• Journal of the East Asian Society of Dietary Life
• /
• v.25 no.5
• /
• pp.842-849
• /
• 2015

The purpose of this study was to determine the optimal mixing ratio of hot-air dried loquat leaf powder and optimum conditions for making Jeolpyun containing hot-air dried loquat leaf powder (LLP). Samples of Jeolpyun were prepared with different contents of hot-air dried LLP (0%, 3%, 6%, 9%, 12%) followed by analysis of chemical properties, moisture contents, color, mechanical quality characteristics, amylograph, and sensory tests. Chemical analysis showed that hot-air dried LLP consisted of 11.41% water, 8.34% crude protein, 1.90% crude fat, 7.74% crude ash, and 16.95% crude fiber, with $^{\circ}Brix$ of 2.07, and pH of 5.78. Moisture contents of samples ranged from 52.22 to 50.06%. L-value decreased with addition of hot-air dried LLP, whereas a-value increased with increasing amount of hot-air dried LLP, and no significant differences were observed regarding b-value. In the mechanical evaluation of physical properties, hardness deceased with increasing amount of hot-air dried LLP. The starting temperature amylograph of Jeolpyun was higher in samples with hot-air dried LLP than those without hot-air dried LLP. Set back was slower with increasing amount of hot-air dried LLP, an increasing amount of hot-air dried LLP made set back of Jeolpyun slower. In the sensory test, Jeolpyun with 6% hot-air dried LLP was the most preferred with less bitterness and proper softness, moisture and chewiness. Therefore, addition of 6% hot-air dried LLP to Jeolpyun made with rice flour showed the best overall preference. Based on the results of this experiment, samples with hot-air dried LLP showed slower hardening than those without hot-air dried LLP in textural changes during storage, and Jeolpyun with 6% hot-air dried LLP is expected to increase quality and preference of Jeolpyun.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.11 no.4
• /
• pp.22-27
• /
• 2015

Quality characteristics of Shiitake mushroom using two types of dryers, energy-efficient heat pump hot-air dryer and electric heater hot-air dryer were compared. Energy consumed during drying by heat pump hot-air dryer and electric heater hot-air dryer were 22.8 kWh and 28.9 kWh, respectively. Total polyphenol content of heat pump hot-air dryer and electric heater hot-air dryer after drying were $290.55{\pm}10.56ppm$ and $192.99{\pm}6.53ppm$, respectively. No differences were observed between dryers in reconstitution rate and browning ratio after drying. Also, there were no differences between dryers in color value and ${\Delta}E$ value after drying. Shiitake mushroom drying at $45^{\circ}C$ by heat pump hot-air dryer was proved to be more efficient in energy consumption than by electric heater hot-air dryer.

• Transactions of Materials Processing
• /
• v.24 no.1
• /
• pp.20-27
• /
• 2015

Hot tensile tests were conducted at different temperatures ranging from $20^{\circ}C$ to $550^{\circ}C$ to evaluate the mechanical properties of Al5052 seamless tubes. Such tubes can provide the technological foundation for complex forming using hot air bulging. Hot air bulging is one of the recently developed hydroforming techniques and it has some limitations in terms of cycle times. The benefits of hot air bulging are weight and cost savings through part consolidation and reduced post-forming processes such as welding and piercing. In order to extend the forming limits of Al lightweight material hot air bulging was investigated. A heated tube was placed in a heated die and sealed at the ends by sealing cylinders. The heated tube was subsequently expanded against the die cavity wall by internal pressure using air medium. The results of the current study show that axial feeding speed and air pressure have an effect on the formability of Al tubes during air bulging at elevated temperatures.

