• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.128-134
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• 2014

Recently, design and construction of street tunnels tend to focus on cost reduction and preservation of nature. Accordingly, research is actively being carried out to quickly detect fires when they occur in tunnels, which have partially closed structures. Among such research, fire detection methods using optical fiber sensors have a wide bandwidth and fast transmission speed, while using light as a medium. Therefore, it does not receive electrical interference and there is almost no loss of information during transmission, while also having little noise as well. In relation to this, a fire monitoring system that can accurately detect the location of fires in real time using shape memory alloy and optical cables was developed in this study. In order to verify the developed method, light loss measurement test was conducted according to indoor temperature changes, while also conducting fire simulation tests by installing test beds in common underground zones with different external environments of temperature and distance. Upon carrying out experiments, the fire monitoring system developed in this study was found to be able to detect fires in long distance sections in real time.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.120-125
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• 2008

In this study, NiCoZn ferrites with the variation of sintering temperature and chemical composition were prepared by the coprecipitation. Microstructures Crystal structure of NiCoZn ferrites were analyzed by XRD and their electric magnetic characteristics were analyzed by LCR meter and their morphology observed by SEM. We identified that these powders have a typical NiCoZn spinel structure and nanoparticles average size of 40 nm. The impurity, the initial permeability and the Q factor value are the lowest of sintered NiCoZn ferrite at $1250^{\circ}C$. Also, we measured S-parameter for $(Ni_{0.4}Co_{0.1}Zn_{0.5})Fe_2O_4$ which showed a maximum reflection loss of -3.1 dB at 6 GHz for the 2 mm thick sample. From this result, we found that the NiCoZn ferrite can be used in ferrite microwave-absorbing application at a higher frequency region (> 6 GHz).

• Korean Journal of Environment and Ecology
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• v.33 no.4
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• pp.378-401
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• 2019

This study generated a list of plants in eight sections from the Baekdansa ticket office (874m) to Cheonjedan (1,560m) divided in the interval of 100m above sea level to examine the species diversity patterns and distribution changes of the vascular plants at different altitudes in Taebaeksan National Park. Four site surveys found a total of 385 taxa: 89 families, 240 genera, 345 species, 5 subspecies, 34 varieties, and 1 form. A result of analyzing the change of species diversity along elevational gradients showed that it decreased with increasing elevation and then increased from a certain section. A result of analyzing habitat affinity types showed that the proportion of forest species increased with increasing elevation. On the other hand, the ruderal species appeared at a high rate in the artificial interference section. A result of comparing the proportion of woody and herb plants showed that the woody plants gradually increased with elevation and rapidly decreased in the artificial interference section. On the other hand, the herb plants showed the opposite trend. A result of analyzing the change of distribution of species according to altitude with the DCA technique showed that the vascular plants were divided into three groups according to the elevation in order on the I axis with the boundaries at 900m and 1,300m above sea level. The arrangement of each stand from right to left along the altitude on the I axis with a significant correlation with warmth index (WI) confirmed that the temperature change along the altitude could affect the distribution of vascular plants, composition, and diversity. Therefore, the continuous monitoring is necessary to confirm ecological and environmental characteristics of vegetation, distribution ranges, changes of habitat. We expect that the results of this study will be used as the basic data for establishing the measurement measures related to the preservation of biodiversity and climate change.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.81-85
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• 2007

MnTe layers of high crystalline quality were successfully grown on Si(100) : B and Si(111) substrates by molecular beam epitaxy (MBE). Under tellurium-rich condition and the substrate temperature around $400^{\circ}C$, a layer thickness of $700{\AA}$ could be easily obtained with the growth rate of $1.1 {\AA}/s$. We investigated the structural, magnetic and transport properties of MnTe layers by using x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and physical properties measurement system (PPMS). Characterization of MnTe layers on Si(100) : B and Si(111) substrates by XRD revealed a hexagonal structure of polycrystals with lattice parameters, ${\alpha}=4.143{\pm}0.001{\AA}\;and\;c=6.707{\pm}0.001{\AA}$. Investigation of magnetic and transport properties of MnTe films showed anomalies unlike antiferromagnetic powder MnTe. The temperature dependence of the magnetization data taken in zero-field-tooling (ZFC) and field-cooling (FC) conditions indicates three magnetic transitions at around 21, 49, and 210 K as well as the great irreversibility between ZFC and FC magnetization in the films. These anomalies are attributable to a magnetic-elastic coupling in the films. Magnetization measurements indicate ferromagnetic behaviour with hysteresis loops at 5 and 300 K for MnTe polycrystalline film. The coercivity ($H_c$) values at 5 and 300 K are 55 and 44 Oe, respectively. In electro-transport measurements, the temperature dependence of resistivity revealed a noticeable semiconducting behaviours and showed conduction via Mott variable range hopping at low temperatures.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.4
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• pp.330-336
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• 2009

