• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.43-52
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• 2001

Condition monitoring plays a vital role since it sustains the reliable operation of industrial plant and machinery in the pursuit of economic whole life operation. In order to achieve this goal, it is needed to monitor various parameters of mechanical system such as vibration, wear, temperature, and etc., and finally to diagnosis the root causes of any possible abnormal machine condition. In this work, we constructed a rotor system where various types of functional machine failures occurred frequently in industry were induced. Characteristics of the machine failure were monitored simultaneously by the on-line measurement of vibration, wear and temperature. Result showed that these parameters responded differently to the induced functional machine failure. The availability of each parameter on effective condition monitoring was discussed in this work.

• Tribology and Lubricants
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• 제35권5호
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• pp.317-322
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• 2019

In spite of progress in tribological research, machine component failure due to friction and wear has been reported frequently. This failure may lead to secondary damage that can cause huge expense for maintenance and repair. To prevent economic loss, it is important to detect and predict the initial failure point. In this sense, various researchers have been tried to develop Condition Monitoring (CM) method using Acoustic Emission (AE) generated while the materials undergo failure. In this study, effect of particles on friction and wear was investigated using the pin-on-plate friction test and AE signal was recorded with a band-width type AE sensor. The experiments were performed in dry and lubricant conditions using steel and glass as specimens. After the experiment, 3D laser microscope image was captured to evaluate the wear behavior quantitatively. The AE signal was analyzed in time-domain and frequency-domain. The amplitude was compared with the frictional results. The results of this study showed that particle generation accelerate wear, generate high magnitude AE signal and change the frequency characteristics of the signal. Also, lubricant condition test results showed low coefficient of friction, low wear rate, and low magnitude of AE signal compared to the dry condition. It is expected that the results of this study will aid in better assessment of wear in CM technology

• 한국가시화정보학회지
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• 제19권1호
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• pp.62-67
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• 2021

Selective catalytic reduction(SCR) is an exhaust gas reduction device to remove nitro oxides (NOx). SCR operation of ship can be controlled through valves for minimizing economic loss from SCR. Valve in SCR-high pressure (HP) system is directly connected to engine exhaust and operates in high temperature and high pressure. Long-term thermal deformation induced by engine heat weakens the sealing of the valve, which can lead to unexpected failures during ship sailing. In order to prevent the unexpected failures due to long-term valve thermal deformation, a failure prediction system using autoregressive integrated moving average (ARIMA) was proposed. Based on the heating experiment, virtual data mimicking temperature range around the SCR-HP valve were produced. By detecting abnormal temperature rise and fall based on the short-term ARIMA prediction, an algorithm determines whether present temperature data is required for failure prediction. The signal processed by the data collection algorithm was interpolated for the failure prediction. By comparing mean average error (MAE) and root mean square error (RMSE), ARIMA model and suitable prediction instant were determined.

• Geomechanics and Engineering
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• 제17권1호
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• pp.109-118
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• 2019

The movement of soil along a slope during rainfall can cause serious economic damage and can jeopardize human life. Accordingly, predicting slope stability during rainfall is a major issue in geotechnical engineering. Due to rainwater penetrating the soil, the negative pore water pressure will decrease, in turn causing a loss of shear strength in the soil and ultimately slope failure. More seriously, many constructions such as houses and transmission towers built in/on slopes are at risk when the slopes fail. In this study, the numerical simulation using 2D finite difference program, which can solve a fully coupled hydromechanical problems, was used to evaluate the effects of soil properties, rainfall conditions, and the location of a foundation on the slope instability and slope failure mechanisms during rainfall. A slope with a transmission tower located in Namyangju, South Korea was analyzed in this study. The results showed that the correlation between permeability and rainfall intensity had an important role in changing the pore water pressure via controlling the infiltrated rainwater. The foundation of the transmission tower was stable during rainfall because the slope failure was estimated to occur at the toe of the slope, and did not go through the foundation.

