• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.940-941
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• 2015

LCD (liquid crystal display) industry is needed to goods of high reliability and is interested in products without harmful material. In this experiment, we made the LED backlight unit for Automotive-navigation. And for making this backlight unit we used to eight side emitting type white LEDs with 1W high power of the lumileds company. We could know that this backlight unit releases to 6500 nit in 14W power consumption and start up voltage time is under the15ms in the ambient temperature $-20^{\circ}C$.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.63-64
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• 2000

본 연구는 대전 1,2공단 지역을 대상으로 22개의 원소를 선정하여 ICP-MS를 이용하여 분석한 농도와 도로변 지역인 충남대학교 정문 지역을 대상으로 31개의 원소를 선정하여 NAA를 이용하여 분석한 농도를 가지고 두 가지의 분석방법에서 공통적으로 분석된 원소들을 통해 대전의 대표적인 공단지역과 도로변 지역의 농도를 비교 평가해 보고자 한다. (중략)

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.4
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• pp.625-625
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• 2018

• Mass Spectrometry Letters
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• v.13 no.2
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• pp.27-34
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• 2022

Atmospheric aerosols have become a major environmental concern because of their adverse effects on human health, air quality, and climate change. Over the last few decades, several mass spectrometry (MS)-based techniques have been developed and applied in the field of atmospheric aerosol research. Particularly, real-time measurement of ambient aerosols using an aerosol mass spectrometer (AMS) has become one of the most powerful tools for aerosol chemistry. This review provides a brief description of AMS and its applications for understanding the physicochemical properties of atmospheric aerosols, as well as its sources and evolution processes.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.437-444
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• 2007

This paper experimentally investigates the effects of oxygen-enriched air (OEA) on the running behaviors of an LPG SI engine during both start/warm-up (SW) and hot idling (HI) stages. The experiments were performed on an air-cooled, single-cylinder, 4-stroke, LPG SI engine with an electronic fuel injection system and an electrically-heated oxygen sensor. OEA containing 23% and 25% oxygen (by volume) was supplied for the experiments. The throttle position was fixed at that of idle condition. A fueling strategy was used as following: the fuel injection pulse width (FIPW) in the first cycle of injection was set 5.05 ms, and 2.6 ms in the subsequent cycles till the achieving of closed-loop control. In closed-loop mode, the FIPW was adjusted by the ECU in terms of the oxygen sensor feedback. Instantaneous engine speed, cylinder pressure, engine-out time-resolved HC, CO and NOx emissions and excess air coefficient (EAC) were measured and compared to the intake air baseline (ambient air, 21% oxygen). The results show that during SW stage, with the increase in the oxygen concentration in the intake air, the EAC of the mixture is much closer to the stoichiometric one and more oxygen is made available for oxidation, which results in evidently-improved combustion. The ignition in the first firing cycle starts earlier and peak pressure and maximum heat release rate both notably increase. The maximum engine speed is elevated and HC and CO emissions are reduced considerably. The percent reductions in HC emissions are about 48% and 68% in CO emissions about 52% and 78%; with 23% and 25% OEA, respectively, compared to ambient air. During HI stage, with OEA, the fuel amount per cycle increases due to closed-loop control, the engine speed rises, and speed stability is improved. The HC emissions notably decrease: about 60% and 80% with 23% and 25% OEA, respectively, compared to ambient air. The CO emissions remain at the same low level as with ambient air. During both SW and HI stages, intake air oxygen enrichment causes the delay of spark timing and the increased NOx emissions.

• Analytical Science and Technology
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• v.14 no.5
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• pp.442-450
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• 2001

In this study, we collected PM10(particulate matter less than $10{\mu}m$) by using a high volume air sampler from March 2000 to September 2000 to investigate the contamination level and the distribution characteristics of heavy metals in the ambient air in Ulsan area. Samples were pretreated by the microwave extraction methods, and heaby metals (Cr, Cu, Zn, Cd, Ni, As, and Pb) were quantified by using and ICP-MS system. The highest PM10 concentrations in the ambient air were $85.6{\mu}g/m^3$ and the aberage value was $37.1{\mu}g/m^3$. The maximum levels of each heavy metal were as follows: $2.5{\mu}g/m^3$ for Fe(Yeocheon-dong), $0.41{\mu}g/m^3$ for Zn(Nammok-2-dong), $0.061{\mu}g/m^3$ for Cd(Yeocheon-dong), $0.20{\mu}g/m^3$ for Pb(Yeocheon-dong), $0.037{\mu}g/m^3$ for Ni(Yeoncheon-dong), $0.88{\mu}g/m^3$ for Cu(Yaeum-dong), $0.042{\mu}g/m^3$ for Cr(Yaeum-dong), and $0.015{\mu}g/m^3$ for As(Onsan). Among concentration of heavy metals, Ni and Zn compounds were highly correlated with a correlation coefficient of 0.87 at Nammok-2-dong.

