• 센서학회지
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• 제25권4호
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• pp.275-279
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• 2016

Chemical vapor deposited (CVD) polycrystalline graphene is widely used for various sensor application because of its extremely large surface-to-volume ratio. The electrical properties of CVD-graphene is significantly affected by the grain size and boundaries (GGBs), but evaluation of GGB of continuous monolayer graphene is difficult. Although several evaluation methods such as tunneling electron microscopy, confocal Raman, UV/ozone-oxidation are typically used, they still have issues in evaluation efficiency and accuracy. In this paper, we suggest an improved evaluation method for precise and simple GGB evaluation which is based on UV/ozone-oxidation and chemical etching process. Using this method, we could observe clear GGBs of CVD-graphene layers grown by different process conditions and statistically evaluate average grain sizes varying from $1.69{\sim}4.43{\mu}m$. This evaluation method can be used for analyzing the correlation between the electrical properties and grain size of CVD-graphene, which is essential for the development of graphene-based sensor devices.

• 한국환경과학회지
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• 제16권4호
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• pp.433-440
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• 2007

The photodegradation and by-products of the gaseous toluene with $TiO_2$ (P25) and short-wavelength UV ($UV_{254+185nm}$) radiation were studied. The toluene was decomposed and mineralized efficiently owed to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the $TiO_2$ surface. The toluene by the $UV_{254+185nm}$ photoirradiated $TiO_2$ were mainly mineralized $CO_2$ and CO, but some water-soluble organic intermediates were also formed under severe reaction conditions. The ozone and secondary organic aerosol were produced as undesirable by-products. It was found that wet scrubber was useful as post-treatment to remove water-soluble organic intermediates. Excess ozone could be easily removed by means of a $MnO_2$ ozone-decomposition catalyst. It was also observed that the $MnO_2$ catalyst could decompose organic compounds by using oxygen reactive species formed in process of ozone decomposition.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Pre-symposium of the 10th ISWPC Recent Advances in Paper Science and Technology
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• pp.375-380
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• 1999

In order to improve the optical properties of high yield pulp, bleached chemi-thermo-mechanical pulp (BCTMP) was produced from CTMP of Betula maximowicziana Regel by two staged ozone-hydrogen peroxide bleaching. This pulp was used for the evaluation of the improvement of optical properties, chemical characteristics of lignin in fiber, and the relationship between lignin and optical properties in fiber cell wall. By hydrogen peroxide treatment, the brightness was improved, but the post color number (PC No.) was not. There was little improvement on optical properties by ozone treatment, but his could be solved by using two staged ozone-hydrogen peroxide bleaching. The hydrogen peroxide treatment did not make nay change on chemical characteristics of lignin in cell wall, but by ozone treatment, it was found that the non-aromatic conjugated structure was existed in the surface of cell wall, but this could be removed by hydrogen peroxide treatment in two staged ozone-hydrogen peroxide treatment. Therefore, the optical properties was significantly improved due to the removal of non-aromatic conjugated structure.

• 한국환경과학회지
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• 제18권4호
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• pp.445-450
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• 2009

In this study, the fundamental experiments were performed for catalytic oxidation of NO (50 ppm) on $MnO_2$ in the presence of ozone. The experiments were carried out at various catalytic temperatures ($30-120^{\circ}C$) and ozone concentrations (50-150 ppm) to investigate the behavior of NO oxidation. The honeycomb type $MnO_2$ catalyst was rectangular with a cell density of 300 cells per square inch. Due to $O_3$ injection, NO reacted with $O_3$ to form $NO_2$, which was adsorbed at the $MnO_2$ surface. The excessive ozone was decomposed to $O^*$ onto the $MnO_2$ catalyst bed, and then that $O^*$ was reacted with $NO_2$ to form $NO_3^-$. It was found that the optimal $O_3$/NO ratio for catalytic oxidation of NO on $MnO_2$ was 2.0, and the NO removal efficiency on $MnO_2$ was 83% at $30^{\circ}C$. As a result, NO was converted mainly to $NO_3^-$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1997년도 제13회 학술발표회 논문개요집
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• pp.156-156
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• 1997

• 신재생에너지
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• 제7권1호
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• pp.22-28
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• 2011

The surface solar radiations were calculated and analyzed with spatial resolutions (4 km and 1 km) using by GWNU (Gangneung-Wonju National University) solar radiation model. The GWNU solar radiation model is used various data such as aerosol optical thickness, ozone amount, total precipitable water and cloud factor are retrieved from Moderate Resolution Imaging Spectrometer (MODIS), Ozone Monitoring Instrument (OMI), MTSAT-1R satellite data and output of the Regional Data Assimilation Prediction System(RDAPS) model by Korea Meteorological Administration (KMA), respectively. The differences of spatial resolutions were analyzed with input data (especially, cloud factor from MTSAT-1R satellite). And the Maximum solar radiation by GWNU model were found in Andong, Daegu and Jinju regions and these results were corresponded with the MTSAT-1R cloud factor.

