• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.84-89
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• 2003

The purpose of this study was to evaluate and improve the pre-treatment facility for foodwaste and sewage sludge mixture treatment. The process of foodwaste pre-treatment consists of storage, classification with crushing, and thickening. The effluent of sewage treatment facility was used as the diluting and washing water. The panicle size of foodwaste after pre-treatment was almost under 2mm, the mixture of foodwastes and sewage sludge showed an advantage to the anaerobic digestion. The amount of gas production increased from 0.8ton/day ($CH_4$ : 0.5ton/day) to 3.5ton/day ($CH_4$ : 2.3ton/day) after the anaerobic digestion of the foodwastes and sewage sludge mixture. The amount of sludge cake increased from 11.2ton/day to 21.2ton/day. Therefore, the proper operation of the foodwaste pre-treatment facility was contributed to the efficient anaerobic digestion of foodwaste and sewage sludge mixture treatment.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.29-34
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• 2002

An experiment was conducted to evaluate shattered industrial polyurethane (PUR) and cellular glass foam (CGF) as growth medium components. Pot chrysanthemum 'Pink Pixie Time 'was cuttured in media containing various volume ratios of PUR, CGF, peatmoss, coir, and perlite. Before plant culture, pH and EC of media were determined. Container capacity (%) was low in perlite and CGF-containing media, but it increased when incorporation ratio of peatmoss or coir was increased. pH was stable between 5.0 and 6.3, but was high in coir-contaning media as compared to other media tested. EC was very high in coir-containing media. Hight at 34 days after planting was the greatest in media containing CGF, and number. of leaves was similar among treatments. Growth in PUR-containinly media was poorer than that in the other media, with some leaf edge burning. Trends in growth measured at 97 days after planting was similar to that measured at 34 days after planting.

• Journal of the Korean Geotechnical Society
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• v.35 no.10
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• pp.33-45
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• 2019

In this study, in order to recycle a large amount of rocks and weathered mudstones produced by civil engineering projects such as railways and highways, as materials for roadbeds or embankment materials, circumferential specimens with a diameter of 5 cm and a height of 10 cm were made. A mudstone that weathered rapidly during rainfall was collected from Pohang construction sites. The weathered mudstone passed through a 2 mm sieve. It was prepared with the cement ratio, the sand ratio, curing condition and curing days. Three specimens were prepared according to each condition and then the unconfined compressive test, durability test and SEM analysis were performed to evaluate the engineering properties of the cemented soil. In the case of 28 days cured specimen, the strength of under-water cured specimens was 32-55% and the durability index was about 15% higher than air cured specimens. In addition, when the CR increased from 8% to 16%, the unconfined compressive strength (UCS) of pure mudstone cemented soil under water increased by about 1.6 times and the durability index increased by about 1.9 times. When the SR increased from 0% to 50%, the UCS of the specimen with SR = 10% was slightly less than or equal to specimen with SR = 0%. Then, as the SR became 30-50%, the UCS increased up to 51%. Unlike the UCS, the durability index increased continuously as the SR increased. As a result of SEM analysis, when SR was 50% rather than SR = 0%, the contact between sand particles increased and they were connected to each other. Such contact between these particles resulted in the increase of strength.

• Resources Recycling
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• v.12 no.3
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• pp.3-12
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• 2003

Physical separation containing grinding, sieving, dry magnetic separation and air classification were carried out in order to recover Ta anode from waste Ta condenser. Roll crusher wat used for the liberation of resin and metals in closed circuit system. The liberation between Ta anode and resin was easily achieved, whereat some of metals did not liberated from the Ta anode when the waste condenser was crushed below 8 mesh. When the crushed sample were divided into 8/10 mesh, 10/18 mesh and -18 mesh, metals was mainly remained in 8/10 mesh in contrast to Ta anode was in +18 mesh. It was shown that resin was more easily crushed rather than metals from the result of that resin content was 71.5％ in -18 mesh. The liberation efficiency was different with the input size of the crushed sample and average efficiency was 62.3% due to the locked Ta anode particles. The results of air classification test for the crushed samples showed that optimal air flow are 39㎥/h, 32㎥/h, 20㎥/h. respectively. When the sample were separated with optimal condition, 94.45％ Ta anode containing 97.47 wt.％ Ta anode, 0.93 wt.％ resin. 1.61 wt.％ metal was recovered with 49.39 wt.％ yield.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.103-114
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• 2007

