• 한국산학기술학회논문지
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• 제19권6호
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• pp.567-574
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• 2018

위험 관리는 1) 체계개발 프로젝트의 비용, 일정 및 목표 성능 달성에 부정적인 영향을 줄 수 있는 위험 요소를 식별하고, 2) 식별된 각 위험 요소에 영향도와 발생 가능성을 부여하고 이를 바탕으로 식별 위험 요소를 관리하는 방법을 의미한다. 위험 요소를 사전에 식별하고 이에 대처함으로써 프로젝트의 비용 및 일정 관리와 목표 성능을 효과적으로 수행하고 달성할 수 있기 때문에 다양한 분야에서 위험 관리를 적용하고 있으며 이에 대한 많은 연구가 현재 진행되고 있다. 본 논문에서는 칼만 필터를 이용한 위험 요소 영향도 추정 방안을 제시한다. 위험 요소 영향도는 위험 발생 시의 손실 비용 및 일정을 변수로 갖는 식으로 표현된다고 가정하였다. 위험 요소 영향도의 참 값과 추정 값 사이의 오차를 줄이기 위한 방안으로서 선형 칼만 필터가 사용되었으며, 결과적으로 이를 통해 위험 관리 절차에 투입되는 자원을 절약할 수 있다. 제시된 위험 요소 영향도 추정 프로세스 검증은 시뮬레이션을 통해 수행되었다.

• 한국물환경학회지
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• 제32권1호
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• pp.70-79
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• 2016

Based on the soil moisture data assimilation suggested in the first paper (I), we estimated root zone soil moisture and evaluated drought severity using remotely sensed (RS) data. We tested the impacts of various spatial resolutions on soil moisture variations, and the model outputs showed that resolutions of more than 2-3 km resulted in over-/under-estimation of soil moisture values. Thus, we derived the 2 km resolution-scaled soil moisture dynamics and assessed the drought severity at the study sites (Chungmi-cheon sites 1 and 2) based on the estimated soil/root parameters and weather forcings. The drought indices at the sites were affected mainly by precipitation during the spring season, while both the precipitation and land surface characteristics influence the spatial distribution of drought during the rainy season. Also, the drought severity showed a periodic cycle, but additional research on drought cycles should be conducted using long-term historical data. Our proposed approach enabled estimation of daily root zone soil moisture dynamics and evaluation of drought severity at various spatial scales using MODIS data. Thus, this approach will facilitate efficient management of water resources.

• 간호행정학회지
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• 제14권2호
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• pp.118-130
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• 2008

Purpose: The purpose of this study was to estimate of home-visiting nursing costs for low-income elderly with chronic disease in a metropolitan city using the severity classification and ABC(active-based costing). Methods: First, the HHC activity pool was established. The performance time of each nursing activity were estimated. Second, nursing resources(labor costs, operating costs, and traffic expenses) were analyzed and nursing cost per minute was calculated. And then the cost of each activity was estimated. Third, 202 visiting cases were classified into three group by their severity. And then nursing cost per visit according to their severity was estimated. Results: 59 nursing activities were included in HHC activity pool. The average working time of 59 nursing activity was 6.7minutes and nursing cost per minute was 489 won. According severity, nursing cost per visit were in class I, 54,296 (won), class II 83,124(won), and class III 93,455(won).

• 한국방재학회 논문집
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• 제9권6호
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• pp.125-131
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• 2009

본 연구의 목적은 Bhaskar 등(2000)의 연구를 우리나라 유역에 적용하여, 홍수사상에 따른 유출수문곡선의 특성을 이용한 돌발홍수지수를 산정함으로써 돌발홍수의 심각성 정도를 정량화하고자 하였다. 또한, Bhaskar 등(2000)의 연구내용을 보다 확장하여 돌발홍수지수와 강우강도, 강우지속시간 및 총유출량과의 상관관계를 정량적으로 분석하였다. 본 연구에서는 미계측유역인 매곡천 유역의 과거 31개의 호우사상에 대한 돌발홍수의 상대심도를 파악하기 위해, 강우-유출모의를 통한 홍수수문곡선을 모의하고 이에 따른 돌발홍수지수를 산정하여 돌발홍수심도를 정량화하였다.

• Journal of Oral Medicine and Pain
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• 제33권3호
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• pp.269-277
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• 2008

본 연구는 측두하악장애 환자에서 이갈이의 유무 및 심도에 따른 추정연령과 실제 연령과의 차이(추정오차)를 평가하여 그 관계를 살펴보고, 측두하악장애 환자의 이갈이가 치아 교모도를 통한 연령감정에 미치는 영향에 대해 알아보고자 하였다. 교모도를 이용한 Takei의 연령감정법을 163명(대조군: 56명, 환자군: 107명)의 대상자에게 적용하였다. 저자는 추정연령과 실제연령의 차이를 통해 대상자의 교모도를 분석하여 다음과 같은 결론을 얻었다. 1. 연령에 따라서는 측두하악장애 환자군이 대조군에 비해 모든 연령군에서 교모도가 더 큰 경향을 나타냈으며, 특히 20대에서 유의성 있는 차이가 나타났다. 2. 성별에 따라서는 측두하악장애 환자군이 대조군에 비해 교모도가 더 큰 경향을 나타냈으며, 특히 남성에서 유의성 있는 차이가 나타났다. 3. 이갈이가 있는 측두하악장애 환자군은 대조군에 비해 교모도가 더 큰 경향을 나타냈으며 유의성 있는 차이를 나타냈다. 4. 측두하악장애 환자군간에는 이갈이 심도와 교모도에 대한 유의성 있는 상관관계를 발견하지 못하였다. 5. Takei에 의한 방법은 한국에서 여전히 유용한 연령감정법으로 평가된다. 따라서 측두하악장애 환자에서 교모도를 이용한 연령감정의 경우, 이갈이 심도에 대한 평가와 연령, 성별, 지역에 따른 차이에 대해서도 고려해야 할 것으로 생각된다.

