• 한국환경과학회지
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• 제24권5호
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• pp.615-622
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• 2015

East Asia is characterized by anthropogenic emissions resulting from the large population and fast economic growth of this region. Since the prevailing wind is westerly and northwesterly, emissions from Ul-jin can be expected to contribute to acidic deposition increase in downwind direction. Aerosols collected at the near coast site, Uljin geun, gyungbook and were analyzed for $NH_4{^+}$, $Mg^{2+}$, $Na^+$, $Ca^{2+}$, $Cl^-$, $SO_4{^{2-}}$, and $NO_3{^-}$ from Aug. 2012 to Feb. 2013. The seasonal averaged aerosol concentration showed the highest potassium and calcium ion in winter and the highest ammonium ion due to a meadow and high solar intensity in summer. Sodium and chloride ion showed the same ratio all seasons and sulfate and nitrate species showed the maximum value in winter Chemical components of aerosols collected at the near coast site, Uljin geun, gyungbook were lower by 16 to 73% than those collected at other similar environment site such as kanghwa, yangyang. Comparing air quality data at the near coast site, Uljin geun, gyungbook, There was found that Uljin coast site is less influenced by the sea salts(potassium, magnesium, calcium) and nss-$SO_4{^{2-}}$ percentage is 3~13% higher than similar condition site.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1572-1576
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• 2006

A dimeric precursor, $[Cu(dmae)(OCOCH_3)(H_2O)]_2$ for the CVD of copper metal films, (dmaeH = N,N-dimethylaminoethanol) was synthesized by the reaction of copper(II) acetate monohydrate ($Cu(OCOCH_3)_2{\cdot}H_2O$) and dmaeH in toluene. The product was characterized by m.p. determination, elemental analysis and X-ray crystallography. Molecular structure of $[Cu(dmae)(OCOCH_3)(H_2O)]_2$ shows that a dimeric unit $[Cu(dmae)(OCOCH_3)(H_2O)]_2$ is linked to another through hydrogen bond and it undergoes facile decomposition at 300 C to deposit granular copper metal film under nitrogen atmosphere. The decomposition temperature, thermal behaviour, kinetic parameters, evolved gas pattern of the complex, morphology, and the composition of the film were also investigated.

• 대한기계학회논문집A
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• 제32권8호
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• pp.617-623
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• 2008

The membrane filter adhered with nanostructured porous layer was made by heat treatment after deposition of nanoparticle-agglomerates sintered in aerosol phase onto a conventional micron-fibrous metal filter as a substrate filter. The Sintered-Nanoparticle-Agglomerates-coated NanoStructured porous layer Membrane Filter (SNA-NSMF), whose the filtration performance was improved compared with the conventional metal membrane filters, was developed by adhesion of nanoparticle-agglomerates of dendrite structure sintered onto the micron-fibrous metal filter. The size of nanoparticle-agglomerates of dendrite structure decreased with increasing the sintering temperature because nanoparticle-agglomerates shrank. When shrinking nanoparticle-agglomerates were deposited and treated with heat onto the conventional micron-fibrous metal filter, pore size of nanostructured porous layer decreased. Therefore, pressure drops of SNA-NSMFs increased from 0.3 to 0.516 kPa and filtration efficiencies remarkably increased from 95.612 to 99.9993%.

• 한국대기환경학회지
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• 제25권6호
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• pp.539-549
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• 2009

The purpose of this study is to estimate hourly Asian dust emission flux in springtime by using the optimized Weather Research Forecasting model (WRF) in order to accurately predict the horizontal flux of Asian dusts. Asian dust emission flux using 5 empirical formulas such as US EPA, Park and Inn, Wang, The Goddard Chemistry Aerosol Radiation and Transport (GOCART) and Dust Entrainment and Deposition (DEAD) were calculated and compared by using classified land-use types and size distribution at various locations in China and Mongolia together with the hourly meteorological elements of the WRF model. As a result, the empirical formula in US EPA among them, which was considered the various conditions such as vegetation, soil type and terrain, was better than the other 4 empirical formulas. However, these formulas were adjusted hourly and vertically in time and space because there was different order and time resolution of dust emissions from original empirical formulas.

• 대한의용생체공학회:의공학회지
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• 제33권4호
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• pp.177-183
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• 2012

The inspiratory flow rate of a human is changed with the amount of the workload. The flow characteristic is affected by the inspiratory flow rate. In the flow field of airway, the both of turbulence intensity and secondary flow affect the deposition pattern of particles which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The relatively inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. The low Reynolds number k-${\omega}$ turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the turbulence kinetic energy and secondary flow intensity increase in airway. On the other hand, the area of recirculation zone is smaller.

• Korean Chemical Engineering Research
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• 제46권2호
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• pp.397-401
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• 2008

레이저 애블레이션에 의해서 가지상 구조체 형상인 나노입자 응집체를 합성하였다. 기존 마이크론 금속섬유 필터의 표면상에 나노입자 응집체를 고착하여 여과성능을 향상시켰다. 에어로졸 상에서 소결 처리된 나노입자 응집체를 증착한 후 열처리를 하여 나노구조체가 표면상에 형성된 소결 처리된 나노입자 응집체 고착 필터를 제작하였다. 소결 온도가 증가할수록 마이크론 금속섬유 필터 표면상에 고착된 나노입자 응집체의 표면적 증가로 인하여 차압은 조금 증가하지만 여과효율은 현저하게 증가하였다.

