• 한국대기환경학회지
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• 제33권2호
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• pp.124-138
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• 2017

Physico-chemical measurement of non-refractory submicron particles($NR-PM_1$) was conducted in Baengnyeong Island, Korea using Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) from 2012 to 2014. Organics and ammoniated sulfate were dominant species in $NR-PM_1$. The organics was found to have similar fractions(approximate 40%) of $NR-PM_1$ during the summer and winter, while the sulfate fractions of $NR-PM_1$ were calculated to be approximately 47% and 31% for the summer and winter, respectively, suggesting the possibility that particles provide non-acidic surfaces for condensation of nitric acid in the winter. The nitrate fractions of approximate 4% and 20% of $NR-PM_1$ were observed in August (summer) and November (winter), respectively, resulting that the relatively low concentration of sulfate in $NR-PM_1$ provided a non-acidic surface for nitric acid condensation and formation of particulate ammoniated nitrate is favored thermodynamically in winter. The new particle formation (NPF) event and particle growth rate were analyzed for each month in 2014 using Scanning Mobility Particle Sizer(SMPS). The Percent of NPF events was the highest in winter, but NPF event was not observed during summer due to relatively high temperature and frequent rainfall. The average particle growth rate was 3.5 nm/h and the highest particle growth rate was 5.5 nm/h in May. We observed the long-range transport of the anthropogenic sulfate from the East Asia during the intensive monitoring period of November between Qingdao and Baengnyeong Island in 2013. The relatively high concentrations of m/z 60 measured in HR-ToF-AMS was observed in May and June at Baengnyeong Island, suggesting the possibility of the influence of biomass burning from the East Asia to the Korean Peninsula.

• 자원환경지질
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• 제32권4호
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• pp.385-398
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• 1999

The Narim gold mine is located approimately 200km southeast of Seoul within the Muju mineralized district of the Sobaegsan gneiss complex, Korea. Environmental geochemistry were undertaken for various kinds of water (surface, ground and mine water) collected of April, September and November in 1998 from the narim mine creek. Hydrogeochemical compositions of water samples are characterized by the relatively significant enrichment of Na+K, alkali ions, $HCO_{3}$, $NO_{3}$, Cl and F in groundwater, wheras the mine and surface waters are relatively enriched in Ca+Mg, hea표 metals and $SO_{4}$. Therefore, the groundwaters belong to the (Na+Ca)-( $HCO_{3}+SO_{4}$) type, respectively. The pH and EC values of the non-mining creek surfers are relatively lower compared with those of the surface water of the mine and ore dump area. The d values ($\delta$D-8$\delta^{18}$O) of all kinds of water from the Narim mine creek are 5.8 to 13.1 The range of $\delta$D and $\delta^{18}$O values (relative to SMOW) are shown in distinct two groups as follows: for the April waters of -64.8 to -67.8$\textperthousand$ and -9.6 to -10.0$\textperthousand$(d value=10.1 to 13.1), and for the November waters of -65.9 to -70.2$\textperthousand$ and -9.3 to -9.6$\textperthousand$ (d value=5.8 to 7.9), respectively. This range variation indicates that two group water were composed of distinct waters with seasonal difference. Geochemical modeling showed that mostly toxic metals (As, Fe, Mn, Ni, Pb, Zn) may exist largery in the from of metal $(M2^+)$ and metal-sulfate $(MSO_4\;^{2-$\mid$),\; and \;SO_4^{2-$\mid$}$ concentration influenced the speciation of heavy metals in the meteoric water. These metals in the groundwater could be formed of $CO_3 \;and \;(OH)_3$ complex ions. Using computer program, saturation index of albite, calcite, dolomite in meteoric water show undersaturated and progreddively evolved toward the saturation state, however, ground and mine water are nearly saturated. The gibbsited water-mineral reaction and stabilities suggest that the weathering of silicate minerals may be stable kaolinite, illite and Nasmectite. The clay minerals will be transformed to more stable kaolinite owing to the contiunous reaction.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.111.2-111.2
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• 2015

