• 한국해양환경ㆍ에너지학회지
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• 제6권4호
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• pp.13-23
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• 2003

Organic carbon and nitrogen contents in suspended particulate matter (SPM) and surface sediments in seawater were measured in the Northern East China Sea in summer. The distribution of particulate organic carbon(POC) and particulate organic nitrogen(PON) were in the ranges of 54~481㎍/ℓ and 6~85㎍/ℓ, respectively, with relatively high level of concentrations in the western and southern sides of the study area. Also, there has been a significantly positive correlation between POC and PON, gradually increasing toward the deeper range of depth. Average C:N ratios of POC and PON of SPM were 6 in study area. The ratios of POC to PON of SPM increased as the range of depth increased, indicating nitrogen decomposes more rapidly than carbon and is considered to be influenced by the input of detritus from surface sediments. The distribution of total organic matter(TOM), total organic carbon(TOC) and total organic nitrogen(TON) in surface sediments were in the ranges of 3.1~9.6%, 0.282~0.635% and 0.022~0.069%, respectively, with relatively low range in the western and northern sides of the study area. The ratio of TOC to TON of surface sediments were in the range of 9.8~17.4(average of 13), strongly indicating the active role of the input from the terrestrial organic pollutants.

• 한국정밀공학회지
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• 제24권5호
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• pp.82-88
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• 2007

This work is to fabricate a precise optical fiber array using polymer composite for optical interconnection. Optical fiber array has to satisfy low optical loss requirement less than 0.4 dB according to temperature change. For this purpose, design criteria for an optical fiber array was derived. The coefficient of thermal expansion of silica particulate epoxy composites was affected by volume fraction of silica particles. And also, elastic modulus of silica particulate epoxy composites was affected by volume fraction of silica particles. To obtain the coefficients of thermal expansion below $10{\times}10E-6/^{\circ}C$ and elastic modulus more than 20 GPa , we chose the volume fraction more than 76%. Using silica particulate epoxy composites with the volume fraction 76%, 8-channel optical fiber array with dimensional tolerances below $1\;{\mu}m$ was manufactured by transfer molding technique using dies with the uniquely-designed core pin and precisely-machined zirconia ceramic V block. These optical fiber arrays showed optical loss variations within 0.4 dB under thermal cycling test and high temperature test.

• 한국자동차공학회논문집
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• 제17권1호
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• pp.24-34
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• 2009

DPF(Diesel Particulate Filter)s have been used to reduce the most of PM(particulate matters) from the exhaust emissions of diesel engine vehicles. Metal foam is one of promising materials for the DPFs due to its cost effectiveness, good thermal conductivity and high mechanical strength. It can be fabricated with various pore sizes and struct thickness and coated with catalytic wash-coats with low cost. In order to design metal foam filter and analyze the flow phenomena, pressure drop and filtration experiment are carried out. Partial DPF which has PM reduction efficiency of more than 50 % is designed in this paper. Also, CFD analysis are performed for different configurations of clean filters in terms of pressure drop, uniformity index, and velocity magnitude at face of filter. Filter thickness and the gap between front and rear filters are optimized and recommended for manufacturing purpose.

• 설비공학논문집
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• 제17권3호
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• pp.262-267
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• 2005

The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate and to model the air-side particulate fouling characteristics of the heat exchangers using accelerated particle loading system. The main variables of the modeling equation are face velocity and dust concentration. The modeling equation shows good agreements with the experimental results at the face velocity of 0.5, 1.0, 1.5 m/s and the dust concentration of 1.28 and $3.84\;g/m^3$. It will be very useful to predict fouling characteristics such as variations of pressure drop and heat transfer capacity in finned-tube heat exchangers of air conditioners.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.75-80
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• 2006

Since air pollution has become a globally critical issue and exhaust emissions from automobiles cause a major source of air pollution, many countries including advanced countries have stipulated stringent emission regulations. Particularly in diesel vehicles, NOx and particulate matters exhaust in significant amounts even though diesel vehicles provide merits in aspects of higher thermal efficiency and lower $CO_2$. To reduce Particulate matters and NOx, after-treatment technology such as filter trap, oxidation catalysts and EGR has been applied. This test was conducted on the effect of continuous regeneration diesel particulate filter and cooled-EGR, and 15ppm low sulfur diesel was used as a test fuel. Exhaust emissions, PM, NOx, CO, HC and Soots were measured and compared under D-13 and D-3 modes.

• 한국환경보건학회지
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• 제33권1호
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• pp.36-42
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• 2007

Diesel PM can be controlled using Diesel Particulate Filter, which can effectively reduce the level of soot emissions to ambient background levels. In the Heavy Duty Diesel area, the Continuously Regeneration trap has been widely applied in the retrofit market. As the Special act for the improvement of air quality in the capital area, the retrofit program for DPF to used diesel vehicle has progressed favorably and there are currently over 1,000 of these DPF in use in retrofit applications in korea. These DPF comprise a specially formulated Diesel Oxidation Catalyst upstream of a DPF. The $NO_2$ generated by the DOC is used to combust the carbon collected in the DPF at low temperature. To certificate DPF device that is suitable to domestic circumstances, it is necessary to evaluate exactly the DPF devices according to the regulation of DPF certificate test procedure for retrofit(ministry of environment(MOE) announcement NO. 2005-16). To do so the understand of that regulation like the standard of PM reduction rate is needed. In this study the test procedure including test cycle and BPT test condition was examined and also the test result for specific DPF was analyzed. In every test like field test, PM reduction efficiency test and seoul-10 mode test, no defect could be showed.

