• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.203-216
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• 1990

The purpose of this study was to evaluate the cervical margin fitness in the collarless metal ceramic crowns formed by different techniques. Specimens were divided as follows : the metal ceramic crowns with metal butt margin as group I, the collarless metal ceramic crowns formed with resin binder technique as group II, and the collarless metal ceramic crowns formed with shoulder powder mixed with phosphate-bonded investment liquids on a refractory die as group III. Each group was made of five specimens, and their marginal fitness on each epoxy die was evaluated under scanning electron microscope of x200 magnification at three measuring points : mesial, central, distal. The following results were obtained. 1. The metal ceramic crowns with metal butt margin exhibited significantly better marginal fitness than the collarless metal ceramic crowns. The marginal fitness in descending order was group I, III, II. 2. The collarless metal ceramic crown formed with resin binder technique had the worst marginal fitness & showed cervical color variation and dermacation between the corrected porcelain & the dentin porcelain. 3. The collarless metal ceramic crowns formed with shoulder powder mixed with phosphate-bonded investment liquids on a refractory die exhibited significantly better marginal fitness & sharper marginal configuration than the other collarless group.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.537-545
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• 2007

The heavy metal removal capacity of filamentous green alga Cladophora sp. cultured together with wet-mixed solidified soil (loess) was tested. A Cladophora sp. was cultured for 5d, with added Chu No. 10 medium, in stream water contaminated by high concentration of heavy metals from a closed mine effluent. Heavy metal ion concentrations of the medium and in algal tissue were measured every day during the experiment. Dissolved metals (Al, Cd, Cu, Fe, Mn, Zn) in medium were rapidly removed (over 90% elimination) within 1-2d when alga and loess were added. Dissolved heavy metals dropped by only 10% when algae were cultured without loess. The Cladophora sp. accumulated much more heavy metals when cultured with loess than when the alga was cultured alone. Cladophora sp. exhibited a maximum uptake capacity for Al ($17,000{\mu}g^{-1}$ algal dry weight). The metal bioremoval capacities of the algae were in the order Al, Fe, Cu, Mn, Zn and Cd. The heavy metal removal capacity of Cladophora sp. showed significant increases when wet-mixed solidified soil was added to culture media.

• Journal of Welding and Joining
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• v.15 no.2
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• pp.72-80
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• 1997

The spatter generation rate of GMA welding with $CO_2$ gas shielding was measured with the change of welding conditions such as wire feeding rate and welding voltage and then the results were analized with the accompanying changes in metal transfer mode and in bead geometry. The spatter generation rate (SGR) was relatively low not only wit the short circuit transfer but with the truely globular transfer mode. However, the SGR resulted with the mixed mode were consistantly high. The resultant wave pattern of mixed mode was due to the coexistance of short-circuit and globular transfer and characterized by the frequent appearance of instantaneous short circuit. Considering the result of SGR and that of bead geometry, it could be concluded that when the wire feeding rate (or welding current) was either low or high, the optimum bead shape could be obtained along with the low spatter generation. However, in the middle range of wire feeding rate, the optimum bead shape was only obtained in the mixed mode condition resulting in the high spatter generation.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.311-324
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• 2018

Herein,the Neodymium ion ($Nd^{3+}$) doped CoAl-LDH have been successfully prepared via co-precipitation method and was used as a precursor of Nd-doped CoAl-mixed metal oxides (MMO). The photocatalytic activity of doped LDH and MMO was investigated in the degradation of an azo dye, C.I. Acid Red 14, under visible light irradiation. DRS and PL analysis demonstrated decreasing in the band gap energy and recombination of photo-induced charge carriers of Nd-doped LDH and MMO compared with the pristine CoAL-LDH. Due to significant difference in photocatalytic performance. A power law empirical kinetic model was obtained for predicting the photocatalytic degradation efficiency.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.86-93
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• 1999

