• 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.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.1
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• pp.29-37
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• 2006

In remediation of the contaminated soil, it requires to select at least more than two remediation technologies depending on the fate and transport phenomena through complicated reactions in soil matrix. Therefore, methodologies related to develop the integrated remediation technology were reviewed for agricultural soils contaminated with heavy metals. Pneumatic fracturing is necessary to implement deficiency because soil washing is not effective to remove heavy metals in the subsurface soil. But it needs to evaluate the characteristics such as essential data and factors of designated technology in order to effectively apply them in the site. In the remediation site, the important soil physical and chemical factors to be considered are hydrology, porosity, soil texture and structure, types and concentrations of the contaminants, and fate and its transport properties. However, the integrated technology can be restrictive by advective flux in the area which remediation is highly effective although both soil washing and pneumatic fracturing were applied simultaneously in the site. Therefore, we need to understand flow pathways of the target contaminants in the subsurface soils, that includes kinetic desorption and flux, predictive simulation modeling, and complicated reaction in heterogenous soil.

• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.395-403
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• 2022

In this study, we identified that the fermentation of Korean indigenous probiotics and red ginseng produced ginsenoside compound K (CK) from major ginsenosides. Based on whole genome sequencing of 19 probiotics species, β-glucosidase, α-arabinofuranosidase, β-xylosidase, and α-rhamnosidase related to bioconversion of ginsenosides are identified in the genome of 19 species, 3 species, 6 species, and 8 species, respectively. Among the 19 probiotics species, Bifidobacterium longum CBT BG7 converted from ginsenoside Rb1 to CK, and both B. breve CBT BR3 and B. lactis CBT BL3 converted ginsenoside Rb1 to Rd. The final concentration and yield of ginsenoside F2 and CK were higher in the fermentation with the nondisrupted cells than with disrupted cells. The combination of both CBT BG7 and BL3, and CBT BG7 and BR3 showed higher amounts of F2 than CBT BG7 only. CBT BG7 with adding α-amylase increased the amounts of F2. In this study, we identified that the fermentation of both Korean indigenous probiotic bacteria CBT BG7, BR3 and BL3, and red gingseng is able to produce CK, a bioactive compound that promotes health benefits.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1083-1096
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• 2015

This study utilised Computational Fluid Dynamics(CFD) for preliminary assessment of mixing efficiencies of 2-phase fluids in a pipe at which a slurry flow and an injected solidifier join, for the purposes of reducing trial-and-error-based instances of physical experiments and conducting the overall research in an economical way. Using OpenFOAM$^{(R)}$, we simulated behavior of 3-phase fluids under 18 different settings generated by changing diameters of a dredged soil transportation pipe, a quality improving material injection pipe and the confluence angle. While difference in mixing efficiencies amongst the instances was insignificant, discernible boundary layers amongst the materials were observed in all of the instances. In order to break the boundary layers, we designed a substructure inside a pipe and found out that it could remarkably improve mixing efficiencies particularly for short distance applications.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.387-393
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• 2006

This paper introduces the combination of two blasting methods applied to reduce blast-vibration and increase blast efficiency. NDC (New Deck Charge) blasting method using air deck effect with separation tube made of paper was effective to reduce blast-vibration, while blast efficiency was decreased a little in the bottom of a blasthole. Wide Space blasting method has an advantage to control the fragmentation and to increase blast efficiency over conventional blasting methods. In this study new blasting method combining NDC blasting method and Wide Space blasting method was applied to the field, it was confirmed to reduce blast-vibration and increase blast efficiency. It is expected to make useful blasting method to cover the public complaints and to shorten construction time by accumulating blasting data using new method with various conditions.

