• Resources Recycling
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• v.15 no.2 s.70
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• pp.50-57
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• 2006

Production of activated carbon from woody fish parking cases has been studied using waste sulfuric acid as an activating agent for the purpose or promoted recycling of woody fishing port wastes. The adsorption capacity of produced activated carbon was observed to increase with activation temperature and reached its maximum at ca. $650^{\circ}C$ under the experimental conditions. However, the adsorption capacity of activated carbon became deteriorated above this temperature due to the thermal degeneration of its structure. Optimal activation time was found to be about 120 minutes and 1:3 weight ratio of raw material and activating agent was appropriate for increased adsorption capacity of activated carbon under the conditions of $550^{\circ}C$ and 60 minutes of activation time. Regarding the effect of the concentration of activating agent on activation, ca. 1.2 M of sulfuric acid was observed to be proper for an optimal activation or raw material. Comparison of the activation power of sulfuric acid with nitric acid showed that sulfuric acid was superior to nitric acid, however, with regard to the yield of activated carbon there was no significant difference between the two activating agents. The degree of dispersion of carbon particles was shown to be relatively high in neutral condition and the produced activated carbon was considered to be effectively employed for the treatment of metal ions in wastewater due to its negative surface charge in aqueous condition.

• 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.

• Journal of Science Education
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• v.46 no.3
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• pp.255-265
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• 2022

The purpose of this study is to analyze and compare brain activation that appears in the self-regulation process of biology major and non-major college students in life science learning. The self-regulation task implemented a life science learning situation with the concept of biological classification. The brain activation of college students was measured and analyzed by fNIRS. In the assimilation process, bilateral FP and left DLPFC show significant activation, and the two groups show a difference in the left OFC activation related to motivation and reward. In the conflict process, the left DLPFC shows significantly lower activation in common, and the two groups show a difference in activation between BA 46, which is related to recent memory, and BA 47, which is related to long-term memory. In the accommodation process, a significantly high activation was found in right DLPFC in common, and the two groups show a difference in activation between right DLPFC and right FP. These areas are in the right frontal lobe area and are related to the understanding of life science knowledge. As a result of this study, it can be seen that the brain activation patterns of biology major and non-major college students are different in the self-regulation process. In addition, we will propose additional neurological studies on self-regulation and present systems and learning strategies that can be constructed in school settings.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.251-254
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• 2012

In this paper, the output characteristics of GaN-based LED considering quantum well structure are analyzed. The basic structure of the LED consists of active region of GaN barrier and InGaN quantum well between AlGaN EBL(Electron Blocking Layer) and AlGaN HBL(Hole Blocking Layer) on GaN buffer layer. The output power, internal quantum efficiency characteristics of LED active region considering thickness of quantum well, number of quantum well and doping of barrier are analyzed using ISE-TCAD.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.459-467
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• 1989

When the sufactants are dissolved in water, they associate to form micelles and solubilize oil inside the micelle to form swollen micelles. Although spherical aggregates like micelles and swollen micelles occupy the same regions in the phase diagram of water-oil-surfactant systems, they are treated in different viewpoint for the formation of such aggregates. Hence a unified thermodynamic formalism for the formation of such structure is presented in this study. In all cases, the to ideal solution theory is applied for dilute system and the energy of formation is expressed as the sum of hydrophobic interaction energy and surface energy due to surfactant film. From the model, critical micelle concentration (CMC), average aggregation number, and solubilization ratio are predicted and compared with the known experimental observation.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.207-209
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• 2005

현재 고정원에서 상용화 촉매로서 사용되는 V$_{2}$O$_{5}$/TiO$_{2}$계 촉매는 고온 영역에서 최적 활성반응을 보이나 NH$_{3}$의 산화반응으로 인해 NO$_{X}$의 제거효율을 낮추는 원인과 가열설비의 추가적인 설치에 따른 초기 투자비, 운전비용 상승 및 촉매 수명 단축 등의 경제적, 기술적인 문제점을 나타내고 있다. 본 연구에서는 저온 영역에서 높은 활성반응을 나타내는 촉매기술의 SCR적용시 배출가스 온도의 100$^{\circ}C$ 감소에 따른 동력비의 절감과 촉매 수명 연장, 경제적, 기술적인 문제점을 해결할 수 있을 것으로 사료된다.

• Annual Conference on Human and Language Technology
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• 2004.10d
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• pp.270-272
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• 2004

본 논문에서는 뇌손상으로 인하여 난독증을 보이는 환자를 대상으로 시각적 단어 재인과정에 대한 평가와 기능적 자기공명영상기법을 통한 언어처리과정의 대뇌활성 양상을 살펴봄으로써 난독증의 특성을 알아보고자 한다. 인지신경심리학적 언어행동평가를 통해 환자 JYM는 자소-음소 변환(grapheme-phoneme conversion)경로와 직접 경로(direct route) 모두가 손상된 심층성 난독증(deep dyslexia)으로 보이며. 기능적 자기공명영상촬영 결과 언어처리과정에서 특정한 언어관련영역보다 등외측전전두영역과 시각피질의 활성이 증가되는 양상을 나타냈다.

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.560-564
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• 2009

ZnO and Mn-substituted $Zn_{0.95}Mn_{0.05}O$ were synthesized by using precipitation method. $Zn_{0.95}Mn_{0.05}O$ compound absorbed UV light as well as hole range of visible light ($400{\sim}800$ nm). Results obtained revealed that $Zn_{0.95}Mn_{0.05}O$ showed higher activity than P-25 for visible-photocatalytic degradation of 1,4- dichlorobenzene.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.11a
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• pp.143-144
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• 2018

360 비디오는 VR 응용의 확산과 함께 몰입형 미디어로 주목 받고 있으며, JVET(Joint Video Experts Team)에서 post-HEVC 로 진행중인 VVC(Versatile Video Coding)에 360 비디오 부호화도 함께 고려하고 있다. 360 비디오 부호화를 위하여 변환된 2D 영상은 투영 면(face) 간의 불연속성과 비활성 영역이 존재할 수 있으며 이는 부호화 효율을 저하시키는 원인이 된다. 본 논문에서는 SSP(Segmented Projection)에서의 이러한 불연속성과 비활성 영역을 줄이는 효율적인 기하학적 패딩(padding) 기법을 제시한다. 실험결과 제안 기법은 복사에 의한 패딩을 사용하는 기존 SSP 대비 주관적 화질이 향상된 것을 확인 할 수 있었다.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.101-106
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• 1998

Two types of CoMo/zeolite as well as $NiMo/{\gamma}-Al_2O_3$ were prepared and their activities and selectivities of low-temperature dibenzothiophene(DBT) hydrodesulfurization(HDS) were studied in high pressure fixed bed reactor. The HDS activities of CoMo/zeolites were higher than that of $NiMo/{\gamma}-Al_2O_3$ at temperatures below $225^{\circ}C$ while they were lower than that of $NiMo/{\gamma}-Al_2O_3$ at temperatures higher than $275^{\circ}C$. The main products from $NiMo/{\gamma}-Al_2O_3$ were biphenyl and cyclohexylbenzene. The product distribution of CoMo/zeolite catalysts was different from that of $NiMo/{\gamma}-Al_2O_3$. It is speculated that DBT is converted to alkylcyclohexane over zeolite based catalysts through both alkylation and hydrogenation reactions. The crystal structure of molybdenum was $MoO_3$ in fresh zeolite support while mixtures of $MoO_3$ and $MoS_2$ were observed in the aged catalyst.