• 한국환경과학회지
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• 제19권11호
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• pp.1423-1436
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• 2010

The effects of meteorological and reclaiming conditions on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the k-$\varepsilon$ turbulence closure scheme based on the renormalization group (RNG) theory. Twelve numerical experiments with different meteorological and reclaiming conditions are performed. For identifying the meteorological characteristics of the target area and providing the inflow conditions of the CFD model, the observed data from the automatic weather station (AWS) near the target area is analyzed. Complicated flow patterns such as flow distortion, horse-shoe vortex, recirculation zone, and channeling flow appeared due to the topography and buildings in the domain. Specially, the flow characteristics around the reclamation area are affected by the reclaiming height, reclaiming size and windbreak height. Reclaiming height affected the wind speed above the reclaiming area. Windbreak induces more complicated flow patterns around the reclaiming area as well as within the reclaiming area. In front of the windbreak, flow is distorted as it impinges on the windbreak. As a result, upward flow is generated there. Behind the windbreak, a secondary circulation, so called, a recirculation zone is generated and flow is reattached at the end of the recirculation zone (reattachment point). At the lower part of the recirculation zone, there is a reverse flow toward the windbreak. Flow passing to the reattachment point starts to be recovered. Total amounts of suspended particles are calculated using the frictional and threshold frictional velocities, erosion potential function, and the number of surface disturbance. In the case of a 10 m-reclaiming and northerly wind, the amount of suspended particles is largest. In the presence of 5 m windbreak, the friction velocity above the reclaiming area is largely reduced. As a result, the total amount of the suspended particles largely decreases, compared to the case with the same reclaiming and meteorological conditions except for the windbreak The calculated suspended particle amounts are used as the emission rate of the dispersion model simulations and the dispersion characteristics of the suspended particles are analyzed.

• Asian Journal of Atmospheric Environment
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• 제12권3호
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• pp.274-288
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• 2018

Quantitative data of 50 non-polar organic compounds constituting $PM_{2.5}$ were continuously collected and analyzed from June 2016 to October 2017 (approximately 17 months) at Ichihara, one of the largest industrial areas in Japan. Target non-polar organic compounds including 21 species of polycyclic aromatic hydrocarbons (PAHs), 24 species of n-alkanes and 5 species of phthalate esters(PAEs) were simultaneously measured by gas chromatography/mass spectrometry. Basically, the average concentrations of the total PAHs, n-alkanes and PAEs in each season remained nearly level, and seasonal variations were little throughout the study period. These results suggest that the emission sources, which are not influenced by the seasons, are the dominant inputs for the target organic compounds. Diagnostic ratios of PAHs, assessment of n-alkane homologue distributions, carbon preference index, and the contribution of wax n-alkanes from plants were used to estimate source apportionments. These results indicate that anthropogenic sources were the main contributor for most PAHs and n-alkanes throughout the study period. The concentrations of PAEs selected in this study were low because emission amounts of these chemicals were little within the source areas of the sampling site. To our knowledge, this study is the first attempt to simultaneously measure a high number of non-polar organic compounds in $PM_{2.5}$ collected from the ambient air of Japan, and the resultant data will provide valuable data and information for environmental researchers.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.471-479
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• 2017

White spot syndrome virus (WSSV) is a major threat to the shrimp farming industry and so far there is no effective therapy for it, and thus early diagnostic of WSSV is of great importance. However, at the early stage of infection, the extremely low-abundance of WSSV DNA challenges the detection sensitivity and accuracy of PCR. To effectively detect low-abundance WSSV, here we developed a pre-amplification PCR (pre-amp PCR) method to amplify trace amounts of WSSV DNA from massive background genomic DNA. Combining with normal specific PCR, 10 copies of target WSSV genes were detected from ${\sim}10^{10}$ magnitude of backgrounds. In particular, multiple target genes were able to be balanced amplified with similar efficiency due to the usage of the universal primer. The efficiency of the pre-amp PCR was validated by nested-PCR and quantitative PCR, and pre-amp PCR showed higher efficiency than nested-PCR when multiple targets were detected. The developed method is particularly suitable for the super early diagnosis of WSSV, and has potential to be applied in other low-abundance sample detection cases.

