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임종한,김환철,이지영,손종렬 환경독성보건학회 2011 환경독성보건학회지 Vol.26 No.-
Objects: The prevalence of asthma has increased in recent decades globally. The objective of the present study is to elucidate whether hospitalization for bronchiolitis in infancy and low socioeconomic status interact for bronchial hyperreactivity during teenage years. Method: We studied 522 children age 13-14 years attending schools in rural and urban areas to investigate the risk factors for bronchial hyperreactivity (BHR), defined as a provocation concentration of methacholine that causes a decrease of 20% (PC20) in forced expiratory volume within 1 second. Clinical examination, skin prick test, spirometry, and methacholine challenge were performed on all study subjects,who provided written consent. We used multivariate logistic regression to investigate the risk factors for BHR, and analyze the interaction between hospitalization for bronchiolitis in infancy and low socioeconomic status. Results: Forty-six (10.3%) positive BHR cases were identified. In the multivariate logistic analysis, as independent predictors of BHR,adjusted odds ratio of bronchiolitis diagnosed before 2 years of age in low income families was 13.7 (95% confidence interval, 1.4 to 135.0),compared to reference group, controlling for age, gender, parental allergy history, skin prick test, and environmental tobacco smoke (ETS)exposure. Interaction was observed between bronchiolitis before 2 years old and low socioeconomic status on children’s bronchial hyperreactivity (p-interaction=0.025). Conclusions: This study showed that bronchiolitis diagnosed before 2 years of age and low socioeconomic status interacted on children’s bronchial hyperreactivity. Prevention of acute respiratory infection in early childhood in low socioeconomic status is important to prevent BHR as a precursor of asthma.
임종한,이종원 대한기계학회 1992 대한기계학회논문집 Vol.16 No.5
본 연구에서는 산업용 가스전소자연순환보일러를 모델로 선정하여 이 모델에 영향을 주는 인자에 대하여 동적 해석을 하였다. 수위와 압력을 연결한 자연순환 보일러의 제어를 위한 총괄적인 블록 선도를 제시하였고, 이 선도를 토대로 전산프로 그램을 개발하고 계산치와 실제 측정치를 비교, 검토하여 이론 해석상의 모순이 없음 을 확증하였다. 연구결과를 산업용 자연순환 gas 보일러의 설계에 응용하도록 하여 보일러의 동특성을 제시하고 이것에 의한 전제어시스템의 신속하고 정확한 설계치를 제시하여 응용사용토록 하여 무엇보다도 전보일러시스템의 안전운전과 경제성(제작비 및 가동비)을 제고하는데 있다. 본 논문을 제1부, 제2부로 나누어 발표해야 하므로 제1부는 결론을 포함시키지 못하며 제2부에서 결론을 제시하겠으니 참조하여 주시기 바랍니다. Boilers, which are considered to be one of the basic equipment in industry, consume large potion of nation's petroleum and their demand is growing everyday. In recent, the technology improvement in production of high efficiency boilers and their effective utilization is needed for design of boiler which steam condition is the large capacity of high temperature and high pressure. It is necessary that boiler control system be studied for high efficiency, high reliability and smooth operation. The control of drum pressure and water level particularly becomes an important task for greater accuracy with the avail ability of boiler operation. To achieve this aim, dynamic analysis of a boiler is accomplished by choosing a boiler as a model. Transfer function thus obtained is made a comparison of measurement with reckoning to technical design data. The results of comparison makes it possible to verify thermodynamical analysis on the dynamic behavior of the overall system.
Experimental Study on the Flow-field and the Atomization Characteristics of Gas-liquid Compound Jets
임종한 경원전문대학 2000 論文集 Vol.22 No.-
The study on the flow-field of gas-liquid compound jets has been presented in this paper. Compound jets is liquid and air flow in a central area and circumferential area and circumferential area, respectively. Experiments were performed to investigate spray characteristics, fundamental structure of gas-liquid two phase flow for coaxial injector with W1/W2 less than 0.6. Velocity of gas phase and flux profile of liquid flux in the main region is to be Gauss distribution regardless of distance from coaxial injector and is able to represent Eq.(2) and (3), respectively. Velocity profile of gas phase increases with a certain slope(≒4.60 in axial direction, but the slope is smaller than of a one phase gas jet(≒6)). The slope of liquid flux is much smaller(≒3.1). Dimensionless liquid flux profile decreases with a slope of 1.5. Diffusion of droplets is not affected much by high gas-liquid flow rate, but optimal gas-liquid flow rate exists for maximum diffusion.
임종한,박승철,이종원 慶熙大學校 大學院 1993 高凰論集 Vol.12 No.-
The purpose of this thesis is to analyze the dynamic characteristics of industial natural circulation gas boiler which is economical and reliable with speedy and accurate control ability, and to make the analysis utilized for the design of control in industry. A linear differential equation for the control is derived from its physical variation process with time by Laplace conversion. Then from the equation we get a transfer function for pressure and water level in drum. This means that a transfer function for the control system must be carried out from manipulated variables such as Ma, M_FU, M_W and θ_FW to controlled variables such as pressure and water level in drum. Two kinds of methods are used to induce these processes. According to the research on the influence Ms and M_FU as major variable of control system of industrial natural-circulation gas boiler have on pressure and water level in drum, the following satisfactory result can be obtained; if Ms is cut down 15% by the hour, the difference between the measurement and reckoning of transfer function by Method-Ⅱ is 12.4% in pressure variation and 21.7% in water level variation. This means that only transfer function for the control system by Method-Ⅱ is correct.