• Journal of the Korean Wood Science and Technology
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• v.35 no.3
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• pp.36-44
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• 2007

The purpose of this study was to investigate thermal stability, reactivity, and bonding strength of existing epoxy resin mixed with the epoxidized soybean oil (ESBO) in order to use soybean oil economically. In the dry shear test, the marked strengths showed $30.5kgf/cm^2$ at the ratio of ESBO to epoxy resin 9 : 1 and $6.2kgf/cm^2$ at the ratio 8 : 2. The bonding strengths of the others, except mixing ratios 2 : 8 and 1 : 9, exceeded the requirement of Korean plywood standard of $7.0kgf/cm^2$. In the wet shear test, the result was $5.8kgf/cm^2$ at the ratio 9 : 1. There were no thickness swelling and moisture absorption in the water resistance of the film. The value of activation energy, Tg (${\Delta}E$), by DSC analysis showed between $110^{\circ}C$ and $120^{\circ}C$ through all ratios. Epoxy in the epoxy resin fully reacted with the hardener (TETA), but it is difficult to decide that epoxys in the ESBO were reacted directly with the hardener from FT-IR analysis. As the mixing ratio of ESBO increased, the thermal stabilities dropped from TGA analysis. From the comprehensive view on the results of above experiments, it could be confirmed through experiments that the ESBO in the mixed adhesive of epoxy resin/ESBO played a role as an extending agent level of epoxy adhesive, and we were able to know that in order to utilize ESBO as an adhesive, a study should be performed on the condition of hardening, inducible of the hardening reaction.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.4
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• pp.258-263
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• 2019

Near infrared reflectance spectroscopy (NIRS) has become increasingly used as a rapid and accurate method of evaluating some chemical compositions in forages. The objective of this study was to evaluate the potential of NIRS, applied to imported forage, to estimate the moisture and chemical parameters for imported hays. A population of 392 imported hay representing a wide range in chemical parameters was used in this study. Samples of forage were scanned at 1 nm intervals over the wavelength range 680-2500nm and the optical data was recorded as log 1/Reflectance(log 1/R), which scanned in intact fresh condition. The spectral data were regressed against a range of chemical parameters using partial least squares(PLS) multivariate analysis in conjunction with spectral math treatments to reduced the effect of extraneous noise. The optimum calibrations were selected based on the highest coefficients of determination in cross validation(R²) and the lowest standard error of cross-validation(SECV). The results of this study showed that NIRS predicted the chemical parameters with very high degree of accuracy. The R² and SECV for imported hay calibration were 0.92(SECV 0.61%) for moisture, 0.98(SECV 0.65%) for acid detergent fiber, 0.97(SECV 0.40%) for neutral detergent fiber, 0.99(SECV 0.06%) for crude protein and 0.97(SECV 3.04%) for relative feed value on a dry matter(%), respectively. Results of this experiment showed the possibility of NIRS method to predict the moisture and chemical composition of imported hay in Korea for routine analysis method to evaluate the feed value.

• Food Science of Animal Resources
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• v.27 no.1
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• pp.29-34
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• 2007

We investigated the properties of pork jerky prepared under various drying conditions. Drying conditions were control ($80^{\circ}C$/210 min), T1 ($55^{\circ}C/60 min\to65^{\circ}C/60 min\to72^{\circ}C/90 min$), and T2 ($72^{\circ}C/90 min\to65^{\circ}C/60 min\to55^{\circ}C/60 min$), respectively. Water content and water activity ($a_w$) were the lowest in control, while TBA values were the highest among all groups (p<0.05). CIE $L^*$-value in T1 was significantly (p<0.05) lower than in T2 and CIE $a^*$-value showed significantly (p<0.05) the highest in control. CIE $b^*$-value in T2 were significantly higher (p<0.05) compared to the other treatments. Drying yields of pork jerky showed the lowest values in controls but highest in T2 jerky. In textual profile evaluations, control samples had greater hardness, cohesiveness, gumminess, and chewiness values than the other treatments, but springiness values were the lowest (p<0.05). Controls had significantly (p<0.05) lower scores than the other treatments in all sensorial traits. Total bacterial counts in T2 were the lowest during drying process. Based on our findings, we conclude that T2 conditions provided the most effective drying process.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.25-31
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• 1986