Sands distributed in Jeju island's coastal areas, Korea, can be classified as silicate sand derived from volcanic rock, carbonate sand derived from shells, and mixed sands containing both silicate and carbonate sands. These three types of sands typically exist in Jeju coastal areas. Samples of silicate, carbonate and mixed sands were obtained from Samyang beach, Gimnyeong beach, and Jeju harbor area, respectively. Compression tests were conducted to assess the compression characteristics of these sands. As a result of these tests, each sand showed different behaviors. For Samyang beach sand, it appeared that initial compression is a larger than the other two sands. For Cimnyeong and Jeju harbor sands, however, the additional compression occurred after initial compression. This could result from the crushing, shattering, and rearrangement of sand particles. In addition, settlement behavior of Jeju harbor ground according to the construction stages was analyzed using the measured data. It showed that in addition to the initial elastic compression, a considerable additional compression occurred with time. The settlements of Jeju harbor ground were predicted by using the elastic settlement calculation methods (empirical methods) and the compression test method. The empirical methods, which did not consider the crushing, shattering, and rearrangement of particles could show smaller result than that occurring actually.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.177-184
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• 2024

This study was conducted to find a way to reduce the production of cakes generated in the domestic aggregate production process. Cakes from 8 wet aggregate producers were collected and particle size was analyzed. Samples were collected step by step from an aggregate producer A, particle size analysis was performed, and the material balance was calculated before and after an sand recovery unit by modeling the production process. As a result of the particle size analysis of eight cakes, one sample contained 50% sand, and the rest contained about 5% to 25% sand. The results showing that the cake contained a variety of sand in cakes may indicate that the recovery efficiency of the sand recovery units in the field varied. Sieve analysis of the samples showed that the generation of sand particles increased 2.8 times during the third crushing compared to the second crushing, and more cake particles were generated. As a result of simulating the sand recovery unit model, the lower the cut point of the cyclone and dewatering screen, the higher the sand production and the less cake production appeared. In order to reduce the production of cake in the field, it was determined that an optimal operation of the sand recovery unit was necessary in the aggregate production process.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.487-502
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• 2012

This paper is focused on mineral compositions, microstructures and distributional characters of remained grains in the fault rocks collected from a fault developed in Yongdang-ri, Yangbuk-myeon, Gyeongju City, Korea, using X-ray diffraction (XRD), optical microscope, laser grain size analysis and fractal dimension analysis methods. The exposed fault core zone is about 1.5 meter thick. On the average, the breccia zone is 1.2 meter and the gouge zone is 20cm thick, respectively. XRD results show that the breccia zone consists predominantly of rock-forming minerals including quartz and feldspar, but the gouge zone consists of abundant clay minerals such as chlorite, illite and kaolinite. Mineral vein, pyrite and altered minerals commonly observed in the fault rock support evidence of fault activity associated with hydrothermal alteration. Fractal dimensions based on box counting, image analysis and laser particle analysis suggest that mineral grains in the fault rock underwent fracturing process as well as abrasion that gave rise to diminution of grains during the fault activity. Fractal dimensions(D-values) calculated by three methods gradually increase from the breccia zone to the gouge zone which has commonly high D-values. There are no noticeable changes in D-values in the gouge zone with trend being constant. It means that the bulk-crushing process of mineral grains in the breccia zone was predominant, whereas abrasion of mineral grains in the gouge zone took place by continuous fault activity. It means that the bulk-crushing process of mineral grains in the breccia zone was predominant, whereas abrasion of mineral grains in the gouge zone took place by continuous fault activity. Mineral compositions in the fault zone and peculiar trends in grain distribution indicate that multiple fault activity had a considerable influence on the evolution of fault zones, together with hydrothermal alteration. Meanwhile, fractal dimension values(D) in the fault rock should be used with caution because there is possibility that different values are unexpectedly obtained depending on the measurement methods available even in the same sample.

• Geotechnical Engineering
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• v.13 no.6
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• pp.13-24
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• 1997

In Korea, granite is abundant and occupies around two-thirds of the country's ground. Bven though weathered granite residual soils are widely distributed, undisturbed sampling of this soil is extremely difficult because of the particultate structure. This difficulty has kept away the researchers from investigating !he deformational characteristics of weathered granite residual soil. Thus, a special undisturbed sampling device was developed and undisturbed samples were prepared for triaxial compression (TX), resonant column(RC), and torsional shear (75) tests. Local deformation transducer (LDT) was fabricated for internal strain measurements during TX tests. Both undisturbed samples and statically compacted samples of same density were tested by using TX with LDT, RC, and 75 test equipments. The behaviour of statically compacted specimens was almost the same as that of undisturbed samples in the strain ranges below 1 percent. The stiffness and strength decreased with increasing degree of weathering. In case of undisturbed specimens, strains at failure are widely varied from 2 percent to 11 percent, and planes of failure are irrelevant to the angle of internal friction due to the inhomogeneous nature.

