• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.293-303
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• 2004

This experiment was conducted to investigate the direction or orientation of clay particle movement in argillic horizons (Bt) for clarifying the soil classification of soils. Soil samples were collected from 22 soil series containing Bt horizons. Physical and chemical characteristics and mineral and chemical compositions of clay in the soils were analyzed. Micoromorphological characteristics of the Bt horizons were also investigated with thin sections of the natural undisturbed and oriented soil samples. Average clay content in the Bt horizons was 28% and 1.33 times higher comparing to that in the surface layer. Soil pH was higher, but cation exchange capacity (CEC) and organic matter content were lower in Bt horizon than those in the surface layer. There was an evidence of clay accumulation in Bt horizons of all soil series examined except Bangog series. Although there was an increase of clay content in the horizons in Bangog series, the clay was not originated from illuviation process. The translocation of clay was in the order of an 2:1 expandable clay minerals > 2:1 non-expandable clay minerals > 1:1 clay minerals. The illuvial substances in argillic horizon were composed with clay, amorphous iron and opaque mineral. The micoromorphological features of Bt horizon were void coating, channel infilling and grain coating. There was an apparent boundary between clay coating and the groundmass in residuum and colluvium, but Bt horizon of alluvium was composed of a skew plane amputated by the physical operation.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.89-97
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• 2007

In this study, thermalpretreatment was used to solubilize organic matter contained in sewage sludge before acid fermentation. By thermal pretreatment, solubilization of particulate CODcr, carbohydrate and protein increased. By thermal treatment at $120^{\circ}C$ for 30 minutes, CODcr solubilization efficiency of the primary sludge reached 8.3%. Meanwhile, for the secondary sludge, CODcr solubilization efficiency reached 16.5% because of high solubilization ratio of protein under the same pretreatment conditon. The results of anaerobic biodegradability test showed that both VFAs conversion ratio and hydrolysis rate of organic compounds in sewage sludge were improved by thermal pretreatment. Meanwhile, the optimum thermal pretreatment condition was varied with composition of organic compounds in sludge. In this study, the optimun thermal pretreatment condition of the primary sludge, containing high concentration of carbohydrate, was $80^{\circ}C$ for 30 minutes. Meanwhile, for the secondary sludge, mainly composed of protein, the sludge treated at $120^{\circ}C$ for 30 minutes showed the effective organic removal and VFAs production.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.55-59
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• 1984

An organic compound fertilizer was manufactured using wet oxidation human waste as principal source of phosphorus and organic matter. The waste was treated with sulfuric and glutamic acids to increase the available and water-soluble $P_2O_5$ contents. The treatment of 0.1 N sulfuric acid with 24 hours curing was best way in recovering the maximum percentage of $P_2O_5$ originally in the waste. The particle size distribution of trial product varied considerably in the amount of glutamic acid used for granulation. The number of relatively large fertilizer particles was increased as the amount of glutamic acid was increased. The granule crushing strength was generally high in large granules in which 12.5 weight percent of glutamic acid were used for granulation. The trial product showed high moisture absorption due to its porous structure and chemical makeup.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.442-447
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• 2007

In order to improve the surface hardness of transparent plastic films, organic-inorganic hybrid coating solutions were synthesized by the sol-gel method. The coating solutions were prepared by adding GPTMS (glycidoxypropyl trimethoxysilane) to a colloidal silica (12 nm) suspension. PC(polycarbonate) substrates were dipped into the coating solutions and dried at room temperature for 10 min before being cured at $80^{\circ}C$ for 30 min. The effect of the solution pH and GPTMS content was investigated on the properties of coating films. The pencil hardness and adhesion to substrates of the coating films, prepared at acidic condition (pH 4), showed better properties than those at neutral or basic conditions. Also, the pencil hardness and adhesion to substrates of the coating films increased with increasing GPTMS content.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.57.1-57.1
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• 2009

