• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.210-218
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• 2018

Ethylenediaminetetraacetic acid (EDTA)-functionalized KIT-6 and KCC-1 mesoporous silicas were prepared via post-synthesis grafting and examined for their ability to promote the recovery of rare earth metal ions such as $Nd^{3+}$ from an aqueous medium. The obtained adsorption isotherms were fitted to the Langmuir model, which gave a maximum adsorption of $Nd^{3+}$ ions of 109.8 and 96.5 mg/g for KIT-6-EDTA and KCC-1-EDTA, respectively, at $25^{\circ}C$ and pH 6. The adsorption kinetic profile of KIT-6 was faster than KCC-1. KIT-6 was also proved to be more stable against desorption under acidic regeneration conditions.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.232-236
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• 2006

The Y1.99-xMxCe0.01SiO5(M=Li, La, Nd, and Gd) phosphors were synthesized by solid-state reaction at 1350oC for 10h under reducing atmosphere in order to improve properties of blue emitting phosphors. Compared with commercial blue phosphors, the Y2SiO5:Ce blue phosphors substituted with various elements showed significant enhancement of the emission intensity. Particularly, 1 mol% Li doped Y2SiO5:Ce phosphors indicated the maximum emission intensity in the photoluminescence spectra. Thanks to SEM analyses revealed that the morphology of Y2SiO5:(Ce,Li) blue phosphors was a pseudo-spherical with particle size of 3m.

• Journal of the Korean Society of Earth Science Education
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• v.3 no.1
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• pp.28-35
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• 2010

This study is aiming to determine the effect of learning dimensions oriented elementary science lecture on scientific attitude, academic achievement, and logical thinking based on 'Earth' section in the 2nd semester of the 5th grade. Analyzing sub-categories of dimension in each lecture before teaching, a teaching and a learning plans based on dimension 3 and 4 were devised and applied. The result of this study is as follows: Firstly, when sub-categories of Earth section in the 2nd semester of the 5th grade in elementary schools were examined, the unit '5-2-4. Volcanoes and Rocks' was missing 8 of total 28 sub-units, while '5-2-7. Solar families' unit was covering all sub-units of every learning dimension. Secondly, learning dimensions 3 and 4 centered elementary school teaching caused significant difference in scientific attitude. Especially, among other sub-categories of scientific attitudes, 'Social meaning of Science', 'Attitude toward Science lessons' were better improved. Thirdly, learning dimensions 3 and 4 based elementary school lectures didn't bring significant difference to academic achievement. Fourthly, learning dimensions 3 and 4 oriented elementary lessons didn't imply significant difference in sub-logics of logical thinking, however proved to be helpful for students of transitional age.

• Korean Journal of Veterinary Service
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• v.24 no.4
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• pp.379-382
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• 2001

To confirm the effect of food and water deprivation prior to Newcastle disease(ND) virus vaccination, three hundred chicks were divided into five groups with three replications. ND vaccine were sprayed to at 1 -day old chicks at commercial hatchery. Secondary and third vaccination was conducted at 2-week old and 24-day old chicks by LaSota strain. Control was conventionally vaccinated without withdrawing the food and water before or after vaccination. In group 2(G2) and 3(G3), LaSota strain was vaccinated to chicks before and after fasting the food and water for 3 and 2 hours, respectively. Group 4(G4) has the same fasting time of group 2, but supplemented the skim milk in vaccin dilution water. In group 5(G5), skim milk was added into group 3. Weight gain, feed intake and feed conversion were weekly measured for 5 weeks. Blood was collected from wing vein at 24 and 35 days of age. Each serum antibody level were measured by hemagglutination inhibition(HI) test. The average weight gain, feed intake, feed conversion of all group were not significantly different. Weight gain of each groups was 1910.30(control), 1875.28(G2), 1952.12(G4) and 1896.05(G5), respectively. Feed intake of all group was recorded at 3160.67(control), 3167.07(G2), 3189.48(G3), 3157.85(G4) and 3178.16(G5), respectively. The feed conversion of each groups was 1.655(control), 1.688(G2), 1.633(G3), 1.699(G4) and 1.676(G5), respectively. The HI titer of G4 was $ 5.50{\Pm}$1.40 and significantly higher than the other groups (p<0.05)(control : $4.36{\Pm}$1.87 , G2 : $5.18{\Pm}$2.14, G3 : $4.51{\Pm}$2.19, G : $5.28{\Pm}$1.58 at 35 days old. The results of this experiment indicated that two or three hours of fasting time before or after vaccination would be able to show the higher antibody level against ND virus.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1849-1851
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• 1999

The PDP(Plasma Display Panel) barrier rib was fabricated by focused $Ar^+$ laser ($\lambda$=514nm) and Nd:YAG($\lambda$=532, 266 nm) laser irradiation. The depth of the etched groove increases with increasing a laser fluence. and decreasing a scan speed. Using the second harmonic of the Nd:YAG laser, the threshold laser fluence was $6.5mJ/cm^2$ for the sample of PDP barrier rib dried at $120^{\circ}C$. The thickness of $150{\mu}m$ of the sample on the glass was etched without any damage on the glass substrate by fluence of $19.5J/cm^2$. The barrier rib sample on hot plate was etched by Nd:YAG laser(532 nm) as increasing a temperature of the sample. In this case, the etch rate was $95{\mu}m/s$, $190{\mu}m/s$ at room temperature, $175^{\circ}C$ respectively.

