• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.471-476
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• 1998

Microbiological spoilage of marine fish is complex process occurring by bacteria, yeasts and molds. There have been rare study for saprophytic yeasts although having enormous numbers of bacteriological studies on the spoilage of marine fish. The 14 genera of yeasts isolated from mackerel (Scomber japonicus) with high frequency of occurrence were Candida sp., Rhodotorula sp., Torulopsis sp., Cryptotoccus sp. and Tricosporon sp. Among these ones Candida lipolytica was identified as the strongest proteolytic yeast, then named Candida lipolytica FM5 (C. lipolytica FM5). C. lipolytica FM5 showed optimum growth at $25^{\circ}C$, pH 7.0 and could grow at $5^{\circ}C$ and in medium containing $10\%$ sodium chloride, To evaluate the saprophytic activity of the selected strain, C, lipolytica FM5 and Pseudomonas fluorescens ATCC 17571 which is one of representative spoilage bacteria were individually inoculated into the sterilized fish muscle homogenates, and then pH changes and volatile basic nitrogen (VBN) values were checked during the storage at various temperatures. According to the experimental results, the productions of VBN by C. lipolytica FM5 in the fish muscle homogenates were 50 mg-N/100 g at $5^{\circ}C$, 152 mg-N/100 g at $15^{\circ}C$ and 379 mg-N/100 g at $25^{\circ}C$ for 1 week storage, respectively. Above results were nearly same as in case of Ps. fluorescens ATCC 17571 inoculation. It suggest that sapyophytic yeasts also have important role in spoilage of marine fish.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.97-107
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• 2020

In this study, finite element analysis was carried out through the finite element analysis program (ANSYS) to investigate the fire resistance of composite columns in fire. Transient heat transfer analysis and static structural analysis were performed according to ASTM E 119 heating curve and axial force ratio 0.7, 0.6, 0.5 by applying stress-strain curves according to temperature, and loading heating experiments were carried out under the same conditions. In addition, the nominal compressive strength of the composite column according to the heating time according to the standard(Eurocode 4) was calculated and expressed as the axial force ratio and compared with the analytical and experimental values. Through the analysis, As a result of finite element analysis, the fire resistance time was 180 minutes and similar value to the experimental value was obtained, whereas the fire resistance time 150 minutes and 60 minutes were derived from the axial force ratios 0.6 and 0.7. In addition, it was confirmed that the fire resistance time according to the axial force ratio calculated according to the reference equation (Eurocode 4) was lower than the actual experimental value. However, it was confirmed that the standard(Eurocode 4) was higher than the experimental value at the axial force ratio of 0.7. Accordingly, it is possible to confirm the fire resistance characteristics(time-axial force ratio relationship) of the SRC column at high axial force, and to use the experimental and anaylsis data of the SRC column as the data for verification based on Eurocode.

• Journal of Radiation Protection and Research
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• v.23 no.2
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• pp.83-88
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• 1998

Chitosan is a nontoxic natural chealtor which was made by chitin, and reduced a contamination of radiostrontium in animals. In this experiment, A different molecular weight of C-14 chitosan was intravenously administered to mice, and then the distribution of C-14 chitosan in the body was observed. Male mice (8 to 10 weeks, body weight of 30 to 35g) of ICR strain were used. C-14 chitosan was diluted with saline and then given intravenously in mice. After the administration of C-14 chitosan, mice was sacrificed at the 6th hour, 1st, 3rd, 5th, and 7th day. Beta radioactivities in the blood, liver, kidney, liver, muscle, testis, and urine was measured using a liquid scintillation analyzer. Most of the C-14 chitosan was excreted through urine within 6 hours. Biodistribution of C-14 chitosan was similar despite the difference of moleclar weight. Higher distributions of radioactivities were found in the liver, kidney, spleen. The relative concentration in tissue increased for the 6 hours and then decreased. In conclusion, most of C-14 chitosan was excreted through urine despite the difference of molecular weight. and, low molecular weight of C-14 chitosan showed higher distribution than high molecular weight of C-14 chitosan in tissues.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.228-233
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• 2018

