• 한국기계가공학회지
• /
• 제17권2호
• /
• pp.68-76
• /
• 2018

A vortex tube is a simple energy separating device that splits a compressed air stream into a cold and hot stream without any external energy supply or chemical reactions. The efforts of many researchers and designers have been focused on improvement of vortex tube efficiency by changing the parameters affecting vortex tube operation. The effective parameters are nozzle specifications and inflow pressure conditions. Effects of different nozzle cross-sectional area and number of nozzles are evaluated by computational fluid dynamics (CFD) analysis. In this study, CFD analysis of 3-D steady state and turbulent flow through a vortex tube was performed. We investigated the cold air mass flow rate, the cold air temperature, and the cold air heat transfer rate behavior of a vortex tube by utilizing seven straight nozzles and four inflow pressure conditions.

• 분석과학
• /
• 제27권4호
• /
• pp.213-222
• /
• 2014

국내 배경지역인 제주도 고산측정소에서 2012~2013년에 대기 미세먼지를 채취하여 분석한 결과로부터 연무와 비현상일의 조성특성을 조사하였다. 연무 시 $nss-SO_4{^{2-}}$, $NO_3{^-}$, $NH_4{^+}$ 농도는 비현상일에 비해 조대입자에서 2.1~3.7배, 미세입자에서 3.1~6.5배로 미세입자에서 더 높게 증가하였고, 특히 $NO_3{^-}$ 농도가 미세입자에서 6.5배 상승하였다. 원소성분들 중에는 S, Zn, Pb, K 등이 비현상일보다 조대입자에서 3.0~5.6배, 미세입자에서 3.2~7.7배 증가하나 Al, Fe, Ca 등은 대부분 조대입자에서 농도가 크게 증가하는 경향을 보였다. 역궤적 분석 결과 연무 시 $nss-SO_4{^{2-}}$, $NO_3{^-}$ 농도는 중국으로부터 유입되었을 때 더 높은 농도를 나타내었고, 특히 기류가 중국남부를 통과했을 때 $NO_3{^-}$ 농도가 더 크게 상승하는 경향을 보였다. 또 $NO_3{^-}/nss-SO_4{^{2-}}$ 농도비는 중국에서 기류가 이동했을 때 조대입자에서 상대적으로 높은 비율을 보이나 미세입자에서는 오히려 한반도를 통과했을 때 더 높은 성분비를 나타내었다.

• 대한원격탐사학회지
• /
• 제30권6호
• /
• pp.743-754
• /
• 2014

본 연구에서는 2005년부터 2008년 사이 한반도에서 고농도 $SO_2$가 관측된 날에 대하여 Ozone Monitoring Instrument (OMI) 이산화황자료 및 역궤적 계산을 통해서 중국으로부터 한반도로 장거리 수송되는 이산화황 flux의 계산 방법을 처음으로 소개하였다. 지표공기에서 측정된 이산화황 농도값과 OMI 센서에서 측정된 이산화황 층적분농도값을 이용하여 장거리 수송된 지표공기에서의 이산화황 flux와 지표부터 특정고도 사이 공기층 내에서의 평균 이산화황 flux를 각각 계산하였다. 위성관측을 이용하여 산출된 평균 flux값은 0.81 이고 최대 $2.11g{\cdot}m^{-2}{\cdot}h^{-1}$ 까지 산출되었고, 지점관측을 통한 지표공기로 유입되는 이산화황의 flux값은 평균 0.50 이고 최대 $1.18g{\cdot}m^{-2}{\cdot}h^{-1}$ 까지 산출 되었다. OMI센서와 지점관측 자료를 바탕으로 산출된 각각의 flux를 상호 비교하였으며 대부분의 경우 수용지역의 지표공기로 유입되는 이산화황 flux 값들이 지표부터 최대 1.5 km 사이의 장거리 수송되어 유입된 공기층 내의 평균 이산화황 flux 값들보다 높은 것으로 계산되었다. 발생원 지역에서 강한 저기압이 발견되는 경우를 포함하여 중국 발생원 지역으로부터 장거기 수송된 공기덩어리가 수용지역의 1.0에서 1.5 km 고도로 빠르게 유입되는 경우 지표부터 최대 1.5 km 사이 공기층 내의 평균 이산화황 flux 는 지표공기에서 산출된 flux 보다 높게 산출되는 경향을 보였다. 추가적으로 산출된 $SO_2$ flux값의 오차를 계산하고 오차값에 영향을 주는 인자들에 대해서 논의 하였다.

