• Korean Journal of Food Science and Technology
• /
• 제12권2호
• /
• pp.122-125
• /
• 1980

The mechanism of cooking barlay (naked and covered barley) was investigated. Cooking properties of both naked and covered barley were similar. At higher cooking temperature of above $110^{\circ}C$, a browning reaction occurred and no terminal point of cooking was observed. The cooking rate followed the equation of a first-order reaction. The activation energies of cooking temperatures below $100^{\circ}C$ and above $100^{\circ}C$ were about 19,500 and 9,500 cal/mole, respectively. The cooking process of barley comprised two mechanisms: At temperatures below $100^{\circ}C$ the cooking rate is controlled by the reaction rate of barley constituents with water, and at temperatures above $100^{\circ}C$, it is controlled by the rate of diffusion of water through the cooked portion toward the interface of uncooked core in which the reaction is occurring.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
• /
• pp.122-125
• /
• 2001

The objective of this research is to develop hybridized yarns for thermoplastic composites, and to examine tile effect of cooling rate on mechanical properties of the composites. The co-braided yarn utilizing carbon fibers as reinforcements and Nylon 66 fibers as matrix materials has been fabricated. Thermoplastic composites have been manufactured by the hot-press forming process. For the processing conditions, cooling rates of $-2.5^{\circ}C$/min and $-60^{\circ}C$/min have been considered. Three-point bending test and losipescu shear test were performed to investigate the effect of the cooling rate and the surface treatment of carbon fibers. SEM photographs were used to investigate the fracture surfaces of the tested samples. The cooling rate of $-60^{\circ}C$/min resulted in the higher strength and elastic modulus for bending and shear tests. The composites of the epoxy-sized carbon fibers showed the lowest strength due to the degradation of the sizing material during the thermoforming process.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
• /
• pp.172-177
• /
• 2005

The object of this experiment is comparing heat transfer performance and pressure drop characteristics by baffle cut rate, fluid velocity and heating temperature. Experiments were carried out in cross flow heat exchanger with water as a working fluid. In this experiment, baffle cut rate is 30%, 40%, 50%, velocity is 0.5m/s, 1.0m/s, 1.5m/s, and heating temperature is $30^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$. An experimental device to measure the heat transfer coefficient was constructed. The experimental result were obtained for the fully developed turbulent flow of water in tube on the condition of uniform heat flux.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• 제11권2호
• /
• pp.244-249
• /
• 1999

This study is to examine the emission rate of $CO_2$gas as the environmental load in office buildings. After the investigation of monthly consumption of each energy source(electricity and natural gas), it is analyzed that the $CO_2$emission rate of 34 office buildings surveyed is 22.4kg-$c/m^2$.year, which consists of 17.5kg-$c/m^2$.year by consuming electricity, and 4.9kg-$c/m^2$.year by consuming natural gas. And the $CO_2$emission rate of each load in those buildings consists of 68% emitted by general electricity, 16% by cooling load and 16% by heating load. It is also proposed that the $CO_2$emission rate of cooling and heating load is profoundly pertinent to the variation of outdoor temperature.

• Transactions of Materials Processing
• /
• 제10권1호
• /
• pp.35-41
• /
• 2001

The high temperature deformation behavior of SCM 440 can be characterized by the hot torsion test in the temperature ranges of $900^{\circ}C$~$1100^{\circ}C$ and strain rate ranges of 0.05/sec~5/sec. The aim of this paper is to establish the quantitative equation of the volume fraction of dynamic recrystallization (DRX) as a function of processing variables, such as strain rate ($\varepsilon$), temperature (T), and strain ('$\varepsilon$). During hot deformation, the evolution of microstructure could be analyzed from work hardening rate ($\theta$). For the exact prediction of dynamic softening mechanism the critical strain ($\varepsilon_c$), the strain for maximum softening rate ($\varepsilon^*$ and Avrami' exponent (m') were quantitatively expressed by dimensionless parameter, Z/A, respectively. The transformation-effective strain-temperature curve for DRX could be composed. It was found that the calculated results were agreed with the experimental data for the steel at any deformation conditions.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제11권1호
• /
• pp.165-177
• /
• 2019

This paper considers corrosion wastage of two ship hull structure members as a part of investigated fuel oil tanks of 25 aging bulk carriers. Taking into account that many factors which influence corrosion wastage of ship hull structures are of uncertain nature, the related corrosion rate ($c_1$) is considered here as a real-valued continuous distribution, assuming that the corrosion wastage starts after 5, 6 or 7 years. In all considered cases, by using available data and applying three basic statistical tests, it is established that between two-parameter continuous distributions, normal, Weibull and logistic distributions are best fitted distributions for the mentioned corrosion rate ($c_1$). Note that the presented statistical, numerical and graphical results concerning two mentioned ship hull structure members allow to compare and discuss the corresponding probabilistic estimates for the corrosion rate ($c_1$).

