• Journal of Applied Reliability
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• v.12 no.3
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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.

• Journal of Korean Society for Quality Management
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• v.39 no.2
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• pp.313-319
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• 2011

In design verification and process validation stages, reliability demonstration tests(RDT's) are common practice in industry, A new two-stage RDT that is known to be more efficient than a corresponding single-stage one in terms of expected test duration for Weibull distribution is proposed. Zero or one failure two-stage plans to minimize expected test duration under Type I and hybrid censoring subject to satisfying consumer's risk at a specified reliability target are developed and a numerical example is provided to illustrate the proposed two-stage RDT plans and compared with other one- and two-stage plans.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.4
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• pp.25-35
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• 2017

This study aimed to analyze a driver's night visibility, according to the installation of a lighting system for driving an agricultural machine during the night time. For the night visibility analysis, a luminance measurement test on the lighting system and a gaze duration measurement test through eye movement measurement devices were carried out. In the luminance measurement test, the increase of luminance was confirmed as relative distance from an agricultural machine was closer and the conditions of the lighting equivalence are improved. Also the gaze duration measurement test, total gaze duration from an agricultural machine increased, as the conditions of the lighting equivalence are improved. In addition, it was identified that the difference in average gaze duration from an agricultural machine was statistically significant as the agricultural machine was driven in high speed. In conclusion, when the lighting system is installed on an agricultural machine, a driver's night visibility from the agricultural machine improves, which is expected to be enormously helpful to the prevention of agricultural machine accidents.

• Korea-Australia Rheology Journal
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• v.20 no.1
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• pp.35-42
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• 2008

An inverse ferrofluid composed of micron sized polymethylmethacrylate particles dispersed in ferrofluid was used to investigate the effects of test duration times on determining the flow curves of these materials under constant magnetic field. The results showed that flow curves determined using low duration times were most likely not measuring the steady state rheological response. However, at longer duration times, which are expected to correspond more to steady state behaviour, we noticed the occurrence of plateau and decreasing flow curves in the shear rate range of $0.004\;s^{-1}$ to ${\sim}20\;s^{-1}$, which suggest the presence of nonhomogeneities and shear localization in the material. This behaviour was also reflected in the steady state results from shear start up tests performed over the same range of shear rates. The results indicate that care is required when interpreting flow curves obtained for inverse ferrofluids.

• Child Health Nursing Research
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• v.17 no.2
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• pp.145-152
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• 2011

Purpose: To evaluate the efficacy of Optimal humidification during Nasal Continuous Positive Airway Pressure (nCPAP) for Extremely Low Birth Weight Infant (ELBWI). Methods: The study design was a pre-test-post-test nonequivalent nonsynchronized quasi-experimental design. The participants were 218 ELBWI on nCPAP (experimental group: 102 and control group: 116). Data collection was conducted from January 2005 to April 2010. In order to measure and analyze the nCPAP duration, reintubation and nasal condition, Chi-square test and t-test were used. Results: Hypothesis 1, that the duration with nCPAP in the experimental group is longer than that of the control group and hypothesis 2-3, that the rate of reintubation and nasal problems in the experimental group are lower than the control group, were all supported as there were statistically significant differences between two groups. Conclusion: The findings suggest that the Optimal humidification in this study is an efficient intervention because it helps increase the last time of nCPAP with ELBWI and minimize complications. It is expected that Optimal humidification is beneficial and helpful in preventing and caring for respiratory problems in these infants.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.2
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• pp.121-128
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• 2004

This paper presents a new approach for determining an accurate incentive levels of Direct Load Control (DLC) program using sequential Monte Carlo Simulation (MCS) techniques. The economic analysis of DLC resources needs to identify the hourly-by-hourly expected energy-not-served resulting from the random outage characteristics of generators as well as to reflect the availability and duration of DLC resources, which results the computational explosion. Therefore, the conventional methods are based on the scenario approaches to reduce the computation time as well as to avoid the complexity of economic studies. In this paper, we have developed a new technique based on the sequential MCS to evaluate the required expected load control amount in each hour and to decide the incentive level satisfying the economic constraints. In addition, the mathematical formulation for DLC programs' economic evaluations are developed. To show the efficiency and effectiveness of the suggested method, the numerical studies have been performed for the modified IEEE reliability test system.

