• Journal of Environmental Science International
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• v.8 no.3
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• pp.271-280
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• 1999

This study was carried out to investigate the characteristics of acidity in the precipitation and weather patterns that were influenced it at Kimhae area from March, 1992 to June, 1994. The range of pH value in the precipitation at Kimhae is 3.45 to 6.80 and the average is pH 4.62, and the major anion components associated with acidity in the precipitation are $Cl^-, SO_4^{-2}, NO_3^-$. These distributions are to be expected the influence of industrialization such as, urbanization and construction of industrial complex at Kimhae area and the long range trasporting of air pollutants from China. The weather patterns governing the acid rain at Kimhae were classified broadly into four types(Cyclone(type I-a, type I-b), Migratory Anticyclone(type II), Tropical Cyclone(type III), Siberia High(type IV) and weather pattern which had the most occurrence frequency of acid rain was type I-a and the average pH value of precipitation in this pattern was 4.45, and we are found that the source area of air mass which was accompanied with high acidic precipitation in Kimhae was the central China include with Peking through the analysis of surface weather maps, 850 hPa wind fields, and the streamline analyses.

• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.23-28
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• 1997

The adsorption characteristics of ammonia-Cu(II) complex on activated carbon were studied. Firstly, the specific surface area of the activated carbon was measured by using the BET adsorption apparatus. Secondly, the characteristics of the removal copper(II) ion from aqueous ammonia solution by forming a complex with ammonia and then by the adsorption of the complex on the activated carbon were studied. It was found that the specific surface area increases with decreasing the mesh number of the activated carbon, and the optimum pH for the adsorption of the Cu(II) ion on she activated carbon was found to be approximately 6. It was also found that the adsorbed Cu(II)-ammonia complexes on the activated carbon in the aqueous ammonia solution have two types, depending on the concentration of the solution ; i.e. $[Cu(NH_3){_2}]^{2+}$and $[Cu(NH_3){_3}]^{2+}$ for $2.25{\times}10^{-4}(mol/{\ell})$and $2.25{\times}10^{-3}(mol/{\ell})$, respectively.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.154-159
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• 1999

EDTA (ethylenediaminetetraacetic acid), a chelating agent is most widely used in industrial applications, especially for cleaning of metals in water, frequently prohibits metal removal from water in conventional water treatment technologies. It could be easier to remove aqueous metal ions by the breakdown of DETA complexed bonds first. This study investigated the availability of $TiO_2$ photo-catalysis for the aqueous phase oxidation of Cu(II)-EDTA, under an aerobic condition at $20^{\circ}C$ with $TiO_2$ (Degussa P-25) and 1.79mM of Cu(II)-EDTA. When $TiO_2$ loading was 2.0 g/L, the photo-catalytic oxidation of Cu(II)-EDTA was maximal. The tendency of EDTA adsorption onto the catalyst surface was affected by $TiO_2$ surface charge, and the oxidation rate of Cu(II)-EDTA by photo-catalysis was shown to be dependent upon the tendency of EDTA adsorption before photo-irradiation.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.43.4-44
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• 2016

We observed the high resolution spectra of a solar-neighborhood planetary hosting star HD 20794. The analysis of spectroscopic data was performed using URAN and SYNTHE programs. These spectra allow us to determine the effective temperatures, surface gravities, microturbulent velocities and, chemical abundances. Bond et al. (2008) found chemical abundance for 11 elements, but using the Spectrum synthesis method we have so far determine about 30 elements. We have derived iron metallicity $[FeI/H]=-0.42{\pm}0.03$, $[FeII/H]=-0.43{\pm}0.012$, and surface gravity, log g = 4.48, in good agreement with values from previous investigation.

• Journal of the Korean institute of surface engineering
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• v.5 no.2
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• pp.1-4
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• 1972

We have studied about the optimum chemical etching and sensitizing conditions of the plating on plastics. As specimen 'Mitzubishi Nobren MM2A' was used. The results were as follow. 1) The optimum chemical etching conditions. Etched the specimens for $10{\sim}40$ minutes at $70{\sim}80^{\circ}C$ with the etching solution of table 1, and for $10{\sim}15$ minutes at $65{\sim}70^{\circ}C$ with the etching solution of table 2 Table 1. Etching solution (I) Composition : $H_2SO_4(95%)-Component : 250 ml, Composition : $H_3PO_4(85%)$ - Component : 75ml, Composition : $K_2Cr_2O_7$ - Component : 12.5g, 2) The optimum sensitizing conditions. Sensitized the specimens for $60{\sim}90$ seconds at $25^{\circ}C$ with the sensitizing solution of table 3 Table 2. Etching solution (II) Composition : $H_2SO_4(95%)$ - Component : 22.5ml, Composition : $H_3PO_4(85%)$ - Component : 15ml, Composition : $CrO_3$ - Component : 105g, Composition : Water - Component : 150 ml, Table 3. Sensitizing solution Composition : $SnCl_2$ - Component : 9g, Composition : HCl(35%) - Component : 36ml, Composition : Water - Component : 300 ml

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.2
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• pp.204-216
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• 1999

Failure physics and statistical lifetime analysis constitute the two extreme ends of the reliability engineering spectrum, and studies that relate failure mechanisms to failure distributions have been near non-existent. This paper is an attempt to stimulate interest to fill the gap between the two extremes and proposes an approach of combining them through i) developing a failure mechanism model, ii) generating failure times by Monte Carlo simulation with the model, iii) deriving the failure time distribution and evaluating the product reliability, and iv) improving the product reliability by the sensitivity analysis. An application of the proposed approach to the BGA(Ball Grid Array) surface mount package is also provided.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.3
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• pp.194-201
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• 2010

