• Korean Journal of Materials Research
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• v.11 no.7
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• pp.556-561
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• 2001

We prepared a new a SOS(silicon-on-silicide) wafer pair which is consisted of Si(100)/1000$\AA$-NiSi Si (100) layers. SOS can be employed in MEMS(micro- electronic-mechanical system) application due to low resistance of the NiSi layer. A thermally evaporated $1000\AA$-thick Ni/Si wafer and a clean Si wafer were pre-mated in the class 100 clean room, then annealed at $300~900^{\circ}C$ for 15hrs to induce silicidation reaction. SOS wafer pairs were investigated by a IR camera to measure bonded area and probed by a SEM(scanning electron microscope) and TEM(transmission electron microscope) to observe cross-sectional view of Si/NiSi. IR camera observation showed that the annealed SOS wafer pairs have over 52% bonded area in all temperature region except silicidation phase transition temperature. By probing cross-sectional view with SEM of magnification of 30,000, we found that $1000\AA$-thick uniform NiSi layer was formed at the center area of bonded wafers without void defects. However we observed debonded area at the edge area of wafers. Through TEM observation, we found that $10-20\AA$ thick amourphous layer formed between Si surface and NiSix near the counter part of SOS. This layer may be an oxide layer and lead to degradation of bonding. At the edge area of wafers, that amorphous layer was formed even to thickness of $1500\AA$ during annealing. Therefore, to increase bonding area of Si NiSi ∥ Si wafer pairs, we may lessen the amorphous layers.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.180-185
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• 2003

The increase of traffic over a bridge has been emerged as one of the most severe problems in view of bridge maintenance, since the load effect caused by the vehicle passage over the bridge has brought out a long-term damage to bridge structure, and it is nearly impossible to maintain operational serviceability of bridge to user's satisfactory level without any concern on bridge maintenance at the phase of completion. Moreover, bridge maintenance operation should be performed by regular inspection over the bridge to prevent structural malfunction or unexpected accidents front breaking out by monitoring on cracks or deformations during service. Therefore, technical breakthrough related to this uninterested field of bridge maintenance leading the public to the turning point of recognition is desperately needed. This study has the aim of development on automated inspection system to lower surface of bridge superstructures to replace the conventional system of bridge inspection with the naked eye, where the monitoring staff is directly on board to refractive or other type of maintenance .vehicles, with which it is expected that we can solve the problems essentially where the results of inspection are varied to change with subjective manlier from monitoring staff, increase stabilities in safety during the inspection, and make contribution to construct data base by providing objective and quantitative data and materials through image processing method over data captured by cameras. By this system it is also expected that objective estimation over the right time of maintenance and reinforcement work will lead enormous decrease in maintenance cost.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.820-825
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• 2007

Earthworm casting was the natural fertilizer that contained high concentrations of nutrients such as nitrogen, phosphate and potassium and of over $10^8$ CFU/ml of microorganisms. Greater than 80% of feed was excreted through the fermentation by the intestinal enzyme, after worm had eaten feeds such as fallen leaves and rotten roots under the ground. Also, the soil structure of casting was known to be very efficient in the aspects of the porosity, the water permeability, and deodorizing activities. In this research, the biofilter packed with a biomedia made of casting and waste polyurethane foam, a binder, which helped to improve the durability and perpetuity of casting, was investigated to degrade malodorous hydrogen sulfide gas. The biomedia had no need of extra supply of nutrients and of microbial inoculations. On the beginning of the operations, it showed 100% removal of hydrogen sulfide gas without lag phase. At SV of 50 $h^{-1}$, hydrogen sulfide gas from the outlet of the biofilter was not detected, when inlet concentration increased to 450 ppmv. After that, removal efficiency decreased as increasing inlet hydrogen sulfide concentration. Hydrogen sulfide removal was maintained at almost 93% until inlet concentration was increased up to 950 ppmv, at which the elimination capacity of $H_2S$ was 61.2 g $S{\cdot}m^{-3}{\cdot}h^{-1}$. Maximum elimination capacity guaranteing 90% removal was 61.2, 65.9, 84.7, 89.4 g $S{\cdot}m^{-3}{\cdot}h^{-1}$ at SV ranging from 50 $h^{-1}$ to 300 $h^{-1}$, but was 59.3 g $S{\cdot}m^{-3}{\cdot}h^{-1}$ at SV of 400 $h^{-1}$. The results calculated from Michaelis-Menten equation revealed that $V_m$ increased from 66.04, 88.96, 117.35, 224.15, to 227.54 g $S{\cdot}m^{-3}{\cdot}h^{-1}$ with increasing space velocity in the range of 50 $h^{-1}$ to 400 $h^{-1}$. However, saturation constant$(K_s)$ decreased from 79.97 ppmv to 64.95 and 65.37 ppmv, and then increased to 127.72 and 157.43 ppmv.

