• Journal of Aquaculture
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• v.6 no.3
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• pp.199-211
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• 1993

In order to elucidate the effect of dietary n-3 highly unsaturated fatty acids (n-3HUFA) on the changes of body weight and chemical compositions in the Korean rockfish during starvation, the fish were not fed for 9 weeks after fed different levels $(0\~1.5\%)$ of n-3 HUFA for 10 weeks. The higher level of n-3HUF A was contained in the diets, the slower body weight loss was resulted (P< 0.05). The decreasing rates of the body nutrients of the fish were significantly higher in the fish fed n-3HUF A deficient diets than those of the fish fed n-3 HUF A sufficient diets. Protein and lipid contents of the whole body were decreased with starvation whereas moisture content was increased. Decrease of lipid was mainly due to the decrease of nonpolar lipid. Amounts of polar lipid in the whole body were almost constant throughout the starvation, meaning not being affected by dietary n-3HUF A levels. Percentage of 22: 6n-3 was increased in the polar lipid fraction, but monoenic acids (16:1, 18:1), n-3 series (18:3, 18 4, 20:4) and n-6 series (20:2, 22:4, 22:5) were decreased with starvation. Fatty acid compositions of nonpolar lipid were not changed with starvation. These results suggest that all fatty acids of nonpolar lipid are equally utilized for energy during starvation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.723-730
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• 2012

The radar cross section(RCS) of a trihedral corner reflector(TCR) should be accurately computed when it is used as an external calibration target for a satellite synthetic aperture radar(SAR) calibration campaign. This paper presents the RCS analysis on a trihedral corner reflector which is installed on a calibration site, using the wave reflection from the rough surface and the wave diffraction from the TCR edges. The results in this paper show quantitatively the effect of the front surface on the RCS of a TCR. The difference of the RCS between a TCR in air and a TCR on a ground surface is computed by including the interaction term which consists of the edge diffraction from the TCR edges and the surface reflection from the front rough surface. The reflection coefficient of a randomly rough surface is a function of the surface roughness and dielectric constant of the surface. The RCS of $10{\lambda}$ size TCR on a ground is 0.46 dB higher than TCR in air at 9.65 GHz, and this can reach at maximum 1.55 dB depending on a surface condition and TCR size. The effect of the front surface on the RCS of a TCR increases, as the surface roughness decreases, the soil moisture increases, and the size of TCR in wavelength decreases.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.242-248
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• 2017

This study was conducted to develop a cylindrical paperpot manufacturing equipment which is capable of continuously producing paperpots with a constant size. The equipment consists of the soil supply part, the paper supply part, the pot manufacturing part, the paperpot cutting part and its process for manufacturing paperpot from the soil supply to the paperpot cutting is continuously performed. As a result of the performance test using this equipment, we suggest that the optimal moisture content and injection pressure to supply soil are 50%~60%, and 0.5 Mpa respectively. Moreover the appropriate temperature for adhesive strength is $150{\sim}160^{\circ}C$ taking into account the performance of device and adhesion time. Also, considering the cutting speed and safety, it is appropriate to adopt a straight blade having a clean plan at a minimum angle of $30^{\circ}$. In addition, the manufacturing capacity of the developed equipment was 3300 pots per hour.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.930-937
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• 2016

This study investigated the quality characteristics, antioxidant activities, and retarding retrogradation of sponge cakes made with 0%, 1%, 3%, 5% and 7% pumpkin (Cucurbita moschata Duch.) leaf powder. Specific capacity significantly increased with the addition (0.33~0.38), but baking loss and dough yield were not significantly different (p<0.05). In color, there was a decrease in the L-value, a-value and b-value, but ${\Delta}E$ increased in proportion to the amount of pumpkin leaf powder. Moisture content increased in the 0~3% additions, from 27.90~31.68%, but decreased in 5% and 7% (22.37% and 28.15%, respectively). pH tended to decrease significantly according to the amount of pumpkin leaf powder (p<0.05). Hardness increased with the addition of pumpkin leaf powder, and pumpkin leaf groups presented higher springiness and cohesiveness than the control. Chewiness was not significantly differ (p<0.05). In retarding retrogradation, Avrami exponent (n) showed that addition of 5% (0.1329) had more retarding retrogradation effect than the control (0.4319), whereas time constant (1/k) showed both 3% (100.00) and 5% (70.42) addition had more effect than control (18.45). Total phenols and flavonoids content increased proportionate to the addition levels. ABTS radical scavenging activity tended to increase according to the level of pumpkin leaf powder. In sensory properties, 5% addition showed maximum color, and 3% addition had the highest scores in flavor, moistness, sweetness, chewiness and overall acceptability. These results suggested that pumpkin leaf was a good addition to improve the quality characteristics, health and sensory preferences. The most appropriate proportion to have the effect of retarding retrogradation in sponge cake is 3%.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.2
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• pp.227-235
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• 1993

This study was carried out to evaluate the possibility of composting for organic solid waste from restaurants and domestics. Small three vessels were prepared which were conditioned to semianaerobic, convectional and air-blowed type. During the experiment period for 4 months, the values of volatile solid(VS) %, moisture % and carbon/nitrogen (C/N) ratio of the wastes in the vessels were stabilized, 80 % to 40-50 %, 80 % to 48-55 % and 18 to 8-10, respectively. On the basis of VS % and C/N ratio, the reactions were more adaptable to 2nd order formula than to 1st order one, Reaction rate constant of the 3 vessels were estimated, $4.96{\times}10^{-5}(day^{-1})$ in the semianaerobic type, $5.82{\times}10^{-5}(day^{-1})$ in the convectional type and $8.42{\times}10^{-5}(day^{-1})$ in the air-blowed type on VS. Compared reaction rate constants(k), it can be said that composting period shorten if air is supplied artificially and that vessels simular to those of this study are useful for household organic waste at the backyards.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.69-77
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• 2004