• 한국안전학회지
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• 제15권2호
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• pp.118-125
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• 2000

Construction industry has one of the worst occupational health and safety records amongst all other industries. In this study, we developed a method to compute the severity rate (SR) and measured SR values of apartment construction incidents. The two-year records (1996-1997) from database by the Korea Industrial Safety Corporation (KISCO) were used in the current study. To determine the severity rate (SR), the lost workdays (LW) and the number of injured workers and fatalities (NIW) as well as the number of accidents (NA) were considered. These results appear to indicate that the SR measurement we developed in this study is adequate to estimate the safety of apartment construction environment.

• Journal of Ship and Ocean Technology
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• 제3권3호
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• pp.1-12
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• 1999

Spectral fatigue damage calculations has been performed on four ships in order to assess the effect that the probabilistic modeling of sea states has on the estimated fatigue life. The damage estimation method is based on the Miner- Palmgren fatigue damage formulation and a spectral approach is used to determine the necessary variances of the stress processes. Both the horizontal and vertical hull girder bending induced stress process together with the local water pressure induced stress process is taken into account. The wave scatter diagrams are applied in the calculations and their fatigue severity is assessed by analyzing the results obtained with the ten scatter diagrams and the four ships. All four ships are analyzed both in full load and ballast conditions and while traveling at both full and reduced speed. It is found that the fatigue severity of a wave scatter diagram is dependent on several parameters, some of these being the extreme wave hight extrapolated from the scatter diagram and the mean zero up-crossing period in conjunction with the ship length . Based on these three parameters and expression is derived in order to calculate one single number describing the fatigue severity of a scatter diagram with respect to a certain ship.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.951-960
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• 2016

Tower insulators in electric power transmission network play a crucial role in preserving the reliability of the system. Electrical utilities frequently face the problem of flashover of insulators due to pollution deposition on their surface. Several research works based on leakage current (LC) measurement has been already carried out in developing diagnostic techniques for these insulators. Since the LC signal is highly intermittent in nature, estimation of pollution severity based on LC signal measurement over a short period of time will not produce accurate results. Reports on the measurement and analysis of LC signals over a long period of time is scanty. This paper attempts to use Random Forest (RF) classifier, which produces accurate results on large data bases, to analyze the pollution severity of high voltage tower insulators. Leakage current characteristics over a long period of time were measured in the laboratory on porcelain insulator. Pollution experiments were conducted at 11 kV AC voltage. Time domain analysis and wavelet transform technique were used to extract both basic features and histogram features of the LC signal. RF model was trained and tested with a variety of LC signals measured over a lengthy period of time and it is noticed that the proposed RF model based pollution severity classifier is efficient and will be helpful to electrical utilities for real time implementation.

• Journal of Forest and Environmental Science
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• 제36권2호
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• pp.143-155
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• 2020

A juniper pocket rot fungus, Pyrofomes demidoffii is a basidiomycetous fungus responsible for damage of living Juniperus spp. However, its effect on the residual strength and on the extent of decay of juniper's trunk was not determined in any prior studies. The purpose of this study was to study the features of J. procera infected by P. demdoffii, and to estimate the level of strength loss and decay severity in the trunk at D.B.H height using different five formulas. Infected juniper stands were examined in two Ethiopian forests through Visual Tree Assessment (VTA) followed by a slight destructive drilling of the trunk at D.B.H height. The decayed juniper tree is characterized by partially degraded lignin material at incipient stage of decay to completely degraded lignin material at final stage of decay. In the evaluated formulas, results of ANOVA showed that a significantly higher mean percentage of strength loss and decay severity were recorded in the trees of larger D.B.H categories (p<0.001). The strength loss formulas produced the same to similar patterns of sum of ranks of strength loss or decay severity in the trunk, but the differences varied significantly among D.B.H categories in Kruskal Wallis-test (p<0.001). In conclusion, the employed formulas showed similar to different degree of variability in quantification of strength loss or decay severity in the trunk. The findings of our study could be used as the baseline for further study on juniper's strength loss or decays in the trunk of Juniperus spp. and unequivocally helps to design the corresponding management as result of P. demidoffii.

• 산업경영시스템학회지
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• 제33권4호
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• pp.209-217
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• 2010

Reliability tools such as QFD and FMEA identify voice of customer related to product design, its use, how failures may occur, the severity of such failures, and the probability of the failure occurring. With these identified items, a development team can focus on the design process and the major issues facing the product in its potential use environment for the customer. The purpose of this research is to develop a reliability estimation process of agricultural machinery components using QFD, FMEA, and field failure data. Based on QFD method, customer requirements, engineering design elements and part characteristics were deployed. Using the field failure data, failures are investigated, and Weibull B10 life are estimated. This estimation process is useful for preparing the design input and planning the durability target.