• Food Science of Animal Resources
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• v.41 no.1
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• pp.45-58
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• 2021

This study investigated the dietary effect of total mixed ration (TMR) based on high roughage content on the growth performance, carcass characteristics, and meat quality of Hanwoo steers. Twenty-four Hanwoo steers (average body weight, 195.3±4.7 kg; age, 8.5 mon) were randomly allocated to three experimental groups according to forage and concentrate ratio (DM basis): 25:75 (control), 50:50 (T50), and 70:30 (T70). Productivity in the fattening period and final body weight were significantly higher in the control. Average daily gain and feed conversion ratio were the same among treatments. Serum parameters, cholesterol, blood urea nitrogen, and total protein were higher in the control. Carcass weight was comparable in the control and T50 but feeding more roughage was significantly correlated with a higher intramuscular fat. Shear strength and drip loss were higher while n-6/n-3 was lower in T70 compared to the other groups. However, meat color was not significantly different among treatments. In terms of free amino acid contents, glutamic acid and glycine were higher in the control than T50 and T70. Overall, feeding Hanwoo steers with high forage content TMR had the lowest n-6/n-3 ratio of fatty acid content but highest intramuscular fat, shear strength, and drip loss. High forage content TMR is the best feed for Hanwoo steers that gives more benefits for human health and consumption but also provides the best meat grade and quality, which is important in the beef market in Korea.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.180-187
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• 2015

This study was conducted to determine the effects of feeding by-product feed (BF)-based silage on the performance, blood metabolite parameters, and carcass characteristics of Hanwoo steers. The BF-based silage was composed of 50% spent mushroom substrate, 21% recycled poultry bedding, 15% cut ryegrass straw, 10.8% rice bran, 2% molasses, 0.6% bentonite, and 0.6% microbial additive (on a wet basis), and ensiled for over 5 d. Fifteen steers were allocated to three diets during the growing and fattening periods (3.1 and 9.8 months, respectively): a control diet (concentrate mix and free access to rice straw), a 50% BF-based silage diet (control diet+50% of maximum BF-based silage intake), and a 100% BF-based silage diet (the same amount of concentrate mix and ad libitum BF-based silage). The BF-based silage was fed during the growing and fattening periods, and was replaced with larger particles of rice straw during the finishing period. After 19.6 months of the whole period all the steers were slaughtered. Compared with feeding rice straw, feeding BF-based silage tended (p = 0.10) to increase the average daily gain (27%) and feed efficiency (18%) of the growing steers, caused by increased voluntary feed intake. Feeding BF-based silage had little effect on serum constituents, electrolytes, enzymes, or the blood cell profiles of fattening steers, except for low serum Ca and high blood urea concentrations (p<0.05). Feeding BF-based silage did not affect cold carcass weight, yield traits such as back fat thickness, longissimus muscle area, yield index or yield grade, or quality traits such as meat color, fat color, texture, maturity, marbling score, or quality grade. However, it improved good quality grade (1+ and 1++) appearance rates (60% for the control group vs 100% for the BF-based silage-fed groups). In conclusion, cheap BF-based silage could be successfully used as a good quality roughage source for beef cattle.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.71-76
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• 2010

The use of advanced high-strength steels (AHSS) in automotive applications has steadily increased over the past few years. Two different failure modes are generally observed in shear-tension tests for resistance spot welds of AHSS. interfacial fractures and full button pullout. Despite high load-carrying capacity. the resistance spot welds in AHSS cue prone to interfacial fractures. To improve the load carrying ability of welds during shear-lap and cross tension tests. the tip surface of the electrode was grooved in a round shape. The electrode tip surface was modified so as to concentrate the current now in the central and circumferential portion of the electrode force. The results showed that the interfacial fracture was suppressed in welds using the modified electrode. In a comparison of failure mode during mechanical tests. the welds made with the modified electrode showed a higher tendency to fail via full button pullout fracture.

• Resources Recycling
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• v.19 no.2
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• pp.35-44
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• 2010

As the competition of acquiring foreign resources of advanced countries and developing countries intensifies, South Korea which imports most of the mineral resources, started to re-develop domestic mines for molybdenite ore, in order to secure stable natural resources and decrease foreign currency expense. In this study, as a result of performing XRD and composite analysis on Dongwon NMC's (the sole producer of molybdenite ore in Korea) final concentrate(Mo 50.4%), Quartz, Grossular and Hedenbergite exists as impurities and size analysis showed that in relative coarse particle range of 60~140 mesh was formed with high grade over 57% Mo. Also, a test was performed to confirm the possibilities of increasing the grade and recovery of Dong won NMC's final ore. As a result, Mo 58.6% ($MoS_2$ 97.83%) was obtained with 87.47% recovery at a condition of 15 minutes grinding time, Kerosene as collector 0.1 l/ton, AF as Frother 65 7.2 l/ton, wash water of 630 ml/min and air flow rate of 1,197 ml/min.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.838-843
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• 2002