Investigation of the time-dependent behavior of rock and the associated mechanisms are of key interest in long-term stability analysis of many engineering applications. In this study, creep tests were performed on Daejeon granite samples of 25.4mm diameter under uniaxial compression at varying stress levels. The effect of moisture was investigated by testing both air-dried and fully water-saturated samples. The creep behavior of Daejeon granite exhibited three distinctive stages of primary, secondary and tertiary creep. The ultimate strength of granite under a constant stress decreased considerably with time. Saturation and immersion of the test specimen in water markedly increased the total creep strain as well as the secondary creep rate. The experimental creep curves are fitted to Burger's model as well as two other empirical models suggested by previous researchers. A number of the parameters determined for each model are dependent on stress and influenced by the presence of water. Based on the experimental results, an empirical relation between the applied stress and the time-dependent strain is established separately for each air-dried and fully water-saturated Daejeon granite.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.299-307
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• 1988

Several experiments were conducted to investigate the effects of external factors on germination and emergence of Eclipta prostrata (L.)L. The weight of viable achenes doubled as a result of 90 minutes soaking in water. The germination of E. prostrata was significantly improved by alternating temperatures. At a constant temperature of $35^{\circ}C$, only 78% of the achenes germination, whereas at alternating temperatures of 35/$20^{\circ}C$, 96.5% of the achenes germinated. E. prostrata was more sensitive than rice to moisture stress. No germination of E. prostrata achenes occurred in the absence of oxygen. No germination of E. prostrata achenes occurred in the dark or when they were exposed to green, blue, and far-red light. Germination of E. prostrata achenes was influenced by the duration of illumination after absorption of water. Ten hours of illumination was needed for maximum germination and 2 hours for 50% germination. No significant changes in germination of E. prostrata achenes were observed between pH 3 and 10. A high tolerance of E. prostrata achenes to salt was observed. Emergence of E. prostrata achenes was greatly affected by planting depth. In the upland soil, 74.0% of the achenes planted on the soil surface germinated, and no emergence was at planting depths of 0.5 cm or greater.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.475-481
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• 1984

Estimation of the penetration rate of humectants has been considered to be important in effective control of food processing when intermediate moisture food is manufactured by the moist-infusion method. In this study, when shark (Isurus glaucus) muscle was soaked in four common humectants (sucrose, sorbitol, glycerol, and propylene glycol), the equation of their penetration rate was drawn as a function of time using high performance liquid chromatography analysis. Penetration rates increased with soaking temperatures and decreased inversely with molecular weights of humectants. The penetrated amounts for 10% humectant solution reached about equilibrium after soaking for 10 hours and for 30% humectant after soaking for about 7 hours. In consideration with the penetration rate of the sample soaked in 10% humectant and complex solution of each 10% humectant, little difference was found between them. When the sample was soaked in 10% humectant and 30% humectant, it seemed to be able to apply the following regression equation to estimate the penetrated amounts: M = a log (c.t)+ b where M = penetrated amounts; c = concentration of humectant; t= soaking time; a, b = constant and c.t should be within $10^3\;-\;4{\times}10^4$.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.61-67
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• 2018

Welding preheating means that the surface of the base material to which the metal is welded before the main welding is heated to a constant temperature. It prevents the cracks of the adjacent influences such as reduction of material hardening degree by controlling the cooling rate, suppression of segregation of impurities, prevention of thermal deformation, and moisture removal. For this reason, it is a necessary operation for high quality welding. Induction heating is an efficient heating method that converts electric energy into heat energy by applying electromagnetic induction phenomenon. Compared with combustion heat generated by gas and liquid, it is clean, stable, and economical as well as rapid heating. It can be heated regardless of the shape, depth and material of the heating body by modifying the shape of the frequency and the coil with a simple structure. In this paper, we implemented a low frequency welding preheating system using induction heating technique and observed the temperature changes of coil resistance, inductance and automotive transmission parts according to the height of each transmission in winding coil for three kinds of automotive transmission parts. We confirmed that the change of current is a very important factor in the low frequency heating.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.66-70
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• 1984

An attempt was made on the development of a commercial scale storage method of garlic by irradiation. Irradiated garlics with 50, 100 and 150 Gy were stored at natural low temperature storage room $(12{\pm}6^{\circ}C,{\;}75-85%{\;}RH)$ and the physicochemical properties during the 10 months storage were investigated. The unirradiated garlic was mostly sprouted after 8 months storage, whereas the sprouting of all irradiated groups was completely inhibited until 10 months storage, The rotting rate and weigh loss of garlic after 10 months storage were reduced by 25 to 54% at 100 Gy irradiation compared with those of an unirradiated group. The moisture content remained relatively constant during the whole storage period. The total sugar content was increased with storage period. Ascorbic acid content was also decreased until 8 months storage but its content was rapidly increased along with sprouting. Garlic was marketable after 10 months storage by 100 Gy irradiation combined with natural low temperature.