• Journal of Welding and Joining
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• v.27 no.5
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• pp.55-61
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• 2009

Pure titanium and its alloys have good formability, excellent corrosion resistance and high strength to weight ratios. Therefore, it has been using to heat exchangers, offshore plants, sports equipments, and etc. As broad as its application fields, it also increases welding locations. Conventional GTAW and GMAW are very popular welding methods of titanium, but it has a high heat input and wide HAZ. It has a possibility of inducing Stress Corrosion Cracking. So, laser welding method has been using to get reliable welds by reducing heat input. Weld beads change its color to silver, gold, brown, blue, and gray by shied conditions. And the closer to gray, the more oxidize, nitride and embrittlement. The most effective atom to embrittlement was nitrogen. And shield gas flow was not so effective over the constant flow rates. In this study, weld properties of the pure titanium were investigated by pulsed & CW Nd:YAG lasers and evaluated by various shield conditions. And It is observed that nitrogen is more effective to oxidation and embrittlement of titanium compared with oxygen by oxygen and nitrogen quantitative analysis.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.71-71
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• 2003

최근 통신용 전자부품의 소형화, 저가격화, 고기능화의 요구가 점점 더 증대되고 있으며 이를 위해서 기판의 배선밀도를 높이는 것과 개별 부품 또는 모듈의 크기와 무게를 줄이는 것이 절실히 필요하다. 본 연구에서는 저융점의 phosphate계 유리 프릿의 첨가를 통해 LTCC (Low Temperature Co-fired Ceramic) 에 적용 가능한 조성을 개발하고자 하였다. 마이크로파 용 유전재료로서 널리 사용되고있는 BNT (BaO-Nd$_2$O$_3$-TiO$_3$) 계 세라믹스에 저융점 유리 프릿의 양을 10-30wt% 범위로 변화시키면서 900-110$0^{\circ}C$ 범위에서 소결하여 이에 따른 수축률 변화와 상대밀도의 변화를 조사하였다 유리 프릿으로 P$_2$O$_{5}$-ZnO-BaO-Nd$_2$O$_3$ 계, P$_2$O$_{5}$-SnO-ZnO 계 2가지 조성의 유리를 사용하였다 그 결과로 소결체의 상대밀도는 소성온도가 900-110$0^{\circ}C$ 로 증가함에 따라 85-96% 로 증가하였고, 그 수축률은 소결온도 100$0^{\circ}C$ 에서 급격히 증가하였다. 이러한 결과는 저온 동시소성 세라믹 조성의 사용을 위해 좋은 결과가 예상된다.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.35-40
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• 2013

Recently reclamation land is largely developed to utilize the land according to economic growth. The soil of landfill is soft, low shear strength, which makes it difficult to use the equipment. A large movement is occurred on the utility tunnel under construction. The inclined land with high water level and underground facilities are widely distributed and the excess pore water pressure may occur under construction similarly to this study. Some different conditions are made to design result, such as 4m of soil piling near the construction area, heavy rainfall during 2nd excavation that may cause flow liquefaction. To analyze the cause of transverse lateral movement, Three dimensional analysis are performed to four load cases, which is original design condition, flow liquefaction by heavy rainfall, unsymmetric lateral soil pressure, and both of them simultaneously. Ten steps of full construction stage, 1st excavation for utility tunnel, construction of utility tunnel, 1st refill, piling soil from 1m to 4 m, 2nd excavation for drainage culvert, liquefaction around the utility tunnel, construction of drainage culvert and 2nd refill, are take into account to investigate the cause of movement.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.259-264
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• 1993

Ion chromatographic method has been applied for burnup measurement of irradiated nuclear fuel by dynamic system using 1-octanesulfonate as a cation exchanger and $\alpha$-hydroxyisobutyric acid as an eluant. A number of elution techniques were evaluated for the optimum separation of plutonium, uranium and neodymium. These elements were individually separated and collected by gradient elution between 0.05 M and 0.40 M of $\alpha$-hydroxyisobutyric acid in a single column, and finally determined by isotope dilution mass spectrometry. The burnup data from this method were compared with those from conventional anion exchange method. The results showed a good agreement within 3.5 % of difference between two methods.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.398-402
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• 1975

The light scattering studies of the aqueous solution of dodecyl pyridinium chloride (DPC) and tetradecyl pyridinium chloride (TPC) over the concentration range of 0~70 mM revealed that there exists a so-called 2nd critical micelle concentration (cmc) at about 43 mM and 8 mM respectively in addition to their 1st cmc at 17 mM and 3.5 mM. The 2nd cmc was greatly influenced by additives KCl, which lowered the 2nd cmc. The micelle molecular weight of DPC and TPC solutions at 1st cmc were 20800 and 15600 and the degree of ionization of their micelles at 1st cmc were 0.092 and 0.226 respectively.