• Journal of Korean Society of Forest Science
• /
• v.101 no.2
• /
• pp.226-235
• /
• 2012

Floristic composition and phytosociological studies in Mt. Gwaebyung and Galmi-Bong were investigated to classify forest vegetation and distribution of vascular plants. We investigated two study sites from April to September, 2011. Total 477 taxa with 93 families, 279 genera, 408 species, 4 subspecies, 56 varieties and 9 forms were distributed in Mt. Gwaebyung and Galmi-Bong. Korean endemic species were composed of 8 families with 11 genera and 11 species. The plant species which is designated as protected species by the Ministry of Environment, Korea was 2 families, 2 genera and 2 species. Also plant species which is designated by the Korea National Arboretum was 16 taxa with 13 families, 14 genera, 15 species and 1 variety. A naturalized plants were 17 taxa. The Naturalization index and Urbanization index were 3.6% and 5.3% respectively. Pteridophyta-calculation (Pte-Q) was 1.00. Life form spectra was $H-D_4-R_5-e$ type and the highest percentage of useful plant resources were medicinal plant (77.5%). The forest vegetation in Mt. Gwaebyung and Galmi-bong was classified into 1 order, 1 alliance and 4 communities; Rhododendro - Quercetalia mongoliaceae, Lindero-Quercion mongolicae, Quercus mongolica Typical Community, Pinus densiflora-Quercus mongolica Community, Larix kaempferi Community and Sasa borealis-Quercus mongolica Community.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.10
• /
• pp.1169-1176
• /
• 2010

The RF front-end for L1/L2 dual-band Global Positioning System(GPS) receiver is presented in this paper. The RF front-end(down-converter) using low IF architecture consists of a wideband low noise amplifier(LNA), a current mode logic(CML) frequency divider and a I/Q down-conversion mixer with a poly-phase filter for image rejection. The current bleeding technique is used in the LNA and mixer to obtain the high gain and solve the head-room problem. The common drain feedback is adopted for low noise amplifier to achieve the wideband input matching without inductors. The fabricated RF front-end using $0.18{\mu}m$ CMOS process shows a gain of 38 dB for L1 and 41 dB for L2 band. The measured IIP3 is -29 dBm in L1 band and -33 dBm in L2 band, The input return loss is less than -10 dB from 50 MHz to 3 GHz. The measured noise figure(NF) is 3.81 dB for L1 band and 3.71 dB for L2 band. The image rejection ratio is 36.5 dB. The chip size of RF front end is $1.2{\times}1.35mm^2$.

• The Journal of Korea Assosiation for Disability and Oral Health
• /
• v.14 no.1
• /
• pp.17-21
• /
• 2018

Williams syndrome (WS) is a rare congenital disorder which is caused by microdeletion of approximately 1.6 MBP from the long arm of chromosome 7 at 7q11.23. It is characterized by cardiovascular anomalies, elfin face and mental retardation. The most typical oral signs in patient with WS are hypodontia, reduced mesio-distal dimensions both in the primary and permanent teeth, macroglossia, excessive interdental spacing, enamel hypoplasia and enamel hypomineralization. The majority of children with WS have mild to moderate mental retardation, generalized anxiety disorder, hyperactivity disorder and sensitivity to sounds. The purpose of this presentation is to describe dental treatment for a child with WS. A 9-year-old boy diagnosed with WS had caries on his first permanent molars. Because of the poor cooperation, these teeth were filled temporarily with glass ionomer, and treatment under general anesthesia was planned. Under general anesthesia, caries treatment of first permanent molar and extraction of primary molar was successfully performed and there was no postoperative complications related to general anesthesia. Open bite, hypodontia, excessive dental space, enamel hypoplasia, enamel hypomineralization were observed which were characteristic in WS.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.3
• /
• pp.685-690
• /
• 2013

This paper has proposed a multi-channel and wide gain-range baseband circuit blocks for the IEEE 802.15.4g MR-OFDM SUN systems. The proposed baseband circuit blocks consist of two negative-feedback VGAs, an active-RC 5th-order chebyshev low-pass-filter, and a DC-offset cancellation circuit. The proposed baseband circuit blocks provide 1 dB cut-off frequencies of 100 kHz, 200 kHz, 400 kHz, and 600 kHz respectively, and achieve a wide gain-range of +7 dB~+84 dB with 1 dB step. In addition, a DC-offset cancellation circuit has been adopted to mitigate DC-offset problems in direct-conversion receiver. Simulation results show a maximum input differential voltage of $1.5V_{pp}$ and noise figure of 42 dB and 37.6 dB at 5 kHz and 500 kHz, respectively. The proposed I-and Q-path baseband circuits have been implemented in $0.18-{\mu}m$ CMOS technology and consume 17 mW from a 1.8 V supply voltage.

