• 한국환경과학회지
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• 제10권3호
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• pp.209-216
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• 2001

Dustfall particles were collected by the modified American dust jar (wide inlet bottle type) at 6 sampling sites in Pusan area from March, 1999 to February, 2000. Thirteen chemical species (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Si, and Zn) were analyzed by AAS and ICP. The purposes of this study were to estimate qualitatively various bulk deposition flux of dustfall and insoluble components by applying regional and seasonal distribution. Dustfall amount of regional variations were found in order of coastal zone, industrial zone, commercial zone, agricultural zone and residential zone, and seasonal total dustfall had higher concentrations during spring for 6.741 ton/${km}^2$/season, lower concentrations during summer for 1.989 ton/${km}^2$/season, and annual total concentration was 17.742 ton/${km}^2$/year. The regional distributions of enrichment factor show well-defined anthropogenic metals (Cd, Cu, Pb, and Zn) at industrial and agricultural zone, and contribution rate of soil particles were found in order of summer, fall, winter and spring. Factor loading effects of chemical composition of dustfall were found in order of road traffic emission source and combustion processed source, industrial activity source, soil source and marine source.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2141-2152
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• 2024

Tungsten is the most promising plasma facing material for fusion reactors. Rolled W-Y₂(Zr)O₃ bulk material has been successfully produced in this study for future fusion engineering applications. The introduction of Zr is conducive to the refinement of the second phase particles. Nano-sized Y-Zr-O particles are observed in the powder and bulk samples. Related results show that the Y-Zr-O particle dispersion distribution improves the heat load resistance of W-Y₂(Zr)O₃ composite material. For four-point bend experiments in the same sampling direction, the DBTT of W-Y₂(Zr)O₃ composite materials is lower compared to the pure tungsten. For the same material, the DBTT of the material was selected for testing along the RD direction is lower compared to the material was selected for testing along the TD direction. Findings of this study provide suggestions for the subsequent industrial preparation of nanoscale particle-doped tungsten materials.

• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1457-1469
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• 2002

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an Sl engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it Is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swir and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.

• 환경위생공학
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• 제20권3호
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• pp.17-26
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• 2005

Many researches were focused on the data which obtained from chemical bulk analysis. It is difficult to evaluate source contribution by wet type chemical bulk analysis. In this study, we have reviewed the characterization of individual particle for source identification. We analyzed by SEM/EDX methods. We have obtained average geometric particle diameter measured by optical diameter which were resulted from SEM/EDX image scan, representative physical diameter of individual particle was $3.38\;{\mu}m\;in\;A,\;3.67\;{\mu}m\;in\;B$. In the result of image analysis at each spots particles, both samples non-sphere shapes, C-rich particles. In consequence of chemical analysis of individual particle, each sampling sites some elements.

• 응용통계연구
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• 제24권3호
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• pp.465-475
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• 2011

본 연구에서는 공장용지 면적을 예측하기 위한 통계적 추정을 다루었다. 공장용지에 대해서는 1981년부터 2003년까지 자료가 존재하며, 2004년 이후에는 공장용지보다 좁은 개념인 산업단지 면적에 대한 조사 자료만 존재한다. 한국산업단지공단에서는 2009년 10월 표본조사를 실시하여 당해의 공장용지 면적을 추정하였으며, 동 조사 시 향후 5개년의 공장용지면적에 대한 수요를 조사한 바 있다. 본 연구에서는 과거 절단된 자료를 여러 통계모형을 사용하여 적절히 대체할 수 있는 수요예측모형을 도출하고, 표본조사에 의한 추정치와 통계적 모형에 의한 대체값들을 융합하는 평활기법으로 향후 공장용지 수요를 예측하는 방법을 다루었다.

• 한국광학회:학술대회논문집
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• 한국광학회 2002년도 하계학술발표회
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• pp.98-99
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• 2002

대표적인 II-VI족 극성 반도체 결정인 ZnTe[001]와 ZnCdTe MQW에서 시료의 에너지 띠보다 낮은 에너지의 펨토초 티타늄 사파이어 레이저를 이용하여 결맞는 포논을 발생시키고 그 특성을 관찰하였다. 결맞는 포논의 신호는 그림1)과 같이 반사 및 투과형 전기 광학적 샘플링(Reflective/Transmissive Electro-Optic Sampling： REOS/TEOS)방법과 여기-탐사광 방법으로 시간 영역에서 측정하였다. (중략)

• Macromolecular Research
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• 제11권5호
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• pp.393-397
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• 2003

By applying a configurational-bias Gibbs ensemble Monte Carlo algorithm, priority simulation results regarding the conformation of non-dilute polyelectrolytes in solvents are obtained. Solutions of freely-jointed chains are considered, and a new method termed strandwise configurational-bias sampling is developed so as to effectively overcome a difficulty on the transfer of polymer chains. The structure factors of polyelectrolytes in the bulk as well as in the confined space are estimated with variations of the polymer charge density.