We isolated microorganisms from soil, which is sampled at forest, Kyeonbuk, Korea, as cellulolytic microorganisms. The isolated strains were identified by analysis of 16S rRNA gene from the starins. The result, four kinds of Bacillus subtilis, one kind of Bacillus amyloliquefaciens, and one kind of Bacillus cereus were identified. Among these strains, Bacillus subtilis was selected due to its high cellulase activity and this strain was named as Bacillus subtilis CNS. The optimum pH and temperature of the cellulase from Bacillus subtilis CNS was pH 5.0 and $40^{\circ}C$, respectively. In the investigation of pH and temperature stability, the cellulase from Bacillus subtilis NSC stabled pH 4.0~6.0 range and until $40^{\circ}C$ for 30 min perfectly. In the enzyme activity for various cellulosic substrate, cellulase from Bacillus subtilis CNS showed the highest activity for CM-cellulose. And, the enzyme activities for alkali swollen cellulose, Alpha-cellulose, Sigmacell-cellulose, and Avicel were approximately 31%, 8%, 8% and 4% of activity for CM-cellulose, respectively. In the degradation of CM-cellulose, the 0.26 U/ml and 0.52 U/ml of cellulase showed 0.43 and 0.76 U/ml activity for CM-cellulose after the reaction of 120 min, respectively.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.367-379
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• 2019

Pyeongan Supergroup (PS) in the Taebaeksan basin preserves key geological evidences to understand the tectonometamorphic evolution of the Songrim orogeny that affected the formation of the Korean Peninsula during the late Paleozoic to early Mesozoic. The aims of this paper therefore are to investigate the characteristics of the Songrim orogeny based on the previous results of metamorphism and deformations of the PS, and then to review geological significance and research necessity of the PS. Age distributions and Th/U ratio of detrital zircon in the PS indicate that sedimentary environment of the Taebaeksan basin during the late Paleozoic was arc-related foreland basin and retro-arc foreland basin at the active continental margin. In addition, the main magmatic activities occurred in the early Pennsylvanian and Middle Permian, thus sedimentation and magmatic activities occurred simultaneously. The PS was affected by lower temperature-medium pressure (M1) and medium temperature and pressure (M2) regional metamorphism during the Songrim orogeny. During M1, slate and phyllite containing chloritoid, andalusite, kyanite porphyroblasts intensively deformed by E-W bulk crustal shortening combined with folding and shearing. And garnet and staurolite porphyroblasts were formed during the N-S bulk crustal shortening accompained by M2. Such regional metamorphism of the PS is interpreted to occur in an area where high strain zone is localized during ca. 220-270 Ma. In order to elucidate the evolution of the Taebaeksan basin and tectonic features of the Songrim orogeny, it is expected that the study will be carried out such as the regional distribution of metamorphic zones developed in the PS, characteristics and timing of deformations, and late Paleozoic paleo-geography of the Taebaeksan basin.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.405-411
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• 2007

This study was carried out to measure insoluble phosphorus fractions content fixed in different soil type and isolate a superior phosphate solublizing bacteria(PSB) producing free phosphate in citrus orchard soil. Distribution of insoluble phosphate fraction ordered Al-P>Ca-P>Fe-P in the investigated citrus orchards. Insoluble phosphate fraction such as Al-P, Ca-P, Fe-P were higher in volcanic ash than in non-volcanic ash soil. A PSB with high holo zone in PDA-P medium isolated from citrus orchard soil. This strain identificated by MIDI system as Bacillus sphaericus. The optimum growth of pH and temperature were at 4~5, $30^{\circ}C$, respectively. When Bacillus sphaericus cultured at $25^{\circ}C$, 150 rpm condition in LB broth medium included different phosphate. Bacillus sphaericus produced free phosphate in the culture broth medium from tricalcium-phosphate(207.0 ppm), aluminium phosphate(324.5 ppm) and hydroxyapatite(334.8 ppm) and Phosphatase activity of Bacillus sphaericus was higher at $35^{\circ}C$ culture condition than that of $25^{\circ}C$. Two type preparation inoculated Bacillus sphaericus made with carrier materials such as Bentonite, $CaCO_3$, Sodium alginate. Density of PSB in this preparation conserved at $10^5c.f.u.\;g^{-1}$ level during storage in different temperature condition for 7 month. It also showed that free phosphate produced at PDA-P medium.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.569-577
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• 2021

