• Journal of Food Hygiene and Safety
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• v.7 no.1
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• pp.45-48
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• 1992

In Food revolution of Korea, colorimetries or a titration methods are introduced for the analysis of alcoholic liquors. But, these wet analyses have disadvantages such as individual errors, long process time, and sometimes tedious pretreatments. In the process of making alcoholic liquors, fusel oils are produced as by products. Five main fusel components that could be produced are 2-propanol, n-propanol, iso-butanol, n-butanol, and isoamyl alcohol. Also acetaldehyde and methanol could be produced as by-products of ethanol. With using capillary FFAP column in GC or GC/MSD, we analysed these five fusel components as well as internal standard (acetonitrile) including methanol, acetaldehyde and ethanol simultaneously. We obtained excellent mass spectra as qualitative data of all species. We also took excellent quantitative data with GC by using the internal standard method.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.184-188
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• 1989

This paper presents a fast realistic method based on a P-Q decoupled linearized model for contingency analysis. This method involves new idea to correct the errors caused by neglecting the resistance of transmission lines and/or by linearizing the model. The idea is to use fast correction method of errors by the principle of superposition for compensating these errors. Results demonstrating the effectiveness of the method on 25-bus model system and IEEE30-model system are presented

• Analytical Science and Technology
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• v.13 no.4
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• pp.403-411
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• 2000

This study described a method of thermoluminescence dating of pottery shards using subtraction method. TL measurement was achieved using two different types of samples prepared by quartz inclusion method and fine-grain technique. Fine grains (size range: $5-10{\mu}m$) were separated by suspending grounded pottery samples into acetone solution and sedimentation quantitatively. In quartz inclusion method quartz grains in the size range of 90 to $125{\mu}m$ diameter were obtained by extracting the quartz crystals embed in the pottery shards and etching them with 1.0 M HF solutions. The archaeological dose of both the quartz and fine grains was determined from the dose calibration curves obtained from sequential irradiation of $^{137}Cs$ gamma and $^{241}Am$ alpha source to the samples and TL measurement of natural samples, in which the alpha dose of 4.60 Gy for the Packjae pottery was obtained using subtraction method. Annual alpha dose rates ($3.05{\pm}0.11$ mGy/yr.) were determined by the analysis of U, Th contents in the pottery shards and evaluation of the values with Bell's equation. Dividing the alpha dose accumulated in the pottery shards by the annual alpha dose rate, we found age of approximately $1508{\pm}80$ years B.P. (AD. ca. 492 yr.) for the Packjae pottery. It matches well with the archeological age estimate (middle of 5th century) within 10 percent uncertainty and thereby conforms the age of the pottery sample.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.164-175
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• 2019

Installation of digital tachograph, black box, and ADAS have been enforced to commercial vehicles for preventing violent driving and accidents by the Traffic Safety Act in Korea. Nevertheless, the damage caused by road hazards has increased 1.5 times in 2016 compared to 2013. So, developing new technologies that can identify road hazard using the sensors installed in commercial vehicles are conducting by the Ministry of Land, Infrastructure and Transport. As a part of the technologies, this research analyze the error range of GPS installed in commercial vehicles that vary according to the driving speed. As a result, the average error was 9.72m at the driving speed of 100km/h, and the error was 2.1 times larger than the average error of 4.69m at the driving speed of 40km/h. The event point proper integration/separation range(m) was analyzed to be 20m with a recognition rate of 90% or more at the same point regardless of driving speed. The results of this research can be used as basic data for improving the accuracy of location-based data would be collected using commercial vehicles.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.1
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• pp.19-27
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• 2007

Combined method of extraction chromatography and liquid scintillation analysis was established for determinating $^{55}Fe\;and\;^{63}Ni$ radioactivity in solid samples. Activated concrete wastes generated from dismantling KRR-2 were analysed. The sequential separation including precipitation and extraction chromatography resulted in the above 90% chemical recoveries of Fe. Above 62% recoveries of Ni were obtained by this procedure exception to 43.6 and 46.5% recoveries. The seperation and counting procedure was also confirmed with spiked samples of known quantity. The measured and spiked quantity were agreed with the 3.7% and 0.7% variations in the $^{55}Fe\;and\;^{63}Ni$ experiments, respectively. The radioactivities of $^{55}Fe$ in the dismantled concretes are shown from below MDA to maximum 362 Bq/g. The radioactivities of $^{63}Ni$ in all concrete samples are below MDA. The $^{63}Ni$ doesn't exist in dismantled concretes from KRR-2. The radioactivity of $^{55}Fe$ is decreased rapidly as the sampling depth is increased from the concrete surface.

