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이경훈,문병석,남길정,강일환 대한상하수도학회 2002 상하수도학회지 Vol.16 No.2
To develop the forecasting model on hydrologic rainfall-runoff process, this fuzzy theory is applied in this study, that is the mathematical theory to process ambiguity and the neural network theory, that is applied human's empirical thinking to mathematical process. As the result of applying neural network theory, the model of linear-linear, linear-nonlinear in the transfer function and the model applying fuzzy theory showed the excellent expectation that a coefficient of determination is over 0.97, percent error of maximum flow is less 10%. This result showed that neural network and fuzzy theory have excellent applicability in the flood forecasting. And this study expect that neural network and fuzzy theory can be used as the approach to settle problems being occurred in the course of rainfall-runoff modeling.
문병석,이경훈,강일환 대한상하수도학회 2000 상하수도학회지 Vol.14 No.3
This study investigates the prediction of daily water supply, which is a necessary for the efficient management of water distribution system. ANFIS, namely artificial intelligence, is a neural network into which fuzzy information is inputted and then processed. In this study, daily water supply was predicted through an application of network-based fuzzy inference system(ANFIS) for daily water supply prediction. This study was investigated methods for predicting water supply based on data about the amount of water which supplied in Kwangju city. For variables choice, four analyses of input data were conducted: correlation analysis, autocorrelation analysis, partial autocorrelation analysis, and cross-correlation analysis. Input variables were (a) the amount of water supply, (b) the mean temperature, and (c) the population of the area supplied with water. Variables were combined in an integrated model. Data of the amount of daily water supply only was modelled and its validity was verified in the case that the meteorological office of weather forecast is not always reliable. Proposed models include accidental cases such as a suspension of water supply. The maximum error rate between the estimation of the model and the actual measurement was 18.46% and the average error was lower than 2.36%. The model is expected to be a real-time estimation of the operational control of water works and water/drain pipes.
김병삼(Byoung-Sam Kim),장일도(Il-Do Chang),이봉구(Bong-Goo Rhee),문상돈(Sang-Don Mun) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.3
Torque fluctuation of an engine and angular velocity variation of a propeller shaft are the main excitation sources in a vehicle driveline. This paper presents the mechanism of these excitation sources. An equivalent model of the engine system and propeller shaft system is constructed to simulate the excitation phenomena. The analytical model contains the geometrical and dynamic mechanism. Combustion pressure of the cylinder is measured from dynamometer. The computer simulation is carried out by commercial program package. Results of the simulations show the characteristics of the torsional excitation source of the driveline.
울산지역에서 주폐경기 ( Perimenopause ) 여성의 골다공증 유병률과 연관인자
김영일(Young Il Kim),박재후(Jae Hoo Park),이종수(Jong Soo Lee),김진우(Jin Woo Kim),양승오(Seoung Oh Yang),전대준(Dae Joon Jeon),김문찬(Mun Chan Kim),정태흠(Tae Heum Jeong),이윤구(Yoon Gu Lee),이병두(Byoung Doo Rhee) 대한내과학회 2002 대한내과학회지 Vol.62 No.1
N/A Background: Osteoporotic fractures pose a major public problem, not only in Western populations but also of increasing significance in Asian populations. However, most previous studies for the prevalence of osteoporosis in Korea were carried out from the data of hospitalized or out-patient based subjects, hospital staff, healthy volunteers and so forth. The purpose of present study was to evaluate the normative data of bone mineral density (BMD) in Korean young and perimenopausal women and to determine the prevalence and risk factors of low bone mass, including osteoporosis and osteopenia in a community- based population. Methods: In 1999, a baseline survey was carried out in the Dong-gu of Ulsan city, a urban area but located in seashore of southeastern Korea. The selected community sample of 3,822 inhabit ants (all were women aged 49-54 years) were chosen. We studied 1,629 women among them and 127 healthy women aged 20-35 years. BMD of lumbar spine and femur was measured using dual-energy X-ray absorptiometry. For analysis of risk fact ors, those were excluded who was the current or recent user of estrogen and who had osteoporosis related disease or unknown menopause due to previous hysterectomy. Thus, 1,020 subjects were analysed for the association of low BMD and risk factors. Significant determinants of BMD were investigated using univariate and multiple regression analysis. Results: When our young normal data were used, 9.8% for the lumbar spine and 1.4% for the femoral neck of our study population (n=1,629) were classified as osteoporosis. Among them, the menopausal status of above 1,020 subjects had independent association with low BMD (T-score<-1.0) of both lumbar spine (odds ratio=4.71 in postmenopause, p <0.001) and femoral neck (odds ratio=2.86 in postmenopause, p <0.001). In premenopausal women (n=507), weight and age of menarche were associated independently with low bone mass, including osteoporosis and osteopenia of both lumbar spine and femoral neck. In postmenopausal women (n=513), weight and duration since menopause were associated independently with low bone mass of both lumbar spine and femoral neck. Also, daily amount of calcium intake had significant association (regression coefficient =0.047; p <0.05) independently with BMD of femoral neck. Conclusion: The result s of this population-based study suggest that it is import ant to prevent bone loss and screen the BMD in women aged 49-54 years with menopause, low body weight, late menarche, prolonged duration since menopause, low calcium intake.(Korean J Med 62:11- 24, 2002)