• Journal of Oral Medicine and Pain
• /
• v.38 no.2
• /
• pp.215-219
• /
• 2013

The descending control system is composed of a group of structures in the midbrain, medulla oblongata and pons that form a network of descending inhibitory projections. In the clinical setting, it has been shown that the application of a electrical counterirritant to these structures and diminishes the pain in patients. Thus, depression and anxiety have been shown to predict the development of chronic neuropathic pain state. These factors could influence pain might also involve descending controls. Interestingly, reduced descending controls are seen in patients with irritable bowel syndrome and theses patients had greater anxiety, depression compared to controls. And, the influence of anxiety on the chronicity of pain and on the descending control pathways should be tested in animal models, using modern techniques. Given this Knowledge, it is no wonder that pain is a highly personal experience that is susceptible to a variety of biologic, pharmacologic, and environmental influences.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.2
• /
• pp.121-130
• /
• 2010

Metals and sulfate can be considerably dissolved at low pH condition in the acid mine drainage(AMD) and it would make an environmental problems. There are only few of acid mine drainage treatment systems in Korea which are operating, but these still have an effect on the surrounding stream. In this study, quantification of indicator microorganisms was conducted to judge the environmental impact of AMD on microflora by quantitative real-time PCR in the drainage samples of four mines and the water samples of each surrounding stream. Two species of iron reducing bacteria(Rhodoferax ferrireducens T118 and Acidiphilium cryptum JF-5) were selected for indicator bacteria based on 16S rRNA cloning analysis, and sulfate reducing bacteria(Desulfosporosinus orientus), iron and sulfur oxidizing bacteria(Acidothiobacillus ferrooxidans) and iron oxidizing bacteria(Leptosprillum ferrooxidans) were included into indicator since these were found in the previous studies on the mining area. Thereafter, the comparative analysis of four mines were established by the microbiological variation index and it was determined that the biological environment effect of AMD is highest in Samtan mine which doesn t contain treatment system by the value.

• Korean Journal of Environment and Ecology
• /
• v.20 no.2
• /
• pp.114-121
• /
• 2006

To investigate the vegetation structure of mountain ridge from Miwangjae to Cheonwhangbong, 11 plots($2000m^2$) set up with random sampling method were surveyed. Three groups of Quercus mongolica community, Quercus mongolica-Styrax japonica community, Q. mongolica-Pinus densiflora community were classified by cluster analysis. Quercus mongolica was a major woody plant species in the ridge area from Miwangjae to Cheonwhangbong, and Styrax japonica and Pinus densiflora was partly occupied. High positive correlations was proved between Prunus sargentii and Euonymus alatus for. ciliato-dentatus; Quercus serrata and Euonymus alatus; Sorbus alnifolia and Euonymus alatus, Magnolia sieboldii; Acer pseudo-sieboldianum and Euonymus alatus for. ciliato-dentatus; Rhododendron schlippenbachii and Euonymus alatus for. ciliato-dentatandus; Euonymus alatus and Lindera obtusiloba, Castanea crenata, Lindera erythrocarpa; Lespedeza bicolor and Rhododendron schlippenbachii; Castanea crenata and Magnolia sieboldii; Magnolia sieboldii and Lindera erythrocarpa, and relatively high negative correlations was proved between Rhododendron schlippenbachii and Euonymus alatus; Lespedeza bicolor and Castanea crenata; Stephanandra incisa and Magnolia sieboldii; Rhododendron yedoense var. poukhanense and Lindera erythrocarpa; Euonymus alatus for. ciliato-dentatus and Magnolia sieboldii; Fraxinus sieboldiana and Sapium japonicum; Prunus sargentii and Lespedeza maximowiczii; Lespedeza maximowiczii and Lindera erythrocarpa. Species diversity(H') of investigated groups was ranged $2.3225{\sim}2.7721$, and it was relatively low value compared to that of mountain ridge area of other national parks.

