• 한국환경보건학회지
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• 제32권2호
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• pp.179-185
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• 2006

Effect of organic loading rate on UASB performance was evaluated under the renditions of some surface area/reactor volume ratio and different reactor diameter. At the low leading rate of 0.4 kg $COD/m^3{\cdot}d$, reactor performance was not affected by reactor diameter. At the organic loading rate of 6 kg $COD/m^3{\cdot}d$, however, volatile acid accumulation and low COD removal efficiency is observed in reactor having 6.4 cm diameter, while volatile acid is not accumulated at all and high COD removal efficiency is observed in reactor having 3 cm diameter. Such a difference of reactor performance depending on reactor diameter can be explained that sludge bed can be fluidized by evolved gas bubble in narrow reactor, while sludge bed ran not be fluidized by evolved gas bubble only in wide reactor. At a high organic loading rate of 20 kg $COD/m^3{\cdot}d$, it can be judged that there is no relation between reactor configuration and reactor performance because all reactors showed very low COD removal efficiencies regardless of reactor diameter. Narrow and tall type reactor is favorable condition for making sludge bed fluidization at a constant surface area/reactor volume ratio. Thus, it can be judged that reactor configuration and sludge bed fluidization have great influence to reactor performance.

• Architectural research
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• 제26권1호
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• pp.13-20
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• 2024

This study is a research investigation into the properties of bubbles that affect the characteristics of foamed concrete during its production. The study examined the properties of bubbles based on the manufacturing conditions. To investigate these properties, the selected experimental factors included bead size, the length/diameter ratio of the bubble-generating tube, and compressed air. The experimental design used a design of experiments, and the test results were analyzed using analysis of variance. The foaming agent used to generate bubbles was AES (Alcohol Ethoxy Sulfate), and the method employed for bubble manufacture was the pre-foaming method. In the test results, a significant factor affecting the foaming rate of bubbles was the bead size; the highest foaming rate was observed when using 2mm beads. Bead size also primarily influenced the volume change of the aqueous solution, while other factors did not affect the foaming rate and volume change. None of the factors affected the change in bubble size, but compressed air was considered the main factor affecting bubble size and its change. The foaming rate and volume change of the aqueous solution showed a high correlation with each other. Spherical bubbles in the early stage eventually transformed into angular bubbles. Moreover, over time, it was observed that the bubble size increased.

• 수산해양기술연구
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• 제51권3호
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• pp.454-460
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• 2015

The present study is undertaken to evaluate the effect of volume fraction on the results of Charpy impact test for the rubber matrix filled with nano sized silica particles composites. The Charpy impact tests are conducted in the temperature range $0^{\circ}C$ and $-10^{\circ}C$. The range of volume fraction of silica particles tested are between 11% to 25%. The critical energy release rate $G_{IC}$ of the rubber matrix composites filled with nano sized silica particles is affected by silica volume fraction and it is shown that the value of $G_{IC}$ decreases as volume fraction increases. In regions close to the initial crack tip, fracture processes such as matrix deformation, silica particle debonding and delamination, and/or pull out between particles and matrix which is ascertained by SEM photographs of Charpy impact fracture surfaces.

• 한국측량학회지
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• 제28권5호
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• pp.547-554
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• 2010

본 연구는 생활폐기물매립장의 용적량을 산출함으로써 매립장을 향후 계속하여 언제까지 사용할 수 있는가를 분석한 것이다. 계획용적량을 산출하기 위해서 매립장의 설계 당시의 수지지도 및 계획도 등을 사용하였고, 현재까지의 매립 용적량은 최신의 항공측량장비인 항공 LiDAR 장비를 이용하여 매립량을 측정하였다. 이러한 자료를 바탕으로 현재의 매립 용적량과 지난 수년 간의 반입량, 그리고 그간의 침하량을 산출하였다. 연구 결과, 잉여용적량으로 계산한 대항지역의 매립 가용 년도는 2045년까지로 나타났다.

• Asian Journal of Business Environment
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• 제13권1호
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• pp.31-41
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• 2023

Purpose: This study purposes to analyze the determinants of the volume of Indonesian tuna exports. Research design, data and methodology: The framework was developed from the gravity model for trade, which was expanded with additional variables of competitiveness, exchange rate, and industrial share of the destination country. The data sources used in this study are UN Comtrade and the World Bank. The data used is yearly data from 12 countries in 2001-2019. The scope of the study is limited to exports to the twelve main export destinations. Panel data regression analysis is used to determine the factors that affect the volume of Indonesian tuna exports. Results: The results show that according to the theory, Indonesia's GDP has a positive effect and economic distance has a negative effect on the volume of the exports. Meanwhile, the GDPs of the destination countries are not proven to have a positive effect. However, the higher the industrial share in the country, the higher the export volume tends to be. Conclusions: The conclusion obtained from this study is that Indonesia's GDP, economic distance, real exchange rate, industrial GDP share of the destination country, and the RCA index affect the volume of Indonesian tuna exports.