Typical electrodes (metal or indium tin oxide (ITO)), which were used in conventional organic light emitting devices (OLEDs) structure, have transparency and conductivity, but, it is not suitable as the electrode of the flexible OLEDs (f-OLEDs) due to its brittle property. Although Graphene is the most well-known alternative material for conventional electrode because of present electrode properties as well as flexibility, its carrier injection barrier is comparatively high to use as electrode. In this work, we performed plasma treatment on the graphene surface and alkali metal doping in the organic materials to study for its possibility as anode and cathode, respectively. By using Ultraviolet Photoemission Spectroscopy (UPS), we investigated the interfaces of modified graphene. The plasma treatment is generated by various gas types such as O2 and Ar, to increase the work function of the graphene film. Also, for co-deposition of organic film to do alkali metal doping, we used three different organic materials which are BMPYPB (1,3-Bis(3,5-di-pyrid-3-yl-phenyl)benzene), TMPYPB (1,3,5-Tri[(3-pyridyl)-phen-3-yl]benzene), and 3TPYMB (Tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane)). They are well known for ETL materials in OLEDs. From these results, we found that graphene work function can be tuned to overcome the weakness of graphene induced carrier injection barrier, when the interface was treated with plasma (alkali metal) through the value of hole (electron) injection barrier is reduced about 1 eV.

• 대한소아치과학회지
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• 제35권2호
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• pp.287-296
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• 2008

본 연구는 항우식 제품인 저농도의 불소 양치액(500 ppm NaF)과 Casein phosphopeptide-amorphous calcium phosphate(CPP-ACP)를 포함하는 치아 연고, 그리고 이 두 제품을 같이 사용했을 경우, 인공 우식 병소의 재광화 효과를 알아보고자 하였다. 제3대구치 협면에 인공우식을 유발하였고, 시편을 16개씩 4군으로 나누어, 28일 동안 매일 2 회 다음과 같은 항우식 제품을 시편에 처리하였고, pH 순환 시스템을 적용하였다. 1군: 대조군(무처치) 2군: Tooth $Mousse^{(R)}$ (GC Co. Japan) 3군: 치카치카$^{(R)}$ (삼일제약. 한국) 4군: 치카치카$^{(R)}$+Tooth Mousse$^{(R)}$ 무기질 소실량(${\Delta}Q$)의 장기적인 변화를 Quantitative light-induced fluorescence(QLF)를 이용하여 관찰하여 다음과 같은 결과를 얻었다. 1. ${\Delta}Q$는 1군에서는 28일동안 유의성 있는 차이를 보이지 않았고, 2군과 3군에서는 처치전에 비해 14일부터 유의성 있는 증가를 보였으며, 4군에서는 7일부터 유의성 있는 증가를 보였다. 2. ${\Delta}Q$는 1군 < 2군, 3군 < 4군 순이었다. 3. ${\Delta}Q$는 1군과 비교시 2군은 7일, 3군과 4군은 3일부터 유의성 있는 증가를 보였고, 2군은 3군과 전 기간 동안 유의차가 없었다. 4군은 2군과 3군에 비해 28일에 유의성 있는 증가를 보였다. 4. 모든 군에서 재광화 속도는 점차 감소하였다.

• 한국환경농학회지
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• 제33권4호
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• pp.245-253
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• 2014

