• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.71-74
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• 2007

With the changes of times the building materials tend to extend the demand for application under the special environment. Since high-ductile mortar is developed, the building materials show excellent performance like toughness, compression, tensile, and bending, etc. in the general concrete from the existing brittle point. And, recently they are widely used as repairing and reinforcing materials both at home and abroad because they are recognized as excellence like durability and fire-resistance. However, it is in a situation of creating problems in durability because it frequently happened deterioration of buildings that have already repaired and reinforced at a time when it requires reconstruction of recently deteriorated construction structure recently. Therefore, in this study improved with a more repair Material development and reinforcement of the second high-ductile mortar products for a variety of basic materials were presented want, research plans used include traditional repair materials and the newly developed PCM (polymer cement mortar) structural reinforcement type indicated that comparison. PCM analysis in order to present a rate depending on the types fiber 0, 1.2 and 2.0(%) at three levels and mixture water according to ratios of weight to Plain in the 2.0 and 1.85(kg) at two levels is set, the results were as follows. 1) This study has shown that PCM had excellent strain hardening behavior at the same time that the bending stress increased according to the fiber contents. 2) This study has shown that it had the durability performance due to the high substance transmission according to the fiber contents.

• Structural Engineering and Mechanics
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• v.52 no.3
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• pp.485-505
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• 2014

This study aimed to develop an approach to accurately predict the wind models and wind effects of large wind turbines. The wind-induced vibration characteristics of a 5 MW tower-blade coupled wind turbine system have been investigated in this paper. First, the blade-tower integration model was established, which included blades, nacelle, tower and the base of the wind turbine system. The harmonic superposition method and modified blade element momentum theory were then applied to simulate the fluctuating wind field for the rotor blades and tower. Finally, wind-induced responses and equivalent static wind loads (ESWL) of the system were studied based on the modified consistent coupling method, which took into account coupling effects of resonant modes, cross terms of resonant and background responses. Furthermore, useful suggestions were proposed to instruct the wind resistance design of large wind turbines. Based on obtained results, it is shown from the obtained results that wind-induced responses and ESWL were characterized with complicated modal responses, multi-mode coupling effects, and multiple equivalent objectives. Compared with the background component, the resonant component made more contribution to wind-induced responses and equivalent static wind loads at the middle-upper part of the tower and blades, and cross terms between background and resonant components affected the total fluctuation responses, while the background responses were similar with the resonant responses at the bottom of tower.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1549-1560
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• 2016

Today, all the countries of the world newly recognize importance of sea, which are focused on efforts for security of marine territory and fishes resources. Many of the coastal state, to strengthen the rights of their own country EEZ, marine survey and continental shelf development, travels through such maritime jurisdiction in the territorial sovereignty and the EEZ overlaps, deepening complex interests between neighboring countries cooperation activities of the fierce competition, the domestic and foreign been has been carried out. Under such circumstances, is devastated coastal of China, our territorial waters and EEZ has been violated more and more, in spite of the powerful crackdown maritime public power, illegal fishing more resistance intensified. They tend to be gradually organization, collectivization and atrocities. Currently, illegal fishing of Chinese fishing boats in the West Sea of Korea, including the waters near Yeonpyeong Island is prevalent as operating in the coast of the country. Furthermore regrettable one is illegal on a scale and the situation where South Korea of scale of damage caused by it have not been accurately grasp of the operation, but that there is damage of Korea official duty enforcement to crack down the increase to illegal operations year after year have occurred. Violent, illegal fishing of Chinese fishing boats, in order to eradicate the operations of insane at our sea, we investigated to the infringement situations of fisheries resources by multiple fields. each of problems presenting a specific preservation plan in accordance with the function and role of the maritime enforcement organization and other government organization the point. at the same time we will try to seek measures such as a scheme that it is possible to increase the capacity.

