• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.303-309
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• 1999

The fretting wear behaviour of Zircaloy-4 tube used as the fuel rod cladding in PWR nuclear power plants has been investigated at the different test environment, in light water and in air as a function of slip amplitude, normal load, test duration and frequency. Zircaloy-4 tubes were used for both of oscillating and stationary specimens. A fretting wear tester was designed to be suitable for this fretting test. The wear volume and specific wear rate of Zircaloy-4 tube in water were greater than those in air under various slip amplitude. It was found that delaminate debris and surface cracks were observed at low slip amplitude and high load in water Experimental results showed that the light water accelerated the wear of Zircaloy-4 tube at low slip amplitude in fretting.

• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.21-49
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• 2016

Many mechanical, electrical and electronic products have more than one performance characteristics (PCs). For example the performance degradation of rubidium discharge lamps can be characterized by the rubidium consumption or the decreasing intensity the lamp. The product may degrade due to all the PCs which may be independent or dependent. This paper deals with the design of optimal bivariate step-stress partially accelerated degradation test (PADT) with degradation paths modelled by gamma process. The dependency between PCs has been modelled through Frank copula function. In partial step-stress loading, the unit is tested at usual stress for some time, and then the stress is accelerated. This helps in preventing over-stressing of the test specimens. Failure occurs when the performance characteristic crosses the critical value the first time. Under the constraint of total experimental cost, the optimal test duration and the optimal number of inspections at each intermediate stress level are obtained using variance optimality criterion.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.5
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• pp.251-259
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• 2020

Ad hoc On-demand Distance Vector (AODV) protocol and its variants employ two important timers, hello and hold timer to keep track of topology changes. Moreover, hold timer is computed by multiplying constant value to hello timer. But, this configuration leads to inaccurate settings of hold timer. To solve this problem, in this paper, we propose a new dynamic adjustment of hello and hold timer scheme by removing dependency between them. A new metric to measure mobility is applied into hello timer, while expected link lifetime does holder timer. Simulation results show a significant reduction in the number of messages, a fact suggesting that it is possible to maintain and in some cases improve the performance of AODV with a minimum amount of messages released into the network.

• Journal of The Korean Dental Society of Anesthesiology
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• v.8 no.2
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• pp.127-127
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• 2008

Recently combining regimen of minimal doses of chloral hydrate, hydroxyzine and midazolam is good in sedation of children. Midazoalm, water soluble benzdiazepine, has rapid onset and relatively short duration of action. And midazolam has prospective amnesic effect. With these advantages midazolam is popular in conscious sedation for children. This study was to reveal the dose-dependency of behavior and physiologic effects of submucosal midazolam. Sedation records were surveyed retrospectively, of which the patients admitted from April, 2005 to July, 2007. we assigned three groups according the dose of midazolam, 0.1 mg/kg, 0.2 mg/kg and 0.3 mg/kg, respectively and the behavioral evaluation was analyzed with Houpt scale statistically. Combined submucosal midazolam increased the success rate in sedation and the vital signs were stable during sedation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.191-199
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• 2000

Since a few decade ago, there has been a demand on the safety monitoring of civil infrastructures, such as bridges, in order to prevent possibly occurrable disaster due to human negligence. The main cause for a failure or collapse of structures is absolutely a structural crack. For the reason, it is necessary to monitor the propagation of a structural crack. But a crack in bridges is gradually propagating with the traffic loads through the long term. There are lots of sensors to monitor structural cracks on bridges, but much information about them was not given so far. Therefore, in this study, the experimental comparison for long-term monitoring sensors, especially, strain measurement sensors, in terms of duration, temperature dependency, accuracy was made extensively.

• Steel and Composite Structures
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• v.46 no.2
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• pp.195-202
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• 2023

Dynamic deflection analysis of sandwich beams with cellular core under thermal and pulse loads has been performed in the present article. The cellular core sandwich beam has two layers fortified by graphene oxide powder (GOP) which are micromechanically modeled by Halpin-Tsai formulation. The pulse load has blast type and is applied on the top side of sandwich beam. The system of equations has been developed based on higher-order beam theory and Ritz method. Then, they are solved in Laplace domain to derive the dynamic deflections. The dependency of beam deflection on temperature variation, GOP content, pulse load duration/location and core relative density has been studied in detail.

