• 한국환경과학회지
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• 제2권3호
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• pp.207-216
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• 1993

The concentrations of $SO_2$ and $SO_3$ were measured to estimate a new developed long time exposure $SO_2$ sampler at Onsan industrial area considering the meteorological factors from June to October, 1992. The mean concentration of $SO_3$ by $PbO_2$ method was 0.924 mg $SO_3 / 10cm^2$ $PbO_2$/day and their high values were shown in the center of the industrial area, which show potential pollution due to the increase of industrial activities and micrometeorological factors in and around the sites. As a result of statistical correlation between $SO_2$ concentration by new sampling method and $SO_3$ concentration by $PbO_2$ method in July and August, 1992, correlation coefficients were high (r=0.87, 0.91) and shown more than 0.83 value in the high concentration data set, which was arbitrarily divided into 7~10${\mu}l$$SO_2$ concentration in an attempt to further investigate these relationships. Therefore, use of new developed long time exposure TEX>$SO_2$ sampler is good for TEX>$SO_2$ measurement and valuable for estimation of air quality in the urban and industrial area. Key Words : a new developed long time exposure TEX>$SO_2$ sampler, correlation coefficients, high, $SO_2$ measurement, estimation of air Quality.

• 한국대기환경학회지
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• 제12권5호
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• pp.587-591
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• 1996

An intercomparison experiment was implemented to assess the uncertainties and precisions om atmospheric SO$_{2}$ measurement techiques including a pulsed fluorescence (P-F), a diffusion-scrubber /ion chromatography (D-I), and a mist-chamber/ion chromatography (M-I). Each of those three techniques was investigated by researchers at Seoul National University, Yonsei University, and Hankuk University of Foreign Studies, respectively. The concentrations of atmospheric SO$_{2}$ were determined concurrently using three independent measurement techniques at the Seoul National University campus, Korea during Nov.22 to Dec.2, 1995. While the results from the P-F and D-I techinques showed the very close agreements (within +-5%) throughout the experiment period, M-I technique showed systematically smaller values (up to 30%) than the other two techniques. Although sources of larger discrepancy between different techniques were mot identified, the lower SO$_{2}$ values of the M-I method may be related to the errors associated with sample collection effciency, mass flow rate measurements, and standardization of ion chromatography.

• 청정기술
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• 제26권4호
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• pp.293-303
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• 2020

세계보건기구에 따르면 대기오염은 건강에 대한 주요 위험원으로 대기오염으로 인해 매년 약 700만 명의 조기 사망이 발생하고 있다. 이산화황(SO2)은 대표적인 대기오염물질로 황 성분이 포함된 연료의 연소에서 다량 발생한다. SO2 발생량을 감소시키기 위해서는 대형 연소 환경에서 이를 실시간으로 정밀하게 측정하고 측정 값을 바탕으로 저감 설비를 최적화하는 과정이 필요하다. 이 논문에서는 미세먼지 전구물질인 SO2의 농도를 측정하기 위해 파장 가변형 다이오드 레이저 흡수 분광법 중 파장 변조 분광법을 이용하였다. 광원으로는 7.6 ㎛ 양자 폭포 레이저를 사용하였고 7623.7 ~ 7626.0 nm 사이의 64개 다중 광흡수선으로 SO2 농도 측정이 가능함을 증명하였다. 실험은 1 atm, 296 K에서 28, 76 m multi-pass cell을 사용하여 수행되었다. SO2 농도는 고농도(1000 ~ 5000 ppm)와 저농도(10 ppm 이하)로 두 종류로 실험 하였다. 추가적으로 가스 셀 외에 레이저가 지나가는 경로에 질소를 채워 대기 중의 H2O가 SO2 측정에 미치는 영향을 확인하였다. SO2는 3 ppm까지 측정하였고 측정된 SO2 농도는 전기 화학식 센서와 NDIR 센서 측정 결과와 비교되었다.

