• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.43-50
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• 2007

Liposomes having particle size from several tens to hundreds nanometers are efficient carriers for injectable drug delivery. Enhancement of liposome stability in bloodstream has been studied because of its relatively short circulation time and fast clearance from human body by reticuloendothelial system (RES) in blood vessel. In this study, new disaccharide-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) derivatives in which lactose or sucrose as the disaccharide molecule was conjugated covalently to DSPE were synthesized. Liposomes of which surface had disaccharide molecules were prepared by incorporating the disaccharide-DSPE into liposomes as one of their lipid components. Particle size of the prepared liposomes was approximately 100 nm. The liposomes of which surface were modified with the disaccharide-DSPE showed -25 mV of zeta potential value due to the presence of hydroxyl groups on their surface, while the unmodified control liposomes showed -10 mV of zeta potential value. Loading efficiency of model drug, doxorubicin, into liposomes was about 90%. Stability of the disaccharide-modified liposomes in vitro was evaluated by monitoring the amount of protein adsorption and particle size of the liposomes in serum. Disaccharide-modified liposomes were more stable in serum than unmodified control liposomes or polyethyleneglycol (PEG)-modified liposomes due to less adsorption of serum protein and hence less increase of their particle size. The liposomes of which surface was modified with disaccharide-DSPE conjugate can be used as long-circulating carriers for drugs having high toxicity or short half-life time due to their enhanced stability in blood circulatory system.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.434-449
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• 2019

In this study, we develop a new cross-shore sediment module which takes the effect of infra-gravity waves of bound mode, and boundary layer streaming on the sediment transport into account besides the well-known asymmetry and under-tow. In doing so, the effect of individual random waves occurring during the unit observation period of 1 hr on sediment transport is also fully taken into account. To demonstrate how the individual random waves would affect the sediment transport, we numerically simulate the non-linear shoaling process of random wavers over the beach of uniform slope. Numerical results show that with the consistent frequency Boussinesq Eq. the application of which is lately extended to surf zone, we could simulate the saw-tooth profile observed without exception over the surf zone, infra-gravity waves of bound mode, and boundary-layer streaming accurately enough. It is also shown that when yearly highest random waves are modeled by the equivalent nonlinear uniform waves, the maximum cross-shore transport rate well exceeds the one where the randomness is fully taken into account as much as three times. Besides, in order to optimize the free parameter K involved in the long-shore sediment module, we carry out the numerical simulation to trace the yearly shoreline change of Mang-Bang beach from 2017.4.26 to 2018.4.20 as well, and proceeds to optimize the K by comparing the traced shoreline change with the measured one. Numerical results show that the optimized K for Mang-Bang beach would be 0.17. With K = 0.17, via yearly grand circulation process comprising severe erosion by consecutively occurring yearly highest waves at the end of October, and gradual recovery over the winter and spring by swell, the advance of shore-line at the northern and southern ends of Mang-Bang beach by 18 m, and the retreat of shore-line by 2.4 m at the middle of Mang-Bang beach can be successfully duplicated in the numerical simulation.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.547-561
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• 2005

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a ffw previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about $28\%$ of the shallow groundwaters exceeded the Bangladesh drinking water standard, $50{\mu}g/L$, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of $SO_4^{2-}$ and $NO_3^-$, and high contents of dissolved organic carbon (DOC) and $NH_4^+$ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciatiion during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about $1\%$ of grounwaters have concentrations higher than $10{\mu}g/:L.$ However, it was revealed that $19.3\%$ of mineral waters, and $7\%$ of tube-well waters from Nonsan and Geumsan areas contained As concentrations above $10{\mu}g/:L.$. Also, percentages exceeding this value during detailed groundwater quality surveys were $36\%\;and\;22\%$ from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 1998.10a
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• pp.2-4
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• 1998

Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.535-543
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• 2008

Purpose: The objective of this study was to compare the bonding characteristics of a new self-adhesive resin cement to dentin, which does not require bonding and conditioning procedure of the tooth surface, and conventional resin cement. The effect of phosphoric acid etching prior to application of self-adhesive resin cement on the shear bond strength was also evaluated. Material and methods: Fortyfive non-carious human adult molars extracted within 6 months were embedded in chemically cured acrylic resin. The teeth were ground with a series of SiC-papers ending with 800 grit until the flat dentin surfaces of the teeth were exposed. The teeth were randomly divided into 3 experimental groups. In group 1, self-adhesive resin cement, RelyX Unicem (3M ESPE, Seefeld, Germany) was bonded without any conditioning of teeth. In group 2, RelyX Unicem was bonded to teeth after phosphoric acid etching. For group 3, Syntac Primer (Ivoclar Vivadent AG, Schaan, Liechtenstein) was applied to the teeth before Syntac adhesive (Ivoclar Vivadent AG, Schaan, Liechtenstein) and Helibond (Ivoclar Vivadent AG, Schaan, Liechtenstein) followed by conventional resin cement, Variolink II (Ivoclar Vivadent AG, Schaan, Liechtenstein). To make a shear bond strength test model, a plastic tuble (3 mm diameter, 3 mm height) was applied to the dentin surfaces at a right angle and filled it with respective resin cement, and light-polymerized for 40 seconds. All the specimens were stored in distilled water at $37^{\circ}C$ for 24 hours before test. Universal Testing Machine (Z020, Zwick, Ulm, Germany) at a cross head speed of 1 mm/min was used to evaluate the shear bond strength. The failure sites were inspected under a magnifier and Scanning Electron Microscope. The data was analyzed with One way ANOVA and Scheffe test at ${\alpha}$= 0.05. Results: (1) The shear bond strengths to dentin of RelyX Unicem was not significantly different from those of Variolink II/Syntac. (2) Phosphoric acid etching lowered the shear bond strength of RelyX Unicem significantly. (3) Most of RelyX Unicem and Variolink II showed mixed fractures, while all the specimens of RelyX Unicem with phosphoric acid etching demonstrated adhesive failure between dentin and resin cement. Conclusion: Shear bond strength to dentin of self-adhesive resin cement is not significantly different from conventional resin cement, and phosphoric acid etching decrease the shear bond strength to dentin of self-adhesive resin cement.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.387-394
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• 2012

