1) shown to be significantly associated to sleep quality can be performed fast and easily in clinical practice. It is important to assess early cognitive function in the elderly with poor sleep quality, and further studies could suggest that these tests may be useful screening tests for early dementia in elderly with poor sleep quality.