• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.100-107
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• 2024

Currently, in Korea, due to the rapid aging and deterioration of facilities, the minimum Maintenance Level and Performance Level' of facilities are required by the 'Facility Safety Act' or 'Infrastructure Management Act'. Since infrastructure assets have a long lifespan and the pattern of deterioration over time is complex, it is very difficult to maintain infrastructure as 'minimum maintenance state' or 'minimum performance state' by the current way of management. 'Asset Management' shall be performed not only by a technical perspective, but also by an accounting perspective such as cost and asset value. However, due to lack of awareness of 'asset management' among stakeholder, only technical perspective management is being carried out in practice. In order to effectively manage infrastructure assets, complex consideration of various asset value factors such as budget and service as well as safety and durability are required. In this paper, we presented a theory to evaluate and quantify the road network value for efficient asset management of the road network. We also presented a method of simulation to apply the theory presented in this paper. Through simulation and the results derived from this study, it is possible to specify the budget for the future national asset management, and to optimize the strategy for the management of old road facilities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.1005-1012
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• 2014

Gears are critical elements in automobiles, and their use as power transmitting machine elements in engineering applications is quite extensive. In the areas of contact between gear teeth, the condition of a gear is likely to deteriorate due to contact fatigue, wear, material defects, lubrication failure, etc. Thus, it is necessary to monitor its condition to ensure smooth power transmission. Gear teeth deterioration causes failures such as abrasive wear, scuffing, pitting, and spalling. These failures lead to a higher level of vibration signals in the gear system. This paper presents the results of an experiment on the surface fatigue wear of a spur gear system. The correlation between the estimated specific film thickness, statistical parameter of the vibration signals, and Stribeck curve was considered in this study.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.457-461
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• 2007

Laser slide marking systems are being considered by the staffs of clinical laboratories in hospitals as the main potential substituent for the conventional manual processes of the laboratory works. Many of the processes in domestic hospitals such as operations of test equipments in clinical laboratories and physical distributions in hospitals are being computerized due to the recent development of information technologies. The clinical laboratories in charge of inspection processes are putting their efforts on the computerization and automation of the test equipments, which increases the demand for the usage of laser marking slide systems which is the main component of the inspection works. The domestic market size of the laser slide marking systems is expected to be 250 million won in 2008, which is believed to increase to 1.75 billion won in 2012. The laser slide marking system was first introduced to domestic hospitals in 2005. It's product life cycle is currently on the early stage, and it is believed to have a very high growth potential in the future.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.104-110
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• 2007

Temperature rise characteristics of medium voltage class transformers and dielectric characteristics of its insulation oil according to the loading rate were investigated using the transformer that has thermocouples embedded in the windings. The hottest-spot of the transformer locates at about 2/3 height of the windings where they adjoin each other among the 3 phase windings. The temperature difference between the hottest-spot and top-oil is about $17[^{\circ}C]$ and the value keeps uniformly in short time after changing the loading rate. Capacitance of the oil varies in inverse proportion to temperature and the inclination rate is about -0.0106 that is not dependent on the aging rate. On the other hand the capacitance is increased depending on the aging rate, so the capacitance characteristics of the oil could be applied to the diagnostic technique.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.87-97
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• 2020

This study summarized longevity factors of enterprises and presented longevity mechanism. By analogy of human aging and corporate longevity, the company's decline and longevity phenomenon were analyzed to derive corporate longevity mechanism, presented domestic and foreign longevity enterprises' cases study using above mechanism. The longevity mechanism first, as the human body restricts free radicals by dietary restrictions, companies also need continuous input efficiency. Second, as cognitive reserve by high thinking activities helps heath lifespan, companies can strengthen their profitability by continuous R&D. Third, as humans improve antioxidant functions by exercise, companies should develop risk management capabilities for environmental changes. This study can contribute to sustainable strategies for corporate managers, ultimately plan to suggest model of evaluation or diagnosis of corporate longevity.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.445-452
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• 2005

This paper presents a design method to minimize Life Cycle Cost (LCC) of steel box girders. The LCC considered in this paper includes initial cost, expected life-cycle maintenance cost and repair cost. A load carrying capacity curve is derived from a condition grade curve of steel girders and load tarrying capacity that is measured in safety diagnostic test. And then, optimal design of steel box girders is performed on the basis of load carrying capacity curve. In this paper time and number of times for repair of steel girders are determined based on the calculated load carrying capacity curve. Also, annual costs considering real discount rate are compared and analyzed in various cases. It is concluded that the optimal design of steel box gilders considering LCC by the presented method will lead to more economical and safer girders than conventional design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.613-619
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• 2016

A pneumatic control valve performs a major role in controlling the flow of a system or the level of a key tank in many power plants, and its performance should be guaranteed during the plant's lifetime. Its operation starts by supplying air to the pneumatic actuator or by exhausting the air from the actuator. To control the valve position, the amount of air supply or exhaust is adjusted by a control loop where various accessaries are equipped. In this paper, air leakage in the air supply line, changes in the valve packing force, and false adjustments of zero and the span of the positioner are simulated and analyzed using a 2-in pneumatic valve with a position control loop including an I/P converter and positioner, where the valve position is controlled within ${\pm}2%$ of the control pressure at 67% opening position.

