• Transactions of the Korean hydrogen and new energy society
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• v.33 no.3
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• pp.209-218
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• 2022

Recently, research on the development of anion exchange membranes (AEMs) has received considerable attention from the scientific community around the world. Here, we fabricated a series of AEMs with branched structures with different alkyl spacers and conducted comparative evaluations. The introduction of these branched structures is an attempt to overcome the low ionic conductivity and stability problems that AEMs are currently facing. To this end, branched polymers with different spacer lengths were synthesized and properties of each membrane prepared according to the branched structure were compared. The chemical structure of the polymer was investigated by proton nuclear magnetic resonance, Fourier transform infrared, and gel permeation chromatography, and the thermal properties were investigated using thermogravimetric analysis. The branched anion exchange membrane with (CH₂)₃ and (CH₂)₆ spacers exhibited ionic conductivities of 8.9 mS cm^-1 and 22 mS cm^-1 at 90℃, respectively. This means that the length of the spacer affects the ionic conductivity. Therefore, this study showing the effect of the spacer length on the ionic conductivity of the membrane in the polymer structure constituting the ion exchange membrane is judged to be very useful for future application studies of AEM fuel cells.

• Journal of Adhesion and Interface
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• v.11 no.4
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• pp.155-161
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• 2010

A series of ethylene vinyl acetate (EVA) based hot melt adhesives containing different types and compositions of tackifier resins were prepared to investigate their rheological behavior and T-peel adhesion strength on polyurethane (PU) elastomeric sheets. C5 aliphatic hydrocarbon resin (C5 resin), C9 aromatic hydrocarbon resin (C9 resin), hydrogenated dicyclopentadiene resin ($H_2$-DCPD resin), and dicyclopentadiene and acrylic monomer copolymer resin (DCPD-acrylic resin) were used as the tackifiers for the hot melt adhesives. To determine the polarity of the tackifiers, their oxygen contents were analyzed, and the DCPDacrylic resin was found to contain an oxygen content higher than the other tackifiers. Only the DCPD-acrylic resin showed complete miscibility with EVA and the homogeneous phase of the hot melt adhesive blends at all compositions. The T-peel adhesion strength between the hot melt adhesives and polyurethane elastomeric sheets was mainly affected by the polarity of the tackifier resins in the hot melt adhesives, rather than by the storage moduli, G', of the hot melt adhesives themselves.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.325-326
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• 2006

현 화학플랜트에서 사용되고 있는 ABS 수지 응집 공정의 경우 교반기 내부의 불균일한 유동분포와 유동메커니즘의 문제점은 공정 제품의 생산성을 저하 시키는 원인으로 작용하고 있다. 그러나 우수한 성능의 산업용 교반기를 설계하기 위해선 반드시 교반성능에 영향을 미치는 다양한 내부의 유동특성의 정량적인 실험 데이터 확보가 필요하나, 3차원적 비정상 특성을 나타내는 복잡한 구조의 내부 유동특성에 관한 정량적 해석은 현재까지도 상당한 어려운 문제로 남아있다. 이에 이런 문제점을 개선하여 생산성을 향상시키기 위해서는 PIV 기법을 이용한 교반기 내부의 유동분포와 유동메커니즘을 규명하여 교반기 내부의 최적화된 유동을 형성시키는 임펠러의 형상을 개발하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.325-327
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• 2003

원자력 발전소 2차계통수에는 pH를 조절하여 부식을 억제하기 위해 pH제어제로 암모니아를 사용하였으나 상변화 지역에서 액상의 pH가 낮아 부식생성물이 생성, 증기발생기로 유입되어 진열관의 부식을 촉진 시킨다. pH 제어제로 암모니아 대신 ETA를 도입하여 pH를 증가시키고 증기발생기로 유입되는 부식생성물의 양을 감소하여 진열관의 부식을 억제시키고 있다. 그러나 암모니아에서 ETA로 변경함에 따라 증기 발생기취출수계통의 탈염의 운진기간이 단축되었다. 따라서 본 연구의 목적은 탈염기의 수지 교체주기도 연장시키고 안전성도 확보할 수 있는 탈염기내 양ㆍ음이온 이온교환수지 조성 비율을 최적화하는데 있다. 연속화학평형모델을 이용한 결과 양ㆍ음이온 이온교환수지 비율이 10:1일 경우 최적인 것으로 조사되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.174-174
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• 2017

습지는 생산성이 높은 생태계이며 범람원, 수문저장, 오염원의 분해 및 침전의 기능과 동시에 동식물의 서식처를 제공하는 인간의 복지에 매우 유용한 자연공간이다. 습지의 생태적, 수문학적 기능을 유지하기 위해서는 습지 내 유량의 확보가 필수적이다. 따라서, 습지를 유지하고 관리하기 위해서는 유량 변동을 분석하여 유량 변동에 따른 습지 관리를 할 필요가 있다. 우리나라의 산지습지는 주변과 고립되어 있어 외부의 위협에 민감하고, 특이하며 다양한 생물상이 다양하게 분포되어 있어 생태학적 가치가 매우 크다. 특히 양산지역 산지에는 고산습지가 많아 멸종위기종, 천연기념물, 희귀동물이 살고 있는 청정지역이다. 본 연구에서는 다양한 야생생물이 분포하는 보전가치가 높은 산지습지인 경남 양산 장군습지를 대상으로 습지 내 유량 변동에 따른 습지 유지관리방안을 제안하고자 한다. 이를 위해, 습지유역으로 유입되는 물의 양과 유출되는 물의 양의 차이를 분석하는 물수지 방법을 적용하여 습지 내의 유량 변동을 분석하였다.

