• Proceedings of the Korean DIstribution Association Conference
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• 2006.08a
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• pp.47-68
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• 2006

This study aims to determine the association structure of the behavioral relationship variables, such as trust, commitment, cooperation, communication and coercive power, in the relationship between the buyers and suppliers of industrial parts. It also investigates the impact of the use of IT technologies on the relationships quality. Data was collected from 216 part suppliers of machinery, electronics and automobiles located in Incheon. Data supported all of the proposed hypotheses. First, it was confirmed that parts suppliers' trust in buyers leads to the commitment into relationships with buyers. Second, cooperation and communication showed a positive influence on parts suppliers' trust in buyers, and coercive power gave a negative influence on trust. Third, the use of IT technologies like Internet and E-Mail between parts suppliers and buyers was verified to have generally a positive influence on the quality of relationships. At the same time, cooperation and communication were confirmed to have a positive influence on each other, and cooperation and coercive power as well as communication and coercive power were confirmed to have negative influence on each other. This study is a pioneering attempt to examine the relationships between suppliers and buyers of industrial parts, and the influence IT technologies on the relationship quality. Also, the findings will be practically much helpful to find how to reinforce the relationships between parts suppliers and buyers.

• The Korean Journal of Quaternary Research
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• v.2 no.1
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• pp.25-50
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• 1988

The survival of rich evidence of palaeolithic occupation found in the Imjin-Hant'an River basin was possible due to many fortuitous geological conditions provided there. Formation of the basalt plain in a narrow valley system which developed during the late Mesozoic insured the appearance of a basin of sedimentation in which archaeological sites would be preserved with relatively minor post-depositional disturbance. Geomagnetic and K-Ar dating indicates that lava flows occurred during the Brunes Normal Epoch. During and after the process of basin sedimentation, erosion of the plain was confined to the major channel of the present river system which developed along the structural joints formed by the lava flow. Due to characteristic columnar structure and platy cleavage of the basalt bedrock, erosion of the basalt bedrock occurred mainly in vertical direction, developing deep but narrow entrenched valleys cut into the bedrock. Consequently, the large portion of the site area remained intact. Cultural deposits formed on top of the basalt plain were left unmodified by later fluvial disturbances due to changes in the Hant'an River base-level, since they were formed about 20 to 40m above the modern floodplain. Sedimentological evidence of cultural deposits and palynological analysis of lacustrine bed formed in the tributary basin of the Hant'an River indicate that hominid occupation occurred in this basin under rapidly deteriorating climatic conditions. From three thermoluminescence dates, the timing of hominid occupation as represented by 'Acheulian-like' bifaces apparently occur sometime during 45,000 BP. Thus, deposition of cultural layers in this basin approximately coincides with the beginning of the second stadial of the final glacial, during which the Korean Peninsula must have had provided a sanctuary for prolonged human occupation.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.642-650
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• 2020

In general, the circulation path of the fluidized particles in a CFB (Circulating Fluidized Bed) boiler is such that the particles entrained from a combustor are collected by a cyclone and recirculated to the combustor via a sealpot which is one of non-mechanical valves. However, when a fluidized bed heat exchanger (FBHE) is installed to additionally absorb heat from the fluidized particles, some particles in the sealpot pass through the FBHE and then flow into the combustor. At this time, in the FBHE operated in the bubbling fluidization regime, if the heat flow is not evenly distributed by poor mixing of the hot particles (800~950 ℃) flowing in from the sealpot, the heat exchanger tubes would be locally heated and then damaged, and the agglomeration of particles could also occur by formation of hot spot. This may affect the stable operation of the circulating fluidized bed. In this study, the unevenness of heat flow arising from structural problems of the FBHE of the domestic D-CFB boiler was found through the operating data analysis and the CPFD (Computational Particle Fluid Dynamics) simulation using Barracuda VR. Actually, the temperature of the heat exchanger tubes in the FBHE showed the closest correlation with the change in particle temperature of the sealpot. It was also found that the non-uniformity of the heat flow was caused by channeling of hot particles flowing in from the sealpot. However, it was difficult to eliminate the non-uniformity even though the fluidizing velocity of the FBHE was increased enough to fluidize hot particles vigorously. When the premixing zone for hot particles flowing in from the sealpot is installed and when the structure is changed through the symmetrization of the FBHE discharge line for particles reflowing into the combustor, the particle mixing and the uniformity of heat flow were found to be increased considerably. Therefore, it could be suggested that the structural modification of the FBHE, related to premixing and symmetric flow of hot particles, is an alternative to reduce the non-uniformity of the heat flow and to minimize the poor particle mixing.