• 한국재료학회지
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• 제31권10호
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• pp.546-551
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• 2021

To improve ferroelectric properties of PZT, many studies have attempted to fabricate dense PZT films. The AD process has an advantage for forming dense ceramic films at room temperature without any additional heat treatment in low vacuum. Thick films coated by AD have a higher dielectric breakdown strength due to their higher density than those coated using conventional methods. To improve the breakdown strength, glass (SiO₂-Al₂O₃-Y₂O₃, SAY) is mixed with PZT powder at various volume ratios (PZT-xSAY, x = 0, 5, 10 vol%) and coating films are produced on silicon wafers by AD method. Depending on the ratio of PZT to glass, dielectric breakdown strength and energy storage efficiency characteristics change. Mechanical impact in the AD process makes the SAY glass more viscous and fills the film densely. Compared to pure PZT film, PZT-SAY film shows an 87.5 % increase in breakdown strength and a 35.3 % increase in energy storage efficiency.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.400-401
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• 2003

Atmospheric fine aerosol particles play an important role in controlling a number of atmospheric processes, such as the deposition of different compounds, the optical properties etc. (Molnar et al., 1999). In this report, water-soluble species of PM$_{2.5}$ obtained from simultaneous measurements at four Asia sites (Beijng (39.56$^{\circ}$N, 116.17$^{\circ}$E), China; Gwangju (35.10$^{\circ}$N, 126.53$^{\circ}$E), South Korea; Kyoto (35.01$^{\circ}$N, 135.44$^{\circ}$E), Japan; and Ulan-Bator (47.55$^{\circ}$N, 106.52$^{\circ}$E), Mongolia) during the periods of 14-22 August, 30 October-06 November 2000, 14-21 January 2001, 23 July-02 August and 05-16 November 2002, within the framework of an APN (The Asia-Pacific Network for Global Change Research) project are reported. Ion components in 23 July-02 August 2002 were not obtained because of the technical problem of equipments.s.

• 자원환경지질
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• 제38권4호
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• pp.463-479
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• 2005

전북의 전주, 군산, 남원지역에서 주기적으로 채수된 강수(bulk deposition)를 지화학적으로 고찰하고 Sr과 Pb 동위원소의 환경추적인자로서의 적용 여부를 알아보고자 하였다. 강수는 pH $4\~7$의 약산성내지 산성을 띄며, 건기에는 높고, 우기에는 자연산성도 수준인 5.0수준을 유지한다. 강수에 의한 희석작용으로, 우기이후의 강수는 TDS 및 EC도 낮아지나 다시 건기에 들어서면서 상승한다. 겨울철에는 난방연료의 연소에 의해 $SO_4$과 $NO_3$이 높은 함량을 보이며, 여름철은 $CO_2$가스의 영향으로 탄산농도가 약간 높은 경향을 보인다 양이온은 겨울철에 Na의 함량이 높고, 봄부터 여름철에는 Ca의 함량이 높게 나타난다. 지리산에 인접한 남원이 전반적으로 낮은 EC 및 TDS값을 가지고 인구밀집과 도시화가 심한 전주지역은 대체로 높다. 남원지방은 다량의 수목의 호흡작용에 의한 대기중 이사화탄소의 함량이 높아 여름철 탄산 농도가 타 지역에 비해 높다. 군산지역은 해염의 영향으로 대기중 Cl의 함량이 높다. Al, Cu, Zn은 TDS와 상관계수 0.5이상의 양호한 상관관계를 보여 이들 원소가 미량원소 중 강수의 화학적 성상에 영향을 미치는 원소들 이라고 볼 수 있다. $^{87}Sr/^{86}Sr$ 값은 0.7109-0.7128으로 세 지역 모두 유사하며, 해수보다 다소 높은 값을 보이고 있어 주변의 토양입자, 꽃가루, 기타 인위기원의 에어로졸 등의 영향이 있음을 암시하나 지역 전반에 걸친 자세한 동위원소적 고찰이 있어야만 보다 정확한 해석이 가능할 것으로 생각된다. 강수의 Pb 동위원소 조성도 세 지역 모두 유사하며, 서울 에어로졸의 Pb 동위원소 조성 범위내에 포함되고 북경의 에어로졸 범위에서는 약간 벗어나 있다. 이는 한반도내의 대기 중에 함유되어 있는 Pb은 모두 유사한 기원으로 휘발유의 연소에서 발생하는 것으로 생각되며, 중국으로부터 기원한 Pb의 존재 가능성은 내포하고 있으나 그 기여율은 적을 것으로 보인다.

• 대한기계학회논문집B
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• 제27권2호
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• pp.197-205
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• 2003

A cascade impactor is a multistage impaction device used to separate airborne particles into aerodynamic size classes. A micro-orifice impactor uses micro-orifice nozzles to extend the cut sizes of the lower stages to as small as 0.05 ${\mu}{\textrm}{m}$ in diameter without resorting to low pressures or creating excessive pressure drops across the impactor stages. In this work, the phenomenon of particle clogging in micro-orifice nozzles was experimentally investigated for a commercial micro-orifice uniform deposit impactor (MOUDI). It was observed, using an optical microscope, that the micro-orifice nozzles of the final stages were partially clogged due to particle deposition during the aerosol sampling. Therefore the pressure drops across the nozzles were higher than the nominal values given by the manufacturer. To examine the effect of particle clogging in micro-orifice nozzles, the particle collection efficiency of the MOUDI was evaluated using an electrical method for fine particles with diameters in the range of 0.1-0.6 ${\mu}{\textrm}{m}$. The monodisperse liquid dioctyl sebacate (DOS) particles were used as test aerosols. A faraday cage was employed to measure the low-level current of the charged particles upstream and downstream of each stage. It was found that the collection efficiency curves shifted to correspond to smaller orifice sizes, and the 50-% cutoff sizes were much smaller than those given by the manufacturer for the three stages with nozzles less than 400 ${\mu}{\textrm}{m}$ in diameter.