나노이산화티타늄은 인체에는 화장품, 의약, 식품분야 등에 쓰이고 외부 환경 재료에는 광촉매로서 유독가스 정화제, 옥내 외 항균, 수소발생 가시광 응답형 촉매 및 멤브레인 필터 등과 전자소재용 유전재료, 발광 재료 등 용도가 다양하다. 나노 산화티타늄 화합물의 제조법은 수열합성법, 기상법 등 여러 방법이 있다. 이들에 대한 리뷰의 목적은 2009년도 정부의 투자 계획 중에서 본제목에 관련되는 핵심 산업 재원 원천기술 개발, 태양광, 풍력 등의 신재생 에너지 개발, 록색 기술 개발을 통한 에너지절약형 LED 개발, 차세대 핵심환경 기술 개발, 핵심나노기반기술개발 등의 개발을 위하여 4,363억 원의 예산을 편성하고 연구자와 기술자들이 참여하여 유익한 실적이 창출되기를 원하고 있으므로 본 발표자들은 이 분야에서 연구하는 연구자와 기술자들에게 이 분야에 관련되는 자료를 참고로 제시하는데 있다. 페로브스카이트형 산화물인 유전재료($BaTiO_3$), 발광재료(CaTiO3:Pr3+적색), 박막형 반응기재료($Ca0.8Sr0.2TiO_3$), 등의 여러 가지 산화물은 류통식 급속 승온 수열 합성법, 겔 졸 법, 수열 합성법 등 여러 방법에 의하여 페로브스카이트형 산화물 입자 직경이 약 20nm~100nm 범위까지 합성된다. 태양광을 조사하여 물을분해 해서 수소를 생산하는 산화티타늄계 가시광 응답형 Vis-$TiO_2$ 박막은 기상법으로 제조하는데 한 예로써 RF 스퍼터링법으로 박막을 제조하여 수소와 산소를 회수하였으며, 황도프산화티타늄, 질소 도프 산화티타늄은 유기물 분해에 의한 공해제거, $NO_x$ 제거 등 환경정화에 사용되고, 고온 고압수법/산화티타늄 복합기술에 의해서는 바이오매스 분해 하고, 일종의 수열법인 개량형 HyCOM 법은 가시광 응답성 산화티타늄을 합성하여 NO가스 제거에 사용한다. 이들 여러 방법에 관한 것을 소개하고저 한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.72.1-72.1
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• 2013

광촉매 활용 기술은 수질 및 대기 중의 난분해성 오염 물질 처리 등의 환경 분야에서부터 항균 및 초친수성 기능을 활용한 소재 분야, 그리고 태양광을 이용한 물분해 수소 제조 및 이산화탄소의 전환 등의 인공 광합성 연구 분야까지 그 응용분야가 대단히 넓은 기술이다. 본 강연에서는 이러한 광촉매의 반응 원리와 대표적인 응용분야인 환경 정화 분야 및 에너지 분야에서의 광촉매 기술의 활용, 그리고 현재 광촉매 관련 연구 분야의 주요 관심사 및 미래 성장을 위한 과제 등을 포괄적으로 다루고자 한다. 광촉매 반응은 반도체의 따간격 에너지 흡수에 따라 전자와 정공(+전하를 가진 전자와 같은 거동을 하는 입자)가 발생한 뒤에 일어나는 계면에서의 전자전달 반응을 기초한다. 발생한 정공과 전자는 각각 산화와 환원 반응을 유발하며 이러한 산화, 환원반응을 통해 다양한 분야로의 응용이 가능하다. 환경 정화 분야의 경우, 정공이 물 혹은 공기 속에 존재하는 수분과 반응하여 생성되는 OH 라디칼 ($OH{\cdot}$)의 강력한 산화력을 주로 이용하게 된다. OH 라디칼에 의한 다양한 난분해성 유기물질의 산화분해 반응을 활용하여 고도처리공정이 가능하게 되며, 수계 난분해성 유기오염물질의 제거뿐만 아니라 대기 중에 존재하는 VOCs, 악취물질 등의 분해도 가능하며, 아울러 바이러스나 박테리아와 같은 세균을 제거할 수 있는 것으로 알려져 있다. 한편, 물 분해 수소제조 및 이산화탄소의 전환과 같은 에너지 분야 응용의 경우, 전도대의 전자를 활용한 환원반응에 기초한다. 앞서 언급한 다양한 응용분야에서 활용될 수 있는 광촉매의 종류 또한 매우 다양하며, 이사화티탄(TiO2)는 대표적인 고효율 상용 광촉매이다. 아울러, 원하는 응용 분야에서의 광활성이 높은 새로운 광촉매의 제조 및 평가가 꾸준히 진행되고 있으며, 그 가운데 태양광의 가장 많은 영역을 차지하고 있는 가시광 활성을 갖는 광촉매 개발에 관한 연구가 활발히 수행되고 있다. 이에, 현재까지 개발된 다양한 가시광 광촉매 시스템에 대한 소개 및 각 광촉매 응용분야에서 최근 새롭게 대두되고 있는 이슈들에 대하여 중점적으로 고찰하고자 한다.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.72-81
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• 2022

