• 한국통신학회논문지
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• 제29권2C호
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• pp.315-323
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• 2004

본 논문은 디지털 TV 시스템의 화질 테스트를 위해 사용될 수 있는 정적 비디오 테스트 패턴에 대한 고화질 스트림을 생성할 수 있는 방법을 제안하고 있다. 이를 위해 정적 비디오 테스트 패턴의 부호화에 적합하고 양자화로 인한 화질의 손실을 최소화할 수 있는 사용자 양자화 테이블을 제안하고 있으며, 정적 테스트 패턴의 부호화 과정에서 발생할 수 있는 비디오 버퍼의 넘침 및 고갈 현상을 적응적인 제로 추가 방법을 이용하여 해결함으로써 최적의 화질을 구현하였다. 제안한 알고리즘을 실험해 본 결과 안정된 전송률을 나타낼 뿐만 아니라 화질 또한 멀티버스트 패턴에서 기존 방식 보다 약 3 dB 정도의 우수함을 보여 DTV 시스템의 테스트에 적합함을 알 수 있었다.

• 품질경영학회지
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• 제31권4호
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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.

• 한국농공학회지
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• 제43권3호
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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.

• 품질경영학회지
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• 제30권1호
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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.

• 품질경영학회지
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• 제42권1호
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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.

• 환경영향평가
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• 제4권2호
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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.

• 한국동물위생학회지
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• 제41권2호
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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.

• 디지털콘텐츠학회 논문지
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• 제13권4호
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• pp.625-629
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• 2012

NGN 운용과정의 품질 보증을 위해 어떤 체계하에서 품질이 테스트 되어야 하는지 방법론을 도출하기 위해서 멀티미디어 트래픽을 중심으로 NGN 품질측정 프레임워크를 제시한다. 테스트베드는 NGN 운용과정에서 QoS 측정 메트릭스, 측정구간과 측정계위, 측정도구, 측정장비, 측정방법 및 측정결과 분석에 대한 일련의 프로세스와 방법론을 모델화한다. 이 모델은 향후 NGN 품질보증 활동에 활용토록 한다. 통신서비스 품질은 스스로 보장되지 않으며 끊임없이 측정되고 관리될 때에 만 품질 목표수준 확보가 가능하다. NGN 네트워크기술 패러다임 중요성을 감한할 때 NGN 운용상의 품질관리에 대한 연구는 앞으로 활발하게 추진되어야 할 핵심 소재이다.

• 품질경영학회지
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• 제52권1호
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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

• 수면정신생리
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• 제27권1호
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• pp.16-23
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• 2020

목 적 : 나이가 들수록 수면의 질은 나빠진다고 알려져 있으며 수면의 질과 인지기능 사이의 관계를 조사한 전향적 연구는 현재까지 거의 없었다. 본 연구에서는 60세 이상의 지역사회 노인을 대상으로 6년 동안 추적 조사한 자료를 바탕으로 초기 수면의 질과 인지기능 사이의 관련성을 알아보고자 하였다. 방 법 : 본 연구에서는 60세 이상의 지역사회 노인 622명을 대상으로 하였고 최종 분석에는 322명의 노인이 포함되었다. 다음과 같은 임상척도가 사용되었다. 피츠버그 수면질 척도(Pittsburgh sleep quality index, PSQI)와 한국판 신경심리 평가집(Korean version of Consortium to Establisha Registry for Alzheimer's Disease, CERAD-K). 초기 수면의 질과 6년 이후의 인지기능의 관련성을 평가하기 위해 다중 선형 회귀분석을 시행하였다. 결 과 : 초기 수면의 질(PSQI)은 6년 이후의 숫자 외우기 검사(digit span test), 시계그리기 검사(CLOX 1), 단어 목록 회상 검사(word recall test)의 결과와 유의한 관련성이 있었다. 수면의 질이 좋을수록(β = -0.167, p = 0.026) 숫자외우기 검사 점수가 증가했으며 수면의 질이 좋을수록(β = -0.157, p = 0.031) 시계 그리기 점수(CLOX 1)가 증가했다. 또한 수면의 질이 좋을수록(β = -0.140, p = 0.039) 단어 목록 회상 검사 점수(word recall test)가 증가했다. 결 론 : 본 연구에서 수면의 질과 유의한 관련성이 있는 나온 숫자외우기 검사(digit span test), 단어목록 회상 검사(word list recall), 시계 그리기 검사 (CLOX 1)는 임상에서 비교적 단시간 내에 간편하게 수행 할 수 있는 검사이다. 수면의 질이 낮은 노인을 대상으로 이른 시기에 인지기능을 평가하는 것은 중요하며 추후 위의 3가지 검사가 수면의 질이 낮은 노인에게 조기 치매 진단의 유용한 선별검사가 될 수 있음을 밝히는 연구가 더 진행되어야 할 것이다.