• Journal of Advanced Marine Engineering and Technology
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• 제39권3호
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• pp.211-216
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• 2015

차체중량이 90 ton인 초대형 유압굴삭기에서는 유압시스템의 효율향상을 통한 연비개선을 위해서 유압펌프 구동용 기어박스(hydraulic pump driving gear box)를 사용하여 다수(3~6개)의 펌프를 병렬로 장착하여 사용한다. 펌프 구동 기어 박스는 굴삭기의 대형엔진과 연결되는 입력 축 1개로 기계적 동력인 회전수와 토크를 공급받아 고압펌프와 저압펌프에서로 다른 기계적 출력을 공급하게 된다. 따라서 펌프 구동 기어박스는 굴삭기의 대동맥과 같으며, 엔진이 가동되는 시간동안 지속적으로 펌프를 구동함으로서 장 수명이 요구된다. 본 연구에서는 큰 시험동력(600kw)이 요구되는 수명평가에서 에너지절감을 위한 전기 회생식 시험 장비를 구축하여 높은 에너지 절감과 수명시험을 수행하면서 기어박스의 마모 특성을 분석하는 방법으로 윤활유 오염 입자 분석과 기어파손 유무를 검증하는 방법으로 진동분석 방법을 사용하였다.

• 한국방재학회 논문집
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• 제10권1호
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• pp.15-22
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• 2010

자연환경 중 다양한 형태로 존재하는 염화물은 콘크리트 구조물의 철근 부식을 야기하며 이에 따른 심각한 내구성 저하와 함께 구조물의 수명을 감소시킨다. 현재 콘크리트 중의 염화물 침투 특성을 규명하기위한 연구는 해안가 장기 폭로 시험과 전기화학적 촉진 시험에 의한 확산계수 평가 등에 의해 지속적인 발전을 이루어왔으나 콘크리트의 배합, 수화도, 고정화능력, 공극률의 재료적 특성을 고려한 이성적이며 포괄적인 염화물 침투 모델에 관한 연구는 부족한 실정이다. 따라서 본 연구에서는 실내 염화물 침지 실험을 통해 콘크리트의 염화물 고정화 특성을 파악하고 이를 고려한 염화물 침투 모델로서 비정상상태의 염화물 침투 해석과 함께 해양침지환경하의 철근콘크리트 구조물의 내구수명 예측을 시도하였으며 SHRP 기준과 20~40%의 내구수명의 차이를 보였다.

• 근관절건강학회지
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• 제9권1호
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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.

• Tribology and Lubricants
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• 제24권4호
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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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• 제15권3호
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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.

• 비파괴검사학회지
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• 제20권1호
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• pp.18-26
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• 2000

화력발전소 보일러 고온배관인 주증기관, 헤드 및 증기드럼 등의 설비들은 장시간동안 고온고압의 가혹한 조건으로 운전됨에 따라 크리프손상에 의해 열화되고 있다. 이들 설비의 크리프손상측정에 적용되는 종래의 비파괴기법인 레프리카법, 전기저항법 및 경도법 등은 복잡한 측정절차 및 접근성, 검사결과의 신뢰도 및 측정정도 등 여러가지면에서 단점이 많다. 따라서 본 논문에서는 화력발전소 주요 고온배관에서 발생되는 경년열화인 크리프손상에 대한초음파 측정연구를 수행한 결과로서, 고온배관재료인 Cr-Mo강의 크리프 인공열화재를 대상으로 이들에 대한 크리프손상 상태별 초음과 음속(sound velocity) 및 감쇠(attenuation)의 초음파 신호특성을 평가하였다.

• 한국철도학회논문집
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• 제19권1호
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• pp.46-53
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• 2016

LED 광원은 기존 광원에 비해 수명이 길고 에너지 효율이 좋은 것으로 알려져 있다. 최근 철도차량의 고속화에 따른 전방시야 확보와 안전적인 운행을 고려하여 LED광원을 이용한 전조등이 증가하고 있다. 그러나 LED광원의 수명시험 데이터를 근거로 한 제품 수명 평가체계는 구동전류, 온도 및 진동 등 수명-스트레스 인자에 따라 다양한 수명특성을 보인다. LED제품은 주로 온도에 의해 예측된 수명에 미치지 못하는 경우가 일반적이므로 온도제어부의 성능평가는 수명시험 이전에 수행되어야 한다. 본 연구는 철도차량용 LED전조등의 수명시험 장치의 온도제어부 시작품을 제작하고 성능시험 결과를 바탕으로 타당성을 검증한다.

• 종양간호연구
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• 제1권1호
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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.

• 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.

• 콘크리트학회논문집
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• 제12권1호
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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.