• Ocean and Polar Research
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• v.42 no.3
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• pp.211-223
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• 2020

With the increasing demand for improved marine environments and safety, greater ability to minimize damages to coastal areas from harmful organisms, ship accidents, oil spills, etc. is required. In this regard, an accurate assessment and understanding of current systems is a crucial step to improve forecasting ability. In this study, we examine spatial and temporal characteristics of current systems in the adjacent seas of Jeju Island using a high-resolution regional ocean circulation model. Our model successfully captures the features of tides and tidal currents observed around Jeju Island. The tide form number calculated from the model result ranges between 0.3 and 0.45 in the adjacent seas of Jeju Island, indicating that the dominant type of tides is a combination of diurnal and semidiurnal, but predominantly semidiurnal. The spatial pattern of tidal current ellipses show that the tidal currents oscillate in a northwest-southeast direction and the rotating direction is clockwise in the adjacent seas of Jeju Island and counterclockwise in the Jeju Strait. Compared to the mean kinetic energy, the contribution of tidal current energy prevails the most parts of the region, but largely decreases in the eastern seas of Jeju Island where the Tsushima Warm Current is dominant. In addition, a Lagrangian particle-tracking experiment conducted suggests that particle trajectories in tidal currents flowing along the coast may differ substantially from the mean current direction. Thus, improving our understanding of tidal currents is essential to forecast the transport of marine pollution and harmful organisms in the adjacent seas of Jeju Island.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.26-39
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• 2016

Korea's main manufacturing industries, which have led its economy for the past three decades, are faced with a serious downturn and loss of competitive advantages due to the current economic depression, China's rise, and the drop of oil prices. Korean business firms must adopt the paradigm shift in their value strategies, along with a government-led industrial restructuring in order to gain sustainable competitive advantages. Business firms allocate their limited resources between value creation and value appropriation, however, what effect does strategic emphasis on value creation versus value appropriation have on a business firm's financial performance? This paper empirically addresses this issue by examining the effect of shifts in strategic emphasis on stock return. Furthermore, this study examines appropriate choices of strategic emphasis to gain differential financial performance. The data set used in this regression analysis comes from the KISLINE database of NICE Information Service. The variables that form the basis of this analysis are stock return, ROA, and Strategic Emphasis [(advertising expenditures-R&D expenditures)/assets]. The interactive effect with situational factors regarding the firm and the type of technological environment in which the firm is operating was also analyzed. Our results show that investors acknowledge a shift of strategic emphasis as a sign of stock valuation. In comparison to US, Korean business firms have weak value creation capabilities in high-technology industries, and weak value appropriation capabilities in low-technology industries. This proves Korean firms are fast followers in the global market. Our findings suggest that Korean firms have to adopt a balanced value strategy, nurturing value creation and developing value appropriation for overcoming the current economic downturn and becoming a first mover in the dawn of "Industry 4.0."

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.6
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• pp.603-612
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• 2016

The objective of this study was to estimate the emission characteristics for PM, $PM_{10}$, and $PM_{2.5}$ in the various stationary sources. The particulate matters collected in the various stationary sources such as power plants (Coal and B-C oil), incinerators(municipal and industrial waste), and glass furnaces. The PM and $PM_{10}$, PM and $PM_{2.5}$, $PM_{10}$ and $PM_{2.5}$ samples were collected using the cyclone type $PM_{10}$, $PM_{2.5}$ samplers and 30 species(19 inorganic species, 9 ionic species, OC and EC) were analyzed by ICP, IC, and TOR/IMPROVE methods. The mass concentrations of PM, $PM_{10}$, $PM_{2.5}$ from nine stationary sources ranged $0.63{\sim}9.58mg/Sm^3$, $0.26{\sim}7.47mg/Sm^3$ and $0.13{\sim}6.34mg/Sm^3$, respectively. The level of $PM_{10}$, $PM_{2.5}$ portion in PM calculated 0.63~0.99, 0.38~0.94, respectively. In the case of emission trend for species, power plant showed high concentrations for Al, Mg, Na, Si, V and $SO_4{^{2-}}$, respectively. Also, Ca, Fe, K, Si, $Cl^-$, and $K^+$ showed high in incinerator. In the case of glass furnace, Na, Pb, K, Si, $Na^+$ and $SO_4{^{2-}}$ represented high concentrations. Power plant showed higher EC/OC concentrations than other sampling sites. These results suggest the possible role for complement establishment process of emission inventory and emission management for PM.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1265-1273
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• 2015

A coal handling machine is a type of equipment used for loading coal, the main material in a steam power plant, along a conveyer belt from a ship, and is placed after the driving chain bucket. However, studies on the boom hoisting cylinder, which is a hydraulic system used to control the angle of the boom based on loading location, indicate that domestic models are insufficient, and are thereby often substituted with a foreign product. In this study, a technique for analyzing the contact pressure in a thick-walled cylinder was established by comparing the contact pressure, which is calculated theoretically based on the results obtained from FEM simulation, and by checking whether the working oil is leaking from the boom hoisting cylinder using a v-seal. In addition, the driving motion was simulated according to the strokes of the cylinder, and the structural stability was verified under the maximum output conditions.