CFRP(Carbon Fiber Reinforced Plastic) can maintain the same strength even if the diameter is reduced by about one - third, and the weight is about one - twentieth of that of the deformed reinforcing bars that have been used in the construction industry. In particular, it is resistant to corrosion, which is the weakest part of reinf orcing bars, and there is no concern that it will deteriorate over time, It is light and durable, so transportation costs are low and it is convenient for high-rise buildings. This paper experimentally clarifies the adhesive properties of CFRP and clarifies its behavior. That is, bond strength test was conducted with the directness of CFRP and the strength of concrete as experimental variables, and the bond mechanism was clarified experimentally. Furthermore, based on the experimental results, we constructed the bond stress-slip-strain relationship of CFRP compared to the existing deformed reinforcing bars.

• Journal of Life Science
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• v.28 no.12
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• pp.1424-1431
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• 2018

We prepared flocculated detritus-like organic marine snow originating from various organisms by fermentation using microorganisms; this fermented organic material was fed to the leptocephali of the eel (Anguilla japonica) to investigate whether or not such organic matter was an appropriate food source for the larvae. A strain was isolated from a biofloc technology system used to culture fish, and seven types of organic material from hen's egg, eel muscle, tuna muscle, lugworm, shrimp, manila clam, mussel, and sea squirt were fermented using isolated bacteria (Bacillus sp.). The fermented matter did not show any specific form and was larger than $10-20{\mu}m$ but no more than $100{\mu}m$ in size. Four diets (A-D) were prepared using the various fermented products, and the larvae were fed the prepared food from 20 days after hatching. The leptocephali fed the A, B, and C diets survived until 37, 39, and 37 days after hatching, respectively. However, the leptocephali fed the D diet survived for 60 days after hatching. The protein content of each diet was very similar, but the n-3 HUFA concentration in the D diet was approximately twice as high as that of the others.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.311-318
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• 2018

When reinforced concrete structures are exposed to fire, their mechanical properties such as compressive strength, elasticity coefficient and rebar yield strength, are degraded. Therefore, the structure's damage assessment is essential in determining whether to dismantle or augment the structure after a fire. In this study, the confinement effect of lateral reinforcement of RC column according to the numbers of fire exposure face and stirrup was verified by fire resistant test with the heating temperatures of $400^{\circ}C$, $600^{\circ}C$ and $800^{\circ}C$. The test results showed that the peak stress decreases and peak strain increases as the temperature is getting higher, also transverse ties are helpful in improving the compressive resistance of concrete subjected to high temperature. Based on the results of this study, the residual stress of confined concrete under thermal damage is higher at the condition of more lateral reinforcement ratio and less fire exposure faces. The decreasing ratio of elastic modulus of more confined and less exposure faces from the relationship of load and displacement was also smaller than that of opposite conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.130-134
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• 2019

In this paper, a laser-based non-contact load cell is newly developed for measuring forces in prestressed concrete tendons. First, alumina particles have been sprayed onto an empty load cell which has no strain gauges on it, and the layer has been used as a passive stress sensor. Then, the spectral shifts in fluorescence spectroscopy have been measured using a laser-based spectroscopic system under various force levels, and it has been found that the relation of applied force and spectral shift is linear in a lab-scale test. To validate the field applicability of the customized load cell, a full-scale prestressed concrete specimen has been constructed in a yard. During the field test, it was, however, found that the coating surface has irregular stress distribution. Therefore, the location of a probe has to be fixed onto the customized load cell for using the coating layer as a passive stress sensor. So, a prototype customized load cell has been manufactured, which consists of a probe mount on its casing. Then, by performing lab-scale uniaxial compression tests with the prototype load cell, a linear relation between compression stress and spectrum shift at a specific point where laser light had been illuminated has been detected. Thus, it has a high possibility to use the prototype load cell as a force sensor of prestressed concrete tendons.