• Journal of Korean Ophthalmic Optics Society
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• v.21 no.2
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• pp.119-126
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• 2016

Purpose: To analyze the effect of accommodative control and change values between subjective refraction (SR) and auto-refraction (AR) according to application of fogging after accommodative stimulation depending on ametropia type. Methods: Myopic ametropia 76 eyes and hyperopic ametropia 52 eyes participated for this study. SR and AR values measured by three test conditions (Before accommodative stimulation; Before AS, After accommodative stimulation; After AS, and After application of fogging; After AF) were compared, respectively. Results: In myopic eyes, (-)spherical power by SR and AR in After AS test was significantly increased as compared to Before AS test, (-)spherical power in After AF test was decreased to the level of Before AS test. The differences of spherical power between SR and AR were highly measured by SR in After AS test, and highly measured by AR in After AF test, respectively. In hyperopic eyes, (+)spherical power of SR significantly decreased in After AS test compared to Before AS test, more (+)spherical power was detected in After AF test compared to Before AS test. (+)spherical power of AR have no significant difference between Before AS and After AS test, but more (+)spherical power was detected in After AF test compared to Before AS test. The differences of (+)spherical power between SR and AR were significant in all test conditions. Among 52 eyes which were measured as hyperopic ametropia, 7 eyes were measured as myopia by SR in After AS test. In case of AR, 25 eyes among 52 eyes were mismeasured as myopia of ranges from -0.25 D to -1.25 D in Before AS test, 26 eyes in After AS test, and 19 eyes in After AF test were mismeasured as myopia of ranges from -0.25 D to -1.25 D. Conclusions: Regardless of ametropia type, accommodative control by After AF test was effective on both refraction process. However, in auto-refraction for hyperopic eyes, the misdetermined proportion of refractive error's type was high due to consistent accommodative intervention in all test condition. Therefore, in order to obtain an accurate value of refractive errors, full correction should be determined by subjective refraction process after fogging method.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.147-152
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• 2015

In order to develop the cooling load estimation method in the greenhouse, the cooling load calculation formula based on the heat balance method was constructed and verified by the actual cooling load measured in the fog cooling greenhouse. To examine the ventilation heat transfer in the cooling load calculation formula, we measured ventilation rates in the experimental greenhouse which a cooling system was not operated. The ventilation heat transfer by a heat balance method showed a relatively good agreement. Evaporation efficiencies of the two-fluid fogging system were a range of 0.3 to 0.94, average 0.67, and it showed that they increased as the ventilation rate increased. We measured thermal environments in a fog cooling greenhouse, and calculated cooling load by heat balance equation. Also we calculated evaporative cooling energy by measuring the sprayed amount in the fogging system. And by comparing those two results, we could verify that the calculated and the measured cooling load showed a relatively similar trend. When the cooling load was low, the measured value was slightly larger than calculated, when the cooling load was high, it has been found to be smaller than calculated. In designing the greenhouse cooling system, the capacity of cooling equipment is determined by the maximum cooling load. We have to consider the safety factor when installed capacity is estimated, so a cooling load calculation method presented in this study could be applied to the greenhouse environmental design.

• Food Science and Preservation
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• v.13 no.1
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• pp.1-7
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• 2006

The effects of packaging material and method on quality of fresh-cut mushrooms (Agaricus bisporus Sing.) were investigated in terms of weight loss, surface color, phenolics, vitamin C and sensory characteristics during storage at $5^{\circ}C$. The fresh-cut mushrooms were subjected to passive, gas exchange and vacuum packaging conditions at st. Polyethylene film (PE), polypropylene film (PP), anti-fogging film (AP) and pen orated film (PF) were used for the passive packaging. The mixed gas of $5\% CO_2/\;2\%O_2$ (MA1) and $10\%CO_2/\;2\%O_2$(MA2) were applied for the gas exchange packaging. The respiration rate of sliced mushroom was 1.27 times higher than intact mushroom at $5^{\circ}C$. Gas concentrations in the passive packaging were $1-2\%\;O^2\;and\;5-16\%m$ during storage of sliced mushrooms for 14 days at $5^{\circ}C$, and levels of the gases were different by the films used The mushroom in perforated film (PF) showed the highest weight loss of $4.56\%$. Anti-fogging film (AF) was somewhat effective for prevention of the weight loss compared with other films after 14 days storage. The mushrooms in MA1 and MA2 packages showed lower delta L value than in other films. PE packaging mitigated decrease of free and bound phenolics during storage. The mushrooms in MA2 kept better quality in sensory aspect, and then in MA1, PE and PP in order during storage at $5^{\circ}C$.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2004.03a
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• pp.220-223
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• 2004

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.735-740
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• 2002

In order to improve the anti-fogging property of polymer films, organic-inorganic hybrid coating solutions which have good hydrophilic property and transmission in the range of visible light were synthesized by the sol-gel method. The coating solutions were prepared by adding glycidoxypropyl trimethoxysilane(GPS) to a colloidal silica(15 nm) suspension(Ludox). GPS as silane coupling agent forms strong bonds to the colloidal silica and surrounding polymer matrix and links two different materials together. Solutions prepared by addition of GPS at the acidic condition resulted in coatings that were less prone to cracking, while those at the basic condition caused coatings with more cracking. These resulted in better hydrophilic property and transmission in the range of visible light for the solution prepared at the acidic condition(pH 2). Compared with coatings under acidic conditions, coatings prepared at basic conditions showed worse hydrophilic property and transmission in the range of visible light.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.1
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• pp.31-39
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• 2010

