• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.821-828
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• 2005

To investigate the role of RH and temperature on the transport of chloride in the concrete, two groups of specimens were configured. For both groups, mix design was based on w/c=0.45, $400kg/m^3$ cement, $794kg/m^3$ fine aggregate and $858kg/m^3$ coarse aggregate. After specimen fabrication these were exposed to four different RH (35, 55, 75 and $95\%$ RH) and temperature (0, 20, 30 and $40^{\circ}C$) conditions. After 3 and 6 months $15\%$ NaCl exposure 5mm cores were taken. These cores were sliced and individual cores were ground to powder. In addition, to evaluate the effect of temperature on the chloride binding some powder samples were leached in the each of four temperature chambers. Chloride titration fur these was performed using FDOT acid titration method. Based upon the resultant data conclusions were reached regarding that 1) effective diffusion coefficient, $D_e$, increased with increasing exposure RH, suggesting that the size and number of water paths increased with elevated moisture content in the specimens, 2) $D_e$ increased with increasing temperature in the range of 0 to $40^{\circ}C$ possibly by elevated thermal activation of chloride ions and reduced chloride binding at higher temperature, 3) water soluble chloride concentration, $[Cl^-]_s$, increased with increasing temperature, and 4) chloride concentration profile for initially dry concrete specimens was higher than for the initially wet ones indicating pronounced capillary suction (sorption) occurred for the dry concrete specimens.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.677-680
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• 1999

Rapid developing automation technology enhances the need of sensors. Among many materials, silicon has the advantages of electrical and mechanical property, Single-crystalline silicon has different piezoresistivity on 야fferent directions and a current leakage at elevated temperature, but poly-crystalline silicon has the possibility of controling resistivity using dopping ions, and operation at high temperature, which is grown on insulating layers. Each wafer has slightly different thicknesses that make difficult to obtain the precisely same thickness of a diaphragm. This paper deals with the fabrication process to make poly-crystalline silicon based pressure sensors which includes diaphragm thickness and wet-etching techniques for each layer. Diaphragms of the same thickness can be fabricated consisting of deposited layers by silicon bulk etching. HF etches silicon nitride, HNO$_3$+HF does poly -crystalline silicon at room temperature very fast. Whereas ethylenediamice based etchant is used to etch silicon at 11$0^{\circ}C$ slowly.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.862-867
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• 2013

Since the industrial revolution, seawater has increased in temperature and acidity due to the increase in anthropogenic carbon dioxide in the atmosphere. To understand the effect of elevated $CO_2$ on the early life stages of fish, we reared fertilized eggs of black sea bream Acanthopagrus schlegelii under three $CO_2$ concentrations (400, 850 and 1550 ppm) for 3 weeks. The standard length and wet weight of black sea bream larvae declined with enhanced $CO_2$ concentration in the rearing water (P<0.05). However, chemical analysis using ICP-OES on internal tissues of black sea bream larvae indicated that the whole-body calcium concentration increased with $CO_2$ concentration in the rearing water. These conflicting results suggest that future experiments should examine the acid-base balance to investigate the formation of bone and otolith during larval growth.

• Journal of the Korean Ceramic Society
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• v.21 no.3
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• pp.278-282
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• 1984

Barium titanate powder was made by firing the complex hydroxide which had been synthesized with chemical wet process by the medium of $H_2O_2$. This experiment was done as following A mixed solution of $BaCl_2$, $TiCl_4$ and $H_2O_2$ with 1:1:10 mol ratio was prepared. Ammonium hydroxide was added into the mixed solution. In the range of pH 8-10 $BaTiO_3$ complex hydroxide was obtained and treated at room temperature 11$0^{\circ}C$, 20$0^{\circ}C$, 40$0^{\circ}C$ and $600^{\circ}C$. The results obtaiined from this experiment were as follows. At room temperature $BaTiO_3$ complex hydroxide was amorphous. Above 10$0^{\circ}C$ crystalline $BaTiO_3$ was obtained and particle size of $BaTiO_3$ was increased with elevated temperature. So the particle size of BaTiO3 could be controlled by the firing temperature. After treating $BaTiO_3$ complex hydroxide at 10$0^{\circ}C$ the average particle size of $BaTiO_3$ was 0.22$\mu\textrm{m}$.

• Applied Biological Chemistry
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• v.24 no.1
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• pp.29-39
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• 1981

Cooked spaghetti soaked in 10%, 20%, and 40% aqueous glycerine solutions for ten minutes absorbed sufficient glycerine to plasticize that spaghetti during and after subsequent drying. The plasticizing action of the glycerine prevented fissuring(checking) and surface corrugation of the spaghetti at elevated drying temperature and large wet-bulb dry-bulb temperature difference. The drying temperature and the wet-bulb dry-bulb differences up to which such protection was provided as the glycerine soak concentration increased. Despite the reduction in drying rate, the drying time required to produce spaghetti with a water activity of 0.65 (the level normally required for stability) decreased as glycerine content increased. At high frying temperatures glycerine addition increased the extent of browning and shortened the period required to induce detectale browning, but in all instances browning started well after the product $a_w$ reached the 0.65 value required for the completion of drying. Because glycerine addition reduced drying times at any given set of drying conditions and permitted the use of higher drying temperatures, relatively low levels of glycerine addition (e.g. 0.15 kg glycerine/kg dry spagetti) can shorten spagnetti drying times by roughly 80% and perhaps by as much as 93%.

