• 유공압시스템학회논문집
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• 제3권3호
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• pp.8-13
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• 2006

It is very important for the manufacturers to predict the life of hydraulic system components according to the results of life tests. Since it takes too much time to test the hydraulic system components until failure, the no-failure test method is applied for the life test of them. If the shape parameter of Weibull distribution, the number of samples, the confidence level, and the assurance life are given, the no-failure test times of hydraulic system components can be calculated by given equation. Here, the procedures to obtain the no-failure test times of the hydraulic system components such as hydraulic motors and pumps, hydraulic cylinders, hydraulic valves, hydraulic accumulators, hydraulic hoses, and hydraulic filters are described briefly.

• Journal of Animal Science and Technology
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• 제46권6호
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• pp.999-1006
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• 2004

NPC agar， DHL agar, MacConkey agar와 Cetrimide desoxycholate agar의 선택성을 조사 하였다". Cetrimide desoxycholate agarz 가 다른 선택성 배지에 비해 그람양성 세균을 억제하고 Pseudomonas를 비롯한 내냉성 그람음성 세균의 선택적 배양에 더 좋은 한천배지이었다. Resazurin 환원시간 검시에서 Cetrimide desoxycholate broth를 시유와 혼합하여 $21^{\circ}C$ 에 서 18 시간 배양한 후 resazurin을 첨가하여 변색되는 시간으로 2차오염 을 결정하는 방법으로서 조사하였다. Resazurin 환원시간 검사와 저장성 검사간에 81%의 관련성이 있었다. 저장성 검사의 우유에서 Pseudomonas가 가장 먼도 높게 분리되었으며 다음으로 Acinetobacter와 Aeromonas가 검출되었다 Resazurin 환원시간 검사에는 Acinetobacter, Pseudomonas, Enterobacter의 순서의 빈도로 검출되었다.

• Applied Science and Convergence Technology
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• 제24권5호
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• pp.132-135
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• 2015

Schematic of RAON vacuum system is introduced. Vacuum test for superconducting cavity with liquid nitrogen is performed. Schematic plan for RAON vacuum system is introduced and vacuum control system for superconducting cavity test is constructed. Vacuum pressure of cavity is shown as a function of pumping time. The temperature of cavity is shown as a function of cooling time. Outgassing species from cavity is also detected. Detailed experimental procedure is presented to test the cavity vacuum with liquid nitrogen.

• 한국신뢰성학회지:신뢰성응용연구
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• 제12권3호
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• pp.139-152
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• 2012

Successive and simultaneous sudden death tests are compared with the complete and Type II censored samples in terms of expected test duration and Total Time on Test(TTT) subject to the same number of failures in order to maintain the equal statistical precision under Weibull lifetime distribution with known shape parameter. Also, two sudden death tests under a proposed cost model are discussed and a numerical example is provided to illustrate the use of the proposed cost model.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2005년도 추계학술대회
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• pp.135-138
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• 2005

In this paper, we consider the problem of testing for parameter change in time series models based on a cusum of squares. Although the test procedure is well-established for the mean and variance in time series models, a general parameter case was not discussed in literatures. Therefore, here we develop the cusum of squares type test for parameter change in a more general framework. As an example, we consider the change of the parameters in an RCA(1) model. Simulation results are reported for illustration.

• 가족자원경영과 정책
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• 제22권3호
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• pp.1-19
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• 2018

This study was aimed at exploring gender differences in time use and time famine between single-parent families. Data were obtained from the time use surveys, that were conducted by the Korea National Statistical Office in 2014. A total of 500 time diaries (168 from fathers, 332 from mothers) from single-parents aged between 20 and 59 were analyzed. Descriptive statistics, chi-square test, and t-test were used for the statistical analyses. Results indicated that the single-parent families exhibit gender differences in time use and subjective time famine. The single-mothers spend a significantly longer amount of time on housework and less time on leisure than do the single-fathers. The single fathers and mothers also differ in time use and time famine according to employment status and working days on/off.

