자연오염세정식 순화유동충 열교환기 내 유동과 열전달

안수환,손강필 경상대학교 농업생명과학연구원 2001 농업생명과학연구 Vol.35 No.-

원통다관형 열환기 내 고체입자들을 자연 순환시켜 오염물질을 세정함으로서 항상 오염이 되지 않는 순환유동층 열교환기를 개발하는데 필요한 기초자료를 제공하고자, 다양한 고체입자들에 따른 열전달과 유동특성의 변화를 조사하고, 또한 장시간에 걸친 오염 실험을 행하여 아래와 같은 결론을 얻었다. 유체 속도가 증가할수록 충돌횟수가 감소하였고 구리의 경우 1.3 m/s이상의 유속에서는 충돌이 이루어지지 않고 상승하였다. 비중이 클수록 대체로 항력계수가 증가하였고 내부 유동일 경우가 외부유동일 경우보다 항력계수가 컸다. Al 입자의 경우 순환 유동층 열교환기의 튜브내 유속을 0.4m/s~0.7m/s 범위로 하면 오염을 제거할 수 있을 뿐만 아니라 열전달계수도 고체입자를 순환하지 않는 열교환기보다 2배 이상의 열전달계수 상승효과를 얻었다. The commercial viability of heat exchanger is mainly dependent on their long-term fouling characteristics because the fouling increases the pressure loss and degrades the thermal performance of a heat exchanger. An experimental study was performed to investigate the characteristics of fluid flow and heat transfer in a fluidized bed heat exchanger with circulating various solid particles. The present work showed that the drag coefficients of particles in the internal flow were higher than in the external flow, in addition, the solid particle periodically hitting the tube wall broke the thermal boundary layer, and increased the rate of heat transfer. Particularly when the flow velocity was low, the effect was more pronounced.

파형관이 있는 순환유동층 열교환기의 유동특성

안수환 경상대학교 농업생명과학연구원 2002 농업생명과학연구 Vol.36 No.4

파형관이 설치된 순환유동층 원통다관형 열교환기의 유동특성에 관한 실험적 연구를 행하였다. 동일한 체적을 가진 7종류의 고체입자들을 열교환기 튜브 속에 순환시켰다. 순환유량, 입자형상, 재료, 그리고 파형관의 형상이 상대속도와 항력계수에 미치는 영향을 조사하였다. 본 연구의 결과 파형관에서의 항력계수는 일반적으로 매끈한 관보다 낮았으나, 물과 고체입자간의 상대속도는 유리입자를 제외하고는 파형관의 경우가 매끈한 경우다 약간 높았다. An experimental study was carried on the characteristics of fluid flow in a fluidized bed shell-and-tube type heat exchanger with corrugated tubes. Seven different solid particles having same volume were circulated in the tubes The effects of various parameters such as water flow rates, particle geometries and materials, and geometries of corrugated tubes on relative velocities and drag coefficients were investigated. The present work showed that the drag force coefficients of particles in the corrugated tubes were usually lower than in the smooth tubes, meanwhile the relative velocities between particles and water in the corrugated tubes were little higher than in the smooth tubes except the glass.

모 컴퓨터 회사 근로자 건강증진 사업 전개를 위한 수요조사

임현우,안병용,최환석,박정일,김경수,이강숙,김정아,구정완 가톨릭대학산업의학쎈타 산업의학연구소 1997 韓國의 産業醫學 Vol.36 No.4

Before conducting the health promotion program, we surveyed the health risk appraisal(HRA) of 210 workers (186 men and 24 women) in a computer company, for the need assessment, selection of target population, priority setting, and as a standard for comparision after performing the program. The smokers were 115(88.6%), and drinkers (over 1 bottle of Soju per week) were 91(44.8%) in men. Entire women and 148(78.0%) men never or irregularly exercise. Type A personality were 73(39.2%) in men, 8(33.3%) in women, and 26(14.0%) of men and 6(25.0%) of women were high stress risk group. 53(25.2%) of men and 2(8.3%) of women were obese (BMI ≥25kg/m²), and workers who consumed exess of total calory compared with recommendation were 142(76.3%) in men and 18(75%) of women. By the health risk appraisal, it was suggested that smoking cessation program, drinking counselling, exercise prescription, stress management, and weight control program should be conducted effectively for the high risk group.