• Resources Recycling
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• v.12 no.6
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• pp.38-46
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• 2003

In this study, nano-sized Ni-ferrite and $Fe_2$$O_3$＋NiO powder was fabricated by spray pyrolysis process in the condition of 1kg/$\textrm{cm}^2$ air pressure using the Fe-Ni complex waste acid solution generated during the manufacturing process of shadow mask. The average particle size of the produced powder was below 100 nm. The effects of the reaction temperature, the concentration of raw material solution and the nozzle tip size on the properties of powder were studied. As the reaction temperature increased from $800 ^{\circ}C$ to $1100^{\circ}C$, the average particle size of the powder increased from 40 nm to 100 nm, the structure of the powder gradually became solid, yet the distribution of the particle size appeared more irregular. Along with the increase of the reaction temperature, the fraction of the Ni-ferrite phase were also on the rise, and the surface area of the powder was greatly reduced. As the concentration of Fe in solution increased from 20g/l to 200g/l, the average particle size of the powder gradually increased from 30 nm to 60 nm, while the distribution of the particle size appeared more irregular. Along with the increase of the concentration of solution, tie fraction of the Ni-ferrite phase was on the rise, and the surface area of the powder was greatly reduced. Along with the increase of the nozzle tip size, the distribution of the particle size appeared more irregular, yet the average particle size of the powder showed no significant change. As the nozzle tip size increased from 1 mm to 2 mm, the fraction of the Ni-ferrite phase showed no significant change, while the surface area of the powder slightly reduced. As the nozzle tip size increased to 3 mm and 5 mm, the fraction of the Ni-ferrite phase gradually reduced, and the surface area of the powder slightly increased.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.1-8
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• 1973

This study examined the morphological, physical and chemical characteristics of the Yesan and the Songjeong series derived from residuum of the granite developed on gently sloping to rolling relief in Honam reclamable land Area. The results of this study are summarized as follows. 1. The morphological characteristics. In the Yesan series, the surface soils(Ap horizons) are brown to dark brown sandy loam. The subsoils(B horizons) are yellowish red to red sandy clay loam to sandy loam and the soil profile development is weak. The Songjeong series, the surface soils (Ap horizons) are washed by erosion, so the subsoils are revealed on the surface, and these are dark red silty clay loam. The subsoils (B horizons) are red silty clay loam and thin clay cutans are formed on the ped faces of the structure. The substrata of two soil series are deeply weathered granitic saprolite. 2. The physical and chemical characteristics. The distribution of clay content tends to increase from surfaces to subsoils with depth gradually. On the Yesan series, the content of clay is less than 18%, soil pH (6.0 in the surface-soil, 4.5-5.0 in the subsoil), the content of organic matter (1.8% in the surface soil, 0.1~0.4% in the subsoil), available phosphate (40 ppm), the cation exchange capacity(4~8 me/100 gr) are very low, and the base saturation (57.8% in the surface soil, 46.3% in the subsoil) is moderate. On the Songjeong series, the content of clay is 30~40%, pH (5.7-6.0), the content of in organic matter (1.25% in the surface soil, 0.1~0.4% in the subsoil), available phosphate(4 ppm), the cation exchange capacity(6.2 me/100 gr in the surface soil, 2~6 me/100gr in the subsoil) are very low, and the base saturation(28.1% in the surfacesoil, 16~23% in the subsoil) is also low. 3. The Yesan and Songjeong series are for med under a temperate humid climate, and classified as Red Yellow Soils in the old classification system. According to U.S.D.A. 7th approximation the former belongs to Typic Dystrochrepts in Inceptisols, and the latter, Typic Hapludults in Ultisols.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.52-60
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• 2016

