• Bulletin of the Korean Chemical Society
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• v.6 no.4
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• pp.210-214
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• 1985

Urokinase, a plasminogen activator, was conjugated with dextran by the cyanogen bromide activation-coupling method. The resulting water-soluble conjugate was purified by gel permeation chromatography on Sephadex G-200. The maximal activity was obtained when the ratio of urokinase/dextran was 1/20 for the coupling. The final preparation showed 5 CTA units/mg conjugate, 300 CTA units/mg protein, 8.4 % activity retention, and 47 % protein retention. The urokinase-dextran conjugate had good thermal, pH and storage stabilities. In addition, it showed greater resistance to the inhibitory effect of human plasma than native urokinase. Also in vitro biological half-life of urokinase increased 40 times by this conjugation. In view of activity, excellent stability and increased half-life, the conjugate can be a potential fibrinolytic agent in an injectable form.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2296-2302
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• 2018

Internally plasticized PVC was prepared via chemical reaction of azide PVC and alkynyl group containing castor oil methyl ester. The chemical structure of alkynyl group containing castor oil methyl ester and internally plasticized PVC was characterized with FT-IR and $^1H$ NMR. Properties of internally plasticized PVC, including thermal stability, tensile tests and resistance to extraction in different solvents, was investigated. The results showed that alkynyl group containing castor oil methyl ester, as internal plasticizer of PVC, not only decreased the $T_g$ of PVC from $84.6^{\circ}C$ to $41.6^{\circ}C$ efficiently, but also presented no plasticizer loss in five different solvents. The tensile tests showed that elongation at break and tensile strength of internally plasticized PVC was 353.8% and 18.1 MPa. The internally plasticized PVC has potential application in replacing the traditional PVC material in PVC products with high durability.

• Earthquakes and Structures
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• v.22 no.2
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• pp.137-145
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• 2022

As steel is highly sensitive to temperature variations, fire exposure is more destructive in the case of steel structures in comparison to the concrete ones. The performance of an intermediate three-story steel moment frame with 4 spans was studied under the service load, thermal load and post-earthquake fire in this paper. Also, the effects of passive fire-protection materials such as ordinary cement-based and fire-retardant coatings were investigated. To model and analyze the structure; Abaqus software is utilized. In order to apply the earthquake effect, the push-over analysis method is employed. Changes in the stories deflection, endurance time and growth of nonlinear regions due to losses in the steel stiffness and strength, are among the issues considered in this study. As an interesting finding, the beams protected by ordinary cement-based coating could sustain the fire exposure at least for 30 minutes in all cases. The mentioned time is increased by employing a new fire-retardant protection, which could prevent significant loss in the structure resistance against fire, even after 60 minutes of exposure to fire.

• Journal of Surface Science and Engineering
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• v.57 no.4
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• pp.254-264
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• 2024

This paper reviews the dielectric breakdown resistance and behavior of anodic oxide films in air environment. It begins with a description of the dielectric breakdown mechanisms of dielectric materials. The paper then introduces different types of dielectric materials and compares them in terms of dielectric strength, thermal conductivity, mechanical strength and cost. Next, the paper summarizes various fabrication methods for dielectric aluminum oxide layers, discussing the advantages and disadvantages of each method. Finally, it provides an overview of current studies on the dielectric breakdown properties of anodic aluminum oxide films formed on different aluminum alloys in various electrolytes.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.35-41
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• 2016

Ceramic-metal based high power LED array package was developed via thick film LTCC technology using a glass-ceramic insulation layer and a silver conductor patterns directly printed on the aluminum heat sink substrate. The thermal resistance measurement using thermal transient tester revealed that ceramic-metal base LED package exhibited a superior heat dissipation property to compare with the previously known packaging method such as FR-4 based MCPCB. A prototype LED package sub-module with 50 watts power rating was fabricated using a ceramic-metal base chip-on-a board technology with minimized camber deformation during heat treatment by using partially covered glass-ceramic insulation layer design onto the aluminum heat spread substrate. This modified circuit design resulted in a camber-free packaging substrate and an enhanced heat transfer property compared with conventional MCPCB package. In addition, the partially covered design provided a material cost reduction compared with the fully covered one.

• Journal of Sensor Science and Technology
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• v.18 no.2
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• pp.110-115
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• 2009

Polystyrene (PS) microspheres were used to good advantage as a template material to prepare macroporous $TiO_2$ thin films. This is enabled to run the thermal decomposition of the PS without the collapsing of the 3-D macroporous framework during the calcination step. $TiO_2$ thin films were deposited onto the colloidal templated substrates at room temperature by RF sputtering, and then samples were thermally treated at $450^{\circ}C$ for 40.min in air to remove the organic colloidal template and induce crystallization of the $TiO_2$ film. The macroporous $TiO_2$ thin film exhibited a quasi-ordered partially hexagonal close-packed structure. Burst holes, estimated to be formed during PS thermal decomposition, are seen as the hemisphere walls. the inner as well as the outer surfaces of the hollow hemispheres formed by the method of thermal decomposition can be easily accessed by the diffusing gas species. As a consequence, the active surface area interacting with the gas species is expected to be enlarged about by a factor of fourth as large as compared to that of a planar films. Also the thickness at neighboring hemisphere could be controlled a few nm thickness. If the acceptor density becomes as large that depletion width reaches those thickness, the device is in the pinch off-situation and a strong resistance change should be observed.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.1-5
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• 2019

