• Polymer(Korea)
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• v.36 no.6
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• pp.789-794
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• 2012

Poly(lactic-co-glycolic acid) (PLGA) has been most widely used due to its advantages such as good biodegradability, controllable rate of degradation and metabolizable degradation products. We manufactured composite scaffolds of PLGA scaffold penetrated DBP gel (PLGA/DBP gel) by a simple method, solvent casting/salt leaching prep of PLGA scaffolds and subsequent soaking in DBP gel. Chondrocytes were seeded on the PLGA/DBP gel. The mechanical strength of scaffold, histology (H&E, Safranin-O, Alcian-blue) and immunohistochemistry (collagen type I, collagen type II) were performed to elucidate in vitro and in vivo cartilage-specific extracellular matrices. It was better to keep the characteristic of chondrocytes in the PLGA/DBP gel scaffolds than that PLGA scaffolds. This study suggests that PLGA/DBP gel scaffold may serve as a potential cell delivery vehicle and a structural basis for in vivo tissue engineered cartilage.

• Microbiology and Biotechnology Letters
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• v.10 no.3
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• pp.205-209
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• 1982

The enzyme-linked immunosorbent assay using the so-called "double-sandwich"technique was applied to determine Clostridium botulinum type F toxin. Polystyrene tubes were coated with horse anti-type F toxin serum and then toxin sample was added. The tubes were subsequently treated with rabbit anti-type F toxin IgG and sheep anti-rabbit serum IgG-horseradish peroxidase conjugate. By this technique, about 10 mouse intraperitoneal 50% lethal doses (ip LD/50/) of type F toxin could be detected. Low back-ground reading was achieved with the use of phosphate-buffered saline containing 0.05% Tween 20 and 1% bovine serum albumin as diluents of rabbit IgG and conjugate. Addition of EDTA in the diluents of toxin increased ELISA extinction value significantly. No cross-reaction was observed with botulinum type A and B toxin, but type E toxin gave sleight cross-reaction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1784-1797
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• 1996

The disk/blade assembly of a turbine engine is made in the shape of a dovetail type or a fir-tree type. Since disk fillet regions or contact surfaces undergo high stress comcentration, fatigue cracks frequentrly occur in the disk/blade assembly. Therefore, it is necessary to analyze the stress distributions in the fir-tree type disk/balde assembly and predict the region of fatigue failure. The stress distributions of the disk/blade assembly were investigated by using the photoelastic method and the finite element method. Two dimensional photoelastic techniques were used to investigate the stress distributions of contact surfaces and fillet regions. TH stress distributions were obtained by the shear-difference method and were compared to the finite element results. It was found that maximum tensile stresses were higher in the fillet region thatn in the contact surfaces of the fir-tree models. The finite element results showed good agreement with the experimental results.

• Journal of the Korean Electrochemical Society
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• v.10 no.2
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• pp.116-125
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• 2007

This article is concerned with synthesis, characterisation and electrochemical application of the mixed conducting perovskite type oxide to electrode materials for solid oxide fuel cell. First, this review provides a comprehensive survey of the various synthetic methods such as solid state reaction, Pechini, glycine nitrate process and sol-gel methods for the preparation of perovskite type oxide powders. Subsequently, the electrical and microstructural properties of the mixed conducting oxides were discussed in detail. Finally, as electrochemical applications of the mixed conducting perovskite type oxides to electrode materials for solid oxide fuel cell, fundamentals of theoretical ac-impedance model for porous mixed conducting electrodes were introduced. Furthermore, the ac-impedance behaviour of porous and dense mixed conducting electrodes prepared by various synthetic methods was discussed.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.47-50
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• 2010

This work discusses a two-step electroless plating method for preparing a Pt thin film on p-type InGaAs substrate, which is defined as Pt I and Pt II. A thin Pt catalytic layer formed in Pt I bath on the substrate at $65^{\circ}C$. In the following Pt II bath, thick Pt films then easily grew on the sensitized layer on InGaAs previously formed in the Pt I bath. The growth of Pt film is strongly influenced by the plating temperature and pH value. To study the plating time effect, the plating of Pt II bath is 5 to 40 min at $80^{\circ}C$ after using Pt I bath at 50~$65^{\circ}C$ for 5min of pH 8~13. Pt film for ohmic contact to p-type InGaAs was successfully prepared by using the two-step Pt electroless plating.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.30-37
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• 2007

The injection and spray characteristics of top-feed type injector was investigated under liquid phase injection fueled with liquefied petroleum gas (LPG). Different pressures and temperatures of fuel injection system were tested to identify the injection characteristics after hot soaking. MIE-scattering technique was used for verification of successful liquid phase injection after hot soaking. In case of bottom-feed type injector, the injection was accomplished at every experimental condition. In case of top-feed type injector, when the pressure of LPG was over 1.2 MPa, the injection was not executed. However, under the pressure were 1.2 MPa, the liquid phase injection after hot soaking was accomplished. The engine with top-feed type fuel injection equipment was restarted successfully after hot soaking.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.795-798
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• 1989

This paper presents some results of teleoperation R&D activities for radioactive work. Heavy power manipulator feature is integrated with vision system implementation of advanced type and tool adaptation to hand gripper. Some assodiated te datth activities of interests to the teleoperation and future directions are also presented.

