• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.191-191
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• 2010

As many researchers want to predict or assess more about wind condition and wind power generation, CFD(Computational Fluid Dynamics) analysis method is very good way to do predict or assess wind condition and power generation. But CFD analysis is needed much knowledge of aerodynamics and physical fluid theory. In this paper, Auto-Wind CFD analysis program will be introduced. User does not need specific knowledge of CFD or fluid theory. This program just needs topographical data and wind data for initial condition. Then all of process is running automatically without any order of user. And this program gives for user to select and set initial condition for advanced solving CFD. At the last procedure of solving, Auto-Wind program shows analysis of topography and wind condition of target area. Moreover, Auto-Wind can predict wind power generation with calculation in the program. This Auto-Wind analysis program will be good tool for many wind power researchers in real field.

• 한국안전학회지
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• 제18권4호
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• pp.164-168
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• 2003

Bayes theorem, suggested by the British Mathematician Bayes (18th century), enables the prior estimate of the probability of an event under the condition given by a specific This theorem has been frequently used to revise the failure probability of a component or system. 2-Stage Bayesian procedure was firstly published by Shultis et al. (1981) and Kaplan (1983), and was further developed based on the studies of Hora & Iman (1990) Papazpgolou et al., Porn(1993). For a small observed failure number (below 12), the estimated reliability of a system or component is not reliable. In the case in which the reliability data of the corresponding system or component can be found in a generic reliability reference book, however, a reliable estimation of the failure probability can be realized by using Bayes theorem, which jointly makes use of the observed data (specific data) and the data found in reference book (generic data).

• 항공우주기술
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• 제9권1호
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• pp.93-97
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• 2010

액체산소/케로신을 사용하는 가스발생기 사이클 액체로켓엔진의 비추력 해석을 수행하였다. 본 해석 방법으로 재연한 300톤급 엔진의 시스템 성능은 문헌에 보고된 결과와 비교하여 비추력 0.1%, 최적 연소압 12%의 오차를 보였다. 오차의 주요 원인은 문헌에 공개되지 않은 서브시스템의 성능모델 차이와 가스발생기 생성물의 물성 모델 차이로 판단된다. 막냉각이 적용되는 30톤급 1단용 엔진의 경우, 연소압 68 bar에서 혼합비 2.2가 최적 비추력 조건인 것으로 평가되었으며 최적 조건은 주어진 성능 모델에 따라 달라질 수 있다.

• 지역사회간호학회지
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• 제29권4호
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• pp.520-529
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• 2018

Purpose: The purpose of this study is to identify factors influencing activities-specific balance confidence in community-dwelling older adults. Methods: This is secondary analysis of data from an intervention study for improving cognitive function. The data were collected from March 2 to September 30, 2017 at a senior center. Data of 131 older adults were included for this secondary analysis, and were analyzed by using t-test, ANOVA, and multiple regression. Results: The mean score of activities-specific balance confidence is 65.08 out of a possible range of 0-100. The significant factors affecting activities-specific balance confidence among old adults include 'more than 85 years old', 'waist circumference', 'depressive symptoms', 'activity restriction due to fear of falling', and 'self-rated health' which explained 52.8% of the variance. Conclusion: The study results indicate that psychologic factors as well as physical condition should be considered for interventions to increase activities-specific balance confidence.

• 한국소음진동공학회논문집
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• 제21권2호
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• pp.146-153
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• 2011

Model based machine condition diagnosis methods are generally using a normal and many failure models which need sufficient data to train the models. However, data, especially for failure modes of interest, is very hard to get in real applications. So their industrial applications are either severely limited or impossible when the failure models cannot be trained. In this paper, continuous hidden Markov model(CHMM) with only a normal model has been suggested as a very promising machine condition diagnosis method which can be easily used for industrial applications. Generally hidden Markov model also uses many pattern models to recognize specific patterns and the recognition results of CHMM show the likelihood trend of models. By observing this likelihood trend of a normal model, it is possible to detect failures. This method has been successively applied to arc weld defect diagnosis. The result shows CHMM's big potential as a machine condition monitoring method.

