• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.43-48
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• 1993

A laboratory study was cunducted to obtain fundamental informations on environmental-conservative treatment technique of soiled animalwaste. The release rate of inorganic nitrogen which mineralized from solid pigwaste and the effect of nitrification inhibitor(Dicyandiamide, DCD) on nitrate concentration of fresh or fermented pigwaste were weekly checked for ten weeks under incubation condition. Average pH of soild pigwaste was maintained over 8 unit during all incubation periods with no difference by nitrification inhibitor addition and the pHs of fresh- or fermented pigwaste without DCD were elevated by passing time 0.04, 0.058 pH unit/week (P<0.05) during incubation. While $NH_4-N$ concentration of fermented pigwaste until two week was nearly the same as it before incubation, $NH_4-N$ concentration of fresh pigwaste was remarkably increased upto 3,732 ppm for 1 week after incubation and the portion of increased $NH_4-N$ concentration, 2,473 ppm was 20.1% of indigenous organic nitrogen of fresh pigwaste. By the passing incubation time, $NH_4-N$ concentration began to lower linearly at not only fresh- but fermented pigwaste after 1 or 2 week, respectively and the $NH_4-N$ concentration loss rate at fresh pigwaste was 61.8 ppm/week with DCD addition and 72.3ppm/week with no DCD. There was positive relationship between $NO_3-N$ concentrations of fresh pigwaste by the addition of DCD or not and $NO_3-N$ concentraion was significantly lowered with DCD treatment($r=0.79^{**}$).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.4
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• pp.207-217
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• 2011

In this study the complex formation reactions between uranium(VI) and 2,6-dihydroxybenzoate (DHB) as a model ligand of humic acid were investigated by using UV-Vis spectrophotometry and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The analysis of the spectrophotometric data, i.e., absorbance changes at the characteristic charge-transfer bands of the U(VI)-DHB complex, indicates that both 1:1 and 1:2 (U(VI):DHB) complexes occur as a result of dual equilibria and their distribution varies in a pH-dependent manner. The stepwise stability constants determined (log $K_1$ and log $K_2$) are $12.4{\pm}0.1$ and $11.4{\pm}0.1$. Further, the TRLFS study shows that DHB plays a role as a fluorescence quencher of U(VI) species. The presence of both a dynamic and static quenching process was identified for all U(VI) species examined, i.e., ${UO_2}^{2+}$, $(UO_2)_2{(OH)_2}^{2+}$, and $(UO_2)_3{(OH)_5}^+$. The fluorescence intensity and lifetimes of each species were measured from the time-resolved spectra at various ligand concentrations, and then analyzed based on Stern-Volmer equations. The static quenching constants (log $K_s$) obtained are $4.2{\pm}0.1$, $4.3{\pm}0.1$, and $4.34{\pm}0.08$ for ${UO_2}^{2+}$, $(UO_2)_2{(OH)_2}^{2+}$, and $(UO_2)_3{(OH)_5}^+$, respectively. The results of Stern-Volmer analysis suggest that both mono- and bi-dentate U(VI)-DHB complexes serve as groundstate complexes inducing static quenching.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.51-57
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• 2000

Waste newspapers was used as an amendment to adjust the moisture of household food wastes for composting. The mixture of household food wastes and waste newspapers was composted in an especially designed small home composter, where the early fed composting materials were discharged early. The temperature inside composting materials was influenced very much by that of outside, because the composter was not insulated. Accordingly, the higher the outside temperature was, the higher the decomposition rate was. The temperature inside composting materials did not reach to optimum, because the amount of composting materials added in the composter everyday was too little, and it caused too high water content of discharged compost after 15 weeks. Therefore, it was required that the composter must be insulated to maintain the higher temperature. The inorganic compounds$(K_2O,\;CaO,\;MgO,\;P_2O_5)$ and heavy metals(Zn, Cu, Cr, Cd, Hg, As) were accumulated obviously in produced compost, when dry recycled compost was reused as the amendment for adjusting the moisture.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.339-346
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• 2019