• Explosives and Blasting
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• v.22 no.1
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• pp.23-32
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• 2004

터널 발파를 원활히 수행하기 위해서는 암반조건에 적합한 합리적인 설계와 정밀한 천공, 정확한 기폭초시가 기본요소로서 이는 현재 국내 터널 설계.시공 기술 및 기자재의 발달로 만족할 만한 성과를 얻을 수 있다. 특히. 터널발파에서 정확한 기폭초시 부여는 굴진율 및 버럭 파쇄율, 굴착예정선 미려도, 잔여 암반 손상도 등의 시공성에서 뿐만 아니라 소음 및 진동 발생율을 좌우하는 환경적인 측면에서 매우 중요한 요소이다. 기폭요소는 최초 도화선을 활용한 공업뇌관에서 전기뇌관, 비전기식뇌관의 순으로 기폭안전성과 정밀성 면에서 눈부신 성장을 이룩하여 왔으며 특히, 90년대 초에 개발되어 전 세계적으로 최근까지 지속적으로 사용량이 급증하고 있는 전자뇌관은 기폭방식에 일대혁신을 이루었다. 전자기폭 시스템은 기존뇌관의 초시를 결정하는 화약성분의 지연요소 대신에 IC board(전자회로)에 의한 Digital timer로 신호를 발생하여 초시를 결정하는 방식이다. 본 논문에서는 국내 최초로 전자기폭시스템을 활용하여 2003년 9원 23일에서 동년 11월 2일까지 강원도 양구 지역의 $\bigcirc\bigcirc$터널에 전자뇌관을 이용한 시험발파를 실시하였고, 발파에 의한 진동 등을 조사하여 그 효율성을 검토하였다. 이를 위해 전자뇌관의 특성과 장점을 최대한 샅리기 위하여 각공을 발파하는 방식, 즉 1지발에 1공을 발파하는 방식을 채택하고 일반 뇌관과 전자뇌관으로 설계를 하여 각각의 발파효율을 비교하여 보았다. 그 결과 발파진동의 경우 기존뇌관을 이용하여 1공씩을 1지발로 발파를 한 경우에는 18~56%의 진동저감 효과가 있었고. 본선 설계에 의해 진행된 발파에 비하여는 최대 70% 이상의 진동저감 효과가 있는 것으로 나타났다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.2
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• pp.185-191
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• 2008

Today, Large and bigger underground construction are increased. In this study, Blating used electronic detonation (OBM Method) and non-electric detonation are carried out. Through comparison with two method, reduction of vibration and noise and efficiency of construction are investigated. As a result of this study, using electronic detonation is shown that it can control lower vibration and noise level, and better HCF, mucfile, advance rate and fragmentation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.494-503
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• 1986

본 연구에서는 저강도.고연성재인 일반구조용압연강 SB41의 평골 CT 시험편과 양측면홈이 있는 CT시험편을 사용하여 ASTM R유선법, JSME R유선법,SZW법, 초음파법 및 전입차법에 따라 J$_{IC}$를 종합적으로 평가하였다. 복수시험편법인 ASTM 및 JSME 및 JSME R유선법을 상호 비교고찰하므로써 저강도.고연성재에 대한 파환인성평가 의 적용한계를 명확히 하였으며 단일시험편법인 초음파 및 전입차시험법은 효율적이고 간편한 J$_{IC}$평가법임을 확인하였다.

• Explosives and Blasting
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• v.18 no.3
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• pp.29-40
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• 2000

Emulan은 ANFO와 bulk Emulsion(Emulite)의 흔합물로서 ANFO입자 사이의 공간은 내수성을 가진 Emulite로 채워지기 때문에 에너지와 밀도가 확실하게 증가하며 뛰어난 내수성을 가진다. 따라서 높은 장전밀도와 고 함유 에너지로 인하여 ANFO 대비 천공 미터당 암석 파쇄량을 40 %이상 증가시킬 수 있으며 저항선과 공간격을 각각 20%이상 증가시킬 수 있다. 특히, 습윤상태가 심한 장소에서 ANFO를 대신하여 가장 경제적인 폭약임이 확인되었다. 본 연구에서는 최신 Bulk-type의 폭약(Emulan)과 AFPO 및 Emulsion계 폭약을 각각 사용하여 현장의 적용성, 상호 발파효과 및 효율성과 경제성 비교를 통하여 앞으로의 대규모 노천현장이나 석산에서 보다 적절하게 사용할 수 있는 화약류에 대하여 알아보고자 하였다.