• Korean Journal of Microbiology
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• v.36 no.2
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• pp.119-124
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• 2000

Thirty three strains of bacteria were isolated from the wastewater and soil contaminated a chemical softener, nrganopolysiloxane. Of these, five strains which showed higher activities for removal this chemical were finally selected for further study. By five strains the 2,500 mgll chemical softener was removed 65.2-67.9% at $37^{\circ}C$ for 5 days by shaking. The pH optimum for growth of W3721, S3712, and S3723 strain were at around pH 7.0-7.5, and W2811, and W2823 strain were at pH 6.5-7.0, respectively. The temperature optimum for growth of W3712 strain was at $37^{\circ}C$ and the other four strains were at TEX>$30^{\circ}C$. The optimal pH and temperature for removal by W3712 strain was initial pH 7.0 and $37^{\circ}C$ respechvely. The W3712 strain was identified and named as Corynebacterium pseudodiphtheriticum W3712 based on its morphological and physiological characteristics.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.87-94
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• 1986

This study was performed in order to contemplate their correlations between physical and mechanical properties of the marine clays which were collected from main harbors in Korea. The results obtained are as follows: 1. Most of the soils in experimental districts consist of CH. CL. and ML. and they are considered to be still proceeding. 2. The equations of the relationship between compression index and liquid limit are as, follows: CH : $C_c=0.0137$ (LL-22.60) CL : $C_c=0.0123$ (LL-14.64) 3. The relationship between compression index and initial void ratio appears that the higher the plasticity, the easier the slope of the regression line. The equations are as follows : CH : $C_c=0.431$ ($e_o-0.504$) CH : $C_c=0.471$ ($e_o-0.235$) ML : $C_c=0.641$ ($e_o-0.393$) 4. The equations of the relationship between compression index and natural water content are as follows: CH : $C_c=0.0133$ ($W_n-28.27$) CL : $C_c=0.0225$ ($W_n-23.56$) ML : $C_c=0.0106$ ($W_n-16.42$) 5. The relationship between initial void ratio and natural water content, and compression index is highly positive correlation and the equations are as follows : CH : $C_c=0.301$ ($e_o+0.017W_n-1.05$) CL : $C_c=0.141$ ($e_o+0.0567W_n-1.054$) ML : $C_c=0.421$ ($e_o+0.0214W_n-1.121$) 6. The equations of the relationship between initial void ratio and liquid limit, and compression index are as follows : CH : $C_c=0.36$ ($e_o+0.08LL-0.819$) CL : $C_c=0.269$ ($e_o+0.026LL-0.929$) 7. The cohesion of marine clays is no concerned with the increment of depth. The equations of relationship between cohesion and unconfined compression strength are as follows. CH : qu=1.896C+0.0107 CL : qu=1.849C+0.04.

• KSBB Journal
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• v.15 no.1
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• pp.27-34
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• 2000

A marine bacterium having a high oil-degrading activity was isolated form the oil-polluted southern sea of Korea, and was identified as Pseudomonas aeruginosa and was named Pseudomonas aeruginosa BYK-2. The optimal tmeperatur, culture time, pH and NaCl concentration for biosurfactant production and cell growth showed $25^{\circ}C$, 48h, 7.0 and 0%(w/v), respectively. After cultivation at $25^{\circ}C$, 180 rpm in 250 mL erlenmeyer flask for 7days, 1%(w/v) arabian light crude oil and bunker C oil which are considered to be hardly degradable compounds were degraded 92.1%(w/w) and 76%(w/w) respectively. And then, cell adherence was measured on various carbon sources. The cell adherence indicated over 80% on hydrocarbons(arabian light crude oil, kuwait curde oil, bunker C oil, n-paraffine, n-hexadecane, n-tetradecane) as carbon sources. Lecithin among fatty acids(oleic acid, olive oil, lecithin) showed highest cell adherence of 91.5%. The cell adherence of sugars(arabinose, trehalose, dextrose, galactose, lactose, fructose, maltose, sorbitol, sucrose) observed to be less than 70% except for arabinose, galactose, sorbitol and sucrose.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.1
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• pp.29-37
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• 2004