• 한국농공학회지
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• 제28권2호
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• pp.63-73
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• 1986

The model was developed by applying the principles of Bacot and Vidal to measure the behavior of deformation of the reinforced earth wall, and various tasts were performed by using the plastic fabric filter and the galvanized steel plate as a strip. The results obtained are as follows; 1. When the reinforced earth wall is deformed by the load, the strip is completely reinforced by the backfill materials and changed to the rigid block state, under the state of failure which permits sliding only, the next theoretical equation is formed. (H/L) . tan$\theta$ [cosO-sinOtanO] =2sinO[tan($\theta$ +0) +tanO] 2.The degree of the mutual reinforcement of the backfill material and the strip depend on the physical characteristics of the each material especially the angle of shearing resistance of the backfill material is desirable over 20$^{\circ}$ and, if it is over 400, its function could be a maximum. 3.The distribution of the maximum tensile strain of the reinforcement is changing with the height of reinforced earth wall, and when the height from bottom of the reinforced earth wall is 1.85 to 3. 35m, the maximum tensile strain appears at 2m from the skin element. The maximum tensile strain is increased by the depth of the reinforced earth wall from surface, and increased with the lapse of time after construction. 4.The failure surface of the reinforced earth wall by the concrete skin was about 60$^{\circ}$and the failure behavior of the reinforced earth wall in which the fabric filter was buried was slow, and so the pore pressure could be decreased. 5.It is possible to construct the fabric retained earth wall by the plastic fabric filter only. And the reinforcing effect between the steel plate and the plastic fabric filter is not largely different. however, in the aspect of the economic durability, the plastic fabric filter is more advantageous. 6.The reinforcing action mainly depends on the width and the length of the reinforcing materials, if possible, the full width is advantageous to enlarge the contact area with backfill. but considering the economic aspect, it is neccessary to develop the method controlling the space of the strip.

• 한국항만경제학회지
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• 제28권4호
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• pp.169-191
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• 2012

본 연구의 목적은 물류기업의 서비스실패시 물류서비스 제공기업의 조직특성과 인적특성이 서비스회복만족에 미치는 영향을 분석하고 서비스회복에 대한 만족이 고객의 신뢰와 관계몰입에 미치는 영향을 분석함으로써 물류서비스 제공자와 수요자간의 장기적 관계형성 및 유지전략을 제시하는 것이다. 본 연구의 목적을 달성하기 위하여 서비스실패와 회복 그리고 물류서비스의 특성에 관한 문헌연구와 함께 실증연구를 병행하였다. 실증연구는 대부분의 물류서비스기업이 서비스제공자이면서 수요자인 역할을 담당하고 있는 것을 감안하여 물류기업 종사자들을 표본으로 선정하였고, 설문지법을 이용하여 진행하였다. 인터넷과 직접방문, 우편접수 등을 통해 수집된 자료를 신뢰성과 타당성 검정을 실시하고 다중회귀분석방법을 이용하여 가설을 검정하였다. 연구결과 물류서비스 제공기업의 서비스회복을 위한 조직특성과 인적특성은 서비스 실패에 대한 회복만족에 정(+)의 영향을 미치는 것으로 나타났고, 회복만족은 고객의 신뢰와 관계몰입에 정(+)의 영향을 미치는 것으로 분석되었다

• 한국항만경제학회지
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• 제39권1호
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• pp.47-63
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• 2023

스마트 항만 및 항만 자동화에 수직 배치형 컨테이너 터미널을 적용하여 운영하는 사례가 늘고 있다. 본 연구는 수평 배치형과 수직 배치형 컨테이너 터미널에서의 본선작업 시간을 분석함으로써 각 터미널간 생산성을 비교하고, 향후 수직 배치형 컨테이너 터미널의 운영 효율성 증대 방안을 제시하고자 한다. 이를 위해 각각을 대표하는 터미널을 선정하여, 2018년부터 2022년까지 최근 5년 선석배정현황 데이터를 수집하였으며, 모수적 생존분석 기법인 가속실패시간모형(Accelerated Failure Time, AFT)을 활용하여 분석을 실시하였다. C/C 작업 조건이 '동일하다'는 가정 하에서, 수직 배치형 컨테이너 터미널에서의 본선 작업 생산성이 보다 좋은 것으로 나타났으며, 코로나19 기간에는 생산성이 감소한 결과를 나타냈다. 작업량이 많은 선박의 경우와 유럽 선사의 선박의 경우, 본선작업 시간이 감소하는 걸 알 수 있다. 적정 C/C의 투입 및 효율적 운영, 장비들 간 원활한 운영, shifting 작업은 증가, C/C를 포함한 하역 장비들의 준비시간 감소 및 고장/사고 최소화 등 수직 형태 컨테이너 터미널의 생산성을 높이기 위한 방안을 제시하였다.