An exergy analysis is carried out for the regenerative gas turbine cycle which has a potential of enhanced thermal efficiency and specific power owing to the more possible water injection than that of inlet fogging under the ambient conditions. Using the analysis model in the view of the second law of thermodynamics, the effects of pressure ratio, water injection ratio and ambient temperature are investigated on the performance of the system such as exergetic efficiency, heat recovery ratio of recuperator, exergy destruction or loss ratios, and on the optimal conditions for maximum exergy efficiency. The results of computation for the typical cases show that the regenerative gas turbine system with afterfogging can make a notable enhancement of exergy efficiency.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.102-133
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• 2015

Nature, such as plants, insects, and marine animals, uses micro/nano-textured surfaces in their components (e.g., leaves, wings, eyes, legs, and skins) for multiple purposes, such as water-repellency, anti-adhesiveness, and self-cleanness. Such multifunctional surface properties are attributed to three-dimensional surface structures with modulated surface wettability. Especially, hydrophobic surface structures create a composite interface with liquid by retaining air between the structures, minimizing the contact area with liquid. Such non-wetting surface property, so-called superhydrophobicity, can offer numerous application potentials, such as hydrodynamic drag reduction, anti-biofouling, anti-corrosion, anti-fogging, anti-frosting, and anti-icing. Over the last couple of decades, we have witnessed a significant advancement in the understanding of surface superhydrophobicity as well as the design, fabrication, and applications of superhydrophobic coatings/surfaces/materials. In this talk, the designs, fabrications, and applications of superhydrophobic surfaces for multifunctionalities will be presented, including hydrodynamic friction reduction, anti-biofouling, anti-corrosion, and anti-icing.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.4
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• pp.141-148
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• 2009

Afterfogging of the regenerative gas turbine system has an advantage over inlet fogging in that the high outlet temperature of air compressor makes the injection of more water and the recuperation of more exhaust heat possible. This study investigates the effects of turbine inlet temperature (TIT) on the performance of regenerative gas turbine system with afterfogging through a thermodynamic analysis model. For the standard ambient conditions and the water injection ratios up to 5%, the variation of system performance including the thermal efficiency is numerically analyzed with respect to the variations of TIT and pressure ratio. It is also analyzed how the maximum thermal efficiency, net specific work, and pressure ratio itself change with TIT at the peak points of thermal efficiency curve. All of these are found to increase almost linearly with the increases of both TIT and water injection ratio.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.299-304
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• 2012

In this work, we experimented with the two-fluid fogging system that eco-friendly prevents whiteflies in greenhouses in order to find the optimal concentration of oleic acid supplied through the system and to evaluate the control value of three consecutive treatments. The first experiment, which was to find the optimal concentration of oleic acid, used "Dotaerang Gold" tomatoes grown in stand-alone plastic greenhouse at Buyeo Tomato Experiment Station. We tested three levels of concentration of oleic acid, which were 0, 2000, and 4000 ppm. The second experiment, which was to evaluate the control value of three consecutive treatments of oleic acid, used "Rokusanmaru" tomatoes grown in Venlo type glasshouse at Gyeonggi-Do Agricultural Research & Extension Services. In this experiment, oleic acid of 2000 ppm was applied three times with two days intervals. The number of whiteflies was counted 2 two days after the last application of oleic acid. Even when oleic acid was not being applied, the two-fluid fogging system was run from 9:00 am to 5:00 pm whenever the temperature is higher than $25^{\circ}C$ or the humidity is lower than 75%. In the first experiment, the control value was 81.6% with 2000 ppm of oleic acid and 93.6% with 4000 ppm. It means that the higher the concentration is, the greater the control value. In the second experiment, 2000 ppm treatment resulted in 85.8% of the control value, which is higher than the required standard for insecticides. Hence, spraying oleic acid with the concentration of 2000 ppm three times with two days intervals turned out to be a very effective in the eco-friendly prevention of whitefly.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.933-938
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• 2005

To investigate pertinent packaging treatment of fresh-cut potatoes (Solanum tuberosum L.), potato cubes were subjected to passive, gas exchange, and vacuum packaging conditions. Low density polyethylene film (LDPE), polypropylene film (PP), anti-fogging film (AP), and perforated film (PF) were used as passive packaging treatments. Mixed gases of 5% $CO_2/5%\;O_2$ (MA1) and 10% $CO_2/5%\;O_2$ (MA2) were applied as gas exchange packaging. Packs filled with cubes were kept at $5^{\circ}C$, and changes in weight loss, surface color, vitamin C content and sensory quality of cubes were analyzed during storage. Respiration rate of cubes was 2.11 times higher than that of intact raw potatoes at $5^{\circ}C$. Gas concentrations in passive packaging was maintained at 1-2% $O_2$ and 4-14% $CO_2$ after 7 days. Gas levels changed depending on films used. Cubes packed in PP and MA2 showed lowest weight loss and browning during storage. Firmness of cubes was not affected by packaging treatment. Vitamin C content was highest in cubes packed with AF. Cubes packed in MA2 showed highest quality upto 10days storage, followed by those packed in PP and AF.