• 한국지반환경공학회 논문집
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• 제18권2호
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• pp.59-65
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• 2017

해양 매립 공사는 해저의 해성점토를 해수와 함께 준설하여 매립지로 이동시켜 매립지를 형성시키는 공사이다. 매립지가 형성되는 과정에서 준설토는 침강-퇴적-압밀 과정이 진행되며 이 과정에서 압밀과정은 소요되는 시간과 침하량이 크기 때문에 매립지를 계획하는 해양 매립 공사에서 매우 중요한 결정인자로 사용하게 된다. 준설토의 침하량과 소요되는 시간을 예측하기 위한 방법으로 국내에선 Yano가 제안한 Column 실험이 보편적으로 사용되고 있다. 그러나 Yano의 Column 실험은 준설토의 침강압밀특성을 확인하기 위해 장시간이 필요한 단점이 있다. 따라서 본 연구에서는 장시간이 소요되는 Column 실험의 단점을 보완해 단시간에 준설토의 침강압밀특성을 확인하기 위한 방법으로 원심모형실험을 활용하였다. 그 결과 효율적으로 준설토의 침강압밀특성을 확인하기 위해 원심모형실험을 활용할 수 있는 것으로 사료된다.

• 산업경영시스템학회지
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• 제45권4호
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• pp.53-60
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• 2022

In a group-testing method, instead of testing a sample, for example, blood individually, a batch of samples are pooled and tested simultaneously. If the pooled test is positive (or defective), each sample is tested individually. However, if negative (or good), the test is terminated at one pooled test because all samples in the batch are negative. This paper considers a queueing system with a two-stage group-testing policy. Samples arrive at the system according to a Poisson process. The system has a single server which starts a two-stage group test in a batch whenever the number of samples in the system reaches exactly a predetermined size. In the first stage, samples are pooled and tested simultaneously. If the pooled test is negative, the test is terminated. However, if positive, the samples are divided into two equally sized subgroups and each subgroup is applied to a group test in the second stage, respectively. The server performs pooled tests and individual tests sequentially. The testing time of a sample and a batch follow general distributions, respectively. In this paper, we derive the steady-state probability generating function of the system size at an arbitrary time, applying a bulk queuing model. In addition, we present queuing performance metrics such as the offered load, output rate, allowable input rate, and mean waiting time. In numerical examples with various prevalence rates, we show that the second-stage group-testing system can be more efficient than a one-stage group-testing system or an individual-testing system in terms of the allowable input rates and the waiting time. The two-stage group-testing system considered in this paper is very simple, so it is expected to be applicable in the field of COVID-19.

• 대한의생명과학회지
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• 제26권3호
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• pp.210-216
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• 2020

The purpose of this study was to evaluate GDH & Toxin (GDT) tests for the identification of the presence of Clostridioides difficile (C. difficile) as well as to detect whether any toxin was present in the feces of patients suspected of diarrhea associated with C. difficile. Data related to the results of toxin and culture (TC) tests and GDT tests conducted on patients with diarrhea and suspected CDI between January 2017 and august 2018, positive test rates, patient ages and sexes, whether the patients were hospitalized, and turnaround time (TAT) were analyzed retrospectively. Of the 7,554 total tests conducted for CDI diagnosis, 1,010 TC tests (14.9%) were positive, while 92 GDT tests (12.0%) were positive. Of these positive cases, 815 (80.7%) identified through TC test and 80 (87%) identified through GDT test were inpatients. also, among the patients with positive test results, 497 (49.2%) diagnosed through TC test and 45 (48.9%) diagnosed through GDT test were aged 61 years or older. The total time required to complete a TC test was 83.6 hours, while the time required for a GDT test was 11.2 hours, equating to an approximately three-day difference between the two tests. The detection of toxin-producing C. difficile is important in CDI diagnosis, but the commonly used Enzymeimmunoassay (EIA) toxin tests with low sensitivity result in delayed CDI diagnosis time. Therefore, primary screening tests for CDI diagnosis using the GDT method and secondary tests using additional methods are considered most effective.

• 가족자원경영과 정책
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• 제19권4호
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• pp.141-161
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• 2015

The purpose of this study was to explore the differences in time perspective by socio-demographic variables and to investigate the effect of time perspective on time management and life satisfaction for college students. Questionnaires including time perspective, time management, and life satisfaction scales were used for this study. The survey data from 382 college students were analyzed by frequency, percentage, mean, standard deviation, t-test, ANOVA, Duncan test, Pearson's correlation analysis, and stepwise regression. The time perspective, composed of four factors future insensibility and present, past, and future orientation, differed according to the sex, academic grade, and specialty of the college students. The time perspective of the college students and the socioeconomic status of their households were investigated as effective variables on time management and life satisfaction. Based on these results, the implications for research and policy on the time perspective of college students were discussed.