• Journal of Ginseng Research
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• v.42 no.3
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• pp.370-378
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• 2018

Background: Ginseng has been the subject of many experimental and clinical studies to uncover the diverse biological activities of its constituent compounds. It is a traditional medicine that has been used for its immunostimulatory, antithrombotic, antioxidative, anti-inflammatory, and anticancer effects. Ginseng may interact with concomitant medications and alter metabolism and/or drug transport, which may alter the known efficacy and safety of a drug; thus, the role of ginseng may be controversial when taken with other medications. Methods: We extensively assessed the effects of Korean Red Ginseng (KRG) in rats on the expression of enzymes responsible for drug metabolism [cytochrome p450 (CYP)] and transporters [multiple drug resistance (MDR) and organic anion transporter (OAT)] in vitro and on the pharmacokinetics of two probe drugs, midazolam and fexofenadine, after a 2-wk repeated administration of KRG at different doses. Results: The results showed that 30 mg/kg KRG significantly increased the expression level of CYP3A11 protein in the liver and 100 mg/kg KRG increased both the mRNA and protein expression of OAT1 in the kidney. Additionally, KRG significantly increased the mRNA and protein expression of OAT1, OAT3, and MDR1 in the liver. Although there were no significant changes in the metabolism of midazolam to its major metabolite, 1'-hydroxymidazolam, KRG significantly decreased the systemic exposure of fexofenadine in a dose-dependent manner. Conclusion: Because KRG is used as a health supplement, there is a risk of KRG overdose; thus, a clinical trial of high doses would be useful. The use of KRG in combination with P-glycoprotein substrate drugs should also be carefully monitored.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1051-1059
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• 2004

Two phase thermosyphone loop for electronics cooling are designed and manufactured to test its performance under the partial load and low environment temperature conditions. The thermosyphone device has six evaporators connected parallel for the purpose of cooling six power amplifier units (PAU) independently. The heater modules for simulating PAUs are adhered with thermal pad to the evaporator plates to reduce the contact resistance. There are unbalanced distributions of liquid refrigerant in the differently heated evaporators due to the vapor pressure difference. To reduce the vapor pressure differences caused by partial heating, two evaporators are connected each other using the copper tube. The pressure regulation tube successfully reduces these unbalances and it is good candidates for a field distributed systems. Under the low environment temperature operating condition, such as $-30^{\circ}C$, there may be unexpected subcooling in condenser. It leads the very low saturation pressure, and under this condition there exists explosive boiling in evaporator. The abrupt pressure rise due to the explosive boiling inhibits the supplement of liquid refrigerant to the evaporator for continuous cooling. Finally the cooling cycle will be broken. For the normal circulation of refrigerant there may be an optimum cooling air flow rate in condenser to adjust the given heat load.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.285-291
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• 2011

In this study the mechanical performance of the new wave dissipating block is evaluated through experiment and numerical analysis. Also, by selecting adequate reinforcement, the improvement of the structural performance is examined. The reinforcement is designed by predicting the amount of tensile force and the location where the tensile stress develops in the new wave dissipating block through numerical analysis. The new wave dissipating block is reinforced with the ordinary steel bars and the fiber reinforced plastic(FRP) bars which have advantages in ocean environment in terms of corrosion and fatigue. The test result shows that the fracture resistance of the un-reinforced concrete block is 350 kN which is about 6.2 times that of the weight of the block. All the test blocks which are reinforced by either steel of FRP bars show strength capacity of over 900 kN which is the maximum load of the test equipment. Although the single reinforcement with larger-diameter bars has advantage in terms of construction convenience, it is recommended to use multiple number of smaller-diameter bars in order to reduce the crack width.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.121-126
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• 1999

This paper describes a fabrication of Fe-dispersed hydrophilic magnetic fluid and its application to oil seal in combination with the Nd-permanent magnet. The results are as follows; 1) Using silica coated iron particle of magnetization of 125.5 emu/g (at 10 kOe) and the mean particle size of 100 $\AA$, after multiple adsorption to the surface of silica coated iron particle with oleic acid ion, D.B.S. and T.M.A. ion, hydrophilic Fe-magnetic fluid [70 %(g/∝)Fe, magnetization of 52 emu/g and viscosity of 1450 cp] can be produced by dispersing the iron particle in ethylene glycol solution. 2) The oil seal apparatus consisting of six stages of Nd-permanent magnet (3200 Gauss) and Fe-magnetic fluid [70 %(g/∝) Fe] showed an excellent pressure resistance of 7400 g/$\textrm{cm}^2$ under the gap between shaft and oil seal was 0.2 mm.

