• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.124-131
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• 1996

The use of small hemispherical high-speed precision bearing has increased drastically these days in the field of computer disk driver, highteech devices as well as communication and electronic device drivers. It was suggested that the new polishing process adopting the diamond grinding wheel and polishing tool instead of multi stage lapping processes, which enables the mass production of the bearing by reduction of polishing time. Polishing mechanism was analysed and the results were applied to the design and manufacturing of the polishing system. Experiments for selection of optimal polishing conditions were carried out using the polishing system.

• Applied Biological Chemistry
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• v.41 no.7
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• pp.527-532
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• 1998

This study was aimed at the development of the rice product by fermentation of saccharified rice solution with Bifidobacterium. To optimize the preparation of saccharified rice solution for Bifidobacterium fermentation, various pretreatment conditions were established. Grinding for 30seconds by an impact mill was more efficient than any other grinding schemes tested. The preheating before gelatinization showed a positive effect for efficient saccharification, and its optimal conditions were at $60^{\circ}C$ for 45 min. The optimum gelatinization conditions were at $100^{\circ}C$ for 40 min. The optimum levels of enzymes for saccharification of rice were 0.135 unit/g rice powder for ${\alpha}-amylase$ and 3.375 unit/g rice powder for glucoamylase, respectively. The physico-chemical properties of the fermented product by a fastidious Bifidobacterium showed a great potential for a functional rice product. However, an improvement on its flavor was required, which might be achieved by the addition of various fruits and vegetables.

• Mycobiology
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• v.38 no.1
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• pp.33-38
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• 2010

We have successfully applied the nested PCR to detect Cylindrocarpon destructans, a major pathogen causing root rot disease from ginseng seedlings in our former study. The PCR assay, in this study, was used to detect the pathogen from soils. The nested PCR using internal transcribed spacer (ITS) 1, 4 primer set and Dest 1, 4 primer set maintained the specificity in soils containing various microorganisms. For a soil DNA extraction method targeting chlamydospores, when several cell wall disrupting methods were tested, the combination of lyophilization and grinding with glass beads, which broke almost all the chlamydospores, was the strongest. The DNA extraction method which was completed based on the above was simple and time-saving because of exclusion of unnecessary stages, and efficient to apply in soils. As three ginseng fields whose histories were known were analyzed, the PCR assay resulted as our expectation derived from the field information. The direct PCR method will be utilized as a reliable and rapid tool for detecting and monitoring C. destructans in ginseng fields.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.437-442
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• 2010

Sodium hydrogen sulphate ($NaHSO_4$), n-tetra butyl ammonium bromide (TBAB) as a phase transfer catalyst (PTC) in water, and 1-butyl-3-methyl imidazolium hydrogen sulphate [bmim]$HSO_4$ as ionic liquid (IL) has been used as a mild reaction promoter for the cyclocondensation of formalin, ${\beta}$-naphthol and aromatic amines to afford respective 2,3-dihydro-2-phenyl-1H-naphtho-[1,2-e] [1,3] oxazine derivatives. The present protocols are greener, high yielding and involved the nonchromatographic isolation procedure.

• Journal of the Korea Institute of Building Construction
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• v.2 no.2
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• pp.129-134
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• 2002

The strength and durability of concrete are affected by various factors such as the quality of material, mixing ratio, construction, the method of cure, time elapsed. the condition of test and etc., it is very difficult to pre-estimate the strength of concrete with the use of experimental specimen. The domestic standard of specimen cylindrical type and its sizes are both l0cm$\times$20cm and 15cm$\times$30cm, which are prescribed in KS F2405, and the loading speed is prescribed to test with 2~3kgf/$\textrm{cm}^2$ per second. The loading speed should have great effect on the compressive strength, but in reality in the construction site sometimes the loading speed is applied so dubiously that the value of the compressive strength can be unreliable. And the cross sectional area of a specimen should be level and smooth, otherwise it can be broken at a lower stress than the real strength through the eccentric or intensive working of the load. Capping should be carried out in order to measure the strength correctly. And used for capping are various materials such as capping compound, cement glue, plaster, mechanical grinding and etc. In this study, therefore, I have carried out an experiment on the relationship among the loading speed, the ratio of height to diameter of specimen, the method of capping, and the compressive strength, for the efficient quality control of concrete structures. So this study has been purposed to provide some basic data that can be used effectively at construction sites.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.5
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• pp.8-13
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• 2012