Transthyretin의 Glutathione 자동산화 촉진작용

박종근,정신,김재휴,김수한,강삼석,이제혁,안봉환 대한신경외과학회 1994 Journal of Korean neurosurgical society Vol.23 No.8

When reduced glutathione(GSH) was incubated at neutral pH and at 37°, its concentration decreased slowly with formation of oxidized glutathione(GSSG). Autooxidation of GSH was accelerated by Cu^(2+) and Hg^(2+), but not by other common mono-, di-, and tri-valent cations. Transthyretin was found to stimulate autooxidation of GSH in the presence or absence of Cu^(2+) and Hg^(2+). EDTA inhibited perfectly the autooxidation of GSH regardless of the presence of transthyretin. The stimulating activity of transthyretin was maximal at pH 7.0, declining progressively with increase or decrease of pH from 7.0. Sulfhydryl-blocking agents such as p-hydroxymercuribenzoic acid and Nethylmaleimide markedly inhibited the stimulating activity of transthyretin. Transthyretin stimulated autooxidation of other sulfhydryl compounds such as clithiothreitol and cysteine. However, it did not show a significant effect on autooxidation of sulfhydryl group of egg albumin and eye lens proteins. And transthyretin did not cause any oxidative change to thyroxine(T₄), 3, 5, 3Ltri iodo thyronine(T₃) and 3, 3: 5~triiodothpnine(rT₃) bound to it in the presence of GSH and Cu^(2+). The above results suggest that transthyretin may play a role in regulation of oxidized status of sulfhydryl groups in blood plasma and cerebrospinal fluid

말기신질환을 동반한 다발성 골수종 1예에서 시행된 자가말초혈액 조혈모세포이식

유승민,박정우,이규훈,방수미,안정열,박필환,조은경,신동복,이종호,이재훈 대한조혈모세포이식학회 2002 대한조혈모세포이식학회지 Vol.7 No.2

본 환자는 혈액투석이 요구되는 말기신질환을 동반한 다발성골수종으로 진단받고 VAD 유도요법으로 초기 치료 후 부분관해를 보였으며, melphalan 투여 후 자가말초 조혈모세포이식을 시행하여 심각한 부작용 없이 완전관해를 보이고 그 효과가 1년간 유지되어 이를 보고하는 바이다. Multiple myeloma with monoclonal gammopathy of the lambda light chain, which initially manifested as end-stage renal disease, was diagnosed in a 50-year-old man. Induction chemothery with VAD (vincristine, adriamycin, and dexamethasone) failed to induce a complete response. Complete remission was obtained after high-dose therapy using melphalan (100 mg/m²) followed by autologous peripheral stem cell transplantation. Hemodialysis was performed every day or every other day during induction and high- dose therapy. The adverse events during transplantation consisted of mucositis and neutropenic fever. This case demonstrated that a sustained complete response can be achieved in multiple myeloma complicated by end-stage renal failure using hemodialysis and high-dose chemotherapy without serious toxicity.

Friction Factor and Heat Transfer in Equilateral Triangular Ducts with Surface Roughness

Soo Whan Ahn 대한기계학회 2001 KSME International Journal Vol.15 No.5

An Investigation on Friction Factors and Heat Transfer Coefficients in a Rectangular Duct with Surface Roughness

Soo Whan Ahn,Kang Pil Son 대한기계학회 2002 KSME International Journal Vol.16 No.4

Fully Developed Turbulent Flow in Roughened Concentric Annuli : Experiment and Analysis 실험과 해석

Ahn, Soo Whan 경상대학교 농업생명과학연구원 2002 농업생명과학연구 Vol.36 No.1

직경비가 0.26, 0.39 그리고 0.56인 3종류의 직경비를 가진 거친 환형관내 충분히 발달된 난류유동에 관해 실험과 해석적 연구를 행하였다. 실험적 연구로는 이중 피토튜브와 X형 열선풍속계를 사용하여 최대속도와 전단응력이 0인 지점, 시간평균속도형상, 난류강도, 그리고 마찰계수를 측정하였다. 이론적 연구로는 Reichardt의 수정 난류모델을 이용하여 행하였으며 이론의 결과는 실험연구의 결과와 비교하였다. The fully developed turbulent fluid flows in concentric annuli having artificial roughness elements on either smooth or roughened walls for three radius ratios of 0.26, 0.39 and 0.56 were studied experimentally and analytically. The positions of the maximum velocities and zero shear stresses, mean velocity profiles, turbulent intensities, and friction factors were measured with a double pitot tube and a X-hotwire anemometry system. The analyses were made using a modified Reichardt's turbulence model, and the results from the analyses were compared with experimental data.

An Investigation on Friction Factors and Heat Transfer Coefficients in a Rectangular Duct with Surface Roughness

Ahn, Soo-Whan,Son, Kang-Pil The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.4

An investigation on the fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one-side roughened by five different shapes. The effects of rib shape geometries as well as Reynolds numbers are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the characteristics of heat transfer enhancements, the friction factors are also measured. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones.

Friction Factor and Heat Transfer in Equilateral Triangular Ducts with Surface Roughness

Ahn, Soo-Whan The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.5

Experimental investigations were conducted to study forced convection of fully developed turbulent flows in horizontal equilateral triangular ducts with different surface roughness pitch ratios (P/e) of 4, 8, and 16 on one side. The ducts bottom wall was heated uniformly and the other surfaces were thermally insulated. To understand heat transfer enhancement mechanism, heat transfer rates were measured. Smooth triangular ducts were also tested for benchmark purposes. The results were compared with previous results for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.