• Resources Recycling
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• v.19 no.6
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• pp.36-42
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• 2010

Researches on resources recycling in the field of construction have made an extensive progress such as recycled aggregate of waste concrete and recycling of asphalt. On the other hand, there are almost never researches on pavement method with used waste frying oil. In South Korea, 0.2 million ton used waste frying oil is discharged every year. It is guessed that about 0.1 million ton used waste frying oil can be collected. If used waste frying oil is recycled, it is expected that disuse cost will be reduced and water pollution of rivers will be prevented. Therefore, the purpose of the study was to evaluate on mechanical features (strength, water resistance, chemical resistance, abrasion resistance, freezing and thawing resistance and permeable coefficient) whether dense graded permeable concrete mixing silica sand with flexible alkyd resin manufactured by making ester reaction with collected used waste frying oil to make alkyd resin could be applied to road pavement for non-roadway. The results of the study were as follows. In flexural strength, it had 1.6 times as much as road design standard 4.5MPa. In water resistance, chemistry resistance and freezing and thawing resistance, they had lack of strength in early age. As age went by, they didn't have large changes. And curing temperature had phenomenon of increase in strength at rather low temperature than high temperature by glass transition temperature of resin. Therefore, considering workability, strength and durability when it was applied to road pavement, it was reasonable that the mixing ratio of flexible alkyd resin was 10~15% in comparison with silica sand weight.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.39-39
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• 2007

원자층 증착(Atomic Layer Deposition: ALD) 방법은 반응물질들을 펄스형태로 챔버에 공급하여 기판표면에 반응물질의 표면 포화반응에 의한 화학적 흡착과 탈착을 이용한 박막증착기술이다. ALD법은 기존의 화학적 기상증착(Chemical Vapor Deposition: CVD)과 달리 자기 제한적 반응(self-limiting reaction) 에 의하여 반응가스가 기판 표면에서만 반응하고 가스와 가스 간에는 반응하지 않는다. 따라서 박막의 조성 정밀제어가 쉽고, 파티클 발생이 없으며, 대면적의 박막 증착시 균일성이 우수하고, 박막 두께의 정밀 조절이 용이한 장점이 있다. 이러한 ALD 방식으로 3차원의 반도체 장치 구조물에 산화막 등을 형성하는 공정에서 중요한 요소 중의 하나는 전구체의 충분한 공급이다. 따라서 증기압이 높은 전구체를 선호하는 경향이 있다. 그러나 증기압이 낮은 전구체를 사용할 경우, 공급량이 부족하여 단차 도포성(step coverage)이 떨어지는 문제가 있다. 원자층 증착 공정에서 전구체를 충분히 공급하기 위해전구체 온도를 증가시키거나 전구체의 공급시간을 늘리는 방법을 사용한다. 그러나 전구체 온도를 상승시키는 경우, 전구체의 변질이나 수명을 단축시키는 문제점을 발생시킬 수 있으며. 전구체를 충분히 공급하기 위하여 전구체의 공급시간을 늘이는 방법을 사용하면, 원하는 박막을 형성하기 위하여 소요되는 공정시간과 전구체 사용량이 증가된다. 본 논문에서는 이러한 문제점을 해결하기 위해 반응기 안에서 전구체 노출 시간을 조절하는 새로운 ALD 공정을 소개한다. 특히 이러한 기술을 적용하면 나노튜브를 성장시키는데 매우 유리하다. 본 연구에서 전구체 노출 시간을 조절하기 위하여 사용된 ALD 장비는 Lucida-D200-PL (NCD Technology사)이며 (TEMA)Zr와 H2O를 사용하여 ZrO2 나노튜브를 폴리카보네이트 위에 성장시켰다. 전구체의 노출 시간은 반응기의 Stop 밸브를 이용하여 조절하였으며, SEM, TEM 등을 이용하여 나노튜브의 균일성과 단차피복성 등의 특성을 관찰하였다. 그 결과 전구체 노출시간을 조절함으로써 높은 종횡비를 갖는 나노튜브를 성장 시킬 수 있음을 확인하였다. 또한 낮은 증기압을 가지는 전구체를 이용하여도 우수한 특성의 나노튜브를 균일하게 성장시킬 수 있었다.

