• Elastomers and Composites
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• v.43 no.3
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• pp.173-182
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• 2008

Rubber-pad forming process for materials such as metal in which portions of the die which act upon the material is composed of a natural or synthetic rubber or elastomer material. This makes the rubber pad forming process relatively cheap and flexible, high accuracy for small product series in particular. In this study, we carried out the physical test and finite element analysis of elastomer such as natural rubber and urethane for steel rack rube forming. The non-linear property of elastomer which are described as strain energy function are important parameter to design and evaluate of elastomer component. These are determined by material tests which are uni-axial tension and bi-axial tension. This study is concerned with simulation and investigation of the significant parameters associated with this process.

• Korean Journal of Veterinary Research
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• v.55 no.2
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• pp.81-88
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• 2015

This study was conducted to isolate lactic acid bacteria (LAB) from dog intestine and identify potential probiotic strains for canine use. One hundred and one LAB were isolated from feces of 20 healthy dogs. Acid, bile, and heat resistance along with adherence to Caco-2 cells and antimicrobial activity against pathogens were examined. To analyze immunomodulative effects, the production of nitric oxide (NO), TNF-${\alpha}$, and IL-$1{\beta}$ was measured using RAW 264.7 macrophages. Additionally, RAW BLUE cells were used to evaluate nuclear factor-${\kappa}B$ (NF-${\kappa}B$) generation. Ultimately, three strains were selected as canine probiotics and identified as Lactobacillus reuteri L10, Enterococcus faecium S33, and Bifidobacterium longum B3 by 16S rRNA sequence analysis. The L10 and S33 strains showed tolerance to pH 2.5 for 2 h, 1.0% Oxgall for 2 h, and $60^{\circ}C$ for 5 min. These strains also had strong antimicrobial activity against Escherichia coli KCTC 1682, Salmonella Enteritidis KCCM 12021, Staphylococcus aureus KCTC 1621, and Listeria monocytogenes KCTC 3569. All three strains exerted better immunomodulatory effects than Lactobacillus rhamnosus GG (LGG), a well-known commercial immunomodulatory strain, based on NO, NF-${\kappa}B$, IL-$1{\beta}$, and TNF-${\alpha}$ production. These results suggested that the three selected strains could serve as canine probiotics.

• Food Science of Animal Resources
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• v.31 no.5
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• pp.719-726
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• 2011

Pediococcus pentosaceus JWS 939 (JWS 939) is a nonpathogenic bacteriocin-producing probiotic isolated from the duck intestine. This study assessed the immunomodulatory effects of JWS 939 and compared them with those of Lactobacillus rhamnosus GG (LGG), a well-known immune enhancer. The immune-enhancing effects of JWS 939 were measured by measuring the production of nitric oxide (NO) and cytokines in C57BL/6 mouse peritoneal macrophages. In addition, to assess the immune enhancement abilities of JWS 939, in vivo, a Listeria monocytogenes challenge mice model was used. The results showed that heat-killed JWS 939 induced more NO and interleukin (IL)-$1{\beta}$ production in mouse peritoneal macrophages than in LGG, and that oral administration of viable JWS 939 in mice increased more NO, IL-$1{\beta}$, and tumor necrosis factor (TNF)-${\alpha}$ level than in LGG in serum upon L. monocytogenes challenge. In addition, mice fed with JWS 939 had a longer survival time after lethal challenge with L. monocytogenes, and these effects were stronger than those induced by LGG. Collectively, P. pentosaceus JWS 939 is a remarkable strain that, by releasing bacteriocin and enhancing host immune responses, may have potential as a duck feed additive to suppress pathogens.

• Geotechnical Engineering
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• v.12 no.2
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• pp.59-70
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• 1996

The EPS has the unit weight of only 20~30kg/m3 and is used as one of the methods of reducing road embankment loads. Parts of it's applications are for backfill materials of structures like abutment, retaining wall, etc., to reduce horizontal earth pressure and for banking materials to secure the safety of settlement and bearing capacity by minimizing the stress Increment. However, the Korean Standards (KS) has not yet proposed any testing method for use of EPS as a engineering banking material. Only its testing and quality ordinance as a heat insulation material has been standardized. Therefore, in Korea, EPS is used as banking material without any systematic testing data as a civil engineering material. In this point of view, this paper deals with the engineering characteristics of EPS through many laboratory tests on strength, strain, absorption, and creep. from the results achived through tests, this paper proposes the enactment of a suitable quality testing ordinance and the criteria of unconfined design strength of EPS for use as engineering material.

