• 기술사
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• 제2권6_7호
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• pp.12-23
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• 1969

The purpose of this study is to find out the reasonable amount of evapo-transpiration required for the paddy rice plant during the whole growing season. So, on the basis of the 3year experimental data concerning the evapo-transpiration from 1966 to 1968, the author obtained the following results. 1) The leaf area index in the densely planted plot is generally higher than that in the conventionally planted one during the first half of growing season. So, the coefficient of transpiration in the former plot is some what higher than in the latter, and the coefficient of water surface evaporation under the plant cover has the inverse relation between both plots. 2) It is unreasonable that coefficient of evapo-transpiration is applied to the calculation of the evapo-transpiration requirments of each growing stage, because a certain degree of variation in meteorological factors and in the thickness of the plant growth is involved in it. 3) It is most reasonable that the rate of transpiration and of the water surface evaporation is applied to the calculation of the transpirated amount and evaporated one in each growing stage because it shows almost constant value in spite of any meteorological conditions in so far as the variety of rice, planted density and control of applying fertilizer are same and the disease and blight are negligible. 4) The ratio of the amount of transpiration to the weight of the whole air dried yields has the tendency of decreasing as that of the yields increase, having almost constant value despite the amount of pan evaporation; and the value is about 210 when the weight of root parts is included to that of the yields. 5) Although the required amount of transpiration during the whole growing season can be calculated with the above ratio, fig. 7 showing the relation between the amount of transpiration and the weight of the yields is more reasonable and will be convinient to find it. And the requirements of water surface evaporation during the same season can also be directly found with the weight of air dried straw refering to fig.8.

• 한국세라믹학회지
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• 제35권6호
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• pp.543-550
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• 1998

에멀젼 증발법에 의해 구형의 산화텅스텐 분말을 제조하는 연구를 하였다. 분말의 특성은 TGA, X-ray 회절, SEM, image analysis 등을 이용하여 조사하였다. 텅스텐 이온이 함유된 수상과 등유, 계면활성제, 파라핀유로 이루어진 유기상을 고속으로 교반하여 에멀젼을 제조하였다. 에멀젼을 $160^{\circ}C$의 등유욕내에서 증발시틴 후 얻어진 침전물을 $160^{\circ}C$에서 하소하여 텅스텐 산화 분말을 제조하였다. 산화텅스텐 분말의 평균 입경은 $0.5\;\mu\textrm{m}$ 였으며 모양은 구형이었다. Watre-in-oil형 에멀젼으로 제조된 $W_{3}$는 oil-in-water 형의 것보다 응집도가 적었다. 계면활성제의 HLB값이 증가할수록, 에멀젼 중의 텅스텐 이온의 농도가 감소할수록 평균입도가 작아졌으며, $W_{3}$ 입자들의 응집도는 증가하였다. 계면활정제로 사용한 Span 80의 농도는 8 vol%가 적당했고, 에멀젼 제조시 교반속도는 5000rpm이 적당했다.

• 대한기계학회논문집B
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• 제24권7호
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• pp.938-944
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• 2000

Recently, micro fin tube is widely used to heat exchanger for high performance. And, as the alternative refrigerants for R-22, hydrocarbons such as R-290, R-600 and R-600a are very promising because of their low GWP and ODP. Thus, R-290 was used as working fluid in this study. Most design of heat exchanger had been based on heat transfer characteristics of pure refrigerant although refrigerant oil exists in the refrigeration cycles. So, the influence of oil on heat transfer characteristics have to be considered for investigating exact evaporation heat transfer characteristics. But, this is an unresolved problem of refrigeration heat transfer. Therefore the influence of the refrigeration oil to the evaporation heat transfer characteristics of R-290 were conducted in a horizontal micro tin tube. The mineral oil was used as refrigeration oil. The experimental apparatus consisted of a basic refrigeration cycle and a system for oil concentration measurement. Test conditions are as the follows; evaporation temperature $5^{\circ}C$, mass velocity 100 $kg/m^2s$, heat flux 10 $kW/m^2$, oil concentration 0, 1.3, 3.3, 5.7 wt.%, and quality $0.07{\sim}1.0$. When refrigeration oil was entered, oil foaming was observed at the low quality region. And, very small bubbles were observed as quality was increased. Pressure drop and heat transfer coefficient increased as the concentration of refrigeration oil increased to 5 wt.%.. The performance index of heat exchanger was the highest near 3.3 wt.%.