The biological activity of polysaccharide is greatly influenced by polysaccharide structure and molecular distribution. Here, we developed a rapid and convenient isolation method for fractionating polysaccharides with different characteristics and optimized it using a polysaccharide mixture from Korean persimmon leaves. A crude polysaccharide mixture, persimmon leaves-enzyme (PLE) fraction, was isolated from persimmon leaves digested with pectinase and ethanol precipitation. The PLE fraction was further fractionated with a serially diluted ethanol solution (ethanol : deionized water=4:1, 2:1, 1.5:1, 1:1, and 0.5:1) to produce 10 subfractions (five precipitate fractions labeled from PLE-4 to PLE-0.5 and five supernatant fractions labeled from PLE-4S to PLE-0.5S). HPLC analysis indicated that PLE-4 and -2 consisted of diverse polysaccharides, whereas PLE-1.5, -1, and -0.5 contained high molecular weight (MW) polysaccharides. The fractions from PLE-4 to PLE-1 were mostly composed of 13 different characteristic sugars in rhamnogalacturonan (RG) I and II, and the sugars contained an arabino-${\beta}$-3,6-galactan moiety. However, PLE-0.5 did not contain RG-II or ${\beta}$-arabino-3,6-galactan. Treatment of macrophages with fractions PLE-1.5S and PLE-1S led to a $10{\mu}g/mL$ increase in interleukin (IL)-6 production, whereas treatment with PLE-4S and PLE-2S fractions composed of low MW polysaccharides resulted in reduced levels of IL-6. These results indicate that this isolation method may be useful for the rapid and convenient fractionation of bioactive RGs from polysaccharide mixtures with various properties.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.1-7
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• 2004

Roads, like bikeways, parkways and walks, are to be just capable of supporting light traffic and traveling public, but they are required to be human friendly and environmental-oriented. Lately soil-solidifier mixture, a kind of soil-cement, has developed and has been applied to the recycling and environment-oriented pavement as the surfacing material. Soil-solidifier pavement structure has been designed by only experience. To design this pavement mechanically, it is necessary to find out basic engineering properties of soil-solidifier mixture. This study focuses on finding out mechanical characteristics of the mixture according to mixture proportions and aging. Test molds with various mixture proportions are made, and then unconfined strength tests are performed for test molds with aging of the mixture. As the result of this study, it is found that the strength of the mixture increases with amount of cement and that maximum strength is achieved at 6%$\sim$8% of the ratio of solidifier and water. The strength increase rapidly until 14 days, after then slowly. After 28 days the strength of the mixture approaches to the constant value. The heat of hydration during curing of the mixture is measured no significantly. It also shows that temperature characteristics of the mixture is similar to that of soil. Since this mixture is mixed with soil and is able to improve engineering problems in pavement due to temperature, this mixture is expected to use effectively in the environment-oriented pavement for light traffic.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.490-499
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• 2008

