• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.211-216
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• 2015

Large hydraulic excavator weighted 90 tons used the several pumps installed in parallel to use the hydraulic pump driving gearbox to improve fuel consumption by improving the energy efficiency of the hydraulic system. Gearbox connected to hydraulic pump supply the mechanical output to the high pressure and low pressure pump to be supplied by torque and rotation, which are the mechanical power, through a input shaft connected to large size engine of the excavator. So, gearbox connected to hydraulic pump is same as main artery in the human body and is required long life because it operates the hydraulic pump continuously during operating the engine. This study had used oil contamination analysis method to check the wear characteristics of the gearbox and frequency response characteristic analysis method to check the failure of the teeth failures of gearbox, while the test equipment adopted by the electrical feedback method to reduce the energy consumption was operating for the life assessment, in which the required power was 600 kW input power.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.15-22
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• 2010

Chloride-induced corrosion of steel bars in concrete exposed to marine environments has become one of the major causes of deterioration in many important facilities made of reinforced concrete. A study on chloride penetration in concrete has developed through long period exposure test along seawater, assesment of chloride ion diffusion by electrochemical techniques and so on. However, reasonable and exclusive chloride penetration model considering concrete material properties with mixture, degree of hydration, binding capacity has not been established. Therefore, in this paper, chloride penetration analysis of non-steady state is accomplished with material properties of concrete. Comparing with the results of analysis and chloride ponding test, we could accept the effect of binding capacity on chloride penetration in concrete and these results could be applied to a service life prediction of R.C. structures submerged in seawater. Therefore, there are 20~40% differences of service life to SHRP prediction.

• Tribology and Lubricants
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• v.24 no.4
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• pp.179-185
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• 2008

Microporous polymer lubricants(MPLs) are solid polymer materials containing micropores which are filled with liquid lubricants, and which are molded or formed to suit rolling bearings or other machine parts requiring lubrication. MPLs can be effectively applied to provide long-term, maintenance-free lubrication of a variety of machine elements without fully replacing of oils and greases. The application of rolling bearings packed fully with an MPL could reduce or eliminate the problems such as grease deterioration, leakage, under-lubrication caused by insertion of water or foreign matters under severe operation conditions. This paper discuss the application of MPLs for lubrication of rolling ball bearings. Two different MPLs were synthesized and the features of MPLs were tested. Characteristics of the bearings which are packed fully with synthesized MPLs were investigated using SEM, TG/DSC, extents of oil leakage, OIT, and life time test. After these preliminary tests twelve MPLs were synthesized and evaluated by measuring extents of oil leakage and OIT values. Then synthesis conditions for the optimum MPL were selected by SSRED(Six Sigma Robust Engineering Design) pro gram using extents of oil leakage and OIT values respectively. The optimum MPL by means of OIT value showed higher performance such as long life time and application at higher temperature of $140^{\circ}C$ than previous temperature of $100^{\circ}C$.

• Smart Structures and Systems
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• v.15 no.3
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• pp.555-576
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• 2015

The large number of long-span bridges constructed in China motivates the applications of structural health monitoring (SHM) technology. Many bridges have been equipped with sophisticated SHM systems in the mainland of China and in Hong Kong of China. Recently, SHM technology has been extended to field test systems. In this view, SHM can serve as a tool to develop the methods of life-cycle performance design, evaluation, maintenance and management of bridges; to develop new structural analysis methods through validation and feedback from SHM results; and to understand the behavior of bridges under natural and man-made disasters, rapidly assess the damage and loss of structures over large regions after disasters, e.g., earthquake, typhoon, flood, etc. It is hoped that combining analytical methods, numerical simulation, small-scale tests and accelerated durability tests with SHM could become the main engine driving the development of bridge engineering. This paper demonstrates the above viewpoint.

• Journal of muscle and joint health
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• v.9 no.1
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• pp.40-52
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• 2002

This study was conducted to describe disease characteristics, psycho-social factors and treatment behavior of patients with lupus and to analyze relationships anions these variables. The subjects were consisted of 120 lupus patients at G university hospital in Seoul. Data were collected by means of structured interview with questionnaires, and analyzed by using frequencies, $x^2$test, t-test, ANOVA, and correlation. The results were as follows; 1. The average age of the subjects was 31.34 years and average duration of suffering lupus was about 7.3years. Severity of symptoms was moderate and the disturbance of living activities was at the very low level. 2. Self-efficacy score of lupus patients was high, and life satisfaction was at moderate level. 3. Dosage for most of the subjects was about twice a day. 16.7% of them took non-prescribed medicine and only 27.5% perform exercise. 4. Positive correlation was shown among symptom, discomfort of living activities, self-efficacy and life satisfaction, while there was negative correlation among symptom and self-efficacy, symptom and life satisfaction, discomfort of living activities and self-efficacy, and discomfort of living activities and life satisfaction. In addition, exercise showed significant relationship with discomfort of living activities, and non-prescribed medicine showed significant relationship with discomfort of living activities and self-efficacy. These results show that lupus is a chronic disease of long suffering duration among young people. Severity of the symptom was at modest level, while discomfort of living activities were relatively insignificant. However self-efficacy was relatively high. Furthermore self-efficacy has influences on symptom and discomfort of life activities, just as exercise affects discomfort of life activities. Therefore it is required to examine further measures for continuous exercise.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.1
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• pp.18-26
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• 2000

