• Transactions of Materials Processing
• /
• v.13 no.1
• /
• pp.45-52
• /
• 2004

This research conducted milling tests to study effects of cutting environment conditions of ball end mills on the characteristics of hard milling process. KP4 steels and STD11 heat treated steels were used as the workpiece and WC-Co ball end mill tools with TiAlN coated were utilized in the cutting tests. Dry cutting without coolant and semi-dry cutting using botanical oil coolant were conducted and MQL(Minimum Quantity Lubricant) device was used to spray coolant. Cutting forces, tool wear and surface roughness were measured in the cutting tests. Results showed that dry cutting of KP4 and hardened STD11 specimens produced better surface quality and wear performance than MQL spray cutting did.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.149-150
• /
• 2018

Recently, a large fire has occurred through a dry bit, which is a flammable exterior material, in Daebong Green Apartment Fire in Uijeongbu in 2015 and Jecheon Sports Center Fire in 2017. In this study, KS F ISO 5660-1 Cone calorimeter experiment was used to examine the fire risk of dry bit. Also, the performance of the repair and reinforcement materials to prevent fire expansion was examined. As a result, the dry bit is likely to be ignited by internal and external flower gardens, and its combustion rate and calorific value are very high. In addition, the performance of heat resistance such as ALC panel and ceramic board as a repair and reinforcement material has been proved. However, the insulation is expected to require further consideration.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.4
• /
• pp.805-809
• /
• 1999

The growth of Lactobacillus casei in milk was enhanced by adding yams. Addition of 1% yam(raw or dry) promoted the cell growth and acid production in fermented milk. The milk containing 1% yams formed the complete curd by lactic acid fermentation at 37oC for 19hr while the milk without yams showed the incomplete curd formation. The crude mucilage extracted from a raw yam also enhanced the cell growth as well as the acid production. Addition of mucilage(0.08%) showed the similar effects with adding heat treated yam(1%). The milk fermented by adding various yams showed the high scores for sensory evaluation comparing with the milk fermented without yams. The fermenting ability of Lactobacillus acidophilus, Lactobacillus kefir and Leuconostoc mesenteroides was evaluated by adding 1% of a dry yam in milk. A dry yam also enhanced the cell growth of L. acidophilus resulting in the high acid production. The viable cell counts of L. casei, L. acidophilus and Leuc. mesenteroides except L. kefir were increased by adding 1% of a dry yam.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.16 no.1
• /
• pp.9-14
• /
• 2008

In this study, pressure drop and heat transfer characteristics of plain finned heat exchangers having 5.0 mm diameter (fin collar 5.3 mm) tubes were investigated. Six samples having different fin pitches (1.1 to 1.3 mm) and tube rows (1 and 2 row) were tested. The fin pitch had a negligible effect on j and f factors. Both j and f factors decreased as the number of tube row increased, although the difference was not significant for the f factor. When compared with the j and f factors of the samples having 7.3 mm diameter tubes, the present j and f factors yielded lower values. However, the j/f ratio was larger at low Reynolds numbers. Possible reasoning is provided from the flow pattern consideration. Comparison with existing correlations were made.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.390-391
• /
• 2005

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2004.04a
• /
• pp.272-273
• /
• 2004

• Journal of computational fluids engineering
• /
• v.21 no.2
• /
• pp.47-53
• /
• 2016

This study investigated natural convection flow behavior in airflow path designed in concrete dry storage cask to remove the decay heat from spent nuclear fuels. Using FLUENT 16.1 code, thermal analysis for natural convection was carried out for three dimensional, 1/4 symmetry model under the normal condition that inlet ducts are 100% open. The maximum temperatures on other components except the fuel regions were satisfied with allowable values suggested in nuclear regulation-1536. From velocity and temperature distributions along the flow direction, the flow behavior in horizontal duct of air inlet and outlet duct, annular flow-path and bent pipe was delineated in detail. Theses results will be used as the theoretical background for the composing of airflow path for the designing of passive heat removal system by understanding the flow phenomena in airflow path.

• Journal of the Korean Society for Heat Treatment
• /
• v.11 no.3
• /
• pp.186-191
• /
• 1998

An oxidation behavior of 304 and 316 stainless steels were studied in dry air. After solution treatment, specimens were polished up to $1{\mu}m$ $A1_2O_3$ grade and then subjected to oxidation treatment in dry air at $800^{\circ}C{\sim}1200^{\circ}C$. The oxidation behavior between matrix and oxide scale was analyzed with SEM, EDS and XRD. When oxidation treatment was conducted at $1200^{\circ}C$, large thickness of Fe oxide scale was formed on top of surface and fine $(Cr,Fe)_2O_3$ oxide film was formed below it. Cr rich zone existed at interface between metal and $(Cr,Fe)_2O_3$ oxide layer, and it was believed that this zone acted as obstacle to oxidation. Most of Ni was detected at the interface between metal and $(Cr,Fe)_2O_3$ and also detected at the interface between $Fe_2O_3$ and $(Cr,Fe)_2O_3$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.10
• /
• pp.891-897
• /
• 2005

The characteristics of energy Performance for total heat exchanger have been investigated under various conditions. In cooling operation the latent and enthalpy efficiency are affected by the difference of absolute humidity ratio between indoor and outdoor air. In addition to this the characteristics of absorbing material in the element affects the energy performance. Low dry bulb temperature of indoor air or high absolute humidity ratio in outdoor air give high latent and enthalpy efficiency even with the same temperature difference of dry bulb temperate between indoor and outdoor air.

• Nuclear Engineering and Technology
• /
• v.53 no.10
• /
• pp.3359-3366
• /
• 2021

An engineered barrier system (EBS) for the deep geological disposal of high-level radioactive waste (HLW) is composed of a disposal canister, buffer material, gap-filling material, and backfill material. As the buffer fills the empty space between the disposal canisters and the near-field rock mass, heat energy from the canisters is released to the surrounding buffer material. It is vital that this heat energy is rapidly dissipated to the near-field rock mass, and thus the thermal conductivity of the buffer is a key parameter to consider when evaluating the safety of the overall disposal system. Therefore, to take into consideration the sizeable amount of heat being released from such canisters, this study investigated the thermal conductivity of Korean compacted bentonites and its variation within a temperature range of 25 ℃ to 80-90 ℃. As a result, thermal conductivity increased by 5-20% as the temperature increased. Furthermore, temperature had a greater effect under higher degrees of saturation and a lower impact under higher dry densities. This study also conducted a regression analysis with 147 sets of data to estimate the thermal conductivity of the compacted bentonite considering the initial dry density, water content, and variations in temperature. Furthermore, the Kriging method was adopted to establish an uncertainty metamodel of thermal conductivity to verify the regression model. The R² value of the regression model was 0.925, and the regression model and metamodel showed similar results.