• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.969-979
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• 2012

In this study, the effects of cosurfactant on phase equilibrium and dynamic behavior were studied in systems containing nonylphenol ethoxylate (NP) surfactant solutions and nonpolar hydrocarbon oils. All the cosurfactants used during this study such as n-pentanol, n-octanol and n-decanol acted as a hydrophobic additive and the hydrophobic effect was found to increase with both increases in chain length and amount of addition of a cosurfactant. Dynamic behavior studies under hydrophilic conditions showed that the solubilization of hydrocarbon oil by NP micellar solution is controlled by an interface-controlled mechanism rather than a diffusion-controlled mechanism. Both spontaneous emulsification of water into oil phase and expansion of oil drop were observed under lipophilic conditions because of diffusion of surfactant and water into oil phase. Under conditions of a three phase region including a middle-phase microemulsion, both rapid solubilization and emulsification of oil into aqueous solutions were found mainly due to the existence of ultralow interfacial tension.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1021-1026
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• 2012

The transient mass transfer in a single droplet system consisting of 1-octanol (continuous phase)/aqueous succinic acid solution (dispersed phase) was investigated in the presence of chemical reaction, which is acid/anion exchange reaction of succinic acid and tri-n-octylamine (TOA). This succinic acid extraction by TOA can be considered to occur at the interface between organic and aqueous phase, that is, heterogeneous reaction system. The basic properties of the system such as viscosity, density, distribution coefficient, terminal velocity of droplet, and diffusion coefficient were measured experimentally or calculated theoretically, and used for theoretical calculation of characteristic parameters of mass transfer later. The effects of succinic acid concentration on the terminal velocity was negligible in the existence of TOA, although the terminal velocity increases with succinic acid concentration in the absence of TOA. On the contrary, the terminal velocity decreases with TOA concentration. While droplets falls through organic phase, the trajectory of droplets is observed to oscillate around its vertical path. A mass trnasfer cell was prepared to monitor the mass transfer behavior in a single droplet and used to measure the mean concentration of succinic acid inside droplet. The results are expressed with dimensionless parameters. Under 50 g/L succinic acid condition, the system with 0.1 mol/kg TOA showed that the molar flux decreases in proportion to the decrease of concentration gradient, while in the case of 0.5 mol/kg TOA Sh increases rapidly with time indicating the molar flux of succinic acid decreases relatively slowly compared to the decrease in concentration gradient.

• The Korean Journal of Petroleum Geology
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• v.7 no.1_2 s.8
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• pp.1-6
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• 1999

Natural gas hydrate, a solid compound of natural gas (mainly methane) and water in the low temperature and high pressure, is widely distributed in permafrost region and deep sea sediments. Gas hydrate stability field (GHSF), which corresponds to the conditions of a stable existence of solid gas hydrate without dissociation, depends on temperature, pressure, and composition of gas and interstitial water. Gas hydrate-saturated sediment are easily recognized by the bottom simulating reflector (BSR), a strong-amplitude sea bottom-mimic reflector in seismic profiles. It is known that BSR is associated with the basal boundary of the GHSF, The purpose of this study is to define the GHSF and its occurrence in the southwestern part of Ulleung Basin, East Sea. The hydrothermal gradient is measured using the expandable bathythermograph (XBT) and the geothermal gradient data are utilized from previous drilling results for the adjacent area. By the laboratory work using methane and NaCl $3.0 wt{\%}$ solution, it is shown that the equilibrium pressures of the gas hydrate reach to 2,920.2 kPa at 274.15 K and to 18,090 kPa at 289.95 K for the study area. Consequently, it is interpreted that the lower boundary of the GHSF is about 210 m beneath 400-m-deep sea bottom and about 480 m beneath 1,100-m-deep sea bottom. The resultant boundary is well matched with the depth of the BSR obtained from the seismic data analysis for the study area.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.41-48
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• 2004

We may consider the inducement of demand to public transportation as a solution to relieve traffic congestion and pollution. Subway has merits as moving on schedule, transporting more people than bus. But subway is required a vast investment in the early stage of construction has a huge debt. So it runs into red figures, and on this account, services of subway are falling more and more. Development of subway's operation cost function is useful to understand structure of subway's operation and catch the relations of operation cost and actual results. In addition, we can present the policy that is a helpful to the operation as development of operation cost function. But there are short of studies about operation cost deal with a subway comparison with local train. Because local train has many lines and data, on the other hand, subway has one to four lines and less data. Most of previous studies sought the operation cost function of Seoul. So this study aimed to develop and apply the operation cost function of Seoul, Incheon, Busan and Daegu area using full allocation method. In this study, we considered the number of passengers, track-km, train-km, revenue as actual results. By appling the operation cost function, we compared the average cost of each city and confirmed the existence of economies of scale about the number of passengers, train-km.