• Journal of the Korean Magnetics Society
• /
• v.7 no.5
• /
• pp.237-242
• /
• 1997

The microstructure and soft magnetic properties of as-deposited Fe-Hf-O thin film alloys, which are produced at $P_{O2}=10%$ by rf magnetron sputtering method in $Ar+O_2$ mixed gas atmosphere, is investigated. Newly developed $Fe_{82}Hf_{3.4}O_{14.6}$ film exhibits good soft magnetic properties with $4{\pi}M_s=17.7$ kG, $H_c=0.7$ Oe and ${\mu}_{eff}$(0.5~100MHz)=2,500, respectively. The Fe-Hf-O films are composed of $\alpha$-Fe nanograins and amorphous phase with larger amounts of Hf and O elements which chemically combine each other. With increasing Hf area fraction, Hf and O contents increased proportionally. It was considered that O content in films was determined by Hf contents, because O was chemically combined with Hf. It results from decreasing the $\alpha$-Fe grain size by precipitates (Hf and O), high electrical resistivity. The $Fe_{82}Hf_{3.4}O_{14.6}$ film exhibits the quality factor (Q=$\mu$'/$\mu$") of 25 at 20 MHz. These good frequency characteristics are considered to be superior to other films already reported.o other films already reported.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.3
• /
• pp.478-486
• /
• 1998

$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\le \textrm x\le0.8)$ system was prepared by reaction of $CaCO_3,\;LaO_3,\;Nd_2CO_3$ and ,TEX>$TiO_2$ mixture at 1673 K, which can be applied for microwave dielectric ceramic materials. The lattice parameters of(1-x))$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\le \textrm x\le0.8)$ system increased with the increase of x. Its structure was investigated by Rietveld profile-analysis of XRD in detail. Cations $ La^{3+}$ and Nd^{3+}$ were located at the $Ca^{2+}$ site in the range of $0\le \textrm x\le0.8$. crystal structure in $;(0\le \textrm x\le0.6)$ maintained space group Pnma with CaTiO_3 structure. The tiled and distorted $TiO_6$ was gradually released with the increase of x in $0\le \textrm x\le0.6$ .The structure was changed to a new space group of $Pmn2_1$ at the x value of 0.8. The relative dielectric constant $(\epsilon_r)$ of $(1-x)CaTiO_3-x(La_{1/3} Nd_{1/3})TiO_3$ ($(0\le \textrm x\le0.8)$) system was exponentially decreased by with the increased of x. The temperature coefficient of resonant frequency $(\tau_f)$ decreased with the increase of x in $0\le \textrm x\le0.6$ and then increased again at x=0.8 due to the change of crystal structure. The value of Q$\cdot f_o$ was 13800 (GHz) at x=0.2 and was very low under 2000 (GHz) in 0.4$\leq$x$\leq$0.8.

• The Journal of Engineering Geology
• /
• v.15 no.3
• /
• pp.337-348
• /
• 2005

Jurassic granite from Pocheon area were tested to investigate the effect of microcracks on mechanical properties of the granite. Three oriented core specimens were used for uniaxial compressive tests and each core specimen are perpendicular to the axes'R'(rift plane),'c'(grain plane) and'H'(hardway plane), respectively Among vacious elastic constants, the variation of Poisson's ratio as function of the directions was examined. From the related chart between ratio of failure strength and Poisson's ratio, H-specimen shows the highest range in Poisson's ratio and Poisson's ratio decreases in the order of C-specimen and R-specimen. The curve pattern is nearly linear in stage $I\simIII$ but the slope increases abruptly in stage H-3. As shown in the related chart, diverging point of a curve is formed when ratio of failure strength is $0.92\sim0.96$ Stage IV -3 is out of elastic region. The behaviour of rock in the four fracturing stages was analyzed in term of the stress-volumetric strain me. From the stress increment-volumetric strain equations governing the behaviour of rock, characteristic material constants, a, n, Q, m and $\varepsilon_v^{mcf}$, were determined. Among these, inherent microcrack porosity$(a, 10^{-3})$ and compaction exponent(n) in the microcrack closure region(stage I ) show an order of $a^R(3.82)>a^G(3.38)>a^H(2.32)\;and\;n^R(3.69)>n^G(2.79)>n^H(1.99)4, respectively. Especially, critical volumetric microcrack strain($\varepsilon_v^{mcf}$) in the stage W is highest in the H-specimen, normal to the hardway plane. These results indicate a strong correlation between two major sets of microcracks and mechanical properties such as Poisson's ratio and material constants. Correlation of strength anisotropy with microcrack orientation can have important application in rock fracture studies.