• 대한근관절건강학회:학술대회논문집
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• 2002.11a
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• pp.238-246
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• 2002

최근 경제의 발전과 의학의 발달로 인하여 인간의 수명은 점차 연장됨에 따라, 노인인구도 급격히 증가하고 있다. 40세 이상 여성 인구도 8.998천명으로 전체 여성의 38%를 차지하며 이는 매년 증가할 것이다. 그리하여 전체 인구에 대한 폐경 여성의 점유율도 급격히 증가하고 있다. 폐경 이후 $5{\sim}10$년 동안 매년 $2{\sim}4%$씩 골농도가 감소하고 있기 때문에 폐경기 여성을 위협하는 주요 질환 중 하나가 골다공증이다. 하지만 골다공증은 뚜렷한 자각증상이 없어 골 기형 및 골절이 발생하기 전에는 조기발견이 어렵다. 골다공증은 모든 중년 여성의 건강문제이므로 지역사회에서 골절 발생 위험율을 줄일 수 있도록 골다공증 예방을 위한 건강관리가 필요하다. 본 연구의 목적은 지역사회에서 적용할 수 있는 골다공증 예방 프로그램을 개발하여 그 효과를 검정한 후 지역사회 중년 여성 건강증진 프로그램으로 활용코저 함에 있다. 골다공증 예방 프로그램은 운동과 교육으로 구성하였으며, 12주 동안 점핑 동작 위주의 에어로빅과 스텝퍼 운동과 근력강화운동(최대 심박수의 $70%{\sim}80%$, $70{\sim}80$분, 3회/주)을 병행하여 실시하였고, 교육은 운동과 칼슘 섭취의 중요성을 건강 신념 이론에 근거하여 자기 효능감을 증대시키는 교육을 하여 지속적인 운동 실천과 칼슘식이 섭취를 하도록 하였다. 대상자는 서울시 일개 보건소에서 골감소증으로 진단받은 폐경 여성으로 실험군 19명과 대조군 19명이었다. 골다공증 예방 프로그램의 효과는 골밀도, DPD ratio, osteocalcin, 일일 평균 칼슘섭취량, 일일 열량 소모량, 배근력, 최대 산소 섭취량, 제지방량과 건강신념 변수로 측정하였다. 수집된 자료는 PC SPSS 8.0 프로그램을 이용하여 대상자의 일반적 특성은 실수와 백분율로 실험군과 대조군의 동질성 검사는 t-test, $x^2-test$ 및 Fisher exact test를 이용하였고, 두 집단 간 결과변수들의 중재 전후의 차이는 t-test로 분석하였다. 연구 결과는 다음과 같다. 1) $L_{2-4}$ 골밀도는 실험군이 대조군에 비하여 유의하게 높았다. 2) DPD ratio와 osteocalcin은 두 집단간 유의한 차이가 없었다. 3) 배근력은 실험군에서 대조군보다 유의하게 증가하였으나, 제지방량과 최대 산소 섭취량은 유의한 차이가 없었다.

• Journal of Aerospace System Engineering
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• v.14 no.spc
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• pp.31-38
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• 2020

The aircraft system safety assessment, which is emphasized in the development and certification of aircraft, is a systematic and comprehensive evaluation process to determine that all relevant failure conditions have been identified and that all significant combinations of failures cannot result in unacceptable hazards. As the aircraft systems become more complex and require integrated function and performance, proper safety objectives must be established and appropriate assessments are need to be accompanied. This paper has prepared to propose the efficient probabilistic analysis of failure data to evaluate the risk level over the entire aircraft lifecycle through the safety assessment and to review the considerations for aircraft certification and safety improvement.

• Journal of Korean Academy of Nursing
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• v.13 no.3
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• pp.127-144
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• 1983

오늘날은 과학문명의 발달로 인하여 기존지식의 수명이 점차 짧아져 가고있는 것이 특징이다. 지식의 증가는 단순히 지식의 양을 증가시키는 역할뿐 아니라 많은 기존지식을 불충분하고 쓸모 없는 것으로 바꿔버리게 한다. 그러므로 학교에서는 학생들에게 어떤 특정지식의 축척보다는 그 학문에 내재해 있는 기본적인 지식의 구조를 학습하게 하여 여러 가지 개념을 관련시키는 논리적 방법을 학습하게 하고 합리적인 탐구방법을 구사할 수 있도록 하여 변화하는 미지의 세계에 대처해 나갈 수 있도록 하는 것이 중요하다. 본 연구는 간호학의 기본 지식구조를 확인하는데 그 목적이 있다. 본 연구를 하게 된 동기는 간호업무의 근거로 활용도리 지식체계는 교육과정의 조직원리로 작용될 유형이나 구조를 지니고 있으며 이런 유형이나 구조를 중심으로 간호교육과정을 구성하는 것이 간호교육에 필수적이라는 문제에서 비롯되었다. 연구방법은 1982년 9월부터 1983년 5월에 걸쳐 간호학 문헌을 체계적으로 분석하여 간호학의 개념적 지식구조와 구문적 지식구조를 확인하였다. 그 결과 얻어진 결론은 다음과 같다. 1. 간호학의 개념적 구조： 모든 학문에는 탐구의 대상인 특수현상을 설명하고 서술하는데 활용되는 일련의 실질적, 개념적 구조를 가지고 있다. 그러나 그 학문의 중요한 부분 또는 중심을 포함하고 있는 개념들이 그 분야 또는 학문의 개략이라고 할 수 있는데 연구결과 간호학에서 가장 높은 순위의 대표적 특질을 지닌 개념은 인간, 건강, 환자/대상자, 간호, 행동으로 분석되었다. 2. 간호학의 구문적 지식구조 : 지식구조의 두 번째 요소인 학문의 구문(syntax)은 간호학에서의 특징적인 탐구방법과 관련되나 개념적 구조와 마찬가지로 탐구방법은 학문에 따라 다르며 그 분야의 주요양상을 나타낸다. 연구결과 간호학에서의 특징적인 탐구방법은 공동적으로 간호과정(nursing process)임이 나타났으며 그 요인으로는 사정, 진단, 계획, 수행, 평가의 다섯 단계로 분석되었다.