• KSBB Journal
• /
• v.17 no.6
• /
• pp.531-536
• /
• 2002

In this study, we attempted to increase the survivability of bifidobacteria in simulated gastric juices and bile salts after cell entrapment with alginate and various food additives, such as erythritol, isomalt, palatinose, skim milk, xanthan gum, isomalto-oligosaccharide, fructo-oligosaccharide, galacto-oligosaccharide, pectin, and mono-sodium glutamate. Additionaly, the stability of bifidobacteria during storage was investigated by measuring survival rate at different temperatures, i.e. at 4$^{\circ}C$, 25$^{\circ}C$ and -20$^{\circ}C$. Bifidobacteria were immobilized in alginate beads and the survival rate was monitored. It was found that bifidobacieria entrapped with 2.5％, alginate showed the highest survival rate at 12%. After addition of the various protective agents, erythritol(1％) showed the best protective efficiency with a survival rate of 56.0% among the additives tested when exposed to simulated gastric juices for 3 h. Immobilized cells suspended in 5% skim milk and stored at 4$^{\circ}C$ survived significantly more than cells stored at 25$^{\circ}C$ and -20$^{\circ}C$. Consequently, the study shows that the survival rate of bifidobacteria immobilized in combination with 2.5% alginate beads and 1% erythritol may be signifcantly increased in simulated gastric juices and bile salts.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.1
• /
• pp.51-56
• /
• 2012

Crashworthy fuel cells have been widely implemented to rotorcraft and rendered a great contribution for improving the survivability of crews and passengers. Since the embryonic stage of military rotorcraft history began, the US army has developed and practised a detailed military specification documenting the unique crashworthiness requirements for rotorcraft fuel cells to prevent most fatality due to post-crash fire. Foreign manufacturers have followed their long term experience to develop their fuel cells, and have reflected the results of crash impact tests on the trial-and-error based design and manufacturing procedures. Since the crash impact test itself takes a long-term preparation efforts together with costly fuel cell specimens, a series of numerical simulations of the crash impact test with digital mock-ups is necessary even at the early design stage to minimize the possibility of trial-and-error with full-scale fuel cells. In the present study a number of numerical simulations on fuel cell crash impact tests are performed with a crash simulation software, Autodyn. The resulting equivalent stresses are further analysed to evaluate a number of appropriate design parameters and the artificial neural network and simulated annealing method are simultaneously implemented to optimize the crashworthy performance of fuel cells.

• Korean Journal of Food Science and Technology
• /
• v.28 no.3
• /
• pp.451-457
• /
• 1996

The effects of pH and L-cysteine HCI on the growth and stability of Biofidobacterium breve were studied. Significantly higher population was obtained by culturing at pH $6.0{\sim}6.5$ than at any other pH. The cultures that had been grown at pH $5.5{\sim}6.0$ were more stable during storage than those grown at other pH. The number of B. breve that had been grown at pH 5.5 and 6.0 remained as $2.4{\times}10^6ml/\;and\;1.4{\times}10^6ml,$ respectively, after 25 days of storage at $4^{\circ}C$. The ${\beta}$-galactosidase activity of B. breve grown at pH 5.5 and 6.0 was reduced only to $78{\sim}85%$ of the control after the same storage condition, whereas the culture grown at pH 7.0 exhibited a signficant decline in population and ${\beta}$-galactosidase activity during $4^{\circ}C$. The growth of B. breve was promoted by 0.05% L-cysteine HCI, and cells grown in MRS with $0.05{\sim}0.10%$ L-cysteine HCI were more resistant to hydrogen peroxide. With respect to the effect to the effect of osmoprotectants on the survival of B. breve subjected to freeze-drying, addition of 2 mM betaine of 2 mM trehalose increased the growth rate of cells grown under osmotic stress and also made the organism more osmotolerant. Furthermore, the betaine or trehalose increased the survivability of the cells after freeze-drying.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.5
• /
• pp.495-501
• /
• 2015