• Korean Journal of Clinical Pharmacy
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• v.24 no.1
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• pp.9-14
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• 2014

Background: It is known to reduce the mortality when glutamine is supplied to patients during the surgery or in intensive care unit through intravenous nutrition supply. The purpose of this study is to establish the appropriate basis for use of glutamine and guidelines of nutrition supply for critically ill patients in the hospital by examining the clinical effects of administration of glutamine with subjects of elderly critically ill patients receiving intravenous nutrition in one hospital in Korea. Method: Among elderly patients with age of 60 or more hospitalized in Yeuido St. Mary's Hospital from August 2012 to July 2013, those who stayed in the intensive care unit for more than a week and received TPN (Total Parenteral Nutrition) for more than 3 days during staying in the intensive care unit were classified to a test group using glutamine and a control group without glutamine. Duration of use of mechanical ventilator, duration of hospitalization, occurrence of infectious disease and death were compared between two groups. We would like to identify the clinical test figures affected by the use of glutamine by examining changes in SCr, Total Protein, Albumin, AST, ALT, TB, DB and GFR at the time of admission and discharge. Results: At the time of admission to intensive care unit, gender, physical measurement information and clinical test figures did not show any significant difference between 72 subjects in a test group and 24 subjects in a control group. Thus, two groups began in the same condition. There were no significant difference in duration of hospitalization, duration of intensive care unit, use of mechanical ventilator, occurrence of infectious disease and death. As the results of statistical analysis of the average changes of clinical test figures at the time of admission and discharge of intensive care unit, SCr and GFR were significantly changed in the test group. GFR was significantly changed in a control group. As the result of analysis of the clinical test figures at the time of discharge with reflection of average changes after clinical test figures were corrected at the time of admission of intensive care unit, TB and GFR were significantly increased in a test group compared with those in a control group. Other clinical test figures were not significantly changed. Conclusion: If glutamine is administered to critically ill patients over age 60 receiving TPN and careful monitoring for total bilirubin is made in the future, it is expected to give the positive effect on renal function andminimize the side effect of arise in total bilirubin.

• Journal of the Korean Home Economics Association
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• v.40 no.5
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• pp.109-118
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• 2002

This study focused on the relationship among perceived social support from care teacher(institution staff), internal locus of control, and school adjustment of institutionalized children. This also examined the differences of perceived social support, internal thou of control, and school adjustment by gender and the duration in the institution. Participant were 119 fifth-and sixth-grade elementary school studens(58 boys, 61 girts). Perceived social support from care teacher, internal locus of control, and school adjustment were measured by self-reports of institutionalized children. The data were analyzed, in SPSS Win program, by Cronbach's α, T-test, Pearson Correlations, Simple Regression, Hierarchical Multiple Regression. As expected, results confirm that perceived social support was associated positively with internal locus of control and school adjustment. further, perceived social support also exerts indirect effects on school adjustment, mediated by internal locus of control. However, none of these variables differed by gender and the duration in the institution.

• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.360-371
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• 2013

Fast delivery of construction projects provides more value to project owners. Batch production, which is production not in single pieces, but in batches, is a common approach in repetitive construction projects such as multi-unit residential building construction projects. In batch production, the use of a small batch size allows the early start of subsequent activities, and thus can lead to early completion of projects. In addition to batch size, balance between productivities in construction activities can affect project duration. However, the impact of the balance between productivities with regard to their order on project duration has not been studied. The main goal of this study is to test a hypothesis, which is that the order of construction activities' unbalanced productivities affects the amount of time reduction that can be achieved by using a small batch size. A computer-based simulation model was developed, and five different cases were simulated to test the hypothesis. The conclusion of the simulation result is that the order of productivities does not affect the time reduction achieved by using a small batch size. It is expected that the findings of this study can help general contractors make decisions in terms of batch size.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.695-699
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• 2009

As a rule, when develop new product in company, multiple products that have similar function are developed simultaneously. These products are subjected to a group of tests covering quality, safety and durability. If the schedule of tests is changed, the expected net presented value(NPV) of new products is changed. The tests should be scheduled with the goal of maximizing the expected NPV of the new products. A model incorporated resource constraints with the sequencing of testing tasks of multiple products is proposed in this paper. Examples show that the proposed model can handle stochastic task duration data represented by scenarios with probabilities.