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연료 조성과 분사 조건에 따른 LPG 액상 분무의 특성에 관한 연구
이정원(Joungwon Lee),김용래(Yongrae Kim),김만식(Manshik Kim),황승환(Sheunghwan Hwang),민경덕(Kyoungdoug Min) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
Recently, the new Liquid Phase LPG Injection(LPLI) system extends the limits of the primitive LPG engine's<br/> power and improves the control of it. In this study, the amount of LPG spray that was injected at an injection signal<br/> for various conditions was investigated by statistical analysis. With the image of Mie scattering signal from LPG<br/> spray, the structure and penetration length of the liquid phase was measured. In order to certificate the vaporization in<br/> the nozzle line, back-light shadow method was used.<br/> As the injection pressure became higher and the duration grew longer, the amount of injection increased. Spray<br/> structures were influenced by LPG fuel compositions but injection pressure was not dominant factor to determine the<br/> characteristics. As the mixture contained butane more, its vapor pressure became lower and it led to later<br/> vaporization in a nozzle line and spray itself.
LPG엔진에서 이온프로브를 이용한 노킹 발생 위치 추정에 관한 연구
이정원(Joungwon Lee),최희명(Hoimyung Choi),황승환(Seunghwan Hwang),민경덕(Kyoungdoug Min) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_3
LPG has been a broad concern of pro-environmental alternative fuel for vehicles. Recently, the new Liquid Phase LPG Injection (LPLI) system extends the limit of power of LPG engine and gives a chance to substitute LPG engine for diesel engine of heavy duty vehicle which is the main resource of air pollution in urban area.<br/> Large bore size of heavy duty LPG engine derives a serious knock problem. To find an optimal MBT conditions, it is necessary to know how the flame develops in the combustion chamber and find where the knock positions are.<br/> In this study, the ion-probe head gasket was used to estimate the knock position. Inverse operation of the ion-probe signal provides the flame developing characteristics. The further the position is from the spark plug, the later the flame arrives and the more times knock occurs. The main factor that effects knock position is inferred a flow situation of mixed gas in the combustion chamber.
[연료 및 윤활유부문] 대형 LPG 엔진의 노킹 특성에 관한 연구
황승환(Seunghwan Hwang),이정원(Joungwon Lee),민경덕(Kyoungdoug Min) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1
LPG has been well known as a clean alternative fuel for vehicles. Recently, several LPG engines for heavy duty vehicles have been developed, which can replace some diesel engines that are one of the main sources for air pollution in the urban area. Because cylinder bore of heavy duty LPG engine is larger then that of gasoline, The study of knock characteristics of LPG engine are needed.<br/> In this study, The knock characteristics were investigated with various engine speed, air excess ratios and LPG fuel compositions. The Knock occurrence probability decreases when engine speed is higher and propane species of LPG is lower. The Knock occurrence probability is highest at stoichiometry and decreases as the mixture strength became leaner.<br/> <br/>
최희명(Hoimyung Choi),황승환(Seung-hwan Hwang),이정원(Joungwon Lee),민경덕(Kyoungdoug Min) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_1
LPG has been well known as a clean alternative fuel for vehicles. Recently, several LPG engines for heavy-duty vehicles have been developed, which can replace some diesel engines that are one of the main sources for air pollution in the urban area. Because cylinder bore size of heavy-duty LPG engine is larger than that of gasoline. the study of knock characteristics is essential for developing LPG engines.<br/> In this study, three-dimensional transient simulation was performed and a knock model was implemented to predict knock occurrence and autoignition site in a heavy-duty LPG engine. A FAE premixed combustion model and a flame wall-quenching model were applied to simulate flame propagation. A reduced kinetic model was adjusted to LPG fuel and used to simulate autoignition in the unburned gas region<br/> Engine experiments using a single-cylinder research engine are performed to calibrate the reduced kinetic model and to verify the results of this modeling. A pressure transducer and head-gasket type ion-probe circuit board are installed in to detect knock occurrences, flame arrival angles, and autoignition sites.<br/> The simulation result shows good agreements with the cylinder pressures, flame arrival angles, knock occurrences, and autoignition sites of the engine experiments. It also provides much information about in-cylinder phenomena and some ways to reduce knocking tendency. This knock simulation can be used as a development tool of engine design.
地域社會 營養敎育 媒體의 評價 : 국민건강독본 "건강을 지킵시다"에 대하여 on the pamphlet "Let's Stay Healthy"
李貞遠,牟壽美 대한보건협회 1978 대한보건연구 Vol.4 No.1
Nutrition education is a communication activity with a group of people and the communication media has made great contirbutions, whether used alone or combined with face-to-face instruction, to the most of nutrition education programs in developing countries. The media include pamphlet, leaflets, slides, short films, posters, calendars, comic books and charts, etc. CARE, the American non-profit, civil assistance organization for the relief and community development in underdeveloped and developing countries, is one of the most active agencies for nutrition education in Korea. CARE has developed many kinds of nutrition education media. Particularly, two kinds of pamphlets, "What Shall We Eat?" and "Let's Stay Healthy" were published in 1975 and 1977, respectively as a part of the CARE's integrated program of pre-school feeding, nutrition education, and family planning. These pamphlets have been widely distributed to the housewives in rural and suburban area, but without any pre-test. For their better effects, they should have been pre-tested whether their contents had corresponded with the interests and the educational and economic backgrounds of readers, and thus whether the contents had been understandable and applicable to the readers' family food life. Thus this study was undertaken to evaluate the pamphlet, "Let's Stay Healthy" and to get some information's for the next revision of the pamphlet. The pamphlet explains mainly the importance of protein for health and the malnutrition and the diseases with inserted pictures. The. pamphlet was distributed to 48 hourewives randomly selected from the rural area of Sihe-ung-kun and 68 housewives from the suburbs of Suwon city. After they had read through the pamphlets during one week, they answered the questionaire containing 39 questions. The results were as follows: (1) The degrees of interests: Of 116 respondents' 80.5% were interested in reading the pamphlet and the inserted pictures were answered (82.6%) to be also interesting and corresponding with the contents. The percentages were similar through all age, educational, and economic groups. But many readers (29.8%), especially older or low-education group, responded that they could hardly presume the contents by the picture alone. (2) Hardness and easiness: About half (51.8%) of the respondents cuold not understand the meanings of some or many of the words used in the pamphlet and they, particularly low-education group, wanted the pamphlet to had been written in easier words or mostly by pictures. (3) Comprehensiveness: Sixteen questions were asked in practical and applied ways rather than on the nutrition knowledge itself of the pamphlet. Without any significant differences among all age, educational, and economic groups, the respondents showed high degrees of comprehensiveness (the mean score; 81/100). But they seemed not to understand correctly the basic nutrition concepts which did not be explained in the pamphlet and need to be explained more precisely in the coming revision. (4) Effectiveness: Through the pamphlet, 49.1% of the respondents have learned the nutrition knowledge most of which they had not known before and 20.2% have newly learned about the half of the information of the pamphlet. Many (62.3%) of the respondents have become more interested in the family nutrition. With the wide spread of mass communicalion media, mass media has become one of the most effective methods of nutrition education in developing countries. More than half of the respondents had continuously contacted with the nutrition (or family living) programs of mass media such as radio, TV, newspapers, and women's magazine. Among them, over 90% had put into practice, or at least had tried to practice the informations. The result suggested the possible effectiveness of nutrition education through mass media, especially radio which 75.9% owned, if used in Korea.