• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.328-334
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• 2007

Chemical heat pump system of 2-propanol/acetone/hydrogen is most suitable to the recovery of waste heat of power plant. various types of 5 wt% Pt-alumina catalysts were prepared for 2-propanol dehydrogenation using sol-gel method. The characteristics and the dehydrogenation reaction rate of each catalyst were investigated. Pt-alumina xerogel catalyst has excellent reaction rate and good durability in comparison with the existing alumina supported Pt catalysts. Pt-alumina aerogel catalyst had the highest reaction rate in all prepared catalysts, but sufficient aging time was necessary to maintain its reaction rate. A potential advantage of the aerogel catalyst is the fact that the high temperature heat treatment is not required. Without heat treatment or with low temperature heat treatment, the Pt-alumina aerogel catalyst has excellent reaction rate as well as durability and this gives us the economic advantage. Alumina xerogel supported Pt catalyst prepared by incipient wetness method showed good reaction rate, and had good mechanical strength. Blank alumina xerogel prepared by sol-gel method can be used for the support of metal catalysts.

• Clean Technology
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• v.6 no.2
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• pp.121-127
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• 2000

There are several kinds of hazardous materials in incinerator flue gas, such as particulate matter, acid gas, heavy metal, dioxin, etc. The activated carbon adsorption is considered as one of the methods removing dioxin from flue gas. Without any additional equipment and facilities, the activated carbon was mixed with lime and sprayed in the semi-drying reactor of an incinerator and filtered in the bag filter, and its efficiency of removing hazardous organic material was investigated. 1,2-dichlorobenzene (o-DCB) was used as a precursor material of dioxin and the effects of the activated carbon amount, the operating temperature of the reactor, and the atomizer r.p.m were measured and analyzed. Experimental results showed that the optimum outlet temperature of the reactor was $145^{\circ}C$ considering the performance of the bag filter, and the adsorption performance improved with the increase of the atomizer r.p.m. Also the performance of removing o-DCB in the bag filter is higher than of the semi-drying reactor.

• Composites Research
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• v.29 no.1
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• pp.40-44
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• 2016

Nuclear fuel cladding used in a nuclear power plant must possess superior oxidation resistance in the coolant atmosphere of high temperature/high pressure. However, as was the case for the critical LOCA (loss-of-coolant accident) accident that took place in the Fukushima disaster, there is a risk of hydrogen explosion when the nuclear fuel cladding and steam reacts dramatically to cause a rapid high-temperature oxidation accompanied by generation of a huge amount of hydrogen. Hence, an active search is ongoing for an alternative material to be used for manufacturing of nuclear fuel cladding. Studies are currently aimed at improving the safety of this cladding. In particular, ceramic-based nuclear fuel cladding, such as SiC, is receiving much attention due to the excellent radiation resistance, high strength, chemical durability against oxidation and corrosion, and excellent thermal conduction of ceramics. In the present study, cladding with $SiC_f/SiC$ protective films was fabricated using a process that forms a matrix phase by polymer impregnation of polycarbosilane (PCS) after filament-winding the SiC fiber onto an existing Zry-4 cladding tube. It is analyzed the oxidation and microstructure of the metal cladding with $SiC_f/SiC$ composite protective films using a drop tube furnace for thermal shock test.

• Journal of IKEEE
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• v.21 no.4
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• pp.368-374
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• 2017

In this Paper, we developed a low power type LED security light using LED lighting that substitutes a 220[V] commercial power source for a solar cell module instead of a halogen or a sodium lamp. in addition, a PWM type drive control circuit is designed to minimize the heat generation problem and the drive current of the LED drive controller. in developed system, The light efficiency measurement value is 93.6[lm/W], and a high precision temperature sensor is used inside the controller to control the heat generation of the LED lamp. In order to eliminate the high heat generated from the LED lamp, it is designed to disperse quickly into the atmosphere through the metal insertion type heat sink. The heat control range of LED lighting was $50-55[^{\circ}C]$. The luminous flux and the lighting speed of the LED security lamp were 0.5[s], and the beam diffusion angle of the LED lamp was about $110[^{\circ}C]$ by the light distribution curve based on the height of 6[m].

