• 한국염색가공학회지
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• 제3권2호
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• pp.34-42
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• 1991

The effects of electrolyte on dyeing properties of cotton fiber with Congo Red have been studied at 90, 70 and $40^{\circ}C$. Each dyeing carried into an infinite bath with $1\times10^{-4}$ mol/l of Congo Red and with various concentration of electrolytes. The results obtained from this study were as follow; 1. The equilibrium adsorption of dye $(C_\infty)$ values decreased with increasing dyeing temperature, $C_\infty$ values increased in the order KCl>NaCl>LiCl. 2. The values of apparent diffusion coefficients $(D_a)$ increased with increasing dyeing temperature, but $D_a$ values decreased in the order KCl$D_a$ values decreased with increasing electrolyte concentration. 4. Effect of electrolytes decreased with increasing dyeing temperature. 5. The values of standard affinities of dyeing $(-\triangle\mu^{\circ})$, the standard heats of dyeing $(-\triangleH^{\circ})$, and the standard entropies $(-\triangleS^{\circ})$, increased in the order KCl>NaCl>LiCl. 6. Equilibrium adsorption isotherm curve were Freundlich type, and in the Equation y=a.x$^{n}$ , the values of a and n increased in the order KCl>NaCl>LiCl. 7. The value of $-\triangle\mu^{\circ}$, $-\triangleH^{\circ}$, and $-\triangleS^{\circ}$, decreased with increasing electrolyte concentration.

• 한국환경보건학회지
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• 제42권3호
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• pp.160-168
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• 2016

Objectives: Materials coming into contact with food may result in the migration of chemical substances into the food. To protect consumers from exposure, Regulation (EU) No. 10/2011 specifies the use of standard migration tests. Polyethylene terephthalate (PET), widely used for food packaging materials, has drawn the attention of researchers because unwanted migration of PET into food might occur when consumers reuse packaging material. The aim of this study was to predict and develop a migration model for two components, acetaldehyde and butyraldehyde in PET, into food simulants under conditions of changing pH and solvents, such as those observed in fermented foods like kimchi or sauerkraut. Methods: Using a migration model based on Fick's second law of diffusion in one dimension, the migration of acetaldehyde and butyraldehyde from PET into a simulant of fermented food at $20^{\circ}C$ over 10 days was evaluated. The simulant for fermented food was modelled as 10% ethanol for three days, followed by 3% acetic acid for seven days. Results: The migration of acetaldehyde into the 10% ethanol was 0.36 times that of a simulated fermented food system, while that of butyraldehyde was 1.34 times greater. These results may have been influenced by the chemical interactions among the migrants, polymers and simulants, as well as by the solubilities of the migrants in polymers and simulants. Conclusion: Because food simulants have a limited capacity to mimic real food systems under the current migration model, an appropriate simulant and migration test should be considered in the case of increasing acidity. Furthermore, since the accuracy of the worst-case estimation of migration predicted by the current model is severely limited under changing food conditions, food simulants and their interactions should be further investigated with respect to conservative migration modelling.

• Applied Biological Chemistry
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• 제31권1호
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• pp.13-20
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• 1988

쌀보리(무안보리, 송학, 새쌀보리 및 늘쌀보리)를 입자 크기별로 분류하고 $40^{\circ}C$에서의 수분 흡수 특성을 비교하였다. 쌀보리의 주를 이루는 입자는 7mesh이었고 다음이 10mesh로서 이들 입자는 무안보리는 86% 나머지는 $91{\sim}94%$를 차지하였다. 입자의 길이, 폭, 부피, 표면적 및 무게는 입자크기가 작아질수록 작아졌으나 길이와 폭의 비는 반대로 증가하였다. 쌀보리의 침지 중 수분 증가량은 입자가 작아질수록 증가하였다. 쌀보리의 주를 이루는 7mesh입자의 경우 수분증가량은 늘쌀보리, 송학, 새쌀보리, 무안보리의 순서이었으며 시료 모두 침지시간 35시간에 평형 수분함량에 도달하였다. 쌀보리의 확산계수는 입자가 작아질수록 증가하였으나 6 및 7mesh입자는 서로 비슷한 값을 보였다. 쌀보리의 침지 중 부피증가량은 수분증가량과 직선적인 관계를 보였다.