• Korean Journal of Adult Nursing
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• v.15 no.4
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• pp.650-659
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• 2003

Purpose: The purpose of this study was to identify predictors of depression and quality of life among older adults with osteoarthritis. The predictors included in the model were the client's characteristics(age, pain, disease duration, ADLs), personal resources(hardiness, self-care agency and family support), and depression. Method: 150 subjects who were older than 65 years and had diagnosis of osteoarthritis participated in the study. To answer the research questions, descriptive analysis, Pearson correlation, and hierarchical multiple regression were utilized using SPSS WIN program. Result: Older adults who were younger and had lower levels of pain and dependency on ADLs, and higher levels of self care agency and hardiness reported lower levels of depression($R^2=0.517$). Older adults who had lower levels of depression, pain, and dependency on ADLs, higher levels of family support and hardiness, and who are younger reported higher levels of quality of life($R^2=0.084$). Conclusion: Based on the findings of this study, development of nursing intervention program including pain reduction, enhancing ADL abilities and personal resources (hardiness, family support) can be suggested. Further study is needed to increase the ability of generalization of the study findings to the broader population.

• Research in Community and Public Health Nursing
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• v.16 no.4
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• pp.517-526
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• 2005

Purpose: The purpose of this study is to find taxi drivers' smoking behavior, self-efficacy and expectation level of success in smoking cessation. It will provide useful information for developing nursing interventions in health promotion programs. Method: The subjects of this study were 271 taxi drivers in Seoul and its metropolitan area. Data were collected using a self-reported questionnaire asking smoking history, smoking behaviors, health problem, stages of change for smoking cessation, self-efficacy and the expectation level of success in smoking cessation. Data were analyzed through descriptive statistics. Pearson's correlation, Mann-Whitney U test, Kruskal-Wallis test and Cronbach's a. Results: Of the taxi drivers, 83.8% were current smokers. Stages of change were as follows: 45.8% were in the precontemplation stage, 26.2% in the contemplation stage, 13.7% in the maintenance stage, 12.2% in the preparation stage and 1.5% in the action stage. In addition. 20.3% of the subjects reported health problems such as hypertension, heart disease, diabetes mellitus and respiratory disease. The expectation level of success in smoking cessation was positively related with self-efficacy. There were statistically significant differences in the expectation level of success in smoking cessation according to the number of cigarettes per day and nicotine dependency. In addition. there were statistically significant differences in self-efficacy according to the number of cigarettes per day, duration of smoking (years) and nicotine dependency. Conclusion: The results of this study suggest that taxi drivers' health problems and smoking rate were serious. Therefore more systematic health promotion programs for smoking cessation should be developed and executed by health care specialists at individual taxi companies.

• Research in Community and Public Health Nursing
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• v.20 no.2
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• pp.251-258
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• 2009

Purpose: The study aimed to compare characteristics associated with smoking and smoking cessation of those who had succeeded in smoking cessation. Methods: Data were collected from January to June, 2008. The subjects were 9,819 smokers who were registered at the smoking cessation clinic of public health centers in Incheon. Four characteristics (demographic, health promotion, smoking, smoking cessation) were compared between 6-week (short-term) and 6-month (long-term) success groups. Results: There was a significant difference between the 6-week and 6-month success groups for smoking cessation in demographic characteristics (gender, age, job, social security), health promotion (BMI, alcohol dependency, BP), smoking (first smoking age, smoking duration, expiration CO concentration, nicotine dependency), and smoking cessation (attempt to quit smoking, reason for smoking cessation, information source for registration). Conclusion: The group of short-term smoking cessation success was younger than the other. Also, short-term success group was of lower socioeconomic class than the other. The 6-month success group had a larger number of attempts to quit smoking. Therefore, smoking cessation policy should be focused more on younger people and those in lower socioeconomic status. These groups should be given advice on smoking cessation motives and more frequent counseling for smoking cessation.

• Korean Journal of Acupuncture
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• v.27 no.4
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• pp.35-47
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• 2010

Objectives : To characterize the thermal properties of traditional warm needle and new warm needle with various air flows as an important environmental factor and to suggest the necessity of maintaining suitable environment of clinics to maximize their efficacy. Methods : We measured the temperature characteristics of traditional moxa warm needle and new moxa charcoal warm needle by applying an automatic temperature acquisition system with thermocouples while external various air flows were supplied. Temperatures of two positions at the needle body were measured while a moxa cone burned. Typical temperature characteristics like peak temperature, duration, curve shape and the efficiency of the heat stimuli by heat amount analysis were executed. Results : Both warm needles showed similar temperature curve with an increase in the air flow. Peak temperature and duration of effective heat decreased with the air flow, as shown in indirect moxibustion on garlic. The temperature change pattern by the air flow became more apparent when the total combustion heat was compared with the effective heat. The values from two positions on the needle body were significantly different, showing a distance dependency from the heat source of warm needle acupuncture. Conclusions : Thermal properties of warm needle acupuncture was observed variously with surrounding air flow of 0.0 - 0.7 m/s. It emphasized the importance of environmental control as well as the warm needle itself such as heat source and needle. The latter has already been known to deliver designated heat to subjects. It also indicated the importance of education and skill of the practitioners of warm needle acupuncture.