• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.50-66
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• 1998

This study was conducted to estimate crystalline silica contents in airborne respirable dust from various manufacturing industries and to compare analytical performance of two methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy (FTIR). For this study, various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: foundry, brick, potteries, concrete, and abrasive material, etc. Both personal and area respirable dust samples were collected using 10 mm, Dorr-Oliver nylon cyclone equipped with 37mm, $5{\mu}m$ pore size, polyvinylchloride (PVC) filters as collection media. In addition, total dust samples were collected side-by-side to the respirable samples. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 0500, 7500, and 7602 for dust collection and quartz analysis. In addition, bulk samples were collected and analyzed by X-ray fluorescence (XRF) for minerals. In this article, only the results obtained from foundry are reported. The results from various other industries will be published in future articles. The respirable dust concentrations from personal samples by cyclone were $0.46-1.06mg/m^3$ and those from area samples were $0.34-0.73mg/m^3$. Dust concentrations of personal samples were significantly higher than those of area samples. The highest dust concentration was obtained from the personal samples of the finishing operation. Total dust concentration ranged $1.24-3.40mg/m^3$. The mean quartz contents estimated by FTIR and XRD in the personal respirable dust samples were 5.12% and 4.41%, respectively, without significant difference between them. For quartz analyses, the two techniques were highly correlated with $r^2$ ranged 0.803-0.920. But the results by FTIR were mostly higher than those by XRD. In addition, cristobalite was not detected by FTIR. Significant correlations between contents of crystalline silica and such minerals as $Al_2O_3$, CaO, $TiO_2$, and $K_2O$ suggest possible interferences from these minerals.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.509-516
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• 2012

The aims of this research is to develop a fire resistant admixture to enhance high-pressured pumping of high-strength concrete (HSC) with a compressive strength of 60~80 MPa. Generally, the efficiency of HSC high-pressured pumping is dramatically reduced due to entanglement of short fibers added to prevent fire spalling. Therefore, the fire resistant admixture that can facilitate pumping of fire resistant HSC is urgently needed presently. The fire resistant HSC mix is comprised of Polypropylene fiber, Nylon fiber and Polymer powder. The test results showed that the slump-flow was improved by approximately 70% of the HSC without fire resistant admixture. However, the air void content was increased slightly due to the addition. The standard design compressive strength at 28-days was satisfied, while its flexural strength was similar to the concrete without the admixture. Since the flexural strength was 12~15% of its compressive strength, the general trend of flexural to compressive strength ratio in normal concrete was maintained. Even though its elastic modulus was decreased by adding the admixture, the study results showed that the concrete can be used for construction since all of the test results exceeded the code requirements.

• Journal of Aquaculture
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• v.20 no.4
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• pp.260-264
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• 2007

We investigated egg collection and the effects of water temperature (4, 7, 10, 13 and $16^{\circ}C$) on egg development, hatching and larval growth of Pacific cod Gadus macrocephalus under laboratory conditions. Fertilized eggs were round in shape ($1.01{\pm}0.03\;cm$) and adhesive to nylon nets. Fertilization rate was 68% by wet method. The time of egg development was negatively proportional to water temperature with the range of $4^{\circ}C$ to $13^{\circ}C$. Eggs hatched only at $7^{\circ}C$ after 288 hours of fertilization and $10^{\circ}C$ after 192 hours. Hatching rate was highest as 65% at $7^{\circ}C$ followed by $34.4^{\circ}C$ at $10^{\circ}C$. Survival rate was 18.3% at $7^{\circ}C$ and 5.2% at $10^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.673-679
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• 1998

The experiment was conducted to determine in situ rumen degradability of soybean meal (SM), fish meal (FM), sesame cake (SC) and Italian ryegrass hay (IRGH) and the effect of supplementing the above protein meals to IRGH on digestibility and balance of nutrients in three Saanen goats. For measuring the degradability, nylon bags containing each meal were incubated in the rumen of one fistulated dry cow for 3, 6, 12, 24, 36, and 48 hrs. Degradability revealed that SM protein was highly degradable in the rumen (99.1%), while FM protein was less degradable (76.8%) with SC protein being intermediate (91.2%) at 48 hrs of incubation (p < 0.01). Degradation rate of the potentially degradable fraction was estimated to be 12.12, 5.88 and 5.88%/hr for SM, FM and SC, respectively. In the metabolism trial, all goats were offered daily 900 g IRGH and one of the supplements, SM (100 g), FM (75 g) or SC (100 g). Intake of DM, OM, CP and GE was similar among diets. However, digestibility of OM for SC diet was significantly lower than that for diets supplemented with FM and SM (p < 0.10). Nitrogen (N) excreted in faeces (p < 0.05) and in urine (p < 0.10) was, respectively, higher and lower for SC diet than that for the other two diets. The same tendency was observed in energy losses in faeces (p < 0.10) and in urine (p < 0.05). There was no difference in energy loss in methane or in heat production among diets. Consequently, no significant difference was observed in N retention (2.13, 0.42 and -0.11 g/day for FM, SC and SM diet, respectively) or in energy retention (-1.49, -2.14 and -2.70 MJ/day for FM, SM and SC diet, respectively). These results showed that protein supplements affected the digestion of diets based on grass hay with 7.45% CP in DM in goats, although there was no significant influence on N or energy retention.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.4
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• pp.534-541
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• 2009

