• Title/Summary/Keyword: Physical separation

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Development of Flow Visualization Device with Smoke Generator in Learning Wind Tunnel (학습용 풍동의 연기 유동가시화 장치 개발)

  • Lim, Chang-Su;Choi, Jun-Seop
    • 대한공업교육학회지
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    • v.32 no.2
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    • pp.87-103
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    • 2007
  • The purpose of this study was to develop of the smoke flow visualization device of learning wind tunnel, teaching-learning materials in order to demonstrate air-flow around the fluid-flow field qualitatively and understand the resistance concepts of fluid-flow in secondary school. The contents of this study were consisted of the development and experiment of smoke flow visualization for learning wind tunnel. The main results of this study were as follows: First, this developed teaching-learning material here will help students understand the fundamental physical phenomena related with the resistance of fluid and the various patterns of air-flow in the field of transportation technology. Second, flow visualization has shown the same tendency in both of theoretical and experimental patterns. Third, the airfoil model has the smallest wake region meaning resistance against air-flow of circular cylinder and square rod model. Forth, flow separation point at leading edge and wide wake region began to show under the angle of attack of airfoil model ${\alpha}$ is $20^{\circ}$. Fifth, the wake width of the flow field behind a golf ball with dimple became slightly narrower than that without dimple. Sixth, the developed device was made to apply the teaching and learning materials for the experiment and practice in order to increase students' interest and attitude.

Usability Study of the Elderly Women Using Indoor Driving and Elevating Electric Wheelchairs (실내 주행 및 승강 전동 휠체어를 이용하는 고령 여성의 사용성 연구)

  • Kim, Young-Pil;Hong, Jae-Soo;Ham, Hun-Ju;Hong, Sung-Hee;Ko, Seok-Cheol
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.7
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    • pp.419-427
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    • 2020
  • This study was undertaken to address the difficulties and inconveniences of an electric wheelchair. We focused on improving usability of initially completed products by augmenting the prototypes designed in the previous study. For evaluation of usability, 10 elderly women aged over 65 years, capable of movements and physical activities in daily life, were enrolled as subjects. The experimental method included a subjective satisfaction questionnaire evaluation of the elderly women using the target product, and the observation evaluation was achieved using video recording data, etc. Usability evaluation revealed that the elevating sector requires improvement of intuition through separation of the elevating control panel and the driving control panel. Improvements in the driving sector include corrections of the front wheel mechanism or driving control algorithm, UI, and sudden stop system. Transferring section assessment revealed a necessity to secure structures and add structures that support power. We believe that based on the inconveniences and improvements presented in the usability evaluation, appending the existing prototype with complementary products will improve the quality of life of elderly women with limited mobility.

Lipase-Catalyzed Reactions for Fats and Oils in Non-Polar Solvent (유기용매 내에서의 유지의 리파제 촉매반응)

  • Daeseok Han;Kwon, Dae-Young;Rhee, Joon-Shick
    • Microbiology and Biotechnology Letters
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    • v.16 no.3
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    • pp.250-258
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    • 1988
  • Lipases are well known as the enzymes which catalyze the hydrolysis of ester bonds combining aliphatic chains and glycerol on mono-, di- and triglycerides. Their reactions are characterized by be-ing heterogeneous and catalyzing the water-insoluble substrates. This property has been one of the Hurdles which delayed the application of lipases in fats and oils industry, However, with the development of biological reaction system of which organic solvent is introduced in part or whole as the reaction media, enzymatic manipulation of fats and oils is attracting increasing attention from the academic and industrial sectors. Trials in two-phase system and reversed micellar system to produce fatty acids through enzymatic hydrolysis of triglycerides preyed to be efficient in respect to volumetric productivity, fat hydrolysis rate, product separation, etc. In organic solvent system lipases have been found to have the ability to catalyze aminolysis, transesterification, esterification, thiotransesterification and oximolysis that are virtually impossible to catalyze in water. The organic solvent system is being extensively used in interesterifying glycerides to produce a fat with the modified physical and chemical nature.

