• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1721-1725
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• 2010

This paper reports the fabrication of geometry-controlled carbon microneedles by a backside exposure method and pyrolysis. The SU-8 microneedles are a polymer precursor in a carbonization process, which geometries such as base diameter, spacing, and aspect ratio can be controlled in a photolithography step. Using this fabrication method, highly reproducible carbon microneedles, which have high aspect ratios of more than 10 and very sharp nanotips, can be realized. The quartz surface with carbon microneedles becomes very hydrophilic and its wettability is adjusted by carrying out the silane treatment. In the carbon microneedle array ($3\;{\mu}m{\times}3\;{\mu}m$), the contact angle is extremly enhanced (${\sim}180^{\circ}$); this will be advantageous in developing low-drag microfluidics and labs-on-a-chip as well as in other bio-applications.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.28-36
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• 2005

A hydrometallurgical process to leach cobalt from the waste cathodic active material, $LiCoO_{2}$, and subsequently to separate it by solvent extraction was developed. The optimum leaching conditions for high recovery of colbalt and lithium were obtained: 2.0 M sulfuric acid, 5 $vol.\%$ hydrogen peroxide, $75^{\circ}C$ leaching temperature, 30 minutes leaching time and an initial pulp density of 100 g/L. The respective leaching efficiencies for Co and Li were $93\%$ and $94.5\%$. About $85\%$ Co was extracted from the sulfuric acid leach liquor containing 44.72 g/L Co and 5.43 g/L Li, using 1.5 M Cyanex272 as an extractant at the initial pH 5.0 and in organic to aqueous phase ratio of 1.6:1 under the single stage extraction conditions. The Co in the raraffinate was completely extracted by 0.5 M Na-Cyanex272 at the inital pH 5.0, and an organic to aqueous phase ratio of 1;1. The cobalt sulfate solution of higher than $99.99\%$ purity could be recovered from waste $LiCoO_{2}$, using a series of hydrometallurgical processes: sulfuric acid leaching of waste $LiCoO_{2}$- solvent extraction of Co by Na-Cyanex 271 - scrubbing of Li by sodium carbonate solution - stripping of Co by sulfuric acid solution.

• Journal of Korean Society of Transportation
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• v.31 no.5
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• pp.60-70
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• 2013

This study aims to develop a truck priority on left-turn algorithm that can reduce greenhouse gas emissions by reducing heavy duty truck's stops at signalized intersection. The signal priority is granted for a left-turn phase, because heavy duty trucks can deteriorate left-turn traffic flow due to the low acceleration or deceleration rate and large turn radius. Truck priority allows to provide the stable speed control for heavy duty truck, and reduces emissions at the signal intersection. Also, two signal recovery strategies are compared for various traffic conditions. This study analyzes the effectiveness of truck priority such as greenhouse gas emissions and fuel consumption reduction, and total travel time saving using the PARAMICS and Comprehensive Modal Emissions Model (CMEM). The results show that signal priority for heavy duty trucks has an effect on reducing greenhouse gas emissions and fuel consumptions at non-peak hour. Also, it shows decreasing total travel time due to reducing truck stops.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.778-784
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• 2005

It has been found that the addition of cosurfactant is necessary in order to expand three phase region containing middle phase microemulsion in ternary systems containing alkyl ethoxylate (AEO) nonionic surfactant, commercial lubricant and water. Phase behavior in the surfactant systems with addition of cosurfactant over a temperature range of 30 to $60^{\circ}C$ showed different trends depending on surfactant, temperature and chain length of alcohol added. For the $C_{12}E_4$ system, addition of n-pentanol and n-hexanol both produced a three phase region over a wide range of temperatures but the middle-phase formed was found to be a $L_3$ or D' phase which would not facilitate solubilization of high molecular weight lubricants. On the other hand, for the $C_{12}E_5$ system, the middle-phase microemulsion was found to be formed with addition of a rather long-chain alcohol such as n-hexanol, n-heptanol, n-octanol, or n-nonanol. The results shown with the addition of cosurfactant was understood in connection with interfacial tension measurements and composition analysis. The inability of the hydrocarbon region of the surfactant films to incorporate the large lubricant molecules and high solubility of a hydrophobic surfactant are thought to be the chief reasons for poor solubilization with D' phase.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.320-321
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• 2003