The aim of this study was to evaluate the effects of gamma irradiation (${\gamma}$-irradiation) at doses of 15, 30 and 45 kGy on chemical composition, anti-nutritional factors, ruminal dry matter (DM) and crude protein (CP) degradibility, in vitro CP digestibility and to monitor the fate of true proteins of full-fat soybean (SB) in the rumen. Nylon bags of untreated or ${\gamma}$-irradiated SB were suspended in the rumens of three ruminally-fistulated bulls for up to 48 h and resulting data were fitted to a nonlinear degradation model to calculate degradation parameters of DM and CP. Proteins of untreated and treated SB bag residues were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Digestibility of rumen undegraded CP was estimated using the three-step in vitro procedure. The chemical composition of raw and irradiated soybeans was similar. Results showed that phytic acid in ${\gamma}$-irradiated SB at dose of 30 kGy was eliminated completely. The trypsin inhibitor activity of 15, 30 and 45 kGy ${\gamma}$-irradiated SB was decreased (p<0.01) by 18.4, 55.5 and 63.5%, respectively. From in sacco results, ${\gamma}$-irradiation decreased (p<0.05) the washout fractions of DM and CP at doses of 30 and 45 kGy, but increased (p<0.05) the potentially degradable fractions. Gamma irradiation at doses of 15, 30 and 45 kGy decreased (p<0.05) effective degradability of CP at a rumen outflow rate of 0.05 $h^{-1}$ by 4.4, 14.4 and 26.5%, respectively. On the contrary, digestibility of ruminally undegraded CP of irradiated SB at doses of 30 and 45 kGy was improved (p<0.05) by 12 and 28%, respectively. Electrophoretic analysis of untreated soybean proteins incubated in the rumen revealed that ${\beta}$-conglycinin subunits had disappeared at 2 h of incubation time, whereas the subunits of glycinin were more resistant to degradation until 16 h of incubation. From the SDS-PAGE patterns, acidic subunits of 15, 30 and 45 kGy ${\gamma}$-irradiated SB disappeared after 8, 8 and 16 h of incubation, respectively, while the basic subunits of glycinin were not degraded completely until 24, 48 and 48 h of incubation, respectively. It was concluded that ${\gamma}$-irradiated soybean proteins at doses higher than 15 kGy could be effectively protected from ruminal degradation.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.376-380
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• 2006

An experiment was conducted to study the effect of temperature and pH on in vitro nutrient degradability, volatile fatty acid profile and methane production. The fermenter used was the semi-continuous system, known as the rumen simulation technique (RUSITEC). Sixteen cylinders were used at one time with a volume of 800 ml, the dilution rate was set at 3.5%/hour, the infused buffer being McDougall's artificial saliva. Basal diet (9.6 g DM) used in RUSITEC consisted of (DM) 6.40 g Timothy hay, 1.86 g crushed corn and 1.34 g soybean meal. The food for the fermentation vessel was provided in nylon bags, which were gently agitated in the liquid phase. The experiment lasted for 17 d with all the samples taken during the last 5 d. Treatments were allocated at random to four vessels each and were (1) two temperature levels of $39^{\circ}C$ and $41^{\circ}C$ (2) two pH levels of 6.0 and 7.0. The total diet contained ($g\;kg^{-1}$ DM) 957 OM, 115 CP and $167MJ\;kg^{-1}$ (DM) GE. Although increase in temperature from $39^{\circ}C$ to $41^{\circ}C$ reduced degradation of major nutrients in vitro, it was non-significant. Interaction effect of temperature with pH also reflected a similar trend. However, pH showed a significant (p<0.05) negative effect on the degradability of all the nutrients in vitro. Altering the in vitro pH from 7 to 6 caused marked reduction in DMD from 60.2 to 41.8, CPD from 76.3 to 55.3 and GED from 55.3 to 35.1, respectively. Low pH (6) depressed total VFA production (61.9 vs. 34.9 mM) as well as acetate to propionate ratio in vitro (from 2.0 to 1.5) when compared to pH 7. Compared to pH 7, total gas production decreased from 1,841 ml to 1,148 ml at pH 6, $CO_2$ and $CH_4$ production also reduced from 639 to 260 ml and 138 to 45 ml, respectively. This study supported the premise that pH is one of the principal factors affecting the microbial production of volatile fatty acids and gas. Regulating the ruminal pH to increase bacterial activity may be one of the methods to optimize VFA production, reduce methane and, possibly, improve animal performance.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.10
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• pp.1466-1473
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• 2013

