• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.7-7
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• 2017

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.581-589
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• 2003

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2％ volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.706-709
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• 1997

Extruders are the heart of the polymer processing industry. The single most important mechanical element of a screw extruder is the screw. The proper design of the geometriy of the extruder screw is of crucial importance to the proper functioning of the extruder. If material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, characteristics design on helix angle of the extruder screw. This paper presents strength of the screw flight, optimum helix angle versus dimensionless down channel pressure gradient, optimum helix angle versus the power law index in simultaneous optimization, volumetric efficiency versus helix angle at various number of flights and power consumption versus helix angle in the barrel of screw extruder.

• 한국환경보건학회지
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• 제30권5호
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• pp.358-365
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• 2004

The photocatalytic oxidation of Rhodamine B(RhB) was studied using photocatalytic reactor filled with module of quartz tube. Module of quartz tube consisted of small quartz tube (inner diameter, 1.5 mm; outer diameter, 3 mm) bundle coated with powder $TiO_2$ and uncoated large quartz tube (inner diameter, 20 mm; outer diameter, 22 mm). Two 30 W germicidal lamp was used as the light source and the reactor volume was 0.5 l. The effects of parameters such as the coating materials and numbers, initial concentration, $H_{2}O_2$ dose and metal deposition (Ag, Pt and Fe) and simultaneous application of $H_{2}O_2$ and metal deposition. The results showed that the initial reaction constant of quartz module coated with powder $TiO_2$ was higher 1.4 time than that of the $TiO_2$ sol and optimum coating number is twice. In order to increase reaction rate, simultaneous application of photocatalytic and photo-fenton reaction using Fe coating and dose $H_{2}O_2$ dose increased reaction rate largely.

• 대한환경공학회지
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• 제29권1호
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• pp.62-67
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• 2007

본 연구의 목적은 액상 균일질 촉매를 이용하여 연소가스 중에 포함되어 있는 $SO_2/NO$의 동시제거 기술 개발에 있다. 연구는 bench scale/소규모 pilot scale에서 이루어졌으며 연구 결과는 다음과 같다. 1) $SO_2$는 실험조건에 상관없이 높은 제거효율을 가지는 것으로 확인되었다. 그러나 NO의 경우 충진층 높이가 증가할수록, 농도가 낮을수록, 촉매 분사량이 증가할수록 제거효율이 증가하는 것으로 나타났다. 2) Fe(II)-EDTA를 이용한 $SO_2/NO$ 동시처리 기술 개발을 위한 최적의 설계 인자는 충진 높이 =0.5 m, 액체-기체비 = 20 $L/m^3$, 반응기 단수=3단, 반응기 단면적 = 0.025 $m^2$로 결정하였다. 3) 연구 결과를 기초로 $SO_2/NO$의 동시처리 효율을 실험한 결과 각각 95%, 81% 이상 제거가 가능했다. 4) 높은 HTU는 NO의 제거에 있어 유리하지만 과도한 HTU는 스크러버의 운전효율을 감소시키므로 최적의 HTU를 결정하는 것이 필요하다.

• 융합경영연구
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• 제9권1호
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• pp.25-40
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• 2021

Purpose: The forecasting is the likelihood scientifically proved judgment about the prospects, the possible conditions of this or that phenomenon in the future and (or) about the alternative ways and the means of their realization. To adapt the instruments of budgeting for the analysis cash flow of company. Research design, data and methodology: The creates the budget of cash flow were carried out on the basis of data of the report for the 2017 of corporations POSCO and in the first half of the 2018 Daewoo Shipbuilding & Marine Engineering of South Korea. Results: The simultaneous use of budgeting techniques and the simple financial analysis allows to systematize the transactions, to identify the main problem areas in the movement cash flows. Therefore, working capital analysis is to determine the limits of their fluctuations in view of the changes in the business processes. Conclusions: In the pedagogical context solved the features of budgeting in the part evaluation current assets, its financing, its elements: the cash, the debtor. In the process of budgeting of cash flow, in credit budget, in financial budget we can see the main indicators: the current assets, the functioning capital, the optimum number of debtors, the optimum amount of cash and another.

