• Journal of Korean Society of Environmental Engineers
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• v.31 no.4
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• pp.241-248
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• 2009

A farming area located near an abandoned copper mine in GuPo-ri, Choongchung province is heavily contaminated with heavy metals such as As, Pb, Cd, Cu and Zn of which concentrations are higher than the values typically detected in Korean soil environment. In this work, laboratory and field studies were conducted to examine feasibility of using Ca-citrate-phosphate solution in stabilizing heavy metals in the polluted soils. In laboratory batch experiments with field soil, the addition of Ca-citrate-phosphate solution resulted in decrease of aqueous phase concentration of phosphate and improvement of heavy metal stabilization, compared to those for sterilized soil samples. This indicates that microbial uptake of phosphate may have provided positive effects on availability of phosphate toward heavy metal stabilization. According to microbial community analysis for the field experiment, the use of Ca-citrate-phosphate led to increased diversity of microbial populations, and strict anaerobic microorganisms such as Anaerofilum and Treponema became the most dominant populations in the solution-amended field experiments. These findings suggest that, when Ca-citrate-phosphate is used for heavy metal stabilization in soils, microbial processes may have important roles in improving the stabilization of heavy metals by providing reducing conditions to the treatment locations or/and by making phosphate available to heavy metal stabilization.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.403-413
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• 2007

As rock bolts become one of the main support systems in tunnels and underground structures, the integrity of the rock bolts affects the safety of these types of structures. The purpose of this study is the evaluation of rock bolt integrity using Fourier and wavelet transforms of the guided ultrasonic waves. After five rock bolt specimens with various defect ratios are embedded into a large scale concrete block, guided waves are generated by a PZT (lead zirconate titanate) element and measured by an acoustic emission (AE) sensor. The captured signals are analyzed in the frequency domain using the Fourier transform, and in the time-frequency domain using the wavelet transform based on a Gabor wavelet. The spectrum obtained from the Fourier transform shows that a portion of high frequency contents increases with increase in the defect ratio. Peak values in the time-frequency domain represent the interval of travel time of each echo. The energy velocities of the guided waves increase with the defect ratio. This study shows that the spectrum ratio and the energy velocity may be indicators fur the evaluation of rock bolt integrity.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.275-281
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• 1996

The objective of the study was to investigate the effects of water treatment sludge (WTS) on the growth of soybean and carrot, and uptake of some inorganic components in the plants. WTS was incorporated to field at the rates of 0, 1, 3, and 5 tons per 10a on the basis of dry weight. With the application of the sludge, OM and CEC in the soil increased slightly while the concentration of available phosphorous decreased. And heavy metals, including Pb, Cd, Cr, As and Hg, were not detected at the harvest stage in crops. With an increase in the application of the sludge, the concentration of phosphorous in the seed of soybean and the root of carrot tended to be decreased. There seems no correlation between rate of application of the sludge and uptake of Al in the plants. The yield of soybean was the highest when applied to one ton sludge and the yield on carrot increased with an increase in rate of applied sludge. Also, the concentration of carotene increased with an increased application of the sludge. But, application of WTS showed to deteriorate the visual quality with an irregularity of carrot's surface. This results indicate that application of WTS will be give a positive and negative effects on soil and crops.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.1
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• pp.33-38
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• 2001

We investigate the via-size dependance of as-electroplated- and reflow-bump shapes for realizing both high-density and high-aspect ratio of solder bump. The solder bump is fabricated by subsequent processes as follows. After sputtering a TiW/Al electrode on a 5-inch Si-wafer, a thick photoresist for via formation it obtained by multiple-codling method and then vias with various diameters are defined by a conventional photolithography technique using a contact alinger with an I-line source. After via formation the under ball metallurgy (UBM) structure with Ti-adhesion and Cu-seed layers is sputtered on a sample. Cu-layer and Sn/pb-layer with a competition ratio of 6 to 4 are electroplated by a selective electroplating method. The reflow-bump diameters at bottom are unchanged, compared with as-electroplated diameters. As-electroplated- and reflow-bump shapes, however, depend significantly on the via size. The heights of as-electroplated and reflow bumps increase with the larger cia, while the aspect ratio of bump decreases. The nearest bumps may be touched by decreasing the bump pitch in order to obtain high-density bump. The touching between the nearest bumps occurs during the overplating procedure rather than the reflowing procedure because the mushroom diameter formed by overplating is larger than the reflow-bump diameter. The arrangement as zig-zag rows can be effective for realizing the flip-chip-interconnect bump with both high-density and high-aspect ratio.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.39-45
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• 2008