Based on the $8^{th}$ Basic Plan for Electric Power Demand and Supply, an estimation has been made for inventories and characteristics of spent fuel (SF) to be generated from existing and planned nuclear power plants. The characteristics under consideration in this study are dimensions, fuel array, $^{235}U$ enrichment, discharge burnup, and cooling time for each fuel assembly. These are essentially needed for designing a disposal facility for SFs. It appears that the anticipated quantity by the end of 2082 is about 62,500 assemblies for PWR SFs. The inventories of Westinghouse-type and Korean-type SFs were revealed to be 60% and 40%, respectively as of the end of 2018. The proportion of SFs with initial $^{235}U$ enrichment below 4.5 weight percent (wt%) was shown to be approximately 90% in total as of the end of 2018. As of 2077, more than 97% of SFs generated from Westinghouse-type nuclear reactors were shown to have cooling time of over 50 years. As of 2125, more than 98% of SFs generated from Korean-type nuclear reactors were shown to have cooling time of over 45 years. Based on these results, for the efficient design of a disposal system, it is reasonable to adopt two types of reference spent fuel. SF of KSFA with $^{235}U$ enrichment of 4.5 wt%, discharge burnup of 55 GWd/tU, and cooling time of 50 years was determined as reference fuel for Westinghouse-type SFs; SF of PLUS7 with $^{235}U$ enrichment of 4.5 wt%, discharge burnup of 55 GWd/tU, and cooling time of 45 years was determined as reference fuel for Korean-type SFs.

• Food Science and Industry
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• v.55 no.2
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• pp.188-202
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• 2022

In the insect industry, as the scope of application of insects is expanded from pet insects and natural enemies to feed, edible and medicinal insects, the demand for quality control of insect raw materials is increasing, and interest in securing the safety of insect products is increasing. In the process of expanding the industrial scale, controlling the temperature and humidity and air quality in the insect breeding room and preventing the spread of pathogens and other pollutants are important success factors. It requires a controlled environment under the operating system. European commercial insect breeding facilities have attracted considerable investor interest, and insect companies are building large-scale production facilities, which became possible after the EU approved the use of insect protein as feedstock for fish farming in July 2017. Other fields, such as food and medicine, have also accelerated the application of cutting-edge technology. In the future, the global insect industry will purchase eggs or small larvae from suppliers and a system that focuses on the larval fattening, i.e., production raw material, until the insects mature, and a system that handles the entire production process from egg laying, harvesting, and initial pre-treatment of larvae., increasingly subdivided into large-scale production systems that cover all stages of insect larvae production and further processing steps such as milling, fat removal and protein or fat fractionation. In Korea, research and development of insect smart factory farms using artificial intelligence and ICT is accelerating, so insects can be used as carbon-free materials in secondary industries such as natural plastics or natural molding materials as well as existing feed and food. A Korean-style customized breeding system for shortening the breeding period or enhancing functionality is expected to be developed soon.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.24-35
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• 2023

Recently, the Ministry of Land, Infrastructure and Transport presented the '6th Construction Technology Promotion Basic Plan' and 'Smart Construction Revitalization Plan (2022.7.20)'. Off-Site Construction (OSC), which involves construction and production of PC (Precast Concrete) and Modular, etc., has advantages in shortening the construction period, reducing costs, improving quality, reducing construction waste, and reducing safety accidents. However, the construction cost is high compared to the traditional RC construction method, which has hindered its utilization and spread. In this study, OSC utilization was improved. An economic analysis indicator and methodology that can support decision-making in the planning and design stages for multi-unit housing were proposed. The factors used in the economic analysis of OSC (based on the PC method) of apartment houses were reviewed. As for the indicators used in the cost and benefit section, 'Construction Period', 'Disaster Occurrence', 'Waste Generation', and 'Greenhouse gas Emission', which reflect the technical advantages of OSC, were derived. In addition, a scenario analysis was conducted based on actual apartment housing case data for the presented economic analysis indicators and benefit calculation standards. The level of benefit that offsets the difference between the existing RC construction method and the construction cost was reviewed. In future studies, it will be necessary to conduct additional case studies to apply the measurement criteria for detailed indicators and supplement the benefit indicators.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.4
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• pp.31-37
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• 2010