• Archives of Reconstructive Microsurgery
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• v.24 no.2
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• pp.75-78
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• 2015

High-pressure (HP) injection injury to the upper extremity often causes a very serious clinical problem, leading to poor outcomes, including amputation, so that a true surgical emergency is required. The outcomes can be improved with emergent wide surgical debridement. However the diagnosis of these injuries is often delayed due to underestimated evaluation at first appearance and lack of common knowledge of the seriousness of this injury. The type and pressure of the infecting material is an important factor in prognosis and organic solvents infected pressure injury can cause poor outcome and increased amputation rate. In this case, we report on reconstruction of HP oil-based paint injection injuries of the finger using T-shaped pedicles and multiple venous anastomoses. In this concept, arterial flow can be maintained by the reverse flow of distal anastomosis when there is difficulty with the proximal anastomosis. And venous flow can be preserved by deep and superficial vein anastomosis. This concept has various advantages including preserving patency of the pedicle in chronic vasculopathy or trauma cases and maintaining the arterial flow by the reverse flow of distal anastomosis and can improve the free flap survival by a two vascular anastomosis system.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.683-691
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• 1993

All the activities and physical properties including surface tension, foaming power, foam stability, emulsifying power, dispersion effect, wettability and solubilization of sodium dodecyl polyoxyethylene ${\alpha}$-sulfo alkanoates aqueous solution were measured and critical micelle concentration was evaluated. Their cmc ebaluated by the surface tension method was $10^{-4}{\sim}10^{-5}mol/{\ell}$, and surface tension of the aqueous solution was decreased to 30~70dyne/cm. The experimental results for foaming power, foam stability, emulsifying power in benzene or soybean oil, dispersion effect in calcium carbonate, wettability and solubilization showed a good and efficient surface active properties, and then it would be expected that these products could be applied as O/W type emulsifier, dispersion agent.

• Polymer(Korea)
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• v.27 no.4
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• pp.370-376
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• 2003

Poly(DL-lactide-co-glycolide) nanoparticles were prepared by the modified spontaneous emulsification solvent diffusion method. Polymer solution was prepared by two water-soluble organic solvents, such as ethanol and acetone. Because of its biocompatible nature, PEG-PPG diblock copolymer was used as surfactant and stabilizer. The influence of several preparative variables on the nanoparticle formation, such as type and concentration of stabilizing agent, stirring methods, water/oil phase ratio and polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles, particle size and distribution were evaluated by the light scattering particle analyzer. As results, the particle size was 50-200 nm and dispersibility was monodisperse. It was found that the appropriate selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide a good yield and favorable physical properties of PLGA nanoparticles.

• Korean Journal of Medicinal Crop Science
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• v.17 no.4
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• pp.257-265
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• 2009

Phosphatidylcholine was used to encapsulate aqueous extracts of Centella asiatica, and its biological activity was compared with another aqueous extracts. Nanoparticle of C. asiatica was made by encapsulation to w/o type spherical liposome which of aqueous extracts seized with oil phase as 78.2 nm average diameter. Cytotoxicity of the nanoparticle was measured on human skin fibroblast cells, CCD-986sk, and showed lower cytotoxicity on 1.0 mg/$m{\ell}$ of highest concentration as 28% than that of another extracts. The nanoparticle showed the highest promotion of human B and T cell growth up to 138% and 135%, respectively, compared to the control. and the NK cell growth was promoted up to 8% higher than the control in proportion to secretion of IL-6 and TNF-$\alpha$ from immune cell growth. Also nanoparticle showed highest inhibition activity of hyaluronidase on 1.0 mg/$m{\ell}$ of highest concentration as 60.5%. It seems that because of enhanced biological application of aqueous extracts on cell through nano-encapsulation process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.4 s.334
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• pp.37-44
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• 2005

In this paper, a new type of the TC-to-BC encoder for high speed flash ADC's, called the Successive Selection Encoder (SSE), is proposed. In contrast to the conventional fat tree encoder based on OR operations, the W- outputs, in the new design, are obtained directly from TC inputs through simple MUX operations. The detailed structure of the SSE has been determined systematically by the method of the logical effort and the simulation oil Hynix 0.25um process. The theoretical and experimental results show that (1) it is not required to generate one-out-of-n signals, (2) the number of gates is reduced by the factor of 1/3, and (3) the speed is improved more than 2-times, compared to the fat tree encoder. It is speculated that the SSE proposed in this study is an effective solution for bottleneck problems in high speed ADCs.

• Proceedings of the Plant Resources Society of Korea Conference
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• v.18 no.1
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• pp.5-16
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• 2005

The herb of Allium victorialis var. platyphyllum (Liliaceae) has been used as an edible wild herb and to treat heart failure and gastritis. We have already reported antihyperlipidemic anti-tumor effects of this plant. To enlarge the commercial availability of this food, it was investigated whether the extracts of A. victorialis var.platyphyllum reduce hyperlipidemia and obesity or not. The plants tested in this experiment were collected from two eco-types of IS. Ullung and Mt. Odae cultivated at Pyongchang. Extracts were prepared by extracting the fresh leaves and those dried at $36^{\circ}C$ and $90^{\circ}C$, respectively. Pretreatment with the ethanolic extracts for two weeks (p.o.) reduced serum triglyceride-, total cholesterol- and LDL-cholesterol contents in rats induced by Triton WR-1339, respectively. Furthermore, oral administration of the extracts also inhibited the hyperlipidemia induced with oral diet of 30% corn oil. In the other attempt to find to alleviate the obesity, the model rats with obesity were induced by the high fat-diet for six weeks. Post-treatment with the extracts for two weeks significantly reduced the hyperlipidemia. Retroperitoneal-, epidymal- and total abdominal fat pad weights were considerably reduced at 100 mg/kg oral administration of the extracts. Increased feces lipid contents were also found in the rat treated with the extracts. The extract of Mt. Odae eco-type showed more potent activity than that of Is. Ullung one. These results suggest that use of the fresh leaves may lead to the higher activity in treatment of hyperlipidemia and obesity than of the dried one.