• Preventive Nutrition and Food Science
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• v.19 no.4
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• pp.247-260
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• 2014

The impact of folate on health and disease, particularly pregnancy complications and congenital malformations, has been extensively studied. Mandatory folic acid fortification therefore has been implemented in multiple countries, resulting in a reduction in the occurrence of neural tube defects. However, emerging evidence suggests increased folate intake may also be associated with unexpected adverse effects. This literature review focuses on contemporary issues of concern, and possible underlying mechanisms as well as giving consideration the future direction of mandatory folic acid fortification. Folate fortification has been associated with the presence of unmetabolized folic acid (PteGlu) in blood, masking of vitamin $B_{12}$ deficiency, increased dosage for anti-cancer medication, photo-catalysis of PteGlu leading to potential genotoxicity, and a role in the pathoaetiology of colorectal cancer. Increased folate intake has also been associated with twin birth and insulin resistance in offspring, and altered epigenetic mechanisms of inheritance. Although limited data exists to elucidate potential mechanisms underlying these issues, elevated blood folate level due to the excess use of PteGlu without consideration of an individual's specific phenotypic traits (e.g. genetic background and undiagnosed disease) may be relevant. Additionally, the accumulation of unmetabolized PteGlu may lead to inhibition of dihydrofolate reductase and other enzymes. Concerns notwithstanding, folic acid fortification has achieved enormous advances in public health. It therefore seems prudent to target and carefully monitor high risk groups, and to conduct well focused further research to better understand and to minimize any risk of mandatory folic acid fortification.

• Journal of Power Electronics
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• v.16 no.1
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• pp.297-309
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• 2016

Grid-connected inverters (GCIs) with an LCL output filter have the ability of attenuating high-frequency (HF) switching ripples. However, by using only grid-current control, the system is prone to resonances if it is not properly damped, and the current distortion is amplified significantly under highly distorted grid conditions. This paper proposes a synchronous reference frame equivalent proportional-integral (SRF-EPI) controller in the αβ stationary frame using the parallel virtual resistance-based active damping (PVR-AD) strategy for grid-interfaced distributed generation (DG) systems to suppress LCL resonance. Although both a proportional-resonant (PR) controller in the αβ stationary frame and a PI controller in the dq synchronous frame achieve zero steady-state error, the amplitude- and phase-frequency characteristics differ greatly from each other except for the reference tracking at the fundamental frequency. Therefore, an accurate SRF-EPI controller in the αβ stationary frame is established to achieve precise tracking accuracy. Moreover, the robustness, the harmonic rejection capability, and the influence of the control delay are investigated by the Nyquist stability criterion when the PVR-based AD method is adopted. Furthermore, grid voltage feed-forward and multiple PR controllers are integrated into the current loop to mitigate the current distortion introduced by the grid background distortion. In addition, the parameters design guidelines are presented to show the effectiveness of the proposed strategy. Finally, simulation and experimental results are provided to validate the feasibility of the proposed control approach.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.439-446
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• 2008

We have developed a method to evaluate pumping rates from a system of pumping-well family. For a given system actual pumping rates depend on pump characteristics and the sum of the static head and the dynamic head. The static head is the elevation difference between the natural groundwater level and the outlet of the pipeline that connects all the wells. Major components of the dynamic head are groundwater drawdown in the well and pipeline head loss. The dynamic head and the pump characteristics depend on the pumping rates. Actual pumping rates are determined at the intersections of the system total-head curves and the pump characteristic curves. The Newton-Raphson's method is used to solve the nonlinear simultaneous equations. The method is applied to a hypothetical well family. Impacts of various design and operational parameters on the pumping rates are analyzed.