• Development and Reproduction
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• v.11 no.2
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• pp.127-135
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• 2007

In order to monitor the developmental features of embryos, larvae, and juveniles of Konoshiro Gizzard Shad Konosirus punctatus, the fertilized eggs were gotton using artificial insemination. Konosirus punctatus were caught in Mankyung-myeon, Kimjae, Jeollabuk-do at June of 2004, and experiments were carried out in Ichthyology laboratory in Chonnam National University. Konosirus punctatus spawned draft egg from March to June. The fertilized eggs were cultured in $19.0{\sim}23.0^{\circ}C$(mean, $21.2^{\circ}C)$. The eggs had spherical shape and the diameter is $1.14{\sim}1.34\;mm$(mean, 1.21 mm). The lens began to appear from 35 hr 53 min after fertilization. At the moment, the movement of larvae was more active, and the tail was separated completely from yolk, the heart had forms, and melanophore appeared. Hatching was observed from 37 hr 10 min after fertilization. The total length of the hatched larvae was $4.26{\sim}5.30\;mm$(mean, 4.96 mm), but the mouth and anus were not opened at the time when the larva had yolk sack, and had $22{\sim}27$ myometium, and the anus located just abdominal front of the tail fin, and melanophore accumulated in the eye. Post-larvae used yolk completely after 2 day of hatching, and the total length was $4.96{\sim}5.74\;mm$(mean, 5.24 mm). From 16 days after hatching, the tail had curved tail end, and appeared the stems for pectoral, dorsal, and caudal fins. At 53 days after hatching, the total length of post-larvae was $27.11{\sim}34.09\;mm$(mean, 30.11 mm), and the frontal part of head developed like an adult one. At this time, fins and body are transferred to those of adult Konosirus punctatus. Fishes have a different shape and location of melanophore even in the same family. This research was tried to elucidate the early developmental features of Konosirus punctatus, together with species-specific pattern of melanophore.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.6
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• pp.773-779
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• 2009

The physicochemical characteristics of abalone meat aged in Kochujang at $20^{\circ}C$ were studied. Moisture contents of Kochujang, which contained raw, roasted, and steamed abalone, increased to 14.9, 10.7, and 7.8%, respectively, compared to control at day 1. The moisture contents of all products were equilibrated at 53.5% approximately after 2 weeks. Hunter's L, a, and b values increased in all products. Total microbial counts were 5.74, 5.70, and 5.83 log CFU/g in the products and increased to 0.28, 0.30, 0.11 log CFU/g, respectively, after 28 days storage at $20^{\circ}C$. After 8 days, the pH in the steamed abalone meat decreased gradually from 5.48 to 5.16 and the titratable acidity was the highest at day 14. Volatile base nitrogens of raw, roast, and steamed abalone were 1.4, 0.9, and 2.7 mg%, but the values in the Kochujang products were 14.0, 13.8, and 11.6 mg% at day 1, and 15.5, 13.3 and 11.3 mg% at day 8, respectively. Quality of the product prepared with steamed abalone was the most acceptable by sensory evaluation.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.10
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• pp.955-965
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• 2014

Transport phenomena of reactant and product are directly linked to intrinsic inhomogeneous random configurations of catalyst layer (CL) that consist of ionomer, carbon-supported catalyst (Pt/C), and pores. Hence, electrochemically active surface area (ECSA) of Pt/C is dominated by geometrical morphology of mass transport path. Undoubtedly these ECSAs are key factor of total fuel cell efficiency. In this study, non-deterministic micro-scale CLs were randomly generated by Monte Carlo method and implemented with the percolation process. To ensure valid inference about Pt/C catalyst utilization, 600 samples were chosen as the number of necessary samples with 95% confidence level. Statistic results of 600 samples generated under particular condition (20vol% Pt/C, 30vol% ionomer, 50vol% pore, and 20nm particle diameter) reveal only 18.2%~81.0% of Pt/C can construct ECSAs with mean value of 53.8%. This study indicates that the catalyst utilization in fuel cell CLs cannot be identical notwithstanding the same design condition.