• Journal of Environmental Science International
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• v.14 no.3
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• pp.351-358
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• 2005

The research in this paper was carried out to examine the BTEX(Benzene, Toluene, Ethylbenzene, Xylene) concentrations in Seongseo Industrial Complex. These compounds are the major constituents, more than $60\%$ in composition of total VOCs, mainly charging in ambient air. BTEX samples were collected from the 38 sites, 10 for the source points and 18 for the boundary sites, and were analyzed by canister-GC/MS. The mean concentrations of BTEX were 33 ppbv for benzene, 214 ppbv for toluene, 89 ppbv for ethyl benzene, 77 ppbv for xylene. Among the BTEX, toluene had the highest concentration in the source points and boundary sites. In the source points, BTEX concentration of incineration facility for hazardous wastewater appeared highly in the range of 220­350 ppbv. BTEX concentrations in source boundary sites appeared in the order of toluene>ethylbenzene>xylene>benzene. As a result of the correlation analysis, the concentration of the source points was related to those of the boundary sites. Correlation of ethylbenzene and xylene was presented to 0.7991(P<0.0 1),\;0.6329(P<0.05) as the correlation coefficient, respectively.

• Analytical Science and Technology
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• v.12 no.4
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• pp.332-340
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• 1999

Homemade cryogenic preconcentration system is constructed to preconcentrate the VOCs in the ambient air collected in canister. Homemade preconcentrator equipped with GC-MS was used for analysis of air sample containing VOCs at ppb level identified in EPA TO-14 method. The system was evaluated for analytical performance by comparison with the results of adsorption tube method widely used in the past, and shows good agreement for concentrations of benzene, toluene, ethylbenzene, and xylenes.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.417-428
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• 1999

The measurement of VOSCs(volatile organic sulfur compounds) in the air is nowadays a very important environmental research field. It is, however, very difficult because the concentration of the VOSC in ambient air is usually very low and the high reactivity makes it difficult to keep in container without loss of recovery. In this study, sampling method with cryogenic preconcentration is evaluated for analysis of atmospheric VOSC such as $CH_3SH,\;CH_3CH_2SH,\;CH_3SCH_3,\;CS_2,\;CH_3SSCH_3,\;CH_3SCH_2SCHA_3,\;and\;C_2H_5SSC_2H_5$ analyzed by GC-MS or GC-FID. Repeatabilities of measurement accompanied with preconcentration for 3-successive runs were in the range of 0.2~1.0% as a relative standard deviation. Stabilities up to 13 days were measured in 6 L canister and 10 L tedlar bag filled with VOSCs in ppb level. Higher stability was observed in tedlar bag as compared to canister with glass coated inner walls, and thiol compounds show dramatic losses in canister within 2~3 days. It is found that recovery over 70% was obtained in a week for all tested VOSCs when the compounds from ambient air matrix were stored in tedlar bag. It is also found that the stabilities of VOSCs are depending on humidity and coexisting compounds in matrix gas due to sample adsorption onto inner surface and reactivity. The results indicate the possibility and limitations of VOSC analysis in ambient air using container sampling method with cryogenic preconcentration.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.1
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• pp.35-44
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• 2000

The winter case of the near-field dilution at the Masan outfalls has been studied by field measurements and CORMIX model simulations. Dilution rates of the wastewater discharge in winter were obtained by a salinity deficit method using the field data observed in the neap tidal period of February, 1999. The observed dilution rates in winter season were found to be very high in the range of 90～130 due to the isopycnal mixing of ambient density compared with the summer range of 30～40 under weak neap tidal currents. The results of CORMIX model simulations also show that the winter dilution rates under a weak ambient current(Ua=6.0ms/s) were increased by 3-fold of the summer dilution rates. However, the difference between two seasons becomes small by 30% under a strong current(Ua=15.5cm/s). This result indicates that the dilution and hydrodynamic mixing process of the effluents are more influenced by ambient crossflow condition than by ambient density stratification at the outfalls site.