The effect of the substitution of Tungsten(W) for Molybdenum(Mo) on the creep behaviour of 22Cr-5Ni duplex stainless steel(DSS) has been investigated. Creep tests were carried out at $600^{\circ}C\;and\;650^{\circ}C$. Intermetallic ${\sigma}$ phase is precipitated during creep at $650^{\circ}C$, at which creep rupture time was much lower compared with at $600^{\circ}C$. The substitution of W for Mo in the duplex stainless steel was known to retard the formation of ${\sigma}$ phase. Minimum creep rate and creep rupture time, however, were hardly influenced by the substitution of 2wt.% W. An ultrasonic measurement for the creep specimens has been carried out for the evaluation of creep damage. The sound velocity increases propotionally with the increase of creep rupture time at $600^{\circ}C$ of creep temperature. On the contrary, the sound velocity decreases with the increase of rupture time at $650^{\circ}C$, which can be correlated with the microstructural evolution during creep.

• KSBB Journal
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• v.9 no.4
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• pp.436-442
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• 1994

The production of itaconic acid by Aspergillus terreus NRRL 1960 was studied. The optimal culture conditional such as pH, inoculum size and medium composition were established. Maximum production of itaconic acid, $19.18g/\ell$, was obtained when the cultivation was carried out at $37^{\circ}C$ and pH 2.5 for 7days, with medium containing 5%(w/v) glucose, 0.5%(w/v) NH4Cl, 0.2%(w/v) yeast extract 0.1%(w/v) CaC12, 0.1%(w/v) MgSO4 and 0.2%(w/v) NaCl. A proper medium for inoculum culture was found to be 2%(w/v) malt extract. The batch production of itaconic acid with free cells in a stirredtank reactor was not efficient compared to the shake-flask culture.

• Nuclear Engineering and Technology
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• v.5 no.1
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• pp.3-12
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• 1973

Some physical and chemical properties of wood-plastic combinations(W.P.C.) made of domestic soft woods such as pinus densiflora, pinus rigida and poplus deltoides were measured. The rates of improvement in properties were roughly proportional to the contents of polymer or polymer mixtures in W.P.C. For the W.P.C. obtained by means radiation curing and containing 80% of polymer or polymer mixture, the hardness and water absorptirity were improved 2.2 times and 4 times those of the original wood, respectively. The improvement of hardness was especially remarkable in the W.P.C. made of pinus densiflora and polystyrene(120%) to show 7 times increased hardness. For the W.P.C. obtained by means of thermal curing and containing 80% of polymer or polymer mixture, the hardness and water absorptivity were improved 2.4 times and 3.4 times those of the non-treated woods, respectively. These data indicate that the properties of W.P.C. prepared by means of radiation curing are not much different from those of W. p. C. prepared by means of thermal curing. Both of acid resistancy and alkali resistancy of the W.P.C. were also improved remarkably in comparison with the non-treated wood.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.4
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• pp.165-170
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• 2018

W, Fe, and carbon powders were mechanical alloyed to produce $W_{35}Fe_{43}C_{22}$ ternary alloy powders containing nanocrystal W embedded within amorphous matrix. When the powder samples were heated to the primary crystallization temperature of $735^{\circ}C$, most parts of their amorphous region were fully crystallized to [W,Fe]-rich $M_6C$ carbides. Interestingly, a little portion of the carbides changes to stoichiometric line compounds ($M_{12}C$ and $W_6Fe_7$) and a solution phase (Fe-rich bcc), and remaining parts of the crystallites were amorphized again. The resulting microstructure was retained even by cyclic heating between room temperature of $1,200^{\circ}C$, and thus we found that the amorphous structure can be irreversibly formed at above glass transition temperature.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.854-860
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• 2018