Purpose: The purpose was to compare the marginal fidelity and the fracture resistance of the zirconia crowns according to the various coping designs with different thicknesses and cement types. Materials and methods: Zirconia copings were designed and fabricated with various thicknesses using the CAD/CAM system (Everest, KaVo Dental GmbH, Biberach., Germany). Eighty zirconia copings were divided into 4 groups (Group I: even 0.3 mm thickness, Group II: 0.3 mm thickness on the buccal surface and the buccal half of occlusal surface and the 0.6 mm thickness on the lingual surface and the lingual half of occlusal surface, Group III: even 0.6 mm thickness, Group IV: 0.6 mm thickness on the buccal surface and the buccal half of occlusal surface and the 1.0 mm thickness on the lingual surface and the lingual half of occlusal surface) of 20. By using a putty index, zirconia crowns with the same size and contour were fabricated. Each group was divided into two subgroups by type of cement: Cavitec$^{(R)}$ (Kerr Co, USA) and Panavia-$F^{(R)}$ (Kuraray Medical Inc, Japan). After the cementation of the crowns with a static load compressor, the marginal fidelity of the zirconia crowns were measured at margins on the buccal, lingual, mesial and distal surfaces, using a microscope of microhardness tester (Matsuzawa, MXT-70, Japan, ${\times}100$). The fracture resistance of each crown was measured using a universal testing machine (Z020, Zwick, Germany) at a crosshead speed of 1 mm/min. The results were analyzed statistically by the two-way ANOVA and oneway ANOVA and Duncan's multiple range test at $\alpha$=.05. Results: Group I and III showed the smallest marginal fidelity, while group II demonstrated the largest value in Cavitec$^{(R)}$ subgroup (P<.05). For fracture resistance, group III and IV were significantly higher than group I and II in Cavitec$^{(R)}$ subgroup (P<.05). The fracture resistances of Panavia-$F^{(R)}$ subgroup were not significantly different among the groups (P>.05). Panavia-$F^{(R)}$ subgroup showed significantly higher fracture resistance than Cavitec$^{(R)}$ subgroup in group I and II (P<.05). Conclusion: Within the limitation of this study, considering fracture resistance or marginal fidelity and esthetics, a functional ceramic substructure design of the coping with slim visible surface can be used for esthetic purposes, or a thick invisible surface to support the veneering ceramic can be used depending on the priority.

• Publications of The Korean Astronomical Society
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• v.18 no.1
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• pp.75-79
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• 2003

The characteristics of the BOES (Bohyunsan Observatory Echelle Spectrograph) CCD camera is presented. In order to get optimum gain and readout noise of the CCD, we examine the variation of the gain and readout noise by changing the value of output drain voltage of the CCD and measuring the gain using transfer curve, which is defined as the plot of variance versus mean exposure level of a homogeneous light onto the CCD surface. The gain and readout noises are optimised to be 0.5e$^-$/ADU and 3e$^-$, which is good for highest signal-to-noise ratio and contrast for the low light level characteristics of the BOES. We also measure the dark count of the CCD by getting five dark images with 3600 seconds exposure time. The mean dark count from median stacked dark images is essentially zero. A table of positions of defected pixels is also presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.93-93
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• 2009

In order to overcome the lack of reactivity with hydrogen gas ($H_2$) and utilize unique properties of Carbon Nano Tubes (CNTs) for the application to hydrogen sensors, there have been intensive works on the surface functionalization of CNTs with various types of nanoparticles including Pd. In the present work, we have investigated the effect of dendrimers and Pd nanoparticles to the hydrogen sensing properties of CNTs by comparing three types of samples: Pd/SWNTs (Sample I), Pd/dendrimer/SWNTs (Sample II) and heat-treated Pd/dendrimers/SWNTs (Sample III). As a result of IV measurement under the $H_2$ and air, sample I was found to have a high sensitivity (25%) to $H_2$, but to have a very slow response time (324 s) and recovery rate. On the other hand, Sample II was found to show much faster response time (3 s) and good recovery rate but lower sensitivity (8.6%) than Sample I which is due to induced dipole moments in the dendrimers. Interestingly, Sample III showed both fast response time (7 s) and high sensitivity (25%), indicating that the pyrolysis of the dendrimers during heat treatment which reduce the distance between the surface of the SWNTs and the functionalized Pd nanoparticles plays a key role in improving the sensitivity. The pyrolysis of the dendrimers in Pd nanoparticle-dendrimer-SWNTs was found to enable a significant electrical conductance modulation upon exposure to extremely low concentrations (10 ppm) of $H_2$ in air. Our results demonstrate that the Pd Nanoparticle-Grafted Single-Walled Carbon Nanotubes(SWNTs) with Dendrimers can be used to detect hydrogen, makingoutstanding properties such as fast response, and recovery time, high sensitivity, low detection limit at room temperature compared with other types of hydrogen sensors.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.45-64
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• 1993

This paper dealt with the application of a numerical method developed by the authors using the matching method proposed in the previous paper on "The Nonlinear motions of cylinders(I)[16]", and Cauchy's theorem to the problems associated with hydrodynamic forces acting on a heaving cylinders translating in a calm water and also motions of cylinders in waves. In spectral method. body boundary condition in submerged case is satisfied exactly but one in floating case is not satisfied exactly. In the numerical code developed here, the boundary condition at the free-surface and body surface is satisfied exactly at its instaneous position. It is of interest to note that the present scheme could be applied to a free-surface-piercing body without experiencing a difficulty in the numerical convergence. The computed results are compared with other results([6], [12]).