The critical loads of sulfur and nitrogen and their exceedances by the sulfur and nitrogen deposition of 1994-1998 were mapped for South Korea for the first time with a spatial resolution of 11km×14km (0.12 5° Long.×0.125° Lat.) using the steady-state mass balance model. The Korean soil and geological maps with the map scale of 1: 250, 000 and the Korean forestry statistical yearbooks were used as basis for the estimations of weathering rate of base cations, critical alkalinity leaching, denitrification fraction and uptakes of base cation and nitrogen. Wet depositions of sulfur, nitrogen and non-sea-salt base cations were derived from measured concentrations in precipitation and precipitation rates using optimum regression equations while dry depositions of sulfur and base cations were estimated using the inferential method. However, dry deposition of nitrogen due to NO, NO₂, NH₃ and NH₄⁺ species was estimated using the MM5 numerical model, a modified Regional Acid deposition Model (RADM) and the K-mean clustering technique using three consecutive days of gridded daily mean 850 hPa geopotential height fields without precipitation on the last day over South Korea for 5 years. The predominant ranges of base cation deposition, weathering and uptake were estimated to be 300-500 eq ha^-1 yr^-1, 200-500 eq ha^-1 yr^-1 and 200-400 eq ha^-1 yr^-1, respectively. Critical alkalinity leaching was mainly in the range of 1, 0002, 000 eq ha^-1 yr^-1. Consequently, a large percentage of the maximum critical load of sulfur was found to be in the range of 1, 0002, 000 eq ha^-1 yr^-1. The estimated predominant ranges of nitrogen immobilization and uptake were 120-180 eq ha^-1 yr^-1 and 300-400 eq ha^-1 yr^-1, respectively, indicating low values of the minimum critical load of nitrogen. The maximum critical load of nitrogen was found to be relatively high (predominantly 2, 0004, 000 eq ha^-1 yr^-1) while the critical load of nutrient nitrogen was low (predominantly 400-800 eq ha^-1 yr^-1). Exceedance of the maximum critical load of sulfur was found at 85% of the Korean ecosystems considered mainly in the southeastern part of Korea, whereas that of the critical load of nutrient nitrogen was found in the whole Korean ecosystems. This implies that Korean ecosystems are very susceptible to the combined loadings of sulfur and nitrogen.

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Alloys of Bi₂Te₃ rich side of Bi2Te3-Bi2Se3 were prepared by the zone melting method and the hot pressing method in order to compare their thermoelectric properties. When specimens were hot pressed thermoelectric properties changed as a function of particle size, pressing time and hot pressing temperature. The reasons for the variation of the thermoelectric properties were investigated by examining influences of following parameters; oxidation, mechanical deformation during pulverization and the hot pressing temperature. Thermoelectric properties of zone melted ingot were largely affected by dopants when composition is fixed, whereas thermoelectric properties of hot pressed material were mainly related with the variation of the carrier concentrations caused by the generation of electrically active defects from many sources. Defects induced by the mechanical deformation and oxygen causes generation of donors. Defect concentration is also altered with different hot pressing temperatures depending on the amount of previously received mechanical deformation.

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The active sites for selective oxidation can be synthesized on polyoxometalates (oxide clusters). For example, Keggin-type di-iron-substituted silicotungstate, γ-SiW₁₀ {Fe (OH₂)} ₂0₃₈^6- (I), was synthesized by the reaction of the lacunary γ-SiW₁₀O₃₆^8-with Fe (NO₃) ₃, in an acidic aqueous solution and isolated as the tetra-n-butylammonium salt (TBA-I). It was characterized by various analyses and the structure with the oxo-bridged di-iron site was clarified. TBA- I was stable and catalyzed selective oxidation of various alkanes and alkenes with hydrogen peroxide: Cyclohexane, adamantane, n-hexane, and n-pentane were catalytically oxidized. Even lower alkanes such as methane, ethane, propane, and n-butane were catalytically oxidized. It was remarkable that the efficiency of hydrogen peroxide utilization to oxygenated products reached up to ca. 100% for the oxidation of cyclohexane and adamantane. Alkenes were mainly epoxidized with hydrogen peroxide. In addition, it was demonstrated that the TBA-I showed high turnover numbers for the oxygenation of cyclohexane and epoxidation of alkenes with 1 atm oxygen.

