• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.185-192
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• 1996

In order to simulate the coastal dispersion effectively, hybrid concept of operator split Eulerian-lagrangian concentration model and random-walk particle tracking model are developed. Especially the random-walk model is adequate for region with steep slope of concentration. According to model tests, it agrees perfectly with analytical solution on around the source point for therefore. ▽C $\geq$ 0.005, meanwhile it shows poor results for ▽C$\leq$0.002. trial modeling for real situation therefore, random-walk model is applied for near field henceforth Eulerian-Lagrangian concentration model is adoped for whole domain so that overall performance and accuracy can be achieved by using developed hybrid model.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.602-609
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• 1997

The seed formation and growth of $\alpha$-ferric oxyhydroxide with aerial oxidative precipitation from aqueous solution of ferrous sulfate with KOH, NaOH, $Na_2CO_3$ and $K_2CO_3$ as precipitants have been studied by free pH drift experiment. It has been shown that all precipitants give same particle formation and growth path, and average particle length from KOH and NaOH as precipitants was about 1.5 times shorter than that of $K_2CO_3$ and $Na_2CO_3$. When initial mole ratio, $R_o=[Fe^{2+}]_o/[OH^-]_o$ of KOH was decreased the particle was grown oxyhydroxide seed growth from aqueous solution of ferrous sulfate with KOH has been studied. The influence of the air flow rate, reaction temperature and initial mole ratio, $R_o=[Fe^{2+}]_o/[OH^-]_o$, on the kinetics of seed growth are investigated by static pH experiment. The oxidation rate of seed growth increased with increase in the air low rate, reaction temperature and initial mole patio. The activation energy of seed growth is 16.16 KJ/mol and the rate equation of seed growth can be written as follows: $-\frac{d[Fe^{2+}]}{dt}=1.46{\times}10^4[P_{o2}]^{0.66}[OH^-]^{2.19}exp(-\frac{16.16}{dt})$.

• Clean Technology
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• v.28 no.2
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• pp.123-130
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• 2022

Nanoparticles are used in various fields such as chemistry, medicine, the environment, and information and communication. With the increasing use of engineered nanomaterials, exposure to nanoparticles is expected to increase in the workplace and the environmental media. However, while nanotechnology industries are expanding, research on the exposure assessment of nanomaterials to humans and the environment is only at a beginning stage. Especially, if nanoparticles with a size of 100 nm or less that are contained in nano-products are released unintentionally, they may pose potential risks to the human body through breathing or skin exposure. Therefore, in this work, the possibility of potential exposure of nanoparticles moving from the laboratory to the office was confirmed, and nanoparticle safety guidelines are proposed. A nano-collector was used to detect nanoparticles in the atmosphere, and through use of a scanning mobility particle sizer it was found that nanoparticle concentrations in the laboratory and the office tended to be similar. On the assumption that nanoparticles attached to a lab-coat move out of the laboratory, a lab-coat to which nanocarbon black was attached was shaken and the concentration of the remaining particles on the lab-coat determined. The results confirmed that sufficient amounts of nanoparticles attached to the lab-coat could move from the laboratory to the office along the path of a researcher; thus, safety guidelines for the handling of lab-coat nanoparticles are required.

• Progress in Medical Physics
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• v.6 no.1
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• pp.39-47
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• 1995

In order to accurate treat damage induced by ionizing radiation in biological system on the cellular or subcellular level with physical parameters characterising the radiation, specific primary ionization (SPI) is introduced as the parameter which does not suffer from limitation of linear energy transfer (LET). In this present study, we calculate specitic primayt ionization with total ionization cross section (TICS) of electrons, protons and alppa particles incident on water. The used energy ranges cover those that have been freqently used in radiobioligical experiments. For electrons above 1 keV, we have relativistic corrections and also compare the results with other data. For electrons energies below 100keV, our results are in excellent agreement with theoretical calculations published recently by (perris and zarris 1987). These results may be easily applied by the interested radiobiogists.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.9
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• pp.1117-1123
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• 2004

The characteristics of soot near the soot inception point for an ethene-air flame was carried out in a WSR (well-stirred reactor). The new sampling tool like the temperature controlled filter system was introduced to minimize the condensation during sampling. The new analysis tools applied include the real time size distribution analysis with the Nano-DMA, particle size by transmission electron microscopy, C/H analysis, g filter analysis, and thermogravimetric analysis using both non-oxidative and oxidative pyrolysis. The WSR can generate young soot particles that can be collected and examined to gain insight into inception. For the current conditions, soot does not form for ${\Phi}$=1.9, inception occurs at or before ${\Phi}$=2.0, and inception combined with soot surface growth and/or coagulation occurs for ${\Phi}$=2.1. The filter samples for ${\Phi}$=1.9 are composed of volatile compounds that evolve at relatively low temperatures when heated in the presence or absence of O$_2$. The samples collected from the WSR at ${\Phi}$=2.0 and ${\Phi}$=2.1 are precursor-like in morphology and size. They have higher C/H ratios and lower organic percentages than precursor particles, but they are clearly not fully carbonized soot. The WSR PAH distribution is similar to that in young soot from inverse flames.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.65-71
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• 2018