패화석에 의한 카드뮴의 용출특성과 부동화 기작을 구명하기 위해 우리나라의 대표적인 석회비료인 소석회를 비교구로 선정하여 실내에서 비교시험을 실시하였다. 두 칼슘제재의 처리량을 증가시킴에 따라 토양의 pH와 음하전도는 증가하는 결과를 나타내었으나 소석회가 패화석에 비해 토양의 pH와 음하전도를 증대시키는 효과가 더욱 우수하였다. 소석회는 패화석에 비해 1 N $NH_4OAc$ extractable Cd의 함량을 감소시키는 효과가 더욱 우수한 것으로 조사된 반면 패화석은 소석회에 비해 0.1 N HCl extracble Cd의 함량을 감소시키는 효과가 더욱 우수한 것으로 조사되었다. 본 연구에서 소석회에 의한 카드뮴의 부동화기작은 주로 토양의 음하전도의 증대에 기인된 카드뮴의 흡착에 의한 것으로 판단된다. 그러나 패화석에 의한 카드뮴의 부동화기작은 음하전도의 증대에 기인된 카드뮴의 흡착 이외에 부가적으로 다공성의 패화석 내부에 카드뮴이 물리적으로 흡착되어지는 것에 기인되는 것으로 판단된다. 결과적으로 패화석은 토양 내 식물이 이용하기 쉬운 형태의 카드뮴의 함량(F2)을 저감시키고 식물이 거의 이용하기 힘든 형태의 카드뮴의 함량(F5)을 증가시켜 카드뮴으로 오염되어진 농경지에서 식물의 카드뮴 흡수를 저감시키기 위한 토양개량제로써의 활용가능성이 높은 것으로 평가되었다.

• 반도체디스플레이기술학회지
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• 제5권1호
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• pp.39-43
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• 2006

The polyvinyl series organic films as gate insulators of thin film transistor(TFT) have been processed and characterized on the polyether sulphone (PES) substrates . The poly-4-vinyl phenol(PVP) and polyvinyl toluene (PVT) were used as solutes and propylene glycol monomethyl ether acetate(PGMEA) as a solvent in the formation of organic insulators. The cross-linking of organic insulators was also attempted by adding the thermosetting material, poly (melamine-co-formaldehyde) as a hardener in the compound. The electrical characteristics measured in the metal-insulator-metal (MIM) structures showed that insulating properties of PVP layers were generally superior to those of PVT layers. Among the layers of PVP series; copolymer PVP(10 wt%), 5wt% cross-linked PVP(10 wt%), copolymer PVP(20 wt%), 5 wt% cross-linked PVP(20 wt%) and 10 wt% cross-linked PVP(20 wt%), the 10 wt% cross-linked PVP(20 wt%) layer showed the lowest leakage current of 1.2 pA at ${\pm}10V$. The ms value of surface roughness and the capcitance per unit area are 2.41 and $1.76nF/cm^2$ in the case of 10 wt% cross-linked PVP(20 wt%) layer, respectively.

• 대한원격탐사학회지
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• 제39권6_1호
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• pp.1211-1224
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• 2023

구름은 광학위성을 이용한 국토 관측 및 재난 대응, 변화 탐지 등 지표의 현상을 관측하는데 있어 많은 어려운 문제를 야기한다. 구름의 존재는 영상 처리 단계 뿐만 아니라 최종적으로는 데이터의 품질에 영향을 미치므로 이를 반드시 식별하고 제거하는 과정이 필요하다. 따라서 본 연구에서는 위성영상 내 구름의 분광패턴에 가장 근접한 화소를 탐색 및 추출해 최적의 임계값을 선정하고 임계값을 바탕으로 구름 산출물을 제작하는 일련의 과정을 자동으로 수행하는 새로운 구름 탐지 기법을 개발하고자 하였다. 구름 탐지 기법은 크게 세 단계로 구성된다. 첫 번째 단계에서는 Digital Number (DN) 단위 영상을 대기상층 반사율 단위로 변환하는 과정을 수행한다. 두 번째 단계에서는 대기상층 반사율 영상을 이용하여 Hue-Value-Saturation (HSV) 변환 및 삼각형 임계 처리, 최대우도 분류 등의 전처리를 적용하고 각 영상별로 초기 구름 마스크 생성을 위한 임계값을 결정한다. 세번째 후처리 단계에서는 생성된 초기 구름 마스크에 포함된 노이즈를 제거하고 구름 경계 및 내부를 개선한다. 구름 탐지를 위한 실험 자료로 구름의 공간적, 계절적 분포의 다양성을 보여주는 4~11월 시기에 한반도 지역에서 촬영된 국토위성 L2G 영상을 사용하였다. 제안 방법의 성능을 검증하기 위해 단일 임계화 방법으로 생성된 결과를 비교하였다. 실험 결과, 제안 방법은 기존 방법과 비교하여 전처리 과정을 통해 각 영상의 방사학적 특성을 고려할 수 있어 보다 정확하게 구름을 검출할 수 있었다. 또한, 구름 개체를 제외한 나머지 밝은 물체(판넬식 지붕, 콘크리트 도로, 모래 등)의 영향을 최소화하는 결과를 보여주었다. 제안 방법은 기존 방법 대비 F1-score 기준으로 30% 이상의 개선된 결과를 보여주었으나 눈이 포함된 특정 영상에서 한계점이 있었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.119-120
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• 2004