• BMB Reports
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• v.41 no.2
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• pp.119-125
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• 2008

Our previous work confirmed that Sph2/LA1029 was a sphigomyelinase-like hemolyisn of Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai. Characteristics of both hemolytic and cytotoxic activities of Sph2 were reported in this paper. Sph2 was a heat-labile neutral hemolysin and had similar hemolytic behavior as the typical sphingomyelinase C of Staphylococcus aureus upon sheep erythrocytes. The cytotoxic activity of Sph2 was shown in mammalian cells such as BALB/C mouse lymphocytes and macrophages, as well as human L-02 liver cells. Transmission electron microscopic observation showed that the Sph2 treated BALB/C mouse lymphocytes were swollen and ruptured with membrane breakage. They also demonstrated condensed chromatin as a high-density area. Cytoskeleton changes were observed via fluorescence confocal microscope in Sph2 treated BALB/C mouse lymphocytes and macrophages, where both cytokine IL-$1{\beta}$ and IL-6 were induced. In addition, typical apoptotic morphological features were observed in Sph2 treated L-02 cells via transmission electron microscope and the percentage of apoptotic cells did increase after the Sph2 treatment detected by flow cytometry. Therefore, Sph2 was likely an apoptosis-inducing factor of human L-02 liver cells.

• Preventive Nutrition and Food Science
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• v.10 no.4
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• pp.333-339
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• 2005

Three lactobacillus strains, two from infant feces, and one from cow's milk, were selected among 172 isolates, from multiple sources, for further study based on the antimicrobial activities against six strains of pathogenic bacteria and identified as Lactobacillus acidophilus. The strains revealed a wide scope of spectrum against pathogenic bacteria. Viable Lactobacillus acidophilus KH-l cell counts at pH 2.0 were slightly decreased to $1.42\times10^7$ CFU/mL from $4.18\times10^7$ CFU/mL, while remaining at $3.42\times10^7$ CFU/mL at pH 4.0 with the survival rate of $33.97\%\;and\;81.82\%$, respectively. At the concentration of $0.1\%$ oxgall, L acidophilus KH-l kept growing up to $3.12\times10^7$ CFU/mL with a mean growth rate constant (k) of 0.25, and cell number was slightly decreased to $1.21\times10^7$ CFU/mL (k=0.19) with $0.3\%$ oxgall, but remained at $7.6\times10^6$ CFU/mL (k=0.17) with $0.5\%$ oxgall. L. acidophilus KH-l had a $D_{60}$ value of 7.14, with viable cell numbers $1.4\times10^5$ CFU/mL after heat treatment at $60^{\circ}C$ for 30 minutes. Stability of L acidophilus KH-l at $-20^{\circ}C$ was significantly higher, when the strain was cultivated under the optimum growth temperature $(54.41\%\;and\;54.35\%)$ than at the temperature $(13.53\%)$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1557-1566
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• 2004

A flame extinction phenomenon is a typical unsteady process in combustion. Flame extinction is characterized by various physical phenomena, such as convection, diffusion, and the production of heat and mass. Flame extinction can be achieved by either increasing the strain rate or curvature, by diluting an inert gas or inhibitor, or by increasing the thermal or radiant energy loss. Though the extinction is an inherently transient process, steady and quasi-steady approaches have been used as useful tools for understanding the flame extinction phenomenon. Recently, unsteady characteristics of flames have been studied by many researchers, and various attempts have been made to understand unsteady flame behavior, by using various extinction processes. Representative parameters for describing flame, such as flame temperature, important species related to reactions, and chemi-luminescence of the flame have been used as criterions of flame extinction. In these works, verification of each parameter and establishing the proper criterions of the extinction has been very important. In this study, a time-dependent flame temperature and an OH radical concentration were measured using optical methods, and the instantaneous change of the flame luminosity was also measured using a high-speed ICCD (HICCD) camera. We compare the unsteady extinction points obtained by three different methods, and we discuss transient characteristics of maximum flame temperature and OH radical distribution near the extinction limit.