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Architecture and Transport Properties of Membranes out of Graphene (그래핀에 기초한 막의 구조와 물질 전달 성질 개관)

  • Buchheim, Jakob;Wyss, Roman M.;Kim, Chang-Min;Deng, Mengmeng;Park, Hyung Gyu
    • Membrane Journal
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    • v.26 no.4
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    • pp.239-252
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    • 2016
  • Two-dimensional materials offer unique characteristics for membrane applications to water technology. With its atomic thickness, availability and stackability, graphene in particular is attracting attention in the research and industrial communities. Here, we present a brief overview of the recent research activities in this rising topic with bringing two membrane architecture into focus. Pristine graphene in single- and polycrystallinity poses a unique diffusion barrier property for most of chemical species at broad ambient conditions. If well designed and controlled, physical and chemical perforation can turn this barrier layer to a thinnest feasible membrane that permits ultimate permeation at given pore sizes. For subcontinuum pores, both molecular dynamics simulations and experiments predict potential salt rejection to envisage a seawater desalination application. Another novel membrane architecture is a stack of individual layers of 2D materials. When graphene-based platelets are chemically modified and stacked, the interplanar spacing forms a narrow transport pathway capable of separation of solvated ions from pure water. Bearing unbeknownst permeance and selectivity, both membrane architecture - ultrathin porous graphene and stacked platelets - offer a promising prospect for new extraordinary membranes for water technology applications.

Exploration on Modern People's Emotion regarding Abolition of Racing Model (레이싱 모델 폐지에 관한 현대인의 감성 탐색)

  • Jung, Sang-Pil
    • Journal of Digital Convergence
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    • v.18 no.11
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    • pp.571-579
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    • 2020
  • The purpose of the study was to explore modern people's emotion regarding sex commercialization related to the abolition of grid girl. To collect data, based on 'reply journalism', this study collected 15 blogs, 10 online cafe contents, 1 youtube video clip, and 364 replies associated with the three online contents. To analyze the data, interpretive text analysis was utilized and the following results were obtained. As results, the analysis on the replies shows that the most strong emotion of the modern people regarding the abolition of grid girl is anti-feminism that includes hatred toward feminists and even females, criticism on feminism, and notion of 'women's enemy is women themselves'. In addition, sympathy toward racing models who lost their jobs, requirement of same abolition to the people with similar occupations, spatial separation between men and women, and consent on the abolition of racing models were found. Unlike the feminists' emotion regarding sex commercialization and racing models, modern people's emotion was different from them. Rather, ordinary people have doubted and even criticized on the rationales of feminism. Unlike feminists' notion about sex commercialization of racing models, these results imply that social image of racing models has changed and wish their position is respected as an ordinary occupation, without issues of sex commercialization.

The Effect of Ionic Group and MMA Contents on the Physical Properties of PU/PMMA Hybrids (PU/PMMA Hybrids의 물성에 대한 이온성기와 MMA함량의 영향)

  • Jeong, Chang Nam;Cho, Hang Kyu;Noh, Si Tae
    • Applied Chemistry for Engineering
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    • v.8 no.4
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    • pp.575-581
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    • 1997
  • UDs were synthesized from two different polyols(PTMG, PBEAG), ionic chain extender(DMPA), EDA with $H_{12}-MDI$. PU/PMMA hybrids were prepared with free radical polymerization of MMA monomer in MMA-swelled PUD. PUD particle size and film properties were investigated ionic content and polyol type. Mechanical and thermal properties of PU/PMMA hybrid film were studied in terms of PU's ionic content and the venation of PU/PMMA compositions. As DMPA content increased from 2wt% to 10wt% in PUD, particle size of PUD decreased. PUD's particle size with ester type polyol was found to be smaller then ether type polyol used. Phase separation between hard segment(HS) and soft segment(SS) with ionic contents in PU was shown by the thermal, mechanical property measurement. Although the composition of MMA was changed from 0 to 40 wt% in PU/PMMA hybrid, the particle size of the hybrid did not increase. Using the ester type polyol, tensile strength of hybrid was found to increase by 2wt% - 6wt% DPMA content, but as higher content the strength of hybrid decreased. Moreover with the ether type polyol, tensile strength of hybrid was observed to increase by 2wt% - 4wt% DMPA content, while decreasing at higher content. PU and PMMA polymer molecule being mixed in molecular level was confirmed from the pattern of $T_g$ in DSC thermogram.

