• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.3-7
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• 1996

A rigorous analysis on the effect of colloidal interactions on the separation characteristic has been extended to the case of non-dilute charged solute concentration. The solute partitioning within slit pores for a wide range of solute concentration has been predicted by performing the Monte Carlo technique. Using a hindered transport model, rejection coefficients have been estimated from the predicted concentration profile.

• Journal of the Korean Home Economics Association
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• v.46 no.9
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• pp.61-69
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• 2008

The purpose of this study was to investigate similarities in behavioral characteristics between children and their friends. Aggression and withdrawal behaviors, in conjunction with the effects of friendship quality and characteristics on peer rejection were analyzed. The participants were 414 fifth and sixth grade primary school children recruited from public schools in Bucheon city. Firstly, the peer nomination index was used to assess aggression, withdrawal, and peer rejection. Secondly, children reported on the quality of their friendships using the Friendship Quality Scale. The results indicates similarities in aggression and withdrawal between children and friends. Friends' aggression and withdrawal characteristics predicted children's peer rejection, which was more pronounced with higher friendship quality.

• Membrane and Water Treatment
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• v.3 no.2
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• pp.77-98
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• 2012

A two-dimensional (2D) steady state numerical model of concentration polarisation (CP) phenomena in a membrane channel has been developed using the commercially available computational fluid dynamics (CFD) package CFX (Ansys, Inc., USA). The model incorporates the transmembrane pressure (TMP), axially variable permeate flux, variable diffusivity and viscosity, and osmotic pressure effects. The model has been verified against several benchmark analytical and empirical solutions from the membrane literature. Additionally, the model is able to predict the rejection of an arbitrary solute by the membrane using a pore model, given some basic knowledge of the geometry of the solute molecule or particle, and the membrane pore geometry. This allows for predictive design of membrane systems without experimental determination of the membrane rejection for the specified operating conditions. A demonstration of the model is presented against experimental results for two uncharged test compounds (sucrose and PEG1000) from the literature. The model will be extended to incorporate charge effects, transient simulations, three-dimensional (3D) geometry and turbulent effects in future work.

• Journal of the Korean Chemical Society
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• v.63 no.4
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• pp.260-265
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• 2019

Alcohol dehydrogenase (ADH) (EC 1.1.1.1) was selected as the enzyme which will be immobilized on ultrafiltration membrane by fouling with different transmembrane pressure of 1, 2 and 3 bars. ADH will catalyze formaldehyde (CHOH) to methanol ($CH_3OH$) and simultaneously oxidized nicotinamide adenine dinucleotide (NADH) to $NAD^+$. The concentration of enzyme and pH are fixed at 0.1 mg/ml and pH 7.0 respectively. The objective of the study focuses on the effect of different transmembrane pressure (TMP) on enzyme immobilization in term of permeate flux, observed rejection, enzyme loading and fouling mechanism. The results showed that at 1 bar holds the lowest enzyme loading which is 1.085 mg while 2 bar holds the highest enzyme loading which is 1.357 mg out of 3.0 mg as the initial enzyme feed. The permeate flux for each TMP decreased with increasing cumulative permeate volume. The observed rejection is linearly correlated with the TMP where increase in TMP will cause a higher observed rejection. Hermia model predicted that at irreversible fouling with standard blocking dominates at TMP of 3 bar, while cake layer and intermediate blocking dominates at 1 and 2 bar respectively.

• Membrane and Water Treatment
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• v.7 no.4
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• pp.327-339
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• 2016

Nanofiltration is useful to concentrate propolis extract. During the selection of membrane, both compound rejection and permeate flux are important indicators of process economy. Brazilian green propolis extract was studied to evaluate the separation performance of Startmen 122 and NF270 membranes. Compared to Starmen 122, NF270 membrane showed better rejection of bioactive compounds. The flux decline patterns were further studied using Hermia's model. Cake formation is the major fouling mechanism on the hydrophobic surface of Starmen 122. While the fouling mechanism for NF270 is pore blocking. The fouled membranes were further characterized using SEM and FT-IR to confirm on the predicted fouling mechanisms.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.140-142
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• 2007

