• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.773-776
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• 2008

Restraining cracks on concrete structures can be the basic condition to improve the durability, so in this research, the resistibility on the drying shrinkage of concrete structures in the long period was being confirmed and as the reason of this shrinkage, the density of minute textures was being analyzed using a wooden prototype of a full scale produced with ready-mixed concrete and agents of glycol which can be used as a surfactant. As result of those tests, PFB technology can reduce the drying shrinkage by approximately $-100{\sim}200{\times}10^{-6}$ on a wooden prototype of a full scale and can also reduce the pore volume as the obstruction to the movement of gas or liquid by approximately $2.4{\sim}3.5$% so that PFB technology can be used to assure the resistibility on the drying shrinkage.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.674-679
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• 1998

Small water leak experiment was carried out in liquid sodium atmosphere using a specimen of ferrite steel, which will be expected to be a material of the heat transfer tube of liquid metal fast breeder reactor. Self-plugging phenomena of leak path could be explained by the products of reaction and corrosion by sodium-water reaction. Also, re-opening mechanism of self-plugged path could be explained by the thermal transient and vibration of heat transfer tube. As a result, perfect re-opening time of self-plugged leak path was observed to be 129 minutes after water leak initiation. Re-opening shape of a specimen was appeared with double layer of circular type, and re-opening size of this specimen surface was about 2 mm diameter on sodium side.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.800-806
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• 2008

The strain HK-12 was enriched and isolated from naturally fermented soybean for the production of fibrinolytic enzyme and the proteome of this enzyme induced during the incubation period was analyzed. The activity of fibrinolytic enzyme derived from supernatants of the HK-12 culture was performed by fibrin plate method for solid fibrinolytic activity. As the result, the fibrinolytic activity of HK-12 grown on the nutrient agar media was about 2.3 times greater than that of plasmin used as standard. The purified enzyme was prepared by a series of purification process including ammonium sulfate precipitation, DEAE-cellulose, Sephadex chromatography. The molecular weight of the enzyme was determined to approximately 23kDa with SDS-PAGE. In order to examine which strain HK-12 proteins increased or decreased during the incubation period, 2-DE analysis was performed. Protein spot #1 significantly expressed on the 2-DE gel of bacteria cultivated for 36-hrs was analysed. As the result of protein sequence analysis using MALDI-TOF MS, one protein was identified as serine protein kinase (PrkA).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.58-62
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• 2012

In this study, the hybrid rocket was developed that has a thrust of 1000 kgf level. The static fire test was shown that the thrust was 700 kgf level and trajectory was predicted by the maximum altitude of 12.5 km. The L/D ratio of KHyRoc-I has 28, but the KHyRoc-II were designed the small L/D ratio(18.3) using the seamless aluminium tube(Diameter : 250 mm). And KHyRoc-II has a thrust of 900 kgf level, that is designed with internal ballistics and trajectory was predicted by the maximum altitude of 7.4 km.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.28-41
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• 2019

We carried out performance analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor. We analyzed transient-dynamic behavior of fluids inside the steam generator to vent into a sodium dump tank or a water dump tank when tubes in the steam generator were broken to cause a large-water-leak accident. Accordingly, we preliminarily evaluated design requirements of our system. Our results showed that sodium in the shell side of the steam generator and in Intermediate Heat Transport System was completely vented within 50 s and feed water in the tube side of the steam generator was completely vented within 2.5 s. It was analyzed that pressure of the tube side of the steam generator was higher than pressure of the shell side of the steam generator, which showed that sodium in the shell side did not flow into the tube side. Our results are expected to be used as basis information to performance analysis of Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.51-58
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• 2023

Hypergolic propellants, which can ignite themselves without an ignition source, are difficult to handle due to their corrosiveness and toxicity. Therefore, it is necessary to develop green hypergolic propellants with little or no toxicity. In this study, basic research on green hypergolic ignition propellants was conducted. With 95% hydrogen peroxide as an oxidizer and CNU_HGFv1 as a fuel, ignition and combustion characteristics of propellants were evaluated through a drop test, an ignition test, and a combustion test. As a result of the drop test, the ignition delay time was 9.7 ms. It was 27 ms in the ignition test, which was fast enough to be used as a propellant. As a result of the combustion test, a combustion efficiency of 95.4~98.1% was achieved at about 11.7 bar. It was confirmed that fast and stable combustion was possible without hard start or combustion instability.