• 한국산업융합학회 논문집
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• 제25권2_2호
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• pp.299-307
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• 2022

Wireless earphones, along with smart devices, are the most sought-after products by consumers. Compared to general earphones, wireless earphones do not have twisted wires and are easy to use, so various types of products are currently on the market. However, information on quality is somewhat lacking, so consumers tend to purchase products according to brand awareness, and manufacturers are delivering information to consumers using different standards for each product because there is no standard for quality control. In particular, the playback time of wireless earphones is a factor that directly affects consumers' purchases, so a standard measurement method is needed to properly measure it. In this paper, we present a method for measuring the audio playback time of wireless earphones derived from domestic wireless earphone status survey, commercial product measurement test, and research analysis, and a developed standard measurement method. In addition, this paper proposes a measurement result reporting format to provide accurate information to consumers and induce a fair competitive environment for each product to manufacturers.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.49-52
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• 2001

Moire topography method is a well-known non-contacting 3-D measurement method. Recently, the automatic 3-D measurement by moire topography has been required since the method was frequently applied to the engineering and medical fields. 3-D measurement using projection moire topogrphy is very attractive because of it s high measuring speed and high sensitivity. In this paper, using two-wavelength method of projection moire topography tested to measuring object with the $2\pi$-ambiguity problem. Experimental results prove that the proposed scheme is capable of finding absolute fringe orders, so that the $2\pi$-ambiguity problem can be effectively overcome so as to treat large step discontinuities in measured objects.

• 한국정밀공학회지
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• 제9권1호
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• pp.82-95
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• 1992

There is the high interest for sensing of tool wear with the aim of controlling machine tools productivity from the point of view of qualitity. Difficulties in this measurement are also known. This study is on the development of measurement setup for crater wear by CCD image inturning. In this study, the crater wear measurement system consists of the He-Ne gas laser, diffraction grating. CCD camera, noise filter, slit, microcomputer, diverging lens, converging lens and so on. He-Ne laser beam passes through a diverging lens and a diffraction grating is positioned properly. A converging lens focuses so that the interference fringes can be obtained on the crater wear. Performance test revealed that the developed image technique provides precise, absolute tool-wear quantification and reduces human measurement errors. The results obtained are as follows 1. The digitizing of one image requires less than 2ses. 2. It can give detailed information on crater wear with limited times and errors 3. All parameters required by specification are easily obtained for several points of the cutting edge.

• 한국광학회:학술대회논문집
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• 한국광학회 1996년도 Advance Program of 13th optics andquantum Electronics conference, 1996제13 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.91-91
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• 1996

• 한국정밀공학회지
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• 제22권7호
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• pp.88-93
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• 2005

$Moir\acute{e}$ topography method is a well-known non-contacting 3-D measurement method. Recently, the automatic 3-D measurement by $Moir\acute{e}$ topography has been required, since the method was frequently applied to the engineering and medical fields. The 3-D measurement using projection $Moir\acute{e}$ topography is very attractive because of its high measuring speed and high sensitivity. In this paper, using two-wavelength method of projection $Moir\acute{e}$ topography was tested to measuring object with $2\pi-ambiguity$ problems. The experimental results prove that the proposed scheme is capable of finding absolute fringe orders, so that the $2\pi-ambiguity$ problems can be effectively overcome so as to treat large step discontinuities in measured objects.

• 한국대기환경학회지
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• 제13권5호
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• pp.361-369
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• 1997

In order to investigate the abundance and transboundary fluxes of air pollutants over the Yellow Sea, airborne measurements were made aboard the SF-600 aircraft (Pan-Asia Engineering) in March, 1996. The data presented in this paper are preliminary results and airborne experiment will be carried out until 1999. The vertical profile of relevant meteorological parameters such as temperature, water vapor, wind direction and wind speed were also observed at Taean. Mixing layer height was about 1000~1100m during the flights. The SO$_2$ and NO$_{x}$ concentrations were 3~6 ppb and 5~7 ppb below 1000 m, within 1 ppb and 3~5 ppb at 1000~2000m, respectively. Backward trajectory analyses were also carried out. A mathematical method by Lelieveld et al.(1989) was used to estimate the flux of air pollutants through the planetary boundary layer of Yellow Sea area. Transboundary fluxes were calculated using the measurement results with respect to the pollutants concentration, depth of the planetary boundary layer, wind speed and wind direction. The estimated transboundary flux of SO$_2$through the western boundary of Korea was about 39~42 tons/hour.r.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2004년도 추계학술대회 논문집
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• pp.298-299
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• 2004