• Journal of the Korean Ceramic Society
• /
• 제27권4호
• /
• pp.560-566
• /
• 1990

The early hydration characteristics according to the C3A polymorphism and the presence of gypsum, in order to establish the hydration mechanism of the system C3S-C3A, have been studied. The hydration rate of C3A was changed according to the its crystal structure and influenced the hydration of C3S. That is, the hydration rate of C3S was accelerated in case of orthorhombic-C3A, but that was slightly retarded in case of melt-C3A than that of cubic-C3A. In the system C3S-C3A-gypsum, the retardation phenomenon of the reaction of monosulfate formation was observed in case of both orthorhombic and melt-C3A.

• Journal of the Korean Society for Heat Treatment
• /
• 제8권4호
• /
• pp.289-301
• /
• 1995

The effect of Air/$C_3H_8$ gas addition on the compound layer growth of steels nitrocarburised in $NH_3+Air+C_3H_8$ mixed gas atmospheres was investigated. It is considered that amount of residual $NH_3$ was varied according to alternation of Air/$C_3H_8$ mixing ratio and volume content. The compound layer formed from nitrocarburising was composed of ${\varepsilon}-Fe_{2-3}$(C, N) and ${\gamma}^{\prime}-Fe_4$(C, N). According as Air/$C_3H_8$ mixing ratio increased, the superficial content of ${\gamma}^{\prime}-Fe_4$(C, N) within the compound layer was increased, at the same time the growth rate of compound layer and porous layer was increased. In the case of alloy steel at the fixed gas composition, the growth rate of compound layer and porous layer was worse than carbon steel and compound layer phase composition structure primarily consisted of E phase. As the carbon content of materials was increasing in the given gas atmospheres, the growth rate of compound layer and porous layer was increased and the superficial content of ${\varepsilon}-Fe_{2-3}$(C, N) within the compound layer was increased.

• Journal of Aquaculture
• /
• 제17권1호
• /
• pp.58-61
• /
• 2004

Larvae of Pandalus gracilis were reared in the laboratory under controlled conditions (salinity, 32.5∼34.5; photo-periods, 12L: 12D). The experiments were designed to examine effects of temperature (10 and 2$0^{\circ}C$) on larval development, survival, intermolt period and larval growth. The higher survival rate was obtained at 2$0^{\circ}C$ than at 1$0^{\circ}C$ and larvae reached later stages at 2$0^{\circ}C$. Intermolt period increased significantly with increasing of instar number and was longer at 1$0^{\circ}C$ than at 2$0^{\circ}C$.

• Journal of Power System Engineering
• /
• 제21권2호
• /
• pp.20-26
• /
• 2017

This study was carried out to investigate the effect of precipitate on the high temperature deformation stability of incoloy 825 alloy. $Cr_{23}C_6$ carbide was precipitated under $950^{\circ}C$, but was not detected over $1,000^{\circ}C$. Most of the precipitation consist of $Cr_{23}C_6$ carbide. Strain-rate sensitivity was the highest in 0.01/s and the lowest in 10/s. Strain-rate sensitivity was decreased sharply below $950^{\circ}C$. In the temperature between $850^{\circ}C{\sim}1,150^{\circ}C$, plastic instable area did not exist. It showed the lowest Ziegler Parameter value of 0.06 Ziegler Parameter was the lowest as 0.06 at $850^{\circ}C$ with 10s-1 of strain. The highest Ziegler Parameter value(0.43) was found in plastic deformation at $1,050^{\circ}C$ with 0.01s-1 of strain. It tends to have an higher resistance to the high temperature deformation under $950^{\circ}C$, due to the precipitation.