The study was conducted to develop an effective forest resources use models for an alternate use of abandoned quarry by an attitude survey. According to the result of survey, a pessimistic view due to dust, noise pollution, and forest damage was 5% higher than an affirmative view by economic benefits from the development of quarry. The 42% of the respondents preferred the alternate use of abandoned quarry and the 25% of the respondents wanted an art and cultural space. The optimum size of alternate use was 5-10 ha (43%) with the requirement of nearby residents (32%). According to the SWOT analysis for abandoned quarry, the strength factors were an effective use of land, the content development of modern industrial inheritance + cultural and art fusion, attraction for nearby city and visitors, a harmony of beauty landscape and clean environment, and a sustainable increase of domestic and foreign visitors with the 5-day-work week. The opportunity factors were the improvement of traffic networks through KTX and local highway, the creation of the new growth engines with the establishment of artistic creation belts, the providing of unique cultural and art space through grafting of tour and education, the creation of local income through stone processed goods, and the vitalization of local development through eco-city. The weakness factors were a psychological remoteness and backwardness, and the weakness of staying tour infra. The threat factors were a poor financial support for sustainable development in nearby quarry and a modify of legal and institutional system for the alternated use of abandoned quarry. The developed restoration models for the alternate use in abandoned quarry are classified to a sculpture park, a waterfall and lake park, a rock-climbing, a sports park + forest park, a native botanical garden, a culture and art park, a complex park, a water storage site, a water storage site to extinguish forest fire, a geriatric hospital, an agricultural facility, and a school site types etc. The results suggest that the alternate use in the abandoned soil and stone quarry is needed to establish facility use models with consideration of user's preference.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.5
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• pp.13-35
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• 2020

Startup accelerators are a new type of investors providing a certain amount of shares for imparting education, mentoring, networking, and providing space and seed money that can directly resolve the difficulties faced by nascent entrepreneurs (Clarysse, 2016). Startup accelerators have expanded worldwide as their influence over the startup ecosystem has increasingly been established (Pauwels et al., 2016; Cohen & Hochberg, 2014). This study was conducted to derive investment determinants of startup accelerators that are emerging as major investment players around the world. To this end, the accelerator-type determinants of investment were derived. As previous research on this topic is nonexistent, this process involved qualitative meta-synthesis, literature reviews, observation, and in-depth interviews. First, more than 30 research papers were examined for the determinants of investment for firms at an early stage of their foundation, and the categories and determinants of investment in the relevant studies were comparatively analyzed using qualitative meta-synthesis. Further, related data were investigated to identify the characteristics of accelerators, and the startup evaluation process of US accelerators was studied. The more than 100 questions raised during this process were coded to examine the determinants of investment that accelerators considered important. In-depth interviews were conducted with four US accelerators to identify the characteristics of accelerators and key determinants of investment. Ultimately, 5 categories of accelerator-type determinants of investment and 26 subordinate determinants of investment were derived. The results were verified and supplemented by consulting with seven accelerators in Korea. The results were confirmed after pilot tests and verification by seven domestic accelerators. After confirming the accelerator-type determinants, the reliability of them was verified by examining the importance and priority of each category through the quantitative survey of Korean accelerators. The research that elicited the accelerator-type investment determinants is the first research and is expected to be a major reference to the progress of subsequent studies. This research that systematically derived the investment determinants of the accelerator is expected to make major contributions to the progress of follow-up studies, the process of selecting startups, and the investment decision-making process of the accelerators.

