• Journal of Environmental Science International
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• v.14 no.1
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• pp.53-60
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• 2005

The concentrations of volatile organic compounds(VOCs) in the ambient air were measured at various point(Source, source boundary) in Seongseo industrial complex during May to November 2003. Air samples were collected in Silcocan canister $(1{\ell},\;6{\ell})$ and analyzed using a cryogenic preconcentration system and GC/MSD. We identified 37 species by the US EPA(TO-14 method). The result showed a variety distribution of the con­centration, Higher concentrations of BTX, Styrene, 1,3,5-Trimethylbenzene, 1,2,4-Trimethylbenzene were observed at the sampling sites. They seemed to be emitted from the facility of wastewater treatment, reaction tank of chemistry factory and facility of Tenter. The concentrations of VOCs contents in Seongseo industrial complex were generally higher than those in Yeosu complex and Ulsan complex, although those were similar in Sihwa­Banwol complex.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1684-1689
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• 2003

Dielectric Barrier Discharges (DBD) in oxygen and air are well established for the production of large quantities of ozone and are more recently being applied to a wider range of after treatment processes for HAPs(Hazardous Air Pollutants). The potential use as a charger for particle collection are not well known. In this work, we measured charge distribution of nanometer or submicron sized particles passing through the dielectric barrier discharge reactor. The bipolar charge characteristics of particles passing DBD reactor were investigated. Fluorometric method using uranine particles and a fluorometer was employed to examine the bipolar charging characteristics of the charged particles by DBD reactor. Finally, the charge distributions of particles were determined from the electrical mobility classification using DMA.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1435-1440
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• 2003

Although Dielectric Barrier Discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs(Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by electrostatic precipitator(ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl($20{\sim}100$ nm) and DOS($50{\sim}800$ nm) were generated by tube furnace and atomizer, respectively. For experimental conditions of 60 Hz, 11 kV, and 60 lpm, the particle collection efficiency for the hybrid system comprising DBD charger and ESP was over 85 %, based on the number of particles captured.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.237-238
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• 2003

대기오염물질 중 수은화합물질은 생태계와 인간에게 치명적인 독성과 생물농축의 특성 때문에 유해한 물질로 관리되어왔으며, 1990년 미국의 Clean Air Act Amendment(CAAA)의 188개의 대기오염물질대기오염물질(HAPs) 중의 하나이고, 국내에서도 25종의 특정대기유해물질 중의 하나로 관리되고 있는 물질이다. 미국 EPA의 보고서에 따르면, 수은화합물의 주요 배출원은 석탄 화력발전소를 비롯한 도시폐기물소각로, 유해폐기물소각로, 병원폐기물소각로 등의 연소설비가 미국 전체 연간 수은배출량의 약 87％를 차지하는 것으로 나타나 주요 배출시설에 대한 관리가 요구되는 것으로 나타났다(US EPA 1997,1998). (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.147-148
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• 2003

미국을 중심으로 HAPs(Hazardous Air Pollutants: 특정대기유해물질)의 유해성이 확인되면서 TRI(Toxics Release Inventory: 유해화학물질 배출공개제도)를 제도화하여 배출 원 관리를 통해 간접적으로 배출량을 줄이는 한편, 직접적으로는 규제 기준을 마련하여 저감 기술개발을 유도하고 있다. 특히 HAPs에 포함된 물질들 가운데 수은은 환경에서 메칠수은으로 변하여 유독성이 한층 높아지고, 먹이 연쇄과정을 통해 농축되어 가장 관리가 시급히 요구되는 물질로 대두되었다. 이에 따라 미국에서는 의회를 중심으로 배출 규제에 대한 일정을 확정하고, 적정한 규제농도가 정해지는 대로 이를 시행할 예정으로 있다. (중략)

• ETRI Journal
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• v.24 no.3
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• pp.197-204
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• 2002

This paper presents the results of the numerical simulation of a multibeam active phased array antenna for a High Altitude Platform Station (HAPS). The simulation takes into account the random errors caused by the non-identity of the array elements and the inaccuracy of the antenna calibration. The results of our statistical simulation show that the strict requirements on the sidelobe envelope for HAPSs can be met when the amplitude and phase distribution errors are minor, a condition which may be achieved by using digital beamforming.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1261-1266
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• 2004

Dielectric Barrier Discharge (DBD) in air, which has been established for the production of large quantities of ozone, is more recently being applied to a wider range of aftertreatment processes for HAPs (Hazardous Air Pollutants). Although DBD has high electron density and energy, its potential use as precharging nano and submicron particles are not well known. In this work, we measured I-V characteristics of DBD and estimated collection efficiency of the particles by DBD type 2-stage ESP. To examine the particle collection with various applied voltage waveforms of DBD for nano and submicron sized, bimodal particles were generated by a electrical tube furnace and an atomizer.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.73-74
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• 2018

This paper presents the incorporation of still-alive access points (SAPs) and helper access points (HAPs) that can be utilized as anchor nodes for position estimation of a First Responders (FRs) for rapidly deployable Emergency Communication Systems (ECS) in disaster recovery. In addition, the localization environment has is formulated and initially examines the use of a distributed Gauss-Newton algorithm (GNA) as optimization technizue. A simulation has been conducted and compared with the commonly used trilateration approach in position estimation.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.71-82
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• 2024

This paper proposes a new communication system for e-learning applications to mitigate the negative impacts of COVID-19 where the online massive demands impact the current commu-nications systems infrastructures and capabilities. The proposed system utilizes high-altitude platforms (HAPs) for fast and efficient connectivity provision to bridge the communication in-frastructure gap in the current pandemic. The system model is investigated, and its performance is analyzed using adaptive antenna arrays to achieve high quality and high transmission data rates at the student premises. In addition, the single beam and multibeam HAP radio coverage scenarios are examined using tapered uniform concentric circular arrays to achieve feasible communication link requirements.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.22-35
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• 2016

In this study CALPUFF modeling was performed to establish a correlation between regions of frequent civil odor complaints near Gumi national industrial complex and odor-emission facilities of synthetic fiber manufacturers in the same area as main acetaldehyde-emission point sources. As a result of the CALPUFF modeling, the maximum concentration of acetaldehyde in Gumi national industrial complex was reduced from O ($10^{-5}g/m^3$) to O ($10^{-6}g/m^3$) upon improving emission facilities of T company so that the maximum concentrations of acetaldehyde frequently appeared in complex 3. In addition, the predicted range of the maximum acetaldehyde concentration in Gumi national industrial complex was also improved in comparison with that prior to improving emission facilities of T company. These maximum concentrations of acetaldehyde obtained to estimate the expected contribution of total acetaldehyde point source by CALPUFF modeling showed the similar values to those measured in 'HAPs investigation in the region of Gumi-Daegu' and were consistent to the trend of civil odor complaints. Therefore, the expected contribution of total acetaldehyde point source was validated. The relative contribution of T company upon improving its emission facilities was predicted to be lowered by more than factor of two, compared to that prior to improving its emission facilities. To the contrary, the relative contribution of W company upon improving emission facilities of T company was predicted to be increased by more than factor of two, compared to that prior to improving emission facilities of T company. This indicates that the contribution of aldehyde point sources of W company was relatively increased upon improving emission facilities of T company.