• Polymer(Korea)
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• v.29 no.1
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• pp.74-80
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• 2005

To use the filter materials for reduction of carbonyl compounds in cigarette mainstream smoke, the bead type cation and anion exchangers were synthesized by the suspension polymerization of GMA and DVB followed by the subsequent functionalization with sodium sulfite and diethylamine, respectively. FT-IR/ATR was used to characterize functionalized copolymer formation by sulfonation and amination, and the morphology change of ion exchangers according to the adsorption of cigarette mainstream smoke were observed by SEM. Ion exchange capacity, functionalization yield and adsorption properties of carbonyl compounds in cigarette mainstream smoke were investigated. The highest functionalization yields and ion exchange capacity were obtained at 5 wt% DVB content in co-monomer. The adsorption amount of carbonyl compounds in cigarette mainstream smoke of anion exchanger was higher than that of cation exchanger because of its electron delocalization in carbonyl group. The adsorption efficiency was increased in the presence of moisture. This results indicated that the anion exchanger was applicable for cigarette filter material because of its large ion exchange capacity and rapid ion exchange reaction.

• Membrane Journal
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• v.22 no.1
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• pp.16-22
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• 2012

The influence of co-existing gases on the hydrogen permeation without sweep gas was studied through a Pd-coated $V_{99.8}B_{0.2}$ alloy membrane. Membranes have been investigated in the pressure range 1.5-8.0 bar under pure hydrogen, hydrogen-carbon dioxide and hydrogen-carbon monoxide gas mixture without sweep gas at $400^{\circ}C$. Preliminary hydrogen permeation experiments without sweep gas have been confirmed that hydrogen flux was $40.7mL/min/cm^2$ for a Pd-coated $V_{99.8}B_{0.2}$ alloy membrane (thick : 0.5 mm) using pure hydrogen as the feed gas. In addition, hydrogen flux was $21.4mL/min/cm^2$ for $V_{99.8}B_{0.2}$ alloy membrane using $H_2/CO_2$ as the feed gas. The hydrogen permeation flux decreased with decrease of hydrogen partial pressure irrespective of pressure when $H_2/CO_2$and $H_2/CO$mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert's law in different feed conditions. It was found from XRD, SEM/EDX results after permeation test that the Pd-coated $V_{99.8}B_{0.2}$ alloy membrane had good stability and durability for various mixtures feeding condition.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.1
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• pp.29-37
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• 2006

In remediation of the contaminated soil, it requires to select at least more than two remediation technologies depending on the fate and transport phenomena through complicated reactions in soil matrix. Therefore, methodologies related to develop the integrated remediation technology were reviewed for agricultural soils contaminated with heavy metals. Pneumatic fracturing is necessary to implement deficiency because soil washing is not effective to remove heavy metals in the subsurface soil. But it needs to evaluate the characteristics such as essential data and factors of designated technology in order to effectively apply them in the site. In the remediation site, the important soil physical and chemical factors to be considered are hydrology, porosity, soil texture and structure, types and concentrations of the contaminants, and fate and its transport properties. However, the integrated technology can be restrictive by advective flux in the area which remediation is highly effective although both soil washing and pneumatic fracturing were applied simultaneously in the site. Therefore, we need to understand flow pathways of the target contaminants in the subsurface soils, that includes kinetic desorption and flux, predictive simulation modeling, and complicated reaction in heterogenous soil.