• Journal of Dairy Science and Biotechnology
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• v.33 no.4
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• pp.263-269
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• 2015

Various carbohydrates (lactose, glucose, and fructose), lactic acid, uric acid, and acetoin were separated on a ZORBAX Carbohydrate Analysis column using the Agilent 1200 HPLC ChemStation$^{TM}$, and were identified according to retention times with 325 Dual Wavelength UV-Vis Detector and Refractive Index Detector with 0.013 N $H_2SO_4$ at a flow rate of 0.8 mL/min. In addition, the lactase activity of four commercial probiotic lactic acid bacteria during 6-hour incubation was determined using a high-performance liquid chromatography (HPLC) method. Among the tested samples, Bifidobacterium animalis subsp. lactis showed the greatest lactase activity, followed by Lactobacillus rhamnosus and Lactobacillus casei, with Streptococcus salivarius subsp. thermophilus showing the lowest activity. Therefore, this HPLC technique shows potential for evaluating the fermentation processes of probiotic lactic acid bacteria and could simultaneously confirm the degree of ripening in various fermented dairy foods within only a half hour.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.420-430
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• 2005

This study was performed to change the hydrophilic $NH_4Y$-zeolite to the hydrophobic one for removal of VOCs by removing the $Al^{3+}$ in the zeolite-structure to increase the Si/Al ratio, for which the three pelleted $NH_4Y$-zeolite samples were contacted separately with the steam of $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$, respectively, in a stainless steel column for 4 hours. Then extraction of the ex-structure aluminum of the hydrolyzed zeolites with the nitric acids of 0.25, 0.50, 0.75, and 0.10 M at $90^{\circ}C$ in 500 mL-flasks, respectively, according to steam temperature were followed. XRD analysises of the dealuminated zeolites showed that the peaks of the zeolites that had been hydrolyzed with the steams of both $500^{\circ}C$ and $600^{\circ}C$ are distorted more with the increase of the concentration of nitric acid used for extraction of the ex-structure aluminums, however, those hydrolyzed with steam of $400^{\circ}C$ became amorphous phase when treated with the all nitric acids of four concentrations. Also the EDX analysises showed that the BET surface areas and TPVS of the zeolites that had been hydrolyzed with the steam of $600^{\circ}C$ were increased with the concentration of the nitric acid when the nitric acids of 0.25 M and 0.5 M had been used but decreased when the nitric acids of 0.75 M and 1.0 M had been used. These results led to the conclusion that both the $600^{\circ}C$ and $500^{\circ}C$-steam and the 0.5 M-nitric acid are appropriate to change the hydrophilic $NH_4Y$-zeolites to the hydrophobic one, which were proven by the measurement of the benzene and tolune-adsorbing capacities showing the same trend as the BET surface area and TPV The Si/Al ratios and water-adsorbing capacities of the dealuminated zeolites were increased and decreased, respectively, with the concentration of the nitric acids so that it showed that the hydrophobicity is increased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.1-6
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• 1981

