• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.41-47
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• 2003

For the development of low temperature anode-supported planar solid oxide fuel cell, the planar anode supports with the thickness of 0.8 to 1 mm and the area of 25, 100 and $150\;cm^2$ were fabricated by the tape casting method. The strength, porosity, gas permeability and electrical conductivity of the planar anode support were measured. The porosity of anode supports sintered at $1400^{\circ}C$ and then reduced in$H_2$ atmosphere was increased from $45.8\%\;to\;53.9\%$. The electrical conductivity of the anode support was $900 S/cm\;at\; 850^{\circ}C$ and its gas permeability was 6l/min at 1 atm in air atmosphere. The electrolyte layer and cathode layer were fabricated by slurry dip coating method and then had examined the thickness of $10{\mu}m$ and the gas permeability of 2.5 ml/min at 3 atm in air atmosphere. As preliminary experiment, cathode multi-layered structure consists of LSM-YSZ/LSM/LSCF. At single cell test using the electrolyte layer with thickness of 20 to $30{\mu}m$, we achieved $300\;mA/cm^2$ and 0.6V at $750^{\circ}C$

• Membrane Journal
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• v.19 no.4
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• pp.317-323
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• 2009

In this study the nanofiltration (NF) membrane treatment of a nitric acid waste solutions containing $Pb^{+2}$ heavy metal ion discharging from the etching processes of an electronics and semiconductors industry has been studied for the purpose of recycling of nitric acid etching solutions. Three kinds of NF membranes (General Electric Co. Duraslick NF-4040 membrane, Dow Co. Filmtec LP-4040 membrane and Koch Co. SelRO MPS-34 4040 membrane) were tested for their separation efficiency (total rejection) of $Pb^{+2}$ ion and membrane stability in nitric acid solution. NF experiments were carried out with a dead-end membrane filtration laboratory system. The membrane permeate flux was increased with the increasing storage time in nitric acid solution and lowering pH of acid solution because of the enhancing of NF membrane damage by nitric acid. The membrane stability in nitric acid solution was more superior in the order of Filmtec LP-4040 < Duraslick NF-4040 < SelRO MPS-34 4040 membrane. The total rejection of Pb+2 ion was decreased with the increasing storage time in nitric acid solution and lowering the pH of acid solution. The total rejection of $Pb^{+2}$ ion after 4 months NF treatment was decreased from 95% initial value to 20% in the case of Duraslick NF-4040 membrane, from 85% initial value to 65% in the case of SelRO MPS-34 4040 membrane and from 90% initial value to 10% in the case of Filmtec LP-4040 membrane. These results showed that SelRO MPS-34 4040 NF membrane was more suitable for the treatment of an acidic etching waste solutions containing heavy metal ions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.4
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• pp.158-163
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• 2011

$CuInS_2$ thin films were prepared using a sol-gel spin-coating method. That makes large scale substrate coating, simple equipment, easy composition control available. The structural and optical properties of $CuInS_2$ thin films that include less toxic materials (S) instead of Se, tetragonal chalcopyrite structure. Copper acetate monohydrate ($Cu(CH_3COO)_2{\cdot}H2O$) and indium acetate ($In(CH_3COO)_3$) were dissolved into 2-propanol and l-propanol, respectively. The two solutions were mixed into a starting solution. The solution was dropped onto glass substrate, rotated at 3000 rpm, and dried at $300^{\circ}C$ for Cu-In as-grown films. The as-grown films were sulfurized inside a graphite container box and chalcopyrite phase of $CuInS_2$ was observed. To determine the optical properties measured optical transmittance of visible light region (380~770 nm) were less than 30 % in the overall. The XRD pattern shows that main peak was observed at Cu/In ratio 1.0 and its orientation was (112). As annealing temperature increases, the intensity of (112) plane increases. The unit cell constant are a = 5.5032 and c = 11.1064 $\AA$, and this was well matched with JCPDS card. The optical transmittance of visible region was below than 30 %.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.457-460
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• 2005

