• Journal of Radiation Protection and Research
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• 제15권2호
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• pp.51-56
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• 1990

대기로 방출된 방사성 물질의 대기 확산 형태를 파스킬의 대기안정도에 따른 모델인 타원형 근사화 모델로 가정하고 인체가 받을 수 있는 감마선에 의한 피폭선량률을 계산하였다. 이 결과를 대기 확산 기본 모델인 가우스플룸 모델을 적용하여 계산한 결과 및 이미 발표된 원형 근사화 모델에 의한 결과와 비교하여 보았다. 제시한 타원형 근사화 모델을 이용하여 피폭선량을 계산한 결과는 가우스플룸 모델의 결과와 비슷하고, 원형 근사화 모델의 경우보다 오차가 적었으며, 동시에 기본 모델인 가우스 플룸 모델과 비교할 때 1/40 정도의 계산 시간이 걸렸다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.153-153
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• 2008

Practical application of single-walled carbon nanotubes (SWCNTs) qualified as a promising material has been limited by either poor dispersion or their insolubility in aqueous or organic media due to formation of bundling by relatively high surface energy. Thus, major attention to overcome this issue has been paid at surface modification of CNTs by functionalization, but this introduces defects to the sidewall of CNTs, consequently perturbing the inherent electronic and optical properties. Therefore, using surfactants is a general approach to disperse SWCNTs with lower damages by which bundled nanotubes could be dispersed up to the level of individuals or small bundles. Here, we have investigated various surfactants for their efficiency in dissolving purified SWCNTs produced by arc discharge in deionized water. To compare the surfactants respectively, we have determined the least amount of each surfactant to suspend the nanotubes under optimized experimental conditions(CNT amount, sonication power, and centrifugation speed, etc.) set on the basis of the most common surfactant (sodium dodecyl sulfate, SDS) and discussed the qualitative and quantitative characterization of SWCNT dispersions by UV-Vis absorption spectroscopy. Quantitative aspect about nanotube dispersion was that in particular N-methyl-2-pyrrolidone (NMP) and sodium dodecylbenzene sulfonate (NaDDBS) were found to be effective in dispersing individual tubes.

• 대한화장품학회지
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• 제29권1호
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• pp.135-150
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• 2003

This study is described the stabilizing technology of water-in-oil (w/o) emulsion and the mechanism of emulsification with quaternium-18 hectorite (Q-18 HTRT) by swelling action. When Q-18 HTRT is dispersed in oil, it swells and constructs card-house structure adding ethanol, and formation of water phase is caused by hydrogen bonding. The gelling activities of Q-18 HTRT were excellent such as mineral oil, squalane, cetostearyl isononanoate, isostearic acid, cetyl octanoate, octyl dodecanol and so on. Especially, when oil gel containing Q-18 HTRT passed one to three times by Roll mill. It made the W/O emulsion cream (W/O-ECRM) having 2.0 w/w% of Q-18 HTRT and also produced the control sample (control) including 3.0 w/w% of cetyl PEG/PPG- l0/l dimethicone. The stability of after 24 weeks, Hardness of W/O-ECRM dropped 7.48%, whereas hardness of control went down 57 71%. As a result of these test emulsification of W/O-ECRM is superior compared with control. In cosmetic, 0-18 HTRT can use as suspending agent, oil adsorbent, emulsifying agent, dispersing agent, viscosifier and pigment.

• 한국세라믹학회지
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• 제37권7호
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• pp.693-699
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• 2000

Casting behavior of Zr(Y,Ce)O2 TZP/Mullite suspension during pressure filtration was investigated to prepare multi-layered Functionally Gradient Materials(FGM). The dispersion stabilities of each layer suspension were investigated by examination of zeta potential and viscosity. The each suspensions with 20 vol.% solid loading and 100 첸 of viscosity was prepared after fix of the dispersing agent (Sodium hexa-meta phosphate) and the binder (Hydroxyethyl cellulose), and then the cakes were formed at the 2.5 MPa~10.0MPa pressure range. The cake thickness of all suspensions was increased with the square root of time at the constant pressure, and the relations between filtration pressure(P)a nd dehydration rate (Q=dh/dt) showed that the flows of filtrates in the consolidated layers were laminar. The permeabilities were nearly constant during filtration, and kozeny constants(Kc) of the suspensions were 4.8~6.7. These valumes were seen as close to 5, which might be homogeneous particle packing during filtration. On the basis of those data, the multi layered compaction with 9 mm thickness and 52.5% green density was prepared by continuous pressure filtration.

• 한국대기환경학회지
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• 제24권1호
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• pp.55-62
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• 2008

This study is aimed at substantially reducing the particulate matter (dust) emission during the combustion of heavy fuel in boilers by addition of combustion improver. The combustion improver used were the oil-soluble organometallic compounds that were found to be more effective than the dispersing agents that are generally used for reducing the particulate emission. The dust reduction effect was found to depend on the active materials (metals) as well as on the organic ligand part of organometallic compounds. Acetylacetonoate and naphthenate of Fe and Ca were found to be most effective for dust reduction. Addition of Fe and Ca organometallic compounds as combustion improver in concentration of 30 ppm (metal basis) to heavy fuel oil, caused dust reduction by 50 wt% to 80 wt%.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2107-2115
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• 2018