• Information Systems Review
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• v.11 no.1
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• pp.19-47
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• 2009

Many products today tend to adopt a convergence approach by adding new features or functionalities to the existing products. The convergence, however, results in both positive and negative effects on usage of products, and thus demonstrates the characteristics called "paradox of technology." On the one hand, the added functionalities or features will increase the usefulness of the products. On the other hand, the convergence increases complexity of learning and usage of products and may decrease satisfaction or user evaluations. This study provides an empirical evidence of this paradox through investigation of telematics, one of the exemplary products of convergence services. Our research model is designed to test the existence of the "paradox of technology" and includes variables such as variety of functions, complexity of usage, perceived usefulness, service evaluation, and service fit. The proposed research model and subsequent hypotheses are empirically tested using 149 survey responses from telematics users. We have found that the variety of functions is positively associated with perceived usefulness, but is negatively associated with the complexity of usage. The data analysis reveals that the perceived usefulness has more significant impacts on service evaluation than the complexity of usage does. Furthermore, the strength of causal relationships among these variables is partially moderated by the degree of service fit. This study thus highlights the paradox of technology in explaining user attitudes and beliefs associated with convergence services.

• Polymer(Korea)
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• v.27 no.5
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• pp.470-476
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• 2003

In order to obtain high refractive plastic materials, 1,2 -ethylenedisulfanylbis(2-mercaptomethyl-1-ethanthiol) (ESTT) was newly prepared in good yield by the reaction of 1,2-ethylenedisulfanylbis(2-bromomethyl-1-ethanthiol) (ESTB) with thiourea followed by hydrolysis using an aqueous ammonia solution and characterized by $^1$H-NMR (-SH at 1.7 ppm), $\^$13/C-NMR(-CH$_2$SH at 28.4 ppm) and FT-IR (-SH at 2540 cm$\^$-1/) spectroscopy, etc. Polythiourethanes (PTU) were obtained from the combinations of ESTT with each of 4,4＇-methylenebis(phenylisocyanate) (MDI), tolyene 2,4-diisocyanate (TDI), isophorone diisocyanate (IPDI), mxylene diisocyanate (XDI), and 1,6-diisocyanatohexane (HMDI) in the presence of dibutyltin dilaurylate as a catalyst, in a casting mold, and characterized by FT-IR (existence of N=C=O) spectroscopy and elemental analyzer (sulfur content). Accordingly, their thermal, mechanical and optical properties were investigated by using DSC, TGA, hardness tester and refractometer: both the melting point on DSC and crystallinity on X -ray diffraction (XRD) for specimens of PTUs were not observed. PTUs with T$\_$g/s above 110 $^{\circ}C$ showed good hardness (Shore D) in the range of 86 to 89. Thermal stabilities of PTUs obtained by using ESTT and each of diisocyanates containing aromatic rings were especially good. Also, the optical transmittances of amorphous PTUs through UV-visible source in the range of 400 to 600 nm were good. PTUs showed refractive indexes above 1.60, and their refractive indexes gradually increased with increase of sulfur contents.

• Research in Plant Disease
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• v.15 no.2
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• pp.68-71
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• 2009

Cucumber green mottle mosaic virus (CGMMV) was not infected in figleaf gourd by sap inoculation. However CGMMV was detected by RT-PCR from the figleaf gourd collected from a field growing cucumber grafted onto figleaf gourd in Cheonan, Chungcheongnam Province in 2008. Which field showed 100% infection rate of the virus disease. In the experiment grafted with cucumber onto figleaf gourd, transportation of CGMMV through cucumber to figleaf gourd was confirmed by RT-PCR when the virus was mechanically inoculated on the leaves of the cucumber. The amplified DNA concentration of the virus on electrophoresis gel was much higher in the cucumber than in the figleaf gourd. However, the virus particles from the figleaf gourds were not observed under electron microscopy, also sap of the figleaf gourds was not transmittable to Nicotiana benthamiana. To identify the existence of CGMMV particle, the virus was purified from figleaf gourd and cucumber growing together in the graft system. CGMMV solution extracted from the cucumber represented a typical absorption spectrum of the virus but that from the figleaf gourd did not. Only a few CGMMV particles were observed in the purified preparation from the figleaf gourd. These results confirmed that CGMMV only passed through figleaf gourd in the grafting system. This study indicated that figleaf gourd is not a host of CGMMY.