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The Experience of Parents Whose Child is Dying with Cancer (암 환아 부모의 경험에 대한 질적 연구)

  • ;;Ida Martinson
    • Journal of Korean Academy of Nursing
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    • v.22 no.4
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    • pp.491-505
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    • 1992
  • The purpose of this research was to understand the structure of the lived experience of parents of a child terminally ill with cancer The research question was “What is the structure of the experience of parents of a child terminally ill with cancer\ulcorner” The sample consisted of 17 parents of children admitted to the cancer units of two university hospitals in Seoul. The unstructured interviews were carried out from October 10, 1991 through January 10, 1992. They were audio-recorded and analysed using Van Kaam's method. Parents ascribed the cause of the cancer to the mother's emotional imbalance during pregnancy, the mother's stress, failure to observe religious rites, food, the parent's sin, misfortune and pollution. The theme clusters were tension, fear and depression experienced during pregnancy, stress that children suffer from abusive parents, failure to observe religious activites, bad luck, and sins committed during a previous life. When the child suffered a recurrence of cancer, the parents experienced negative emotions, nervousness, sorrow. depression and death. The theme clusters were feelings of despair, helplessness, regret, guilt, insecurity, emptyness and apathy. The long struggle with cancer resulted in the loss of economic security, loss of psychological and physical well being, and social withdrawal. The theme clusters were the economic burden of medical cost, giving up treatment, debt, limited medical insurance coverage and blood transfusion. The loss of psychological well being included stress, lack of support systems, inability to carry out responsibilities, lack of trust of the medical ten family breakdown, inappropriate expression of emotion and not disclosing the diagnosis to the child. Physically the parents suffered fatigue, insomnia, loss of appetite, loss of weight, dizzness, headache, psychosomatic symptoms, and increased consumption of liquor and cigarettes. Social withdrawal was manifested by taking time off from work to look after the child, decrease of outside social activities and feelings of isolation. Influences on family life were spousal conflicts, negative response of siblings, separation of the family members and economic hardship. The theme clusters were blaming a spouse for the cause of the illness and disagreements, maladjustment, lonliness, hostility and depression of siblings. The high price of medical care over the long period was a major factor influencing the life of the family. Positive experiences during the child's long illness were the strengthening of support systems and religious beliefs and financial help from social organizations. The support of one's spouse primarily helped to overcome the stress of the long illness. In addition, support was received from parents of other children with cancer and from nurses and religious leaders. The nurse, by providing empathetic support, should be a person with whom parents can express their feelings and share their experiences.

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Local surface potential and current-voltage behaviors of $Cu(In,Ga)Se_2$ thin-films with different Ga/(In+Ga) content (Ga/(In+Ga) 함량비에 따른 $Cu(In,Ga)Se_2$ 박막의 국소적 영역에서의 표면 퍼텐셜과 전류-전압 특성 연구)

