• 통합자연과학논문집
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• 제14권1호
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• pp.1-5
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• 2021

라디오 진동수 스퍼터를 이용하여 실리콘(110) 기판위에 증착시간을 60분, 120분 그리고 180을 변화시켜서 산화아연 박막을 만들었다. ZnO₂ 박막의 입자 성장면을 X선 회절 장치를 써서 분석한 결과 박막의 주 성장면(002)면과 (103)면의 방향이 증착 시간의 영향을 많이 받았다. 전자 주사 현미경을 통하여 ZnO₂박막의 입자 성장을 관찰 한 결과 ZnO₂박막이 증착 초기에는 성장이 정체되는 인큐베이션 시간이 필요하다가 일정 시간이 지나면 다시 입자 성장이 일어나는 현상이 관찰 되었다. ZnO₂박막의 화학 분석을 한 결과는 증착 시간의 증가가 ZnO₂박막내의 산소의 양과는 변화가 없었지만 Zn의 성분에 변화가 관찰 되어서 박막의 증착 시간이 박막내의 Zn성분에는 영향을 미침을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제22권5호
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• pp.467-475
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• 2001

A triblock copolymer based on $poly(\varepsilon-caprolactone)$ (PCL) as the hydrophobic part and poly(ethylene glycol) (PEG) as the hydrophilic portion was synthesized by a ring-opening mechanism of ${\varepsilon}-caprolactone$ with PEG containing a hydroxyl group at bot h ends as an initiator. The synthesized block copolymers of PCL/PEG/PCL (CEC) were confirmed and characterized using various analysis equipment such as 1H NMR, DSC, FT-IR, and WAXD. Core-shell type nanoparticles of CEC triblock copolymers were prepared using a dialysis technique to estimate their potential as a colloidal drug carrier using a hydrophobic drug. From the results of particle size analysis and transmission electron microscopy, the particle size of CEC core-shell type nanoparticles was determined to be about 20-60 nm with a spherical shape. Since CEC block copolymer nanoparticles have a core-shell type micellar structure and small particle size similar to polymeric micelles, CEC block copolymer can self-associate at certain concentrations and the critical association concentration (CAC) was able to be determined by fluorescence probe techniques. The CAC values of the CEC block copolymers were dependent on the PCL block length. In addition, drug loading contents were dependent on the PCL block length: the larger the PCL block length, the higher the drug loading content. Drug release from CEC core-shell type nanoparticles showed an initial burst release for the first 12 hrs followed by pseudo-zero order release kinetics for 2 or 3 days. CEC-2 block copolymer core-shell type nanoparticles were degraded very slowly, suggesting that the drug release kinetics were governed by a diffusion mechanism rather than a degradation mechanism irrelevant to the CEC block copolymer composition.

• 한국표면공학회지
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• 제54권6호
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• pp.365-370
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• 2021

In this research, we proceeded with research on plasma resistance of the cleaning process of APS(Atmospheric Plasma Spray)-Y₂O₃ coated parts used for semiconductor and display plasma process equipment. CF₄, O₂, and Ar mixed gas were used for the plasma environment, and respective alconox, surfactant, and piranha solution was used for the cleaning process. After APS-Y₂O₃ was exposed to CF₄ plasma, the surface changed from Y₂O₃ to YF₃ and a large amount of carbon was deposited. For this reason, the plasma corrosion resistance was lowered and contamination particles were generated. We performed a cleaning process to remove the defect-inducing surface YF₃ layer and carbon layer. Among three cleaning solutions, the piranha cleaning process had the highest detergency and the alconox cleaning process had the lowest detergency. Such results could be confirmed through the etching amount, morphology, composition, and accumulated contamination particle analysis results. Piranha cleaning process showed the highest detergency, but due to the very large thickness reduction, the base metal was exposed and a large number of contaminated particles were generated. In contrast, the surfactant cleaning process exhibit excellent properties in terms of surface detergency, etching amount, and accumulated contamination particle analysis.

• Journal of Ecology and Environment
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• 제39권1호
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• pp.17-29
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• 2016

We conducted the study on the relationship between the distribution of coastal sand dune plants and edaphic factors from the shoreline to inland in sand dune ecosystem. The application of TWINSPAN classification based on 10 species, led to the recognition of three vegetative groups (A-C), which associated with their habitats (foredune, hummuck in semistable zone and stable zone). The associations were separated along soil gradient far from the seashore. The relationships between species composition and environmental gradients were explained by canonical correspondence analysis (CCA). Distance from the shoreline was an important indicator to determine soil properties (pH, total ion contents, sand particle sizes, organic matters and nitrogen contents) from the seaward area to inland area and distribution pattern of coastal sand dune plants. Group A is foredune zone, characterized by Calystegia soldanella; group included typical foredune species such as Elymus mollis, Carex kobomugi, Ixeris repens, C. soldanella and Glehnia littoralis. Group B on semi-stabilized zone was characterized by Vitex rotundifolia, a perennial woody shrub. This group was associated the proportion of fine sand size (100 to 250 μm). The results on the proportion of soil particle size showed a transition in sand composition, particularly with respect to the proportion of fine sand size that occurred from the foredune ridge at 32.5 m to the Vitex rotundifolia community at 57.5 m from the shoreline. Group C on stabilized zone was characterized by Zoysia macrostachya, Lathyrus japonicus and Cynodon dactylon and were associated soil organic matter and nitrogen contents. The spatial distribution of plants in the Goraebul coastal sand dune system may result from the interactions between the plant species and environmental heterogeneity.