This study was conducted to determine the effects of 5 years continuous application of compost and rice straw with the different rates of nitrogen fertilizer on physico-chemical properties of paddy soils and yield of rice. The results obtained were as follows; 1. The yield of rice was 7 and 4% higher at straw and compost treatment compared to the non-application of organic matter. The rate of yield response for nitrogen fertilizer was lowered as the amount of nitrogen application increased under the condition of organic matter application. 2. Dry mayer weight and total nitrogen content of rice plants were increased in the order of straw > compost > non-application of organic matter. Above two factors were positive correlations with yield but total nitrogen content was negative correlation with ripening rate. 3. $NH_4-N$ in the soil was higher at plot applicated with compost and straw than non-application. It was positive correlation ($r=0.62^*-0.79^{**}$) with total nitrogen content in rice plants from 15 days after transplanting to heading stage. 4. The physical properties of soil, hardness and infilteration rate, after 5 years experiment, were improved in the order of straw > compost > non-application of organic matter. Organic matter content in the soil was decreased 0.1% on the straw treatment after 4 years, 0.1% on the compost after 3 and 4 years, and 0.1% on the non-application every years.

• Journal of Animal Science and Technology
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• v.47 no.5
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• pp.789-804
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• 2005

This study was conducted to determine effects of supplementation levels of aqueous direct-fed microbials (DFM; Bacillus spp.) to TMR(exp. 1.) and aqueous DFM addition under the various ratios of starch and cellulose(exp. 2.) on ruminal fermentation and fibrolytic enzyme activity. In experiment 1, ruminal fluids taken from rumen-cannulated Holstein cows were incubated during 24 hr by using TMR as substrates. Aqueous DFM was applied at a rate of 0, 0.025 and 0.05%, respectively. The pH of 0.025% treatment was not significantly different from that of control at 6 and 9 hr, but it was significantly lower (P<0.05) than 0.05% treatment. Concentrations of ammonia-N and VFAs were not affected by supplementing aqueous DFM. The A:P ratio of 0.05% treatment was significantly increased(P<0.05) by supplementation of aqueous DFM as compared with that of control at 24 hr. Although overall fibrolytic enzyme activities were not significantly affected by supplementing aqueous DFM, CMCase(carboxymethylcellulase) activity showed significant increase(P<0.05) compared to control at 6hr. However, the xylanase activity of 0.05% treatment significantly decreased(P<0.05) at 12 hr due to the application of aqueous DFM. There was no significant difference for in vitro dry matter disappearance among treatments. In experiment 2, ruminal fluids were incubated under the condition of various ratios of starch to cellulose(90:10, 70:30, 50:50, 30:70 and 10:90) with or without aqueous DFM(0.025%). Ruminal pH was unaffected by the addition of aqueous DFM, however, as increased level of starch, ruminal pH partially showed significant decrease(P<0.05). Ammonia-N concentration was not affected by aqueous DFM and ratio of starch and cellulose. On 9 hr incubation, DFM addition at a ratio of 70:30 showed significantly (P<0.05) lower value of ammonia-N(35.65 mg/dL) than that(65.05 mg/dL) of control. Concentrations of VFAs were significantly increased(P<0.05) by aqueous DFM addition compared with control at the same ratio on 6 hr incubation. The overall CMCase activity was not affected by aqueous DFM addition. However, the xylanase activity by aqueous DFM partially showed significant differences at the ratios of 90:10, 30:70 and 10:90. Our results indicated that supplementation of aqueous DFM did not significantly improve in vitro fermentation and fibrolytic enzyme activity. In addition, the DFM utilized in this study did not show consistent results by having various effects on ruminal fermentation under different feeding regimens.

