• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.36-46
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• 2001

Finite element analyses of the ceramic drying process are performed. The heat and moisture movements in green ceramics caused by temperature gradient, moisture gradient, conduction, convection and evaporation are considered. The finite element formulation for solving the temperature and moisture distributions which not only change the volume but also induce the hygro-thermal stress is carried out. In order to verify the formulation, the drying process of a ceramic electric insulator is simulated. Temperature distribution, moisture distribution, and hygro-thermal stress are compared with those of other researcher. Good agreements are achieved.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.457-462
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• 2003

It studies the non-structural crack factors that are produced in Steel Box Girder Bridge concrete floor plate using analytical method. It mainly studies humidity and design standard of concrete strength. It used MIDAS CIVIL Ver 5.4.0, a general structure analysis program that applies drying shrinkage rate of domestic road bridge design standard and standard value of creep coefficient, CEF-FIP standard equation and ACI standard equation from the aspect of creep, drying shrinkage and hydration heat to see the effect of the two factors on concrete crack and found the following result. The analytical results of this study showed that the initial stress, which was obtained by ACI standard, exceeds the allowable tensile stress between 5 to 18 days. This result means that even if a bridge is designed and constructed according to design standard, the bridge can have cracks due to various variables such as drying shrinkage, hydration heat and creep that produce stress in slab.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.3
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• pp.508-519
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• 2008

Hot air drying is a method that let moistures evaporate by heat exchange between heating air and dry target. This way is dominating more than about 70% of dryers that the use extent is wide fairly, and is established in domestic than dryer that use conduction or radiation etc. Most of research about drying had been emphasized in size of device through analysis for these dry phenomenon plain, heating topology, and aspect of form and so on by dry target's special quality, and research about device development or waste heat withdrawal technology in energy utilization efficiency side is slight real condition. Therefore, in this study, Investigated numerically about thermal efficiency elevation that is leaned against as that change the temperature of inlet and outlet in heat exchanger of the hot air drying tower.

• Journal of Biosystems Engineering
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• v.15 no.3
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• pp.230-243
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• 1990

This study was conducted to investigate the possibility of application of an infrared drying to drying process for red pepper. The performance of seramic heaters and the variation of temperature and moisture content of red pepper were analyzed during an infrared drying of red peppers. Also, the quality of dried red pepper was analyzed. The following results were obtained from this study. 1. The surface temperature of infrared heaters and the rising time required for steady state were mainly affected by electrical power consumed. 2. The heat energy required for heating red pepper was proposed to be calculated by the equation in terms of enthalpy of air and net heat flux by infrared heater in a drying chamber. The statistical model for net heat flux was developed. 3. The performance of the infrared heater used for heating red pepper was much affected by the distance of radiation, and the difference of temperatures appeared between the radiated surface and the inside of red pepper. 4. Electrical capacity of the infrared heater had a significant effect on the heating of red pepper. However, the effect of shape of heater on heating was not significant. 5. The variation of temperature of red pepper largely appeared in the range of 30 to 60% (db) in moisture content. The temperature of red pepper was almost constant at low moisture content. 6. The temperature of red pepper and heating time had significant effects on the quality for radiant heating. 7. When the electrical capacity of infrared heater and the distance of radiation are carefully designed in a dryer with the insulated drying chamber, infrared drying might be very effective in red pepper drying.

• The Journal of Natural Sciences
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• v.14 no.1
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• pp.139-149
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• 2004

It was aimed to find out an efficient method of drying hot pepper, of which powder is used as one of the main ingredients in Korean dish preparation including Kimchi. Before sun or heat drying fruits harvested were horizontally cut into three pieces punched with an auger of 4 mm in diameter, or used as the whole fruit. Various drying methods were used including sun drying, drying under a plastic house, sun drying after heat drying for 5 hours at $70^{\circ}C$, $80^{\circ}C$, or $90^{\circ}C$, heat drying only at $50^{\circ}C$, $60^{\circ}C$, or $70^{\circ}C$, and changing temperature of $70^{\circ}C$, $5hours+60^{\circ}C$ until coplete dry, $80^{\circ}C+60^{\circ}C$, or $90^{\circ}C+60^{\circ}C$. The results are summarized as follows. With sun drying of the whole fruit, in required about 10days to reach the satisfactory level of dryness as indicated by its moisture content of below 10% in general. In case of heat drying combined with sun drying, it required 5 to 7 days. For cut fruits, it required 1 or 2 days less than for whole or pinholed fruits until drying. Under heat of alternation temperature drying, cut fruits also dried 15-20 hours earlier compared with whole of pinholed fruits. There were not significant differences for the recovery rate of the fruit with various drying methods. The occurrence of white fruits, which are caused by one of physiological disorders during drying, and rotten fruits was reduced with the cut fruit drying. The damages were very high with the PE house drying, but very little with the heat drying.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.413-422
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• 2000