Abroad warships are confronted with various menaces. The most critical threat of the warship is an Anti-Ship Missile (ASM). The ASM is able to be launched at a variety of environments and platforms. The ASM can evades conventional naval radar systems and electronic countermeasure techniques for providing a fatal damage to the warship. To cope with the ASM, an active decoy is an effective method to minimize the direct damage to the warship. The active decoy increases survivability of the warship because the ASM can lure pursuit of the active decoy instead of the warship. In this paper, our proposed method verifies an available response time of the active decoy to deal with the ASM using the active decoy of the warship in marine environments. We defined models of the warship, the ASM, and the active decoy, and executed simulation by combining the models. By the simulation result, the proposed method demonstrated the superiority of the mobile active decoy of the response time decoy among various active decoys, and estimated a protection area to prevent the ASM according the response time of the mobile active decoy against the ASM.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.2
• /
• pp.71-78
• /
• 2014

There is a big risk of bullet impact because military rotorcraft is run in the battle environment. Due to the bullet impact, the rapid increase of the internal pressure can cause the internal explosion or fire of fuel cell. It can be a deadly damage on the survivability of crews. Then, fuel cell of military rotorcraft should be designed taking into account the extreme situation. As the design factor of fuel cell, the internal fluid pressure, structural stress and bullet kinetic energy can be considered. The verification test by real object is the best way to obtain these design data. But, it is a big burden due to huge cost and long-term preparation efforts and the failure of verification test can result in serious delay of a entire development plan. Thus, at the early design stage, the various numerical simulations test is needed to reduce the risk of trial-and-error together with prediction of the design data. In the present study, the bullet impact numerical simulation based on SPH(smoothed particle hydrodynamic) is conducted with the commercial package, LS-DYNA. Then, the resulting equivalent stress, internal pressure and bullet's kinetic energy are evaluated in detail to examine the possibility to obtain the configuration design data of the fuel cell.

• Journal of Life Science
• /
• v.9 no.3
• /
• pp.333-340
• /
• 1999

The toxic effect of TBTO on Chlorella and Rotifer was observed. The value of 48hr-LC50 for Chlorella (3.3$\mu\textrm{g}$/L) estimated to be almost 500 times as high as that for Rotifer (6.7ng/L). A fertilized egg of olive flounder exposed in an embryo-formation stage was mostly influenced by TBTO toxicity when the fertilized egg at each stage until hatching was exposed to TBTO at the concentrations of 5 to 200ng/L. The values of LT50 were estimated to be 68.0, 41.0, 21.0, 13.0, 7.7 and 4.7 hours at 5, 10, 25, 50, 100 and 200ng/L of TBTO, respectively when the fertilized egg in a morula stage was exposed to TBTO, and the 48hr-LC50 was 8 ng/L. In case of TBTO treatment in an embryo-formation stage, the values of LT50 were 33.0, 12.5, 3.5, 1.3, 0.5 and 0.2 hours at 5, 10, 25, 50, 100 and 200ng/L of TBTO, respectively, and the value of 48hr-LC50 was 4ng/L. The values of LT50 were estimated to be 17.0, 11.0, 6.2, 4.0, 2.6 and 1.7 hours at 5, 10, 25, 50, 100 and 200ng/L of TBTO, respectively when the fertilized egg in a stage just before hatching was exposed to TBTO, and the 48hr-LC50 was below 1ng/L. The percentages of hatching were 46.2, 20.6, 21.9, 20.6 and 13.2% at 25, 50, 100, 250 and 500ng/L of TBTO, respectively when the fertilized egg in the stage just before hatching was exposed to TBTO and the measurement was done at second day after the completion of hatching. However no survival after the completion of hatching was found in all cases. With the treatment of 1, 5 and 10ng/L of TBTO, the percentages of hatching were 80.5, 70.0 and 44.1%, respectively. The percentages of survival until second day after the completion of hatching were 80.0, 63.3 and 9.1%, respectively. The percentages of hatching and survivability after the completion of hatching for the control were 84.5 and 82.5%, respectively.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.7
• /
• pp.936-944
• /
• 2019