• Korean Medical Education Review
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• v.13 no.1
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• pp.25-34
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• 2011

Modern medicine has early experienced the absence of mimesis and has been trying to replace the absence with objective grounds and experimental data. However, as medicine became science, the crisis of medicine spread more widely. Microscopic powers and violences are invisible, but individuals are powerless and vainly unable to resist. The anguish or introspection about the situation is sometimes described in stories such as An Engagement by Lee Eung Jun. An Engagement is mentioned in this article due to the writer's attitude, which shows his introspection and desire for harmony through the wounds of each trivial character. The writer is unceasingly talking about suffering people in his story and his seriousness enables readers to find his stronger sympathy over life and death than in any other medical stories. In fact, it is impossible for readers to comprehend the confusing propositions which the writer pours out, and even uncomfortable to read the story. Nevertheless, the propositions are always in contact with reality. Perhaps it is not the writer's confusing propositions that make us uncomfortable. It might be ourselves who are always alienated and starved. We can say that the characters' pains and wounds are phantom pains caused by the absence of mimesis. Since there is no affected area, their pains cannot be measured by only scientific medicine. However, the current medical profession regards objective research evidences as absolute truth and allows them to be the sole criterion. Although scientific skills such as DNA analysis and MRI scan can be the substitutes for doctors' judgment, so much of medicine is still interpersonal relationships. An Engagement. As a person promises to marry another, as all beings together in the world promise to subordinate to one another, every subject is consistently a valuable part of each other for the writer's eyes. He is aware that it is originally impossible to get engaged to the world, but he does not give up the possibility of genuine communication. In today's post-modernism society, where a large number of pathological views define the members and the world itself, endless questioning of existence and digging into pathology will be the only way to reduce the gap between individuals and their world. This article does not say that a literary work will lead the change of medical paradigm. It sprang from a desire for medical humanities to gain more interest of the medical field, where the encounter between literature and medicine is still unfamiliar, and to make medical education recognize the importance of humanities. Starting with this work, I believe that the humanities will help us to find the solution to the age of absence of mimesis and to the crisis of medicine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3260-3268
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• 2009

A test apparatus has been fabricated to simulate chemical effect on head loss through a strainer in a pressurized water reactor (PWR) containment water pool after a loss of coolant accident (LOCA). Tests were conducted under condition of same ratio of strainer surface area to water volume between the test appratus and the containment sump. A series of tests have been performed to investigate the effects of spray, existence of calcium-silicate with tri-sodium phosphate (TSP), and composition of materials. The results showed that head loss across the chemical bed with even a small amount of calcium-silicate insulation instantaneously increased as soon as TSP was added to the test solution. Also, the head loss across the test screen is strongly affected by spray duration and is increased rapidly at the early stage, because of high dissolution and precipitation of aluminum and zinc. After passivation of aluminum and zinc by corrosion, the head loss increase is much slowed down and is mainly induced by materials such as calcium, silicon, and magnesium leached from NUKONTM and concrete. Furthermore, it is newly found that the spay buffer agent, tri-sodium phosphate, to form protective coating on the aluminum surface and reduce aluminum leaching is not effective for a large amount of aluminum and a long spray.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.196-203
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• 1993

Emulsions were prepared with the inversion emulsification method which adopted the agent-in-oil method-dissolving the mixed surfactants composed of the glycerin monostearate, polyoxyethylene(100) monostearate, and polyoxyethylene(20) sorbitan monostearate into mixtures of liquid paraffin and beeswax, and adding the aqueous solution of propylene glycol, gradually-and then their phases and viscosities behaviors in the emulsifying process were investigated. The fine and homogeneous o/w emulsions were formed in the HLB region (HLB 10.1~12.3), showing liquid crystalline phase and white gel phase in the emulsifying process. The phase inversion steps in the emulsifying process appeared as follows, i.e., oil continuous phase${\rightarrow}$liquid crystalline phase${\rightarrow}$white gel phase${\rightarrow}$o/w emulsion. Shear rate-shear stress curves of the prepared emulsions had the yield values which pointed out the existence of inner structure between emulsion particles, and the hysteresis loop which showed that the inner structure wasbroken irreversibly by the shear. The area of hystersis loop, an index of breakdown of inner structure, was increased with the decreasing of the HLB value of emulsifier, Shear time-shear stress curves showed the time dependence of plastic viscosity, and the relaxation time in time thinning behavior(${\lambda}$) indicated that the stability of emulsions prepared with the inversion emulsification method was decreased with the increasing of HLB values of emulsifier and was higher than that of emulsions prepared by homomixer.