In spite of the many attractive properties of (W,Ti)C, its low fracture toughness limits its wide application. To improve the fracture toughness generally a second phase is added to fabricate a nanostructured composite. In this regard, graphene was considered as the reinforcing agent of (W,Ti)C. (W,Ti)C-graphene composites that were sintered within 2 min using pulsed current activated heating under a pressure of 80 MPa. The rapid consolidation method allowed retention of the nano-scale microstructure by blocking the grain growth. The effect of graphene on the hardness and microstructure of the (W,Ti)C-graphene composite was studied using a Vickers hardness tester and FE-SEM. The grain size of (W,Ti)C was reduced remarkably by the addition of graphene. Furthermore, the hardness decreased and the fracture toughness improved with the addition of graphene.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.3
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• pp.536-543
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• 1997

The subjects wearing cool clothing (C group) or warm clothing (W stoup) in daily life from September to February of the following year were tested to examine whether cold acclimatization takes place by clothing habits. Subjects rested at 25$\pm$1$^{\circ}C$, then were exposed to 15$\pm$1$^{\circ}C$, 50$\pm$5% R.H. for 90 min in September, November, December, and February. Rectal temperature (Tre) of C group after 90 min cold exposure did not drop below the Tre in $25^{\circ}C$ throughout the study. W group's Tre, however, dropped below the temperature in 25t from December. Shivering stopped after December in C group while W group continued to show it for the whole study. In resting, C group showed higher heat production than W group in February, and the rate of increase in heat production during cold exposure was smaller in C group than W group in February. C group showed less cold sensation than W group in the same coldness. These results suggest that the level of cold acclimatization may be improved by the habits wearing less clothes in daily life.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.3
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• pp.187-198
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• 1970

The author succeeded in rearing the young blue crab from the first stage of zoe ato the true crab shape, and during this time he observed their growth and metamorphosis. The relationships between the number of eggs carried by female crabs (E) and the carapace width (C) and body weight (W) are shown as follows: E= 27.9049C-281.8155, E=0.5682 W-116.4606. There are five zoeal stages and a megalopa in the complete larval development of the blue crab. Water temperature in rearing aquaria ranged from 21.4 to $25.2^{\circ}C$. The duration of each zoeal stage was two days on the average. After the fifth moulting, the zoea becomes megalopa and 5 to 6 days later the megalopa moults and develops into the first stage of adult crab shape. The carapace width of megalopa measured about 1.70 mm and the carapace length, from the tip of the rostrum to the posterior dorsal margin of the carapace, was about 2.78 mm on the average. The carapace width and length of the first crab, 18 days after hatching, measured about 4.48 mm and 2.62 mm respectively. After two days, the first crab moulted and grew into the second crab with about 6.47 mm in carapace width and 4.66 mm in carapace length. The larval rearing in the outdoor tank shelved better results than in the indoor aquarium. The highest mortality occurred when the first stage of zoea moulted into the second stage. Percentage of crabs which survived, from the first crab to the ninth crab stages, was about $55\%$. The relationships between rearing days (D) and the carapace width (C), carapace length (L) and body weight (W) of the crab stages during 40 days of rearing are shown as follows. Carapace width, Indoor: C=1.1250D+1.7227 Outdoor C=1.3465D -0.2449 Carapace length, Indoor: L=0.6654D+1.6712 Outdoor: L=0.7893D+0.6919 Body Weight, Outdoor: $$W=1.15e^{0.12423D}$$ Indoor: $$W=6.759\times10^{-2}D^{1.2598}$$ (9-19 day old crabs) Outdoor: $$W=4.136\times10^{-2}D^{1.6024}$$ (21-40 day old crabs) During the crab stage, the following relationships between the number of moulting times and the carapace width (C), carapace length (L) and body weight (W) were found as follows: $$C=5.2e^{0.28119N}$$ $$L=3.65e^{0.26372N}$$ $$W= 0.14e^{0.7037N}$$ The relationships between the carapace length (L) and the carapace width (C) and body weight (W) of the crab stages are shown as follows: Carapace length, mm Formula 2.62-27.17 L=1.6864C-1.0387 7.47-18.53 $$W=9.367\times10^{-5}C^{3.5567}$$ 22.11-27.17 $$W=3.406\times10^{-5}C{3.8571}$$