• Geophysics and Geophysical Exploration
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• v.12 no.3
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• pp.246-254
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• 2009

We developed a novel polarization filter to separate linearly polarized waves from elliptically polarized waves in an infinite homogeneous medium and at the free surface using methods of multicomponent complex trace analysis. Sensitivity to filter parameters were examined using synthetic data simulating particle motions in a homogeneous medium. For known amplitude ratios of horizontal-to-vertical components of P and Rayleigh waves $C_L$ and $C_R$, respectively, the polarization filter precisely removes Rayleigh waves. Errors in the vertical and horizontal components of the filtered results increase with the ratio $C_R$/$C_L$ and the product $C_R$.$C_L$, respectively. The vertical component errors also increase rapidly as the ratios of applied-to-modeled values of $C_L$ and $C_R$ ($C_L'$/$C_L$ and $C_R'$/$C_R$) decrease, and are sensitive to $C_R'$/$C_R$ and $C_L'$/$C_L$ for small and large incidence angles, respectively. Errors of the filter are exactly the same for shear waves when the incidence angle is the supplementary of P-wave incidence angle.

• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.324-334
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• 2024

The Wavefront Curvature Ranging (WCR) is an estimation method for a source range from the wavefront curvature of acoustic waves. The conventional method uses trigonometry to estimate the source range by assuming the sound speed as a constant. Because of this assumption, range error occurs in the ocean environment where the bottom reflection is clearly separated. In order to reduce the range error, Matched Wavefront Curvature Ranging (MWCR) was proposed applying the sound speed structure in the ocean environment and Maximum Likelihood Estimation (MLE). The range error was reduced in the results of the simulation on the proposed method. In the future, this method will be applicable to the sonar system if the reliability of ranging is confirmed by measured signal.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.389-400
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• 2011

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of phenothrin and silafluofen, known as synthetic pyrethroids, in agricultural commodities. Insecticide residues were extracted with acetone from representative samples of four crops which comprised rice, apple, pepper and cabbage. The extract was purified serially by liquid-liquid partition and Florisil column chromatography. For rice and pepper samples, acetonitrile/n-hexane partition was additionally adopted to remove nonpolar interferences. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate two phenothrin isomers and silafluofen from sample co-extractives. Intact parent compounds were sensitively detected by ultraviolet absorption at 226 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine phenothrin and silafluofen residues at 0.02 and 0.01 mg/kg, respectively. Mean recoveries of phenothrin and silafluofen from four crop samples fortified at three levels in triplicate were in the range of 82.4~109.8% and 83.7~109.8%, respectively. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types and spiking levels. A selected-ion monitoring (SIM) LC/mass spectrometry (MS) with electrospray ionization was provided to confirm the suspected residue of phenothrin, even though no sufficient ionization of silafluofen was obtained. Both phenothrin and silafluofen could be successfully confirmed by gas chromatography/MS SIM with electron impact at 70 eV. The proposed method is sensitive, repeatable and rapid enough to apply to officially routine inspection of agricultural products.

• Journal of the Korean Geophysical Society
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• v.4 no.2
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• pp.87-93
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• 2001

The roof tiles excavated from the mountain fortress at Namsan-ri Seocheon-gun in Chungnam province were dated by using SAR protocol, Sample preparation was done with the quartz exclusion method. The paleodoses from 6 kinds of roof tiles were obtained from OSL measurements and the does rates of the soil around the excavated roof tiles and the tile themselves were measured from ICP/MS and ICP/AES with the conversion table. From the evaluated paleodose and the dose rate, the age of the roof tiles were determined to be from(733 ± 50)AD to (1160 ± 50)AD and the error was less than 10%.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.91-94
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• 2002

음성인식 시스템의 실용화를 위해서 우선적으로 해결되어야 될 문제중 하나로 잡음환경하에서의 끝점검출을 들 수 있다. 잡음이 존재하지 않는 환경에서는 기존의 에너지 파라미터만으로도 어느정도 신뢰성있는 끝점 구간을 검출할 수 있으나 도심 소음과 같은 실제 잡음환경하에서는 대부분 좋지 않은 결과를 보인다. 본 논문에서는 도심환경의 배경잡음을 제거하는 방법으로 입력되는 음성에 대하여 주변소음에 의해 손상된 음성스펙트럼의 크기 성분만을 제거하는 전처리 기법인 Bark scale에 기반한 스펙트럼 차감법을 사용하고, 인간의 청각특성을 고려하여 음성의 주파수 대역을 3개의 대역으로 분리한 후, 대역별로 세밀한 에너지 문턱치값을 설정하여 음성의 끝점을 탐색하는 방법을 제안한다. 제안한 방법의 유효성을 확인하기 위해 실제 사무실 및 지하철역 등의 잡음환경하에서 녹음된 데이터베이스를 이용하여 끝점검출을 수행한 결과 기존의 에너지와 영교차율을 이용한 방법에 비해 평균 $46\%$의 오차율 감소와 대역에너지만을 사용한 경우에 비해 평균 $17\%$의 오차율 감소를 나타내어 제안한 방법의 유효성을 확인할 수 있었다.