• Applied Biological Chemistry
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• v.34 no.2
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• pp.154-161
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• 1991

An objective method for measuring rancidity in soybean oil was developed based on the volatile contents obtained by headspace gas chromatographic analysis. Apparatus for headspace volatile cold trapping-thermal desorption was described, designed to collect and analyze volatiles of soybean oil. Samples of commercially processed soybean oil were stored under controlled condition and then evaluated for flavor by a eight member trained panel and for volatile contents by headspace gas chromatographic analysis. Twenty-three GC peaks were identified on the basis of relative retention time of reference compounds and gas chromatography-mass spectrometry. The volatile compounds identified were autoxidation products of principal unsaturated fatty acids of soybean oil. The simple linear regressions of flavor score with the pentanal or hexanal contents in aged soybean oil gave correlation coefficient of 0.990 and 0.994. respectively. Pentanal and hexanal contents could be used as a potentially useful index for predicting flavor scores of soybean oil.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1627-1634
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• 2017

In this work, a junctionless transistor with different film thickness of amorphous InGaZnO has been fabricated and it's instability has been analyzed with different film thickness under positive and negative gate stress as well as light illumination. It was found that the threshold voltage shift and the variation of drain current have been increased with decrease of film thickness under the condition of gate stress and light illumination. The reasons for the observed results have been explained by stretched-exponential model and device simulation. Due to the reduced carrier trapping time with decrease of film thickness, electrons and holes can be activated easily. Due to the increase of vertical channel electric field reaching the back interface with decrease of film thickness, more electrons and holes can be accumulated in back interface. When one decides the film thickness for the fabrication of junctionless transistor, the more significant device instability with decrease of film thickness should be consdered.

• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.400-407
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• 2002

Two dimensional solitary waves are stably propagated in a saturable medium which has a saturable nonlinear index as input intensity. However, in the case of low intensity. a negative fifth-order nonlinear medium has properties of a saturable medium. So a Gaussian beam travels stably. The propagation process into the fifth order nonlinear medium of the Gaussian beam with a weak intensity is investigated by using the computer simulation of the two-dimensional nonlinear Schrodinger equation. As a result, it is confirmed that the two-dimensional spatial solitary waves are stably propagated in this medium when the incident powers are self-trapping powers. In the condition of the phase difference and collisional angle between two input beams of 180 degree and 0.05 degree, respectively, we can confirm that all optical switching is as simple as controlling the incident power of one input beam.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.466-471
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• 2007

The purpose of study is to obtain basic but important information for the operation of the greenhouse facility located in the suburb of town. Special emphasis is given on the aspect of energy saving method, which can be easilyapplicable in a practical sense. For this end numerical calculation has been made systematically in order to increase the energy efficiency by the evaluation of the temperature distribution in greenhouse. Major parameters considered are primarily the overall shape of greenhouse together with the various conditions of baffle installion inside greenhouse. Further, the performance of heating system is also carefully compared each other for a number of typical arrangements of heating duct. The performance of the computer program developed in this study is evaluated by the observation of the famous fluid trapping phenomenon occurred in staggered baffle condition in the enclosure of greenhouse. Based on the this study, a number of useful conclusions can be drawn, that is, the installation of baffles are quite effective in energy saving method with a minor modification of facility. Also, it is found that the change of the heating duct system can contribute significantly to the uniform temperature distribution in greenhouse. Further other findings obtained by numerical calculation were not only physically consistent and meaningful but also useful for the determination of optimum condition of practical operation of greenhouse.

• KSBB Journal
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• v.25 no.2
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• pp.155-166
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• 2010