최근 천연물을 중심으로 한 학문이 발전하면서 천연물이 가지는 생리활성 물질에 대한 관심이 중대되고 있다. 또한 인공합성품의 일부가 안정성의 문제가 제기되면서 천연물의 이용분야는 더욱 확대되고 있다. 급속한 경제발전과 생활수준의 향상으로 식생활을 포함한 생활방식의 다양화로 인하여 과거 감염 위주의 질병이 감소하고 선진국형의 만성퇴행성 질환이 증가하는 추세이다. 혈소판은 혈전증(thrombosis)과 지혈증(haemstasis)에서 중요한 역할을 담당하고 있는 인자로서 현관 내 병적 이상으로 인한 과도한 혈전의 생성은 뇌 -심혈관계 질환의 중요한 유발인자로 작용하므로 뇌ㆍ심혈관계 질환이나 항고지혈증을 연구하는데 유용하게 이용되고 있다. 본 연구에서는 토끼 혈액에서 분리한 세정 혈소판 부유액을 이용하여 작약 MeOH 추출물에서 분리한 천연생리활성물질들을 대상으로 혈소판 응집억제활성에 대하여 연구하였다. 작약 MeOH 추출물의 혈소판 응집억제활성 측정에서 강한 혈소판 응집억제활성 작용을 보였다. 따라서 작약 MeOH 추출물을 크로마토그라피법을 이용하여 분리하였고, NMR을 이용한 분광학적 방법으로 지금까지의 분리한 자료와 비교ㆍ분석하였다. Monoterpene glycoside 계열의 성분들인 15개의 compound와 다수의 fraction들을 HPLC를 이용하여 분리하였으며, collagen으로 유도된 혈소판 응집억제활성측정 방법에서 뛰어난 응집억제활성을 보였다. 표준물질을 이용한 HPLC 분석과 ¹H-NMR 관련 자료의 검색을 통하여 최종적으로 compound 1b가 benzoyloxy-paeoniflorin(2.6％). compound 1d가 paeond(1.3％), compound 2c가 albiflorin(3.2％), compound 2e가 paeoniflorin(33.6％)임을 확인할 수 있었다. Compound 3a의 분석결과 benzoyloxypaeoniflorin과 구조적 유사성은 있으나 동일한 구조식으로 확인할 수 없었다. 그러나 collagen에서 응집억제활성이 90％ 이상으로 뛰어난 활성을 나타내므로 benzoyloxypaeoniflorin과 유사한 구조에서 benzoyl group이 다른 작용기로 치환되었거나 R₁ group이 다른 작용기로 치환된 형태로 추측하였다. Benzoyloxypaeoniflorin은 collagen＞thrombin＞U46616＞A.A(arachidonic acid)＞PAF의 순으로 활성을 보였다. 이는 paeoniflorin의 glycoside 5-carbon위치에 위치한 OH기 대신에 benzoyl기로 치환된 benzoyl 기가 혈소판 억제 산물로 작용한 것으로 추측했다. Paeoniflorin.은 U46619＞thrombin＞collagen＞A.A＞PAF순으로 억제를 보였다. Paeoniflorin이 collagen보다 thrombin에서 강한 억제를 보이는 것으로 Ca/sup 2＋/ chelate를 형성함으로 인해 calciu 대사를 저해하는 것으로 추축했다. Compound 3a는 U46619＞collagen＞A.A＞thrombin＞PAF순으로 억제율을 보이므로 이 화합물은 paeoniflorin의 benzoyl기에 OH기가 다른 치환기로 바뀌거나 paeoniflorin의 glycoside 5-carbon 위치의 OH기 대신에 다른 작용기로 치환된 것으로 추정하였다. 이러한 결과로 작약의 주성분인 paeoniflorin과 유사한 구조를 가진 다른 monoterpene glycoside 계열의 화합물들과 비교 분석하고 구조를 화인하고 이들 성분이 어떻게 혈소판 응집억제활성에 작용하는지를 연구하였다.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.542-547
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• 2021

Glass lined impellers are corrosion resistant to most chemicals, including strong acids, and also have a smooth, non-stick surface, easy to clean and free from impurities in the process. Glass lined home base impeller is a multi-purpose impeller designed to stir a wide viscosity range of liquids from low viscosity fluids to high viscosity fluids, among others, cell culture, yeast culture, and beer fermentation pots, especially used for air-water system breathable stirring. The glass lining for HB impellers, which are simple in structure and competitive in performance, is essential to have upper and lower division in order to make the joint area between the impeller and shaft as small as possible. The upper and lower division of the impeller hardly affects the mixing performance, but the aeration performance. In this study, in order to optimize the shape of the Glass Lining HB impeller, a study was conducted on the effect of the angle between the upper and lower impellers, the clearance between the impellers, and the number of baffles on the aeration power. The optimal shape and baffle plate conditions for the Glass lined HB impeller were derived through the study results that the angle and the clearance between the upper and lower impellers decreased the ration of the power consumption with aeration P_g and that without aeration P₀, P_g/P₀.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.99-107
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• 2018