• 한국지반환경공학회 논문집
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• 제23권3호
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• pp.23-29
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• 2022

본 연구에서는 오존의 용해효율 개선과 자가분해 촉진을 위해 나노기포와 초음파 캐비테이션을 동시에 적용한 오존 나노기포 공정을 조사하였다. 공정의 유기물 분해효율을 파악하기 위해 200mm × 200mm × 300mm 규모의 반응기를 제작하여 다양한 조건에서 페놀 분해 실험을 진행하였다. 나노기포의 사용은 60분 반응에서 페놀 분해 효율을 일반적인 폭기 방식에 비해 2.07배 증가시켰으며, 용존 오존의 최대 용해농도를 크게 증가시켜 오존의 용해효율 개선에 효과적이었다. 초음파 조사는 나노기포와 함께 사용될 때 페놀 분해 효율을 36% 증가시켰으며 오존의 자가 분해 촉진으로 용존 오존은 낮게 나타났다. 초음파 출력이 강할수록 페놀 분해 효율도 증가하였으며, 실험에서 사용한 28kHz, 132kHz, 580kHz 중 132kHz의 주파수에서 페놀의 분해 효율이 가장 높게 나타났다. 오존 나노공정은 기존 오존 공정과 같이 높은 pH에서 더 좋은 분해효율을 보였으나 중성에서도 60분 반응 후 페놀 100% 분해를 달성하여 pH에 의한 영향이 적은 것으로 나타났다. 이는 초음파에 의한 오존 자가분해 촉진에 의한 것으로 판단된다. 초음파 조사에 의한 기포 특성 변화를 확인하기 위해 Zetasizer를 이용하여 기포의 크기와 제타 전위 분석을 진행하였으며 초음파 조사가 기포의 평균 크기를 11% 감소시키고 기포 표면의 음전하를 강화하여 오존 나노기포의 물질전달과 수산화 라디칼 생성 효율에 긍정적인 효과를 끼치는 것을 확인하였다.

• 한국대기환경학회지
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• 제27권1호
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• pp.30-40
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• 2011

Numerical simulations were carried out to investigate the impact of SST spatial distribution on the result of air quality modeling. Eulerian photochemical dispersion model CAMx (Comprehensive Air quality Model with eXtensions, version 4.50) was applied in this study and meteorological fields were prepared by RAMS (Regional Atmospheric Modeling System). Three different meteorological fields, due to different SST spatial distributions were used for air quality modeling to assess the sensitivity of CAMx modeling to the different meteorological input data. The horizontal distributions of surface ozone concentrations were analyzed and compared. In each case, the simulated ozone concentrations were different due to the discrepancies of horizontal SST distributions. The discrepancies of land-sea breeze velocity caused the difference of daytime and nighttime ozone concentrations. The result of statistic analysis also showed differences for each case. Case NG, which used meteorological fields with high resolution SST data was most successfully estimated correlation coefficient, root mean squared error and index of agreement value for ground level ozone concentration. The prediction accuracy was also improved clearly for case NG. In conclusion, the results suggest that SST spatial distribution plays an important role in the results of air quality modeling on high ozone episode at coastal region.

• Journal of Astronomy and Space Sciences
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• 제14권2호
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• pp.297-311
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• 1997

산소 기체($O_2$)를 전기 방전에 의해 완전히 오존($O_3$)으로 만든 후 $30~150^{\circ}C$범위의 온도에서 열분해 시켰다. 열분해 결과 얻어진 산소 기체를 동위원소 질량분석기로 분석하여 동위원소 분할효과를 측정하였다. 낮은 온도에서는 생성된 산소 기체가 오존에 의해 더 가벼우면서 질량에 의존하는 일반적인 동위원소 분할효과를 보이다가, $110^{\circ}C$ 이상의 실험에서는 산소 기체가 더 무거워지면서 $^{17}O$와 $^{18}O$가 $^{16}O$에 비해 같은 양 만큼씩 많아지는 질량과 무관한 분할효과를 나타냈다. 같은 재질(파이렉스)의 반응 관을 이용한 연구들과 그 범위와 경향이 거의 일치하였다. 실험 결과를 이용하여 산소 생성 비율이 일정한 값이 되는 순간의 동위원소 분할 인자들에 대한 값을 최소자승 법을 이용하여 구하였다. 관측된 현상들은 오존의 열분해 메커니즘의 이해와 운석 및 성층권에서의 산소 동위원소의 질량에 무관한 분포에 대한 이해에 중요한 역할을 할 것이다.

• 한국염색가공학회지
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• 제19권3호
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• pp.26-36
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• 2007

This study was carried out to treat the aqueous solutions containing reactive dyes(RB19, RR120 and RY179) by the Ozone demand flask method and adsorption process using activated carbon fiber(ACF) which are one of the main pollutants in dye wastewater. Ozone oxidation of three kinds of the reactive dyes was examined to investigate the reactivity of dyes with ozone, competition reaction and ozone utilization on various conditions for single- and multi-solute dye solution. Concentration of dyes was decreased continuously with increasing ozone dosage in the single-solute dye solutions. Competition quotient values were calculated to investigate the preferential oxidation of individual dyes in multi-solute dye solutions. Competition quotients(CQi) and values of the overall utilization efficiency, ${\eta}O_3$, were increased at 40mg/l of ozone dosage in multi-solute dye solutions. ACF(A-15) has much larger specific surface area$(1,584m^2/g-ACF)$ in comparison with granular activated carbon adsorbent (F400, $1,125m^2/g-GAC$), which is commonly used, and most of pores were found to be micropores with pore radius of 2nm and below. It was found that RB19 was most easily adsorbed among the dyes in this study. In the case of PCP (p-chlorophenol) and sucrose, which are single component adsorbate, adsorption capacities of ACF(A-15) were in good agreement with the batch adsorption measurement, and saturation time predicted of ACF columns for these components was also well agreed with practically measured time. But in the case of reactive dyes, which have relatively high molecular weight and aggregated with multi-components, adsorption capacities or saturation time predicted were not agreed with practically measured values.