The objectives of this study were to examine growth performance and meat quality by three different feeding patterns in Korean native cattle (KNC). In each of 3 years, fifteen KNC were randomly assigned in a (3 feeding management)${\times}$(3 sex) factorial design experiment; thus, in total, there were 5 animals in each of the 9 treatments. The three feeding management treatments were longterm (24 month) restriction feeding (LTFR), long-term restriction feeding-hormone implant (LTFR-tH), and short-term (18 month) nonrestriction feeding (STFNR). Three sexes were bull, steer, and heifer. Concentrate diet was fed restriction-feeding method based on body weight in LTFR and LTFR-tH. However, the diet was fed ad libitum in STFNR. Hormonal implantation was made three times with M-$PO^{TM}$ for bulls and with F-$TO^{TM}$ for heifers at 18, 20, 22 month of age in LTFR-tH. Animal were purchased from the local cattle market and managed in two local farms and at the university research unit. Animals were slaughtered at 24 months for long-term trial and at 18 month for short-term trial. The growth rate was the highest in bulls and the lowest in heifers. However, the differences were diminished in F-$TO^{TM}$ implanted heifers. The average daily gain was high in STFNR due to ad libitum feeding. The carcass grade was similar among the treatments on percentage bases. Hormonal implants improved significantly the meat quality grade in all sexes. Castration increased body fat content and improved meat quality grade by intramuscular fat deposition. In conclusion, long-term feeding and hormone treatment increased meat quality grade more than short-term feeding. However, ADG was higher in the short-term trial although feedefficiency was lower.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.344-350
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• 2018

This study was carried out to improve the forest management method considering the use of high value added timber in the natural broadleaf forests. For this purpose, the criteria for evaluating the quality grade of standing trees were established and applied to the oak stand in the central region of Korea. The evaluation factors of the grade were bending of stem, branch, stem damage, and other defects. If the logs are divided into 2.1 m units and three logs up to 6.3 m are available, they are classified as Grade I (G-I). If two logs are available, they are classified as Grade II (G-II), If only one log is available, it is classified as Grade III (G-III). When any log is not available as timber, it is classified as Grade IV (G-IV). As a result of applying the grade to the oak stand, G-I was 6.7 %, G-II was 28.0 %, G-III was 38.3 %, and G-IV was 27.0 %. The ratio of standing trees by oak species of higher than G-III was 88.2 % for Quercus acutissima, 88.1 % for Q. variabilis, 83.5 % for Q. serrata, 56.3 % for Q. aliena, and 50.3 % for Q. mongolica, respectively. The G-IV ratio for Q. variabilis and Q. mongolica tended to decrease with increasing diameter at breast height. The order of major defect affecting the grading level was bending of stem > branch > stem damage > other defects. Considering the grade level and oak species distribution, it was concluded possible to produce high quality hardwood timber when we concentrate forest tending techniques on Q. acutissima and Q. variabilis stand. In order to improve the accuracy of grading, it is necessary to continuous complement through the monitoring research for evaluation factors.

• Journal of Industrial Technology
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• v.7
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• pp.27-47
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• 1987

Fine anthracite is very difficult to upgrade by conventional processes such as gravity concentration or froth flotation, because large quantities of fine coals are generated at the mining and preparation stages and a significant portion of these fine coals are mixed with gangue minerals. This study, therefore, was carried out for the purpose of improving recovery of low ash clean coal, effective beneficiation of low-grade coking coal and removal of sulphur from high-sulphur coals by employing the method of selective agglomeration using oil or polystrene flocculants, for coals which are generally hydrophobic in nature will be extracted by using flocculants. Studies were performed by varying solid concentration, concetration of bridging liquid, mixing speed and mixing time, balling speed and balling time, dispersant dosage, flocculant dosage, pulp pH, and particle size. The results were : when the methods of the oil agglomeration and selective flocculation were employ(in the two process the sample was ground to the size of -74 micron), 1) ash content of the agglomerated coal was 9.85, 7.83%, 2) combustibel recovery of it was 98.5%, 93.5%, respectively. It was observed in selective flocculation that polystyrene is an effective flocculant for coal, De-entrapment of shale from the concentrate flocculated by mechanical agitation was necessary for substantional reductions in final ash content.