Livestock manures have a potential to be a valuable resource with an efficient treatment. In Korea, 42 million tons of livestock manure were generated in 2008, and 84 % of them were used for compost and liquid fertilizer production. Recently recycling of livestock manure for biogas production through anaerobic digestion is increasing, but its utilization in agriculture is still uncertified. In this study, there was applied co-digestate to the paddy for rice cultivation based on N supplement. Co-digestate was fertilizer fermented with pig slurry and food waste combined with the ratio of 70:30(v:v) in its volumetric basis. For assessing the safety of co-digestate, it was monitored the contents of co-digestate for seasonal variation, resulted in no potential harm to the soil and plant by heavy metals. The results showed that soil applied with co-digestate was increased in exchangeable potassium, copper and zinc mainly due to the high rate of pig slurry in co-digestate applied. Considering high salt content due to the combination with food waste, strict quality assurances are needed for safe application to arable land though it has valuable fertilizer nutrient. Leachate after treatment showed that the concentration of nitrate nitrogen washed out within two weeks. Considering the salt accumulation results in soil, it is highly recommended that the application rate of co-digestate should not exceed the crop fertilization rate based on N supplement. With these results, it was concluded that co-digestate could be used as an alternative fertilizer for chemical fertilizer. More study is needed for the long-term effects of co-digestate application on the soil and water environment.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.245-245
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• 2010

우리나라 생활폐기물 중 음식물쓰레기는 가장 많은 부분을 차지하고 있다. 또한, 음식물쓰레기에서 발생되는 음폐수의 발생량은 8,926톤/일에 달하고 있지만, 이 중 극히 일부만이 하수처리장 등에서 병합 처리되고 있고 대부분은 해양 투기되고 있는 실정이다. 이에 본 연구에서는 독일 GBU사로부터 중온/습식/이상 혐기성 소화 기술을 도입하여 HADS Pilot Plant를 설치하였고, 2008년 3월부터 국내 음폐수 및 음식물쓰레기에 적합한 최적의 운전기술을 확보하기 위한 Pilot Test를 실시하였다. 본 실험에 사용된 HADS Pilot Plant는 산발효조($6m^3$), 메탄발효조($50m^3$), 안정화조/가스저장조($40m^3$)그리고 가스 소각기로 구성되어 있다. 그리고 적용 음폐수 및 음식물쓰레기는 경기도 Y군에 위치한 사료화 시설에 반입되는 것을 이용하였는데 음폐수는 평균 TS 13.5%, VS 80%, pH $3.7{\pm}0.2$의 성상을 나타내었다. 이를 이용해 계단식으로 유기물 부하를 증가시키면서 $4kgVS/m^3/d$까지 적용하며 중온 상태에서 혐기성 소화를 실시한 결과, $0.8Nm^3/kgVS_{rem}/d$의 바이오가스 회수 및 85%의 VS 감량이 가능함을 확인하였다. 그리고 음식물쓰레기는 음폐수와 달리 1차 파쇄/선별기 및 배관상에 설치되는 2차 미세파쇄/선별기를 통한 전처리를 실시하였고, 1차 파쇄/선별 후 평균적으로 TS가 17.4%, VS는 81%, pH는 $3.85{\pm}0.2$의 성상을 나타내는 음식물쓰레기를 2차 미세파쇄/선별기를 거쳐 Pilot Plant의 산발효조에 투입하여 중온상태에서 혐기성 소화를 실시하였다. 음폐수 적용시와 마찬가지로 계단식으로 유기물 부하를 증량하면서 $4kgVS/m^3/d$까지 적용하여 운전하였고, 그 결과 약 $0.9{\sim}1.2Nm^3/kgVS_{rem}/d$의 바이오가스 회수와 85~87%의 VS 감량 효율을 확인하였다. 음폐수와 음식물쓰레기의 혐기성 소화 실험 결과, 제거된 VS량을 기준으로 보았을 때, 음식물쓰레기에서 더 많은 바이오가스 발생하였는데 이는 음식물쓰레기에 존재하는 고형물이 미생물들의 서식 공간으로 활용됨에 따라 혐기성 소화 과정에서 일어나는 혼합 발효 및 공영양 대사가 음폐수 대비 좀 더 수월하게 일어날 수 있게 된 데에 따른 결과라고 생각된다. 당사의 HADS Pilot Plant test에서는 계단식의 순차적인 유기물 부하 증량과 총VFA/총 알카리도 비율을 0.3~0.4 수준이하로 유지하며 운전함에 따라 음폐수와 음식물 모두에서 안정적으로 $4kgVS/m^3/d$까지의 유기물 부하 적용이 가능하였다. 또한, 생산된 바이오가스 내 메탄의 함량은 60~65%를 유지하였으며, 메탄발효조의 pH는 별도의 조절이 없이도 운전기간 동안 평균 7.8~7.9 수준을 유지하였다. 이처럼 pH 3.7~3.8의 음폐수 또는 음식물쓰레기의 투입에도 안정적인 완충능력을 보여준 것은 소화조 내에서 기질로부터 분해되어져 나오는 암모니아와 이산화탄소가 강력한 버퍼 시스템을 구축하고 있음에 따른 결과로 사료된다. 그리고 음폐수와 음식물쓰레기의 경우 모두 85%이상의 높은 VS 제거율을 보여주었는데 이는 당사의 HADS Pilot Plant 소화조의 구조가 내통과 외통으로 구분되어져 있음에 따라 plug flow + CSTR의 특징을 가짐에 따른 결과로 판단된다. 상기한 결과를 바탕으로 향후에는 $5kgVS/m^3/d$ 수준의 유기물 부하 적용운전도 계획하고 있다.