Purpose: We established radiolabeling conditions of NOTA and DOTA with a generator-produced PET radionuclide $^{68}$Ga and studied in vitro characteristics such as stability, serum protein binding, octanol/water distribution, and interference with other metal ions. Materials and Methods: Various concentrations of NOTA 3HCl and DOTA 4HCl were labeled with 1 mL $^{68}$GaCl$_3$ (0.18$\sim$5.75 mCi in 0.1 M HCl in various pH. NOTA 3HCl (0.373 mM) was labeled with $^{68}$GaCl$_3$(0.183$\sim$0.232 mCi/0.1 M HCl 1.0 mL) in the presence of CuCl$_2$, FeCl$_2$, InCl$_3$, FeCl$_3$, GaCl$_3$, MgCl$_2$ or CaCl$_2$ (0$\sim$6.07 mM) at room temperature. The labeling efficiencies of $^{68}$Ga-NOTA and $^{68}$Ga-DOTA were checked by ITLC-SG using acetone or saline as mobile phase. Stabilities, protein bindings, and octanol distribution coefficients of the labeled compounds also were investigated. Results: $^{68}$Ga-NOTA and $^{68}$Ga-DOTA were labeled optimally at pH 6.5 and pH 3.5, respectively, and the chelates were stable for 4 hr either in the reaction mixture at room temperature or in the human serum at 37$^{\circ}C$. NOTA was labeled at room temperature while DOTA required heating for labeling. $^{68}$Ga-NOTA labeling efficiency was reduced by CuCl$_2$, FeCl$_2$, InCl$_2$, FeCl$_3$ or CaCl$_3$, however, was not influenced by MgCl$_2$ or CaCl$_2$. The protein binding was low (2.04$\sim$3.32%). Log P value of $^{68}$Ga-NOTA was -3.07 indicating high hydrophilicity. Conclusion: We found that NOTA is a better bifunctional chelating agent than DOTA for $^{68}$Ga labeling. Although, $^{68}$Ga-NOTA labeling is interfered by various metal ions, it shows high stability and low serum protein binding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.774-783
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• 2007

This paper presents an integrated packaging antenna-diplexer module for wireless communication systems in the Cellular and SDMB band. The design and the realization of the proposed one are experimentally analyzed and discussed. It consists of a dual-resonance antenna and a diplexer with a multi-layer LTCC(${\varepsilon}_r=7.8,\;tan\;{\delta}=0.0043$) technology with integration capability and low loss. The dual-resonance antenna of the proposed module has the meander line structure for size reduction and has the shorting structure of an inverted F antenna to achieve good impedance matching. The diplexer of the proposed module was designed with the combination of low pass filter(LPF) and high pass filter(HPF). Decreasing the mutual interference between them provides a high isolation characteristic. The proposed antenna-diplexer module with dimensions of $27.5{\times}12.0{\times}2.2mm$ operates within a range from 813 MHz to 902 MHz for the cellular band and from 2,586 MHz to 2,655 MHz for the SDMB band. And the measured gain of the fabricated module is -1.96 dBi for Cellular band and -5.43 dBi for SDMB band. The parameters for the antenna-diplexer module are investigated and the several performances are discussed.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.20-40
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• 2003