This paper presents an effective method of precise velocity control at low speed with a low resolution encoder. Multirate observer to estimate the velocity at every DSP control period is used except a constant velocity mode. The observer corrects the estimation error when detects pulse signal. Unlike the conventional methods, the multirate estimator is stable at a low speed. However, the multirate estimator shows ripples at a constant velocity. Thus, in this paper we use a velocity prediction method which uses the present velocity from the previous average velocity to reject the ripple. In a summary, at a constant speed mode, the predicted velocity is used. Otherwise, the estimated velocity by the multirate obvserver is used. The effectiveness of the multirate observer and ripple rejection at low speed is verified through various simulations.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.563-567
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• 1999

Reverse osmosis concentration for cephalosproin C was studied using a polyamide composite membrane, FT-30 in spiral wound type with high solute rejection. The experiments were carried out in the aqueous solution of cephalosporin C for water flux, solute rejection and mass transfer coefficient under applied pressure of $4{\sim}20kg/cm^2$, feed concentration of 100~1000 mg/L and feed velocity of 2.8 and 5.6 L/min at room temperature. The effect of operating pressure on the separation of cephalosporin C showed that permeate flux increased with increasing operation pressure. These results are consistent with those predicted by Kedem-Katchalsky model. Solute rejection was nearly 1. The increase of feed concentration caused the reduction of cephalosporin C rejection, which was higher at low concentration than at high concentration, but degree of reduction was small.

• Korean Journal of Child Studies
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• v.20 no.3
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• pp.107-121
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• 1999

This hypothesis of this study was that individual risk variables (behavior problems) compounded by social risk variables (peer rejection) would place children at risk for victimization by peers. Subjects were 385 boys and girls in 3rd and 5th grade. Data were collected with questionnaires. As predicted, behavior problems (both internalizing and externalizing) were more strongly related to victimization when children were rejected by peers than when they were accepted. These results illustrate the principle that individual risk variables depend on social context.

• Korean Journal of Child Studies
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• v.17 no.1
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• pp.189-212
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• 1996

The purpose of this study was to investigate how parental childrearing behavior and children's sibling relationships are related to children's self-esteem. 440 middle class families consisting of two children and their parents were the subjects of this study. The research instruments included a childrearing behavior questionnaire, the Sibling Relationships Questionnaire (Furman & Buhrmester, 1985), and the Self-Perception Profile for Children (Harter, 1985). Analyses of the data included correlation analysis, canonical correlation, regression, stepwise multiple regression, and MANOVA with stepwise discriminant analysis as the follow-up test. The most powerful predictors of children's self-esteem were the Warmth-Acceptance of childrearing behavior and the Warmth-Closeness of sibling relationships. The self-esteem dimension was best predicted by parental childrearing behavior and by children's sibling relationships was Global Self-Worth. Behavioral Conduct was best predicted by the Rejection-Restriction factor of childrearing, and by Conflict (for boys) and Rivalry (for girls) factors of sibling relationships. Children's self-esteem was related more strongly to the Warmth-Acceptance and the Rejection-Restriction of opposite-sex parents. The effects of Permissiveness-Nonintervention were stronger in same-sex parent-child dyads. Parental childrearing behaviors accounted for boy's self-esteem better than girl's with the exception of Behavioral Conduct. Sibling relationships accounted for girl's self-esteem better than boy's. The $2{\times}2$ MANOVA revealed interaction effects of parental childrearing behaviors and sibling relationships on children's self-esteem. Two factors of Rivalry and Conflict in sibling relationships and all three factors of childrearing behaviors showed significant interaction effects, The childrearing factor of Permissiveness-Nonintervention and the sibling factor of Rivalry, which were relatively weak predictors of self-esteem when acting alone, gained power in explaining children's self-esteem within the interactional context.

• Nuclear Engineering and Technology
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• v.33 no.3
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• pp.339-348
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• 2001

NSSS Control Systems automatically mitigate transient conditions and leads to a stable plant condition without operator actions when a transient occurs during normal power operation. In this paper, the function and performance of NSSS control systems were examined and evaluated by comparing the predicted results with the measured data for the selected events. Loss of a Main Feedwater Pump and Load Rejection to House Load Operation events were selected for the evaluation among the transient tests peformed during the Power Ascension Test (PAT) of UCN unit 4. The overall schematic control actions of NSSS control systems can be evaluated easily through the observation of these two typical events. The selected events were analyzed by the KISPAC computer code[l] which had been used in developing the control logic and determining the control setpoints during the plant design. Additionally, the performance of FWCS during low power operation was evaluated. The result of evaluation showed that the NSSS control systems were designed properly and the performance of the NSSS control systems was excellent and also the computer code had a good prediction capability.