• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.144-152
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• 2016

This paper focuses on the experimental study for investigating the performance for lap splice of hooked or headed reinforcement in beam with different depths. In the experiment, seven specimens, with its variables as the lap length of headed or hooked bar, the existence of stirrups, etc., was manufactured. Bending test was conducted. Lap strengths by test were compared with the theoretical model based on KCI2012. The result showed that the cracks at failure mode occurred along the axial direction to a headed bar. The initial stiffness and the stiffness after initial crack were similar for all specimens. For HS series specimens without stirrups, a 25% increase in lap length was increased 11.8~18.1% maximum strengths. For HH series specimens without stirrups, a increase in lap length did not affect the maximum strengths because of the pryout failure of headed bar. For HS series specimens, the theoretical lap strengths based on KCI2012 considering the B grade lap and the reduction factor for stirrup were evaluated. They are smaller than the test strengths and can ensure the safety in terms of strength capacity. For HH series specimens, the stirrups in the lap zone are needed to prevent the pryout behaviour of headed bar.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.1-8
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• 2018

FRP is a new material that is light, has high strength and high durability, and is emerging as a third construction material inside and outside of countries. However, very few studies have been done on curved FRP construction materials that can be used for tunnels or arched bridges. Because a small composite panel specimen is smaller than a full-size specimen, it can be used in a variety of experiments under different conditions. Therefore, in this study, experiments were performed on a void section, a solid section, a connected solid section, and a sand-coating solid section. The results of the experiment show that the connection of composite curved panels with longitudinal connections provides almost equivalent performance to that of a single panel. However, it is necessary to strengthen the connections, since the connections that are most susceptible to damage will break first.

• The Journal of Engineering Research
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• v.6 no.2
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• pp.23-32
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• 2004

Metals, ceramics and polymers are widely used as bioimplant materials. However, Ti and Ti alloys are widely used because of its high strength to weight ratio and good biocompatibility when implanted in the body. In this experiment, Ti alloys of Grade-4 (gr4), 0.2 wt % Fe, 0.5 wt % Fe and 2 wt % Fe were studied for their surface morphology and HAp forming ability on the metal substrate for different treatments. Intially, the samples were mechanically polished on silicone carbide paper (No.-2000). The polished samples were treated with 5M NaOH solution at $60^{\circ}C$ for 24 hours. The NaOH treated samples were washed gently with distill water and dried at $40^{\circ}C$ for 1 day. The dried samples were heated in air at $600^{\circ}C$ for 1 hour. The surface morphology of these samples were studied using SEM. The SEM studies showed network of pores in all samples. These samples were immersed in stimulated body fluids (SBF) kept at $36.5^{\circ}C$ for different periods over the length of 1 to 14 days. The apatite formation was confirmed on all Ti-alloys using EDAX.

• Korean Journal of Poultry Science
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• v.29 no.2
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• pp.117-124
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• 2002

Betaine functions as an osmoregulators in the cells and its inclusion in diet can spare the choline and carcass fat reduction in chicken. Thus, two hundred eighty eight laying hens were fed with 0, 500, 1,000, 2,000 ppm of betaine from seventy eight to eighty six weeks of age during the environmentally high temperature stress. Com and soybean basal diets contained 2,800 kcal/kg ME and 16% CP. Egg production, feed intake, and feed conversion were examined for eight weeks. Egg quality characters, serum cholesterol, liver betaine, and lower ileal osmolality were measured at the end of experiment. Egg Production rates of hens fed with 500 or 2,000 ppm of betaine were 75.06 and 75.02%, respectively and tended to increase compared to the control. The feed conversion(FCR) of these treatments was significantly(P<0.05) improved compared to that of control although it did not significantly differ in the e99 Production rates between 500 and 2,000 ppm of betain groups. Eggshell breaking strength of hens fed betaine was significantly(P<0.05) higher than those of control. However, betaine supplements did not influence to improving the albumen height and Haugh unit. Liver betaine in hens fed with betaine was linearly increased unto 2,000 ppm. The birds fed with 2,000 ppm betaine showed significantly(P<0.05) higher in the liver betaine than the control birds. Total cholesterol and triglyceride tended to be increased by dietary betaine supplement. The lower ileal osmolality in betaine supplement group tended to be slightly decreased. As a result, dietary betaine supplement tended to improve the egg Production and eggshell Quality in laying hens during heat stress.

• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.73-81
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• 2003

This experiment was conducted to investigate the effects of dietary energy and protein levels on the growth rate of egg breeder pullets. A total of 360 Hy-Line Brown pullets aged 2 to 6 weeks (Phase I) were fed 5 rations differing in dietary protein (17, 19 and 20%) and energy (2,800, 2,950 and 3,050 kcal/kg, TMEn) leveIs for a period of 5 weeks and those aged 6 to 10 weeks (Phase II) were fed 5 rations differing in dietary protein (15, 16 and 17%) and energy (2,800, 2,900 and 3,000 kcal/kg, TMEn) levels in order to evaluate the optimum dietary energy and protein leveIs for egg breeder pullets reared in cages. Their body weight gains were significantly influenced by the dietary protein levels (P<0.05). The dietary energy levels did not greatly affect the growth performances throughout the experimental period. The low energy and protein regimen based on NRC requirement (control) was found to produce smaller pullets and lower tibia bone measurements as compared to the higher regimen groups. With the increase in dietary energy and protein levels, tibial bone strength and ash content also gradually increased (P<0.05). There were no significant differences in the flock uniformity among the treatments. These results indicate that increases in dietary energy and protein levels above the NRC requirements appeared to be more effective in obtaining the optimal growth and bone developments of egg breeder pullets reared in cage.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.238-246
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• 2005

We conducted this investigation to observe competitive adsorption phenomena among the heavy metals onto the available sorption sites of soil particle surfaces in sandy clay loam and clay soil collected from Nonsan city, Chungnam and Yoosung, Daejeon in Korea, respectively. Polluted and contaminated soils can often contain more than one heavy metal species, resulting in competition for available sorption sites among heavy metals in soils due to complex competitive ion exchange and specific sorption mechanism. And the adsorption characteristics of the heavy metals were reported that the selectivity for the sorption sites was closely related with electropotential and electro negativity carried by the heavy metals. The heavy metals were treated as single, binary and ternary systems as bulk solution phase. Adsorption in multi-element system was different from single-element system as Cr, Pb and Cd. The adsorption isotherms showed the adsorption was increased with increasing equilibrium concentrations. For binary and ternary systems, the amount of adsorption at the same equilibrium concentration was influenced by the concentration of individual ionic species and valence carried by the respective heavy metal. Also we found that the adsorption isotherms of Cd and Pb selected in this experiment were closely related with electronegativity and ionic potential regardless number of heavy metals in solution, while the adsorption of Cr carried higher valance and lower electro negativity than Cd and Pb was higher than those of Cd and Pb, indicating that adsorption of Cr was influenced by ionic potential than by electronegativity. Therefore adsorption in multi-element system could be influenced by electronegativity and ionic potential and valance for the same valance metals and different valance, respectively. But it still needs further investigation with respect to ionic strength and activity in multi-element system to verify sorption characteristics and reaction processes of Cr, especially for ternary system in soils.

• Journal of Plant Biotechnology
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• v.29 no.1
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• pp.19-23
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• 2002

This experiment was conducted to micropropagate bulblets via shoot cluster formation and massproduce normal bulblets from the sections of proliferated shoot clusters in Lilium asiatic hybrid 'Hae Hwa'. The induction of shoot clusters from the culture of bulblet sections was more effective than that of bulb scales on MS medium with 1.0 mg/L BA and 0.5 mg/L IAA. Proliferation of shoot clusters from the formed shoot cluster sections was the most favorable on medium containing 5.0 mg/L BA and 0.5 mg/L IAA. The formation and the growth of bulblets from shoot cluster sections were achieved effectively on medium with 60∼90 g/L sucrose. The leaves derived from shoot clusters grew vigorously but the bulblets from shoot clusters grew very poor in 5L air-lift bioreactor culture. By the addition of 30 mL fresh liquid medium containing doulble strength MS salts, 250 g/L sucrose and 5 g/L activated charcoal after 8 weeks in the shoot cluster culture on MS medium with 5.0 mg/L BA and 0.5 mg/L IAA, the number of bulblets was increased in light condition, but the growth of bulblets was not affected by light. Bulblet production was possible with the bulblet product at 53 to 68 mg in fresh weight by liquid medium addition after the proliferation of shoot cluster.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.800-808
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• 2005

