• Membrane Journal
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• v.32 no.6
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• pp.367-382
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• 2022

Numerous metal-organic frameworks (MOFs) produced by periodic combinations of organic ligands and metal ions or metal-oxo clusters have led the way for the creation of energy-efficient membrane-based separations that may serve as viable replacements for traditional thermal counterparts. Although tremendous progress has been made over the past decade in the synthesis of polycrystalline MOF membranes, only a small number of MOFs have been exploited in the relevant research. Intercrystalline defects, or nonselective diffusion routes in polycrystalline membranes, are likely the reason behind the delay. Postsynthetic modifications (PSMs) are newly emerging strategies for providing polycrystalline MOF membrane diversity by leveraging advanced membranes as a platform and improving their separation capabilities via physical and/or chemical treatments; therefore, neither designing and developing MOFs nor tailoring membrane synthesis techniques for focused MOFs is necessary. In this minireview, seven subclasses of PSM techniques that have recently been adapted to polycrystalline MOF membranes are outlined, along with obstacles and future directions.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.620-626
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• 2015

$Ho^{3+}$ doped $SrAl_2O_4$ upconversion phosphor powders were synthesized by spray pyrolysis, and the crystallographic properties and luminescence characteristics were examined by varying activator concentrations and heattreatment temperatures. The effect of organic additives on the crystal structure and luminescent properties was also investigated. $SrAl_2O_4:Ho^{3+}$ powders showed intensive green emission due to the $^5F_4/^5S_2{\rightarrow}^5I_8$ transition of $Ho^{3+}$. The optimal $Ho^{3+}$ concentration in order to achieve the highest luminescence was 0.1%. Over this concentration, emission intensities were largely diminished via a concentration quenching due to dipole-dipole interaction between activator ions. According to the dependence of emission intensity on the pumping power of a laser diode, it was clear that the upconversion of $SrAl_2O_4:Ho^{3+}$ occurred via the ground state absorption-excited state absorption processes involving two near-IR photons. Synthesized powders were monoclinic as a major phase, having some hexagonal phase. The increase of heat-treatment temperatures from $1000^{\circ}C$ to $1350^{\circ}C$ led to crystallinity enhancement of monoclinic phase, reducing hexagonal phase. The hexagonal phase, however, did not disappear even at $1350^{\circ}C$. When both citric acid (CA) and ethylene glycol (EG) were added to the spray solution, the resulting powders had pure monoclinic phase without forming hexagonal phase, and led to largely enhancement of crystallinity. Also, N,N-Dimethylformamide (DMF) addition to the spray solution containing both CA and EG made it possible to effectively reduce the surface area of $SrAl_2O_4:Ho^{3+}$ powders. Consequently, the $SrAl_2O_4:Ho^{3+}$ powders prepared by using the spray solution containing CA/EG/DMF mixture as the organic additives showed about 168% improved luminescence compared to the phosphor prepared without organic additives. It was concluded that both the increased crystallinity of high-purity monoclinic phase and the decrease of surface area were attributed to the large enhancement of upconversion luminescence.

• Elastomers and Composites
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• v.49 no.4
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• pp.330-335
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• 2014

Niobium pentoxide ($Nb_2O_5$) nanoparticles were synthesized using niobium (V) chloride and pluronic F108NF as the precursor and templating agent, respectively. The $Nb_2O_5$-graphene nanocomposites were placed in an electric furnace at $700^{\circ}C$ and calcined under Ar atmosphere for 2 h. The morphology, crystallinity, and photocatalytic degradation activity of the samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and UV-vis spectroscopy. The $Nb_2O_5$-graphene nanocomposites acted as a photocatalyst in the photocatalytic degradation of organic dyes under 254 nm UV light; the organic dyes used were methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and brilliant green (BG). The photocatalytic degradation kinetics for the aforesaid dyes were determined in the presence of the $Nb_2O_5$-graphene nanocomposites.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.277-278
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• 2009