• 한국의류학회지
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• 제25권8호
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• pp.1465-1474
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• 2001

The dispersion stability of particles and the adsorption of surfactant were examined as a fundamental environment to adhesion of particulate soil to fabric. The adsorption of surfactant on the PEF fabrics decreased with the addition of electrolytes and decreased with increasing the ionic strengths showed similar tendency to PET fabric. And the dispersion force of $\alpha$-Fe$_2$O$_3$particles decreased with the addition of electrolyte. The adhesion of particulate soil to fabric, increased with decreasing the adsorption of surfactant the correlation between the two was high at low ionic strength. The correlation between the adsorption of surfactants on $\alpha$-Fe$_2$O$_3$ particles and the adhesion of particles to fabric was smaller as shown in the correlation between the adsorption of surfactants on fiber substrate and the adhesion of particles on fabric. However, the correlation between the adhesion of particles to fabric and the stability of particle dispersion was relatively more significant.

• 유변학
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• 제9권2호
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• pp.73-80
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• 1997

분말 입자 형태가 다른 2가지 스테인레스 강(SUS 316L)분말과 조성이 다른 2가지의 결합제를 이용하여 분말충전율의 변화를 가지도록 제조된 5가지 분말사출재에 대한 Bagley 보정 실험을 실시하여 Bagley 보정값에 대한 온도, 분말충전율, 분말 입자 형태 그리고 결 합제의 영향을 조사하였다. Bagley 보정값을 구하기 위한 자료 처리를 하는 과정에서 길이 가 긴 모세관(L/D=60) 의 압력손실이 Thixotropy에 의해서 감소한 현상을 발견하였다. 이는 모세관 점성측정기를 이용한 분말사출제의 점도 측정시 길이가 긴모세관의 사용이 바람직하 지 못하다는 것을 나타낸다. 분말사출재의 Bagley 보정값에 대한 온도와 결합제의 영향은 매우 미약하게 나타났는데 특히 결합제의 영향은 거의 나타나지 않는 것을 발견하였다. 분 말충전율과 분말 입자 형태의 Bagley 보정값에 대한 영향은 매우 크게 나타났으며 분말충 전율이 증가할수록 Bagley 보정값이 증가하고 분말 입자의 형태가 불규칙한 분말을 사용한 분말사출재의 보정값이 구형의 분말에 비해 높은 보정값을 나타냈다. 실험결과에 대한 고찰 결과, 분말사출재의 모세관 입출구에서 압력손실의 주 원인은 분말 이자간 마찰과 충돌이라 고 판단되었다.

• 한국전산유체공학회지
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• 제6권4호
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• pp.8-14
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• 2001

The phenomena of two-phase suspension flows appear widely in nature and industrial processes. Hence, it is of great importance to understand the mechanism of the gas-solid two-phase flows. In the present study, the numerical simulation has been approached by utilizing the Eulerian-Lagrangian methodology for describing the characteristics of the fluid and particulate phases in a vertical pipe and a 90°square-sectioned bend. The continuous phase(gas phase) is described by the Eulerian formulation and a κ-ε turbulence model is employed to find mean and turbulent properties of the gas phase. The particle properties(velocity and trajectory) are then described by a Lagrangian approach and computed using the mean velocity and turbulent fluctuating velocity of the gas phase. The predictions are compared with measurements by laser-Doppler velocimeter for the validation. As a result, the calculated results show good agreements.

• 한국습지학회지
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• 제19권4호
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• pp.451-458
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• 2017

본 연구에서는 비용효율적인 인공습지의 설계를 위하여 초기 침강지 내 다양한 도류벽형태에 따른 인공습지의 사수역 및 입자상 물질의 제거효율을 전산유체역학(Computational Fluid Dynamics, CFD)을 통해 연구하였다. 그 결과, 초기 침강지에서 도류벽의 형태는 유입 유속에 영향을 미치며, 침전률에도 큰 영향을 미치는 것으로 분석되었다. $2{\mu}m$ 와 $5{\mu}m$와 같은 미세한 입자에서는 수평으로 설치한 도류벽에서 침전률이 높았으며, $10{\mu}m$와 $20{\mu}m$ 크기의 큰 입자는 수직형 도류벽에서도 높은 침전률을 나타내었다. 또한, 수직형 도류벽의 경우 좁은 면적에 침전이 집중적으로 이루어지기에 다른 형태에 비해 유지관리가 효율적일 것으로 판단되었다. 이에 인공습지의 설계 목적에 따라 가장 적절한 도류벽의 형태를 선정하여 설계해야 할 것으로 보여진다.