• Journal of Powder Materials
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• v.20 no.1
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• pp.1-6
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• 2013

The key concept of nanopowder agglomerate sintering (NAS) is to enhance material transport by controlling the powder interface volume of nanopowder agglomerates. Using this concept, we developed a new approach to full density processing for the fabrication of pure iron nanomaterial using Fe nanopowder agglomerates from oxide powders. Full density processing of pure iron nanopowders was introduced in which the powder interface volume is manipulated in order to control the densification process and its corresponding microstructures. The full density sintering behavior of Fe nanopowders optimally size-controlled by wet-milling treatment was discussed in terms of densification process and microstructures.

• Journal of the Korean Burn Society
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• v.21 no.1
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• pp.17-21
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• 2018

Purpose: This study aimed to evaluate the thermal protective function of firefighter clothes and gloves through real scale fire simulations. Methods: Firstly, the fire simulation by real scale flame was performed for firefighter clothes. A manikin equipped with firefighter clothes was directly exposed to flames which energy average is 84 Kw/m². for 22 seconds. Heat flux gauges attached on the body measured surface temperature elevation. Secondly, we also performed the other fire simulation by hot plate exposure to firefighter gloves. Firefighter gloves with heat flux gauges exposed hot plate which temperature is 300℃ in both dry and moist conditions. Primary outcome was surface temperature change of manikin body (first simulation) and hand (second simulation) over times. Results: In the first flame simulation, the surface temperature of face and shoulders elevated more rapidly comparing with the other body surface area when initial period of flame shutter open. After 18sec of shutter open, the surface temperature of upper trunk elevated rapildy. After shutter closure, high surface temperature kept continuously on right side of face and left shoulder. In the second hot plate simulation, fingers and palms showed higher surface temperature than the other areas of hands in the both dry and wet conditions. Conclusion: This study suggests that the real scale flame enables firefighter clothes to lose their heat protective function suddenly after 18 seconds. Additionally, the protective function of firefighter gloves were relatively weaker in the palmar side of fingers than the other parts of hand. There should be additional study for evaluate thermal protection performance of firefighter clothes. And, further effort for reinforce palmar side of fingers of firefighter gloves should be done.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.103-114
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• 1995

Since autoheated thermophilic aerobic digestion (ATAD) process has various advantages for the treatment of high-strength organic wastewater, active research and field application has been applied in U.S.A. and Canada, recently and the interest in ATAD process has been elevated for treating high-strength organic wastewater efficiently in Korea. Therefore, various experiments were carried out to evaluate the feasibility of ATAD process for the treatment of pig manure wastewater. The results of this study showed possibility to reuse pig manure wastewater as wet fodder or liquid compost, since ATAD process led excellent stabilization on the basis of odor and putrefaction. However. digested sludge can not be provided as wet fodder to most of hog farms without changing dry feeder system into wet system and as liquid compost to hog farms not having their own grass land. Since the results showed that the increase of temperature in reactor was resulted not from energy by biological activity. but from mechanical mixing energy. the reactor investigated in this study was against the principle of ATAD process. Therefore. if pig manure wastewater treated by ATAD can not be utilized as wet fodder. it is not economical to adopt ATAD process only for the treatment of wastewater.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.119-128
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• 2010

The hygrothermal effect on the strength of composite single-lap bonded joints were investigated. The specimens were manufactured in four different manufacturing methods and tested in three different environmental conditions. An interesting result is that the strengths of the joints in the elevated temperature and wet (ETW) conditions were found to be 11 ~ 23% higher than those in the room temperature and dry (RTD) environment. In contrast, the strengths of the joints in the cold temperature and dry (CTD) condition decrease by 8 ~ 21% compared to those in the RTD environment except for cobonded joint. The difference in the strength by testing environments is mainly attributed to the change of the material properties of adhesive by temperature and moisture.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.759-764
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• 2017

This research investigated the hygrothermal effect on the strength of bolt jointed section and moisture contents of composites exposed to hygrothermal environment for composite aircraft radome. The decrease in strength in the test environment is mainly attributed to the change in the material properties of the matrix due to temperature and moisture. The composite specimens were tested in three different environmental conditions: RTD(room temperature and dry), CTD(cold temperature and dry) and ETW(elevated temperature and wet). The failure mode of the bolt jointed composite specimens were studied using tests and finite element analysis. Finite element analysis reasonably predicted the failure load and mode of the joints. A reliability-based design was carried out for the bolt jointed composites of radome.