The flexography ink has disadvantage in a deinking process because it tends to form too fine particles in alkali condition to be removed in flotation deinking. The influence of pH conditions on the particle size of phthalocyanine cyan ink used for flexo-printing was investigated to see the effect of pH conditions on flexography ink dispersion. Flexography ink particles prepared by grinding dried ink films were used in this experiment. Greater reduction of the ink particle size was noticed under alkaline pH condition, which was attributed to dissolution of resin component of the ink. Adsorption behavior of flexography ink onto pigment particles was examined using clay and talc as substrate pigments. Pretreatment of inorganic pigments with a cationic poly-DADMAC increased the surface adsorption of flexography ink particles, which improved the removal of the inks by centrifugal sedimentation of inorganic pigments. Most efficient removal of the ink particles was achieved when an optimal addition level of the cationic polymer was used for pretreatment of inorganic pigments, and this optimal addition level corresponds to the surface saturation point of the polyelectrolyte. Adsorption of flexography ink particles onto inorganic pigments improved the ink removal in flotation deinking since the pigment particles has the optimal particle size for flotation deinking.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.376-380
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• 2018

The astaxanthin recovery efficiencies were compared in acetonitrile, acetone, methanol, dichloromethane : methanol (1:3, v/v) and ethylacetate : ethanol (1:1, v/v) as a extraction solvent after the grinding of the H. pluvialis cells. The astaxanthin extraction yield in acetone was 1.13~1.29 times higher than other extraction solvents. It was also found that 96.7% of astaxanthin accumulated in H. pluvialis could be recovered by a single extraction. Since astaxanthin exists mainly as astaxanthin esters in H. pluvialis, a gradient reversed-phase HPLC analysis was carried out for the separation of astaxanthin esters from the extracts of H. pluvialis. Among the astaxanthin inside the H. pluvialis cell, free astaxanthin was 45.9% and astaxanthin esters were the rest.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.685-692
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• 2016

A cutting head is an attachment on the front of an excavator that cuts or grinds rocks. Cutting tools, called pick cutters, are arranged on the surface of the cutting head. The exact arrangement and configuration of pick cutters is one of the most important factors in determining grinding efficiency. This study focuses on the problem of automation for pick arrangement design, in order to make the design process more efficient and convenient. Design automation was carried out using RecurDyn/ProcessNet, and it was composed of three parts: 'Drum set', 'Pick load', and 'Pick arrangement' sections. The presented method helps to decrease costs attributed to designing cutting heads and can be used to generate a wide range of attachment mechanisms.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.181-186
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• 2007

Despite of environmental problems(safety hazards), mechanical recycling of FRP boats, which involves shredding and grinding of the scrap FRP in a new product. is one of the simpler and more technically proven methods than incineration or reclamation ones. Because FRP is made up of reinforced fiber glass, it is very difficult to break into pieces. It also occurs secondary problem such as air pollution and unacceptable shredding noise level. The another urgent problem which is a serious barrier to FRP recycling is very limited reusable applications. This study is to propose a new method which is efficient and environment friendly waste FRP regenerating system. And it also have shown the polymer cement and fiber-reinforced concrete applications with the waste FRP.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.167-172
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• 2007

Since 1990s, these many researchers have been fully involved in developing recycling methods for FRP boats. There are four basic classes of recycling covered in the literature. the first is "Mechanical recycling" which involves shredding and grinding of the scrap FRP in a new product. Despite of the safety hazards, mechanical recycling is one of the simpler and more technically proven methods. Recent researchers should be more interested in these methods. It is fact that most of FRP wastes are depended on incineration or reclamation. Because it Is made up of reinforced fiber glass, it is very difficult to break into pieces. By the disposing of waste FRP this way, it also occurs secondary problem such as air pollution and unacceptable noise. This study is to propose a new method which is efficient and environment friendly waste FRP regenerating.