There is no significant difference in the initial viscosity of a propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material with added yellow iron oxide is faster than that with the addition of red iron oxide. Specifically, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure with yellow iron oxide than with red iron oxide. The initial viscosity was lowest at 71% of the large particle to small particle ratio.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1298-1303
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• 2004

The characteristics of soot near the soot inception point for an ethene-air flame was carried out in a WSR (well-stirred reactor). The new sampling tool like the temperature controlled filter system was introduced to minimize the condensation during sampling. The new analysis tools applied include the real time size distribution analysis with the Nano-DMA, particle size by transmission electron microscopy, C/H analysis, g filter analysis, and thermogravimetric analysis using both non-oxidative and oxidative pyrolysis. The WSR can generate young soot particles that can be collected and examined to gain insight into inception. For the current conditions, soot does not form for ${\Phi}=1.9$, inception occurs at or before ${\Phi}=2.0$, and inception combined with soot surface growth and/or coagulation occurs for ${\Phi=2.1}$. The filter samples for ${\Phi}$=1.9 are composed of volatile compounds that evolve at relatively low temperatures when heated in the presence or absence of $O_2$. The samples collected from the WSR at ${\Phi}=2.0$ and ${\Phi}=2.1$ are precursor-like in morphology and size. They have higher C/H ratios and lower organic percentages than precursor particles, but they are clearly not fully carbonized soot. The WSR PAH distribution is similar to that in young soot from inverse flames.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.498-503
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• 2017

There is no unusual difference in the initial viscosity of the propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material added with yellow iron oxide is faster than that of the addition of red iron oxide. Especially, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure. The initial viscosity was lowest at 71% of large particle/small particle ratio

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.496-496
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• 2022

차량 운행이 많은 고속도로, 주차장, 교량 등의 불투수 면적에서 발생하는 비점오염 물질은 차량에서 발생하는 배기가스와 연료, 부품 등이 비강우시 노면에 축적된 후 강우시 유출되는 특징을 가진다. 고속도로 휴게소의 경우 넓은 부지에 주차장이 위치하고, 대부분 불투수면으로 설계되었으며 차량이용대수에 따라 수질오염물질, 중금속 등이 축적되어 강우시 초기에 다량의 오염물질이 유출되는 특징을 가진다. 특히, 휴게소 노면 배출지점에서 강우시 약간의 탁수 유입과 함께 유기물, 영양염류의 농도가 다소 높았으며, 중금속은 주로 Pb, Cu, Zn의 농도가 높게 나타나는 것으로 연구 되었다. 본 연구는 고속도로 휴게소에서 발생하는 오염물질의 특성을 파악하기 위해 실시하였다. 휴게소 및 고속도로 인근에서 평시 발생하는 오염원의 차량 기인 여부를 판단하기 위해 비강우시 고속도로 노면 및 휴게소 오염원 배출 지점에서 토사 및 입자 샘플링을 실시하였으며, 이를 통해 입자에 흡착된 중금속 오염도 및 차량기인 여부를 판단하였다. 본 연구를 통해 고속도로 휴게소에서의 초기강우시 오염물질 처리방안 계획 수립시 기초자료로 활용할 수 있을 것으로 기대한다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2000.09a
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• pp.126-132
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• 2000

하수처리장의 수중확산관에서 방류되는 부력제트는 초기혼합, 중력확장, 이송-확산 등의 과정이 시간적, 공간적으로 규모가 상이한 범위에서 일어나며, 하수방류 해역의 주변수 흐름은 지형특성과 조석의 영향을 받아 3차원적 비정상류 특성을 나타낸다. 이러한 부력제트의 거동을 모의하기 위해서는 일반적으로 근역과 원역을 분할하여 예측하는 방법을 사용하는데, 초기혼합 과정과 중력환장 과정을 예측하기 위해서는 정상상태는 가정한 특성길이 모형이나 제트적분 모형을 사용하고, 원역으로의 이송-확산 과정을 모의하기 위해서는 농도 모형이나 임자추적 모형등을 사용한다. (중략)