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Thermal reactions of sputtered Cu films on the fluorinated silicon oxide (FSG) and organosilicate glass (OSG) layers, with and without TiN or TaN diffusion barrier, were investigated. The sheet resistance, surface morphology, phase formation and compositional depth profile of the mutilayer structures after vacuum annealing at 400 to 800°C were examined. It is found that the sheet resistance values of all samples decreased after annealing at 400 to 600°C and increased after annealing at 700 or 800°C. Without the barrier layer, the increase of sheet resistance was accompanied with the dewetting of Cu films and the carbon outdiffusion for Cu/OSG sample or the Cu indifftision of the Cu/FSG sample. When a TiN/Ti or a TaN/Ta barrier layer was interposed between Cu and the dielectric layer, the degree of dewetting of Cu film was significantly reduced for both systems. The reaction characteristics of the two dielectric systems unon vacuum annealing with and without the barrier laverare discussed.

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The mechanical properties and the joint strength of Sn-Ag-Bi solders as replacement solders for Sn-Pb eutectic solder were investigated. The joint strength between Cu sheets and solder decreases when more than 5 mass% Bi is added to Sn-Ag system solders after annealing. Zn addition to Sn-3Ag-5Bi solder is carried out in order to improve the joint strength. The effect of Zn addition to Sn-3Ag-5Bi solder on the joint strength and the joint interface structure was investigated. Zn addition to Sn-3Ag-5Bi solder changes the joint interface structure from solder/Cu-Sn intermetallic compounds/Cu to solder/Cu-Zn intermetallic compound/Cu-Sn intermetallic compound/Cu. Cu-Zn intermetallic compound acts as a barrier layer for inhibiting the growth of Cu-Sn reaction layer. Therefore, the growth of reaction layer and decrease of joint strength are inhibited by Zn addition after annealing.

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Convenient methods with simple devices comprised of an optical cell and prisms were proposed for the direct spectrophotometric measurement of adsorbed species at liquid-liquid interface, using a protonated meso-tetraphenylporphyrin in an aggregate form as an interfacial adsorbate. The spectrum of the aggregate within the visible wavelength region was effectively observed by three kinds of prism-cell assembly for (1) the double-phase transmission method, (2) the multiple attenuated total-internal reflection method and (3) the external reflection method. Characteristics of spectral appearance in each of the methods were described and discussed.

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It was well known that spectral reflectance information taken by using a CCD camera through X, Y and Z filters was much related to both brilliance and illumination. Also color information in the groups that composed of five similar colors under the different lighting condition was examined; the groups were achromatic color, red, green and blue. However, the similar color groups of cyan, magenta and yellow, which are complementary colors of red, green and blue, were not examined. Therefore, this paper examines the color features for the above three groups, and proposes a method due to fuzzy reasoning for estimating colors from seven similar color groups. First, we estimate a color group to which an objective color belongs in seven groups. Secondly, the objective color is extracted from five similar ones in the estimated group. The reliability of the proposed method is demonstrated on an experiment using the data on thirty-five colors.

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The stress intensity factors at the tips of a crack kinked at the interface of bonded anisotropic elastic media are analyzed. By using a singular point method, the problem is reduced to solving a system of singular integral equations with generalized Cauchy kernels. The characteristic equation that determines the stress singularity at the kink vertex is derived from the singular integral equations, and singular stress fields at the kink vertex are determined definitely. By taking into account of the stress singularity at the kink vertex, numerical results are given graphically for the stress intensity factors at the tips of the kinked crack.

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In order to elucidate the effect of synthesis conditions of Al-MCM-41 on the characteristics of the resultant samples, Al-MCM-41 samples were synthesized through non-hydrothermal reactions under diverse conditions. The following conditions were found to be favorable to prepare Al-MCM-41 with well ordered 2D-hexagonal structure from the reaction mixtures of lower Si/Al ratios: simultaneous addition of Si and Al sources into the solution containing both template of surfactant and anti-foaming agent, in neutral to acidic media (pH 3-7), at temperatures above Krafft point of the surfactant, and under vigorous stirring. These conditions may be associated with assembly of aluminosilicate sources with uniform composition (i.e., constant Si/Al ratio) around the template micelles, promoting hydrolysis and/or condensation of aluminosilicate and forming Al-MCM-41 with highly-ordered structures. Relatively weak acid sites are mainly consisted of Al-MCM-41 and similar distributions of acid strength are observed for the samples with different Si/Al species. Dealkylation reactions of 1, 3, 5-triisopropylbenzene, which are well known to proceed on Bronsted acid sites are catalyzed more effectively on Al-MCM-41 samples than on HY-zeolites. This means that at least, a part of Al was incorporated into the silica framework of MCM-41 structure as tetrahedrally coordinated species in Al-MCM-41 samples prepared in the present study.

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