• The Journal of Pediatrics of Korean Medicine
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• v.21 no.3
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• pp.125-143
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• 2007

Objective The purpose of this study was to investigate health and life style of pediatric outpatients who visited the oriental hospital. Methods The study was composed of 363 students from elementary school, middle school and high school who visited the pediatrics department in $\bigcirc\;\bigcirc$ university oriental medicine hospital between 2005 and 2006. Results 1. The group wasconsisted with 56% of male and 44% of female student and for the age distribution, 7.4% were elementary school students, 55.6% were middle school students, and 36.9% were high school students. 2. Usually the eldest child tends to visit hosipital more than the younger ones. 3. More than a half of those students' parent had University education or beyond that. 4. There were more students who had below the level of the height-weight curve than in the higher level. 5. The average study hours of the students were 3.67 hours. An average sleep hours was 6.18 hours. An average exercise hour was 1.16 hours and an average time for watching TV was 1.71 hours. 6. Many students had hard time to concentrate on the studying for a long time. 7. For the question about the reason why they got the poor grade, they answered because of the lower concentration, and they didn't put much effort on the studying. The most they concern about was their grade. 8. Most of the students who visited the clinic said they did not feel refreshed when they woke up in the morning, and, many of them said that they don't feel okay. 9. More than an half of the students wear glasses. 10. More than an half of the students answered that they often catch a cold when the weather changes a lot. 11. A lot of them had some digestive problems. 12. As they getting older, they said they often feel back pain and shoulder pain. 13. Many students felt irritated and got mad easily. Many of them felt bored about their study and stressed out because of their tests and the university entrance exams. 14. Most of the female students answered that they have irregular period or cramps. 15. 21% of them usually skip breakfast. 16. Many students enjoyed snacks. Most of them enjoyed snacks after school. As they go into higher grade, they would like to eat at night especially cookies, bread and fruits. Conclusions Further studies with larger sample size of students will be neededfor accurate results, and it would be better if we can compare the conditions of the students before treatments and after those.

• Journal of Animal Science and Technology
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• v.52 no.4
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• pp.305-312
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• 2010

Seventy two Hanwoo steers in final fattening period ($585.87{\pm}41.02kg$) were randomly assigned to 3 groups, LPLT (relatively low protein and low energy; CP 12%, TDN 73%), LPHT (relatively low protein and high energy; CP 12%, TDN 75%) and HPHT (relatively high protein and high energy; CP 14%, TDN 75%) in concentrate feed for 163 days in order to investigate the effects on growth performance, carcass characteristics, and longissimus dorsi muscle's chemical compositions. Rice straw was also fed as a roughage. Because ADGs were higher in LPLT and HPHT than LPHT, feed efficiencies were improved in LPLT and HPHT group (P<0.05). Feeding concentrates with different CP and TDN levels had affected to improve back fat thickness and rib eye area in HPHT group but had no effect on carcass weight and meat yield index. Carcass weight for LPLT, LPHT and HPHT were $420.75{\pm}30.56$, $417.05{\pm}32.03$ and $418.32{\pm}32.03kg$, respectively. Meat quality grade was improved in HPHT (P<0.001), because the marbling score was highest in HPHT group. Auction prices (carcass/kg) of LPLT, LPHT and HPHT group were 17,904 won, 18,094 won and 18,899 won, respectively. The percentage of animals over grade 1 appeared in LPLT, LPHT and HPHT were 79.2, 72.7 and 90.8%, respectively. The results of chemical analysis of longissimus dorsi muscle showed no difference between groups but crude fat composition tended to be higher in HPHT group (P=0.088) than the other groups. Stearic acid contents in the muscle was significantly increased in HPHT group than LPLT group (P<0.05). Myristoleic acid and oleic acid composition in HPHT group was higher than LPLT and LPHT group. These results supported the hypothesis that supplementation of higher levels of crude protein and energy in concentrates to Hanwoo steers' during final fattening period improved the growth performance and the carcass quality grade.

• Resources Recycling
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• v.23 no.1
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• pp.40-47
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• 2014

Feasibility of utilizing unburned carbon residue in coal ash as a potential precursor for the production of activated carbon was assessed to seek for solution to recycle unburned carbon residue. The unburned carbon concentrate generated from the 4 stages of cleaner flotation has a grade of 87% carbon. The crystalline impurities in the concentrate included quartz and mullite. Unburned carbon had a low specific surface area of $10m^2/g$, which might be related to a high degree of coalification of domestic anthracite coal. Carbon particles were mostly porous and have a turbostratic structure. When 1g of carbon was activated with 6g of KOH powder, the highest specific surface area value of $670m^2/g$ was achieved. Low wettability of unburned carbon particles, which was resulted from high temperature combustion in a boiler, might cause poor pore formation when they were activated by KOH solution. The activated carbon produced in this study developed micropores, with an equivalent quality of general-purpose activated carbon made from coal. Hence, it is concluded that chemically treated unburned carbon can be used for water purification or an alternative to carbon black as it is.