• Convergence Security Journal
• /
• v.13 no.2
• /
• pp.85-93
• /
• 2013

Today, the structure of terrorist organizations in the form of a variety of network complexity are evolving. However, terrorist organization not combining randomly generated network but preferential attachment a network. So, it's research should be preceded a better understanding about the characteristics and type of terror network for a effective counter-terrorism policy of law enforcement. In addition, the appropriate response strategy have to technique establish in an era of smart media. In particular, homegrown terrorist attacks on unspecified people without boundaries of countries and regions unlike the traditional terrorism. Also, homegrown terrorism are violence and criminal activity by new various of religion, politics, philosophy. Besides the extreme members of homegrown terror networks went grow up through the evolutionary process in the age of smart media. Law enforcement agencies must identify the terrorist network at the national level. Therefore, terror networks evolving in the online space, forming a radical homegrown terror organizations have access to the network. Intelligence community track terrorist networks and to block the negative aspects of the smart media outlets should be considered.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.05a
• /
• pp.104-104
• /
• 1999

The local heat transfer coefficient is experimentally investigated for the reflux condensation in a countercurrent flow between the steam-air mixture and the condensate. A single vertical tube has a geometry which is a length of 2.4m, inner diameter of 16.56mm and outer diameter of 19.05mm and is made of stainless steel. Air is used as a noncondensible gas. The secondary side is installed in the form of coolant block around vertical tube and the heat by primary condensation is transferred to the coolant water. The local temperatures are measured at 15 locations in the vertical direction and each location has 3 measurement points in the radial direction, which are installed at the tube center, at the outer wall and at the coolant side. In three different pressures, the 27 sets of data are obtained in the range of inlet steam flow rate 1.348 -3.282kg/hr, of inlet air mass fraction 11.8 -55.0%. The local heat transfer coefficient increases as the increase of inlet steam flow rate and decreases as the decrease of inlet air mass fraction. As an increase of the system pressure, the active condensing region is contracted and the heat transfer capability in this region is magnified. The empirical correlation is developed represented with the 165 sets of local heat transfer data. As a result, the Jacob number and film Reynolds number are dominant parameters to govern the local heat transfer coefficient. The rms error is 17. 7% between the results by the experiment and by the correlation.

• Animal cells and systems
• /
• v.1 no.1
• /
• pp.81-86
• /
• 1997

We studied the mechanism of arachidonic acid on the secretion of a neurotransmitter in rat pheochromocytoma PC12 cells. Arachidonic acid inhibited the 70 mM $K^+$-induced secretion of norepinephrine. Arachidonic acid also inhibited the 70 mM $K^+$-induced $Ca^{2+}$ mobilization which is due to the opening of the voltage-sensitive $Ca^{2+}$ channels (VSCC). Both the half maximal inhibitory concentration ($IC_{50}$) of the norepinephrine secretion and VSCC coincided at 30 uM. The major oxidized metabolites of arachidonic acid, prostaglandins did not mimic the inhibitory effect of arachidonic acid. Nordihydroguaiaretic acid (NDGA) and indomethacin which are inhibitors of lipoxygenase and cyclooxygenase, respectively, did not block the inhibitory effect of arachidonic acid. The results suggest that arachidonic acid serves as a signal itself, not in the form of metabolites. The pretreatment of various $K^+$ channel blockers such as 4-aminopyridine, tetraethylarnmonium, glipizide, or glibenclamide also did not show any effect on the inhibitory effect of arachidonic acid. Through these results we suggest that arachidonic acid regulates VSCC directly and affects the secretion of neurotransmitters.