Numerous studies have investigated the occurrence and fate of microplastics in the environment; however, only limited effort has been devoted to exploring the characteristics of dissolved organic matter (DOM) leached from microplastics. In microplastic (MP)-contaminated environment, MPs are typically mixed with naturally-occurring particles, which interferes with their detection in the environment. Thus, it is necessary to distinguish between the DOM leached from MPs and those leached from natural particles and also to characterize their properties. This study investigated DOM leaching behavior from MPs (polystyrene: PS, polyvinylchloride: PVC) and natural particulates (forest soil: FS, litter leaves: LL) under light, which is considered one of the main weathering processes that affect MPs in the environment. The leached DOM concentrations and fluorescence characteristics were compared under dark versus light conditions. Regardless of the origins, UV light promoted DOM release from all the particulates. More DOM was released from natural particles than from MPs under both conditions. However, the effect of promoting DOM release by UV was more pronounced for MPs than for natural particles. It was observed from fluorescence spectra that the intensity of the humic-like region was substantially reduced when MP-derived DOM was exposed to UV light, whereas the change of intensity was very little for natural particles. Under light conditions, the ratio of protein-like to humic-like fluorescence of MP-derived DOM was higher than that of DOM from natural particles. This study implies that a substantial amount of DOM could be leached from MPs even in MP-polluted environment under UV irradiation. Protein/humic fluorescence ratio could be utilized as a fast probing indicator to separate the two sources of particles under light.

• Korean Journal of Ecology and Environment
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• v.44 no.3
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• pp.292-302
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• 2011

The Lake Sihwa watershed includes industrial, urban, and rural areas simultaneously. In this study, we analyzed the characteristics of dissolved organic matter (DOM) in spatial-temporal runoff patterns at representative sites having different land use in the watershed of Lake Sihwa. The result of synchronous and 3D-EEMs(3-Dimensional Excitation Emission Matrix Spectroscopy) analysis in 4TG (industrial area), fluorescence distribution and variation clearly appeared in the Fulvic-like fluorescence (FLF) and Humic-like fluorescence (HLF) regions along with the Protein-like fluorescence (PLF) region. A characteristic that Peak A (HLF) region fluorescence intensity did not decrease and the HLF region of fluorescence intensity and spatial-temporal changes clearly appeared during rainfall in AS (urban area). The results of fluorescence analysis in MS did not show great changes in PLF and FLF while showing that fluorescence intensity changes over time in the Terrestrial-like fluorescence (THLF) region increased greatly. In conclusion, our results showed significant differences in the runoff characteristics of DOM particularly in industrial, urban and rural area, and these differences should be considered for the efficient controlling of DOM in the watershed.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.15-29
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• 2020

The aims of this study is to improve physical properties of the sewage sludge and the process sludge generated in the leachate treatment by mixing the dry fuel, to develop the neutral solidifing agents that reduce oder, and to recycle the sewage and the process sludges as landfill cover materials. The mixing ratio (W/W) of sludges and dry fuel was appropriate at about 1:1, and the mixed materials were shown to be homogeneous at that ratio. We could know that when the sludges were mixed with dry fuel, moisture contents and viscosities are reduced, and air passages are formed between particles and particles. The various mixing tests and odor tests showed that the neutral solidifing agent was effective for the odor reduction. The main ingredient of the solidifing agent is the ash of sewage sludge, enabling it competitive in waste recycling and production costs. The landfill cover, using developed neutral solidification agent, improved physical properties to satisfy the quality standards and to increase the compressive strength. It also proved to reduce the value of complex oder and the usage of solidification agent to 1/3 (3,000 to 1,000) and to 1/8 (50% to 6%), respectively, from the comparative study with alkaline solidified landfill cover. Further research is under way to prove that this can be mixed with general soil to be used as a soil improvement agent for plant cultivation.

• Applied Biological Chemistry
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• v.24 no.1
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• pp.59-66
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• 1981

Trichoxanthes Kirilowii with high starch-content was investigated to utilize as a food source. The weight and starch content of Trichoxanthes Kirilowii roots increased rapid1y in proporion to the growth period. The seasonal variations of the starch content were $36.5{\sim}48.0%$ (dry basis) from June to December. The chemical properties of natural growth soils of Trichoxanthes Kirilowii contained more organic matter and total nitrogen content than citrus orchard soils, but less mineral; P,K,Ca and Mg. To prepare starch with the plant root, the centrifugal method(3,000 rpm, 20 min) obtained the highest yield. The industrial-scale method, was similar to the processing of sweetpotato starch (tank precipitation method), and was good in quality. The starch granules were mainly spherical with diameters ranging from $5{\sim}16{\mu}$. The density of the starch was 1.535 and amylose content was about 26.7%. The X-ray diffraction pattern showed that the granules were of the B-type. The blue value of starch, amylose and amylopectin was 0.46, 0.80 and 0.18, respectively. The starch contained 0.05% ash, 0.35% crude protein and 34 mg% phosphorus. and had an inital pasting temperature of $63.5^{\circ}C$. The color intensity of the starch which iodine gave rise to absorption maxima at 670nm. The starch paste showed high stability during cold storage at $5^{\circ}C$.