• The Korea Journal of Herbology
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• v.23 no.2
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• pp.179-192
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• 2008

Objectives : Draconis Resina (DR) has been used as a traditional Korean herbal medicine since ancient times, and today it is used as a medication for wounds, tumors, diarrhea, rheumatism, in the itching of insect bites and with other conditions in the folk medicine. The aim of this study was to determine whether fractionated extracts of DR inhibit free radical generation, intracellular oxidation, production of nitrite, an index of NO, PGE2, iNOS, COX-2 and proinflammatory cytokines in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages, Methods : DR extract prepared with methanol, and then fractionated with hexane, dichloromethane, ethylacetate, n-butanol and water. Inhibitory effect of DR onto free radical generation was determined by measuring DPPH, superoxide anions and nitric oxide scavenging activities in vitro. Cytotoxic activity of extracts on RAW 264.7 cells was measured using 5-(3-caroboxymeth-oxyphenyl)-2H-tetra-zolium inner salt (MTS) assay. Intracelluar oxidation was analysed by DCF-DA assay. The nitric oxide (NO) production was measured by Griess reagent system. The levels of iNOS and COX-2 expression were confirmed by western blot. And proinflammatory cytokines were measured by ELISA kit. Results : Our results indicated that fractionated extracts, especially dichloromethane and ethyl acetate extracts, significantly inhibited free radical generation, the LPS-induced H202, NO, PGE2 production and iNOS, COX-2 expression accompanied by an attenuation of TNF-${\alpha}$, IL-$1{\beta}$ and IL-6 formation in macrophages. Conclusions : Our results indicate that dichloromethane and ethyl acetate extracts of DR have potential as an agent of chronic inflammatory diseases.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.362-369
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• 2013

Two-phase flow is frequently observed in many industries such as nuclear power plants and oil transportation. Two-phase flow regime depends on the flow rates, the fluid properties and the structure of flow channels. Since the identification of the flow regime is of great importance in the system design and the safety analysis, a number of theoretical and experimental investigations have been performed. This paper presents a basic research on the characteristics of each flow regime and transition boundary in the two-phase flows. The flow regime of the upward air-water flow in the vertical tube, 30 mm in the inner diameter, is distinguished by using the high-speed camera and the Wire-mesh sensor(WMS). The identified experimental data are compared with the flow regime maps proposed by Taitel et al, Mishima and Ishii. Even though there is slight difference in the transition boundary, the experimental data show general agreement with these flow regime maps.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.422-434
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• 2020

This study aims to analyze the types of college admission that should be strengthened or reflected in universities and to suggest the direction of entrance examination by identifying the actual implementation of the literature-science integrated 2015 revised national curriculum. In order to do so, in-depth interviews on the current state were executed to five curriculum experts. As a result of the interview, it was found that the introduction and adoption of clear admission types look into the inner side of high school life are necessary. Also, it is required to establish specific criteria for student selection expand in-depth interviews related to learning activities in high school, strengthen evaluation competence of admission staffs and recruit more evaluation personnel. In addition, in order to revitalize the 2015 revised curriculum, it is necessary to evaluate how many subjects, especially in career-related subjects, students have taken in order to expand the school record-focused system. For this, it is required to extract evaluation elements and criteria of universities that can grasp continuous and active role performance, and to design a typical design that can objectively judge them. This study can contribute to the settlement of the selection process that can revitalize public education. And it is expected that the selection of the talents desired by the university will be used as a possible basic data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.92-100
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• 2017

The Helicopter MRA Control Rod System has the important function of controlling the speed, height, and direction of helicoptersby adjusting the main rotor disc. However, the ingress of water into the inner control rod can cause ice damage in the rod during winter operation and also corrosion;these defects need to be rectified. The water flowed into the control rod through the upper side space, and the rod was cracked during icing expansion occurring at low temperature. The corrosion occurred due to the lack of coating process during the manufacturing process. To resolve these problems, the upper rod was sealed to prevent water inflow and a coating process was added to prevent corrosion. These solutions were verified by awaterproof test and a salt fog test. The phenomena, causes and measures were reviewed and the methods of improvement were established and proven. This proposed technology to prevent water infiltration and corrosion will contribute to the safety of rotary wing aircraft.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.9-16
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• 2016

Buried pipe system is subject to leak or rupture due to internal and external defects with age. Especially, if the pipeline is designed for pressurized gas, the leak can wreak a devastating on its surrounding area. The current method of setting up underground gas pipeline is based on OGP criteria of applying one tenth of the inner pipe pressure. The criteria is applied irrespective of their burial depth or pipe's properties. At times, even the whole safety measures are totally ignored. Considering the magnitude of possible damage from a gas leakage, a precise analytical tool for the risk assessment is urgently needed. The study was conducted to assess possible scenarios of gas accidents and to develop a computer model to minimize the damage. The data from ETA was analyzed intensively, and the model was developed. The model is capable of predicting jet fire influence area with comprehensive input parameters, such as burial depth. The model was calibrated and verified by the historic accident data from Edison Township, New Jersey, the United States. The statistical model was also developed to compare the results of the model in this study and the existing OGP model. They were in good agreement with respect to damage predictions, such as radiation heat coming from 10 meters away from the heat source of gas flame.