This research has developed a high temperature steam cleaning technology using a ceramic membrane with durability against temperature and pressure conditions. In steam cleaning, steam of $120^{\circ}C$ is injected into the ceramic membrane to induce pyrolysis by the endothermic reaction to remove fouling from the membrane. The water quality of raw water was adjusted to turbidity 10, 25 NTU and DOC 2.5 mg/L, and the membrane was uniformly fouled by constant pressure operation at 100, 200, and 300 kPa. Physical backwashing was performed with water and air at a pressure of 500 kPa and steam at $120^{\circ}C$ was injected for 0 to 5 minutes. As the turbidity concentration and the operating pressure increased, the flux decreased by 0.7 to 14.4%. It is confirmed that 10.7 to 53.8% recovery is possible than physical cleaning at the injection of steam for 3 minutes, so it is considered that the steam cleaning of the ceramic membrane is effective. Compared with CEB after NaOCl (300 mg/L) filtration at 25 NTU and 300 kPa of turbidity, the steam cleaning result for 3 minutes was similar to 46.7% of CEB for 3 hours. It has been confirmed that steam cleaning is suitable for a ceramic membrane having excellent heat resistance against high temperature. It was considered to have better cleaning efficiency as compared with general physical backwashing.

• Journal of Popular Narrative
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• v.27 no.1
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• pp.53-98
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• 2021

This paper examines the ways in which Hollywood feature films produced and widely circulated with the establishment of the studio system was consumed in the ethnically segregated Korean movie theaters in Kyǒngsǒng in the 1920s. Focusing on how those theaters appropriated what Hollywood represented, this paper has three objectives. First, from a historical and economic perspective, I will historicize the emergence of so-called prestige pictures and how movies became a branded product in that process. Second, I will also loot at how Chosǒn Theater, one of the earliest movie theaters in the Korean-resident area in Kyǒngsǒng who sought to be a prestigious movie palace actively exploited Hollywood brand, by foregrounding its Paramount connection, in particular. Lastly, through a close reading of weekly programmes and handbills, I will examine how these promotional print materials, as an intermediating medium, helped to supplement the audiences' viewing of Hollywood movies while creating loyal audiences.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.24-34
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• 2023

The aim of this study was to retrospectively analyze the effects of pulp treatment on exfoliation of primary teeth and its related factors. In this study, 167 teeth of 97 patients aged 6 months to 12 years who were treated with pulp treatment at Dankook Dental Hospital were selected, and information related to pulp treatment and tooth loss was collected. The included subjects were 72 primary anterior teeth (43.1%) and 95 primary posterior teeth (56.9%), of which 56 were males (57.7%) and 41 females (42.3%). The mean follow-up period was 106.1 ± 38.7 months, and the mean age at pulp treatment was 34.8 ± 15.4 months for primary anterior teeth and 69.1 ± 25.1 months for primary posterior teeth. Unilaterally pulpectomized teeth were significantly exfoliated earlier than the same tooth on the opposite side (p < 0.05). Also, in the case of teeth with periapical lesions, despite pulp treatment, the probability of extraction due to infection has been increased on primary anterior teeth (p < 0.05), but not on posterior teeth (p > 0.05). Pulpectomized teeth were lost earlier, an average of 7.8 months for primary anterior teeth and 8.5 months for primary posterior teeth. Early loss of the primary tooth can lead to space loss and premature eruption of the successor, so this can be considered when planning or performing treatment of the primary tooth.

• The Journal of Engineering Geology
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• v.34 no.1
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• pp.1-12
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• 2024

South Korea's mining industry was actively developed until 1980, but subsequent declining profitability forced many mines to close. Most of the abandoned mines are susceptible to persistent subsidence because of the length of time since mining ceased. Accurate prediction of the locations and times of subsidence is difficult; therefore, this study aims to apply continuum analysis to past cases of subsidence to establish a method of predicting the location and magnitude of future subsidence. The study area is an area of ○○ mining located between the Yangsan fault zone and the Moryang fault zone, in which three subsidence events occurred between 2005 and 2009. Drilling surveys and electrical resistivity surveys were performed at subsidence sites determined the distribution of strata, and through laboratory tests obtained the physico-mechanical properties of the rock. Numerical analysis of the results found that the plastic status area includes the areas of actual subsidence and that continuum analysis can also be used to predict the location and magnitude of subsidence caused by mine goaf.