Studies on the production of cell-wall bound innerpolysaccharides (IPS) (soluble ${\beta}$-D-glucan) have been performed by use of suspended myelial cultures of Inonotus obliquus. This product has promising potentials as an effective antidiabetic as well as an immunostimulating agents. As a first step to enhanced production of IPS, Intensive strain improvement programs were carried out by obtaining a large amounts of protoplasts for the isolation of single cell colonies. Rapid and large screening of high-yielding producers was possible because about fivefold higher amount of protoplasts ($2.3{\times}10^6$ protoplasts/mL) could be recovered with relatively high regeneration rates of $10^{-2}{\sim}10^{-3}$ by applying a modified filtration method, as compared to the previously used trapping method. A basic protocol necessary for UV-mutation of the protoplasts was also developed, resulting in several overproducing variants with good fermentation properties. Since the amount of IPS extracted from the mycelial cell walls of I. obliquus turned out to be almost constant per g DCW, increase in cell mass was considered the most important factor for the enhancement in IPS production. Therefore, attempts were made to screen mutant cells showing rapid mycelial growth rate in the final suspended cultures. Notably, the mutant strains showing an active cellgrowth in the preceding solid growth cultures were observed to produce higher amount of IPS in the suspended fermentations as well. A striking mutant, OBLQ756-15-5 strain, obtained from the survivors of a harsh UV-treated condition (97% death rate) was found to stably produce as high cell mass as 22 g DCW/L in the final fermentations. Currently, this strain is being tested for development of a scaled-up fermentation process for mass production of IPS.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.1
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• pp.9-26
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• 1997

Stokes drift(SD) and Lagrangian discharge(LD) are important factors for analysis of flushing time, tidal exchange, solute transport and pollutant dispersion. The factors should be calculated using the approached method to flow phenomena. The aim of this paper re-examines the previous procedures for computing the SD and LD, and is to propose the new method approached to stratified flow field in the cross-section of coastal region, e.g. Masan Bay. The intensity of velocity near the bottom boundary layer(BBL) depends on the sea-bed irregularity in the coastal estuaries. So we calculated the depth mean velocity(DMV) considering that of BBL omitted in Kjerfve's calculation method. It revealed that BBL effect resulting in application of the bay acts largely on DMV in half more among 1l stations. The new expression of SD and LD per unit width in the cross-section using the developed DMV and proposed decomposition procedure of current were derived as follow : $$Q=u_0+\frac{1}{2}H_1{U_1cos(\varphi_h-\varphi_u)+U_3cos(\varphi_h-\varphi{ud})} LD ED SD$(Q_{skim}+Q_{sk2}) The third term, $Q_{sk2}$, on the right-hand of the equation is showed newly and arise from vertical oscillatory shear. According to the results applied in 3 cross-sections including 11 stations of the bay, the volume difference between proposed and previous SD was founded to be almost 2 times more at some stations. But their mean transport volumes over all stations are 18% less than the previous SD. Among two terms of SD, the flux of second term, $Q_{skim}$, is larger than third term, $Q_{sk2}$, in the main channel of cross-section, so that $Q_{skim}$ has a strong dependence on the tidal pumping, whereas third term is larger than second in the marginal channel. It means that $Q_{sk2}$ has trapping or shear effect more than tidal pumping phenomena. Maximum range of the fluctuation in LD is 40% as compared with the previous equations, but mean range of it is showed 11% at all stations, namely, small change. It mean that two components of SD interact as compensating flow. Therefore, the computation of SD and LD depend on decomposition procedure of velocity component in obtaining the volume transport of temporal and spacial flow through channels. The calculation of SD and LD proposed here can separate the shear effect from the previous SD component, so can be applied to non-uniform flow condition of cross-section, namely, baroclinic flow field.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.21-27
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• 1993

Fluid inclusion has been widely used to study the origin and physiochemical conditions of ore deposits. However, it is difficult to get the accurate physiochemical data from fluid inclusion study due to the error of microthermometric data and the complexity of calculation of density and isochore of fluid inclusion. The computer programs HALWAT, $CO_2$, and CHNACL written by Nicholls and Crowford (1985) partly contributed to improve the accuracy of physiochemical data by using complicated equations. These programs are applied to determine the densities and isochores of fluid inclusions for the Cretaceous Keumhak mine using Choi and So's data (1992) and for the Jurassic Samhwanghak mine using Yun's data (1990). The estimated PoT for Keumhak mine from calculated isochores of coexisting fluid inclusions are $230^{\circ}{\sim}290^{\circ}C$ and 500~800 bar which matche well to the poT estimated by Choi and So ($280^{\circ}{\sim}360^{\circ}C$ and 500~800 bar, 1992). However, the poT for Samwhanghak mine estimated in this study by combining the calculated isochores and sulfur isotope geothermometer data by Yun (1990) are about 4~7 kb at $329{\pm}50^{\circ}{\sim}344{\pm}55^{\circ}C$ which are quite different form the P-T estimates by Yun ($255^{\circ}{\sim}294^{\circ}C$ and 1.2~1.9kb, 1990). This discrepancy caused by misinterpretation of homogenization temperature (Th) of fluid inclusion and by application of inappropriate isochores. The application of homogenization temperature and/or inappropriately selected isochore to determine the trapping PoT condition of ore-deposits should be avoided, particularly for ore-deposits formed at pressures higher than 1~2 kb.