The compounding resin for biodegradable wrap was developed, and its manufacturing process and physical properties were studied. For these purposes, following factors were optimized: the types and amounts of raw resin material, anti-oxidants, and lubricants used. In this work, the stable compounding resin used to make biodegradable wrap was based on poly(butylene adipate-co-butylenesuccinate) (PBAS) and poly(butyleneadipate-co-butylene succinate-co-butyleneterephthalate) (PBAST). The improved properties of resin with an additive were investigated by melting flow index (MFI). From these results, the physical properties of compounding resin, based on PBAST, were more than those of PBAS. For PBAS, the Irganox 1010, 1076 and Irgafos TNPP as the first and second anti-oxidants, respectively, were good. For PBAST, the good first and second anti-oxidants, respectively, were Irganox 1076 and Mark PEP 36. The good lubricants for feeding PBAS and PBAST were glycerol monostearate and palmityl alcohol, respectively. The stability and tensile strength experiment of wrap were also investigated by the elution of heavy metals and universal testing machine (UTM), respectively. The decomposition ratio of developed wrap was increased proportional to the reclaiming time. The degradation ratio of compounding resin sample was about 60% after 40 days.

• Resources Recycling
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• v.4 no.1
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• pp.12-19
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• 1995

This study was carried out to remove the iron and impurities usmg hydrocyclone and HGMS for recycling of sludge from the granite stone cutting and polishing industrγ in the basic of chemi떠1 analysis and minerallogical investigation. This sludge consist of 70.9% $SiO_2$ 13.6% $Al_2O_3$ and It also contained 2.52% of $Fe_2O_7$ and 0.29% of $TiO_2$, as a main impurities to decrease the whiteness. As the result of hydrocyclone experiment, It was very good condition that are 100~150 g/l of sludge amount, 2.0~ 2.5 mm of underflow nozzle size, and 1.2~1.6 kg/$\textrm{cm}^2$ of pressure for 85% sludge product with the $-37{\mu}\textrm{m}$ size. $Fe_2O_3$ and $TiO_2$, contents by treatment of HGMS were decreased with 0.65% and 0.07% each at 10,000 gauss of magnetic field strength, and addih$\upsilon$n of Sodium tripolyphosphate as a dispersant was effected to get low grade F Fe,Ol and TiO, concentrate. PhYSIcal properties of this stone sludge product were showed 58.5% of whiteness, 1 13.4% of firing shrinkage and 3.0812 $\textrm{m}^2$/g of specific surface area.

• Journal of Korean Society of Forest Science
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• v.79 no.4
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• pp.419-423
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• 1990

This study was carried out to investigate the cause of pith-damaged wood formation, the state of growth, and difference of chemical composition of Japanese Larix(L. leptolepis Gorden). 1. Larix grew normaly to 10 years, and the volume increment was 32.4%. But it was gradually decreased to 19.4% from 11 to 13 years that the heartwood damage was occurred. Therefore, the volume increment was decreased 13%. The decayed wood was formed from fire wound portion of bark by forest fire. The volume loss from pith-dagmaged wood occurred by forest fire was more than 20%. 2. On the ash content, heartwood(0.05%) and pith-damaged wood(0.08%) was lower than sapwood(0.29%). The difference of extractive contents are considered the reason. It is considered that this ash content difference is depend upon the extractive contents among sap, heart and decayed wood parts. Holocellulose contents were from 54.3% to 59.3% and there were no difference among heartwood, pith-damaged wood, and sapwood, On the pentosan contents, heartwood(6.3%) and pith-damaged wood(6.6%) were higher than sapwood. Lignin contents of pith-damaged wood was tower than heartwood (34.4%). This seems to weaken all kinds of wood strength.