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.670-678
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• 2003

Recently, since industrial waste and life waste leaped into a pollution source, the building material used now a days is striking the limit. The purpose of this paper is to investigate an application of recycled coal ash using non-sintering method in the construction field. Accordingly, compressive strength, elastic modulus and drying shrinkage were experimentally studied for hardened coal ash using the non-sintering method. Also, Lineweaver and Burk method were applied to the regression analysis of drying shrinkage for the proposal equation. Elastic modulus, compressive strength of material become the basis properties of structural design. And these properties by age for hardened coal ash are important because of change by pozzolan reaction. This hardened coal ash is weak for tensile stress like that of concrete. And drying shrinkage is very important factor to make huge tensile force in early age. In the results, although some differences were shown when comparing coal ash with mortar or concrete, the application as a building material turned out to be possible if further researches were carried out. And the shrinkage characteristic of hardened coal-ash reveals to be similar to that of moderate heat cement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.173-179
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• 2014

This is an experimental study for recycling coal ash left over from coal use as a potential fine aggregate in concrete. Coal ash is generally divided into either fly ash or bottom ash. Fly ash has been utilized as a substitution material for cement in concrete mixes. On the other hand, bottom ash has the problem of low recycling rates, and thus it has been primarily reclaimed. This study partially substituted fine concrete aggregates with bottom ash to increase its application rate and therefore its recycling rate; its suitability for this purpose was confirmed. The concrete's workability dropped noticeably with increasing bottom ash content when a fixed water-cement ratio of concrete mix was used. Thus, concrete mixes with higher ratio levels are required. To address this problem, concrete was mixed using a polycarboxylate high-range water reducing agent. The fluidity and air entrainment immediately after mixing the concrete and 1 h after mixing were measured, thereby replicating the time concrete is placed in the field when produced either in a ready-mixed concrete or in a batch plant. As a result of this research, the workability and air entrainment were maintained 1 h after mixing for a concrete mixture with approximately 30% of its fine concrete aggregates substituted with the bottom ash. A slight drop in compression strength was seen; however, this confirmed that potential of using bottom ash as a fine aggregate in concrete.