Urban groundwater has a unique hydrologic system because of the complex surface and subsurface infrastructures such as deep foundation of many high buildings, subway systems, and sewers and public water supply systems. It generally has been considered that increased surface impermeability reduces the amount of groundwater recharge. On the other hand, leaks from sewers and public water supply systems may generate the large amounts of recharges. All of these urban facilities also may change the groundwater quality by the recharge of a myriad of contaminants. This study was performed to determine the factors controlling the recharge of deep groundwater in an urban area, based on the hydrogeochemical characteristics. The term ‘contamination’ in this study means any kind of inflow of shallow groundwater regardless of clean or contaminated. For this study, urban groundwater samples were collected from a total of 310 preexisting wells with the depth over 100 m. Random sampling method was used to select the wells for this study. Major cations together with Si, Al, Fe, Pb, Hg and Mn were analyzed by ICP-AES, and Cl, N $O_3$, N $H_4$, F, Br, S $O_4$and P $O_4$ were analyzed by IC. There are two groups of groundwater, based on hydrochemical characteristics. The first group is distributed broadly from Ca-HC $O_3$ type to Ca-C1+N $O_3$ type; the other group is the Na+K-HC $O_3$ type. The latter group is considered to represent the baseline quality of deep groundwater in the study area. Using the major ions data for the Na+K-HC $O_3$ type water, we evaluated the extent of groundwater contamination, assuming that if subtract the baseline composition from acquired data for a specific water, the remaining concentrations may indicate the degree of contamination. The remainder of each solute for each sample was simply averaged. The results showed that both Ca and HC $O_3$ represent the typical solutes which are quite enriched in urban groundwater. In particular, the P$CO_2$ values calculated using PHREEQC (version 2.8) showed a correlation with the concentrations of maior inorganic components (Na, Mg, Ca, N $O_3$, S $O_4$, etc.). The p$CO_2$ values for the first group waters widely ranged between about 10$^{-3.0}$ atm to 10$^{-1.0}$ atm and differed from those of the background water samples belonging to the Na+K-HC $O_3$ type (<10$^{-3.5}$ atm). Considering that the p$CO_2$ of soil water (near 10$^{-1.5}$ atm), this indicates that inflow of shallow water is very significant in deep groundwaters in the study area. Furthermore, the P$CO_2$ values can be used as an effective parameter to estimate the relative recharge of shallow water and thus the contamination susceptibility. The results of our present study suggest that down to considerable depth, urban groundwater in crystalline aquifer may be considerably affected by the recharge of shallow water (and pollutants) from an adjacent area. We also suggest that for such evaluation, careful examination of systematically collected hydrochemical data is requisite as an effective tool, in addition to hydrologic and hydrogeologic interpretation.ion.ion.