• 천문학회보
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• 제38권2호
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• pp.95.2-95.2
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• 2013

The Van Allen Probes were designed to study the Earth's radiation belts on various scales of space and time. The identical two spacecrafts going nearly eccentric orbits lap each other several times over the course of the mission and each probe carries five instrument suites to address the science objectives on the radiation belt. Since Van Allen Probes launched on August 30, 2012, the probes detecte several storm events up to now. To understand the particle acceleration and loss mechanism in the radiation belt, we first focus on the energetic electrons' dynamics detected by ECT (Energetic Particle, Composition, and Thermal Plasma Suite). ECT measures near-Earth space's radiation particles covering the full electron and ion spectra from ~ eV to 10's of MeV with sufficient energy resolution. In this paper, we present the preliminary results of the recent several storm events using electron data from ECT(MagEIS and REPT).

• 한국대기환경학회지
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• 제10권1호
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• pp.32-40
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• 1994

Continuous measurements of the extinction coefficient( $b_{ext}$ ) and scattering coefficient due to Particle( $b_{sp}$ ) were made during the fall 1993 in Seoul along with the measurements of the size distribution, ionic composition of particles. On the average, $b_{sp}$ values are 55% and 79% of $b_{ext}$ values during the clear and smoggy Periods respectively. Also the average values of $b_{ext}$ and $b_{sp}$ were 0.791$\times$10$^{-3}$ $m^{-1}$ (visual range 4.9km) and 0.628$\times$10$^{-3}$ $m^{-1}$ (visual range 6.2km) during the smoggy Period, and 0.297$\times$10$^{-3}$ $m^{-1}$ (visual range 13.1km) and 0.164$\times$10$^{-3}$ $m^{-1}$ (visual range 23.8km) during the clear period, respectively. The Peak at about 1${\mu}{\textrm}{m}$ of the Particle size distribution during the smoggy period is about four times higher than that during the clear period while the peaks at about 5${\mu}{\textrm}{m}$ during both periods are similar. Also, the concentrations of sulfate and nitrate at about 1${\mu}{\textrm}{m}$ during the smoggy Period are much higher than these during the clear Period.eriod.

• Current Photovoltaic Research
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• 제3권2호
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• pp.65-70
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• 2015

We applied KF on CIGS film to modify CIGS surface with a wider-bandgap surface layer. With the KF deposition the surface of CIGS film had fine particle on the CIGS surface at 350 and $300^{\circ}C$. No fine particle was detected at 500 and $250^{\circ}C$. With the KF treatment, the Ga and O content increased at the surface, while the In and Cu content decreased. The valence band maximum was lowered with KF treatment. The composition profile and band structure were positive side of applying KF on the CIGS surface. However, the efficiency decreased with the KF treatment due to high series resistance, probably due to too thick surface layer. A smaller amount of KF should be supplied and more systematic analysis is necessary to obtain a reproducible higher efficiency CIGS solar cells.

• Composites Research
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• 제12권6호
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• pp.83-89
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• 1999

고무/폴리머 복합재료의 충격강도와 파괴 기구를 기지재의 체인 유연성을 나타내는 특성비 $C_{\infty}$와 강화고무의 입자 크기의 두 가지 관점에서 연구하였다. 본 연구에서 특성비는 PPO와 PS폴리머의 조성비에 의하여 조절하였다. 아이조드 충격 시험과 주사전자현미경에 의한 파단면 관찰을 수행하였다. 전단항복과 크래이징으로 대별되는 소성 변형 기구의 이해를 넓히기 위해 유한요소해석을 수행하였다. 전단항복은 폴리머의 유연성이 상대적으로 낮거나 고무의 입자 크기가 작은 경우에 잘 나타났다.

• 공업화학
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• 제8권2호
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• pp.230-236
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• 1997

Isophorone diisocyante(IPDI), 각각 에스터와 에테르 타입의 폴리올인 poly[butyl/ethylene adipate] glycol(PBEAG), poly[oxytetramethylene] glycol(PTMG)과 잠재적 음이온기인 dimethylol propionic acid(DMPA)로부터 음이온성 폴리우레탄 분산체(PUD)를 제조하였다. 폴리올의 종류 및 조성이 PUD의 유화 입경과 건조 필름의 기계적, 열적 성질에 미치는 영향 등을 검토하였다. 혼합된 폴리올의 조성 변화 시, PTMG 함량이 증가할수록 PUD의 유화 입경은 점근적으로 증가하는 경향을 보였고, 인장 강도는 완만한 감소를 나타내다가 증가하였다. 이는 두 폴리올간의 상용성이 적기 때문에 나타나는 결과로 해석되며, 이러한 비상용성은 DSC분석을 통하여 유리전이온도(Tg) 측정으로부터 확인할 수 있었다.

• 한국세라믹학회지
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• 제35권6호
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• pp.559-568
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• 1998

Studies of preparation condition and characteristics of AUC(ammonium uranyl carbonate) were carried out to optimize AUC process with different reactor sizes and precipitation methos. As results four types of precipitates with different chemical compositions and morphologies were obtained from the reaction of {{{{ {(NH }_{4 }) { }_{2 } {CO }_{3 } }} with {{{{ {UO }_{2 }( {NO }_{3 }) { }_{2 } }} solution. A phase diagram has been made and crystal structure and chemical composition of each phase have been characterized by using SEM X-ray IR and thermal analysis. It was found that ammonium uranyl carbonate {{{{ {(NH }_{4 }) { }_{4 } {UO }_{2 } {(CO }_{3 }) { }_{3 } }} with monoclinic crystal morphology could be syn-thesized when the mole ratio of in {{{{ {(NH }_{4 }) { }_{2 } {CO }_{3 }/ {UO }_{2 } {(NO }_{3 }) { }_{2 } }} in the solution was higher than 5 Also a mechanism and a precipitating condition on rounding of the AUC particle were examined in the course of the AUC pre-cipitation. The rounding of the AUC particle was possible only by external circulation using pump not by internal circulation using agitator.