• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.198-198
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• 2011

Organocatalysis is a relatively new and popular area within the field of chiral molecule synthesis. It is one of the main branches of enantioselective synthesis with enzymatic and organometallic catalysis. In recent years, immense high quality studies on catalysis by chiral secondary amines were reported. These progresses instantly led to different organocatalytic activation concepts, so thousands of researchers from academia and the chemical industry are currently involved in this field and new ideas, new approaches, and creative thinking have been rapidly emerged. Organocatalysts, some of which are natural products, appear to solve the problems of metal catalysts. Compared to metal-based catalysis, they have many advantages including savings in cost, time, and energy, easier experimental procedure, and reduction of chemical waste. These benefits originate from the following factors. First, organocatalysts are generally stable in oxygen and water in the atmosphere, there is no need for special equipments or experimental techniques to operate under anhydrous or anaerobic conditions. Second, organic reagents are naturally available from biological materials as single enantiomers that they are easy and cheap to prepare which makes them suitable for small-scale to industrial-scale reactions. Third, in terms of safety related catalysis, small organic molecules are non-toxic and environmentally friendly. Therefore, the purpose of this research is to develop novel synthetic methods and design for various organocatalyst. Furthermore, it is expected that these organocatalysts can be applied to a variety of asymmetric reactions and study the transition state of these reactions using a metal sulface. Here, we report the synthesis of unprecedented organocatalysts, proline and pyrrolidine derivatives with quaternary carbon center.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.39-42
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• 2005

This study investigates influence of organic fiber reinforced materials, affecting crack reduction of cement mortar using low grade natural sand(LNS). According to the test, for the properties of fresh mortar, the mortar using natural sand(NS) exhibited that flow value increased until adding most of fiber less than 1$\%$, except for Polyvinly alchol fiber(PVA), and then it decreased. Meanwhile, the mortar mixed with LNS showed that increase of fiber content decrease flow value, regardless of fiber type. Air content increased in the mortar adding nylon fiber(NY) and polypropylene fiber(PP), while it maintained or decreased in the mortar adding cellulose fiber(CL) and PVA. Compressive strength of the mortar does not affect during early age, but mortar using NS and adding 0.1$\%$ of fiber content increased the value, except for PP, at 28 age days, while the mortar mixed with LNS decreased. For the properties of tensile strength, mortar, using NS and adding individually PP and PVA, exhibited higher value. Especially 0.1$\%$ of NY provided the highest value. In addition, the mortar mixed with LNS resulted in improved tensile value as fiber content increased. It is demonstrated that mortar using LNS led to higher length change ratio than natural sand.

• 대한화장품학회지
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• 제31권3호
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• pp.237-244
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• 2005

오랫동안 사용되어진 Sunscreen 제품들은 '화상없이 보기 좋게 태우기'라는 목적으로 발전을 거듭해 왔다. 최근 태양 자외선이 피부암을 유발시키는 주요 원인이며, 화상과 무관한 UVA에 의해서도 피부암이 유발된다는 보고와 함께 '보기좋게 태우기'에서 '태양광선으로부터 보호'라는 목적으로 제품의 진화를 계속해 오고 있다. 최근 이러한 동향과 함께 유럽에서 수년간 유기 UV 차단제가 개발되었으며, 본 보고에서 이들에 대한 발전과정을 논의하고자 한다. 이들 UV 차단제들은 UVB는 물론 UVA를 충분히 잘 흡수할 수 있으며, 어떤한 formulation에도 잘 포함될 수 있는 성질을 가지고 있다. 또한, 이들은 부작용 없는 안전한 물질들이다. 이들 차단제들은 290 nm에서 400 nm의 넓은 범위의 UV를 차단할 수 있어 다른 차단제들과 병용할 필요성을 감소시켜 준다.