• Journal of Animal Science and Technology
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• v.48 no.2
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• pp.219-226
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• 2006

The wastes (the needle leaves and branches) produced from thinning the forest were fermented under an anaerobic condition (pine silage) to utilize as a forage source of ruminants. An in situ trial was conducted with two ruminally fistulated Korean native cows by 4 replicates (2 bags per cow), and in vivo digestibility of pine silage was estimated with five Korean native steers by 5 replicates in incomplete double turn-over design. In order to investigate feed efficiency and carcass traits, forty eight Korean native bulls were assigned to four treatments (0%, 25%, 50%, 75% of pine silage) with a completely randomized design in 12 pens accommodating 4 animals per pen. The amounts of concentrate and roughage allowed to experimental animals were in the range of 2.5% and 0.6% of body weight, respectively. Animals had freely accessed to mineral block and water in stanchion barn.An in situ crude protein digestibility of the roughage sources when suspended for 48 hrs in the rumen was higher for feeding the pine silage than the rice straw, whereas NDF digestibility was vice versa. No differences between the treatments were observed in in vivo digestibilities of dry matter, crude protein and NDF. Daily body weight gain was significantly (P<0.01) higher for the pine silage substitutions compared with the rice straw feeding except for the 25% silage feeding. The pine silage feeding did not affect feed efficiency.In carcass traits, marbling score tended to be higher for the 50% pine silage treatment than the other treatments while back fat thickness tended to be the thinnest for the rice straw feeding. From these results, it may be recommended to substitute pine silage, as a forage source, for rice straw by 50 percent.

• Korean Journal of Environmental Agriculture
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• v.25 no.2
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• pp.138-146
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• 2006

To understand the status of water quality and work out a suitable countermeasures in Seonakdong watershed which has poor agro- environmental condition because of severe point and non-point source pollution by popularized city and near sea, we investigated the pollution sources and water quality from '03 and '05 and the result were mapped with GIS and RS for end-users's convenient comprehense and conjunction of water quality and geological data. The most degraded tributary was Hogeo stream which was affected directly by highly popularized Gimhae city, the main pollution source of the watershed. The pollution of tributaries in watershed increased the T-N of main body that reached over 4 mg/L during dry season. Pyeonggang stream and the lower part of main water way were suffered from high salt contents induced near sea and the EC value of those area were increased to 2.25 dS/m. The delivered loads of T-N and T-P were largest in Joman river as 56% and 61% of total delivered loads 1mm tributaries because of lots of stream flow. When Management mandate for irrigation water in Seonakdong river watershed was mapped for estimating integrated water quality as the basis of classification of EC and T-N contents in water, Hogeo and Shineo catchments were showed the requiring countermeasures none against nutrients hazard and Pyeonggang catchment was the vulnerable zone against nutrients and salts hazard. As the result, Seonakdong watershed had very various status of water quality by characteristics of catchments and countermeasures for improving water quality and crop productivity safely should changed depend on that.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.303-313
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• 2008

This research is aimed to investigate the cultivation method of oyster mushroom[Pleurotus ostreatus (Jacq. ex Fr.) Kummer] at the non-sterilized medium with $Ca(OH)_2$ treatment. Therefore, experiments were carried out to develop non-sterilization method of medium by addition of $Ca(OH)_2$ for omission of heat sterilization progress of medium. General components, minerals and amino acid in Jiri wild type No. 1 (Pleurotus ostreatus) and production cost were analyzed. For the purpose of omission of heat sterilization progress, treatment ratio of $Ca(OH)_2$ (purity 95%) was 5%(w/w) of dry medium. Initial pH of this medium was 11 and then the pH was changed by 9 after the uniform mixing of the medium for half an hour. The various germs occurred 50% and 100% at pH 8 and pH 7 of the non-sterilized medium, respectively. Production of oyster mushroom increased by $2,030\;ton\;ha^{-1}$ when the main raw material used corn pith instead of waste cotton. The time required of mycelium culture was 30 days when hypha was cultured at the non-sterilized medium, and pinhead occurred when 2 or 3 days was passed after the time required of mycelium culture. Occurrence of pinhead was most rapid at the condition of $22{\sim}26^{\circ}C$, 65% humidity and pH $6.5{\sim}7.0$ and required of $22{\sim}28$ days at $70{\sim}80\;mm$ thickness of non-sterilized medium. Ca content in 1st harvest oyster mushroom was higher than that in 2nd harvest one, and its difference was $30.3\;mg\;kg^{-1}$. Amino acid content by stipe thickness of oyster mushroom was ranged from 411.2 to $343.9\;mg\;kg^{-1}$ both in a pileus and a stipe of 1st harvest mushroom, and from 402.4 to $498.2\;mg\;kg^{-1}$ and from 442.6 to $470.4\;mg\;kg^{-1}$ in those of 2nd harvest one, respectively. The results of the present study suggest that the non-sterilization medium by addition of $Ca(OH)_2$ is usable with the cultivation of oyster mushroom.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.1
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• pp.28-34
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• 2017