Over recent years, high-concentration of particulate matters (e.g., a.k.a. fine dust) in South Korea has increasingly evoked considerable concerns about public health. It is intractable to track and report $PM_{10}$ measurements to the public on a real-time basis. Even worse, such records merely amount to averaged particulate concentration at particular regions. Under this circumstance, people are prone to being at risk at rapidly dispersing air pollution. To address this challenge, we attempt to build a predictive model via deep learning to the concentration of particulates ($PM_{10}$). The proposed method learns a binary decision rule on the basis of video sequences to predict whether the level of particulates ($PM_{10}$) in real time is harmful (>$80{\mu}g/m^3$) or not. To our best knowledge, no vision-based $PM_{10}$ measurement method has been proposed in atmosphere research. In experimental studies, the proposed model is found to outperform other existing algorithms in virtue of convolutional deep learning networks. In this regard, we suppose this vision based-predictive model has lucrative potentials to handle with upcoming challenges related to particulate measurement.

• 한국표면공학회지
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• 제53권1호
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• pp.22-28
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• 2020

In this study, manganese dioxide (MnO₂) nanoparticles were synthesized from KMnO₄ and MnCl₂·4H₂O without any dispersing agents and oxidant via ultra-high pressure homogenization process. We investigated various physicochemical properties and CO oxidation reactions of the MnO₂ nanoparticles as a function of the number of passes at 1,500 bar in a high pressure homogenizer nozzle. The observed X-ray diffraction patterns and scanning electron microscopy images revealed that the synthesized MnO₂ nanoparticles had a hexagonal structure and a uniform spherical shape. It was found from the Brunauer-Emmett-Teller measurements that the pore size of the MnO₂ nanoparticles ranged from 23.6 to 7.2 nm and their specific surface area ranged from 24 to 208 m²g^-1. In particular, it was confirmed from the measurements of CO conversion into CO₂ that CO oxidation reaction over the MnO₂ nanoparticles exhibited excellent catalytic activity at low temperatures below 100℃.

• The Korean Journal of Physiology
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• 제7권2호
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• pp.59-66
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• 1973

It has been reported that vasopressin disperse the melanophore granule of frog skin. The author used hypophysectomized and adrenergic receptor blockaded animals in order to define the mechanism of vasopressin on the melanopore pigment of frog skin. The Rana niglomaculata which could be found in the Seoul area were used on this experiment. The amount of the following drugs were injected into the lymphatic sac of the frog; vaospressin $(0.05\;{\mu}g/g\;B.W.)$, dibenzylin $(0.05\;{\mu}g/g\;B.W.)$, and propranolol $(0.01\;{\mu}g/g\;B.W.)$. The following results were observed; 1. Vasopressin dispersed the melanin granules of melanocyte of frog skin. 2. The melanin granule dispersion activity of vasopressin was observed on the hypophysectomized frog. 3. The melanin granule dispersion was observed on the adrenergic receptor blockaded frog with dibenzylin or propranolol respectively, especially the later one was found to be more obvious. 4. The melanin granule dispersion was observed on the frog which was injected with vasopressin after alpha-receptor or beta-receptor blockade and the later one was found to be more obvious. 5. The melanin granule dispersion was more effective with the blockade of beta-receptor after the treatment with vasopressin on hypophysectomized frog.

• Journal of Pharmaceutical Investigation
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• 제30권4호
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• pp.273-278
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• 2000

Several topical preparations containing lidocaine, a widely used local anesthetic agent, have been developed and marketed recently for the treatment of premature ejaculation. In this study, microemulsion(ME)-based hydrogels containing lidocaine were prepared by dispersing ME to hydrogel bases such as Carbopol, sod. alginate, and sod. carboxymethylcellulose. Lidocaine-containing ME was thermodynamically stable over 6 months and had a diameter ranging from 10 to 100 nm. In vitro skin penetration of lidocaine from ME-based hydrogels followed apparent zero-order kinetics. ME-based hydrogel showed higher drug penetration during fifteen minutes after application than alcoholic hydrogel, reference preparation. Tail flick test in rat was introduced to compare in vivo local anesthetic effects of different hydrogels, and the results showed that ME-based hydrogels are superior to other hydrogels. In optical microscopy, recrystallization of lidocaine was observed within 5 min after application of reference hydrogel, but there was no change in ME-based hydrogels even after 30 minnute. These results indicated that ME-based hydrogels had some advantages in skin penetration, anesthetic effect and physical stability compared with alcoholic hydrogels. Finally it is possible to conclude that ME-based hydrogels containing lidocaine is a good topical drug delivery system for the treatment of premature ejaculation.

• 전력전자학회논문지
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• 제11권6호
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• pp.508-519
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• 2006

본 논문에서는 태양광 발전 시스템 중 태양전지의 효과적인 사용을 위해 태양이 항상 법선을 이루면서 태양전지 모듈에 입사되게 하는 위치추적 시스템에 대한 새로운 방법을 제시하였다. 점 하중 방식인 해바라기 타입의 태양광 추적 장치의 단점을 극복하기 위해 선 하중 방식 태양광 발전 시스템으로 경제적인 태양광 추적 장치를 제안하였다. 제안된 방식에 대하여 여러 가지 검증된 태양 기하학 이론을 바탕으로 현재 사용 중인 프로그램 방식의 위치추적 시스템을 개선할 수 있는 제어방법 및 구조를 도출하고자 한다.