Nano-sized titanium oxide and zirconium oxide powders were synthesized by hydrolysis of titanium isopropoxide $[Ti(OC_3H7)_4]$ and zirconium tetrachloride ($ZrC1_4$) via a sol-gel technique. Lead titanate powders were prepared by mixing $TiO_2$ precursors with PbO slurry made with dilute $NH_4OH$. Lead zirconate titanate powders were, then, synthesized by mixing $PbTiO_3$ with $ZrO_2$ powders. The goal of this research was to obtain the $PbZrTiO_3(PZT)$ powders and sintering these powders at low temperature. The $PbTiO_3$ and PZT powders after firing were analyzed by X-ray diffraction(XRD) and transmission electron microscopy(TEM) was utilized to observe the shape and size of the synthesized nano-particles. In the XRD pattern, the well-crystallized PZT phase could be obtained in consequence of firing at $900^{\circ}C$. SEM micrographs also showed that grains of PZT were relatively well grown with the size of the range of $2{\~}4{\mu}m$. The densified perovskite structure of $PbZrTiO_3$ could be obtained by sintering at temperature as low as $900^{\circ}C$. Characterization of the samples showed improved piezoelectric properties.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.22-27
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• 2017

$TiO_2$ films, thickness of $1{\sim}30{\mu}m$ were deposited on glass substrate at room temperature by room temperature granule spray in vacuum. The starting powder was calcinated at $600^{\circ}C$ for 4 h using $Al_2O_3$ crucible in the furnace. The particle size of the $TiO_2$, $1.5{\mu}m$ was measured by a particle size analyzer. The effect of different process parameters such as number of pass, gas flow rate and feeder voltage was studied. As the number of passes increased, the film thickness increased proportionally due to adequate kinetic energy conserved. The effect of three different flow rates (i.e. 15, 25, and 35 LPM) on deposited film was investigated. As gas flow rate increased, the film thickness increased up to 25 LPM and then decreased. Higher feeder voltage with low flow rate of 15 LPM resulted in unsufficient coating thickness due to insufficient kinetic energy. Microstructure of $TiO_2$ films was investigated by scanning electron microscope and high resolution tramission electron microscope.

• Membrane Journal
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• v.28 no.3
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• pp.214-219
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• 2018

In the present study, superflux nickel capillary supports for gas and vapor separation membranes were prepared by a combined process of NIPS and sintering. Nickel capillary precursors were prepared by NIPS process from PSf-Ni-DMAC-PEG400 dope solution and was sintered at various temperatures in $H_2$ atmosphere to reliably produce Ni capillary support. The optimized Ni capillary support has an outer and inner diameters of 722 and $550{\mu}m$, and its thickness was $94{\mu}m$. It has 3-dimensional pore channel network and its porosity and mean pore diameter was 26% and $4{\mu}m$, respectively. Also, its mechanical strength was tested in tensile mode: its fracture load was 2.84 kgf and the fracture elongation was 13%. Finally, its single gas permeance was measured: He, $N_2$, $O_2$, and $CO_2$ permeance was 432,327, 281,119, 264,259, and 193,143 GPU, respectively. The superflux behavior could be explained from viscous flow through the macropores having a diameter of $4{\mu}m$ and narrow thickness. It could be concluded that the superflux behavior of the Ni capillary support was from the 3-D pore channel network and the small thickness.

• Restorative Dentistry and Endodontics
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• v.36 no.4
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• pp.290-299
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• 2011

Objectives: The usage of fluoride varnish for a moderate to low caries-risk group has not been well validated. This study aimed to evaluate the preventive and therapeutic efficacies of fluoride varnish on the initiated root caries. Materials and Methods: Ten premolars were sectioned into quarters, further divided into two windows, one of which was painted with Fluor Protector (1,000 ppm fluoride, Ivoclar Vivadent). An initial lesion with a well-preserved surface layer was produced by pH cycling. Scanned line analysis using energy dispersive spectrometry determined the weight percentages of Ca and P in the demineralized layer. Scanning Electron microscopy and confocal laser scanning microscopy (CLSM) evaluated the varnish-applied root surfaces. Results: The mean lesion depth (SD) was 12.3 (2.6) ${\mu}m$ (single cycling) and 19.6 (3.8) ${\mu}m$ (double cycling). Double cycling extended the lesion depth, but induced no more mineral loss than single cycling (p < 0.05). The mean weight percentages of Ca and P between groups with and without varnish were not significantly different (p < 0.05). A CLSM showed varnish remained within 15 ${\mu}m$ of the surface layer. Conclusions: When a mild acid challenge initiated root tissue demineralization, the application of low-concentration fluoride varnish did not influence the lesion depth or the mineral composition of the subsurface lesion.