• Advances in materials Research
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• v.1 no.3
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• pp.221-231
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• 2012

In this study, the physical and mechanical properties of bamboo fiber reinforced epoxy composites were studied. Composites were fabricated using short bamboo fiber at four different fiber loading (0 wt%, 15 wt%, 30 wt% and 45 wt%). It has been observed that few properties increases significantly with respect to fiber loading, however properties like void fraction increases from 1.71% to 5.69% with the increase in fiber loading. Hence, in order to reduce the void fraction, improve hardness and other mechanical properties silicon carbide (SiC) filler is added in bamboo fiber reinforced epoxy composites at four different weight percentages (0 wt%, 5 wt%, 10 wt% and 15 wt%) by keeping fiber loading constant (45 wt%). The significant improvement of hardness (from 46 to 57 Hv) at 15 wt%SiC, tensile strength (from 10.48 to 13.44 MPa) at 10 wt% SiC, flexural strength (from 19.93 to 29.53 MPa) at 5 wt%SiC and reduction of void fraction (from 5.69 to 3.91%) at 5 wt%SiC is observed. The results of this study indicate that using particulate filled bamboo fiber reinforced epoxy composites could successfully develop a composite material in terms of high strength and rigidity for light weight applications compared to conventional bamboo composites. Finally, SEM studies were carried out to evaluate fibre/matrix interactions.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.192-199
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• 2004

Elastic-factor of elastic epoxy were investigated by TMA (Thermomechanical Analysis), DMTA (Dynamic Mechanical Thermal Analysis), TGA (Thermogravimetric Analysis) and FESEM (Field Emission Scanning Electron Microscope) for structure-images analysis as toughness-investigation to improve brittleness of existing epoxy resin. A range of measurement temperature of the TMA and DMTA was changed from -20($^{\circ}C$) to $200^{\circ}(C)$, and TGA was changed from $0^{\circ}(C)$ to $600^{\circ}(C)$. Glass transition temperature (Tg) of elastic epoxy was measured through thermal analysis devices with the content of 0(phr), 20(phr) and 35(phr). Also, thermal expansion coefficient (a), high temperature, modulus and loss factor were investigated through TMA, TGA, and DMTA. In addition, the structure of specimens was analyzed through FESEM, and then elastic-factor of elastic epoxy was visually showed by FESEM. As thermal analysis results, 20(phr) was more excellent than 30(phr) thermally and mechanically. Specially, thermal expansion coefficient, high temperature, modulus, and damping properties were excellent. By structure-images analysis through FESEM, we found elastic-factor of elastic epoxy that is not existing epoxy, and proved high impact.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.31-44
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• 1982

Streptococcus mutans strains were isolated from dental plaques of carious lesions of 53 patients on mitis-salivarius-bacitracin (MSB) and mitis-salivarius(MS) medium as a supplement. The epidemiological investigation was carried out to determine the biotypes and serotypes of S. mutans isolates. For the serotyping, autoclaved extract antigens from the isolates and serotype-specific antisera against seven known serotypes of S. mutans were prepared. The serotypes of the isolates were demonstrated in immunodiffusion test. In addtition, the prevalence of ${\beta}$-hemolysis on 5% sheep blood agar plate in restricted anaerobic condition and yellow pigment production on 5% sucrose agar plate in less anaerobic condition among the isolates were investigated. The results were as follows: 1. Forty-eight S. mutans strains were isolated from dental plaque samples of 33 patients (62.3%) among 53 patients. 2. Of the isolates, some strains were not grown on MSB medium. 3. Serotype c S. mutans was found in 60.6%, serotype d was found in 30.3% of the patients who were known to harbor S. mutans. 4. Of. the isolates, serotype c isolates were most prevalent (43.8%), serotype d isolates were 25.0%, and serotype b, e, f and g isolates were also found but in lower frequencies. Serotype a S. mutans were not detected. 5. The correlation between serotype and biotype of the isolates was found in 78.6% of the typing cases. 6. Strains revealed ${\beta}$-hemolysis were in 52.1% of the isolates, strains produced yellow pigment were in 47.9% of the isolates, and with one exception, all the strains were belong to serotype c, e and f. 7. The majority of the isolates which revealed ${\beta}$-hemolysis appeared to be yellow pigmented, these isolates were belong to serotype c, e and f.