• Safety and Health at Work
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• 제13권3호
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• pp.357-363
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• 2022

Background: Refractory ceramic fibers (RCFs) are a suspected carcinogen but have been widely used as insulations. Depending on the temperature, RCFs can transform into crystalline SiO₂, which is a carcinogen that can be present in the air during bulk RCF handling. This study analyzed the physicochemical and morphological characteristics of RCFs at high temperatures and determined the exposure levels during the semiconductor scrubber maintenance. Methods: Sampling was conducted at a company that manufactures semiconductor scrubbers using RCFs as insulation. Bulk RCF samples were collected both before and after exposure to a scrubber temperature of 700℃. Airborne RCFs were collected during scrubber maintenance, and their characteristics were analyzed using microscopes. Results: The components of bulk RCFs were SiO₂ and Al₂O₃, having an amorphous structure. Airborne RCFs were morphologically different from bulk RCFs in size, which could negatively affect maintenance workers' health. 58% of airborne RCFs correspond to the size of thoracic and respirable fibers. RCFs did not crystallize at high temperatures. The exposure caused by airborne RCFs during the scrubber frame assembly and insulation replacement was higher than the occupational exposure limit. Conclusion: Workers conducting insulation replacement are likely exposed to airborne RCFs above safe exposure limits. As RCFs are suspected carcinogens, this exposure should be minimized through prevention and precautionary procedures.

• 한국토양비료학회지
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• 제49권4호
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• pp.341-346
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• 2016

This study was conducted to analyze soil physico-chemical properties of agricultural land composed from the river-bed sediments. We investigated the changes of soil physico-chemical properties at 30 different sampling sites containing paddy, upland and plastic film house from 2012 to 2015. pH, exchangeable calcium and magnesium decreased gradually in paddy soils during the four years, whereas the available $P_2O_5$, exchangeable Ca, Mg and EC increased in upland and plastic film house soil. For the soil physical properties, bulk density and hardness of topsoil were $1.47g\;cm^{-3}$ and 21.5 mm and those of subsoil were $1.71g\;cm^{-3}$ and 25.7 mm in paddy soils. In upland soils, bulk density and hardness of topsoil were $1.48g\;cm^{-3}$ and 15.9 mm and those of subsoil were $1.55g\;cm^{-3}$ and 16.9 mm. In plastic film house soils, bulk density and hardness of topsoil were $1.42g\;cm^{-3}$ and 14.4 mm and those of subsoil were $1.40g\;cm^{-3}$ and 18.5 mm, respectively. The penetration hardness was higher than 3 MPa below soil depth 20 cm, and it is impossible to measure below soil depth 50 cm. As these results, in agricultural anthropogenic soils dredged from river basins, the pH, amount of organic matter and exchangeable cations decreased and soil physical properties also deteriorated with time. Therefore, it is needed to apply more organic matters and suitable amount of fertilizer and improve the soil physical properties by cultivating green manure crops, deep tillage, and reversal of deep soils.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.477-480
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• 2015

본 논문에서는 MPPT(Maximum Power Point Tracking) 제어 기능을 갖는 저전압 진동에너지 하베스팅 회로를 제안한다. 제안된 회로는 Bulk-driven technique을 적용하여 0.8V의 낮은 전압에서도 동작 가능하다. 압전소자의 출력단에 연결된 전파정류기의 개방회로 전압을 MPPT 제어회로를 통해 주기적으로 샘플링하고, 최대 가용전력 점의 전압을 부하에 전달한다. 제안된 회로는 0.35um CMOS 공정으로 설계되었으며, 패드를 포함한 칩 면적은 $1.33mm{\times}1.31mm$이다. 모의실험결과 설계된 회로의 최대 전력효율은 85.49%이다.