• Proceedings of the CALSEC Conference
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• 2002.01a
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• pp.86-106
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• 2002

Informatization is a process that corporation's external environmental factors and internal environmental factors influence as complex. is a phenomenon that appears via this process. To evaluate that informatization was propeled well or informatization level is high can be dangerous work extremely by only once-over-lightly some factors, organization information ability is superior or infrastructure is constructed well. Therefore, an evaluation for industrial information systems that consider corporation's external environment and internal environment configurationally and objective estimation through this is required in national dimension. This research sorted types of business using types of business classification of 2001 EIII(Evaluation Indices of Industrial Informatization) laying stress on corporation's product and product production process for reflecting various industrial classification. And we are dividing whole our country corporations by manufacture industry, the construction industry, distribution industry, service industry, banking industry 5 types of business. To see such classed types industry classification from consistent viewpoint, we saw them within new framework, purchase, operation, physical distribution, marketing and sale. service etc. laying stress on primary businesses except support businesses of planning, financial management etc. To draw special quality of business center from primary business of each types of business, we draw industry classification Key Capability that centers when plans corporation's corporate strategy and information strategy. And we deducted industrial classification key production business connected with industry classification Key Capability. After drawing an evaluation items for industrial information systems in informatization analysis viewpoint laying stress on drawn businesses. Finally we did Case Study by making out an evaluation for industrial information systems questionnaire that considers special quality of manufacturing industry. Through EIII that consider the industrial classification, we could know that it explains the corporation's purchase, production, distribution in general and detail.

• Journal of Periodontal and Implant Science
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• v.27 no.4
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• pp.867-882
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• 1997

Safflower(Carthamus tinctorius $Linn\acute{e}$ has been traditionally used for the treatment of blood stasis, and Dipsasi Radix has been used as a drug for fracture in Chinese medicine. The purpose of present study was to examine the biologic effects of safflower extract and Disasi radix extracts on the periodontal. ligament cells and osteoblastic cells and on the wound healing of rat calvarial defect. The ethanolic extract of safflower blossom, safflower seed and Dipsasi Radix(125, 250, and 500 ${\mu}g/ml$) were prepared as test group, and PDGF-BB(lOng/ml) and unsafonifiable fraction of Zea Mays L.(125, 250, and 500 ${\mu}g/ml$) were employed as positive control. The effects of each agents on the growth and survival, ALPase activity, expression of PDGF-BB receptor, chemotactic response of PDL cell and ATCC human osteosarcoma MG63 cells in vitro were examined. The tissue regenerative effect of each extracts was evaluated by histomorphometric measuring of newly formed bone on the 8mm defect in rat calvaria after oral administration of 3 different dosages groups : 0.02, 0.1 and 0.35g/kg, per day. It was also employed the same dosages of unsaponifiable fraction of Zea Mays L. as positive controls. Safflower blossom extract, safflower seed extract, and Dipsasi Radix extract stimulate the cellular activity of MG63 cells in concentration range of $125-500{\mu}g/ml$, and safflower bolssom extract and safflower seed extract stimulate also the cellular activity of periodontal ligament cells in concentration range of $250-500{\mu}g/ml$. In activity of ALPase, $250-500{\mu}g/ml$ of safflower blossom extracts showed significant stimulating effects on MG63 cells, and the same concentration range of safflower seed extracts showed significant effect on periodontal ligament cells. In the recovery on PDGF-BB receptor expression which was depressed by $IL-1{\beta}$, $125-250{\mu}g/ml$ of safflower blossom extracts and $250-500{\mu}g/ml$ of safflower seed extracts showed significant increasing effect on MG63 cells, and $500{\mu}g/ml$ of safflower blossom extract and $250-500{\mu}g/ml$ of safflower seed extracts showed significant effect on periodontal ligament cells. In chemotactic response, among all tested group, safflower seed extracts only were chemotactic to MG63 cells and periodontal ligament cells in concentration range of $125-500{\mu}g/ml$. Also in the view of bone regeneration in rat calvarial defect model, the only group that was orally administrated 0.35g/kg, day of safflower seed extract showed significant new bone formation. These results suggested that safflower extracts might have a potential possibilities as an useful drug for adjunct to treatment for regeneration of periodontal defect.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.6
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• pp.1-11
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• 2009

This study focuses on Abstract Types in Contemporary Landscape Design. The formation and artistry of contemporary landscape design reveals many areas which Previously have not been able to be expressed in scenic landscape thanks to the deviation of the genre in contemporary landscape and the hybridization that has occurred among architecture, landscape and art genres. The focus of this study is basic research concerning "the abstract", which is used as a creative artistic theory in a variety of art fields such as landscape, architecture and painting. Through a theoretical establishment of "the abstract", its process of change, and the discovery of its contemporary principles, the relationship between each art field in landscapes and the formation of the abstract, abstract language, and abstract properties have been studied. The use of the abstract in contemporary landscape design can be classified in three ways: Inductive abstract representing conceptual transcendental symbols not logically but rather through intuition and transcendental cognition to display the inner expressions, ideas and minds of the artists. Second, a deductive abstract represents an expansive, logical model for the simplification of objects, distortion, exaggeration based on knowledge and logical reasoning about objective fact based on traditional realism. The complexity of the abstract is a concept that is bound to both the deductive & inductive abstract. As a major trend, the concept of "The abstract" in contemporary landscape has been putting forth ever-deeper roots. New trends like abstract works and landscape architecture reflecting the artist's inner expression, in particular, will provide fertile soil for landscape in the future. Further research about the concept of "the abstract" will also be necessary in the time to come.