• Journal of the Mineralogical Society of Korea
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• v.30 no.4
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• pp.179-186
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• 2017

This study investigated the mineralogical characteristics of lime mortars used in pointing of Namhansanseon Yeojang from Joseon dynasty. Polarization microscopy revealed quartz, feldspar, mica, pyroxene and opaque minerals in the lime mortars. XRD analysis also confirmed clay minerals chlorite and kaolin. As a result of particle size analysis of lime mortars, the particle size distribution was wide and size was not uniform. 60% of samples were corresponded to the sand area. The chemical components detected from XRF analysis, 8.71-11.18 % of Ca as the main component of lime and $SiO_2$, $Al_2O_3$, and $Fe_2O_3$ in soil minerals were main components. The lime mortars showed an endothermic peak due to decarbonization reaction of $CaCO_3$ at $750^{\circ}C$ and weight reduction rate of 10%. The microstructures were agglomerated amorphous and observed rhombohedral calcite crystals by scanning electron microscope. It is considered that the pointing of Yeojang is a mortar mixed with lime and soil. In addition the Hanbongseong Yeojang was constructed using the same materials and construction technique because the minerals composition is not different according to the Yeojang location and use.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.384-390
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• 2011

Ti-6Al-4V ELI (Extra Low Interstitial) alloy has been widely used as an alternative to bone due to its excellent biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity. Therefore, nontoxic biomaterials with a low elastic modulus should be developed. However, the fabrication of a uniform coating is challenging. Moreover, the coating layer on Ti and Ti alloy substrates can be peeled off after implantation. To overcome these problems, it is necessary to produce bulk Ti and Ti alloy with hydroxyapatite (HA) composites. In this study, Ti, Nb, and Zr powders, which are biocompatible elements, were milled in a mixing machine (24h) and by planetary mechanical ball milling (1h, 4h, and 6h), respectively. Ti-35%Nb-7%Zr and Ti-35%Nb-7%Zr-10%HA composites were fabricated by spark plasma sintering (SPS) at $1000^{\circ}C$ under 70MPa using mixed and milled powders. The effects of HA addition and milling time on the biocompatibility and physical and mechanical properties of the Ti-35%Nb-7%Zr-(10%HA) alloys have been investigated. $Ti_2O$, CaO, $CaTiO_3$, and $Ti_xP_y$ phases were formed by chemical reaction during sintering. Vickers hardness of the sintered composites increases with increased milling time and by the addition of HA. The biocompatibilty of the HA added Ti-Nb-Zr alloys was improved, but the sintering ability was decreased.

• ALGAE
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• v.35 no.1
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• pp.45-59
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• 2020

To investigate the spatio-temporal distributions of the mixotrophic dinoflagellate Yihiella yeosuensis in Korean coastal waters and its grazing impact on prey populations, water samples were seasonally collected from 28 stations in the East, West, and South Seas of Korea and Jeju Island from April 2015 to October 2018. The abundances of Y. yeosuensis in the water samples were quantified using quantitative real-time polymerase chain reaction (qPCR). Simultaneously, the physical and chemical properties of water from all sampled stations were determined, and the abundances of the optimal prey species of Y. yeosuensis, the prasinophyte Pyramimonas sp. and the cryptophyte Teleaulax amphioxeia, were quantified using qPCR. Y. yeosuensis has a wide distribution, as is reflected by the detection of Y. yeosuensis cells at 23 sampling stations; however, this distribution has a strong seasonality, which is indicated by its detection at 22 stations in summer but only one station in winter. The abundance of Y. yeosuensis was significantly and positively correlated with those of Pyramimonas sp. and T. amphioxeia, as well as with water temperature. The highest abundance of Y. yeosuensis was 48.5 cells mL^-1 in Buan in July 2017, when the abundances of Pyramimonas sp. and T. amphioxeia were 917.6 and 210.4 cells mL^-1, respectively. The growth rate of Y. yeosuensis on Pyramimonas sp., calculated by interpolating the growth rates at the same abundance, was 0.49 d^-1, which is 37% of the maximum growth rate of Y. yeosuensis on Pyramimonas sp. obtained in the laboratory. Therefore, the field abundance of Pyramimonas sp. obtained in the present study can support a moderate positive growth of Y. yeosuensis. The maximum grazing coefficient for Y. yeosuensis on the co-occurring Pyramimonas sp. was 0.42 d^-1, indicating that 35% of the Pyramimonas sp. population were consumed in 1 d. Therefore, the spatio-temporal distribution of Y. yeosuensis in Korean coastal waters may be affected by those of the optimal prey species and water temperature. Moreover, Y. yeosuensis may potentially have considerable grazing impacts on populations of Pyramimonas sp.