• Journal of Pharmaceutical Investigation
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• v.29 no.1
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• pp.29-36
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• 1999

Aceclofenac is an non-steroidal antiinflammatory drug which has been used in the treatment of rheumatoidal rthritis and osteo-arthritis. In order to decrease the gastric ulcerogenic effects and contol the plasma level of aceclofenac, we have developed the transdermal delivery system of aceclofenac plaster, which were formulated employing matrix polymers of acrylates and penetration-enhancers such as $Lauroglycol^{\circledR}$, $Transcutol^{\circledR}$, oleic acid and linoleic acid. Using Franz diffusion cells mounted with a rat skin, transdermal penetration characteristics of the formulations were evaluated by the HPLC assay of aceclofenac and diclofenac, an active metabolite, in the receptor compartment of pH 7.2 phosphate buffered solution. Skin penetration was increased when the content of aceclofenac increased, showing the flux $(J,\;{\mu}g/cm^2/hr)$ of 0.37 and 2.50 for 2% and 6.75% of the content, respectively. The flux$(J,\;{\mu}g/cm^2/hr)$ from plasters made of $Durotak^{\circledR}$ 87-2074, $Durotak^{\circledR}$ 87-2510 and $Durotak^{\circledR}$ 87-2097 were 2.50, 2.77 and 4.39, respectively. $Durotak^{\circledR}$ 87-2074 showed the lowest penetration due to the carboxylic acid group in the polymer, which might form a strong hydrogen bonding with a secondary amine of aceclofenac. Although both $Durotak^{\circledR}$ 87-2510 and $Durotak^{\circledR}$ 87-2097 are amine-resistant adhesives, $Durotak^{\circledR}$ 872510 showed lower penetration than $Durotak^{\circledR}$ 87-2097 because of the hydroxyl group in $Durotak^{\circledR}$ 87-2510, which might form a weak hydrogen bonding with aceclofenac. These results reveal that the functional group in acrylic polymers would greatly affect the release of aceclofenac from the matrix, which is the rate-limiting step in the penetration of aceclofenac through rat skins. The penetration of aceclofenac from plasters using different penetration-enhancers increased in the following order: Transcutol < linoleic acid < oleic acid. And the flux from the plasters containing oleic acid as a penetrationenhancer was 2.22 times greater than that of creams, which suggest that a newly deveolped aceclofenac plaster could be used in the treatment of rheumatoidal arthritis and osteo-arthritis as an advanced transdermal delivery system.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.171-182
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• 1990