• 멤브레인
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• 제22권5호
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• pp.326-331
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• 2012

수중 이 취미를 유발시키는 대표적인 미량오염물질인 2-methylisoborneal (MIB)과 geosmin(지오스민)의 배제율을 소수성 polyethersulfone (PES) 나노분리막(분획분자량 : 400 Da)을 적용하여 다양한 용액조성에서 관찰하였다. 실험결과 적용된 모든 조건에서 지오스민이 2-MIB보다 다소 높은 배제율을 나타내었다. 용액의 pH 효과를 관찰한 결과 pH가 증가할수록 2-MIB와 지오스민 양쪽 모두 배제율이 증가하는 경향을 나타내었다. 한편, 수중 자연유기물질의 존재는 두 미량유기물질의 배제율을 크게 증가시켰으며 이와 같은 현상은 높은 pH일수록 더욱 뚜렷하게 나타났다. 소수성 분리막을 친수성 $TiO_2$ 입자로 표면코팅 시킨 후 배제율을 관찰한 결과 분리막의 표면을 친수화한 후 소수성인 2-MIB와 지오스민의 배제율은 증가하는 경향을 나타내었다. 따라서 소수성 상호작용은 미량유기물질 나노여과 배제율의 중요한 기작 중 하나임을 확인할 수 있었다.

• Geomechanics and Engineering
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• 제5권6호
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• pp.575-594
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• 2013

Organic soils exhibit problematic properties such as high compressibility and low shear strength; these properties may cause differential settlement or failure in structures built on such soils. Organic soil removal or stabilization are the most important methods to overcome geotechnical problems related to peat soils' engineering characteristics. This paper presents soil mechanical intervention for stabilization of peat with sand columns and focuses on a comparison between the mechanical characteristics of undisturbed peat and peat stabilized with 20%, 30% and 40% of sand on the laboratory scale. Cylindrical columns were extruded in different diameters through a nearly undisturbed peat sample in the laboratory and filled with sand. By adding sand columns to peat, higher permeability, higher shear strength and a faster consolidation was achieved. The sample with 70% peat and 30% sand displayed the most reliable compressibility properties. This can be attributed to proper drainage provided by sand columns for peat in this specific percentage. It was observed that the granular texture of sand also increased the friction angle of peat. The addition of 30% sand led to the highest shear strength among all mixtures considered. The peat samples with 40% sand were sampled with two and three sand columns and tested in direct shear and consolidation tests to evaluate the influence of the number and geometry of sand columns. Samples with three sand columns showed higher compressibility and shear strength. Following the results of this laboratory study it appears that the introduction of sand columns could be suitable for geotechnical peat stabilization in the field scale.

• 한국축산시설환경학회지
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• 제5권3호
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• pp.189-196
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• 1999

Anaerobic digestion is a naturally occuring microbial process involving the decomposition of organic materials such as livestock manure. This study explores the effect of the operating conditions, HRT (Hydraulic Retention Time) and feeding frequency on treatment efficiency for digestion of pig slurry, which has been one of most difficult organic waste for proper treatment in livestock production industry in Korea at the present time. The pilot-scale CSTR of 5 m3 in volume was designed. manufactured, and operated at the temperature of 35$\pm$1$^{\circ}C$. The digester was designed to hydraulically stir for complete mixing and to supply heat from the water bath to maintain mesophilic temperature. The HRT of the digester for Test 1 and Test 2, and Test 3 was set for 17 days and 13 days respectively and pig slurry was fed once a day with 300$\ell$ each for Test 1 and Test 3, while twice with 150$\ell$each for Test 2. Test 2 showed better performance by increase of 4% in VS removal efficiency and 5% in biogas production rate. This is mainly attributed to smaller temperature drop by feeding frequently with half amount, which eventually led to lesser impact on anaerobic mocrobes in the digester. Test 2 maintained optimum pH 7.8 which uplifted the activaton of sulfur-reduction bacteria, alkalinity of around 4,000mg/$\ell$, VA of over 3,000mg/$\ell$ for whole period of experiment. Further research may require to provide the practical operation strategy of anaerobic treatment system for treatment of pig slurry.

• 자원리싸이클링
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• 제30권2호
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• pp.53-60
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• 2021

폐리튬이온배터리에 함유된 코발트, 니켈 및 구리를 회수하기 위한 공정 개발의 일환으로 단일금속과 금속혼합물의 침출을 조사했다. 이를 위해 산화제를 첨가하지 않은 무기산과 유기산을 침출제로 사용했다. 본 논문의 실험조건에서 산화제가 없는 무기산과 유기산에서 구리는 전혀 침출되지 않았다. 염산과 황산용액에서 산의 농도, 반응온도, 반응시간 및 광액농도를 변화시켜 단일 금속를 모두 용해시킬 수 있는 조건을 구했다. 또한 염산과 황산용액에서 금속혼합물로부터 니켈과 코발트를 99% 이상 침출시킬 수 있는 조건을 조사했다. 메탄술폰산으로 코발트와 니켈 금속혼합물을 침출시 낮은 반응온도에서 코발트가 선택적으로 침출됐다.