  • Kim, G.Y.;Jeong, A.R.;Jo, W.;Jo, H.J.;Kim, D.H.;Sung, S.J.;Hwang, D.K.;Kang, J.K.;Lee, D.H.
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.149-152
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    • 2012
  • $Cu(In,Ga)Se_2$ (CIGS) is one of the most promising photovoltaic materials because of large conversion efficiency which has been achieved with an optimum Ga/(In+Ga) composition in $CuIn_{1-x}Ga_xSe_2$ (X~0.3). The Ga/(In+Ga) content is important to determine band gap, solar cell performances and carrier behaviors at grain boundary (GB). Effects of Ga/(In+Ga) content on physical properties of the CIGS layers have been extensively studied. In previous research, it is reported that GB is not recombination center of CIGS thin-film solar cells. However, GB recombination and electron-hole pair behavior studies are still lacking, especially influence of with different X on CIGS thin-films. We obtained the GB surface potential, local current and I-V characteristic of different X (00.7 while X~0.3 showed higher potential than 100 mV on GBs. Higher potential on GBs appears positive band bending. It can decrease recombination loss because of carrier separation. Therefore, we suggest recombination and electron-hole behaviors at GBs depending on composition of X.

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Effects of Oxalic and L-ascorbic acids on Iron Removal form Iron-bearing Illite (일라이트 분체 내에 함유된 산화철 제거에 옥살산과 L-아스코르브산이 미치는 영향)

  • Lee, Won-Pyo;Kang, Il-Mo;Moon, Hi-Soo
    • Economic and Environmental Geology
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    • v.40 no.2 s.183
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    • pp.141-151
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    • 2007
  • This study was focused on iron removal from illite by L-ascorbic and oxalic acids. Iron has been shown as a secondary mineral such as iron oxides and hydroxides in illite ores. It is also known as a primary agent to degrade brightness index of the ores. Methods such as physical separation and chemical leaching with strong inorganic acids have been widely used to remove the iron from the ores. However, these methods are expensive and give rise to environmental problems. In this study, we examined an alternative method using solutions with different set of combination of sulfuric, hydrochloric, L-ascorbic, and oxalic acids. Compared to chemical treatments with only inorganic acids, our results demonstrate that an addition of L-ascorbic acid in inorganic acids results in decreasing both total concentrations of the inorganic acids and time for the treatments. The treatment with 0.15 M L-ascorbic acid and 0.25 M sulfuric acid in solution for 60 min significantly improved the brightness index from 42.4% to 74.4%. This improvement is similar to that of treatment with only 2.5 M sulfuric acid alone for 150 min. Mineralogical and chemical analyses were performed to compare the effect of acid leaching on illite powders. No obvious differences are observed in the mineralogical characteristics and particle size distributions of the samples. These results suggest that the treatment with the addition of L-ascorbic acid in sulfuric acid could effectively remove iron without modifying the physicochemical properties of illite under conditions used in this study.

Adsorption Equilibrium, Kinetics and Thermodynamic Parameters Studies of Bismarck Brown R Dye Adsorption on Granular Activated Carbon (입상 활성탄에 대한 비스마르크 브라운 R 염료의 흡착평형, 동력학 및 열역학 파라미터에 관한 연구)

  • Lee, Jong-Jib
    • Applied Chemistry for Engineering
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    • v.24 no.3
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    • pp.327-332
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    • 2013
  • Batch experiments were carried out for adsorption equilibrium, kinetics and thermodynamic parameters of the brilliant brown R onto granular activated carbon. The operating variables studied were the initial dye concentration, contact time and temperature. Experimental equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption isotherm by linear regression method. The equilibrium process was well described by Freundlich isotherm model and from the determined separation factor (1/n), granular activated carbon could be employed as an effective treatment for the removal of bismarck brown R. From kinetic experiments, the adsorption processes were found to confirm the pseudo second order model with a good correlation and the adsorption rate constant ($k_2$) increased with increasing adsorption temperature. Thermodynamic parameters like the activation energy, change of Gibbs free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption in the temperature range of 298~318 K. The activation energy was determined as 8.73 kJ/mol for 100 mg/L. It was found that the adsorption of bismarck brown R on the granular activated carbon was physical process. The negative Gibbs free energy change (${\Delta}G$ = -2.59~-4.92 kJ/mol) and the positive enthalpy change (${\Delta}H$ = +26.34 kJ/mol) are indicative of the spontaneous and endothermic nature of the adsorption process.