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티타늄 평활관 및 전열촉진관에서 R-l34a의 관외측 풀비등 열전달 특성에 대한 연구
허재혁,윤린,정진택,문영준,김용찬,Heo Jae-Hyeok,Yun Rin,Chung Jin-Taek,Moon Young-lune,Kim Yongchan 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.7
Pool boiling heat transfer characteristics of R-134a were investigated in titanium plain and low finned tubes. The diameter of test tube was 15.88 mm and the fin density was 33 fpi. Tests were conducted at saturation temperatures of $20^{\circ}C$ and $30^{\circ}C$. Heat fluxes varied from 5000 W/$m^2$ to 50,000 W/$m^2$ based on surface area of the plain tube. The pool boiling heat transfer coefficients of the titanium horizontal plain tube are lower than those of the copper plain tube by $8.2\%$. The boiling heat transfer coefficients of the low finned tube are averagely higher than those of the plain tubes by $34\%$. The average deviation of the Slipcevic correlation from the present data for the low finned tube is $20\%$.
허재혁,원혜연,임동규,김정희,김희태,안진영,Heo, Jae-Hyeok,Won, Hye-Yeon,Im, Dong-Gyu,Kim, Jung-Hee,Kim, Hee-Tae,Ahn, Jin-Young The Korean Society of Clinical Neurophysiology 2015 Annals of Clinical Neurophysiology Vol.17 No.2
Background: The effects of omega-3 polyunsaturated fatty acids (PUFAs) on cerebral vessels have not been clarified until now. Thus we investigated the efficacy of omega-3 PUFAs supplementation on cerebral blood flow velocity and vascular resistance via transcranial doppler (TCD). Methods: Consecutive twenty patients (13 male and 7 female) with at least 1 cerebrovascular risk factor or a known cerebrovascular disease were enrolled. Patients were treated with omega-3 PUFAs (1 g, two times per day) for 12 weeks. Cerebral blood flow velocity, resistance index, and pulsatile index were checked before and after 12 weeks of treatment using TCD. Results: The change of resistance index in right MCA (from $0.58{\pm}0.07$ to $0.55{\pm}0.07$, p = 0.042) and left PCA (from $0.56{\pm}0.07$ to $0.53{\pm}0.06$, p = 0.037) showed significant improvement after 12 weeks of omega-3 PUFAs treatment. The changes in other vessels, however, failed to show any significant changes compared to the baseline. Conclusions: Omega-3 PUFAs treatment showed feasible efficacies for cerebral vascular resistances in this open label trial. To confirm these results, larger samples of patients and longer period of follow-up is warranted.
허재혁 ( Jae Hyuk Heo ),강주연 ( Ju Yeon Kang ),이명섭 ( Myong Seob Lee ),조병학 ( Byeong Hak Cho ),황선영 ( Seon Yeong Hwang ),송정훈 ( Jeong Hoon Song ),양주일 ( Ju-il Yang ),최정식 ( Jung Sik Choi ) 대한소화기학회 2016 대한소화기학회지 Vol.68 No.5
Most cystic lesions of the liver are found incidentally in imaging studies because they are not symptomatic, and generally do not require treatment. Rarely, however, symptomatic hepatic cysts may develop complications and require treatment. Here, we describe a case of a 77-year-old woman who developed biliary obstruction with abdominal pain due to compression of the bile duct by a simple hepatic cyst. We confirmed the diagnosis based on symptoms and imaging studies. The patient`s symptoms improved after simple cyst ablation by sclerotherapy. (Korean J Gastroenterol 2016;68:270-273)
발전소 온배수 열회수를 위한 열교환기의 파울링 특성 및 예측
허재혁(Jaehyeok Heo),이동원(Dong Won Lee),김민휘(Min Hwi Kim),윤린(Rin Yun) 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
Available heating energy from Domestic power plant effluent is about 465,182 Tcal, but only a few is used for fishing culture and agriculture and mostly release to the sea. Recently, the power plant heat effluent was included in new and renewable energy in Korea, and the rapid growth of the related research and market are expected. For efficient usage of heat effluent, sea water fouling is a important factor to overcome. In this research, general fouling characteristics in a heat exchanger were investigated and the performance degradation by sea water fouling was estimated.