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생물개스 발생시스템을 위한 지하매설콘크리트 다이제스터의 열전달에 관한 연구
김윤기,고재균 한국농공학회 1980 한국농공학회논문집 Vol.22 No.1
The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.
김윤기,강치원,정회경 한국정보통신학회 2002 한국정보통신학회논문지 Vol.6 No.6
정보통신기술이 발달함에 따라 무선 전자상거래가 활성화되고 있으나 이에 대한 정보가 논문, 보고서 등의 자료로 한정되고 있다. 그러나 최근 들어 전자상거래에 있어서 지적재산권의 중요성이 강조되는 시점에서 이에 대한 연구의 필요성이 크게 대두되고 있다. 이에 본 논문에서는 무선 전자상거래와 관련된 기술 동향 및 이에 관련된 지적재산권에 대해 분석하여 국내의 무선 전자상거래에 관련된 지적재산권 확보 방안 및 지적재산권에 대한 대응 방안을 도출하여 차세대 표준에서 지적재산권 확보를 위한 방향을 제시한다. According to progressing the If(Information Technology), Mobile Commerce have been activated. Hut all kind of theses information is limited in thesis and report. Recently importance of Intellectual Property Right is emphasized and it's very demanded to study for it. Therefore, this thesis will investigate a tendency about Mobile Commerce and Intellectual property Right which is related it. Then it will be presented the way for ensuring the Intellectual Property Right in next generation through seeking a way for guaranteeing Intellectual Property Right of Domestic.