• 설비공학논문집
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• 제20권7호
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• pp.462-469
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• 2008

A regenerative evaporative cooler has been fabricated and tested for the evaluation of cooling performance. The regenerative evaporative cooler is a kind of indirect evaporative cooler comprised of multiple pairs of dry and wet channels. The air flowing through the dry channels is cooled without any change in the humidity and at the outlet of the dry channel a part of air is redirected to the wet channel where the evaporative cooling takes place. The regenerative evaporative cooler fabricated in this study consists of the multiple pairs of finned channels in counterflow arrangement. The fins and heat transfer plates were made of aluminum and brazed for good thermal connection. Thin porous layer coating was applied to the internal surface of the wet channel to improve surface wettability. The regenerative evaporative cooler was placed in a climate chamber and tested at various operation condition. The cooling performance is found greatly influenced by the evaporation water flow rate. To improve the cooling performance, the evaporation water flow rate needs to be minimized as far as the even distribution of the evaporation water is secured. At the inlet condition of $32^{\circ}C$ and 50%RH, the outlet temperature was measured at $22^{\circ}C$ which is well below the inlet wet-bulb temperature of $23.7^{\circ}C$.

• 한국지반공학회논문집
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• 제32권5호
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• pp.37-48
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• 2016

본 연구는 실제 시공 환경에서 투수성 보도블록의 표면 유출 및 배수 특성을 알아보고자 하였으며, 표층 및 노반을 포함한 시편을 대상으로 불포화 상태에서 도심 내 우수 조건을 고려한 배수 실험을 진행하였다. 일정한 시간 간격을 두고 반복적인 배수 실험 및 공극 막힘 실험이 시행되었으며, 정량적 분석을 위하여 3D X-ray CT 이미지 분석 및 증발 실험을 시행하였다. 실험 결과, 시간 간격 동안 발생한 증발로 인해 공극 내 물이 공간적으로 재분포되어 표면 유출을 야기시키는 것으로 나타났다. 특히, 공기에 노출되어 있는 표층보다 시편 하부에 위치한 노반의 공극 변화가 투수성 보도블록의 배수, 증발 등 전체적인 수리학적 거동을 크게 저하시켰다. 또한 공극 내 침전물은 증발로 인한 변화를 증진 시키며, 이 때 저하된 배수 성능은 쉽게 회복되지 않는 것으로 나타났다. 그리고 선행우수조건에 의하여 배수 성능이 저감되면서 최대 표면 유출 높이가 증가하는 것으로 나타났다.

• 한국가스학회지
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• 제12권3호
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• pp.43-49
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• 2008

본 연구에서는 내경 4.3 mm와 6.4 mm의 수평동관내 R-22와 R-407C의 증발 열전달과 압력강하를 실험적으로 조사하였다. 냉매 순환루프의 주요구성품은 수액기, 압축기, 질량유량계, 응축기, 이중관식 증발기 (시험부)로 구성된다. 시험부는 내경 4.3 mm와 6.4mm의 평활 동관으로 이루어져 있다. 냉매질량유속은 $100\;kg/m^2s$에서 $300\;kg/m^2s$까지 변화시켰고, 증발기 냉매포화온도는 $5^{\circ}C$이다. R-22와 R-407C의 증발 열전달계수는 질량유속과 증기건도의 증가와 함께 따라 상승한다. 내경 4.3 mm와 6.4mm관내 R-22의 증발 열전달계수가 R-407C에 비해 각각 $7.3{\sim}47.1%$와 $5.68{\sim}46.6%$ 정도 높다.

• Restorative Dentistry and Endodontics
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• 제40권3호
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• pp.202-208
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• 2015

Objectives: This study determined the effect of the air-stream application time and the bonding technique on the dentin bond strength of adhesives with different solvents. Furthermore, the content and volatilization rate of the solvents contained in the adhesives were also evaluated. Materials and Methods:Three adhesive systems with different solvents (Stae, SDI, acetone; XP Bond, Dentsply De Trey, butanol; Ambar, FGM, ethanol) were evaluated. The concentrations and evaporation rates of each adhesive were measured using an analytical balance. After acid-etching and rinsing, medium occlusal dentin surfaces of human molars were kept moist (conventional) or were treated with 10% sodium hypochlorite for deproteinization. After applying adhesives over the dentin, slight air-stream was applied for 10, 30 or 60 sec. Composite cylinders were built up and submitted to shear testing. The data were submitted to ANOVA and Tukey's test (${\alpha}=0.05$). Results: Stae showed the highest solvent content and Ambar the lowest. Acetone presented the highest evaporation rate, followed by butanol. Shear bond strengths were significantly affected only by the factors of 'adhesive' and 'bonding technique' (p < 0.05), while the factor 'duration of air-stream' was not significant. Deproteinization of dentin increased the bond strength (p < 0.05). Stae showed the lowest bond strength values (p < 0.05), while no significant difference was observed between XP Bond and Ambar. Conclusions: Despite the differences in content and evaporation rate of the solvents, the duration of air-stream application did not affect the bond strength to dentin irrespective of the bonding technique.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권3호
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• pp.20-26
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• 2004