• Journal of Preventive Medicine and Public Health
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• v.35 no.4
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• pp.282-286
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• 2002

Objectives : The level of 4-hydroxyproline (4-Hyp) in human urine was measured using high performance liquid chromatography (HPLC) with a fluorescence detector. This method is useful for medical examinations and investigating the radicals induced by physical, chemical, mental stresses. This method is superior to many published several methods in terms of its low cost and ability to analyze many samples. Methods : The urine from workers in a tire manufacturing company (22 male pre- and post-shift workers) and 18 office-workers as controls were analyzed. Data concerning age, the cumulative drinking amount and the cumulative smoking amount was collected with a questionnaire. The optimum applied amount of dansyl-Cl, the optimum reaction temperature and time, the recoveries and the optimum pH of the eluent and buffer were determined.4-Hyp from human urine was derivatized with dansyl-Cl (dimethylamino-naphthalene-1-sulfonyl chloride) after removing the a-amino acid by a treatment with phthalic dicarboxaldehyde (OPA) and cleaned with Bond Elut C18 column. The 4-Hyp derivatives were separated on a reversed phase column by gradient elution with a phosphate buffer (5 mmol, pH 8.0) and acetonitrile, and detected by fluorescence measurements at 340 nm (excitation) and 538 nm (emission). Results : The detection limit for the urinary free 4-Hyp was $0.364{\mu}mol/l$. The recovery rate of 4-Hyp was 99.7%, and the effective pH of the phosphate buffer and borate buffer were 3.0 and 8.0, respectively. From statistical analysis, age, drinking and smoking did not affect the urinary free 4-Hyp in both the controls and workers. The range of urinary 4-Hyp in the controls, pre-shift, and post-shift workers were 0.33-16.44, N.D-49.06, and $0.32-56.27{\mu}mol/l$. From the pared-sample t-test, the urinary 4-Hyp levels in post-shift workers ($11.82{\pm}6.73\;nmmol/mg\;Cre$) were 2-fold higher than in pre-shift workers ($5.36{\pm}5.53\;nmol;/mg\;Cre$) and controls ($4.91{\pm}4.89\;nmol;/mg\;Cre$). Conclusions : This method was developed with high sensitivity, accuracy, and precision. The present method was effectively applied to analyze the urinary free 4-Hyp in both controls and workers.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.822-826
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• 2005

Colloidal Silica (CS)/methyltrimethoxysilane (MTMS) and CS/MTMS/epoxysilane (ES) sol solutions were prepared using various synthesizing parameters such as reaction time and types of CS and silane. In order to understand their physical and chemical properties, sol-gel coating films on glass were fabricated. In the case of the CS/MTMS sol, the coating films had high contact angle and more enhanced flat surface than the CS/MTMS/ES sol. In the case of thermal stability, thermal degradation of the CS/MTMS and CS/MTMS/ES coating films did not occur up to $550^{\circ}C$ and $440^{\circ}C$, respectively. The coating films prepared from the CS/MTMS sol were thicker than those of the CS/MTMS/ES sol. In addition, the coating films prepared from single CS were thicker than those of mixed CS. Hardness of the coating films prepared from CS/MTMS increased by adding ES. In case of the mixed CS, the hardness decreased by adding ES.