Since unloaded Q-value of a high-temperature superconductor(HTS) filter is very high, a bandpass filter(BPF) and a lowpass filter(LPF) with an increase of pole numbers can be fabricated without an increase of an insertion loss(IL) ; recently a 70-pole BPF is developed in USA. They have an abrupt skirt property and an excellent attenuation level for out-of band. Moreover, they can be miniaturized when lumped element resonators or the slow-wave characteristic are used. Technology of fabricating a HTS epitaxial film as well as a film of a 4 inch area also makes the planar type filter with a various structure and an enhanced power handling capability possible. Recently, the HTS filter subsystems composed of a planar-type HTS filters, a GaAs-based LNA and a mini-cryocooler are developed. The extended receiver front- end subsystems for mobile radio communications decrease the noise-figure level of the communication system and the frequency interference interacted adjacent bands, and increase the efficiency of frequency and the capacity of communication system. In this paper, theory for developing the HTS filter, its kinds, its design rules, its characteristics are reviewed. The feature of the research and market trends related to the HTS filter systems for the receiver front-end subsystem of mobile base station are surveyed.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.17-23
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• 2017

Optical current sensors are suitable for operation in high voltage and high current environments such as power plants due to they are not affected by electromagnetic interference and have excellent insulation characteristics. However, as they operate in a harsh environment such as large temperature fluctuation and mechanical vibration, high reliability of the sensor is required. Therefore, many groups have been working on enhancing the reliability. In this work, an integrated optical current sensor incorporating polarization-rotated reflection interferometer is proposed. By integrating various optical components on a single chip, the sensor exhibits enhanced stability as well as the solution for low-cost optical sensors. Using this, we performed the characterization for the actual field application. By using a large power source, the current of 0.3 kA~36 kA was applied to the photosensor and the linear operation characteristics were observed. The error of the sensor was within $0{\pm}.5%$. Even when operating for a long time, the error range of the sensor was kept within $0{\pm}.5%$. In addition, the measurement of the frequency response over the range of 60 Hz to 10 kHz has confirmed that the 3-dB frequency band of the proposed OCT is well over 10 kHz.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.240-245
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• 2016

This study was conducted to predict the changes of potential distribution for invasive alien plant, Amaranthus viridis in Korea. The habitats of A. viridis were roadside, bare ground, farm area, and pasture, where the interference by human was severe. We used maximum entropy modeling (MaxEnt) for analyzing the environmental influences on A. viridis distribution and projecting on two different representative concentration pathways (RCP) scenarios, RCP 4.5 and RCP 8.5. The results of our study indicated annual mean temperature, elevation and precipitation of coldest month had higher contribution for A. viridis potential distribution. Projected potential distribution of A. viridis will be increased by 110% on RCP 4.5, 470% on RCP 8.5.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.55-69
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• 2013

The phytosocialogical study on the coastal sand dune vegetation of the East Coast was carried out. 180 phytosociological relev$\acute{e}$s of 62 sites in the East Coast were used in this study. In addition, already published syntaxa and the phytosociological hierarchy in Korea and Japan were used and comparative analyses of syntaxonomy, synecology, syngeography, and syndynamics were performed in the study. In this study, the flora was investigated 30 families, 66 genera, 77 taxa and 3 vegetation types were identified : the coastal drift-line annual communities (Calystegio soldanellae-Salsoletum komarovii), the dune glasslands communities (Elymo-Caricetum kobomugi, Carex kobomugi typical community, Elymus mollis community, Calystegia soldanella community, Zoysia macrostachya community, Cynodon dactylon community, Carex pumila community), and the dune shrubs communities (Linario-Viticetum rotundifoliae, Vitex rotundifolia community, Rosa rugosa community). The aspect of transition in the coastal sand dune vegetation of the East Coast were identified as follows : (1) reduced constancy degree and cover degree of Glehnia littoralis in each community; (2) lack of Ischaemum anthephoroides in Linario-Viticetum rotundifoliae (3) simplified species composition in Vitex rotundifolia community. Unstable habitat condition by external interference seemed to has caused the reduction of 2 taxa, Glehnia littoralis and Ischaemum anthephoroides, that usually grow in the second dune. In addition, we found changes in the distribution of the dune shrub communities influenced by rising temperature of the East Coast as results of the global warming. The results on the distribution of the dune shrub communities in this study demonstrated that the limit of the Rosa rugosa community made $0^{\circ}$ 44'N to the North and the vegetative limit of the Vitex rotundifolia community made $0^{\circ}$ 28'N to the North, respectively compared with the previously phytosociological studies. This study investigated the coastal sand dune vegetation, syntaxonomy, habitat condition and human disturbunce of the East Coast, and this will provide important information as basic data for the coastal ecosystem.