• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.630-635
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• 2016

In the prior work, we studied a ballast water treatment apparatus, which is secondary pollution free by using physical treatment of shear stress. The principle of this apparatus is smashing various microorganisms by shear stress generated between stationary outer cylinder and revolving inner cylinder. Because of various magnitude of shear stress according to the inner cylinder surface type and revolution speed, an appropriate surface type and optimum revolution speed should be studied by consecutive experiment to determine the reference data for commercial apparatus. Through a comparative study of disk type and cylinder type of ballast water treatment apparatus, cylinder type is turned out to be superb to disk type. In this study, we studied to determine the superior collaboration of cylinder type, groove type and knurling type of inner cylinder to non patterned outer cylinder, and to optimize the revolution speed and flow rate according to the gap between inner cylinder and outer cylinder. As a result, we could get perfect sterilization effect at groove type under the conditions of 250 mL/min of flow rate at 8,000 rpm and 500 mL/min of flow rate at 10,000 rpm respectively.

• Explosives and Blasting
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• v.28 no.1
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• pp.1-10
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• 2010

In blasting for lighting, fatigue behaviors of pillars such as destruction and deformation may occur due to blasting vibration and flyrock, which may cause collapses of cavities. This study aims to identify dynamic behavior of pillars to maintain efficient safety of cavities in large drafts. when they collide with flyrocks under blasting for the excavation. For the purpose, we compared ground vibration around pillar when flyrock collided with the pillar and that when explosive blast happened for the excavation. we conducted fragmentation analysis of the flyrock and compared impact vibration obtained from empirical equation with ground vibration obtained from regression analysis of real vibration data. also we compared those with results analyzed from numerical analysis.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.505-513
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• 2016

The qualitative distribution of a fractured aquifer was characterized by electrical resistivity surveying as a part of basic groundwater investigation in Jangseong. The results were then used to choose sites for observation wells. The locations and distributions of permeable discontinuities were studied by analyses of temperature logs, a borehole image-processing system (BIPS), and hydraulic pressure testing using a double packer. The pressure test showed that the size of the discontinuities correlated with the Lugeon value and the results of the temperature log. The results show that temperature measurement is an effective method to identify permeable discontinuities, with the temperature difference correlating with the size of the aperture of the discontinuity.

• Tunnel and Underground Space
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• v.24 no.2
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• pp.111-119
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• 2014

This study developed a Windows-based simulation program for selecting equipments in open-pit shovel-truck haulage systems. Visual Basic.NET 2012 was used to develop the graphic user interface (GUI) and the GPSS/H simulation language was utilized to implement the simulation engine of program. When users establish simulation parameters through the GUI, the program calls the simulation engine to perform the simulations repeatedly. Then, it finds the optimal fleet of equipments required for operating the open-pit shovel-truck haulage systems efficiently. Application of the program to the Ssangyong open-pit limestone mine, Gangwon-do, Korea, showed that the daily average profit of shovel-truck haulage operation can be maximized (i.e. 88,552 USD) under following conditions: (a) 4 trucks are dispatched into each loading point and (b) a crusher with capacity of 1,500tph is utilized.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.125.1-125
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• 2003

호박은 다른 과채류에 비해 기후조건에 대한 적용범위가 넓고, 한국의 기후 풍토하에서 잠재생산 가능성이 대단히 높은 작목의 하나로 간주되고 있으며, 다른 박과 채소보다 병이 심하지 않고 약재를 살포할 필요가 거의 없으므로 무공해 식품으로도 그 가치가 높은 것으로 평가되고 있다. 최근 국민 식생활 패턴이 고급화 됨에 따라 건강을 중요시하는 소비자가 급증하면서 약품이 아닌 식품으로 인체의 조절기능에 초점이 맞춘 다양한 기능성 식품이 생산되고 있는 실정이며, 이 중 녹황색 채소류의 항산화, 항암효과가 알려지고 있어 늙은 호박을 이용한 새로운 형태의 가공제품은 향후 소비자의 구매욕구를 충동하기에 충분할 것으로 판단된다. 따라서 이러한 호박을 이용하여 가공제품을 생산하기 위한 기초자료로서 추출조건에 따른 품질변화를 모니터링하고자 하였다. 호박의 전처리의 경우 박피유무에 큰 차이가 없으므로 공정단계를 최소화하기 위해 박피를 하지 않고 사용하였으며, 파쇄의 형태는 깍둑썰기(4$\times$4$\times$4㎤)를 하여 추출조건에 사용하였다. 추출온도의 경우 호박자체의 색을 유지하는데 효율적인 95$^{\circ}C$에서 행하였다. 시료에 대한 용매비 및 추출시간에 따른 품질의 변화가 많으므로 시료에 대한 용매비(10, 20, 30, 40 50g/100$m\ell$) 및 추출시간(1, 2, 3, 4, 5 hr)에 따른 중심합성실험계획으로 추출하였다. 추출조건에 따른 추출물에 대하여 수율, 당도, 갈색도 및 탁도를 측정하여 시료에 대한 용매비 및 추출시간에 따른 반응표면분석을 실시하였다. 영향도를 분석한 결과 수율은 추출시간에 영향을 많이 받는 것으로 나타났으며, 총당 및 갈색도는 시료에 대한 용매비에 영향을 많이 받으며 탁도의 경우 두 조건 모두에 영향을 받은 것으로 나타났다. 수율에 대한 최적 추출조건은 호박량 10.03% 및 추출시간 2.89hr일 때 가장 높은 수율로 예측이 되었으며, 갈색도의 경우 호박량 15.21% 및 추출시간 1.65hr에서 최소로 나타났다.

