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이대희,조헌노,원세열,이영민 인제대학교 1999 仁濟論叢 Vol.14 No.3
본 연구에서는 변압기 냉각용 각-관(Shell and Tube) 열교환기의 성능을 실험적으로 테스트하여 열교환기의 냉각능력을 향상시키는 기술을 개발하고자 하였다. 예열수조 2개를 항온조와 함께 사용함으로써 열교환기 입구에서와 온수의 초기온도를 60℃로 유지하고, cooling tower를 이용하여 입구에서 냉각수 온도를 20℃로 유지하였다. 냉각수 유량변화(5ℓ/min, 10ℓ/min, 15ℓ/min)에 따른 baffle의 형태(Single-segmental baffle, Double-segmental baffle, Disk & Doughnut baffle, Helical baffle)와 baffle의 개수(7개에서 5개) 및 tube의 개수(26개에서 18개)를 변화시켰을 때 열교환기의 냉각능력을 각각 실험하였다. 온수와 냉각수의 입ㆍ출구에서의 온도변화를 측정하기 위하여 Thermocouple을 온수와 냉각수 관의 입ㆍ출구에 하나씩 설치하였다. 실험결과 Disk & Doughnut, Helical baffle, Double-segmental baffle의 열전달률이 Single-segmental baffle보다 5.3%, 5.5%, 11.8% 높고, Double-segmental baffle의 경우 Tube 수의 감소율이 35%일 때 열전달률의 감소율은 14.3%임을 알 수 있었고, baffle의 수가 5개에서 7개로 증가했을 때 열전달률이 12.1% 증가함을 알았다. An experimental study to enhance the cooling capacity of the shell and tube type heat exchanger has been carried out. The initial temperature of hot water in the heat exchanger is maintained at 60℃, using two preheating water baths and one constant temperature water bath, while the coolant temperature is maintained at 20℃ by way of the cooling tower. For the coolant rates of 5 ℓ/min, 10 ℓ/min, 15 ℓ/min, the experiments to determine the heat exchanger cooling capacity have been performed using the various types of baffle(Single- segmental baffle, Double-segmental baffle, Disk & Doughnut baffle, Helical baffle), the number of baffles(from 7 to 5) and number of tubes(from 26 to 18). Thermocouples are installed in the inlet and outlet of hot-water and coolant tube to measure the temperature difference. It was found that the heat transfer rates for Disk & Doughnut baffle, Helical baffle, Double-segmental baffle are 5.3%, 5.5%, 11.8% higher than the Single-segmental baffle, respectively. When the number of tube is reduce by 35%, the 14.3% decrease in the heat transfer rate occurs, while when the number of baffle increases from 5 to 7, the 12% increase in the heat transfer rate occurs.
이대희,원세열,이영민,조헌노 인제대학교 1999 仁濟論叢 Vol.14 No.3
본 연구는 축대칭 난류원형제트가 평판에 충돌하는 경우에 노즐직경이 국소 Nusselt 수 분포에 미치는 영향을 연구하였다. 노즐출구에서의 유동은 완전 발달된 속도형상을 지니고 있다. 그리고, 금박막이 된 Intrex를 사용하여 평판에는 등열유속 경계조건을 형성시켰다 또한, 액정은 평판의 벽면온도를 측정하기 위하여 사용하였다. 실험시 Reynolds 수는 Re=23,000으로 고정하였으며, 노즐과 평판사이의 거리는 L/d=2~14 까지, 노즐 직경은 d=1.36, 2.16, 3.40으로 변화시켰다. 실험결과 정체점과 정체점 영역에서의 Nusselt 수는 노즐 직경이 증가함에 따라 증가함을 알았다. The effect of nozzle diameter on the local Nusselt number distributions has been investigated for an axisymmetric turbulent jet impinging on the flat Plate surface. The flow at the nozzle exit has a fully developed velocity profile. A uniform heat flux boundary condition at the plate surface was created using gold film Intrex. Liquid Crystal was used to measure the plate surface temperature. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle to surface distance (L/d) from 2 to 14., and the nozzle diameter (d) from 1.36 to 3.40 cm. The results show that the Nusselt number at and near the stagnation point increase with an increasing value of the nozzle diameter.
Se-Won Kang,Seong-Heon Kim,Jong-Hwan Park,Dong-Cheol Seo,Ju-Sik Cho 한국토양비료학회 2017 한국토양비료학회지 Vol.50 No.5
This study was conducted to select an optimal approach to corn waste biochar (BC) application, and to evaluate the effects of combined application of BC and inorganic fertilizer (IF) on corn growth and soil chemical properties in a pot experiment. Corn growth differed with BC application timing and BC application levels. Based on the characteristics of corn growth in pot-based experiments, the selected optimal application conditions of BC were application of 500 kg 10a<SUP>-1</SUP> at 20 days before sowing. Also, the chemical properties of the tested soil with BC after corn harvesting were significantly improved than those in the other treatments. In particular, soil pH and CEC regardless of application conditions were markedly increased by 0.04~0.19 units and 0.08~2.58 comlc kg<SUP>-1</SUP> in BC treatments than without BC treatments. Additionally, combined application of BC and IF had greater effects on corn growth than single application of BC. Therefore, the results suggest using properly BC application conditions and a combination of BC and IF for effective corn cultivation in an upland field.
Susceptibility for breast cancer in young patients with short rare minisatellite alleles of BORIS
( Se Lyun Yoon ),( Dae Cheol Kim ),( Se Heon Cho ),( Sang Yeop Lee ),( In Sun Chu ),( Jeong Hoon Heo ),( Sun Hee Leem ) 생화학분자생물학회 (구 한국생화학분자생물학회) 2010 BMB Reports Vol.43 No.10
In this study, we characterized two blocks of minisatellites in the 5` upstream region of the BORIS gene (BORIS-MS1, -MS2). BORIS-MS2 was found to be polymorphic; therefore, this locus could be useful as a marker for DNA fingerprinting. We assessed the association between BORIS-MS2 and breast cancer by a case-control study with 428 controls and 793 breast cancers cases. Rare alleles in the younger group (age, <40) were associated with a statistically significant increased risk of breast cancer (odds ratio, 4.84; 95% confidence interval, 1.06-22.22; and P = 0.026). A statistically significant association between the short rare alleles and cancer was identified in the younger group (8.02; 1.01-63.83; P = 0.021). Kaplan-Meier estimates showed that poor prognosis was associated with patients who contained the rare alleles. Our data suggest that the short rare alleles of BORIS-MS2 could be used to identify the risk for breast cancer in young patients. [BMB reports 2010; 43(10): 698-703]