In the field of combined cycle power generation, thermal barrier coating(TBC) protects the super-heat-resistant alloy, which forms the core component of the gas turbine, from high temperature exposure. As the turbine inlet temperature(TIT) increases, TBC is more important and durability performance is also important when considering maintenance cost and safety. Therefore, studies have been made on the fabrication method of TBC and super-heat-resistant alloy in order to improve the performance of the TBC. In recent years, due to excellent properties such as high temperature creep resistance and high temperature strength, turbine blade material have been replaced by a single crystal superalloy, however there is a lack of research on TBC applied to single crystal superalloy. In this study, to understand the isothermal degradation performance of the TBC applied to the single crystal superalloy, isothermal exposure test was conducted at various temperature to derive the delamination life. The growth curve of thermally grown oxide(TGO) layer was predicted to evaluate the isothermal degradation performance. Also, microstructural analysis was performed by scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDS) to determine the effect of mixed oxide formation on the delamination life.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.80-83
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• 2000

In this work we deposited Pentacene thin film by OMBD at the various substrate temperatures, deposition rate and the various annealing temperatures for the fabrication of organic TFT and investigated the electrical and film surface characteristics such as sheet resistance, contact resistance and conductance Film thickness were measured by $\alpha$-step and the sheet resistance, contact resistance and conductance were extracted from the relation between the distance of the contacts and the resistance. During the film deposition the substrate temperature was held at 3$0^{\circ}C$, 4$0^{\circ}C$, 5$0^{\circ}C$, 6$0^{\circ}C$, 8$0^{\circ}C$ and 10$0^{\circ}C$, respectively. After the film deposition, Au contact was deposited by thermal evaporation. For the effect of annealing, the thin film was annealed in the nitrogen environment at 10$0^{\circ}C$ and 14$0^{\circ}C$ for 10 seconds, respectively. Film surface characteristics at the vatious substrate temperatures were measured by AFM. The crystallization of thin film was improved as the substrate temperatures were increased and the maximum gram size was 4${\mu}{\textrm}{m}$. The conductivity of thin film was found to be 7.40 $\times$10$^{-7}$ ~ 7.78$\times$10$^{-6}$ S/cm and the minimum contact resistance was 2.5324 ㏁.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.670-677
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• 2010

There are many surface protection methods for numerous steel structures being used under severely corrosive environment, one of them, metallizing(thermal spray) is a available protection method which is comparatively and recently developed for surrface protection of various steel structures. However coating film obtained by spraying is to be needed increasingly more good corrosion resistance due to accelerating of environmental contamination. In this study, coating films(DFT:$200{\mu}m$) are performed with arc spray by wire metal and their types of films are pure zinc, pure aluminum, alloy film(Al:Zn=85:15) and alloy film(Al:Zn=95:5). And corrosion resistance of their films was investigated with electrochemical methods in seawater solution. Pure aluminum film showed a relatively somewhat good corrosion resistance compared to among those of other films and alloy films also showed a good corrosion resistance compared to pure zinc film. Especially it was observed that pure aluminum film showed a comparatively good corrosion resistance than that of alloy film named as galvarium spray(Al:Zn=85:15) in seawater solution. Morphology of corroded surface of pure zinc film appeared the pattern like intergranlar corrosion, however films of pure aluminum and alloy metal showed a general corrosion pattern.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.22-28
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• 2017

The performance of lithium ion batteries used in electric vehicles (EV) varies greatly depending on the battery temperature. In this paper, the finite difference method was used to evaluate the temperature change, state of charge (SOC), internal resistance, and voltage change of the battery due to heat generation in the battery. The simulation model was linked with AMESim to calculate the driving range of an EV traveling in New European Driving Cycle (NEDC) mode. As the temperature dropped below $25^{\circ}C$, the internal resistance of the battery increased, which increased the amount of heat generated and decreased the driving range of EV. At battery temperatures above $25^{\circ}C$, the driving range was also decreased due to reduced SOC that deteriorated the battery performance. The battery showed optimal performance and the driving range was maximized at $25^{\circ}C$. When battery temperatures of $-20^{\circ}C$ and $45^{\circ}C$, the driving range of EV decreased by 33% and 1.8%, respectively. Maintaining the optimum battery temperature requires heating the battery at low temperature and cooling it down at high temperature through efficient battery thermal management. Approximately 500 W of heat should be supplied to the battery when the ambient temperature is $-20^{\circ}C$, while 250 W of heat should be removed for the battery to be maintained at $25^{\circ}C$.