• Journal of Life Science
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• v.24 no.6
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• pp.603-611
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• 2014

The lectins were separated from Korean and Chinese mung bean seeds finally via chromatography using Sephadex G-100 and their biochemical features were studied and compared. They showed no hemagglutination with human red blood cells regardless of trypsin treatment and showed hemagglutination with only trypsin treated rabbit red blood cells. The molecular weights of two lectins were identified as 54 kDa and 28 kDa by SDS-PAGE. It was found that while the optimal reaction temperature of the lectin from Korean mung bean was $60^{\circ}C$, that of the lectin from Chinese mung bean seeds was $50^{\circ}C$. It was found also that the most thermal stable temperature of the seed lectin from Korean mung bean seeds was $50^{\circ}C$ and the lectin from Chinese mung bean was $40-50^{\circ}C$. The lectin from Korean mung bean seeds showed the highest activity at pH 3.2 and the lectin from Chinese mung bean showed the highest activity at pH 6.2. It was identified that when treating a denaturant, thiourea and guanidine-HCl resulted in no hemagglutination, so they induced denaturalization. It was identified also that there was no hemagglutination with urea, so it did not induced denaturalization. They showed no septicity to 6 types of carbohydrates including D-glucose. In addition, the lectins from the two mung bean seed had specificity to metal ions.

• Journal of Life Science
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• v.23 no.12
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• pp.1486-1494
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• 2013

A high protease-producing strain was isolated and identified from the digestive tract of octopus vulgaris by detecting a hydrolysis circle of protease and its activity. The strain was identified by morphology observation, biochemical experiments, and 16S rRNA sequence analysis. The protease obtained from the strain was purified by a three-step process involving ammonium sulfate precipitation, carboxy methyl-cellulose (CM-52) cation-exchange chromatography, and DEAE-Sephadex A50 anion-exchange chromatography. The properties of protease were characterized as well. The strain Bacillus sp. QDV-3, which produced the highest activity of protease, was isolated. On the basis of the phenotypic and biochemical characterization and 16S rRNA gene-sequencing studies, the isolate was identified as follows: domain: Bacteria; phylum: Firmicutes; class: Bacilli; order: Bacillales; family: Bacillaceae; and genus: Bacillus. The isolate was shown to have a 99.2% similarity with Bacillus flexus. A high active protease designated as QDV-E, with a molecular weight of 61.6 kDa, was obtained. The enzyme was found to be active in the pH range of 9.0-9.5 and its optimum temperature was $40^{\circ}C$. The protease activity retained more than 96% at the temperature of $50^{\circ}C$ for 60 min. Phenylmethylsulfonyl fluoride (PMSF) inhibited the enzyme activity, thus confirming that this protease isolated from Bacillus sp. QDV-3 is an alkaline serine protease. Metal ions, $Mn^{2+}$ and $Mg^{2+}$, were determined to enhance the protease activity, whereas $Ba^{2+}$, $Zn^{2+}$, and $Cu^{2+}$ were found to inactivate the enzyme.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.706-711
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• 2002