• 한국해양공학회지
• /
• 제2권2호
• /
• pp.130-137
• /
• 1988

This thesis introduced that character of a treatment technique for a mading synthetic resin Hifiow-Ring. The material system of packings make an experiment air$NH_{3}$/air$H_{2}SO_{4}$, $SO_{2}$-air/NaOH, $NH_{3}$-air/$/H_{2}SO_{4}$ under general conditions. Lattices packing compared with conventional packings was proved low pressure loss and high separation efficiency for high loading per trans unit. And an inflow materal tested for absorption and rectification, it made an experiment under a range regular temperature, low energy and small amount of money. That made possible in simple equation, volume material tranfer coefficient$\beta_{L}$ . a by absorption or $\beta_{V}$ .a calculated in all range loading. The peculiarity pressure loss $\Delta\;P/NUT_{ov}$ for Hiflow-ring contributed to a fall cost of energy, a grade number of a vacuum rectification and absorption calculation.

• 한국지구과학회지
• /
• 제28권1호
• /
• pp.123-135
• /
• 2007

동아시아에서 광역적인 대기오염 이동과 한반도 유입을 인공위성과 지상 관측을 통해 5개의 사례를 분석하였다. 이 사례들은 주로 중국 대륙의 도시와 산업지대에서 배출된 오염물질들이 황해를 지나 한반도에 상륙 및 통과하는 광역적인 대기오염 이동이다. NOAA인공위성 관측 자료의 분석은 가시영역과 적외선 영역의 3개 채널을 합성하여 영상을 만들고, 황해 위에서 대기오염의 분포와 이동을 구별해 낼 수 있었다. 또한 청원의 배경관측지점에서 대기오염의 지상 관측 자료는 인공위성 관측 자료와 비교하여 검증하는데 매우 가치가 있었다. 특히, 광역적 대기오염의 이동 사례에서는 $PM_{10}$과 $PM_{2.5}$ 농도의 차이가 적으면서, $PM_{2.5}$값이 높게 증가한다. 그러나 황사의 경우는 $PM_{10}$ 농도가 훨씬 높게 관측되어 $PM_{2.5}$와의 차이가 매우 큼이 특징적이다. 2006년 1월 27일의 사례에서는 중국 발원의 광역적 대기오염이 한반도의 중부 및 남서지역으로의 유입을 인공위성뿐 아니라 여러 지상관측소들에서 순차적으로 관측할 수 있었다. 북북서 기류가 제주도 한라산을 넘어서 풍하측 멀리까지 구름을 소산시키고 대기오염을 감소시키며, 카르만 소용돌이를 만들고 있었다.

• 한국대기환경학회지
• /
• 제29권5호
• /
• pp.553-573
• /
• 2013

This paper aims to give a summary and review of the research trend about subjects of Asian Dust (AD) storm in the last three decades. The AD research was focused on classification of synoptic scale data and finding inflow pathway in early stage. Recently, new approaches have been made to explain chemical composition, transportation, transboundary movement reaction of AD, using satellite data, 3D modeling, the aerosol time of flight mass spectroscopy, etc. During AD events, a large amount of dust particles flow into Korea and Japan from AD source areas, and they are highly likely to be mixed with toxic substances when air mass contained AD particles pass over seriously polluted areas. We concluded that, considering that AD events were classified into two cases according to the source area and pathway, the concentrations of crustal components did not increase at the initial stage of AD events, Whereas ammonium-sulfate, trace metal element, OC, EC relatively increased in the early stage. This explains AD events have the possibility of being accompanied with polluted air mass or particles. Also, we further need to compare and summarize the results of AD studies which already have been conducted, and prepare strategies for particle management, particularly for Black Carbon (BC) and Brown Carbon (BrC) which are considered to induce climate change effects.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1998년도 추계학술대회 논문집
• /
• pp.235-241
• /
• 1998

Flow characteristics of a compressible gas flow through a rotating disc-type rotary valve are investigated experimentally under various conditions. It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stroke cycle engines decrease with increase in engine speed. Rotary valve is one means by which air maybe made to flow intermittently through a pipe. In this paper a exhaust system simulator of engine was used to experimentally analyzer the decrease inflow rate at high rotation speeds and to determine what variables, other than rotational speed, give rise to the observed behaviour. These variables have been included in an empirical equation which is representative of the measured flow characteristics.

