• Korean Chemical Engineering Research
• /
• v.47 no.1
• /
• pp.38-45
• /
• 2009

In this study, interfacial properties were measured for imidazoline type cationic surfactant system which has been widely used as a fabric softener, a dispersant, an anti-static agent, a bleach activator, and an emulsifier. The CMC of imidazoline surfactant was near $6{\times}10^{-5}mol/L$ and the surface tension at CMC was about 32 mN/m. It was found that surface tension was not affected by surfactant concentration but decreased with an increase in pH. The interfacial tension between 1 wt% aqueous solution and n-dodecane was shown to be about 0.01 mN/m and equilibration time was not affected by pH. Phase behavior experiment in a binary aqueous surfactant system showed that only micellar solution of $L_1$ phase was found under conditions of temperature and pH investigated during this study. Only a two-phase region consisting of lower-phase microemulsion in equilibrium with excess oil phase existed under the same conditions, when oil was added to the binary surfactant system. The foam stability measured with 1 wt% surfactant solution increased with pH, which is consistent with surface tension measurement result. QCM(quartz crystal microbalance) measurement showed that surfactant adsorption increased with surfactant concentration but decreased with pH. According to the friction measurement, best fabric softening effect by imidazoline surfactant system was found under alkali conditions.

• Korean Chemical Engineering Research
• /
• v.50 no.3
• /
• pp.455-463
• /
• 2012

In this study, the measurement of physical properties of ethylene oxide-propylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of DEP-OSA82-AO zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that DEP32-OSA82-AO and DEP34-OSA82-AO surfactants provide better softening effect at a pH of acidic or neutral condition than at an alkaline condition. This result indicates that both surfactants act as a cationic surfactant at a pH of acidic or neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.

• Science of Emotion and Sensibility
• /
• v.21 no.2
• /
• pp.89-100
• /
• 2018

This study was performed to develop face towel fabrics that reflect consumer's tactile preferences. Three different kinds of pile fiber (100% cotton, 50% cotton/50% bamboo, 100% bamboo) of the towel fabrics were selected for the test. The towels were laundered one, five and 10 times repeatedly in a normal washing condition, and fabric softeners were applied to the towels that were laundered 10 times. The flexibility and absorbency (absorption rate and water absorptivity) were evaluated by laundering times of the face towels. Male and female university students evaluated their subjective sensations of the face towels. The flexibility of towel fabrics showed no significant difference according to type of pile fiber or laundering time. The absorbency of the towels was significantly different according to the type of pile fiber and laundering time. The absorption rate was higher in 100% bamboo fiber, and water absorptivity was higher for cotton fibers. There were no significant differences in subjective sensation according to the type of pile fiber of towels before laundering. As the frequency of laundering increased, the tactile preference for the towel slightly decreased. The 100% bamboo towel was rated the most comfortable among the three kinds of towels. The tactile preference for the towels was influenced by smoothness, fabric softness, and softener treatment, in that order.

• Journal of Adhesion and Interface
• /
• v.24 no.2
• /
• pp.54-59
• /
• 2023

Silver nanowire-based transparent electrodes are very attractive as a next-generation flexible and transparent electrode that can replace ITO-based flexible electrodes because they have excellent conductivity, transmittance and mechanical flexibility. However, weak understanding of the silver nanowire solution for the fabrication of silver nanowire-based transparent electrodes often cause abnormal operation of the electrical device or peeling problem of the electrode films when applied to electronic devices. Here, we studied a Hydroxypropyl Methylcellulose (HPMC) adhesion promoter, which is one of the additives for silver nanowire solution, to improve the understanding of silver nanowire solution. In detail, it is characterized how the HPMC changes the properties of silver nanowire solution and silver nanowire film, which is fabricated with silver nanowire solution including the HPMC adhesion promoter. As the characteristics of solution, polar surface tension and dispersive surface tension were measured. As the film characteristics, surface energy, surface morphology, silver nanowire density, and sheet resistance were analyzed.