Ceramic/metal bonded joints have led to increasing use of structural materials such as automobiles and heat engines. A method of strength evaluation focussing on fracture criterion of mixed mode was investigated in {{{{ {Si }_{3 } {N }_{4 } }}}}/metal bonded joint, Also Fracture toughness tests of {{{{ {Si }_{3 } {N }_{4 } }}}}/metal bonded joints with an interface crack were carried out and the stress intensity factors of these joints were analyzed by boundary element method. Form the results the fracture criterion and method of strength evaluation by the fracture toughness were proposed in {{{{ {Si }_{3 } {N }_{4 } }}}}/Metal bonded joints

• The Journal of Korea Robotics Society
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• v.4 no.4
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• pp.320-326
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• 2009

This paper proposed a new magnetic field detection algorithm to detect metal pieces in food producing processes. This algorithm can detect mixed metal pieces by sensing magnetic field. Some metal pieces are passed through an over-current circuit to magnetize them. The magnetic field sensor can detect the change in the magnetic field on theconveyor belt caused by the flow of the metal pieces in the food product. However, such a method detects the output of signals that change their amplitude and phase according to the movement of the conveyor belt with the food product, in which the equilibrium of the positive signal that is created in the receiver coil loses its balance due to the magnetized material. This includes not only the signal elements resulting from the effect of the alternating magnetic fields of the mixed metals, but also the signal elements resulting from the effect of the alternating magnetic fields of the examined object itself.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.233-238
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• 1998

Recently, the uses of ceramic/metal bonded joints for structural materials have increased in various engineering fields such as automobiles, heat engines, and so on. A method of strength evaluation focussing on fracture criterion of mixed was investigated in Si3N4/metal bonded joint. Also, Fracture toughness tests of Si3N4/metal bonded joints with an interface crack were carried out and the stress intensity factors of these joints were analyzed by boundary element method. From the results, the fracture criterion and method of strength evaluation by the fracture toughness were proposed in Si3N4/metal bonded joints

• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1298-1307
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• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

• Membrane and Water Treatment
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• v.15 no.3
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• pp.139-152
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• 2024

Mixed matrix membranes have gained significant recognition in the wastewater treatment industry for their effectiveness in removing dyes, proteins, and heavy metals from water sources. Researchers have developed an innovative technique to enhance properties of these membranes by incorporating amine-functionalized carbon nanotubes into the polymer matrix. This approach introduces amine functional groups onto the membrane surface, which are then modified with trimesoyl chloride and cyanuric chloride. The modified membranes are characterized by XPS to confirm successful bonding of amines with the trimesoyl chloride and cyanuric chloride. The surface charge of the modified membrane also plays a role in the modification process; the membrane modified with trimesoyl chloride has a negative surface charge, while the one modified with cyanuric chloride has a more positive charge. At the same acidic pH, the positive or negative charge of the mixed matrix membranes assists in enhancing the rejection of heavy metals. This results in improved antifouling properties for both modified membranes. The heavy metal rejection for all modified membranes is higher than for unmodified membranes, due to both adsorption and complexation abilities of the functional groups on the membrane surface with heavy metal ions. As the membrane surface functionalities increase through modification, the separation due to complexation also increases. The bulk morphology of the membrane remains unchanged, while roughness slightly increases due to the surface treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.456-461
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• 2012

The glycerol carbonate was synthesized by glycerol and urea using metal oxide catalysts. The physical properties of the prepared metal oxide catalysts were investigated by X-ray diffraction (XRD), specific surface area analysis (BET), field emission scanning electron microscopy (FE-SEM) and temperature programmed desorption (TPD). In addition, we confirmed the conversion of the glycerol and the yield of the glycerol carbonate according to characteristics of metal oxide catalysts. From XRD and FE-SEM analysis, the crystallite size and crystallinity of metal oxide catalysts decrease with addition of Al. In addition, the Zn-Al mixed metal oxide had higher catalytic activity than the pure ZnO due to decreased side reaction in the synthesis of glycerol carbonate.