Submarines, which have been called an invisible force, are strategic underwater weapon systems that perform missions such as anti-surface warfare, anti-submarine warfare, and high payoff target strikes with the advantage of underwater covertness. A submarine should be able to withstand the hydrostatic pressure of the deep sea. In this respect, the submarine pressure hull, as the main structural system to resist the external pressure corresponding to the submerged depth, should ensure the survivability from hazards and threats such as leakage, fires, shock, explosion, etc. To do this, the initial scantling of the submarine pressure hull must be calculated appropriately in the concept design phase. The shape of the aft transition ring varies according to its connection with the submarine aft end conical structure, pressure hull cylindrical part, and non-pressure hull of the submarine; the design of the aft transition ring should not only take into account stress flow and connectivity but also the cost increase due to the increased man-hours of its complex geometry. Therefore, trade-off studies based on the four different shapes of the aft transition ring are carried out considering both the review of the structural strength through nonlinear finite element analysis (FEA) and economic feasibility by reviewing the estimations of the manufacturing working days and material costs. Finally, the most rational structural aft transition ring shape for a submarine amongst four reviewed types was proposed.

• Journal of the Korea Institute of Building Construction
• /
• v.16 no.1
• /
• pp.77-85
• /
• 2016

This study provides the numerical model to assess retrofit and strengthen levels in the dispersal and combat facilities. First of all, it is verified that direct-hitting projectiles are more destructive to the structures rather than close-falling bombs with explosion tests. The protective capacity of dispersal and combat facilities, which are modeled with soil uncertainty and structural field data, is analyzed through finite element method. With structural survivability and facility data, the logistic regression model is drawn. This model could be used to determine the level of the retrofit and strengthen in the dispersal and combat facilities of contact areas. For more reliable model, it could be better to identify more significant factors and adapt non-linear model. In addition, for adapting this model on the spot, appropriate strengthen levels should be determined by hands on staffs associated with military facilities.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.12
• /
• pp.1070-1079
• /
• 2012

The impact energy absorbing is a very important characteristic of an aircraft to enhance the survivability of occupants when an aircraft is under the survivable accident such as an emergency landing condition. The impact energy is generally transmitted into the occupant and absorbed through a landing gear, a subfloor (lower structure of fuselage), and a seat. The characteristic of crash energy absorbing of a subfloor depends on the type of an aircraft, a shape of structure, and an applied material. Therefore, the study of crashworthiness characteristics of a subfloor structure is very important work to improve the safety of an aircraft. In this study, a finite element model of a narrow body fuselage section for the 80~90 seats regional aircraft was developed and crash simulation was executed using an explicit finite element analysis. Through survey of the impact energy distribution of each structural part of a fuselage and floor-level acceleration response, the crashworthiness characteristics and performance was evaluated.

• Applied Biological Chemistry
• /
• v.49 no.3
• /
• pp.170-174
• /
• 2006

For the purpose of developing a high quality agricultural microbial inoculant, methods and materials for improving encapsulation were investigated. Preparation of capsule was conducted by improving extrusion system with micro-nozzle and peristaltic pump. The sodium alginate was selected because of its cheapness, stability of cells, and gel formation ability. The yields, physical properties and gel formation abilities of extractable alginate from sea tangle were investigated by hot water extractable and alkali soluble methods. The extraction yields of hot water extractable alginate (HWEA) and alkali soluble alginate (ASA) from sea tangle were 8 and 20%, respectively. The HWEA was almost not viscous even in 1.5% of the sample solution, whereas the ASA was very highly viscous in above 3% sample solution. The gel formation ability of each samples varied from 1.5% to 5% and the ASA showed a good gel formation ability at 3% solution as commercial alginate (CA). The soil microbial inoculant, Bacillus thuringiensis, Bacillus subtilis, Lactobacillus plantarum and Geotrichum candidum encapsulated sodium alginate with starch and zeolite for stabilizer. The survivability of encapsulated soil microbial inoculant using alginate without stabilizer appeared to be 66, 52, 70 and 50%, respectively. Inclusion of starch and zeolite with alginate bead increased viabilities in Bacillus sp. and Geotrichum candidum by 81-83% and 89%, respectively.