Samples of banana were dried in a two-stage heat pump dryer capable of producing stepwise control of the inlet drying air temperature while keeping absolute humidity constant. Two stepwise air temperature profiles were tested. The incremental temperature step change in temperature of the drying air about the mean air temperature of 30 $^{\circ}C$ was 5 $^{\circ}C$. The total drying time for each temperature-time profile was about 300 minutes. The drying kinetics and color change of the products dried under these stepwise variation of the inlet air temperature were measured and compared with constant air temperature drying. The stepwise air temperature variation was found to yield better quality product in terms of color of the dried product. Further, it was found that by employing a step-down temperature profile, it was possible to reduce the drying time to reach the desired moisture content.

• Journal of computational fluids engineering
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• v.20 no.3
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• pp.70-78
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• 2015

Turbulent flow and heat transfer characteristics of textile machine are numerically investigated. To examine the influence of flow structures on the drying performance of fabrics, the nozzle shape of high temperature chamber is changed. For several nozzles, flow and heat transfer characteristics are discussed. The results show that the drying performance is improved by controlling the angle and arrangement of nozzles corresponding to different drying conditions. This feature is strongly related to the enhancement of turbulent fluctuations and secondary flows.

• Solar Energy
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• v.17 no.2
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• pp.3-11
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• 1997

In conventional heat and vent dryer, both sensible and latent heat could not be recovered from the exhaust air, but this problem could be solved by introducing a heat pump to a conventional dryer, having a connection with cooling, dehumidifying and heating of heat pump. In this work, HFC134a as a substitute refrigerant of CFC12 adopted in heat pump and a batch type is also introduced. The variables affected on the system performance are holding temperature of a drying chamber, bypass air ratio, degree of superheat and refrigerant flowrate, etc. The moisture contents were decreased curvilinearly in the range of $86{\sim}75%$ on the wet basis. Under the constant drying temperature, the face velocity plays an important role to the drying performance. The COPs are increased in accordance with the air velocity, on the other hand the SMERs are gradually decreased.

• Fashion & Textile Research Journal
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• v.11 no.6
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• pp.961-967
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• 2009

In order to examine the availability of heat treatment for color developing in persimmon dyeing, the rayon fabrics dyed with persimmon extract from unripe persimmon which was used after stock and fermentation. Dyed fabrics were heated at various temperature and time by contacting press heat and drying heat. Color developing results were influenced by the difference of heating method. Press heating method is more available than drying heat method. Effect of temperature and time on ${\Delta}Ea^*b^*$ and color values of dyed rayon fabrics was considerable. Considering the practical aspect, The temperature around $140{\sim}160^{\circ}C$ and the time no longer 40 minutes can be reach the region of the full color developing by press heating process. It was very shortened than any other method(drying air heat, xenon radiation, sunlight). The dyed rayon fabrics with heat treatment have darker and deeper red-yellow color than which by sunlight and xenon radiation.

• Journal of the Korean Wood Science and Technology
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• v.47 no.5
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• pp.567-578
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• 2019

A common problem with fast-growing hardwoods is dimensional instability that limits use of their wood. In this study, we investigated the effects of pre-drying methods, temperatures, and heating duration on the specific gravity, water absorption, and dimensional stability of three tropical fast-growing hardwoods, jabon (Neolamarckia cadamba Roxb.), sengon (Falcataria moluccana Miq.), and mangium (Acacia mangium Willd.). Wood samples were pre-dried by two methods (fan and oven at $40^{\circ}C$), and heat treatments were performed at three temperatures (120, 150, and $180^{\circ}C$) for two different time periods (2 and 6 hours). The specific gravity, water absorption, dimensional stability, and structural changes of the samples were evaluated. The results revealed that heat treatments slightly reduced the specific gravity of all three wood species. In addition, the heat treatments reduced water absorption and significantly improved dimensional stability of the samples. Oven pre-drying followed by heat treatment at $180^{\circ}C$ for 6 hours resulted in good physical improvement of jabon and sengon wood. Fan pre-drying followed by heat treatment at $180^{\circ}C$ for 2 hours improved the physical properties of mangium wood. The heat treatment shows a promising technique for improving the physical characteristic of fast growing hardwoods.