Boiler high-temperature pipelines such as main steam pipe, header and steam drum in fossil power plants are degraded by creep damage due to severe operating conditions such as high temperature and high pressure for an extended period time. Conventional measurement techniques(replica method, electric resistance method, and hardness test method) for measuring creep damage have such disadvantages as complex preparation and measurement procedures, too many control parameters. And also these techniques have low practicality and applied only to component surfaces with good accessibility. In this paper, artificial creep degradation test and ultrasonic measurement for their creep degraded specimens(Cr-Mo alloy steels) were carried out for the purpose of evaluation for creep damage. Absolute measuring method of quantitative ultrasonic measurement for material degradation was established, and long term creep degradation tests using life prediction formula were carried out. As a result of ultrasonic tests for crept specimens. we conformed that both the sound velocity decreased and attenuation coefficient linearly increased in proportion to the Increase of creep life fraction($\Phi$c).

• Journal of the Korean Society for Railway
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• v.19 no.1
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• pp.46-53
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• 2016

LED light sources have been known to have a long life and good energy efficiency compared to traditional light sources. Recently, headlamps using LED light sources have ensured the forward visibility and safe operation of high-speed rolling stock. However, assessing the lifespan of LED headlamps based on real test data is not easy because it depends on the multiple stress factors such as a fixed driving current, junction temperature, vibration and so on. Generally, LED headlamps have failed before their advertised life span mainly due to temperature. Thus, the performance assessment of a temperature control unit should be done before a life cycle test of LED headlamps. This study attempted to develop a prototype temperature control module for a lifecycle test system using a commercial LED headlight and verified the system through experiments.

• Asian Oncology Nursing
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• v.1 no.1
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• pp.5-17
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• 2001

It is known that aggressive treatment of chemotherapy, radiation and autogenous stem cell transplantation is effective for prevention of recurrence in the high-risk breast cancer patients. It was assumed that this procedure takes a longer time and decreases the quality of life more than the standard adjuvant chemotherapy. However, there are few studies comparing the quality of life of patients having bone marrow transplantation and adjuvant chemotherapy. Most of the studies were focused on the quality of life in one point of time, such as only during the early treatment stage, only overall quality of life rather than specific dimensions of the quality of life. The purposes of this study are 1) to identify the difference of the quality of life between two different treatment patterns, adjuvant chemotherapy and autogenous stem cell transplantation: 2) to identify the mostly affected dimension and the periods of time affected by the treatment patterns; and 3) to identify the trajectories of quality of life in each treatment pattern. This is a time series design that measures 4 different points of times. At the beginning of the study, 19 patients were placed in the chemotherapy group and 12 in the group of auto-peripheral blood stem cell transplantation. The inclusion criterion was the advanced disease stage of 3 or over with metastasis of more than 5 lymph nodes. The exclusion criteria were 1) anyone who has metastasis to other organ; 2) anyone who had psychological problems. Ferrell's Quality of Life Scale for Cancer Survivors 41 items on a 10 point scale was used. The QOL-CS includes 4 dimensions, which were labeled physical, psychological, social, and spiritual. The Cronbach‘s alpha of this scale was 0.89. Mann-Whitney U test and Friedman test were used to test each hypothesis. In comparison of the two groups, the quality of life of the bone marrow transplantation group dramatically increased at the 3rd and 6th month after transplantation, while the chemotherapy groups results stayed lower. The most affected dimension of the quality of life at the end of the treatment was the physical dimension. However, it and increased along with time, while the psychological dimension values remained low over the long-term period. Intensive nursing care is needed during the entire period of chemotherapy in all patients having chemotherapy, and is also required for right after cases of bone marrow transplantation.

• 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.

• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.33-44
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• 2000

Since the mechanism of chloride diffusion and its ratio in concrete depend on structural conditions and concrete as a micro-structure, if these are analyzed quantitatively, the long-term ageing of structures can be predicted. Although, a quantitative analysis of concrete micro-structure, in which the results are affected by various parameters, is very difficult, this can be done indirectly by the durability test of concrete. In this study, the compressive strength, void ratio and air permeability of concrete. In this study, the compressive strength, void ratio and air permeability of concrete are chosen as the parameters in concrete durability test, and these effects on test results are analysed according to changes of mixing properties. The relationships between parameters and chloride diffusion velocity is used for prediction models of chloride diffusion. The developed prediction models for the chloride diffusion according to mixing and physical properties, can be used to estimate the service life and corrosion initiation of reinforcing bars in marine structures.