This experiment was conducted to study the variation laws and correlations of shearing force and feed characteristics including morphological characteristic, chemical composition and in situ degradability of wheat straw. Feasibility of evaluating the nutritional value of wheat straws with shearing force values was analyzed in this study. Six hundred wheat straw plants (Jimai 22) were randomly selected and placed in a cool and ventilated place. Samples were collected in the 1st, 15th, 30th, 45th, 60th d after harvest to measure shearing force, morphological characteristic, nutritional composition. Rumen degradation of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of wheat straws were determined by the nylon bags method. The results demonstrated that linear and quadratic effects of storage time on all the tested morphological characteristics were significantly correlative (p<0.01). As storage time goes on, all the tested nutrients and their rumen degradations of wheat straw was linearly (p<0.01) and quadratic (p<0.01) correlative except ADF content and rumen degradation of ADF. Significant correlations were determined in linear effect of shearing force on morphological characteristics (p<0.01), and linear density and diameter were a more sensitive predictor than stem thickness for shearing force. There were strong correlations between storage time and all the measured physical characteristics (shearing force, morphological characteristics and shearing force standardized by morphological characteristics) (p<0.01). Nutrition compositions were linearly correlative with shearing force and standardized shearing force (p<0.01). The linear correlation between rumen degradation of DM and NDF and shearing force and standardized shearing force were evident (p<0.01). In conclusion, shearing force, nutrition compositions and their rumen degradation of wheat straw were still dynamic with storage time after harvest. Correlation could be found between shearing force and nutritional characteristics of wheat straw. Nutrient content, morphological index and rumen degradation of DM and NDF could be predicted by changes in shearing force. Shearing force should be applied according to a standardized storage time when it is used to forecast the feed value of wheat straws.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.13 no.3_4
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• pp.107-112
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• 2007

The effect of microwave heat to retort pouches and microwavable packages was examined. 186 products were collected, but packages were consisted of five package materials such as PET, Aluminum foil, Nylon, EVOH, and polypropylene. The results showed that all packages did not exceed the limits of current packaging regulation on consumption weight of $KMnO_4$, TDI(Toluene diisocyanate), and Caprolactam. Safety control on heat resistant packages considered satisfactory, but investigation on new substances should be continued for preventing any possible migration problems of packaged foods.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.99-111
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• 1999

The purpose of this study was to evaluate crystalline silica contents in airborne respirable dusts from various manufacturing industries and to compare analytical ability of two different methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy(FTIR). Various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: ceramics, brick, concrete, and abrasive material etc. The personal respirable dust samples were collected using l0mm, Dorr-Oliver nylon cyclone equipped with 37mm, $5{\mu}m$ pore size. polyvinylchloride (PVC) filters as collection media. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 7500, and 7602 for dust collection and quartz analysis. A total of 48 samples were collected from these industries. Initial analyses of these samples showed log-normal distributions for dust and quartz concentrations. Some results from ceramics and stone exceeded current Korean Occupational Exposure Limits. The average concentrations of personal respirable dust by cyclone were 0.43, 0.24, 0.26, 0.42, 0.53 and $0.29mg/m^3$ in ceramics, stone, concrete, glass, briquets, and others, respectively. A comparison of performance of two analytical methods for quantifying crystalline silica was performed using data from ceramics. The results showed that no significant difference was found between two methods for ceramics. The mean crystalline silica contents determined by XRD were 3.41 % of samples from briquets and 7.18 % from ceramics and were 2.58 % from concrete and 10.33 % from ceramics by FTIR. For crystalline silica analysis, two analytical techniques were highly correlated with $r^2=0.81$ from ceramics. Both cristobalite and tridymite were not detected by XRD and FTIR.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.246-249
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• 1994

Shelf-life of pork packaged under $CO_{2}$ was observed and the optimal volume of $CO_{2}$ gas was determined. High gas barrier film, EVOH($CO_{2}$ permiability; 1 $cc/cm^{2}{\cdot}24\;h{\cdot}atm$) was used as packaging material and the volume ratios of sample to $CO_{2}$ of 1 : 1, 1 : 3 and 1 : 5 were tried using the control of vacuum packaged pork. To ev.3luate quality of pork cuts, total plate counts, TBA, color and sensory score were monitored during the storage at $4{\pm}1^{\circ}C$ for 31 days. TPC of vacuum packaged pork increased up to $4.6{\times}10^{6}\;CFU/cm^{2}$ in 24 days while that of $CO_{2}$ gas packaged pork $4.5{\times}10^{5}\;CFU/cm^{2}$ at the same storage period, and it took 7 days more for gas packaged pork to reach the same TPC count. There was no significant difference in TBA value between vacuum packaged and gas packaged pork. In the color L and a values were not affected by treatment but vacuum packaged pork cuts showed higher b value than gas packaged pork. According to sensory evaluation, gas packaged pork showed less off flavor, better flavor and freshness than vacuum packaged one (P<0.05).