• 한국세라믹학회지
• /
• 제24권2호
• /
• pp.101-110
• /
• 1987

The relative electrical conductivity of vacuum deposited Al films on a soda-lime(2947) and an alumino boro silicate(7809) glass was investigated with the variation of the relative humidity,temperature and film thickness. The structure and microstructure of Al films before and after exposure to the humidity wereexamined by the X-ray Diffractormenter(XRD) and Scanning Electron Microscope(SEM). As the relative humidity increased, the electrical conductivity of Al films on both glasses was decreased. However, the Al films on 7809 glass showed higher conductivity than that of 2947 glass under the same testing conditions. The decreasing of electrical conductivity was caused by the formation of Aluminum hydroxide which was made by the reaction between the aluminum films and water vapor.

• 한국자원리싸이클링학회:학술대회논문집
• /
• 한국자원리싸이클링학회 2003년도 추계정기총회 및 국제심포지엄
• /
• pp.252-257
• /
• 2003

본 연구에서는 국내 재생 알루미늄업체에서 발생된 알루미늄 폐드로스를 수산화나트륨 용액으로 침출하여 폐드로스 중의 잔류 알루미늄을 용액 상으로 침출, 분리시킨 다음, 침출용액 중에서 알루미늄 성분을 수산화알루미늄으로 제조하는 연구를 수행하였다. 또한, 연구결과의 상용화를 위하여 시범생산라인을 건설하고, 수처리 응집제용으로 사용하기 위한 시제품을 시험 생산하였다.

• 한국세라믹학회지
• /
• 제25권6호
• /
• pp.655-664
• /
• 1988

As a part of study to establish the industrial process for manufacturing high purity alumina powder which is largely used as fine ceramics, an adsorption method using a silica-containing material which can absorb to eliminate a major impurity, Na in aluminum hydroxide as a raw material has been studied. It is confirmed that the primary property of powder such as the particle size of raw material and that of silica-containing material plays a great important role in the purification process.

• Journal of the Korean Wood Science and Technology
• /
• 제49권1호
• /
• pp.44-56
• /
• 2021

소방청의 방염성능기준에 제시된 45°멕켈 버어너법을 이용하여 물유리 농도와 첨가제 종류에 따른 합판의 탄화길이 및 면적 등의 방염성능을 측정하였다. 합판에 농도 20-50%의 물유리를 처리한 결과, 방염성능은 물유리의 농도와 비례하는 경향을 나타냈다. 그러나 30%를 넘는 고농도의 물유리로 처리된 합판의 표면에서 백화현상과 끈적임이 발생하여 농도 30%를 최적 조건으로 결정하였다. 농도 30%의 물유리에 서로 다른 비율의 첨가제를 추가하여 실험을 수행한 결과, 수산화칼륨 15% 조건과 수산화알루미늄 1-10%의 조건에서 방염성능 기준을 만족하였다. 반면에 황산마그네슘은 방염성능에 크게 영향을 미치지 않았다. 물유리와 첨가제에 따른 방염성능의 결과는 방염제를 활용한 불연재에 대한 기초자료로 활용될 것으로 기대된다.

• Restorative Dentistry and Endodontics
• /
• 제20권2호
• /
• pp.399-422
• /
• 1995

The purpose of this study was to investigate a fragment of possibility of pulpotomy with the Nd-YAG laser by the observation of pulpal healing process and the fine structural changes of the fibroblasts of the remaining pulpal tissues. Class V cavities on !55 teeth from 4 adult dogs were prepared and the pulp chambers were opened with a sterilized round bur. In the control group(19 teeth), the exposed coronal pulps were excised by a sharp excarvator. After bleeding was controlled with the sterilized cotton pellets, calcium hydroxide powder was applied on the remaining pulpal tissues and the cavities were sealed with Z.O.E. In the experimental group 1 : the pulpotomy with laser-calcium hydroxide powder application group(l9 teeth), the exposed coronal pulps were excised by Nd-YAG laser(10 watts power, 2 psi water, 20 psi air) for 2 or 3 seconds and calcium hydroxide powder was applied on the remaining pulpal tissues and the cavities were sealed with Z.O.E. In the experimental group 2 : the pulpotomy with laser-no calcium hydroxide powder application group(17 teeth), after amputating the coronal pulps with Nd-YAG laser as the experimental group 1, the remaining pulpal tissues were covered with stenilized aluminum foil and the cavities were filled with Z.O.E. The animals were sacrificed at the intervals of 1, 2, 3 and 4 weeks. All the teeth were rouutinely processed and the remaining pulpal tissues were observed by the light microscope and electron microscope. The results were as follows : 1. In light microscopic findings, there was no significant difference of the inflammatory response in the remaining pulpal tissues between the control group and the experimental groups. In both of the experimental group 1 : pulpotomy with laser-calcium hydroxide powder application group and the control group, the dentin bridges were observed after 2 weeks and the structure of the dentin bridge was almost same. In the experimental group 2 : pulpotomy with laser-no calcium hydroxide powder application group, the fibrous layers instead of dentin bridge were observed on the superficial portion of the remaining pulpal tissues after 2 weeks and they were consisted with densely crowded active fibroblasts. 2. In the electronmicroscopic findings, the active fibroblasts in the experimental groups were more frequently observed than in the control group at 1 week. But active fibroblasts were found with same frequency after 2 weeks in all of the control group and the experimental groups. 3. General distortions of the cell such as loss of the cell membrane, vaculoization of the cell etc. were observed at the suberficial layer of the remaining pulpal tissues and the carbonization was found in the dentinal wall in 1 week of the experimental groups. 4. In the experimental group 2 : pulpotomy with laser-no calcium hydroxide powder application group, the activity and the density of the fibroblasts in the fibrous layer were more than those in the deep portion of the remaining pulpal tissues after 2 weeks. 5. In the control group, bacteria such as cocci and bacilli were observed frequently, but in the experimntal groups, they could not be observed.