• Journal of Biosystems Engineering
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• 제27권3호
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• pp.219-226
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• 2002

Desorption equilibrium moisture contents of oak mushroom were measured by the static method using salt solutions at flour temperature levels of 35$\^{C}$, 45$\^{C}$, 55$\^{C}$ and 6$\^{C}$ and five relative humidity levels in the range from 11.0% to 90.8%. EMC data were fitted to the modified Henderson, Chung-Pfost, modified Halsey and modified Oswin models using nonlinear regression analysis. Drying tests far oak mushroom were conducted in an experimental dryer equipped with air conditioning unit. The drying test were performed in triplicate at flour air temperatures of 35$\^{C}$, 45$\^{C}$, 55$\^{C}$ and 65$\^{C}$ and three relative humidities of 30%, 50% and 70% respectively. Measured moisture ratio data were fitted to the selected four drying models(Lewis, Page, simplified diffusion and Thompson models) using stepwise multiple regression analysis. The results of comparing root mean square errors for EMC models showed that modified Halsey was the best model, and modified Oswin models could be available far oak mushroom. The results of comparing coefficients of determination and root mean square errors of moisture ratio for four drying models showed that Page model were found to fit adequately to all drying test data with a coefficient of determination of 0.9990 and root mean square error of moisture ratio of 0.00739.

• 한국주조공학회지
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• 제27권6호
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• pp.243-249
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• 2007

The effect of Re addition and solidification rate on the directional solidification behavior of Ni-Al model alloy has been investigated. Directional solidification (DS) were carried out using the modified Bridgman furnace with various solidification rates. The solid/liquid interface during directional solidification was preserved by quenching the specimen after the desired volume fraction of original liquid was solidified. The equilibrium partition coefficients of Al and Re Were estimated by measuring the compositions at the quenched solid/liquid interface. Then, the effect of Re addition on the elemental segregation behavior was carefully analyzed. The differential scanning calorimetry results showed that the Re addition results in increased ${\gamma}'$ solvus and freezing range of the alloy. It was also shown that the primary dendrite arm spacing gradually decreases with increasing the Re content, while the secondary dendrite arm spacing appears to be independent on the Re content. The compositional analyses clearly revealed that the segregation of Al increased with increasing the Re content and solidification rate, while that of Re was found to be independent on the solidification rate in the range of $10{\sim}100{\mu}m/s$ due to its sluggish diffusion rate in the Ni solid solution.

• 한국물환경학회지
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• 제28권2호
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• pp.292-299
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• 2012

The objective of this study is to develop a novel method for evaluating forward osmosis (FO) membrane performances using a non-pressurized FO system. Basic membrane performance parameters including water (A) and solute (B) permeability coefficients and unique parameter for FO membrane such as the support layer structural parameter (S) were determined in two FO modes (i.e., active layer faces feed solution (AL-FS) and active layer faces draw solution (AL-DS)). Futhermore, these parameters were compared with those determined in a pressurized reverse osmosis (RO) system. Theoretical water flux was calculated by employing these parameters to a model that accounts for the effects of both internal and external concentration polarization. Water flux from FO experiment was compared to theoretical water fluxes for assessing the reliability of those parameters determined in three different operation modes (i.e., AL-FS FO, AL-DS FO, and RO modes). It is demonstrated that FO membrane performance parameters can be accurately measured in non-pressurized FO mode. Specifically, membrane performance parameters determined in AL-DS FO mode most accurately predict FO water flux. This implies that the evaluation of FO membrane performances should be performed in non-pressurized FO mode, which can prevent membrane compaction and/or defect and more precisely reflect FO operation conditions.

• 대한기계학회논문집B
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• 제28권1호
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• pp.24-30
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• 2004