• 농약과학회지
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• 제13권3호
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• pp.133-147
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• 2009

토양 중 농약잔류량을 신속하고 저렴하게 분석할 수 있는 다성분 동시분석법을 개발하기 위하여 작물체 중 잔류농약분석법 및 개별성분 분석법을 조사하고 확인하여 기기분석 조건을 확립하였고 분배과정의 용매별 효율성을 조사한 결과는 다음과 같았다. 국내사용농약 중 GC로 분석 가능한 성분 180 성분에 대하여 검출기별 감응성 검토결과 ECD의 경우 84 성분 및 NPD의 경우 113 성분이 예상검출한계 $0.01\;mg\;kg^{-1}$ 이하이었으며 ECD와 NPD를 종합하면 148 성분이었다. 검출한계 $0.05\;mg\;kg^{-1}$ 이하인 농약성분은 ECD 137 성분 및 NPD 170 성분이었고, 두 검출기의 결과를 종합하면 179 성분이 예상 검출한계 $0.05\;mg\;kg^{-1}$ 이하이었다. 농약성분 peak의 분리도와 분석소요시간을 고려하여 선정한 기기분석 조건에서의 머무름 시간 분포를 살펴보면 대부분의 성분이 시료주입 후 10 분에서 40 분 사이에 검출되어 적절하게 분포되었으나, 20 분과 30 분사이의 머무름 시간대에는 90 여 성분이 분포하여 많은 성분이 충분히 분리가 되지 않을 것으로 판단되었다. 분배과정의 회수율은 dichlorornethane이 가장 우수하였으며, 그 다음은 ethyl acetate/hexane 혼합용매, ethyl acetate 순으로 각각 시험대상 성분의 90%, 85% 및 81%가 70-120% 범위의 회수율을 나타내었다. 따라서 dichlorornethane을 두 분배용매체계로 대체하는 것이 가능할 것으로 사료된다.

• 한국식품영양학회지
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• 제13권1호
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• pp.45-52
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• 2000

In order to select the optimum ethanol concentration for extraction of volatile components in cinnamon, the dried cinnamon was extracted with water and 30∼90% ethanol. The volatile components of cinnamon extracts were isolated by the simultaneous distillation extraction method using Likens and Nickerson's extraction apparatus, and analyzed by GC-MS. In cinnamon bark powder 45 components were detected and 21 components were identified. The major component of cinnamon bark powder was cinnamic aldehyde. In water extract of cinnamon, volatile components were not extracted sufficiently. The volatile components of cinnamon were increased with the increment of ethanol concentraction upto 70%. The volatile component of 70% ethanol extract showed similar pattern and amount to cinnamon bark powder. But in 90% ethanol extracts, the number and amount of volatile component were reduced. The above data suggested that 70% ethanol was the most effective solvent for volatile components extraction of cinnamon.

• 한국산업보건학회지
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• 제18권3호
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• pp.189-203
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• 2008

Cylindrical bag filter system with pulse jet cleaning has been the most common device to control particle laden exhaust gas from the various industrial processes. But, it has many shortcomings due to particle reattachment and frequent bag rupture. In recent years, rectangular type bag filter system has been developed to overcome the problems associated with the cylindrical system. However, not many studies about the rectangular system were not done, compared to the cylindrical system. In this study, the optimum pulse jet cleaning conditions were thus tested by the series of experiments. The factors tested in this study are pulse distance, pulse pressure, pulse duration, the number of holes for pulsing and bag materials. A single bag ($1,500mmL{\times}50mmW{\times}300mmH$) system and a multi-bags (3 bags in a row) were tested separately. The highest removal efficiency with a single bag system was found at the conditions with pulse distance of 10cm, pulse pressure of $3kg/cm^2$, pulse duration of 0.3s, pulse jet number of 6 and Polyester bag. With the multi-bags system, the best cleaning conditions were found at the bag interval of 20cm with the simultaneous pulsing and the bag interval of 15cm with the serial pulsing.

• 태양에너지
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• 제8권2호
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• pp.3-11
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• 1988

To suppress the natural convection within enclosure spacing it has been shown theoretically and experimentally that the introduction of cell walls will effectively raise the critical Rayleigh number by providing more shear surfaces within the fluid. For a solar collector, a useful solar thermal converter requires effective control of heat losses. It has been reported that the natural convection can be suppressed and the heat performances of the solar collector increased by placing thin, poorly conducting material honeycomb between the absorber plate and the coverglass. The heat performances were measured and compared directly throughout the simultaneous installation of two solar collectors, one with honeycomb structures fabricated from thin poly carbonate sheet and the other without honeycomb structures. Various tilt angles of 30, 45 and 60 deg. from the horizontal and the honeycomb sizes ($W{\times}H$) of $10{\times}10,\;10{\times}20$ and $10{\times}40mm$ were utilized in the present investigation. It is found that the larger the tilt angle are, the greater the heat losses are, and that the smaller the honeycomb size is, the larger suppression effect of heat losses are. Especially, at tilt angles of 30 degree, the heat use ratio of solar collector with the honeycomb sizes of $10{\times}10mm$ improved approximately 29.5% more than that without honeycomb structures.