Titanium and its alloys are widely used as dental implants materials because of their excellent mechanical properties. However, the alumina and zirconia ceramics are preferred to use as the substitute of Ti implants because there is a problems in esthetics and biocompatibility in Ti implant. The the glass infiltrated alumina ceramics are studied to increase the toughness and biocompatibility. The 45S5 and soda-lime glass powder was mixed with ethanol at ratio of 1:1 and brushed on the surface of alumina. Then it was heat treated in the electric furnace at $1400^{\circ}C$ from 30 min. to 5 hours. The glass powder was controlled from 200 to $350{\mu}m$ using ball milling. After heat treatment, the glass infiltrated specimen was tested in universal testing machine to measure the bending strength. The surface microstructure of each specimen was observed with SEM. The biocompatibility of 45S5 and soda-lime glass coated alumina was investigated using PBS at $36.5^{\circ}C$ incubator. The specimen was immersed in PBS for 3, 5, 7, 10 days. After that, the surface morphology was investigated with SEM. As the results of experiment, the 45S5 bioglass infiltrated alumina show the increase of bending strength according to the increasing of heat treatment time from 30 min. to 5 hours at $1400^{\circ}C$ Finally the 1370N bending strength of alumina increased to 1958N at 5 hours heat treatment, which shows 1.4 times higher. In contrast to this, the soda lime glass infiltrated alumina ceramics shows the convex curve according to heat treatment time. Thus it shows maximum bending strength of 1820N at 1 hour heat treatment of $1400^{\circ}C$ It gives 1.3 times higher. However, the bending strength of soda lime glass infiltrated alumina is decreasing with increasing heat treatment time after 1 hour. The precipitation on the surface of 45S5 glass infiltrated alumina was revealed as a sodium phosphate ($Na_{6}P_{6}O_{24}6H_{2}O$) and the amount of precipitation is increasing with increasing of immersion time in PBS. In contrast to this, there is no precipitation are observed on the surface of soda lime glass infiltrated alumina. This implies that 45S5 glass infiltrated alumina brings more biocompatible when it is implanted in human body.

• Ocean and Polar Research
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• v.24 no.2
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• pp.123-134
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• 2002

Seasonal variations of settling particles and metal fluxes were monitored at a nearshore site of Marian Cove, King Geroge Island, Antarctica from 28th February 1998 to 22nd January 2000. Near-bottom sediment traps were deployed at 30m water depth of the cove, and sampling bottles were recovered every month by SCUBA divers. Total particulate flux and metal concentrations were determined from the samples. Total particulate flux showed a distinct seasonality, high in austral summer and low in austral winter: the highest flux $(21.97g\;m^{-2}d^{-1})$ was found in February of 1999, and the lowest $(2.47g\;m^{-2}d^{-1})$ in September of 1998, when sea surface was frozen completely. Lithogenic particle flux accounted for 90% of the total flux, and showed a significantly negative correlation with the thickness of snow accumulation around the study site. It was suggested that the most of the lithogenic particles trapped in the bottles was transported by melt water stream from the surrounding land. Fluxes of Al, Fe, Ti, Mn, Zn, Cii, Co, Ni, Cr, Cd, and Pb showed similar seasonal variations with the total flux, and their averaged fluxes were 34000, 9000,960, 180, 13.8, 17.6, 3.0,2.1, 5.4, 0.02, and $1.5nmol\;m^{-2}d^{-1}$ respectively. Among the metals, Cu and Cd showed the most noticeable seasonal patterns. The Cd flux correlated positively with the fluxes of biogenic components while the Cu flux correlated with both the lithogenic and biogenic particle fluxes. The Cu flux peak in the late summer is likely related to a substantial amount of inflow of ice melt water laden with Cu-enriched lithogenic particles. On the other hands, the Cd flux peak in the early spring may be associated with the unusually early occurred phytoplankton bloom.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.4
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• pp.613-618
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• 1995

This study was carried out to investigate the effect of extracting pH on the components and color of seasame protein concentrate(SPC). The protein contents of SPC by extracted at pH 2.0, 7.0, 9.0 and 11.0 were 60.57, 67.72, 79.50 and 83.44%, respectively. Most of the phytates were removed in SPC extracted at pH 7.0, 9.0 and 11.0, but the phytate content of SPC extracted at pH 2.0 was about the same as that of defatted sesame flour. The highest decrease of phytate was found in SPC extracted at pH 11.0(94.80%). SPC extracted at pH 2.0 contained the highest amount of Ca, Mg, Fe and Zn than those in other SPC prepared, while highest amount of Cu was found in SPC extracted at pH 11.0. Sodium content was similar among all the SPC prepared. SPC extracted at pH 7.0 resulted in brighter clor, but SPC extracted at pH 11.0 showed a little darker in appearance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.106-117
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• 2006