• 구강회복응용과학지
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• 제23권3호
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• pp.249-257
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• 2007

State of problem : The use of zirconium oxide all-ceramic material provides several advantages, including a high flexural strength(>1000MPa) and desirable optical properties, such as shading adaptation to the basic shades and a reduction in the layer thickness. Along with the strength of the materials, the cementation technique is also important to the clinical success of a restoration. Nevertheless, little information is available on the effect of different surface treatments on the bonding of zirconium high-crystalline ceramics and resin luting agents. Purpose : The aim of this study was to test the effects of surface treatments of zirconium on shear bond strengths between bovine teeth and a zirconia ceramic and evaluate differences among cements Material and methods : 54 sound bovine teeth extracted within a 1 months, were used. They were frozen in distilled water. These were rinsed by tap water to confirm that no granulation tissues have left. These were kept refrigerated at $4^{\circ}C$ until tested. Each tooth was placed horizontally at a plastic cylinder (diameter 20mm), and embedded in epoxy resin. Teeth were sectioned with diamond burs to expose dentin and grinded with #600 silicon carbide paper. To make sure there was no enamel left, each was observed under an optical microscope. 54 prefabricated zirconium oxide ceramic copings(Lava, 3M ESPE, USA) were assigned into 3 groups ; control, airborne-abraded with $110{\mu}m$ $Al_2O_3$ and scratched with diamond burs at 4 directions. They were cemented with a seating force of 10 ㎏ per tooth, using resin luting cement(Panavia $F^{(R)}$), resin cement(Superbond $C&B^{(R)}$), and resin modified GI cement(Rely X $Luting^{(R)}$). Those were thermocycled at $5^{\circ}C$ and $55^{\circ}C$ for 5000 cycles with a 30 second dwell time, and then shear bond strength was determined in a universal test machine(Model 4200, Instron Co., Canton, USA). The crosshead speed was 1 mm/min. The result was analyzed with one-way analysis of variance(ANOVA) and the Tukey test at a significance level of P<0.05. Results : Superbond $C&B^{(R)}$ at scratching with diamond burs showed the highest shear bond strength than others (p<.05). For Panavia $F^{(R)}$, groups of scratching and sandblasting showed significantly higher shear bond strength than control group(p<.05). For Rely X $Luting^{(R)}$, only between scratching & control group, significantly different shear bond strength was observed(p<.05). Conclusion : Within the limitation of this study, Superbond $C&B^{(R)}$ showed clinically acceptable shear bond between bovine teeth & zirconia ceramics regardless of surface treatments. For the surface treatment, scratching increased shear bond strength. Increase of shear bond strength by sandblasting with $110{\mu}m$ $Al_2O_3$ was not statistically different.

• Ecology and Resilient Infrastructure
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• 제9권4호
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• pp.228-236
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• 2022

하천의 안정성과 이용도를 높이기 위하여 설치하는 하천 호안이 최우선으로 여기는 가치는 홍수에 견딜 수 있는 치수적인 안전성 확보이다. 이러한 구조물은 물의 하천의 안정성을 확보하면서 호안의 세굴을 막기위해 설치된다. 기존에 하천에 설치된 호안 기술은 사석, 돌망태 및 콘크리트 등으로 구성되어 있다. 하지만 사석 및 돌망태 기술은 급격한 홍수로 인해 쉽게 유실 및 파괴되는 단점을 지니고 있으며, 콘크리트 기술은 소재의 안정성은 강하지만, 물속에 오랜 시간동안 존재할 경우 수생태계에 악영향을 미치는 강염기가 약 10년간 용출되고, 콘크리트 표면에 식생이 성장하지 못하기 때문에 환경 및 생태적인 이유로 문제가 되고 있다. 이에 피마자유에서 추출된 바이오폴리머 소재를 활용하여 다층다공성 하천호안보호기술을 개발하였으며, 한국건설기술연구원 안동하천실험센터에서 실규모 하천실험을 통해 수리학적 안정성 검토결과, 유속 8.0 m/s 및 최대 허용 소류력은 67.25 kg_f/m² (659.05 N/m²)에서 수리적인 안정성을 확인하였다.