Statement of problem: Bioactive materials must have the ability to spontaneously form a bone like apatite layer on their surface and induce direct biochemical bonding to bone. A simple chemical treatment via alkali and heat has been revealed to induce bioactivity in titanium. Purpose: The purpose of this study was to evaluate the surface characteristics and stability of alkali and heat treated implants. Material and methods: Specimens were divided into three groups; group 1 was the control group with machined surface implants, groups 2 and 3 were treated with alkali solutions and heat treated in the atmosphere and vacuum conditions respectively. The surface characteristics were observed with FESEM, XPS, TF-XRD and AFM. Stability was evaluated with the resonance frequency analysis, periotest and removal torque values. One-way ANOVA and Duncan test were used for statistical analysis. Results: 1. Groups treated with alkali and heat showed similar characteristics. Groups 2 and 3 showed high compositions of Na ions on the surface with sub-micron sized pores compared to group 1. Group 2 showed mixed compositions of anatase and rutile with superior contents of rutile. 2. Resonance frequency analysis : The ISQ of group 2 showed significantly higher values than that of groups 1 and 3 at 12 weeks. The ISQ of groups 1 and 2 showed significant increase after 4 weeks, and the ISQ of group 3 increased significantly after 2 and 4 weeks respectively (P < .05). 3. Periotest: The PTV of groups 1 and 2 showed significant decrease after 4 weeks, and the PTV of group 3 showed significant decrease after 2 and 4 weeks respectively (P < .05). 4. Removal torque analysis: The removal torque value of group 2 was significantly higher than those of groups 1 and 3 at 2, 4 and 8 weeks. The removal torque values of groups 1 and 3 showed increase at 4 and 12 weeks, but the removal torque value of group 2 showed increase after 4 weeks (P < .05). Conclusion: An oxide layer with appropriate crystal structure and amorphous sodium titanate layer can be obtained on titanium implants through alkali and heat treatment in the atmosphere, and even alkali and heat treatment in vacuum conditions, provided a bioactive surface containing sodium. These surface layers can be considered to be effective for enhancement of osseointegration and reduction of healing period for implant treatment.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.440-447
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• 2020

The demand for large-scale horticultural complexes utilizing reclaimed lands is increasing, and one of the pending issues for the construction of large-scale facilities is to establish foundation design criteria. In this paper, we tried to review previous studies on the method of reinforcing the foundation of soft ground. Target construction methods are spiral piles, wood piles, crushed stone piles and PF (point foundation) method. In order to evaluate the performance according to the basic construction method, pull-out resistance, bearing capacity, and settlement amount were measured. At the same diameter, pull-out resistance increased with increasing penetration depth. Simplified comparison is difficult due to the difference in reinforcement method, diameter, and penetration depth, but it showed high bearing capacity in the order of crushed stone pile, PF method, and wood pile foundation. In the case of wood piles, the increase in uplift resistance was different depending on the slenderness ratio. Wood, crushed stone pile and PF construction methods, which are foundation reinforcement works with a bearing capacity of 105 kN/㎡ to 826 kN/㎡, are considered sufficient methods to be applied to the greenhouse foundation. There was a limitation in grasping the consistent trend of each foundation reinforcement method through existing studies. If these data are supplemented through additional empirical tests, it is judged that a basic design guideline that can satisfy the structure and economic efficiency of the greenhouse can be presented.

• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.123-133
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• 2007

This study analyzed whether a transit network with hierarchy is efficient or not, and if transit network hierarchy has cost efficiency, then which condition guarantees the efficiency of the transit network hierarchy. The authors modeled the total cost of the transit network and suggested the conditions in which the transit network hierarchy has cost efficiency through comparing the cost of the transit network with and without hierarchy. The efficiency of transit network hierarchy is guaranteed when the travel cost savings induced by using a higher hierarchy transit network is larger than the increasing non-travel cost, which is the sum of access cost, waiting cost, and operating cost, induced by the introduction of a higher hierarchy transit network. This result is consistent with common sense and with the concept of cost and benefit analysis. If a passenger traveling within the area divided by a higher hierarchy transit network uses only a lower hierarchy transit network and the passenger traveling out of the area divided by the higher hierarchy transit network uses both lower and higher hierarchy transit networks, the travel demand using the higher hierarchy transit network is inversely proportional to the square of the line spacing. This means that the transit network becomes more efficient and small increases of travel demand guarantee the efficiency of the transit network hierarchy as the connectivity of the network becomes higher. This result shows that transit networks have economies of aggregation. This study is the first analytical research on transit network hierarchy and is expected to be a basis for numerical research. However, numerical research should complement this study, since analytical research has some limitations for considering a real network.