We measured the concentrations of organic matter and metallic elements (Al, Fe, Cr, Mn, Ni, Cu, Zn, As, Cd, Pb and Hg) in the surface sediments of Masan Harbor (in the southern sea, Korea) to evaluate the geochemical characters of sediment and the pollutions by organic matter and metallic elements. The mean grain size of the surface sediments in the study area ranged from $5.6{\phi}$ to $7.8{\phi}$, indicating silt sediment. The water content of the surface sediments exceeded 60% except at some stations. The contents of ignition loss (IL), total organic carbon (TOC) and total nitrogen (TN) ranged from 7.2-14.3%, 1.2-3.2%, and 0.10-0.28%, respectively. Based on the C/N ratios, the organic matter in the surface sediments of Masan Harbor may originate from terrigenous sources including fluvial inputs (mainly sewage in urban areas). The chemical oxygen demand (COD) and acid volatile sulfide (AVS) ranged from $11.3-29.9\;mgO_2/g\;dry$ and 0.20-4.47 mgS/g dry, respectively, and low concentrations were observed near a shipping route. In addition, the concentrations of metallic elements showed large spatial variations in Masan Harbor and the distributions of metallic elements were also comparable to those of organic matter. This implies that the distributions of organic matter and metallic elements in the surface sediments of Masan Harbor are mainly controlled by biogenic matter and artificial action (mainly dredging). In addition, we calculated the enrichment facto. (EF) and geoaccumulation index (Igeo) in order to evaluate pollution by metallic elements. The enrichment of metallic elements relative to Al was three to eighteen times higher at the study sites, compared to levels in the Earth's crust except for Fe, Ni and Mn. In addition, the Igeo class indicated that the surface sediments in the study area were moderately to strongly polluted in terms of metallic elements.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.518-524
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• 2010

A mannanase gene (man26B) was obtained from a sea bacterium, Paenibacillus sp. BME-14, through the constructed genomic library and inverse PCR. The gene of man26B had an open reading frame of 1,428 bp that encoded a peptide of 475- amino acid residues with a calculated molecular mass of 53 kDa. Man26B possessed two domains, a carbohydrate binding module (CBM) belonging to family 6 and a family 26 catalytic domain (CD) of glycosyl hydrolases, which showed the highest homology to Cel44C of P. polymyxa (60% identity). The optimum pH and temperature for enzymatic activity of Man26B were 4.5 and $60^{\circ}C$, respectively. The activity of Man26B was not affected by $Mg^{2+}$ and $Co^{2+}$, but was inhibited by $Hg^{2+},\;Ca^{2+},\;Cu^{2+},\;Mn^{2+},\;K^+,\;Na^+$, and $\beta$-mercaptoethanol, and slightly enhanced by $Pb^{2+}$ and $Zn^{2+}$. EDTA did not affect the activity of Man26B, which indicates that it does not require divalent ions to function. Man26B showed a high specific activity for LBG and konjac glucomannan, with $K_m,\;V_{max}$, and $k_{cat}$ values of 3.80 mg/ml, 91.70 ${\mu}mol$/min/mg protein, and 77.08/s, respectively, being observed when LBG was the substrate. Furthermore, deletion of the CBM6 domain increased the enzyme stability while enabling it to retain 80% and 60% of its initial activity after treatment at $80^{\circ}C$ and $90^{\circ}C$ for 30 min, respectively. This finding will be useful in industrial applications of Man26B, because of the harsh circumstances associated with such processes.

• Analytical Science and Technology
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• v.23 no.3
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• pp.284-294
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• 2010

In this study, river water-based reference materials (RMs), NIER-I08RW and NIER-I09, for trace metal analysis were prepared and certified for Pb, Cd, Cr and Cu with evaluation of uncertainties. The RMs were confirmed to be homogeneous enough to be used as proficiency testing materials since within-bottle homogenieties of the RMs were lower than 0.3 times of targeted standard deviation of proficiency testing. The RMs were distributed to environmental testing laboratories for the proficiency testing and the variation of Z scores of the proficiency testing results were compared for different assigned values. The relative bias, $B_{relative}$, deviations between reference values and consensus values, were lower than ${\pm}$1 except for cadmium of NIERI08RW. The results showed both values were in a good agreement and only 2.9% of Z scores changed by using a different assigned values such as consensus and reference values.