• Journal of the Korean Chemical Society
• /
• v.53 no.1
• /
• pp.27-33
• /
• 2009

A sensitive technique for the determination of trace Cd(II) in various real samples after preconcentration onto microcrystalline p-dichlorobenzene loaded with 2-mercaptobenzothiazole was developed. Several experimental conditions such as the pH of the sample solution, the amount of chelating agent 2-mercaptobenzothiazole, the amount of adsorbent p-dichlorobenzene-2-MBT, and the flow rate of sample solution were optimized. The interfering effects of various concomitant ions were investigated. Cu(II) interfered with more seriously than any other ions. However, the interference by Cu(II) could be overcome sufficiently by adjusting tartrate ion concentration to be 0.01M or by controlling the amount of 2-mercaptobenzothiazole contained in 0.20 g p-dichlorobenzene to be 0.12 g. The dynamic range, the correlation coefficient ($R^2$) and the detection limit obtained by this proposed technique were $0.5{\sim}30$ ng $mL^{-1}$, 0.9962, and 0.39 ng $mL^{-1}$, respectively. Thus, good results were obtained by the use of p-dichlorobenze as adsorbent matrix. For validating this proposed technique, the aqueous samples(wastewater, stream water, and reservoir water) and the plastic sample were used. Recovery yields of $93{\sim}104$ % were obtained. By F test, these measured data were not different from ICP-MS data at 95 % confidence level. Based on the results from the experiment, it was found that this proposed technique could be applied to the preconcentration and determination of Cd(II) in various real samples.

• Korean Journal of Optics and Photonics
• /
• v.13 no.4
• /
• pp.363-369
• /
• 2002

We have designed conductive transparent filters using a low-emissivity coating such as [dielectric|Ag|dielectric] for display applications. The design is the repetition of [$TiO_{2}$|Ti|Ag |$TiO_{2}$] to increase the transmittance in the visible and decrease the transmittance in the near IR. The conductive transparent filters are deposited by a radio frequency(RF) magnetron sputtering system. The optical, structural and electrical properties of the filters were investigated and the optical spectra are compared with simulated spectra. The thickness of the deposited Ag films is above 13 ㎚ to increase the conductivity and that of $TiO_{2}$ films is 24 ㎚ to increase the transmittance in the visible range. Ti blockers are employed to prevent the Ag films from being oxidized by an oxygen gas during the reactive sputtering process. Also, it is shown that the thicker Ti film is necessary as the period increases. Finally, a filter with repetition of the basic structure three times shows the better cut-off near infrared(NIR) and the sheet resistance as low as 2Ω/□ which is enough to shield an unnecessary electromagnetic waves for a display panel.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.18 no.5
• /
• pp.724-729
• /
• 2008

This paper presents the calculation of the required bandwidth of common frequency bandwidth applying queueing theory for maximizing the efficiency of frequency resource of WPAN(Wireless Personal Area Network) based Digital acoustic and communication devices. It assumed that LBT device(ZigBee) and FH devices (DCP, RFID and Bluetooth) coexist in the common frequency band for WPAN based Digital acoustic and communication devices. Frequency hopping (FH) and listen before talk (LBT) have been used for interference avoidance in the short range device (SRD). The LBT system transmits data after searching for usable frequency bandwidth in the radio wave environment. However, the FH system transmits data without searching for usable frequency bandwidth. The queuing theory is employed to model the FH and LBT system, respectively. As a result, the throughput for each channel was analyzed by processing the usage frequency and the interval of service time for each channel statistically. When common frequency bandwidth is shared with SRD using 250mW, it was known that about 35 channels were required at the condition of throughput 84%, which was determined with the input condition of Gaussian distribution implying safety communication. Therefore, the common frequency bandwidth is estimated with multiplying the number of channel by the bandwidth per channel. These methodology will be useful for the efficient usage of frequency bandwidth.