In this study, sesame oil was chosen as the experimental sample and analysed for its triglyceride composition by high-performance liquid chromatography(HPLC) in combination with gas liquid chromatography(GLC). The triglycerides were separated from sesame oil by liquid chromatographies on Bio-Beads SX-2 and on Sephadex LH-20, and fractionated into five groups on the basis of their partition numbers by reverse phase HPLC on a column packed with $\mu-Bondapak$ C18 using methanol-chloroform mix-ture as a solvent. Each of these collected fractions gave one to three peaks in the GLC chromatograms according to the acyl carbon number of the triglyceride, and fatty acid composition of the triglyceride was also analysed by GLC. From the results, it was found that the sesame oil consists with twenty one kinds of triglyceri-des, and the major triglycerides of sesame oil are those of $(2\;{\times}\;C18:1,\;C18:2\;;\;17.1\%),\;(C18:1,\;2{\times}C18:2\;;\;17.0\%),$ $(3\;{\times}\;C18:2\;;\;17.0\%),\;(3\;{\times}\;C18:1\;;\;10.9\%),$ $(3\;{\times}\;C18:2\;;\;9.6\%),\;(C16:0,\;C18:1,C18:2\;;\;7.9\%),$ $(C16:0,\;2\;{\times}\;C18:1\;;\;7.4\%),\;(C16:0,\;2\;{\times}\;C18:2\;;\;6.8\%),$ $(C18:0,\;C18:1,\;C18:2\;;\;3.1\%),\;(2\;{\times}\;C18:0,\;C18:2\;;\;1.5\%)$ $(C18:0,\;2\;{\times}\;C18:1\;;\;1.4\%),\;(C16:0,\;C18:0,\;C18:1\;;\;1.3\%),$ $(2\;{\times}\;C16:0,\;C18:1\;;\;1.2\%),\;and\;(C16:0,C18:0,\;C18:2\;;\;1.0\%)$.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.425-438
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• 2009

We reevaluate the Burton equation (Burton et al. 1975) of predicting Dst index using high quality hourly solar wind data supplied by the ACE satellite for the period from 1998 to 2006. Sixty magnetic storms with monotonously decreasing main phase are selected. In order to determine the injection term (Q) and the decay time ($\tau$) of the equation, we examine the relationships between $Dst^*$ and $VS_s$, ${\Delta}Dst^*$ and $VS_s$, and ${\Delta}Dst^*$ and $Dst^*$ during the magnetic storms. For this analysis, we take into account one hour of the propagation time from the ACE satellite to the magnetopause, and a half hour of the response time of the magnetosphere/ring current to he solar wind forcing. The injection term is found to be $Q(nT/h)\;=\;-3.56VS_s$ for $VS_s$ > 0.5mV/m and Q(nT=h) = 0 for $VB_s\;{\leq}\;0.5mV/m$. The $\tau$ (hour) is estimated as $0.060Dst^*\;+\;16.65$ for $Dst^*$ > -175nT and 6.15 hours for $Dst^*\;{\leq}\;-175nT$. Based on these empirical relationships, we predict the 60 magnetic storms and find that the correlation coefficient between the observed and predicted $Dst^*$ is 0.88. To evaluate the performance of our prediction scheme, the 60 magnetic storms are predicted again using the models by Burton et al. (1975) and O'Brien & McPherron (2000a). The correlation coefficients thus obtained are 0.85, the same value for both of the two models. In this respect, our model is slightly improved over the other two models as far as the correlation coefficients is concerned. Particularly our model does a better job than the other two models in predicting intense magnetic storms ($Dst^*\;{< \atop \sim}\;-200nT$).