• Journal of Life Science
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• v.19 no.12
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• pp.1690-1697
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• 2009

CD11c and costimulatory molecules such as CD80 and CD86 express mainly in dendritic cells (DCs). In this study, we investigated the biologic effects of recombinant Fms-like tyrosine kinase-3 (Flt-3) ligand on the expression of DC surface markers, including CD11c in leukemia cell lines, such as KG-1, HL-60, NB4, and THP-1 cells. The expression of the Flt-3 receptor was found in NB4 and HL-60 cells, as well as KG-1 cells, but not in THP-1 cells. When KG-1 cells were cultured in a medium containing Flt-3 ligand or granulocyte macrophage-colony stimulating factor (GM-CSF) plus tumor necrosis factor (TNF)-$\alpha$, cell proliferation was inhibited and the expression levels of CD11c, major histocompatibility complex (MHC)-I, and MHC-II were increased in the cells. Flt-3 ligand also increased the expression level of CD11c on HL-60 and NB4 cells, but not on THP-1 cells. In comparison with CD11c expression, the expression level of CD11b on KG-1 cells, but not on NB4 and HL-60 cells, was slightly increased by Flt-3 ligand. Flt-3 ligand induced phosphorylation of extracellular signal-regulated kinase-1/2 (ERK-1/2) and p38-mitogen-activated protein kinase (p38-MAPK) in KG-1 cells, and the up-regulation of CD11c expression by Flt-3 ligand in the cells was abrogated by PD98059, an inhibitor of MEK. The results suggest that Flt-3 ligand up-regulates DC surface markers on $CD34^+$ myelomonocytic KG-1 cells, as well as promyelocytic leukemia cells, and that the differentiation of the leukemia cells into DC-like cells by Flt-3 ligand is mediated by ERK-1/2 activity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.25-32
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• 2009

The glass-ceramics composed of coal bottom ash produced from a thermal power plant, $Na_{2}O$ and $Li_{2}O$ as a flux agent and $TiO_2$ as a nucleation agent were fabricated and its microstructures were analyzed. The nepheline was a major crystal phase in the glass-ceramics fabricated and its amount increased with $TiO_2$ addition. The glass-ceramics without $TiO_2$ addition had the thick surface crystals induced by a surface-crystallization mechanism and no crystal in the interior matrix. The surface crystallization, however, was restrained and the interior matrix was completely crystallized showing dendrite shape spread with fine particles < $1{\mu}m$ when added with $TiO_2$ above 4 wt%. For the glass-ceramics containing 6 wt% $TiO_2$, the $5{\mu}m$-long dendrite crystal; were interlocked each other which could suppress the crack propagation effectively at the external loading applied.

• The Korean Journal of Mycology
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• v.40 no.1
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• pp.1-6
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• 2012

In this study, soil samples were collected from cultivated fields of 1-5 year old Korean ginseng in Geumsan, Korea. Spores of arbuscular mycorrhizal fungi were extracted from soils and identified using morphological characteristics and 18s rDNA sequences of the spores. Total 10 species of AMF were identified: Acaulospora longula, Archaeospora trappei, Glomus caledonium, Glomus etunicatum, Glomus intraradices, Glomus mosseae, Glomus sp., Paraglomus occultum, Paraglomus brasilianum, and Scutellospora heterogama. Relative abundance of spores of A. trappei were increased with increase of cultivation period of the ginseng. However, relative abundance of other species of AMF and Shannon diversity (H') of AMF were significantly decreased with the increase of cultivation periods of the ginseng.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.276-281
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• 2008

Because the distribution systems experience frequently the fault by several causes, the identification task of fault location plays very important role in the view point of power supply reliability. The distribution systems are designed as radial structure with three-phase and single-phase branch line to supply the electric power to the widely dispersed loads, and it have a several load taps within each line segment. it makes the accurate fault distance determination difficult. Accordingly in this papers, the existing fault point determination methods are surveyed and analyzed, and then a fault distance determination method for distribution feeder is adopted which can be executed effectively in DAS center. Finally, the adopted method is verified using EMTP simulation.

• Journal of Adhesion and Interface
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• v.11 no.1
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• pp.9-14
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• 2010

O/W emulsions were prepared with the phase inversion emulsification methods. The emulsifiers were used the UNIQ-1 (isopropylamine alkyl aryl sulphonate) and UNIQ-2 (alkoxylated glycol ether). Investigated effect that HLB value, agitator velocity and manufacture temperature get in mean particle size of emulsions. Mean particle size receives much effect of HLB value. Also, estimated stability about storage temperature and light. Emulsion's mean particle size was 193 nm lastly, reduced VOC amount used 90% than existing alkyd resin.