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

• Journal of Food Hygiene and Safety
• /
• v.4 no.3
• /
• pp.171-176
• /
• 1989

A rapid, simple method of ELISA was applied for the determination of aflatoxin BI in cereals from Y oungnam districts. Antibodies obtained cross reacted with aflatoxin B2 and to a less extent with other aflatoxin BI analogs. Response range for a typical standard curve was between I and 100 ppb. Fewer interference by spiked methanol-PBSdimethylformamide extracts ofrice was evidenced. Contents of aflatoxin BI from rice (65) and barley (116) were determined by competitive direct enzyme- linked immunosorbent assay as follows. Three out of 65 rices samples were positive. Rice samples of R-IS, R-30, and R-59 represent the aflatoxin B1 levels of $7.5\;\mu\textrm{g}.kg,\;6.0\;\mu\textrm{g}/kg,\;3.5\;\mu\textrm{g}/kg,\;3.3\;\mu\textrm{g}/kg$, respectively, and showed 4.6% aflatoxin BI contamination in rice samples. Meanwhile, four out of 116 barley samples were positive. VB-37 showed the highest aflatoxin Bllevels of $9.6\;\mu\textrm{g}/kg$ and VB-35, VB-15 and VB-54 represent $7.5\;\mu\textrm{g}.kg,\;6.0\;\mu\textrm{g}/kg\;and\;3.6\;\mu\textrm{g}/kg$, respectively, and showed 3.4% aflatoxin B1 contamination in barley samples.

• Korean Journal of Remote Sensing
• /
• v.33 no.6_1
• /
• pp.947-960
• /
• 2017

Soil moisture plays an important role to affect the Earth's radiative energy balance and water cycle. In general, satellite observations are useful for estimating the soil moisture content. Passive microwave satellites have an advantage of direct sensitivity on surface soil moisture. However, their coarse spatial resolutions (10-36 km) are not suitable for regional-scale hydrological applications. Meanwhile, in-situ ground observations of point-based soil moisture content have the disadvantage of spatially discontinuous information. This paper presents an experimental soil moisture retrieval using Sentinel-1 SAR (Synthetic Aperture Radar) with 10m spatial resolution for cropland in South Korea. We developed a soil moisture retrieval algorithm based on the technique of linear regression and SVR (support vector regression) using the ground observations at five in-situ sites and Sentinel-1 SAR data from April to October in 2015-2017 period. Our results showed the polarization dependency on the different soil sensitivities at backscattered signals, but no polarization dependence on the accuracies. No particular seasonal characteristics of the soil moisture retrieval imply that soil moisture is generally more affected by hydro-meteorology and land surface characteristics than by phenological factors. At the narrower range of incidence angles, the relationship between the backscattered signal and soil moisture content was more distinct because the decreasing surface interference increased the retrieval accuracies under the condition of evenly distributed soil moisture (during the raining period or on the paddy field). We had an overall error estimate of RMSE (root mean square error) of approximately 6.5%. Our soil moisture retrieval algorithm will be improved if the effects of surface roughness, geomorphology, and soil properties would be considered in the future works.

• Resources Recycling
• /
• v.20 no.1
• /
• pp.28-36
• /
• 2011

More than 50% of refractory materials generated from high-temperature melting furnace was not carbonized and could be recycled by adopting proper separation process. In the present work, the separation of refractory materials has studied by adopting color sorting technology to promote the recycling of waste refractory. Purity of the refractory materials was obtained with at 97.2%, color temperature of sorter light source 6,500K, which gives less interference of surrounding light source. Purity and separation efficiency were improved as size is setting bigger and lower conveyer belt speed. It is revealed that optimum conditions were color temperature 6,500K, conveyer belt speed 1,000 mm/sec, particle size -20 mm, etc. To improve purity and separation efficiency on below 10mm size, the resolution of should be fixed camera and it narrow recognition range. As a result of the study, color sorting technology could be used for separation of waste refractory materials and will contribute to promote the waste recycling.

• Journal of the Korean Vacuum Society
• /
• v.20 no.5
• /
• pp.361-366
• /
• 2011

An in-situ, real-time monitoring of GaN epilayers grown by low pressure metalorganic chemical vapor deposition system modified for spectral reflectance was performed. Reflectance spectrums from 190~861 nm were observed using p-polarized light with incident angle of $75^{\circ}$. All reflectance spectrums showed interference oscillation caused by multiple reflection within GaN epilayers, and the spectrum from GaN with low crystalline quality showed weak reflectance intensity and much low amplitude of the oscillation because many defects in GaN resulted in light scattering and absorption. Signal variation of reflected light which was selected around strong constructive wavelength range was also observed during $NH_3$ supplying and $NH_3$ cut-off. There was no significant change in signal intensity when $NH_3$ cut-off for 10 sec, but it showed higher intensity when $NH_3$ was cut off for over 30 sec and its intensity kept unchanged. This result indicates that GaN surface was N-terminated during $NH_3$ supplying but Ga-terminated during $NH_3$ cut-off because of high nitrogen equilibrium vapor pressure of GaN, and metallic Ga-terminated surface caused slightly higher reflectance intensity.