• 한국수소및신에너지학회논문집
• /
• 제20권1호
• /
• pp.1-8
• /
• 2009

Hydrogen production by the reaction of aluminum alloys and NaOH solution was studied for an automotive proton exchange membrane fuel cell(PEMFC) application. In our experiment conditions($30{\sim}75^{\circ}C$, NaOH $0.5{\sim}5M$), passivation of aluminum was not occurred. Higher rate of hydrogen production was observed at the reaction with Al alloys that contain impurities. With an increase in reaction temperature, hydrogen production rate by an increase in NaOH concentration increased much. When hydrogen was fed into the anode without filtering, PEMFC cell performance decreased 35% by ionic contamination such as $Na^+$ on the membrane and electrode. Thus, filtering of produced hydrogen is necessary for PEMFC operation.

• Composites Research
• /
• 제32권6호
• /
• pp.368-374
• /
• 2019

무기필러가 첨가된 현무암섬유 강화 에폭시 복합재료를 제조하여 그 특성을 평가하였다. 첨가된 무기필러는 각각 수산화마그네슘, 수산화알루미늄, 알루미나, 베마이트이며 이를 첨가제로한 에폭시 수지를 현무암섬유에 핸드레이업으로 함침시킨 후 hot pressing하여 수지 함침량이 30 wt%인 섬유복합재료를 제조하였다. LOI 평가 결과 BFRP의 LOI (28.9)는 에폭시 수지 (21.4)에 비해 향상된 것을 확인하였으며 무기필러가 첨가될 경우 그보다 더욱 향상되는 것을 확인하였다. 또한 무기필러가 첨가된 복합재료는 무기필러가 첨가되지 않은 복합재료에 비해 콘칼로리미터 시험에서 PHRR, THR, TSR 등이 감소하여 무기필러 첨가에 따른 난연 특성 향상을 확인하였다.

• 대한예방한의학회지
• /
• 제15권3호
• /
• pp.163-178
• /
• 2011

Objective : This study is conducted to evaluate the efficiency of ethanol extracts of 4 mixed herbs(CP001 or CP002) on mouse model of atopic dermatitis induced by ovalbumin. Methods : Female BALB/c mice were internally sensitized with ovalbumin($20{\mu}g$) plus aluminum hydroxide hydrate(4mg) once per week. After 3 weeks, they were dermally challenged with patches containing ovalbumin ($100{\mu}g$) plus aluminum hydroxide hydrate(20mg) every other day for 3 weeks. After induction of atopic dermatitis, mice back skin were gently rubbed with CP001 or CP002(200mg/$m{\ell}$, $100{\mu}{\ell}$) for two weeks(every 2 days). Results : In CP001 or CP002 treated group, there was a remarkable reduction in infiltration of eosinophils on the skin areas and diminution of mast cells and total T cells in blood samples as compared with control group. Cutaneous expressions of interleukin-13, 17 were also decreased by CP001 or CP002. Moreover, blood immunoglobulin E level was decreased by drug administration while there was no decrease in OVA sensitization group. Conclusion : In summary, our result shows that herbal extracts(CP001 and CP002) could be potential candidates for the treatment of chronic atopic dermatitis.

• 한국전기전자재료학회논문지
• /
• 제28권1호
• /
• pp.51-56
• /
• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.

• 한국재료학회지
• /
• 제20권2호
• /
• pp.97-103
• /
• 2010

In this study, a new, relatively simple fabrication method for forming a mesoporous $Al(OH)_3$ film on Al substrates was demonstrated. This method, i.e., alkali surface modification, was simply comprised of dipping the substrate in a $5\times10^{-3}$ M NaOH solution at $80^{\circ}C$ for one minute and then immersing it in boiling water for 30 minutes. After alkali surface modification, a mesoporous $Al(OH)_3$ film was formed on the Al substrate, and its chemical state and crystal structure were confirmed by XPS and TEM. According to the results of the XPS analysis, the flake-like morphology after the alkali surface modification was mainly composed of $Al(OH)_3$, with a small amount of $Al_2O_3$. The mesoporous $Al(OH)_3$ layer was composed of three regions: an amorphousrich region, a region of mixed amorphous and crystal domains, and a crystalline-rich region near the $Al(OH)_3$ layer surface. It was confirmed that the stabilization process in the alkali surface modification strongly influenced the crystallization of the mesoporous $Al(OH)_3$ layer.