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.138-144
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• 2016

Purpose: Phosphorus is an essential element for water quality control. Excessive amounts of phosphorus causes algal bloom in water, which leads to eutrophication and a decline in water quality. It is necessary to maintain the optimum amount of phosphorus present. During the last decades, various studies have been conducted to determine phosphorus content in water. In this study, we present a comprehensive overview of colorimetric, electrochemical, fluorescence, microfluidic, and remote sensing technologies for the measurement of phosphorus in water, along with their working principles and limitations. Results: The colorimetric techniques determine the concentration of phosphorus through the use of color-generating reagents. This is specific to a single chemical species and inexpensive to use. The electrochemical techniques operate by using a reaction of the analyte of interest to generate an electrical signal that is proportional to the sample analyte concentration. They show a good linear output, good repeatability, and a high detection capacity. The fluorescence technique is a kind of spectroscopic analysis method. The particles in the sample are excited by irradiation at a specific wavelength, emitting radiation of a different wavelength. It is possible to use this for quantitative and qualitative analysis of the target analyte. The microfluidic techniques incorporate several features to control chemical reactions in a micro device of low sample volume and reagent consumption. They are cheap and rapid methods for the detection of phosphorus in water. The remote sensing technique analyzes the sample for the target analyte using an optical technique, but without direct contact. It can cover a wider area than the other techniques mentioned in this review. Conclusion: It is concluded that the sensing technologies reviewed in this study are promising for rapid detection of phosphorus in water. The measurement range and sensitivity of the sensors have been greatly improved recently.

• 한국분말재료학회지
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• 제18권6호
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• pp.552-561
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• 2011

This study attempted to manufacture a Cu-15 at.%Ga coating layer via the cold spray process and investigated the effect of heat treatment environment on the properties of cold sprayed coating material. Three kinds of heat treatment environments, $5%H_2$+argon, pure argon, and vacuum were used in this study. Annealing treatments were conducted at $200{\sim}800^{\circ}C$/1 hr. With the cold sprayed coating layer, pure ${\alpha}$-Cu and small amounts of $Ga_2O_3$ were detected in the XRD, EDS, EPMA analyses. Porosity significantly decreased and hardness also decreased with increasing annealing temperature. The inhomogeneous dendritic microstructure of cold sprayed coating material changed to the homogeneous and dense one (microstructural evolution) with annealing heat treatment. Oxides near the interface of particles could be reduced by heat treatment especially in vacuum and argon environments. Vacuum environment during heat treatment was suggested to be most effective one to improve the densification and purification properties of cold sprayed Cu-15 at.%Ga coating material.

• 한국인터넷방송통신학회논문지
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• 제19권6호
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• pp.79-85
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• 2019

최근 소형 레이더는 한번의 타격으로 표적의 시스템을 무능화시키기 위해 높은 거리해상도를 갖는 소형 밀리미터파 레이더 개발을 요구한다. 높은 거리해상도를 갖는 소형 밀리미터파 레이더가 표적을 획득하고, 추적하기 위해서는 대용량의 데이터를 실시간으로 처리해야한다. 본 논문에서는 소형 밀리미터파 레이더에서 요구하는 대용량의 데이터를 실시간으로 처리하기 위한 실시간 데이터 전처리 방법을 정리하였다. 또한 실시간 데이터 전처리 방법으로 제시한 디지털 IF(Intermediate Frequency) 수신기, Window처리, DFT(Discrete Fourier Transform)를 FPGA (Field Programmable Gate Array)를 활용하여 구현하였다. 마지막으로 구현한 실시간 데이터 전처리 모듈은 소형 밀리미터파 레이더를 위한 신호처리기에 적용하여 실시간 데이터 전처리 기능과 관련된 성능시험으로 검증하였다.

• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.2037-2043
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• 2017

The surface protein hemagglutinin (HA) mediates the attachment of influenza virus to host cells containing sialic acid and thus facilitates viral infection. Therefore, HA is considered as a good target for the development of diagnostic tools for influenza virus. Previously, we reported the isolation of single-stranded aptamers that can distinguish influenza subtype H1 from H5. In this study, we describe a method for the selective electrical detection of H1 using the isolated aptamer as a molecular probe. After immobilization of the aptamer on Si wafer, enzyme-linked immunosorbent assay (ELISA) and field emission scanning electron microscopy (FE-SEM) showed that the immobilized aptamer bound specifically to the H1 subtype but not to the H5 subtype. Assessment by cyclic voltammetry (CV) also demonstrated that the immobilized aptamer on the indium thin oxide-coated surface was specifically bound to the H1 subtype only, which was consistent with the ELISA and FE-SEM results. Further measurement of CV using various amounts of H1 subtype provided the detection limit of the immobilized aptamer, which showed that a nanomolar scale of target protein was sufficient to produce the signal. These results indicated that the selected aptamer can be an effective probe for distinguishing the subtypes of influenza viruses by monitoring current changes.

• 한국식품영양학회지
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• 제26권1호
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• pp.44-50
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• 2013

Quantitative analyses of naturally occurring methanol were performed for the alcoholic beverages commonly consumed in Jecheon, Chungbuk province, South Korea. The headspace analysis method was optimized for the low and high alcoholic beverages. The external standard method was applied due to the overlapping of 2-propanol and 2-butanol (the internal standard candidates) with target sample matrix peaks. The target samples were selected based on the retail sales amounts of alcoholic beverages in the largest retailer food-mart chain, Jecheon, Chungbuk province, South Korea. There was no sample containing methanol over 0.5 $mg/m{\ell}$, the Korean maximum level of methanol in alcoholic beverages (1.0 $mg/m{\ell}$ for fruit originated liquor etc). The total exposure amount of methanol via alcoholic beverages was estimated based on the daily alcohol consumption of 40 g. The hazard indices calculated by methanol RfD 0.5 mg/kg bw day (US EPA) and ADI 20 mg/kg bw day (proposed by Lachenmeier etc.) were 0.301 and 0.008, respectively. As with the hazard index, aggregate exposures below a HI of 1.0 will likely not result in adverse noncancer health effects over a lifetime of exposure. Then the methanol exposure via the alcoholic liquours might not hazard to Jecheon citizen.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2006년도 학술대회
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• pp.257-260
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• 2006

In Video streaming environment, we must consider terminal and network characteristics, such as display resolution, frame rate, computational resource, network bandwidth, etc. The JVT (Joint Video Team) by ISO/IEC MPEG and ITU-TVCEG is currently standardizing Scalable Video Coding (SVC). This can represent video bitstreams in different sealable layers for flexible adaptation to terminal and network characteristics. This characteristic is very useful in video streaming applications. One fully scalable video can be extracted with specific target spatial resolution, temporal frame rate and quality level to match the requirements of terminals and networks. Besides, the extraction process is fast and consumes little computational resource, so it is possible to extract the partial video bitstream online to accommodate with changing network conditions etc. With all the advantages of SVC, we design and implement a network-adaptive SVC streaming system with an SVC extractor and a streamer to extract appropriate amounts of bitstreams to meet the required target bitrates and spatial resolutions. The proposed SVC extraction is designed to allow for flexible switching from layer to layer in SVC bitstreams online to cope with the change in network bandwidth. The extraction is made in every GOP unit. We present the implementation of our SVC streaming system with experimental results.

• 한국전기전자재료학회논문지
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• 제16권3호
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• pp.186-189
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• 2003

The role of excess Pb about the crystallization behavior and electrical properties in b(Zr$\sub$0.52/Ti$\sub$0.48/)O3(PZT) thin films has not been precisely defined. In this work, the effect of excess Pb content on the ferroelectric properties of these films was investigated. To analyze the effect, PZT films containing various amounts of excess Pb were Prepared. PZT thin films were deposited on the Pt/Ti bottom electrode by rf magnetron sputtering method and then they were crystallized by rapid thermal annealing (RTA). The experiment showed that all PZT films indicated perovskite polycrystalline structure with preferred orientation (111) and no pyrochlore phase was observed. As higher excess Pb was included, the films showed that value of leakage current shift from 2.03${\times}$10$\^$-6/ to 6.63 ${\times}$ 10$\^$-8/A/cm$^2$ at 100kV/cm, and value of remanent polarization shift from 8.587 ${\mu}$C /cm$^2$ to 4.256 ${\mu}$C/ cm$^2$. Electrical properties of PZT thin film affected by Pb excess content of target were explained to be caused of defect among space charges and defect grain boundaries.