• Journal of Pharmaceutical Investigation
• /
• v.32 no.2
• /
• pp.119-125
• /
• 2002

A rapid, selective and reproducible high-performance liquid chromatographic method has been developed for the determination of terazocin in human plasma. Terazocin plus the internal standard, prazocin hydrochloride, were extracted from alkalified plasma with tert-butylmethyl ether, back-extracted into 0.05% phosphoric acid. Fifty ${\mu}l-portions$ of extract were injected onto a octadecylsilane column and eluted with a mixture of acetonitrile, water and triethylamine (30 : 70 : 0.1 v/v, adjusted to pH 5.0 with dilute phosphoric acid) at a flow rate of 1.0 ml/min. The fluorescence intensity of column eluents was monitored at excitation wavelength of 250 nm and emission wavelength of 370 nm. No interference peaks were observed. The practical limit of quantitation was 5 ng/ml for terazocin. The average intraday and interday coefficients of variation were 4.15 and 3.54%, respectively. Also intraday and interday precisions over the range $5{\sim}60\;ng/ml$ were $0.49{\sim}2.92\;and\;0.38{\sim}5.12%$, respectively. The bioequivalence of two terazosin tablets, the $Hytrine^{\circledR}$ (Il Yang Pharmaceutical Co., Ltd.) and the $Teratonin^{\circledR}$ (Sam-A Pharmaceutical Co., Ltd.), was evaluated according to the guideline of Korea Food and Drug Administration (KFDA). Sixteen healthy male volunteers $(24.6{\pm}2.0\;years\;old)$ were divided into two groups and a randomized $2{\times}2$ cross-over study was employed. After one tablet containing 2 mg of terazosin was orally administered, blood was taken at predetermined time intervals and the concentration of terazosin in plasma was determined with a HPLC method using spectrofluorometric detector. AUC was calculated by the linear trapezoidal method. $C_{max}\;and\;T_{max}$ were compiled from the plasma drug concentration-time data. Analysis of variance (ANOVA) was utilized for the statistical analysis of the parameters. The results showed that the differences in $AUC_t,\;C_{max}\;and\;T_{max}$ between the two preparations were 0.21 %, 5.53% and 8.82%, respectively. The powers $(1-{\beta})\;for\;AUC_t,\;C_{max}\;and\;T_{max}$ were >99%, 97.49%, and 33.26%, respectively. Minimum detectable differences $({\Delta},\;%)\;at\;{\alpha}=0.1\;and\;1-{\beta}=0.8$ and the 90% confidence intervals were all less than ${\pm}20%$ except for $T_{max}.\;AUC_t\;and\;C_{max}$ met the criteria of KDFA for bioequivalence, indicating that $Teratonin^{circledR}$ tablets are bioequivalent to $Hytrine^{circledR}$ tablets.

• Journal of the Korean Vacuum Society
• /
• v.21 no.1
• /
• pp.62-68
• /
• 2012

The conversion efficiency of solar cells depending on incident angle of light is important for building-integrated photovoltaics (BIPV) applications. The quantum efficiency is the ratio of the number of charge carriers collected by the solar cell to the number of photons of a given energy shining on the solar cell. The analysis of angle dependence of quantum efficiencies give more information upon the variation of power output of a solar cell by the incident angle of light. The variations in power output of solar cells with increasing angle of incidence is different for the type of cell structures. In this study we present the results of the quantum efficiency measurement of single-crystalline silicon solar cells and a-Si:H thin-film solar cells with the angle of incidence of light. As a result, as the angle of incidence increases in single-crystalline silicon solar cells, quantum efficiency at all wavelength (300~1,100 nm) of light were reduced. But in case of a-Si:H thin-film solar cells, quantum efficiency was increased or maintained at the angle of incidence from 0 degree to about 40 degrees and dramatically decrease at more than 40 degrees in the range of visible light. This results of quantum efficiency with increasing incident angle were caused by haze and interference effects in thin-film structure. Thus, the structural optimization considering incident angle dependence of solar cells is expected to benefit BIPV.