독일 연방작물보호법(PflSchG-Gesetz zum Schutz der Kulturpflanzen, 1986.9. 15 제정)은 식물강화제(한국의 친환경유기농자재와 동일)에 대한 정의를 3가지로 대별하여 명시하고 연방농림생물학청(BBA)에 신고를 의무화하도록 개정(1998.7. 27)하여 법률적인 근거를 마련하였다. 정부조직 개편으로 인하여 2002년 11월 1일부터 연방소비자보호 및 식품안전청(BVL)에서 유기농자재 등록 허가 업무를 주관하고 있다. 식물강화제는 작물보호법에 의하여 허가되는 농약, 생장촉진제, 작물보조제 및 비료관리법(Dungemittelgesetz)에 의한 식물영양제, 식물보조제, 작물재배 배양토 및 토양개량제 등과는 차별화하여 명시하고 있다. 식물강화제는 독일 작물보호법(PflSchG-Gesetz zum Schutz der Kulturpflanzen; Plant Protection Act) 제1장 제2조 10항에 의거하여 (1)유해생물에 대한 저항력을 높여주는 물질, (2)비기생성 피해에 대하여 식물을 보호해 주는 물질, (3)재배작물 이외의 잘려진 관상식물에 사용되는 물질로 정의하고 있다. 이러한 법률적 정의의 요지는 인간과 동물의 건강 및 자연계에 해로운 영향이 없으면서 식물체에 유해한 생물에 대하여 저항성만을 높여주는 물질을 말하며, 기상 및 환경공해 등에 의한 장해도 유해생물에 의한 것과 동일하게 간주되며 이에 대한 저항성을 높여 주는 물질도 포함시키고 있다. 식물강화제는 원칙적으로 유해생물 방제에 직접적으로 작용시키기 위한 이용목적으로 사용할 수 없으며, 단지 작물의 저항성을 높이는 경우에 한하여야 사용된다. 식물강화제의 등록 허가신청은 생산자, 판매업자 또는 수입업자가 연방소비자보호 및 식품안전청(BVL)에 신청하여야 한다. 이렇게 신청된 식물강화제는 작물보호법 제2조에 의거하여 이루어진다. 연방소비자보호 및 식품안전청의 작물보호제의 관리부서는 특별한 문제가 없는 한 4개월 이내에 등록을 허가하고 목록을 홈페이지에 목록을 공시한다. 목록공시는 통상적으로 매월 초순에 1회 게시된다. 허가 등록 절차는 맨처음 서류가 접수되면 구비서류가 완전한지 여부를 검토하여 신청서류에 문제가 없으면 4부를 복사하여 연방소비자보호 및 식품안전청(BVL, Federal Office of Consumer Protection and Food Safety), 환경청(UBA, Federal Environment Agency), 연방농림생물학청(BBA, Federal Biogical Research Centre for Agriculture and Forestry) 및 위해성평가연구소(BfR, Fedral Institute for Risk Assessment)에 우편으로 해당부서에 발송한다. 4개 기관이 검토한 내용이 서로 상이한 판단을 하였을 경우 연방소비자보호 및 식품안전청은 등록 허가결정을 하기 전에 "전문가위원회"를 개최하여 의견을 청취한다. 전문위원회는 연방농림생물청, 환경부, 위해성평가연구소 연구원 등 작물, 독성 및 환경보호 전문가 25인으로 구성되어있다. 연방소비자보호 및 식품안전청의 작물보호 제2부서(식물강화제 검토부서)는 전문위원과 검토기관의 의견을 종합하여 자체적으로 등록 허가 여부를 결정하여 제품 신청자에게 결정 내용을 통보함으로서 등록절차가 마무리 된다. 독일의 식물강화제, 즉 유기농자재는 국가에서 허가한 제품에 한하여 유기농업연구소(FiBL)에서 허용목록 책자를 만들어 유기농업단체 제공하면 단체에 따라 사용가능 유기농자재 제품을 다시 선별하여 회원에게 알려준다. 2009년 11월 30일 현재 독일의 연방소비자보호 및 식품안전청(BVL)에서 허가 공시한 식물강화제는 490개 제품에 이르고 있다.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.593-599
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• 2023

Nickel oxide (NiO) nanoparticles were successfully synthesized by a simple liquid phase process for producing ceramics powder using a precursor impregnated with a nickel(II) nitrate hexahydrate aqueous solution in an industrial pulp. The microfibrile structure of the precursor impregnated with nickel nitrate hexahydrate aqueous solution was confirmed by scanning electron microscope (SEM), and the crystal structure and particle size of nickel oxide (NiO) particles produced as the heat treatment temperature of the precursor were analyzed by X-ray diffraction (XRD) and SEM. As a result, it was confirmed through XRD and SEM analysis that the temperature at which the organic material of the precursor is completely thermally decomposed was 495-500℃, and the size and crystallinity of the nickel oxide particles produced increased as the heat treatment temperature increased. The size of the nickel oxide particles obtained by heat treatment at 500-800℃ for 1 hour was 50-200 nm. It was confirmed by XRD and SEM analysis that a NiO crystal phase was formed at a heat treatment temperature of 380℃, only a single NiO phase existed until 800℃.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.395-412
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• 2023