2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD)로 오염된 토양의 현장 광분해 정화 과정에서 가장 중요한 이동 메커니즘인 지표에서의 증발 및 광분해에 의한 유기 용매의 이류 상방향 이동에 대한 수식화와 모델 개발을 수행하였다. 각 유체 분포에 대한 다상 유동 효과, 구동력으로서의 중력, k-S-p 관계의 정확한 묘사를 위한 van Genutchen 방정식을 포함한 유한요소법 기반의 수치 모델을 제안하였다. 실험실 규모의 비포화 토양 컬럼 내 용매 이동에 중요한 영향을 미치는 인자들을 조사하기 위하여 수행한 계산의 결과들을 제시하였다. 중력은 고투수성 토양의 유체 분포와 증발에 상당한 영향을 미쳤다. 토양의 종류 또한 증발 과정 중 유체 포화도 분포에 큰 영향을 미친다. 용매의 이류 이동량은 증발량이 증가할수록 초기 물 포화도가 감소할수록 증가하였다. 본 연구에서 수행한 시뮬레이션은 개발된 모델이 토양 환경 내에서 유기 용매의 이류 이동에 영향을 미치는 다양한 인자들의 영향을 분석하는데 유용함을 보여준다.

• 대한금속재료학회지
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• 제50권1호
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• pp.78-85
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• 2012

Aluminum nitride(AlN) is a compound (III-V group) of hexagonal system with a crystal structure. Its Wurzite phase is a very wide band gap semiconductor material. It has not only a high thermal conductivity, a high electrical resistance, a high electrical insulating constant, a high breakdown voltage and an excellent mechanical strength but also stable thermal and chemical characteristics. This study is on the preferred orientation characteristics of AlN thin films by reactive evaporation using $NH_3$. We have manufactured an AlN thin film and then have checked the crystal structure and the preferred orientation by using an X-ray diffractometer and have also observed the microstructure with TEM and AlN chemical structure with FT-IR. We can manufacture an excellent AlN thin film by reactive evaporation using $NH_3$ under 873 K of substrate temperature. The AlN thin film growth is dependent on Al supplying and $NH_3$ has been found to be effective as a source of $N_2$. However, the nuclear structure of AlN did not occur randomly around the substrate a particle of the a-axis orientation in fast growth speed becomes an earlier crystal structure and is shown to have an a-axis preferred orientation. Therefore, reactive evaporation using $NH_3$ is not affected by provided $H_2$ amount and this can be an easy a-axis orientation method.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.330-330
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• 2016

The quantification of dry season evaporation in regions, where the magnitude of dry season flows is key to the regional water supply, is essential for good water management. Also, tree transpiration has a significant role in the water balance of a catchment whenever it is tree populated, especially in water limited environments. Such is the case in the Middle Mountains of Nepal where dry season flows play a significant role in downstream water provisioning and their proper functioning is key to the welfare of millions of people. This research seeks to study the transpiration of a pine forest stand in the Jikhu Khola Watershed in the Middle Mountains of Nepal. To the author's knowledge, no single study has been made so far to estimate the dry season evaporation from the planted forest stand in the Middle Mountains of Nepal. The study was carried out in planted pine forest embedded within the Jikhu Khola Catchment. Field campaigns of sap flow measurements were carried out from September, 2010 to February, 2011 in the selected plot of 15*15m dimension, to characterize dry season evaporation. This was done by measuring sap fluxes and sapwood areas over the six trees of different Diameter at Breast Height (DBH) classes. The sap flux was assessed using Granier's thermal dissipation probe (TDP) technique while sapwood area was determined using several incremental core(s) taken with a Pressler borer and immediately dyeing with methyl orange for estimating the actual depth of sapwood area. Transpiration of the plot was estimated by considering the contribution of each tree class. For this purpose, sap flux density, sapwood area and the proportion of total canopy area were determined for each tree class of the selected plot. From these data, hourly and diurnal transpiration rates for the plot were calculated for experimental period. Finally, Cienciala model was parameterized using the data recorded by the ADAS and other terrain data collected in the field. The calibrated model allowed the extrapolation of Sap flux density (v) over a six month period, from September 2010 to February 2011. The model given sap flux density was validated with the measured sap flux density from Grainier method.