Analysis model for the two-phase catalytic reactor is presented. With the progress in development of micro thermofluidic devices, needs fur understanding of the phenomena in two phase reaction in cm scale has been arisen. To investigate thermal and reactive performance of down scaled two phase reactor simple analysis model that is a kind of lumped flow model is proposed. Analysis model presented is based on the experiment on mm scale model reactor. Target experiment is catalytic decomposition of 70wt％ hydrogen peroxide with existence of perovskite L $a_{0.8}$S $r_{0.2}$Co $O_3$ catalyst. It is composed of balance equations of mass and energy. Each phase is considered to be a species fur the simplicity. Axial diffusion and transversal distribution of properties are neglected. Two phase catalytic reaction is modeled as successive gasification of liquid lump around catalyst and reaction in gas phase. Heat transfer is modeled by model function ofNu number. Modeled Nu is expressed as Nu=N $u_{0}$ (1＋ $a_1$( $a_2$ $T^{-}$ $a_3$)exp( $a_4$ $T^{-1}$)exp( $a_{5}$ z). Transfer coefficients are determined by the comparison of experimental results. With the model, heat transfer characteristics are investigated. Also by the mass transfer coefficient, characteristics in mass transfer is investigated. With the result basic understanding on design and analysis of mm scale two-phase reactive device is obtained. Also it can be further applied to micro scale reactive device fabricated by micromachining.ing..

• Korean Chemical Engineering Research
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• 제58권2호
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• pp.171-175
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• 2020

고분자전해질 연료전지(PEMFC)에서 지지체에 의해 내구성을 향상시킨 강화막(Reinforced Membrane)의 개발이 국내에서 활발히 진행되고 있다. 본 연구에서는 4 종류의 강화막의 초기 성능 및 특성을 비교하였다. 고분자막의 C-F사슬의 양이 더 많은 강화막이 C-F사슬의 소수성 때문에 물 확산계수가 더 작음을 보였다. 고분자막 두께가 두꺼울수록 수소투과도가 감소하고 OCV가 증가함을 확인하였다. Short 저항이 1.5 Ωcm² 이하인 막은 OCV가 0.9 V이하이고 성능도 최저여서 Short 저항이 3.0 Ωcm² 이상이어야 함을 보였다. 현재 기준이 되는 국외 막과 비교했을 때 비슷한 국내 막도 있어서 PEMFC 고분자막의 국산화 가능성을 확인할 수 있었다.

• 대한화학회지
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• 제45권5호
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• pp.429-435
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• 2001

단량체인 N,N'-bis(2-pyrrol-1-yl-propyl)-4,4'-bipyridine(bpb)을 유리탄소전극 상에 전기화학적으로 중합한 고분자 피막전극을 erichrome black T(EBT) 와 glutathione(GSSG)의 1:1 용액으로 수식하여 GC/poly-bpb, EBT, GSSG형의 전극을 제작하고 이로써 Zn(II)을 포집한 전극을 제작하였다. 수식된 피막 내에서 이온의 확산계수는 아연이온이 포집되기 전후에 각각 2.43${\times}10^{-15}$과 9.14${\times}10^{-15}cm^2s^{-1}$으로 피막내의 전기화학적 활성자리에서 이탈이 거의 일어나지 않는 안정한 전극이다. 중합된 bpb의 양이 2.83${\times}10^4gmol^{-1}$에 대하여 1.17${\times}10^4gmol^{-1}$의 아연이온이 포집되었다. 이들 중에 산화-환원 과정에서 회합/해리에 관여하는 이온은 포집된 180개의 이온들 중에서 81.7%였다. 이는 EBT 만으로 수식된 전극에서 보다 3배정도 큰 값이다.

• 한국해양학회지
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• 제30권4호
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• pp.288-301
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• 1995

적도 태평양 클라리온-클리퍼톤 균열대 사이의 한국심해 연구(KODOS)지역에서 채 취된 3개의 퇴적물 코아에 우라늄계열 비평형 기법을 적용하여 퇴적율과 입자교란율이 추정되었다. 과잉 토륨-230 방사능과 과잉 토륨-230/토륨-232 방사능비의 수직분포로 부터 추정된 퇴적율은 연구지역의 남동부 지역에서 천년 동안 수 밀리미터로 추정되었 으며, 북서부에서는 천년당 일 밀리미터 이하로 추정되었다. 퇴적물 시료의 방수에서 과잉 토륨-230 방사능과 과잉 토륨-230/토륨-232 방사능비가 일정한 수직분포를 보이 며 이는 저서생물등에 의한 입자 교란작용의 영향인 것으로 사료된다. 과잉 납-210의 수직농도 분포를 근거로 퇴적물 상부층과 하부층의 입자교란 속도를 추정하기 위하여 "2상자" 이류-확산 입자혼합 모델을 이용하였다. 입자혼합계수는 상부층에서는 수 10$cm^2$/y이며 하부층에서는 일 내지 수 $cm^2$/y로 추정되었다./y로 추정되었다.