• Journal of Environmental Science International
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• v.25 no.2
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• pp.231-238
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• 2016

In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%~40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.2
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• pp.288-297
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• 2000

This paper describes the results of an experimental investigation of the flow characteristics and the heat transfer rate on a surface by interaction of a pair of vortices. The test facility consists of a boundary-layer wind tunnel with a vortex introduced into the flow by half-delta wings(vortex generators) protruding from the surface. In order to control the strength of the two longitudinal vortices, the angles of attack of the vortex generators are varied from 20 degree to 45 degree, but spacings between the vortex generators are fixed to 4 cm. The 3-dimensional mean velocity downstream of the vortex generators is measured by a five-hole pressure probe, and the hue-capturing method using the thermochromatic liquid crystals has been used to provide the local distribution of the heat transfer coefficient. By using the method mentioned above, the following conclusions are obtained from the present experiment. The boundary layer is thinned in the regions where the secondary flow is directed toward the wall and thickened where it is directed away from the wall. The peak augmentation of the local heat transfer coefficient occurs in the downwash region near the point of minimum boundary-layer thickness. Streamwise distributions of averaged Stanton number on the measurement planes show very similar trends for all the cases(${\beta}=20^{circ},\;30^{\circ}\;and\;45^{\circ}$).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.2
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• pp.298-305
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• 2000

The flow characteristics and the heat transfer rate on a surface by interaction of a pair of vortices were studied experimentally. The test facility consisted of a boundary-layer wind tunnel with a vortex introduced into the flow by half-delta wings protruding from the surface. In order to control the strength of the longitudinal vortices, the angles of attack of the vortex generators were varied from - 20 degree to - 45 degree, but spacings between the vortex generators were fixed to 4 cm. The 3-dimensional mean velocity measurements were made using a five-hole pressure probe. Heat transfer measurements were made using the thermochromatic liquid to provide the local distribution of the heat transfer coefficient. Unlike common flow down, common flow up vortices moved toward the centerline as they developed and interacted strongly with each other but not with the boundary layer. Spanwise profiles of Stanton number were similar for ${\beta}=-20^{\circ}\;and\;-35^{\circ}$, but not similar for ${\beta}=-45^{\circ}$. The case of ${\beta}=-20^{\circ}\;and\;-35^{\circ}$ showed the two peak Stanton number, but the case of ${\beta}=-45^{\circ}$ showed the only one peak Stanton number.

• Korean Journal of Construction Engineering and Management
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• v.10 no.4
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• pp.151-164
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• 2009

Strategic alliances developed as formalized inter-organizational relationships are core vehicles to share information, resources and knowledge. The structural characteristics of strategic network constructed by strategic alliances have been important agenda in strategic management discipline. This paper has two folds in analysing the strategic network formulated by project level alliances in Korean construction industry. First, we investigate the strategic network using the tools and methods of social network analysis, such as centrality, cohesion, structural equivalence, and power law. Second, the performance of firms within networks are analysed longitudinally with panel data analysis. We have found that the strategic networks in this industry has scale-free characteristics, where the degree distribution fits the power law, and the vertically equivalent structure is clear. We also present that the performance of firms are continuously affected by the degree centrality of firms in this network for the last 10 years.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.709-717
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• 2014

The objective of this study is to analyze the degree of correspondences among corners found in building facade imagery when the projective transformation parameters are applied to. Additionally, an appropriate corner detection operator is determined through experiments. Modeling of the shape of a building has been studied in numerous approaches using various type of data such as aerial imagery, aerial lidar scanner imagery, terrestrial imagery, and terrestrial lidar imagery. This study compared the Harris operator with FAST operator and found that the Harris operator is superior in extracting major corner points. After extracting corners using the Harris operator and assessing the degree of correspondence among corners in difference images, real corresponding corners were found to be located in the closest distance. The experiment of the projective transformation with varying corners shows that more corner control points with a good distribution enhances the accuracy of the correspondences.