• The Korean Journal of Ecology
• /
• v.26 no.4
• /
• pp.209-214
• /
• 2003

In order to clarify the successional trend and its characteristics of plant community in abandoned field in Cheju Island, we investigated the seral changes of vegetation height, coverage, growth form, species richness, diversity and dominance index along with the time lapse, and then compared with those of mainland researches. And in order to seek the overall trend of vegetation changes, we used cluster, TWINSPAN and PCA ordination techniques. The succession was characterized by the lower species number, lower vegetation height, longer period of herb dominant and later invasion of tree species. These results may come from that ecological traits of Cheju Island itself, and ecosystem fragmented influences that block a seed (propagule) transport. Sere of the dominant species was shown as follows: Mazus japonicus(0.5∼1 years)→Conyza sumatrensis (2 years)→Artemisia princeps var. orientalis(4 years)→Artemisia princeps var. orientalis, indigofera pseudotinctoria(5 years)→Rosa multiflora, Miscanthus sinensis, etc.(8 years)→Miscanthus sinensis(12 years)→Boehmeria nivea, Pueraria thunbergiana etc.(15 years)→Mallotus japonicus(20 years)→Litsea japonica, Machilus thunbergii (20 years<). Abandoned fields were classified into three groups according to time lapse; earlier stage(0∼1 years), middle stage(2∼8 years) and later stage(8∼20 years).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.2
• /
• pp.115-122
• /
• 2016

In this paper, wideband Ku-band downconverter was designed to receiver digital satellite broadcasting. The low-nose downconverter was designed to form four local oscillator frequencies(9.75, 10, 10.75 and 11.3 GHz) representing a low phase noise due to VCO-PLL with respect to input signals of 10.7 to 12.75 GHz and 3-stage low noise amplifier circuit by broadband noise matching, and to select intermediate frequency bands by digital control. The developed low-noise downconverter exhibited the full conversion gain of 64 dB, and the noise figure of low-noise amplifier was 0.7 dB, the P1dB of output signal 15 dBm, and the phase noise -85 dBc@10kHz at the band 1 carrier frequency of 9.75 GHz. The low noise block downconverter(LNB) for wideband digital satellite broadcasting designed in this paper can be used for global satellite broadcasting LNB.

• The Journal of Korean Academy of Prosthodontics
• /
• v.45 no.3
• /
• pp.389-400
• /
• 2007

Statement of problem. Use of the conventional dental impression procedure is problematic in patients who have difficulty opening their mouth, difficulty breathing through their nose or tendency to gag. Purpose. It is necessary to make individual trays more comfortable for patients during impression taking procedure. It was reported at the KAP Annual Meeting 2001 Seoul that an improved impression technique was suitable for this purpose. In this study, the accuracy of the improved dental impression method for implant was compared with the conventional dental impression method. Material and methods. An oral simulator was made from clear acrylic resin block which had similar form of edentulous ridge. For setting up the standard, five fixtures were installed on it. Study casts were made using two kinds of impression techniques. One was the conventional method that was taken using silicone impression material and an individual resin tray under connection of inter-fixture relation. The other was the improved method in which was the connection of the impression coping and the thermoformed polymethyl methacrylate tray. In addition, two different study casts were made from the improved impression body. The coordinates of the fixture on the study model were measured by three-dimensional coordinate measuring equipment. Then the distances between each fixture were calculated and compared with that of oral simulator. Accuracy of the each impression method was also assessed. Results. The differences of inter-fixture dimension between study casts and simulator in the improved impression technique showed $0.014{\pm}0.016mm$ and $0.017{\pm}0.022mm$, respectively and that of the conventional method was $0.017{\pm}0.014mm$. There was no significant difference between the improved impression technique and conventional method. Conclusion. The improved impression technique is useful for multiple support implants.

• Journal of Convergence for Information Technology
• /
• v.7 no.5
• /
• pp.95-102
• /
• 2017

Modular toys for creative education require functional blocks to create various types of movements. An active drive module and a lot of passive connection blocks are needed to express motion with combination. In this paper, we propose the design of modular toys to produce various creative movements and controller structure working with them. In order to facilitate the connection between the designed modules, a connection method and a suitable mechanism are suggested. We also dealt with the design of various types of sensor modules that can work in conjunction with modular toys. Using these toys, typical standard application form that can be imitated educationally is suggested and showed the usefulness of the modular toy by actually applying it with designed modules and components. The proposed method is applied to actual educational toys, and the operation is effectively performed by recording operation and playing repetitive operation.