The purpose of this study was to investigate the effects of irradiation on the striated duct cells of the rat submandibular gland ductal tissues which control the characteristics of saliva. For this study, the experimental group was composed of 36 irradiated Sprague Dawley strain rats divided into 8 subgroups 1 hour, 2 hours, 3 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours after irradiation. 4 non-irradiated rats were used as the control group. The experimental animals were singly irradiated with a dose of 18Gy gamma ray to their head and neck region by the Co-6- teletherapy unit and sacrificed after each experimental duration. The specimens were examined with a light microscope with an H-E stain and with a trans- mission electron microscope. The results of this study were as follows. In the light micrograph, a severe atrophic change occurred in the striated duct cells at 2hours after irradiation and gradual recovery occurred from 6 hours after irradiation. 2. The nuclear chromosomes of the striated duct cells were changed granular at 2 hours after irradiation. Recovery was observed at 6 hours after irradiation. Nuclear bodies were also observed from 3 hours after irradiation. 3. The mitochondria of the striated duct cells had indistinct cristae at 2 hours after irradiation, and were degenerated or swollen at 3 hours after irradiation. They recovered, however, from 6 hours, with an increasing number at 48 hours and a regular arrangement was observed at 72 hours after irradiation. 4. The microvilli showed atrophic changes at 2 hours after irradiation and were almost lost at 3 hours after irradiation. They were observed again from 48 hours after irradiation. 5. The rough endoplasmic reticulum and golgi body were not apparent at 1 hour after irradiation and were dilated with degeneration 2 hours after, but intact rough endoplasmic reticulum were observed from 3 hours after irradiation and developed well at 24 hours after irradiation. By the result of this study, showing a mild change in the functional morphology of the salivary striated duct cells immediately following irradiation, it is considered that the many complications which occur after radiation therapy, will disappear in time with the histological and the functional recovery of the glandular tissues.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.83-83
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• 2012

금속 실리사이드는 낮은 비저항, 실리콘과의 좋은 호환성 등으로 배선 contact 물질로 널리 연구되고 있다. 특히 $CoSi_2$는 선폭의 축소와 관계없이 일정하고 낮은 비저항과 열적 안정성이 우수한 특성 등으로 배선 contact 물질로 활발히 연구되고 있다. 금속 실리사이드를 실리콘 평면기판에 형성시키는 방법으로는 열처리를 통한 금속박막과 실리콘 기판 사이에 확산작용을 이용한 SALICIDE (self-algined silicide) 기술이 대표적이며 CoSi2도 이와 같은 방법으로 형성할 수 있다. Co 박막을 증착하는 방법에는 물리적 기상증착법 (PVD)과 유기금속 화학 증착법 등이 보고되어있지만 최근 급격하게 진행 중인 소자구조의 나노화 및 고 단차화에 따라 기존의 증착 기술은 낮은 단차 피복성으로 인하여 한계에 부딪힐 것으로 예상되고 있다. ALD(atomic layer deposition)는 뛰어난 단차 피복성을 가지고 원자단위 두께조절이 용이하여 나노 영역에서의 증착 방법으로 지대한 관심을 받고 있다. 앞선 연구에서 본 연구진은 CoCp2 전구체과 $NH_3$ plasma를 사용하여 Plasma enhanced ALD (PE-ALD)를 이용한 고 순도 저 저항 Co 박막 증착 공정을 개발 하고 이를 SALICIDE 공정에 적용하여 $CoSi_2$ 형성 연구를 보고한 바 있다. 하지만 이 연구에서 PE-ALD Co 박막은 플라즈마 고유의 성질로 인하여 단차 피복성의 한계를 보였다. 이번 연구에서 본 연구진은 Co(AMD)2 전구체와 $NH_3$, $H_2$, $NH_3$ plasma를 반응 기체로 사용하여 Thermal ALD(Th-ALD) Co 및 PE-ALD Co 박막을 증착 하였다. 고 단차 Co 박막의 증착을 위하여 Th-ALD 공정에 초점을 맞추어 Co 박막의 특성을 분석하였으며, Th-ALD 및 PE-ALD 공정으로 증착된 Co 박막의 단차를 비교하였다. 연구 결과 Th-ALD Co 박막은 95% 이상의 높은 단차 피복성을 가져 PE-ALD Co 박막의 단차 피복성에 비해 크게 향상되었음을 확인하였다. 추가적으로, Th-ALD Co 박막에 고 단차 박막의 증착이 가능한 Th-ALD Ru을 capping layer로 이용하여 CoSi2 형성을 확인하였고, 기존의 PVD Ti capping layer와 비교하였다. 이번 연구에서 Co 박막 및 $CoSi_2$ 의 특성 분석을 위하여 X선 반사율 분석법 (XRR), X선 광전자 분광법 (XPS), X선 회절 분석법 (XRD), 주사 전자 현미경 (SEM), 주사 투과 전자 현미경 (STEM) 등을 사용하였다.