• Membrane Journal
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• v.3 no.1
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• pp.35-39
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• 1993

Reverse osmosis(RO) and pervaporation(PV) membrane separation proceaes were compared with each other experimentally for the system of water-ethanol mixtures by using nylon 4 blended membranes. The separation effciencies of PV were better than those of RO as expected in previous paper covering the theoretical comparisons of both processes, however tbe permeabilities data showed erraerie results due to the membrane imperfections.

• Journal of Life Science
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• v.8 no.5
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• pp.492-496
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• 1998

Intact measurement of leaf water content was attempted using the transmission of beta radiation. Prior to the experiments, two tested plants, rice and soybean, were grown in 1/5000a wagner pot. The moisure ratio of plant leaves were measured with the beta radiation transmission method using a G-M detector and $^{99}$ Tc as the beta ray sou-rce. Beta radiation transmission showed a tendancy to increase with the passage of time after leaf cutting. However, it showed a tendancy to decrease with water supply for the lack of water. A positive correlation was found between the leaf water content and beta radiation transmission. The mutiple regression analysis about leaf water content was obtained that the coefficient of partial regression for beta radiation transmission was much higher(rice; -0.863, soybean; -0.904) than that for specific leaf area(rice; 0.007, soybean: 0.004).

• Membrane Journal
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• v.16 no.3
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• pp.235-239
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• 2006

This study illustrated the results of pervaporation separation using crosslinked poly(vinyl alcohol) (PVA) with poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) for water-ethanol system at 25, 35, and $45^{\circ}C$. The contents of the crosslinking agents were 7, 9, and ll wt% against PVA and the feed compositions of 50, 20, 10 and 4.4% in water were investigated. Typical trends of permeability and separation factor in pervaporation were observed for both the crosslinking agents and operating temperatures. For water : ethanol = 10 : 90, and at $45^{\circ}C$, PSSA-MA 11 wt% membrane showed the permeability $58.92g/m^2{\cdot}hr$ and the separation factor 12003 respectively.

• Progress in Medical Physics
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• v.26 no.4
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• pp.241-249
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• 2015

As radiation therapy is one of three major cancer treatment methods, many cancer patients get radiation therapy. To exposure as much radiation to cancer while normal tissues near tumor get little radiation, medical physicists make a radiotherapy plan treatment and perform quality assurance before patient treatment. Despite these efforts, unintended medical accidents can occur by some errors. In order to solve the problem, patient internal dose reconstruction methods by measuring transit dose are suggested. As feasibility study for development of patient dose verification system, inverse square law, percentage depth dose and scatter factor are used to calculate dose in the water-equivalent homogeneous phantom. As a calibration results of ionization chamber and glass dosimeter to transit radiation, signals of glass dosimeter are 0.824 times at 6 MV and 0.736 times at 10 MV compared to dose measured by ionization chamber. Average scatter factor is 1.4 and Mayneord F factor was used to apply percentage depth dose data. When we verified the algorithm using the water-equivalent homogeneous phantom, maximum error was 1.65%.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.701-706
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• 2007

This study evaluated the durability of high-performance shotcrete mixed in the proper proportions using alkali-free and cement mineral accelerators as a permanent support that maintains its strength for the long term. Durability tests were performed the chloride permeability, repeated freezing and thawing, accelerated carbonation, and the effects of salt environments. Test results showed that all the shotcrete mixes included silica fume had low permeability. In addition, after 300 freeze/thaw cycles, the shotcrete mix had excellent freeze/thaw resistance more than the 85% relative dynamic modulus of elasticity. The accelerated carbonation test results were no effect of accelerator type but, the depth of carbonation was greater in the shotcrete mix containing silica fume. No damage was seen in a salt environments. Therefore, the high performance shotcrete mix proportions used in this study showed excellent durability.

• Membrane Journal
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• v.6 no.1
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• pp.53-57
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• 1996

Polysulfone ultrafiltration membrane was coated with polyisobutylene(PIB) as a top layer to separate chlorinated hydrocarbons. The solubility parameter differences between PIB, water and perchloroethylene(PCE) or trichloroethylene(TCE) show that the solubility parameter difference between PIB and TCE or PCE is similar while that between PIB and water is far less, indicating that PIB is selective to chlorinated hydrocarbons. The pervaporation separation of TCE and PCE shows that TCE is concentrated more than four times, by PIB composite membrane, while PCE is concentrated more than thirteen times. This result shows that PIB composite membrane in this study seems to be an appropriate selective layer for the separation of TCE and PCE from aqueous organic solutions.

• Membrane Journal
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• v.14 no.3
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• pp.258-262
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• 2004

Trifluoroethyl methacrylate (TFEMA) is used in the preparation of water-repellant paints and optical fiber clading materials, and is manufactured by esterification reaction of trifluoroethanol (TFEA) and methacrylic acid (MA). To estimate the applicability of a pervaporation membrane for the esterification TFEMA esterification, the basic pervaporation properties for TFEA/water mixture were determined using a commercial poly(vinyl alcohol) membrane (GFT Membrane $Pervap^{\circledR}1005$). The effect of TFEA concentration in feed solution and operating temperature on the pervaporation properties was determined. The total permeation flux decreased with increasing TFEA concentration from 90 to 99 wt%, but the separation factor of TFEA/water showed maximum values at 95 wt% TFEA concentration. With increasing feed temperatures from 50 to 8$0^{\circ}C$, the permeation flux and separation factor increased. Higher separation factors and permeation fluxes were observed at 8$0^{\circ}C$ of feed temperature. This pervaporation performance confirmed that the commercial pervaporation membrane could be successfully applied to esterification of TFEMA.

• The Journal of the Acoustical Society of Korea
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• v.12 no.2E
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• pp.88-95
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• 1993

공조덕트계에 소음 챔버를 설치하여 발생되는 음향투과손실을 유한요소법에 의하여 산출하는 방법을 검토하였다. 여기서는 음장내의 네트음향인텐시티를 입사파와 반사파의 인텐시티로 분리하므로서 투과손실의 산출을 가능하게 하였다. 산출방법의 타당성을 검증하기 위하여 형상과 내부흡음조건이 다른 소음챔버를 대상으로 수치해석과 모형실험을 실시한 결과, 양자는 잘 일치하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.36-37
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• 1994

시판되는 방향족 폴리아미드계 역삼투막은 우수한 투과특성과 염배제율을 보이고 있다. 하지만 이들 막들은 내염소서의 결핍으로 염소소독시 분해되는 성질이 있어 역삼투특성의 급격한 저하가 일어난다. 이로인해 원수 처리시 전처리 과정으로써 염소살균처리를 하고, RO모듈 입구의 직전에 환원제를 주입하여 잔류염소를 제거하게되므로 공정상의 유지관리가 용이하지 않게된다. 역삼투특성이 우수한 폴리아미드막의 내염소성을 향상시키기 위해 트리메조일클리드를 이요한 가교, 강직한 작용기의 도입 및 친수성기와 소수성기의 고밀도 집적등의 방법으로 개질 폴리아미드막을 제조하는 연구결과들이 보고되었다.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05b
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• pp.110-114
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• 2004

분리막을 이용한 분리기술은 증류, 액체-액체 추출, 탄소 흡착과 같은 일반적인 수분 제거 방법[1,2]에 비해 에너지 소모가 적고 공정이 간단하다는 장점이 있어 알코올/물 혼합계에 대하여 높은 투과 선택성을 갖는 여러 가지 막 소재와 공정개발이 이루어지고 있다.(중략)