• Current Research on Agriculture and Life Sciences
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• 제11권
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• pp.55-59
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• 1993

The packed cell volume(PCV) of Korean native goat, volume percentage of red blood cell in whole blood, was reshuffled of 20%, 40% and 60% using autoplasma, and erythrocyte sedimentation rate was measured in Westergren tubes at room temperature ($27{\pm}1^{\circ}C$) and low temperature ($8{\pm}1^{\circ}C$). The sedimentation rates of red blood cell obtained are summarized as follows. The erythrocyte sedimentation rates of Korean native goat are accelerated more at high temperature than low temperature. The erythrocyte sedimentation rates of reshuffled Korean native goat upon time are almost linear for several hours. The erythrocyte sedimentation rates of Korean native goat are settled faster at low PCV than higher PCV, i. e., there is a reverse relationshif between the erythrocyte sedimentation rate and packed cell volume.

• Journal of Welding and Joining
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• 제15권3호
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• pp.47-55
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• 1997

Dynamic characteristics of the short circuit mode are investigated using the Volume of Fluid (VOF) method. When the initial molten drop volume, contact area and wire feed rate are given, rate change of the molten bridge profiles, pressure and velocity distributions are predicted. The electromagnetic force with proper boundary conditions are included in the formulation to consider the effects of welding current. It is found that the molten metal is transferred to the weld pool mainly due to the pressure difference caused by the curvatures in the initial stage, and electromagnetic force becomes dominant factor in the final stage of short circuit transfer. Necking occurs at the contact position between the molten drop and weld pool, and the initial molten drop volume and welding current have significant effects on break-up time.

• 한국연소학회지
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• 제11권2호
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권4호
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• pp.1-8
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• 2017

Efficient groundwater management requires accurate information about the water volume used. The pumped volume of groundwater can be indirectly estimated using empirical formulae based on electric power consumption. The purpose of this study is to test the accuracy of this indirect method. The Haean basin in Gangwon is located in a rural area, where majority of the groundwater extracted is used for irrigation. The pumped volume of groundwater indirectly estimated from electricity usage using these empirical formulae was compared with the actual pumped volume determined by conducting experiments on April 29 and May 19, 2017. The field survey collected data on electricity usage, pumped volume, and groundwater levels. Based on this measured data, correlations were calculated between electricity usage and pumping volume, as well as groundwater level and pumping rate. The results show that electricity usage and pumped volume measured for both wells (YHE1 and YHE2) are highly correlated (r=0.99, p<0.001). However, for YHE1, notably, the correlation between the groundwater level and pumping rate was not significant, and only some correlations were identified for these variables for the YHE2 test well. The average error with respect to the estimation of the actual pumped volume from the existing formula (1) and formulae (2) and (3) are +399% and -88%, respectively. To reduce these errors, these formulae need to consider other factors affecting the pumped volume.

• 멤브레인
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• 제4권1호
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• pp.38-45
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• 1994

계면중합법에 의한 막 제조시 여러 제조변수의 영향을 평가하기 위한 실험을 행하여 다음과 같은 결과를 얻었다. 반응물인 MPD(m-phenylene diamine)농도가 증가할수록 배제율은 증가하나 투과유속은 감소하였다. MPD의 경우에 함침시간이 증가할수록 배제율은 증가하나 투과유속은 감소하였다. TMC(trimesoyl chloride)경우에는 함침시간이 증가할 때 투과유속은 감소한 반면 배제율은 증가한 이후 감소하였다. 열처리 온도가 상승함에 따라 투과유속은 증가하나 배제율은 증가한 이후 감소하였다. 첨가제인 NaOH는 중합시 발생하는 염산의 양이 적어 미량이 중화에 필요하였으며, 그 양이 증가할수록 배제율과 누과유속은 증가한 이후 감소하여\ulcorner. 후처리는 ethanol, isoprophlalcohol, $5~7^{\circ}C$의 물로 치환하여 배제율과 투과유속에서 상승을 가져왔으며, $5~7^{\circ}C$ 물의 경우에는 후처리 시간에 따라 극대값을 가짐을 알 수 있었다.