• Archives of Plastic Surgery
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• v.39 no.2
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• pp.143-149
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• 2012

Background : Axillary osmidrosis is characterized by an unpleasant odor, profuse sweating, and in some instances, staining of clothes that may socially and psychologically impair affected individuals. Various types of surgical procedures have been developed for the treatment of axillary osmidrosis. This study was undertaken to evaluate the effectiveness of subcutaneous pulsed neodymium: yttrium-aluminum-garnet (Nd-YAG) laser treatment for the treatment of axillary osmidrosis. Methods : Twenty-nine patients with axillary osmidrosis were included in this study. Patients were categorized according to the results of an axillary malodor grading system, and a subcutaneous pulsed Nd-YAG laser was applied to all patients. The treatment area for the appropriate distribution of laser energy was determined using the iodine starch test (Minor's test) against a grid pattern composed of $2{\times}2cm$ squares. The endpoint of exposure was 300 to 500 J for each grid, depending on the preoperative evaluation results. The results were evaluated by measurement of axillary malodor both pre- and postoperatively using the grading system and iodine starch test. Results : The average follow-up period was 12.8 months. Nineteen patients had a fair-to-good result and ten patients had poor results. The postoperative Minor's test demonstrated that there were remarkable improvements for patients with mild to moderate symptoms. Complications including superficial second degree burns (n=3) were treated in a conservative manner. A deep second degree burn (n=1) was treated by a surgical procedure. Conclusions : Subcutaneous pulsed Nd-YAG laser has many advantages and is an effective noninvasive treatment for mild to moderate axillary osmidrosis.

• Journal of the Korean Society for information Management
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• v.28 no.4
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• pp.65-83
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• 2011

In this study, Network Text Analysis was performed on 1,752 articles which had been published in recent 7 years and drew the subject concept distribution and their relations in Library and Information Science research areas. Furthermore, for analyzing more recent trends and changing aspects, this study performed secondary analysis based on 482 articles published in recent 2 years. Results show that "public library", and "academic library" concepts were most frequently studied in the field and "evaluation", "education", and "web" concepts showed the highest-degree centrality during the recent 7 years. In the result of recent two years analysis, "web", and "classification" concepts showed high frequency and "user", and "public library" showed an improvement in high degree centrality.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.606-611
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• 2013

In this study, the regional states of 7 items are analyzed, the regional risks are calculated by using normalized data & analysis hierarchy process to set regional oil recovery capacity. Area on-water oil recovery capacity, $7,500k{\ell}$, is separated and regional on-water oil recovery capacity is determined, based on calculated regional degree of risk. Excessive current oil recovery capacities, setting in Incheon, Gunsan, Mokpo, Busan region, are as a result distributed to the other regions in each area. In case of central region, Daesan is increased as much as $1,475k{\ell}$, Yeosu is increased as much as $375k{\ell}$, Ulsan is increased as much as $475k{\ell}$. The regional on-water oil recovery capacity, considering both the cause of accident aspects and marine environmental & economic aspects, is estimated as more balanced distribution model, compared to current standard of on-water oil recovery capacity.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1443-1459
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• 2019

Polyglycerol fatty acid ester nonionic surfactants have been used for a long time in foods and have been suggested as an alternative to the safety problems of PEG based nonionic surfactants. The polyglycerol fatty acid ester surfactants are synthesized by combining a hydrophilic polyglycerin and a lipophilic fatty acid. The hydrophilic polyglycerin is polymerized using glycerin, glycidol, epichlorohydrin, etc. The main issues of the polyglycerol polymerization reaction are to increase the content of the polyglycerol in the form of linear rather than branched or cyclic forms and to narrow the distribution of the degree of polymerization. The method of binding a lipophilic fatty acid group to a hydrophilic polyglycerin includes chemical synthesis such as esterification reaction and enzyme synthesis using lipase enzyme. The main issues of polyglycerin fatty acid ester synthesis are to increase the yield and to control the degree of esterification while reducing side reactions.

• Carbon letters
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• v.25
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• pp.95-102
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• 2018

We examined the pressure effects on petroleum pitch synthesis by using open and closed reaction systems. The pressure effects that occur during the pitch synthesis were investigated in three pressure systems: a closed system of high pressure and two open systems under either an atmosphere or vacuum. A thermal reaction in the closed system led to the high product yield of a pitch by suppressing the release of light components in pyrolysis fuel oil. Atmospheric treatment mainly enhanced the polymerization degree of the pitch via condensation and a polymerization reaction. Vacuum treatment results in a softening point increase due to the removal of components with low molecular weights. To utilize such characteristic effects of system pressure during pitch preparations, we proposed a method for synthesizing cost-competitive pitch precursors for carbon materials. The first step is to increase product yield by using a closed system; the second step is to increase the degree of polymerization toward the desired molecular distribution, followed by the use of vacuum treatment to adjust softening points. Thus, we obtained an experimental quinoline insolubles-free pitch of product yield over 45% with softening points of approximately $130^{\circ}C$. The proposed method shows the possibility to prepare cost-competitive pitch precursors for carbon materials by enhancing product yield and other properties.