A new naked oat cultivar, 'Jungmo2005'(Avena nuda L.), was developed for food and forage use by National Institute of Crop Science, RDA in 2010. It was derived from a cross between $F_1$['Early80'/'Gwiri33'] and $F_1$['Early80'/'Gwiri23']. 'Early80', a covered oats, has early heading and high yielding, while 'Gwiri23' of covered type and 'Gwiri33' of naked type has early heading with large-size grain. 'Jungmo2005' has the characteristics of narrow and long leaves of pale green color, middle diameter culm of yellow color and medium grain of whitish yellow color. Cultivar 'Jungmo2005' had 2 days earlier heading date (May 9) than the check cultivar 'Seonyang' (May 11) in field condition. The 'Jungmo2005' showed better winter hardiness than that of the check cultivar, and similar to the check cultivar in respect to lodging resistance. The 'Jungmo2005' had 105 cm of culm length, 21.5 cm of spike length, 658 spikes per $m^2$, 82 grains per spike, 23.3 g of 1,000-grain weight, and 622 g of test weight. The grain yield of 'Jungmo2005' was averaged $3.38MT\;ha^{-1}$, which was 6% higher than that of the check. Average forage fresh and dry matter yield of 'Jungmo2005' harvested at milk-ripe stage were 44.8 and $12.6tone\;ha^{-1}$, respectively, compared with 47.5 and $12.5tone\;ha^{-1}$ of the check. The protein content of the 'Jungmo2005' was similar to the check (7.6% and 7.5%, respectively), while ADF (28.6%) and NDF (51.5%) were lower than the check (31.4% and 57.0%, respectively). TDN content and RFV were higher than those of the check (66.3%, 120.3 and 64.1, 105.2, respectively). 'Jungmo2005' is recommended for fall sowing cropping only in the south area where daily minimum mean temperatures are averaged higher than $-4^{\circ}C$ in January, and it should not be cultivated in mountain areas, where frost damages is likely to occur. The areas would do better only to sow in spring season.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.481-490
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• 2003

The objectives of this study are (1) to determine the extent and degree of As contamination of the water and sediments influenced by mining activity of the abandoned Au-Ag mines, (2) to examine As speciation In contaminated water, (3) to monitor variation of As contamination in water system throughout the dry and wet seasons, and (4) to investigate the As chemical form in the sediments through the sequential extraction analyses. Natural water(mine water, surface water and groundwater) and sediments were collected in six abandoned Au-Ag mine(Au-bearing quartz veins) areas. The contamination level of As in mine water of the Dongil(524${\mu}m$/L) is more higher than the tolerance level(500 ${\mu}m$/L) for waste water of mine area in Korea. Elevated levels of As in stream water were also found in the Dongil(range of 63.7∼117.6 ${\mu}m$/L.) and Gubong(range of 56.1∼62.9 ${\mu}m$/L) mine areas. Arsenic contamination levels in groundwater used by drinking water were more significant in the Dongil(11.3∼63.5 ${\mu}m$/L), Okdong(0.2∼68.9 ${\mu}m$/L) and Gubong(2.0∼101.0${\mu}m$/L) mine areas. Arsenate[As(V), $H_2AsO_4^-$] is more dominant than arsenite[As(III), $H_3AsO_3$] in water system of the most mine areas. The concentration ratios of As(III) to As(total), however, extend to the 95% in stream water of the Okdong mine area and 70∼82% in groundwater of the Okdong and Dongjung mine areas. As a study of seasonal variation in the water system, relatively high levels of As from the dongil mine area were found in April rather than in September. Sequential extraction analysis showed that As was predominantly present as coprecipitated with Fe hydroxides from sediment samples of the Dongjung and Gubong mine(35.9∼40.5%), which indicates its possibility of re-extraction and inducing elevated contamination of As in the reductive condition. In sediments from the Dongil, Okdong and Hwachon mine area, high percentage(55.2∼83.4%) of As sulfide form was found.