• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.4
• /
• pp.1548-1554
• /
• 2013

This paper presents the analysis on performance characteristics of R744-R410A cascade refrigeration system to offer the basic design data for the operating parameters of this system. The performance of cascade refrigeration system is analyzed by using EES program. The operating parameters include compressor efficiency, and condensing and evaporating temperature in R410A high- and R744 low-temperature cycle, respectively. The COP of this system increases with the decrease of condensing temperature, and increases with the increasing evaporating temperature. And the COP of this system increases with the compression efficiency. Therefore, it can be seen that the compression efficiency, and evaporating and condensing temperature of R744-R410A cascade refrigeration system have an effect on the COP of this system. Also, it can be known that the cascade evaporation temperature with the highest efficiency in each parameter is present. Thus, it is an important to design R744-R410A cascade refrigeration system by considering these parameters.

• 건강소식
• /
• v.2 no.11 s.14
• /
• pp.10-11
• /
• 1974

• The Korean Publising Journal, Monthly
• /
• s.327
• /
• pp.177-177
• /
• 2003

• 건강소식
• /
• v.23 no.7 s.248
• /
• pp.4-7
• /
• 1999

이원종 충청북도지사는 늘 바쁘다. 21세기를 앞두고 더 많이 발전하고 활력이 넘치고 무궁무진한 새로움으로 거듭나는 충북을 만들기 위해 동분서주하기 때문이다. 그러나 충북도민들은, 이 지사를 일상 생활에서 쉽게 만나고 대화할 수 있다. 아무리 바빠도 도민의 일상을 돌아보기 위한 행보는 절대 뒤로 미루지 않는 그의 고집(?) 덕택이다. 농협 물류센터나 장터, 도민의 일터에서 자주 그의 환한 미소를 접할 수 있는것도, 현실을 체험하지 않으면 바른 길이 나오지 않는다는 그의 신념의 표출이라 해야 할 것이다. 서울특별시장을 비롯한 요직을 거치는 동안 국민과 함께 하는 자세, 밝고 건강한 웃음과 사랑을 단 한번도 버리지 않은 이원종 지사를 만났다.

• Journal of the Korean Institute of Gas
• /
• v.14 no.1
• /
• pp.1-7
• /
• 2010

In this paper, cycle performance analysis of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The main results were summarized as follows : The COP of two-stage cascade refrigeration system increases with the increasing subcooling degree, but decreases with the increasing superheating degree. The COP of two-stage cascade refrigeration system decreases with the increasing condensing temperature, but increases with the increasing evaporating temperature. And the COP of two-stage cascade refrigeration system increases with increasing the compressor efficiency. Therefore, superheating and subcoolng degree, compressor efficiency, and evaporating and condensing temperature of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system have an effect on the COP of this system.

• Applied Biological Chemistry
• /
• v.39 no.6
• /
• pp.419-423
• /
• 1996

We have established the quantitative method for assay antimutagenic activity from natural products using SOS chromotest technique. Establishment of the method in this study makes it possible to numerize antimutagenic activities from samples in term of the sample amount required for 50% inhibition to mutagenic activity induced by the chemical mutagen under the standard assay condition. Antimutagenic activities of rices from different cultivars as well as other cereals were assayed through this method. The results revealed that antimutagenic activities of mutant cultivar, Suwon 393(Hyangdo) and Sanghaehyanghyulla(Jado), were higher than Chuchung which mainly consumed for steamed rice, and also indicated that antimutagenic activities of cereals, such as job'tear, buckwheat, small red bean, black bean were generally higher than that of brown rice.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2004.07a
• /
• pp.1-17
• /
• 2004

• The Journal of Korean Association of Computer Education
• /
• v.10 no.1
• /
• pp.89-96
• /
• 2007

Two-way specification table for educational objectives proposed by B.S.Bloom, which is useful in reviewing and determining the objectives of instructions, is widely used in schools. However, differences in subject matters and school environments require various types of two-way specification table. Extensible markup language (XML) can be effectively applied for two-way specification table for educational objectives because it is well structured and the content of an XML document can be separated from its presentation. In this paper, the document type definition (DTD) for two-way specification table was designed. An example of XML document and XSL style sheet for the table were also presented. Furthermore, applications of the designed DTD were discussed. It is expected that the proposed DTD can be useful to various applications related to education assesment.

• Landscaping Tree
• /
• v.2 no.5
• /
• pp.10-17
• /
• 1991

• Landscaping Tree
• /
• v.4 no.9
• /
• pp.10-11
• /
• 1991