• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.428-436
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• 2012

This study aimed to develop the multi-span plastic greenhouse which is suitable for tomato cultivation and is safe against climatic disasters such as typhoon or heavy snow. The width and heights of eaves and ridge of newly developed tomato greenhouse are 7, 4.5 and 6.5 m, respectively. The width is the same but the eaves and ridge heights are 1.8 and 2 m higher than conventional 1-2 W greenhouses, respectively. Cross beam has been designed as a truss structure so it can sustain loads of tomato and equipment. Tomato greenhouse has been designed according to climatic disaster preventing design standard maintaining the high height. In other words, the material dimensions and interval of materials including column and rafter have been set to stand against $40m{\cdot}s^{-1}$ of wind and 40 cm of snow. Tomato greenhouse has been equipped with rack-pinion type roof vents which have been used in glass greenhouse in order to prevent excessive rise in air temperature. This vent type is different from that of 1-2 W type greenhouse which is made by rolling up and down the vinyl at upper part of column. Roof vents are installed at ridge, and thus external air inflow and natural ventilation are maximized. As the height increases, heating cost increase as well and, therefore, tomato greenhouse has been equipped with multi-layered thermal curtain, of which thermo-keeping is excellent, to prevent heat from escaping.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.6
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• pp.61-71
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• 2017

The tracer gas method has an advantage that can estimate total and local ventilation rate by tracing air flow. However, the field measurement using tracer gas has disadvantages such as danger, inefficiency, and high cost. Therefore, the aim of this study was to evaluate ventilation rate in pig house by using the thermal distribution data rather than tracer gas. Especially, LMA (Local Mean Age), which is an index based on the age of air theory, was used to evaluate the ventilation rate in pig house. Firstly, the field experiment was conducted to measure micro-climate inside pig house, such as the air temperature, $CO_2$ concentration and wind velocity. And then, LMA was calculated based on the decay of $CO_2$ concentration and air temperature, respectively. This study compared between LMA determined by $CO_2$ concentration and air temperature; the average error and root mean square error were 3.76 s and 5.34 s. From these results, it was determined that thermal distribution data could be used for estimation of LMA. Finally, CFD (Computational fluid dynamic) model was validated using LMA and wind velocity. The mesh size was designed to be 0.1 m based on the grid independence test, and the Standard $k-{\omega}$ model was eventually chosen as the proper turbulence model. The developed CFD model was highly appropriate for evaluating the ventilation rate in pig house.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.217-224
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• 1988

Changes in lipid components of Gul-bi, salted-dried yellow corvenia, during processing and storage were studied. Raw fishes contained $6.7\%$ total lipid (TL) which consisted of $83.3\%$ neutral lipid (NL), $6.5\%$ glycolipid (GL) and $10.2\%$ phospholipid (PL), and salted-dried sample at 30 days storage contained $11.1\%$ TL which consisted of $86.1\% NL, $7.1\%$ GL and $6.8\%$ PL. The NL was mainly consisted of trigly ceride (TG), free sterol (FS), free fatty acid (FFA), and the main lipids in PL were phosphatidyl choline (PC), phosphatidly ethanolamine (PE) and sphingomyelin (SPM). The contents of TG, PC, PE decreased, while that of FFA, SPM increased during processing and storage. Total fatty acid contents of raw fish, salted sample, salted-dried sample (product) and product at 30/days of storage were 847.9, 764.0, 633.5 and 588.mg/g-lipid, respectively, taking $C_{23:0}$ as the internal standard material. Most fatty acid con tents of TL revealed a tendency to decrease during processing and storage, highly unsaturated fatty acid such as $C_{22:6},\;C_{20:5}$, decreased largely. The major fatty acids in TL, NL, GL and PL were generally $C_{16:0},\;C_{16:1},\;C_{18:1},\;C_{20:5},\;C_{22:6}. Percentage of $C_{16:1},\;C_{18:1}$ in NL and GL and GL are higher than those in PL, while $C_{22:6},\;C_{20:5},\;C_{20:4}$. Peroxide value in salted-dried sample is 121.6 meq/kg and decreased rapidly with storage period, carbonyl value and brown pigment formation showed tendency of increase during processing and storage.