• 한국대기환경학회지
• /
• 제34권5호
• /
• pp.677-686
• /
• 2018

An intensive measurement was conducted to study the mass and number concentrations of atmospheric aerosols in Anheung ($36.679^{\circ}N$, $126.186^{\circ}E$), the west coastal measurement site of Korea during December 2017~April 2018. To evaluate relationships between the aerosols and meteorological parameters, comparisons of Optical Particle Counter (OPC) measured data and Auto Weather System (AWS) data were performed. Measured PM mass concentrations are $PM_{10}=42.814{\pm}30.103{\mu}g/m^3$, $PM_{2.5}=29.674{\pm}25.063{\mu}g/m^3$, $PM_1=28.958{\pm}24.658{\mu}g/m^3$, respectively. The PM ratios showed that the $PM_{10}$ concentrations contained about 67.8% of $PM_{2.5}$, while most part of $PM_{2.5}$ was $PM_1$ (about 97.1%). Timely collocation with AWS data were performed, exploring relations with the PM concentrations. PM concentrations can be explained by wind direction and relative humidity conditions. The significant reductions of fine particles in mass and number concentrations may attribute to actions on particle growth and wet removal. In these results, we suppose that the aerosol concentrations and size distributions are affected by inflow direction and air mass sources from the origin.

• 한국대기환경학회지
• /
• 제32권5호
• /
• pp.469-484
• /
• 2016

HR-ToF-AMS was applied for a seasonal and size-distributional measurements for inorganic ($SO{_4}^{2-}$, $NO_3{^-}$, $NH_4{^+}$, $Cl^-$) and organic components in Baegryung Island Super Site. The average concentration of $PM_{1.0}$ remarks $12.9{\mu}g/m^3$ while $14.5{\mu}g/m^3$ in Spring time, $14.2{\mu}g/m^3$ in Winter, $13.1{\mu}g/m^3$ in Summer and $9.86{\mu}g/m^3$ in Autumn. The mass of measured $PM_{1.0}$ shows 54.6% of $PM_{2.5}$ which is similar to those of Beijing and Lanzhou, China. The highest portion of Chemical composition is $SO{_4}^{2-}$ marking 41.0%, 31.8% by organics, 13.5% by $NH_4{^+}$, 12.8% by $NO_3{^-}$ and 1% by $Cl^-$. In every seasons, except winter, $SO{_4}^{2-}$ remarks the highest level, organic components take place the highest in winter time. The size-distribution of $PM_{1.0}$ components scattered at accumulation mode of 200 nm~800 nm which means the influence of primary emission is low. In case of air stream from the industrialized area of Sandung, Shanghai, China, the concentrations of such components were distributed a bit higher.

• 한국대기환경학회지
• /
• 제29권1호
• /
• pp.86-96
• /
• 2013

The realtime monitoring of radon ($^{222}Rn$) concentrations has been carried out from Gosan site, Jeju Island for three years of 2006~2008, in order to evaluate the background level and timely variational characteristics of atmospheric radon. The mean concentration of radon measured during the studying period was $2965mBq/m^3$ with its annual mean values in the range of $2768{\sim}3124mBq/m^3$. The relative ordering of the seasonal mean concentrations was seemed to vary such as winter ($3578mBq/m^3$) > fall ($3351mBq/m^3$) > spring ($2832mBq/m^3$) > summer ($2073mBq/m^3$). The monthly mean concentrations were in the order of Jan>Feb>Oct>Nov>Dec>Mar> Sep>Apr>May>Jun>Aug>Jul, so that the highest January value ($3713mBq/m^3$) exceeded almost twice as the July minimum ($1946mBq/m^3$). The hourly concentrations in a day showed the highest level ($3356mBq/m^3$) at around 7 a.m., increasing during nighttime, while reaching the lowest ($2574mBq/m^3$) at around 3 p.m. From the backward trajectory analysis for a continental fetch of radon, the high concentrations (10%) of radon matched with the air mass moving from the Asia continent to Jeju area. In contrast, the low concentrations (10%) of radon were generally correlated with the air mass of the North Pacific Ocean. In comparison by sectional inflow pathways of air mass, the radon concentrations were relatively high from the north China and the Korean peninsula.