• Korean Journal of Food Science and Technology
• /
• v.35 no.2
• /
• pp.329-333
• /
• 2003

Fruits of 'Manita', a red pepper cultivar, and 'HL', a cultivar bred for single-harvest, cultivated by direct sowing method were harvested simultaneously. The red fruits were freeze-, sun-, indoor-, hot-air $(65^{\circ}C)$, and excessive hot-air (50% longer time) dried. For Manita. ASTA values of freeze- and indoor-dried red pepper were the highest $(153.6{\sim}168.4)$, and those of sun- and hot air-dried ones were $119.2{\sim}131.5$. Excessive hot-air drying decreased the redness by about $9{\sim}15%$ compared to normal hot-air drying. For HL, ASTA values $(150.3{\sim}171.7)$ of indoor-dried red peppers were much higher than other dried peppers. Red pigment in HL was destroyed easily during sun drying, showing values of only $49.2{\sim}69.2$. By excessive hot-air drying, the redness did not decrease, compared to normal hot-air drying. The organic acid contents of both cultivars were higher in sun- and hot-air-dried ones than freeze- and indoor-dried ones. Copsaicinoid contents of both cultivars decreased up to 22% by excessive hot-air drying compared to normal hot-air drying. Sugar contents were lower in all drying methods other than freeze drying for both cultivars.

• Journal of the Korean Institute of Rural Architecture
• /
• v.16 no.4
• /
• pp.75-81
• /
• 2014

In this study, we have intended to provide the related construction manuals with technical materials and to reduce the defects in the on-site construction, with reviewing the adhesive properties of joint parts according to change of temperature and speed of hot-air sealer for the products that have been made of polyvinyl chloride(PVC) materials in the single waterproof sheet. The result from the experiment is shown as following. 1) Bond strength was shown as high as the welding speed became slower. For the hot-air welding velocity with 3~6m/min, a stable bond strength has been shown in the range of the hot-air welding temperature with $175{\sim}210^{\circ}C$, while it has been shown in the range of the hot-air welding temperature with $210^{\circ}C$, when the hot-air welding velocity is between 9~12m/min. 2) If the hot-air welding temperature is lower, the adhesive strength has been shown as higher in the section where the hot-air welding velocity is low, while the adhesive strength has been also shown as higher in the section where the velocity is fast as the hot-air welding temperature becomes higher. The highest bond strength has been shown in the velocity with 3m/min for the hot-air welding temperature with $140{\pm}10^{\circ}C$, which is rather low. At $175{\pm}10^{\circ}C$, a high bond strength has been shown in the velocity with 3~6m/min, while the high bond strength has been shown in the velocity with 6~9m/min at $210{\pm}10^{\circ}C$.

• Journal of Korean Society on Water Environment
• /
• v.23 no.5
• /
• pp.665-675
• /
• 2007

In-situ Air Sparging (IAS, AS) is a remediation technique in which organic contaminants are volatilized from saturated zone to unsaturated layer. This study focuses on the removal and interaction of Volatile Organic Compounds (VOCs) and $CO_2$, and Total Petroleum Hydrocarbon (TPH) in saturated and unsaturated, and air space zone on the unsaturated soil surface. Soil sparging temperature of hot air has risen to $34.9{\pm}2.7^{\circ}C$ from $23.0{\pm}1.9^{\circ}C$ for 36 days. At the diffusing point, fluid TPH concentrations were reduced to 78.7% of the initial concentration in saturated zone when hot air was sparged. The TPH concentrations were decreased to 66.1% for room temperature air sparging. The amount of VOCs for hot air sparging system, in air space, was approximately 26% larger than constant air sparging system. The amount of $CO_2$ was 4,555 mg (in unsaturated zone) and 4,419 mg (in air space) when hot air was sparged was 3,015 mg (in unsaturated zone) and 3,634 mg (in air space) for room air temperature in the $CO_2$ amount. The removals of VOCs and biodegradable $CO_2$ through the hot air sparging system (modified SVE) were more effective than the room temperature air sparging. The regression equation were $Y=976.4e^{-0.015{\cdot}X}$, $R^2=0.98$ (hot air sparging) and $Y=1055e^{-0.028{\cdot}X}$, $R^2=0.90$ (room temperaure air sparging). Estimated remediation time was approximately 500 days, if final saturated soil TPH concentration was set to 1.2 mg/L application of tail effect.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.2_2
• /
• pp.271-278
• /
• 2022