• KSBB Journal
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• v.22 no.1
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• pp.16-21
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• 2007

Although Energy demands of modern society increase rapidly, current energy would be exhausted shortly. Therefore development of bio-ethanol production process from cellulose containing materials was extremly demanded. Therefore development of highly functional cellulase is requisite for this purpose. In this study cellobio-hydrolase (CBH1) gene from Trichorderma reesei was used to increase cellulase activity by directed evolution and highly functional cellobio-hydrolase was obtained and characterized.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.1
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• pp.1-12
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• 1998

To examine the possibility of protein recycling of shaving scraps containing chromium generated from manufacturing process of leather, the optimum hydrolysis conditions and the withdrawal methods of low molecular weight protein for using the liquid fertilizer sources by investigation of solubilities of hydrolyzed protein, inorganic nutrients contents and molecular weight distributions of hydrolyzed protein from shaving scraps treated with mixed alkaline inducing agents and mixed alkaline proteolytic enzymes including MgO were investigated. In hydrolysis of shaving scraps treated with mixed alkaline inducing agents, the solubility of shaving scraps were clearly different with 65~85% according to the sorts of the inducing agents, and the degree of hydrolysis was high in the order of NaOH, $Ca(OH)_2$ and KOH. The average molecular weights of withdrawal hydrolyzed protein were 10, 40 and 80 KD treated with NaOH, $Ca(OH)_2$ and KOH, respectively. And the chromium contents was about 15 ppm. In hydrolysis of shaving scraps treated with mixed alkaline proteolytic enzymes, the bility of shaving scraps were high in the order of alcalase, esperase and savinase. In c of treating 0.5% alcalase, the low molecular weight of hydrolyzed protein could be withdrawn. The solubility of the hydrolyzed protein was about 85%, the average molecular weight of the protein was below 1 KD and chrome content of the protein was below 10 ppm.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.45-50
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• 2008

Purpose: A soft contact lens was manufactured by adding naringin known as natural anti-bacterial material to resin solution. With solution eluted from manufactured contact lens, we examined its optical properties, physical and chemical states of naringin in the polymer, and elution properties. Methods: The soft contact lens with naringin was synthesized by bulk polymerization method. IR spectrum and HPLC were used to define the bonding type of naringin itself in the soft contact lens contained naringin, elution process of naringin to the saline solution, and the amount of naringin solution eluted from the lens with elapsed time. Results: Naringin was continuously eluted with constant concentration from the soft contact lens for about a month and the structure ofnaringin which is eluted was as same as before it was added to resin solution. Any change in optical properties such as transmittance couldn't be found. Bonding state and the structure of naringin in contact lens were explained with IR spectrum and HPLC results. Conclusions: In the contact lens with naringin, naringin remained in the contact lens bonding with weak hydrogen bonding and/or van der Waals force between naringin and polymer. Naringin was continuously eluted from the contact lens contained naringin during about 1 month. Even after 1 month, it showed that the concentration of the naringin eluted was approximately 10 ppm in a day. From the results, adding naringin to the soft contact lens resin is very effective method for manufacturing the soft contact lens which has anti-bacterial function for a period of time.

• Journal of Plant Biotechnology
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• v.29 no.3
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• pp.193-198
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• 2002

The objective of this study was to determine the effects of phenylacetic acid (PAA) on embryo production in anther and microspore culture of herbaceous peony (Paeonia lactiflora Pall.). The anthers of herbaceous peony were cultured on MS medium with 0 to 100 mg/L PAA according to two-step culture method. The ruptured anthers were transferred onto embryo formation medium without growth regulators. The MS medium with 2 mg/L PAA was effective in enhancing of direct embryogenesis and producing of normal embryo with two cotyledons from the cultured anthers. However, the increase of PAA concentration more than 5 mg/L PAA inhibited the embryo formation and promoted to callus formation from the anthers. The PAA affects significantly on the division of microspore and embryo formation in shed pollen culture and the best result was obtained from a medium supplement with 2 mg/L PAA. The preculture of anther for 10 days on solid medium with 2 mg/L PAA was effective for embryo formation from shed microspore of herbaceous peony.