The morphology and whole genome sequence of Hyphantria cunea nucleopolyhedrovirus W1 (HycuNPV-W1) isolated in Korea were analyzed for the use as an eco-friendly control agent against H. cunea. The HycuNPV-W1 had irregular tetrahedral polyhedra with a size of 1.5-2.2 ㎛ which is similar to that of previously reported HycuNPV isolated in Korea. As a result of whole viral genome analysis, HycuNPV-W1 was composed of 131,353 bp, which is 1,606 bp shorter than that of the previously reported HycuNPV. The G+C content was 45% and six of the homologous repeated regions were found, so there was no significant difference from the previous report. As a result of ORF analysis, HycuNPV-W1 contains total of 145 ORFs which is three ORFs less than the previous report, while two ORFs were exclusively found in HycuNPV-W1. The functions of these ORFs remains unclear and are not considered to have a significant influence on the characteristics of the HycuNPV. The genome vista analysis showed that the overall sequence identity between HycuNPV-W1 and the previously reported HycuNPV was very high. The whole genome of HycuNPV-W1 analyzed was found to be similar to those of the previously reported HycuNPV, however, it is supposed to be a novel resource in Korea with different isolate.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.855-859
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• 2023

Copper oxide (CuO) nanoparticles were successfully synthesized using a precursor in which industrial starch was impregnated with an aqueous solution of copper (II) nitrate trihydrate. The microstructure of the precursor impregnated with an aqueous solution of copper nitrate trihydrate was confirmed with a scanning electron microscope (SEM), and the particle size and the crystal structure of the copper oxide particles produced as the temperature of the heat treatment of the precursor increased was analyzed by X-ray diffraction (XRD) and the scanning electron microscope (SEM). As a result of the analysis, it was confirmed that the temperature at which the organic matter of the precursor is completely thermally decomposed is 450-490℃, and that the size and crystallinity of the copper oxide particles increased as the heat treatment temperature increased. The size of the copper oxide particles obtained through heat treatment at 500-800℃ during 1 hour was 100nm~2㎛. It was confirmed that the copper oxide crystalline phase is formed at a heat treatment temperature of 400℃, and only the copper oxide single phase existed up to 800℃. And it was also confirmed that the size of particles produced increased as the calcination temperature increased.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.179-183
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• 2013

Marine-derived microbes have yielded a variety of metabolites so far. In the course of the project to find metabolites from marine microbes, an isolate of Aspergillus protuberus (SF 5767) was selected for chemical investigation. A large scale culture of this strain in PDA media was extracted with an organic solvent and the extract was fractionated by silica gel column chromatography. Repeated reverse phase HPLC of the fractions led to the isolation of three metabolites. Their chemical structures were elucidated as deoxybrevianamide E (1), brevianamide V (2), and ergosterol peroxide (3) on the basis of spectroscopic data including MS, NMR, and UV. To the best of our knowledge, chemical investigation of A. protuberus was conducted for the first time in this study.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.506-511
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• 2008

In this study sol-gel and combustion process was surveyed for the preparation of the red $Y_2O_3$: Eu phosphor, and the properties of phosphor was considered. Chelation and hydrolysis in amorphous citrate sol-gel process were completed in initial reaction stage, and water-forming condensation was superior to organic acid-forming condensation. The mole ratio of citric acid to metal ion had to be above to for the progress of sol-gel process. The dried gel powders are mostly amorphous, and crystallize completely at $700^{\circ}C$, and the crystallinity increases with increasing calcining temperature. The luminescence property of the phosphor was analyzed by measuring the emission spectra. The luminescence intensity increases when the calcination temperature and concentration of metal ions in solution increase.

• Clean Technology
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• v.29 no.1
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• pp.71-75
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• 2023

In general, the presence of non-selective intercrystalline (grain boundary) defects in polycrystalline metal-organic framework (MOF) or zeolite membranes, which are known to be ca. 1 nm in size, causes lower membrane performance (selectivity) than the intrinsically expected. In this study we show that applying a thin polymeric coating of polydimethylsiloxane (PDMS) on a polycrystalline MOF membrane is effective to cap the non-selective intercrystalline defects and therefore improve membrane performance. To demonstrate the concept, first, polycrystalline UiO-66, one of Zr-based MOFs, membranes were prepared by an in-situ solvothermal growth. By controlling membrane growth condition with respect to growth temperature, we were able to obtain polycrystalline UiO-66 membranes at 150 ℃ with intercrystalline defects of which the quantity is not significant, so it can be plugged by the suggested PDMS deposition. Second, their performances were compared before and after the PDMS deposition. As expected, the PDMS deposition ended up with a noticeable increase in CO₂/N₂ ideal selectivity from 6 to 14, indicating successful intercrystalline defect plugging. However, the enhancement in CO₂/N₂ selectivity was accompanied by a significant reduction in CO₂ permeance from 5700 to 33 GPU because the PDMS deposition not only plugs defects but also forms a continuous coating on membrane surface, adding an additional transport resistance.