The solar energy has been widely used to reduce the fossil fuel and prevent the environmental pollution. The renewable energy including solar heat tends to spread due to carbon neutrality for main country of the world. Targets of solar collector are usually acquisitions of hot water or hot air. Especially, air-heating collector using solar heat is known as the technology for obtaining hot air. This study aims to investigate of characteristics of thermal flow when the hot air by air-heating collector using solar heat flows inside of indoor space. The thermal flow of heating indoor space was simulated using ANSYS-CFX program and thus the behaviors of hot air in indoor space were evaluated with standard k-𝜀 turbulence model. As the results, as the inlet velocity was increased, the behaviors of hot air became simple, and temperature range of 25~75℃ had almost no effect on behavior of flow. As the inlet temperature was increased, the temperature curve of indoor space from bottom to top was changed from linear to quadratic. Furthermore, it was confirmed that inlet velocity as well as inlet temperature also should be considered to heat indoor space equally by air-heating collector using solar heat.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.4_2
• /
• pp.467-474
• /
• 2021

The renewable energy is known as eco-friendly energy to reduce the use of fossil fuel and decrease the environmental pollution due to exhaust gas. Targets of solar collector in domestic are usually acquisitions of hot water and hot air. System of air-heating collector is one of the technologies for obtaining hot air in cases of especially heating room and drying agricultural product. The purpose of this study is to investigate the characteristics of thermal flow such as relative pressure, velocity, outlet temperature and buoyancy effect in air-heating collector using solar heat. The flow field of air-heating collector was simulated using ANSYS-CFX program and the behaviour of hot air was evaluated with SST turbulence model. As the results, The streamline in air-heating collector showed several circular shapes in case of condition of buoyancy. Temperature difference in cross section of outlet of air-heating collector did not almost show in cases of buoyancy and small inlet velocity. Furthermore merit of air-heating collector was not observed in cases of inlet velocities. Even though it was useful to select condition of buoyancy for obtaining high temperature, however, it was confirmed that the trade off between high temperature of room and rapid injection of hot air to room could be needed through this numerical analysis.

• Journal of Biosystems Engineering
• /
• v.34 no.5
• /
• pp.363-370
• /
• 2009

Hot air heater with light oil combustion is used as the most common heater for greenhouse heating in the winter season. Hot air heaters of 256,246 units have been supplied as main greenhouse heating equipment until 2008 and greenhouse heating cost has reached to 620 billions won in Korea. In order to improve the thermal efficiency of the hot air heater and to reduce the expenses for greenhouse heating, prototype hot air heater was manufactured and tested in this experiment. The heat exchanger of tested prototype hot air heater was circular and hexagonal pipe type and inline and stagger arrangement type. Capacity of the heating was 43,062 kJ/h and total heat transfer area of the heat exchanger was $10.728\;m^2$. According to the performance test, it could supply heat of 38,240 to 35,100 kJ/h depending on the fan motor speed of 1,740~1,220 rpm, respectively. Thermal efficiency of hot air heater was 87.0% to 80.8% in the same conditions. As a result, thermal efficiency of hot air heater with hexagonal pipe-stagger arrangement heat exchanger developed in this study was higher 10.2% than that of conventional hot air heater and heating energy saving rate of 14.3% increased.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.61 no.4
• /
• pp.270-276
• /
• 2016

The objective of this study was to find a rapid determination of the hot air stress in maize (Zea mays L.) leaves using a portable chlorophyll fluorescence imaging instrument. To assess the photosynthetic activity of maize leaves, an imaging analysis of the photochemical responses of maize was performed with chlorophyll fluorescence camera. The observed chlorophyll imaging photos were numerically transformed to the photochemical parameters on the basis of chlorophyll a fluorescence. Chlorophyll a fluorescence imaging (CFI) method showed that a rapid decrease in maximum fluorescence intensity ($F_m$) of leaf occurred under hot air stress. Although no change was observed in the maximum quantum yield ($F_v/F_m$) of the hot air stressed maize leaves, the other photochemical parameters such as maximum fluorescence intensity ($F_m$) and Maximum fluorescence value ($F_p$) were relatively lowered after hot air stress. In hot air stressed maize leaves, an increase was observed in the nonphotoquenching (NPQ) and decrease in the effective quantum yield of photochemical energy conversion in photosystem II (${\Phi}PSII$). Thus, NPQ and ${\Phi}PSII$ were available to be determined non-destructively in maize leaves under hot air stress. Our results clearly indicated that the hot air could be a source of stress in maize leaves. Thus, the CFI analysis along with its related parameters can be used as a rapid indicating technique for the determining hot air stress in plants.