• Smart Structures and Systems
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• 제20권2호
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• pp.247-261
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• 2017

In the field of dynamic measurement and structural damage identification, it is generally known that modal frequencies may be measured with higher accuracy than mode shapes. However, the number of natural frequencies within a measurable range is limited. Accessing additional forms of modal frequencies is thus desirable. The present study is concerned about the extraction of artificial boundary condition (ABC) frequencies from modal testing. The ABC frequencies correspond to the natural frequencies of the structure with a perturbed boundary condition, but they can be extracted from processing the frequency response functions (FRF) measured in a specific configuration from the structure in its existing state without the need of actually altering the physical support condition. This paper presents a comprehensive experimental investigation into the measurability of the ABC frequencies from physical experiments. It covers the testing procedure through modal testing, the data processing and data analysis requirements, and the FRF matrix operations leading to the extraction of the ABC frequencies. Specific sources of measurement errors and their effects on the accuracy of the extracted ABC frequencies are scrutinised. The extracted ABC frequencies are subsequently applied in the damage identification in beams by means of finite element model updating. Results demonstrate that it is possible to extract the first few ABC frequencies from the modal testing for a variety of artificial boundary conditions incorporating one or two virtual pin supports, and the inclusion of ABC frequencies enables the identification of structural damages without the need to involve the mode shape information.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.193.1-193.1
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• 2010

Small hydropower resources for five major river systems have been studied. The model, which can predict flow duration characteristic of stream, was developed to analyze the variation of inflow caused from rainfall condition. And another model to predict hydrologic performance for small hydropower(SHP) plants is established. Monthly inflow data measured at Andong dam were analyzed. The predicted results from the developed models in this study showed that the data were in good agreement with measured results of long term inflow at Andong dam. It was found that the models developed in this study can be used to predict the available potential and technical potential of SHP sites effectively. Based on the models developed in this study, the hydrologic performance for small hydropower sites located in river systems have been analyzed. The results show that the hydrologic performance characteristics of SHP sites have some difference between the river systems. Especially, the specific design flowrate and specific output of SHP sites located on North Han river and Nakdong river systems have large difference compared with other river systems.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.235-240
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• 2011

Small hydropower resources for five major river systems have been studied. The model, which can predict flow duration characteristic of stream, was developed to analyze the variation of inflow caused from rainfall condition. And another model to predict hydrologic performance for small hydropower(SHP) plants is established. Monthly inflow data measured at Andong dam were analyzed. The predicted results from the developed models in this study showed that the data were in good agreement with measured results of long term inflow at Andong darn. It was found that the models developed in this study can be used to predict the available potential and technical potential of SHP sites effectively. Based on the models developed in this study, the hydrologic performance for small hydropower sites located in river systems have been analyzed. The results show that the hydrologic performance characteristics of SHP sites have some difference between the river systems. Especially, the specific design flowrate and specific output of SHP sites located on North Han river and Nakdong river systems have large difference compared with other river systems.

• 한국추진공학회지
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• 제23권4호
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• pp.98-103
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• 2019

함정 운용 장비의 건전성 예측은 유지보수의 효율성 및 긴박한 상황에서의 운용성능 유지를 위한 필수 요소이다. 최근 함정의 양적인 증가와 작전반경 확대에 따라 운용성능 유지를 위해 통합조건평가시스템(ICAS)을 도입하여 운용중이며, 관련기술 국산화를 위해 다각도로 연구가 진행되고 있다. 본 논문에서는 함정 운용 장비인 디젤발전기의 건전성 예측방법 중 데이터기반 모델 적용에 대한 결과를 제시 하였다.

• 한국환경과학회지
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• 제6권6호
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• pp.645-658
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• 1997

A study on ventilation design using the spreadsheet model is carried out to propose means of available design. A sample of complex ventilation system In the non-standard condition Is used to illustrate thins spreadsheet model. In developing the spreadsheet model, this study has attempted to it general by using computional equations and design parameters that can be readily applied to any spreadsheet software. Also, most design data is contained in the spreadsheet template. This template provides the same design information as the ACGIH worksheet, and operates Quickly and emclenuy, and is fiexible enough to use under different conditions. This spreadsheet model allows the ventilation engineer to design quickly and accurately the ventilation system, without spending too much effort In the design process. By storing on computer and diskette, the design data computed finally can be used as a permanent record of specific ventilation system, and because of finally to be able to design over and over again while making only slight changes to the Input data, the spreadsheet model is used availably to accomplish the design optimazation by redesign and troubleshooting by review from field measurements. Also, the spreadsheet model is available for designing ventilation system under different condition or evaluating existing system or design drawing, because changes In the layout or formulae can be readily made to fit the needs of the designer.