• Explosives and Blasting
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• v.26 no.2
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• pp.29-37
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• 2008

In general, the size of tunnel cross section in construction site is $50{\sim}200m^2$. But, electric cable tunnel, telecommunication cable tunnel, mine tunnel. Waterproof tunnel have small cross section less than $20m^2$. There are so many problem at small sectional tunnel: restriction of equipment, dead pressure by precompression, loss of efficiency, increase of work time. Especially, explosives remainder by precompression of previous detonation is serious problem. To find its measures of dead pressure (explosives remainder), the following series of progress have been conducted: (1) survey of previous study (2) investigate causes of dead pressure (3) set up of its measures (4) application and appraisal at tunnel site. The measures, change of cut pattern, hole space over 40cm, adjustment of delay time, are proved by experimental results.

• Tunnel and Underground Space
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• v.9 no.1
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• pp.64-71
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• 1999

A numerical analysis was performed to investigate the effects of notched blasthole in controlling the fracture plane. Analyzed were elastic and elasto-plastic response of rock, and fracture propagation under static and dynamic load conditions. Results showed that the region exceeding the tensile strength extended up to three times the radius of a normal blasthole in elastic analysis, while fifteen times in elasto-plastic analysis. It was shown that a crack was driven from the notch tip up to the distance of 23 times the hole radius in the case of a notched blasthole with a notch of 5 mm in depth and 30 mm in length.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.501-505
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• 2007

Organophosphorus hydrolase (OPH) expressed from recombinant Escherichia coli was used to biodegrade organophosphate insecticide coumaphos which has a very high toxicity in mammalian cells. To improve the productivity of OPH, the effects of nonionic surfactants (Tween 20, PEG 1000) and organic solvents, such as glycerol, propanol, and ethanol, were investigated in the strain culture. The maximum OPH was produced when the 0.25% of Tween 20 and 0.5% of glycerol were added to the medium. As the OPH obtained from disrupt-cell process by ultrasound treatment was used, the biodegradation efficiencies of 0.2, 0.5, 1.0 and 2.0 mM coumaphos were 100, 88, 84 and 78%, respectively. A novel method developed in this study could be applied to the biodetoxification technology in the contaminated region with various coumaphos concentration.

• Resources Recycling
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• v.16 no.5
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• pp.25-30
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• 2007

In Korea, reutilization of construction waste is gaining attention as construction waste generated increases continuously. Currently, the concrete waste is simply crushed and used as a low value application such as paving, back filling, etc. To meet the demand of aggregate for construction and the resource efficiently, production of high quality recycled aggregate is necessary. Therefore, in this study, a better process for production of high quality recycled aggregate was developed using combination of heat pretreatment and autogenous milling. Test results showed that the recycled aggregate has a density of $2.5\;g/cm^3$ and a water absorption ratio of 3.0%, which meet the specification of the first class of KS F 2573. Currently, a pilot scale autogenous mill is being constructed and tests will be further conducted to develop a commerce-scale process.

• Journal of Korean Society of Forest Science
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• v.106 no.1
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• pp.54-62
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• 2017

This study was carried to develop the chip-harvester and to analysis the operation productivity and cost for effective collection and forwarding of forest biomass. Main target specification of chip-harvester is speed of 8km/h, maximum climbing capacity of $30^{\circ}$ and maximum load capability of 2000 kg. Body structure is articulate type to reduce turning radius. Driving equipment is six-wheel drive, and a rear wheel is tandem bogie type to increase grip force. As a result of the driving test about developed chip-harvester, driving speed was 6.9 km/hr and 8.1 km/hr in ${\pm}10%$ slope with loaded and 7.3 km/hr and 7.9 km/hr in ${\pm}10%$ slope without load. As a result of the operation productivity and cost, operation productivity of grinding and forwarding was approximately $10m^3$ per day, and operation cost was 393,126 won per day.