• Journal of Ecology and Environment
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• 제46권3호
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• pp.204-217
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• 2022

Background: Increasing land demands for food production have led to biodiversity loss and land degradation in the Madhupur Sal forest. Reforestation activities such as agroforestry and woodlot plantation support the conservation of diversity, restoration of forest and prevention of soil erosion in degraded natural Sal forest. Knowing about these reforestation activities, this study is needed to compare the species composition, richness, and soil nutrients of these two plantation activities to the natural Sal forest in the degraded Madhupur Sal forest in Bangladesh. Results: The analysis showed that in between the reforestation activities, the highest Shannon-Wiener index (1.79), evenness (0.60) and Simpson's index (0.79) were found in the agroforestry site compared to the woodlot plantation site. On the contrary, the highest species richness (n = 14), tree basal area (19.56 m² ha^-1), Margalef's index (1.96) were recorded in woodlot plantation than in the agroforestry site. We observed that at 0-15 cm depth, soil organic matter (2.39%), total nitrogen (0.14%), available phosphorous (62.67 ㎍ g^-1) and exchangeable potassium (0.36 meq/100 g) in agroforestry plots were significantly higher compared to other forest sites. At topsoil (15-30 cm depth), soil organic matter (1.67%) and available phosphorous (21.09 ㎍ g^-1) were found to be higher in agroforestry site. Conclusions: Both reforestation approaches improved soil function, although woodlot plantation had the higher species richness. Therefore, plantation activities by the sustainable implementation of these two practices are the best alternative to restore the biodiversity, richness and conserve soil fertility in the Madhupur Sal forest of Bangladesh.

• The Plant Pathology Journal
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• 제38권2호
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• pp.115-130
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• 2022

Though information exists regarding the pathogenesis of the shot-hole disease (SH) in flowering cherry (FC), there has been a lack of research focusing on SH management. Therefore, here, we investigated the inhibitory activities of antagonistic bacteria against SH pathogens both in vitro and in vivo as well as their biochemical characteristics and bioactive compounds. Two biosurfactant-producing bacterial antagonists, identified as Bacillus velezensis strains JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal SH pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains also strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, solvent extracts, and biosurfactants of the two strains exhibited antimicrobial activities. Liquid chromatography/electrospray ionization time-of-flight mass spectrometric analysis of the partially purified active fractions revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of FC leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by Epicoccum tobaicum and Bukholderia contaminans, respectively. In addition, the two antagonists produced indole-3-acetic acid, siderophore, and a series of hydrolytic enzymes, along with the formation of a substantial biofilm. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the SH pathogens and their efficiency in the biocontrol of SH.

• 마이크로전자및패키징학회지
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• 제31권3호
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• pp.10-17
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• 2024

본 논문은 전자 기기의 소형화와 유연성을 실현하기 위한 플렉시블 패키징 핵심 기술 중 하나인 Chip On Film(COF) 기술에 대해 논의합니다. COF는 Display Driver IC(DDI)를 유연한 폴리이미드(Polyimide) 기판에 직접 부착하여, 고해상도 디스플레이의 경량화와 두께 감소를 가능하게 합니다. COF 기술은 주로 Organic Light Emitting Diode(OLED) 디스플레이와 같은 고성능 디스플레이 패널에서 사용되며, 스마트폰과 웨어러블 기기와 같은 휴대용 전자 장치에서 핵심적인 역할을 합니다. 본 연구에서는 COF의 주요 구성 요소 및 본딩 기술의 발전을 분석합니다. 특히, 열압착(Thermo-Compression Bonding), 초음파 본딩(Thermo-sonic Bonding)과 같은 최신 본딩 기법의 도입으로, 본딩 신뢰성 및 전기적 성능이 크게 향상되었습니다. 이러한 본딩 기술은 미세 피치 구조에서 높은 전기적 연결성을 유지하면서도, COF 패키지의 기계적 안정성을 강화합니다. 또한, COF 본딩 기술의 향후 발전 방향과 그에 따른 도전 과제를 논의하며, 차세대 디스플레이 및 Advanced 패키징 기술로서의 가능성을 조망합니다.