• 임상간호연구
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• 제22권1호
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• pp.28-37
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• 2016

Purpose: This study was to investigate the relationships between among health literacy, knowledge and self-care behavior in elderly patients with heart failure(HF). Methods: 166 patients (age ${\geq}65$ years) with HF were recruited in a cardiovascular center of an university affiliated hospital. The structured questionnaire included Health literacy, Dutch Heart Failure Knowledge Scale, European Heart Failure Self-care Behavior, Self-Care of Heart Failure Index. Data were analyzed by descriptive statistics, Chi-test, Pearson correlation analysis, t-test and ANCOVA using SPSS/WIN version 21.0. Results: Participants with the high level of health literacy were more likely to be younger (p=.001), men (p=.001), with more education (p<.001), and have a job (p=.004), and with a higher economic status (p=.005). The positive correlations between the level of health literacy, knowledge, and self-care behavior were confirmed (p<.001). Participants with the high level of health literacy showed higher level of knowledge, more self-care behavior for health maintenance, and confidence. Conclusion: This study shows that the level of health literacy may influence knowledge and self-care behavior in elderly patients with HF. In order to improve self-care behaviors in elderly patients, a strategic nursing approach based on the level of patients' health literacy needs to be considered.

• 대한기계학회논문집A
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• 제34권9호
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• pp.1325-1330
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• 2010

터빈설비 각 중요부품의 고장은 발전정지라는 큰 파급효과를 유발하며, 예기치 못한 고장으로 설비의 이용률이 감소하게 되면 막대한 경제적 손실이 발생한다. 현재 발전설비는 제작사에서 제시한 정비주기를 기준으로 보수적인 예방정비를 실시하고 있으나, 급변하는 경영환경에서 경쟁력을 유지하기 위해서는 신뢰도를 유지하면서 정비비용을 절감하는 신뢰도 기반 정비방법을 도입 해야 할 필요가 있다. 신뢰성 있는 정비주기를 선정하기 위해서는 설비의 고장이력에 대한 면밀한 분석을 통하여 고장확률을 예측해야 한다. 본 논문은 발전설비 중 터빈 각 부품들의 고장이력을 데이터베이스로 만들고, Weibull 함수를 이용하여 최적의 정비시점을 예측하며, 정비주기를 결정하는 방법에 대하여 연구하였다.

• 지역연구
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• 제10권1호
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• pp.89-104
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• 1994

Recently, environmental issues have remained high on the agendas of public discussion and economic research. In the case of Korea, democratic movement in the late 80's centered people's concerns on the environmental dispute according to landfill, correctional institution, crematory, and nuclear powerplant, etc., Moreover, the failure to provide these kinds of facilities in time have caused serious social problems associated with environmental protection and economic development. The purposes of this paper are threefolds. First, they organize foreign and domestic NIMBYS case studies which have been settled in a desirable way. The second concern is to analyze the consciousness of NIMBYS resident by making up a questionnaire. Third, they estimate the market values of urban unwanted facilities by employing CVM(Contingent Valuation Method) procedure. The results of the study have a double implication : that NIMBYS resident are reluctant to accept government mechanical compensation based on simple published land values, and that unique concensus to preserve the viability and healthfulness of our environment among three main bodies: residents, people, government is necessary in solving NIMBYS subjects in Korea. In addition, this first implication develops to emphasize the intrduction of releveant measures taken to reconcile NIMBYS disagreement, which are complete openness of government policies, full support of local economic development, and perfect management of pollution protection systems for NIMBYS facilities.