• Mycobiology
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• v.48 no.2
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

• Journal of Conservation Science
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• v.30 no.2
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• pp.169-179
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• 2014

After occurrence of Cyanobacteria in 1997, Songsan-ri tombs located in Gonju have been investigated to monitor for biological damage. The room temperature of Tomb No.6 was $18.6{\sim}19.8^{\circ}C$ and the relative humidity was 94.3~99.9%. The temperature of Royal Tomb of King Muryeong was $17.3{\sim}18.53^{\circ}C$ and the relative humidity was 73.2~96.45%. The variation of relative humidity increased after setting up air vents. If the outside temperature increases, dew condensation occurs on the floor and the north side. When conditioning equipment operates, the maximum temperature differences between walls is $2.8^{\circ}C$. Bacteria from the air of the tomb and on the surface of the walls outnumbered fungi. 20 species of fungi including Alternaria sp., Aspergillus sp., Penicillium sp., and 19 species of bacteria including Pseudomonas sp., Arthrobacter sp., are identified. Microbes in the tombs may damage cultural heritage. The growth possibility of microbes should be estimated because the microbes in the tombs may damage mural painting. The interrelation between microenvironmental condition and biological damage of mural painting should be researched to come up with an long-term conservation method.

• Applied Biological Chemistry
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• v.44 no.2
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• pp.116-121
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• 2001

The compositions of essential oils isolated from the leaves and fruits of Chamaecyparis obtusa (Sieb. et Zucc). Endl. and Chamaecyparis pisifera (Sieb. et Zucc.) Endl. were analyzed through GC and GC-MS. The oil yields were 0.83% (as fresh weight) and 1.36% in the leaves and the fruits of C. obtusa, and were 0.92% and 1.28% in those of C. pisifera, respectively. More than 90 components were identified, including high contents of monoterpenoids and sesquiterpenoids. Contents of monoteipenoids in the leaf and fruit oils of C. pisifera were higher than in those of C. obutsa. The major constituents in the leaf oil of C. obtusa were sabinene (11.81% as determined through GC peak area), limonene (7.73%), bornyl acetate (6.92%), $borneol+{\alpha}-teirineol$ (15.67%), and elemol (12.82%), and those in the fruit oil were myrcene (8.12%), ${\gamma}-terpinene$(5.91%), p-cymene(7.62%), $borneol+{\alpha}-terpineol$(6.53%) and ${\beta}-caryophyllene$ (23.74%). The major constituents in the leaf oil of C. pisifera were ${\alpha}-pinene$(32.34%), ${\delta}-3-carene$(25.28%), myrcene(11.72%), and bornyl acetate (8.77%), and those in the fruit oil were ${\alpha}-pinene$ (29.38%), ${\delta}-3-carene$(30.27%), myrcene(15.05%), and limonene(8.10%).

• Journal of the Korean Chemical Society
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• v.38 no.10
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• pp.719-725
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• 1994

Kinetic studies were carried out for substitution reaction of $cis-[Co(NH_3)_4Cl(OH_2)]^{2+}(\mu$ = 0.75) with GlyOR (R = $C_2H_5$, $CH_3$, H) in pH 5 buffer solution at $20^{\circ}C$ by UV/Vis-spectrophotometry. We obtained cis-[Co$(NH_3)_4$Cl(glyOR)]$^{2+}$ as product. The reaction turns out to be first order for Co(III) and GlyOR, respectively. The rate constants are obtained as 9.21, 11.66 and 15.33 l${\cdot}\;mol^{-1}{\cdot}sec^{-1}$ for GlyOEt, GlyOMt and GlyOH, respectively. The activation parameters $E_a,\;{\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$ for GlyOEt were obtained as 65.77, 63.35 kJ/mol and -53.51(e.u.), respectively and were obtained as 70.91, 68.50 kJ/mol and -38.42(e.u.) for GlyOMt. In case of GlyOH, respectable values of 79.72, 77.30 kJ/mol and -26.59(e.u.) were obtained. On the basis of kinetic data and the observed activation parameters, we propose that the proper mechanism involves $S_N$2 step.