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핀-관 응축기의 핀과 관의 종류가 성능에 미치는 영향에 관한 수치적 연구
조다영(Da Young Cho),함형창(Hyoung Chang Ham),박창용(Chang Yong Park) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
A numerical study on the effects of tube and fin types on a fin-tube condenser was performed. In the condenser model developed in this study, the air and refrigerant distribution on the condenser was assumed to be uniformed. The model was validated by the comparison with an experimental results. Various correlations were applied for several different types of fins and tubes. Simulation results showed that the condenser with wavy fin and herringbone tube has the largest capacity, even though the capacity difference to other combinations of fins and tubes was small except the usage of plate fin. From the calculated thermal resistance for refrigerant and air side, it was concluded that effect of tube types on the capacity of the condenser, investigated in this study, was small.
불균일 공기분포와 관의 종류에 따른 핀-관 응축기의 성능 특성에 관한 해석적 연구
조다영(Da Young Cho),함형창(Hyung Chang Hahm),박창용(Chang Yong Park) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.12
A numerical study was performed to predict the performance of a fin-and-tube condenser. A condenser model was developed and verified by comparing the simulation results with experimental data for a R410A condenser in a residential air-conditioning system. The prediction error was 0.07% and -5.77% for the condenser capacity and pressure drop, respectively. In simulation results, the capacity and pressure drop of the condenser with even air velocity distribution were 0.67% and 12.93% higher than those with uneven distribution of air velocity. It was predicted by the model that the refrigerant distribution at the condenser inlet to the two first passes was not significantly influenced by the air distribution. The simulation results presented that the 1.49% of capacity and 64.6% of pressure drop were reduced by replacing helical microfin tubes with smooth tubes for the condenser.
Hye-Jin Cheon(천혜진),Sun Young Park(박선영),Hee-Ji Jang(장희지),Da-Young Cho(조다영),Jiwon Jung(정지원),Gimin Park(박기민),Kyeong Mi Jeong(정경미),Jin-Kyung Kim(김진경) 한국생명과학회 2019 생명과학회지 Vol.29 No.4
프로안토시아니딘(proanthocyanidins)은 식물계에 가장 풍부한 폴리페놀성 화합물로 다양한 고등식물의 뿌리, 잎, 열매, 나무껍질 등에 널리 존재할 뿐만 아니라 이러한 원료로 만들어진 차, 와인, 맥주 등과 같은 식품에도 상당량 함유되어 있다. 세포 및 실험동물을 이용한 다수의 연구보고에 의하면 프로안토시아니딘은 항산화활성 및 면역조절활성, DNA 복구 및 항종양 작용과 같은 인체 건강에 유익한 무수한 효과를 가지고 있는 것으로 밝혀졌다. 면역 세포 중 대식세포(macrophage)는 염증반응을 매개하는 중요한 세포로 외부 병원체 제거에 중요한 역할을 수행하고 있다. 그러나 대식세포가 만성 염증을 유발하고 비만, 당뇨병, 대사 증후군 및 암과 같은 다양한 질병에 관여한다는 것 또한 널리 보고되어왔다. 본 연구에서는 마우스의 대식세포주인 RAW264.7세포를 이용하여 프로안토시아니딘의 항염증활성의 일단이 Heme oxygenase-1 (HO-1)의 유도에 의해서 매개됨을 밝혔다. RAW264.7세포에 프로안토시아니딘을 처리한 결과 세포독성을 보이지 않은 농도에서 HO-1의 발현을 증강시켰다. 또한 프로안토시아니딘의 처리는 HO-1의 발현을 조절하는 핵심 전사인자인 Nrf (nuclear factor-erythroid 2-related factor)-2의 핵으로의 이동을 유의적으로 증가시켰다. 프로안토시아닌딘의 처리는 LPS (lipopolysaccharide)에 의해 유도된 NO (nitric oxide)의 생성 및 iNOS (inducible NO synthase)의 발현과 염증성 사이토카인의 생성 및 발현도 유의적으로 억제 하였다. 이러한 결과는 프로안토시아니딘의 항염증제제로서의 개발 가능성을 제시하는 결과이다. Proanthocyanidins are naturally occurring polyphenolic compounds abundant in many vegetables, plant skins (rind/bark), seeds, flowers, fruits, and nuts. Numerous in vitro and in vivo studies have demonstrated myriad effects potentially beneficial to human health, such as antioxidation, immunomodulation, DNA repair, and antitumor activity. Among immune cells, macrophages are crucial players in a variety of inflammatory responses to environmental conditions. However, it has been widely reported that macrophages cause chronic inflammation and are involved in a variety of diseases, such as obesity, diabetes, metabolic syndrome, and cancer. In this study, we report the suppressive effect of proanthocyanidins via the heme oxygenase-1 (HO-1)-related system, on the immune response of the LPS-stimulated mouse macrophage cell line RAW264.7. Increased HO-1 expression at mRNA and protein levels were found in proanthocyanidins-treated RAW264.7 cells. Further, proanthocyanidins enhanced nuclear factor-erythroid 2-related factor 2 translocation into the nucleus. RAW264.7 cells were treated with lipopolysaccharide (LPS) with or without proanthocyanidins, and inflammatory mediator expression levels were assessed. Proanthocyanidins treatment resulted in the attenuation of nitric oxide production and inducible nitric oxide synthase expression in LPS-stimulated RAW264.7 cells. In addition, mRNA and protein expression of proinflammatory cytokines, such as tumor necrosis factor-α and interleukin-6, was inhibited by proanthocyanidins treatment in LPS-stimulated RAW264.7 cells. These findings support proanthocyanidins as a promising anti-inflammatory agent.