• 대학교육
• /
• s.94
• /
• pp.56-63
• /
• 1998

학점은행제는 '98년 봄학기부터 최초로 실시되면서 몇가지 문제점들을 보이고 있다. 즉, 실시기관 선정에 따른 문제, 저조한 지원율, 학점은행제 운영기관의 재정적 부담, 교과목 연결 체계의 미흡, 기관마다 다른 수강료 등이 그것이다. 또한 시행기관수의 부족, 개설 교과목 부족, 졸업까지 너무 긴 시간이 소요된다는 점도 예상되는 문제점이다. 이들을 개선하기 위해서는 주말 강의나 계절학기제 도입, 실시기관의 컨소시엄 형태 운영, 유연한 운영체제 확립 등이 요구된다.

• Resources Recycling
• /
• v.5 no.3
• /
• pp.44-49
• /
• 1996

One of the most serious problems in utilizing the fly-ash produced from damcstic coal-firing power plants is lhc unburned-carbon mntained m the fly-ash In this shldy, the effects of fruther and collector an the yield,recuvery,unburnedcarbon rejectiou peiccntage,and process efficiency of product (cleaned fly-ash) wcrc examined when convzntional froth flotation was applied to rejcct the unburned-carbon included in the fly-ash of bituminous coal Alsa,the ash analysis for both thc raw and the clcaned fly-ash was conducted to review the change in thc major elements of fly-ash. Experimental results shawcd lhat tlle rcjectlon oI the unburned-cubon of thc raw fly-ash sample is available upto 92.4% using fiath flotalian and that the putity ol the pmdud(c1eancd fly-ash) attains up to 99.4%.

• Journal of the Korean Chemical Society
• /
• v.45 no.4
• /
• pp.334-340
• /
• 2001

The water soluble carboxymethyl-chitin (CM-chitin) has been well known to be very useful to the cosmetic field as a moisturizer, a smoothener, a cell activater and a cleaner for face skin conditioning. In this study, the preparation process of CM-chitin was simplified with elimination of some procedures in the conventional method. The chitin powder was mixed with sodium hydroxide solution. And then a mixture of sodium monochloroacetate (or monochloroacetic acid) and isopropyl alcohol (or a mixed solution with water and isopropyl alcohol) was added to thorough the agitation and the freezing during 16 hours. The CM-chitin with a high degree of substitution by the improved process was obtained.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.11
• /
• pp.1423-1428
• /
• 2011

This paper proposes a learning input shaper with nonlinear actuator dynamics to reduce the residual vibration of flexible systems. The controller is composed of an estimator of the time constant of the nonlinear actuator dynamics, a recursive least squares method, and an iterative updating algorithm. The updating mechanism is modified by introducing a vibration measurement function to cope with the dynamics of nonlinear actuators. The controller is numerically evaluated with respect to parameter convergence and control performance by using a benchmark pendulum system. The feasibility and applicability of the controller are demonstrated by comparing its control performance to that of an existing controller algorithm.

• Applied Chemistry for Engineering
• /
• v.20 no.5
• /
• pp.479-485
• /
• 2009

In this study, basic physical properties were measured for ASCO EQ85 cationic surfactant of triethanolamine-ester quaternary ammonium salt and effect of pH on softening performance on fabrics was investigated using zeta potential measurement and adsorption experiment by quartz crystal microbalance. The CMC of the surfactant was near $3{\times}10^{-3}mol/L$ and the surface tension at CMC was about 40 mN/m. The interfacial tension measurement between 1 wt% aqueous solution and n-dodecane measured by spinning drop tensiometer showed that interfacial tension slightly increased with an increase in pH but the equilibration time was not affected by pH. The surfactant adsorption was found to increase with an increase in surfactant concentration and was also affected by pH of surfactant solution. The friction factor for fabrics treated with ASCO EQ85 surfactant was shown to increase with pH and better softening effect was found under acidic conditions. Half-life for foams generated with ASCO EQ85 surfactant solution increased with pH, which indicated an increase in foam stability with pH.

• Journal of Families and Better Life
• /
• v.30 no.2
• /
• pp.173-187
• /
• 2012

This qualitative case study focused on the activation plan of flexible work arrangements. We selected eight workers from a foreign affiliated firm that has various flexible work arrangements for in-depth interview and focus group interview. The workers were categorized into two groups; those who have experiences with flexible working and those who have needs for flexible working. We analyzed their condition of work-family life and experiences with flexible working. Through the focus group interview, we can find out the needs and suggestions about activation plans of flexible work arrangements.