High-pure tantalum powder was fabricated through Na reduction process and has been produced by using $K_2$TaF$_{7}$, and KCI, KF for raw material and diluent, respectively. A raw material and diluent were charged at the hestalloy bomb by the weight rate of 1:2, 1:1, 1:0.5 and 1:0.25 each other, investigated properties of morphology, chemical composition and yield and particle size after reduced. Ta metal has been achieved by reduction of $K_2$$TaF_{7}$ 500g with 1% sodium in excess of stoichiometric amount in the charge at a reduction temperature of $850^{\circ}C$ for 3hours. According to amount of the diluent, a formation of the powder doesn't have an effect. The diluent prevented the temperature rising caused from the heat of reaction and it maintained the speed of reducing reaction. But in the mixture ratio of raw material and diluent in the 1 : 2 and 1 : 0.25, an oxide and partially not reacted K were detected. As the amount of diluent increased, the size of tantalum powder decreased. According as raw material and the mixture ratio of diluent change from 1:0.25 to 1:2, the size is decreased from 5$\mu\textrm{m}$ to 1$\mu\textrm{m}$, and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. In the case of average size of Tantalum powder which is the mixture ratio (1:0.5), we would get the Ta powder with grain size about 3$\mu\textrm{m}$, which come close to the average size (2~4$\mu\textrm{m}$) of tantalum powder which is used commonly in the present is Ta powder about 3$\mu\textrm{m}$.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.389-394
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• 2003

In order to screen microorganisms producing phopholipase D (PLD) had high transphosphatidylation activity, about 1,000 Actinomycetes strains were isolated from the 63 soil samples, collected over 6 local area in Korea. When the hydrolytic activity in the supernatant was determined, 131 strains produced PLD more than 0.3 U/ml. Among 131 culture broths tested, 23 ones had transphosphatidylation activity higher than 20% and finally one strain (Actinomycetes KF 923), which had highest hydrolytic and transphophadylation activity, was selected. Actinomycetes KF923 showed the highest hydrolytic activity (13 U/ml) and phosphatidylation activity (95%) after 48 h fermentation using the P medium (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, $CaCo_3$ 0.4%, pH 7.2). PLD was purified from the culture broth of Actinomycetes KF923 and the specific activity of purified PLD was 567 U/mg. The molecular weight of PLD was about 55 kD and the optimum pH and temperature were 6.0 and $60^{\circ}C$, respectively. The stability of PLD toward pH and temperature were high around pH 8.0 and below $40^{\circ}C$. Special metal ions were not necessary to the PLD activity.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.33-38
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• 2009

The use of portable devices has created the need for new reliability criterion of drop impact tests because of the tendency to accidentally drop in the use of these devices. The effects of different PCB surface finishes (organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG)) and high temperature storage (HTS) test on the drop reliability were studied. Various drop test conditions were used to evaluate a drop reliability of assemblies to endure such impact and shock load. In the case of the as-reflowed samples (no HTS test), the SAC/OSP boards exhibited a better drop impact reliability than that of SAC/ENIG. However, the reverse was true if HTS test is performed. In addition, significant decrease of drop reliability was observed for both SAC/ENIG and SAC/OSP assemblies after HTS test. It was also observed that the thickness of intermetallic compound layer do play an important role in the brittle fracture of drop test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.21-27
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• 2016

Global warming due to greenhouse gas emissions is considered as a major problem worldwide, and many countries are making great efforts to reduce carbon dioxide emissions. Many technologies in post-combustion, pre-combustion and oxy-fuel combustion $CO_2$ capture have been developed. Among them, a hybrid pre-combustion $CO_2$ capture system of a water gas shift (WGS) reactor and a membrane gas separation unit was investigated. The 2 stage WGS reactor integrated high temperature shift (HTS) with a low temperature shift (LTS) was used to obtain a higher CO conversion rate. A Pd/Cu dense metal membrane was used to separate $H_2$ from $CO_2$ selectively. The performance of the hybrid system in terms of CO conversion and $H_2$ separation was evaluated using a 65% CO, 30 % $H_2$ and 5% $CO_2$ gas mixture for applications to pre-combustion $CO_2$ capture. The experiments were carried out over the range of WGS temperatures ($200-400^{\circ}C$), WGS pressures (0-20bar), Steam/Carbon (S/C) ratios (2.5-5) in a feed gas flow rate of 1 L/min. A very high CO conversion rate of 99.5% was achieved with the HTS-LTS 2 stage water gas shift reactor, and 83% $CO_2$ was concentrated in the retentate using the Pd/Cu membrane.