• Korean Journal of Microbiology
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• v.16 no.2
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• pp.47-61
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• 1978

Strptomyces albus T-12 which ahd been isolated and identified in the laboratory, was selected for the studies on the cultural conditions on the production of D-xylose iosmerase and the enzymological characteristics using the partially purified enzyme. The best results in the enzyme production came from D-xylose medium than wheat bran. The divalent metla ions as $Co^{2+},\;Fe^{2+},\;Zn^{2+}\;and\;Cu^{2+}$ retard or inhibit the cell-growth at the early stages of mycelia propagations, and T-12 strain is especially sensitive to $Co^{2+}$. After 60 hours of shaking cultivation at $30^{\circ}C$ and 200 rpm, a maximum enzyme activitz, 0.49 enzyme units, was obtained. Cell-free enzyme obtained from mycelia heat-treated in the prescence of 0.5mM $Co^{2+}$, showed a 2.4-fold increase in specific than the enzyme from untreated mycelia. The specific activity of the purified enzyme through Sephadex G-150 columm showed 180 fold to the crude enzyme. The effective activators of the enzyme appeared to be $Mg^{2+}\;and\;Co^{2+}$ ions, and it exhibited the maximal enzyme activity showed at pH 7.0 and at tempersture around $80^{\circ}C$ when $Mg^{2+}\;and\;Co^{2+}$ ions were added. The enzyme isomerized D-glucose, D-xylose, D-ribose, L-arabinose, D-mannose, and L-rhamnose in the present of $Mg^{2+}\;and\;Co^{2+}$ ions as an activatiors. $Mg^{2+}\;and\;Co^{2+}$ ions were non-competitively bound at different allosterix sites of enzyme molecule. $Mg^{2+}(5mM)\;or\;Co^{2+}(1.0mM)$ protected against the thermal denaturations of the enzyme activities. The michelis constant(Km) and $V_{max}$ values of the emzyme for D-glucose and D-xylose were 0.52M, $2.12{\mu}moles/ml{\cdot}min.\;and\;0.28M,\;0.65moles/ml{\cdot}min.$, respectively.

• Journal of the Korean Society of Combustion
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• v.21 no.1
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• pp.38-45
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• 2016

Flame characteristics and NO emission behavior in $CH_4$/air-air premixed counterflow flames with applying FIR and FGR with $CO_2$ and $H_2O$ were investigated numerically by varying the ratios of FIR and FGR as well as global strain rate. Chemical effects of added $CO_2$ and $H_2O$ via FIR and FGR were analyzed through comparing flame characteristics and NO behaviors from real species($CO_2$ and $H_2O$) with those from their artificial species($XCO_2$ and $XH_2O$) which have the same thermochemical, radiative, and transport properties to those for the real species. The results showed that flame temperature and NO emission with FIR varied much more sensitively than that with FGR. Those varied little irrespective of adding $CO_2$, $H_2O$, and their artificial species to the fuel stream via FIR. However, Those were varied complicatedly by chemical effects of added $CO_2$ and $H_2O$ via FGR. Detailed analyses for them were made and discussed.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.7
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• pp.1129-1136
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• 2008

The gaiter is one of the personal protective equipments worn in various industrial sites. This study was performed on humans to investigate the physiological strain of wearing gaiters and to compare control gaiters that are currently on the market and new gaiters that are developed for alleviating heat stress. Experiments were conducted in a climatic chamber of WBGT $30.0\pm0.7^{\circ}C$ under five differed experimental conditions: None, Control A, Control B, New A, New B. The results were as follows. The temperature inside gaiters was significantly lower in both New A and New B than in both Control A and Control B and the difference between news and controls was 1$^{\circ}C$ (p<.01). The humidity inside gaiters in both New A and New B were higher than that in Control A, and lower than that in Control B (p<.01). The outermost surface temperature of the gaiter was the lowest in None and it increased in the following order: New B < New A < Control A < Control B. Mean skin temperature was higher by 0.14$^{\circ}C$ in wearing gaiters than in no gaiters. Skin temperatures in lower body were lower in Control than in New and skin temperature in upper body were higher in Control than in New (p<.01). Local sweat rate, total weight loss and subjective sensations did not show a significant difference according to the gaiters. It was concluded that wearing gaiters affected distribution of skin temperature and local sweat rate.