Two step rapid filter system as a pre-treatment for the injected water into aquifer storage and recovery (ASR) in Korea was developed to reduce physical blockage and secure the volume of the injected water. First, single rapid sand filters with three different media sizes (0.4~0.7, 0.7~1.0 and 1.0~1.4 mm) were tested. Only two sizes (0.4~0.7 and 0.7~1.0 mm) satisfied target turbidity, below 1.0 NTU. However, they showed the fast head loss. To prevent the fast head loss and secure the volume of the injected water, a rapid anthracite filter with roughing media size (2.0~3.4 mm) were installed before a single rapid sand filter. As results, both the target turbidity and reduction of head loss were achieved. It was determined that the media size for a rapid sand filter in two step rapid filter system (i.e. a rapid anthracite filter before a rapid sand filter) was 0.7~1.0 mm. In addition, the effects of coagulant doses on the removal of natural organic matter (NOM), which might cause a biological clogging, were preliminarily evaluated, and the values of UV254, dissolved organic carbon (DOC) and SUVA were interpreted.

The Cu nanofluid in ethylene glycol was prepared by electrical explosion of wire, a novel one-step method. The X-ray diffraction, field emission scanning electron microscope and transmission electron microscope were used to study the properties of Cu nanoparticles. The results showed that the nanoparticles were consisted of pure face-centered cubic structure and near spherical shape with average grain size of 65 nm. Ultraviolet-visible spectroscopy (UV-Vis) confirmed Cu nanoparticles with a single absorbance peak of Cu surface plasmon resonance band at 600 nm. The nanofluid was found to be stable due to high positive zeta potential value, +51 mV. The backscattering level of nanofluid in static stationary was decreased about 2% for 5 days. The thermal conductivity measurement showed that Cu-ethylene glycol nanofluid with low concentration of nanoparticles had higher thermal conductivity than based fluid. The enhancement of thermal conductivity of nanofluid at a volume fraction of 0.1% was approximately 5.2%.

STEP is the international standard for the computer-interpretable representation and exchange of product data. STEP physical file as the implementation method of STEP generally has a large file size which may be an obstacle of efficient use and seamless transition through network. Therefore, the compression of STEP physical file has been interested recently. In this paper, we present the compression algorithm of STEP physical file. STEP physical file is compressed by LZ77 with an appropriate search buffer size for STEP physical file and Huffman coding is applied to the result of LZ77. The proposed algorithm obtains the significant compression ratio.

This study was carried out to investigate the collection Efficiency of mass in collector step at the different of physical gas characterization. This work has focused on the dependence of the collection efficiency of mass in the collector zone of a two-stage set up field with gas temperature T and the dew point tmeperature. To identify the dependence of the mass collection efficiency on the grounded plate of the collector zone M_P,k by the specific electric resistance of dust ρe and the relative humidity φ, 20 attempts have been made with three different gas temperature (50℃, 80℃, 110℃) at different dew point. At the specific electric resistance of dust ρe=10^6Ωm which relative humidity corresponds to φ> 15%, a easy rise of the grounded plate secluded dust mass share was measured again. As the result of the higher cohesion imprisonment power due to the adsorbtion of particle, the rise of the relative humidity developed on the particle surface. Therefore, the collection efficiency of mass was not predominant the high temperature T in the collector zone, neither was the pecific ellectric resistance of dust dependent.