• The Korean Journal of Zoology
• /
• v.38 no.4
• /
• pp.483-489
• /
• 1995

Retinoic acid was found to block membrane fusion of chick embryonic myoblasts in culture. This effed was dosedependent and could he reversed upon removal of the agent from the culture medium. Furthermore, the retinoic acid-mediated inhibition of membrane fusion was observed with the fusion competent cells but not with the cells that had already been committed for fusion, indicating that the effect of RA is differentiation stage-specific. However, retinoic acid showed little or no effect on the ability of the cells to form bipolar shape and to align along their axes. Neither the cell proliferation nor accumulation of muscle specific proteins, such as creatine kinase and tropomyosin, was impaired significantly. On the other hand, retinoic acid blocked the differentiation time~ependent loss of fibronectin, whose process is prerequisite for myoblast fusion. These results suggest that retinoic add acts as a specific inhibitor of membrane fusion by preventing the loss of fibronectin from the differentiating myoblasts.

• Archives of Pharmacal Research
• /
• v.29 no.8
• /
• pp.712-719
• /
• 2006

In this study, we prepared core-shell type nanoparticles of a poly(DL-lactide-co-glycolide) (PLGA) grafted-dextran (DexLG) copolymer with varying graft ratio of PLGA. The synthesis of the DexLG copolymer was confirmed by $^1H$ nuclear magnetic resonance (NMR) spectroscopy. The DexLG copolymer was able to form nanoparticles in water by self-aggregating process, and their particle size was around $50\;nm{\sim}300\;nm$ according to the graft ratio of PLGA. Morphological observations using a transmission electron microscope (TEM) showed that the nanoparticles of the DexLG copolymer have uniformly spherical shapes. From fluorescence probe study using pyrene as a hydrophobic probe, critical association concentration (CAC) values determined from the fluorescence excitation spectra were increased as increase of DS of PLGA. $^1H-NMR$ spectroscopy using $D_2O$ and DMSO approved that DexLG nanoparticles have core-shell structure, i.e. hydrophobic block PLGA consisted inner-core as a drug-incorporating domain and dextran consisted as a hydrated outershell. Drug release rate from DexLG nano-particles became faster in the presence of dextranase in spite of the release rate not being significantly changed at high graft ratio of PLGA. Core-shell type nanoparticles of DexLG copolymer can be used as a colonic drug carrier. In conclusion, size, morphology, and molecular structure of DexLG nanoparticles are available to consider as an oral drug targeting nanoparticles.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.36 no.3
• /
• pp.103-110
• /
• 2014

Purpose: The current gold standard for clinical jawbone formation involves autogenous bone as a graft material. In addition, demineralized dentin can be an effective graft material. Although demineralized dentin readily induces heterotopic bone formation, conventional decalcification takes three to five days, so, immediate bone grafting after extraction is impossible. This study evaluated the effect of vacuum ultrasonic power on the demineralization and processing of autogenous tooth material and documented the clinical results of rapidly processed autogenous demineralized dentin (ADD) in an alveolar defects patient. Methods: The method involves the demineralization of extracted teeth with detached soft tissues and pulp in 0.6 N HCl for 90 minutes using a heat controlled vacuum-ultrasonic accelerator. The characteristics of processed teeth were evaluated by scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Bone grafting using ADD was performed for narrow ridges augmentation in the mandibular area. Results: The new processing method was completed within two hours regardless of form (powder or block). EDS and SEM uniformly demineralized autotooth biomaterial. After six months, bone remodeling was observed in augmented sites and histological examination showed that ADD particles were well united with new bone. No unusual complications were encountered. Conclusion: This study demonstrates the possibility of preparing autogenous tooth graft materials within two hours, allowing immediate one-day grafting after extraction.