• Resources Recycling
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• v.27 no.1
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• pp.55-63
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• 2018

Physical property changes of printed circuit board (PCB) according to heat treatment conditions were investigated. The heat treatment was carried out in air and nitrogen atmosphere at temperature range from $200^{\circ}C$ to $325^{\circ}C$. Thermogravimetric analysis showed that the PCB was pyrolyzed in two steps. The thickness of PCB expanded by 11~28% at about $300^{\circ}C$ in both air and nitrogen atmosphere as layer disintegration occurred. Mechanical strength of PCB decreased from 338.4 MPa to 20.3~40.2 MPa due to the delamination caused by the heat treatment. The heated printed circuit boards were crushed and sieved for analysis of density distribution and liberation degree of copper according to particle size. As a result of the density distribution measurement, non metallic particles and copper particles were concentrated into different size range, respectively. The liberation degree of copper was improved from 9.3% to 100% at size range of $1,400{\sim}2,000{\mu}m$ by heat treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.91-91
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• 2014

2002년 21세기 프론티어 연구개발사업으로 착수한 양성자기반공학기술개발사업이 2012년말 완료되었다. 이 사업을 통하여 이온원, RFQ, DTL, 초전도 가속관, 빔라인, 고주파 시스템, 제어 시스템 등 양성자 및 이온 가속기의 핵심 요소기술을 개발하고 100 MeV 선형 양성자가속기 및 이온가속기를 제작하여 경주에건설한 양성자속기연구센터에 설치하고 사업을 마무리하였다. 2013년 상반기에 냉각시스템 등 부대시설의 시운전, 양성자가속기와 20 MeV 및 100 MeV 빔라인 각 1기를 포함한 모든 시설의 시운전을 마무리하고, 한국원자력안전기술원의 방사선안전시설검사를 거쳐 7월부터 운영을 착수하였다. 양성자가속기는 2013년말 까지 총 2,290 시간을 가동하여 937건의 이용자 빔 서비스를 제공하였다. 기체, 금속, 대전류 이온을 공급할 수 있는 이온가속기 3대는 기업체의 공정 및 제품개발을 위한 이용을 중심으로 622건의 이용자 빔 서비스를 제공하였다. 2014년도는 양성자가속기는 연간 2,500 시간 가동, 빔 서비스 1,100건을 목표로 하고 있으며, 현재 20 MeV 및 100 MeV 각 1기인 뿐인 빔라인 증설을 준비하고자 한다. 이온가속기는 상반기에만 이용자 빔 서비스를 제공하고 2014년 11월 완공될 빔이용연구동으로 이전 설치하여 보다 양질의 이온빔을 공급할 수 있도록 장치를 보완 할예정이다. 더불어 2015년에는 3 MeV 헬륨빔과 1 MeV 기체 이온빔을 제공할 수 있는 장치도 추가로 설치할 예정이다. 빔이용연구동 및 이온가속기 업그레드가 완료되면 보다 다양한 양질의 이온빔을공급하여, 특히 중소기업의 제품 개발에 도움을 줄 수 있도록노력할 예정이다. 양성자가속기연구센터는 장기 비전인 펄스형 중성자원의 구축을 실현하고자 노력을 지속할 것이다. 미국의 SNS 및 일본의 J-PARC 파쇄 중성자원은우수한 연구 성과를 생산하기 시작하였고 우리나라도 이에 대한 수요가 생겨나도 있다. 충분한 수요가 형성되면 이미 확보한 부지와 초전도 가속기 기술을 활용하여 단시간 내에 펄스형 중성자원 구축이 가능할 것이다. 펄스형 중성자원이 구축되면 양성자가속기연구센터는 당초 목표한 양성자, 중성자 및 다양한 종의 이온을 한 사이트에서 제공하여, 입자빔을 이용한 다양한 연구개발에서 상당한 시너지 효과를 낼 수 있을 것으로 기대한다.