• Radiation Oncology Journal
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• v.23 no.3
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• pp.131-136
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• 2005

Purpose: The aim of this study was to evaluate the clinical results of postoperative radiotherapy for parotid gland malignancy, and determine prognostic factors for locoregional control and survival. Materials and Methods: Between 1980 and 2002, 130 patients with parotid malignancy were registered In the database of the Department of Radiation Oncology, Seoul National University Hospital. The subjects of this analysis were the 72 of these 130 patients who underwent postoperative Irradiation, There were 42 males and 30 females, with a median age of 46.5 years. The most common histological type was a mucoepidermoid carcinoma. There were 6, 23, 23 and 20 patients in Stages I, II, III and IV, respectively. The median dose to the tumor bed was 60 Gy, with a median fraction size of 1.8 Gy. Results: The overall 5 and 10 year survival rates were 85 and $76\%$, respectively, The five-year locoregional control rate was $85\%$, which reached a plateau phase after 6 years. Sex and histological type were found to be statistically significant for overall survival from a multivariate analysis. No other factors, Including age, facial nerve palsy and stage, were related to overall survival. For locoregional control, nodal involvement and positive resection margin were associated with poor local control. Histological type, tumor size, perineural invasion and type of surgery were not significant for locoregional control. Conclusion: A high survival rate of parotid gland malignancies, with surgery and postoperative radiotherapy, was confirmed. Sex and histological type were significant prognostic factors for overall survival. Nodal Involvement and a positive resection margin were associated with poor locoregional control.

• Journal of the Korean Magnetics Society
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• v.14 no.1
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• pp.46-50
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• 2004

Compounds of $Y_{3-x}Ce_{x}Fe{5}O_{12}$(x=0.0, 0.1, 0.2, and 0.3) were prepared using the sol-gel method. The XRD measurements show that these samples have only a single phase of the garnet structure regardless of the amount of Ce substitution. The lattice constants of x = 0.0 and x = 0.3 were found to be a$_0$ = 12.3758 ${\pm}$0.0005 ${\AA}$ and 12.4062 ${\pm}$0.0005 ${\AA}$, respectively. The lattice constant increases linearly with increasing Ce concentration. The saturation magnetization was not changed flirty, with increasing Ce concentration, but coercivity decreased form 18.3 Oe to 5.8 Oe as x increased form x = 0.0 to x = 0.1. Mossbauer spectra of $Y_{3-x}Ce_{x}Fe{5}O_{12}$ were measured at various absorber temperatures from 13 K to Neel temperature. The Mossbauer spectra were fitted by least-squares technique with two subpatterns of Fe sites in the structure and corresponding to the 16a and 24d site. The temperature dependence of the magnetic hyperfine field in $^{57}$/Fe nuclei at the tetrahedral 240 and octahedral 16a sites were analyzed based on the Neel theory of ferrirnagnetism. The result of the Debye temperatures indicated that the inter-atomic binding force for the 24d site was larger than that for the 16a site.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.3
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• pp.169-175
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• 2012

Purpose: In this study, brazing characteristics of $ZrO_2$ and Ti-6Al-4V brazed joints with increasing temperature were investigated. Materials and methods: The sample size of the $ZrO_2$ was $3mm{\times}3mm{\times}3mm$ (thickness), and Ti-6Al-4V was $10mm(diameter){\times}5mm(thickness)$. The filler metal consisted of Ag-Cu-Sn-Ti was prepared in powder form. The brazing sample was heated in a vacuum furnace under $5{\times}10^{-6}$ torr atmosphere, while the brazing temperature was changed from 700 to $800^{\circ}C$ for 30 min. Results: The experimental results shows that brazed joint of $ZrO_2$ and Ti-6Al-4V occurred at $700-800^{\circ}C$. Brazed joint consisted of Ag-rich matrix and Cu-rich phase. A Cu-Ti intermetallic compounds and a Ti-Sn-Cu-Ag alloy were produced along the Ti-6Al-4V bonded interface. Thickness of the reacted layer along the Ti-6Al-4V bonded interface was increased with brazing temperature. Defect ratios of $ZrO_2$ and Ti-6Al-4V bonded interfaces decreased with brazing temperature. Conclusion: Thickness and defect ratio of brazed joints were decreased with increasing temperature. Zirconia was not wetting with filler metal, because the reaction between $ZrO_2$ and Ti did not occur enough.