• Journal of Gastric Cancer
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• v.3 no.4
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• pp.221-225
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• 2003

Purpose: The prognosis for Borrmann type 4 gastric cancer is dismal although therapies for gastric cancer have been developed. We investigated the outcomes for Borrmann type 4 gastric cancers compared to those for other types of cancer. Materials and Methods: Between 1993 and 2000, 777 patients with advanced gastric cancer underwent surgical resection at the Department of Surgery, Korea University Hospital. The clinicopathologic features of 138 patients with Borrmann type 4 carcinomas of the stomach were retrospectively reviewed from the database of gastric cancer. The results were compared with those of 639 patients with other types of gastric carcinomas. Results: Patients with Borrmann type 4 carcinomas tended to be younger and to have larger tumors. The location, the depth of invasion, lymph node metastasis, and distant metastasis were significantly different between the two groups. Patients with Borrmann type 4 carcinomas had a more advanced stage than patients with other types of carcinomas. The analysis of the treatment factors revealed that total gastrectomies were more frequent in the group with Borrmann type 4 carcinomas and that the curative resection rate of patients with Borrmann type 4 gastric carcinomas was lower than that of patients with other types of gastric carcinomas (P<0.001). The 5-year survival rate for Borrmann type 4 gastric cancer was $19.4\%$ and that for other types was $52.9\%$ (P=0.001). In curative cases, the 5-year survival rates were $32.8 \%$ for patients with Borrmann type 4 gastric carcinomas and $63.4\%$ for other types of carcinomas (P=0.001). Conclusion: Borrmann type IV gastric cancer has more advanced features and a poorer prognosis than other types of gastric cancer. Improving the prognosis for patients with Borrmann type 4 gastric cancer requires early detection and a curative resection.

• Korean Journal of Materials Research
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• v.12 no.10
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• pp.784-790
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• 2002

For mass product of nanocrystalline ZnO ultrafine powders, self-sustaining combustion process(SCP) and ultrasonic spray combustion method(USCM) were applied at the same time. Ultrasonic spray gun was attached on top of the vertical type furnace. The droplet was sprayed into reaction zone of the furnace to form SCP which produces spherical shape with soft agglomerate crystalline ZnO particles. To characterize formed particles, fuel and oxidizing agent for SCP were used glycine and zinc nitrate or zinc hydroxide. Respectively, with changing combustion temperature and mixture ratio of oxidizing agent and fuel, the best ultrasonic spray conditions were obtained. To observe ultrasonic spray effect, two types of powder synthesis processes were compared. One was directly sprayed into furnace from the precursor solution (Type A), the other directly was heated on the hot plate without using spray gun (Type B). Powder obtained by type A was porous sponge shape with heavy agglomeration, but powder obtained using type B was finer primary particle size, spherical shape with weak agglomeration and bigger value of specific surface area. 9/ This can be due to much lower reaction temperature of type B at ignition time than type A. Synthesized nanocrystalline ZnO powders at the best ultrasonic spray conditions have primary particle size in range 20~30nm and specific surface area is about 20m$^2$/g.

• Transactions of the Korean hydrogen and new energy society
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• v.8 no.2
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• pp.79-90
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• 1997

Extensive work has been done on investigating the inner cell pressure characteristics of sealed type Ni-MH battery in which Zr-Ti-Mn-V-Ni alloy is used as anode. The inner cell pressure of this type Ni-MH battery much more increases with the charge/discharge cycling than that of the other type Ni-MH battery where commercialized $AB_5$ type alloy is used as anode. The increase of inner cell pressure in the sealed type Ni/MH battery using Zr-Ti-Mn-V-Ni alloy system is mainly due to the accumulation of oxygen gas during charge/discharge cycling. The accumulation of oxygen gas arises mainly due to the low rate of oxygen recombination on the MH electrode surface during charge/discharge cycling. The difference of oxygen recombination rate between $AB_5$ type electrode and Zr-Ti-Mn-V-Ni electrode is caused by the difference of electrode reaction surface area resulting from different particle size after their activation and the difference of surface catalytic activity for oxygen recombination reaction, respectively. After EIS analysis, it is identified that the surface catalytic activity affects much more dominantly on the oxygen recombination reaction than the reaction surface area does. In order to suppress the inner cell pressure of Ni-MH battery where Zr-Ti-Mn-V-Ni is used as anode, it is suggested that the surface catalytic activity for oxygen recombination should be improved.