• Restorative Dentistry and Endodontics
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• v.29 no.5
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• pp.446-453
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• 2004

The aim of this study was to evaluate the shaping abilities of four different rotary nickel-titanium instruments with anticurvature motion to prepare root canal at danger zone by measuring the change of dentin thickness in order to have techniques of safe preparation of canals with nickel-titanium files. Mesiobuccal and mesiolingual canals of forty mesial roots of extracted human lower molars were instrumented using the crown-down technique with ProFile, $GT^{TM}$ Rotary file, Quantec file and $ProTaper^{TM}$. In each root, one canal was prepared with a straight up-and-down motion and the other canal was with an anticurvature motion. Canals were instrumented until apical foramens were up to size of 30 by one operator. The muffle system was used to evaluate the root canal preparation. After superimposing the pre- and post-instrumentation canal. change in root dentin thickness was measured at the inner and outer sides of the canal at 1. 3, and 5 mm levels from the furcation. Data were analyzed using two-way ANOVA. Root dentin thickness at danger zone was significantly thinner than that at safe zone at all levels (p < 0.05). There was no significant difference in the change of root dentin thickness between the straight up-and-down and the anticurvature motions at both danger and safe zones in all groups (p > 0.05). ProTaper removed significantly more dentin than other files especially at furcal 3 mm level of danger and safe zones (p < 0.05) Therefore, it was concluded that anticurvature motion with nickel-titanium rotary instruments does not seem to be effective in danger zone of lower molars.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.171-176
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• 2009

Purpose : To investigate the effect of coating material in RF coil, which is one of main parts in MRI machine, on the Q-factor and SNR(signal-to-noise ratio) in MR images. Materials and Methods : RF coils with inner diameter of 1.7 mm were made by using copper wires coated with polyester, polyurethane, polyimide, polyamideimide, and polyester-imide, and by using copper wires in which coating materials had been removed. Q-factors of the RF coils were measured by network analyzer, and SNR values in the spin-echo MR images obtained by 600 MHz (14.1 T, Bruker DMX600) micro-imaging system for the coated and uncoated cases. Results : The measured SNRs were almost same for the RF coils with coat-removed copper wires, however SNRs and Q-factors were different for the coated cases depending on the coating material. They were maximized in the polyurethane-coated case in which the SNR was > 30% greater than polyester-coated case. Conclusion : We made solenoid-type RF coils which were easily used for MR micro-imaging in Bruker MRI probe. There was a significant coating-material dependence in the measured Q values and SNRs for the home-made RF coils. The study demonstrated that the choice of coating material of RF coil may be a critical factor in the MRI sensitivity based on SNR value.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.17-24
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• 2007

In this paper, we propose the sub-cell reuse partitioning among relays as an efficient resource reuse scheme in the relay-based OFDMA systems. If the frequency resource is reused among relays aggressively, we can increase the cell throughput. However, the interferences due to the frequency reuse may cause the fairness decrease due to the SINR degradation especially at the edge of RS sub-cells. In this paper, to make the cell throughput and fairness performance improved at the same time, we propose a sub-cell reuse partitioning scheme that divides a relay sub-cell into inner zone for aggressive reuse and outer zone for sparse reuse. The performance of the proposed scheme has been analyzed by computer simulation. We also applied a scheduling algorithm that can work together with the proposed sub-cell reuse partitioning scheme. Simulation results show that the proposed scheme can improve both the throughput and the fairness performances. In particular, when the scheduling is applied for the improvement of fairness, it is shown that the throughput performance can be enhanced more efficiently by the proposed scheme.

• Applied Microscopy
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• v.39 no.2
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• pp.81-87
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• 2009

Diabetic retinopathy is one of major complications of diabetes mellitus, which is associated with the dysfunction of retina. It has been reported that the onset of diabetic retinopathy is related to the activation of renin-angiotensin system (RAS). Angiotensin converting enzyme (ACE), which converts angiotensin I into angiotensin II, is a key component of RAS. Among many growth factors, vascualr endothelial growth factor (VEGF) is an important cytokine in the neovasculization of retina, which is a characteristics of diabetic retinopathy. However, the relationship between ACE and VEGF was not elucidated in diabetic retinopathy. Thus, this study was conducted to examine the protective effect of captopril, an ACE inhibitor, in the retina of streptozotocin (STZ)-treated diabetic rats. In present study, STZ-treated diabetic rats exhibited the increase of VEGF levels in serum and retina. The serum levels of VEGF in STZ-treated diabetic rats was not blocked by the treatment of captopril. However, the retina levels of VEGF in STZ-treated diabetic rats was blocked by the treatment of captopril, suggesting the local action of captopril in retina. Immunohistochemical analysis also revealed that the retina of STZ-treated diabetic rats manifested the increase of ganglion cell layers, outer nuclear layers, and inner nuclear layers, which were also prevented by the treatment of captopril. In conclusion, captopril prevented the expression of VEGF in the retina of STZ-treated diabetic rats.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.9-15
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• 2006

At the adjacent sea area of Busan Central Wharf, a variety of vessels, such as middle-large passenger ships, small hugh speed crafts, container ships, cargo ships and working boats as well as small miscellaneous vessels are freely sailing comparatively without special rules and marine traffic control. In this research, we analyzed traffic stream and navigational characteristics cf main traffic route based on statistics and distribution of tracks by ship's type and tonnage cf the passing vessels after conducting marine traffic survey twice using exclusive software. We examined the traffic safety of the passing vessels by classifying the sea area by each function based on the analysis about this traffic situation, and analyzing the effect by designating 'Inner passage'. We also studied the plan for the effective rearrangement cf Central Wharf considering basically the traffic safety of arrival and departure in a point of view of navigators.