• Journal of Animal Science and Technology
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• v.53 no.1
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• pp.51-57
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• 2011

The performance of grass filter strips (GFS) in abating $NO_3$-N concentrations from the forage cropland was tested in an experiment on the 10% slope in Grassland and Forages Division, National Institute of Animal Science, Rural Development Administration (RDA) from October 2007 to September 2009. Forage croplands with rye-corn double cropping system applied with chemical fertilizer and livestock manure (LM) were compared in a natural condition. The plots were hydrologically isolated in a randomized block layout of 3 treatments $\times$ 2 factors $\times$ 3 replicates. Main plots consisted of the length of GFS, such as 0 m, 5 m, 10m and 15m. Sub plots consisted of the type of LM, such as chemical fertilizer (CF), cattle manure (CM) and swine manure (SM). Dry matter yields of rye and corn increased significantly in order of CF > CM > SM (p<0.05). Concentrations of $NO_3$-N in surface runoff water were reduced as the length of GFS increased. Especially, GFS with 10 m and 15m reduced $NO_3$-N concentrations significantly compared to that with 0 m and 5 m (p<0.05). The results from this study suggest that GFS improved the removal and trapping of manure nutrients from forage croplands.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.4
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• pp.309-316
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• 2010

The performance of grass filter strips (GFS) in reducing $PO_4$-P concentrations and soil loss from the forage cropland was tested in an experiment on the 10% slope in Grassland and Forages Division, National Institute of Animal Science, Rural Development Administration (RDA) from October 2007 to September 2009. Forage cropland with rye-corn double cropping system receiving inorganic fertilizer or livestock manure (LM) were compared in a natural condition. The plots were hydrologically isolated in a randomized block layout of 3 treatments $\times$ 2 factors $\times$ 3 replicates. Main plots consisted of the length of GFS, such as $25\;m^2$ ($5{\times}5\;m$), $50m^2$ ($5{\times}10\;m$), $75m^2$ ($5{\times}15\;m$). Sub plots consisted of the type of LM, such as chemical fertilizer (CF), cattle manure (CM) and swine manure (SM). Concentrations of $PO_4$-P in surface runoff water were reduced as the length of GFS increased. Especially, GFS with 10 m and 15 m reduced $PO_4$-P concentrations significantly compared to that with 0 m (p<0.05). However, there was not significant different between $PO_4$-P concentrations of GFS with 10m and that of GFS with 15 m. Moreover, Soil loss in surface runoff water were reduced as the length of GFS increased. GFS with 15 m reduced soil loss significantly compared to that with 5 m and 10 m (p<0.05). The results from this study suggest GFS improve the removal and trapping $PO_4$-P and soil loss from forage cropland.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.202-211
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• 2011

The geometric characteristics of step-pool structures and how they are influenced by channel characteristics were investigated in a steep mountain stream in the Experimental Forests of Kangwon National University in Chuncheon, Gangwon-do. Average values of steps for the study reaches were as follows: step spacing, 4.69 m; step height, 0.47 m; step drop, 0.71 m; step-forming particle sizes, 0.68 m; number, 21steps/ 100 m; the ratio of step spacing to channel width, 0.5; and step steepness, 0.13. Relationships between spacing and height of steps and channel gradient showed a negative- and positive correlation, respectively, whereas all geometric variables of steps manifested poor correlation with channel width. Therefore, step steepness, expressed as the ratio of step height to step spacing, increased as channel gradient increased. The ratio of step steepness to channel gradient representing the criterion of maximum flow resistance was 1.2, indicating the channel bed's stable condition. In particular, the relationship between the ratio of step drop to step height and channel gradient showed a significant negative correlation, suggesting the influence of step-pool geometry in trapping sediment and providing an aquatic habitat. Positive correlations also exist between spacing and drop of steps and step particles. Our findings suggest that the dynamics of step-pool structures may strongly control physical and ecological environments in steep mountain streams, so understanding them is essential for stream management.