Al2O3 has excellent sintering properties and is important in semiconductor manufacturing processes that require high-temperature resistance and chemical inertness in a plasma environment. In this study, a comprehensive analysis of the chemical characteristics, physical properties, crystal structure, and dispersion stability of three commercially available Al2O3 powders was conducted. The aim was to provide a technological foundation for selecting and utilizing appropriate Al2O3 powders in practical applications. All powders exhibited α-Al2O3 as the main phase, with the presence of beta-phase Na2O-11Al2O3 as the secondary phase. The highest Na+ ion leaching was observed in the aqueous slurry state due to the presence of the secondary phase. Although the average particle size difference among the three powders was not significant, distinct differences in particle size distribution were observed. ALG-1SH showed a broad particle size distribution, P162 exhibited a bimodal distribution, and AES-11 displayed a uniform unimodal distribution. Highconcentration Al2O3 slurries showed differences in viscosity due to ion release when no dispersant was added, affecting the electrical double-layer thickness. Polycarboxylate was found to effectively enhance the dispersion stability of all three powders. In the dispersion stability analysis, ALG-1SH exhibited the slowest sedimentation tendency, as evidenced by the low TSI value, while P162 showed faster precipitation, influenced by the particle size distribution.

Although many attempts have been made to solve the atmospheric diffusion equation, there are many limits that prevent both solving it and its application. The causes of these impediments are primarily due to both the partial differentiation term and the turbulence diffusion coefficient. In consideration of this dilemma, this study aims to discuss the methodology and cases of utilizing a passive air sampler to increase the applicability of atmospheric dispersion modeling. Passive air samplers do not require pumps or electric power, allowing us to achieve a high resolution of spatial distribution data at a low cost and with minimal effort. They are also used to validate and calibrate the results of dispersion modeling. Currently, passive air samplers are able to measure air pollutants, including SO2, NO2, O3, dust, asbestos, heavy metals, indoor HCHO, and CO2. Additionally, they can measure odorous substances such as NH3, H2S, and VOCs. In this paper, many cases for application were introduced for several purposes, such as classifying the VOCs’ emission characteristics, surveying spatial distribution, identifying sources of airborne or odorous pollutants, and so on. In conclusion, the validation and calibration cases for modeling results were discussed, which will be very beneficial for increasing the accuracy and reliability of modeling results.

Understanding the dispersion of xenon isotopes following a nuclear test is critical for global security and falls within the remit of both the Comprehensive Nuclear-Test-Ban Treaty (CTBT) and the International Noble Gas Experiment (INGE). This paper aims to show if it is possible to discriminate the source of xenon releases based on the atmospheric dispersion of xenon isotopes using HYSPLIT. Using ORIGEN and SERPENT simulations, four released scenarios are defined with four different fractionation times (i.e., 1 hour, 1 day, 10 days, and 30 days) after a 1kt TNT equivalent 235U explosion event. These time-delayed release scenarios were selected to certify the possibility of mis-determining xenon release source. We use the Lagrangian dispersion model for atmospheric dispersion to predict the concentration distribution of xenon isotopes under each scenario. The model allows us to better understand how these isotopes would distribute over time and space, offering valuable data for real-world detection efforts. To our knowledge, there have been no researches on the analysis of xenon isotopic ratios considering atmospheric dispersion. In this work, we focused on the atmospheric dispersion using HYSPLIT to characterize the xenon isotopic ratios from nuclear tests. In addition, we compared the xenon isotopic ratios obtained from the atmospheric dispersion with those from ORIGEN calculations, which would be helpful to discriminate the source of the xenon releases.

해상공사에서 발생하는 부유사는 해수의 탁도를 증가시키고 광량을 감소시켜 해양생물에 악영향을 미치므로 해양환경영향평 가에서 중요한 요소이다. 하지만 평가에 적용되는 인자에 대한 공식적인 자료의 부족과 평가자의 능력에 따라 그 영향이 달리 평가되고 있다. 따라서 본 연구에서는 해역이용영향평가센터에서 검토한 3년간(2012–2014)의 매립, 준설, 외곽시설물 설치 등 총 58건 사업에 대한 부유사 확산 평가에 대한 실태를 진단하고 개선방안을 제시하였다. 개선방안 제시를 위해 4가지의 평가지표(격자체계의 적정성, 원단위의 적정성, 대표입경 및 침강속도의 적정성)를 적용하였다. 각 항목별 신뢰도에 평균점수 분석결과, 격자체계는 25점, 원단위는 60점, 대표입 경은 34점 그리고 침강속도는 17점으로 평가항목에 대한 개선방안이 필요한 것으로 나타났다. 본 연구에서는 부유사 확산 평가상태에 대 한 진단 및 신뢰도 평가 결과를 활용하여 부유사 확산예측에 대한 개선방안을 제안하였다. 먼저, 부유사 발생원단위 및 대표입경별 침강 속도에 대한 공신력 있는 값이 가이드라인을 통해 제공해야 한다. 그리고 실무에선 신뢰성 향상을 위해 격자체계의 적정성과 결과의 검 증을 철저히 해야 한다.

In a nuclear facility, the base metal can be radiologically contaminated during the operation. They must be decontaminated to reduce the radiation exposure to workers before decommissioning of the nuclear facility. In order to decontaminate the nuclear facility, it is possible to apply a perfluorocarbon (PFC) based emulsion consisted of surfactant and decontamination reagent. The PFC has high resistance for the radiation decomposition, and PFC based emulsion can be easily stabilized using the ultrasonication method. During decontamination process, a dispersion stability of the emulsion affects to the decontamination performance because the decontamination reagents dispersed in the emulsion contact contaminated surface. In this study, the dispersion stability the PFC based emulsion was evaluated following the composition of the emulsion and dispersion condition such as temperature, ultrasonication time. It was confirmed that the concentration of surfactant is highly related to the dispersion stability from the result of Turbiscan analysis using the multiple light scattering method. It was also verified that the droplet size of the decontamination reagent in the stable emulsion was smaller than that in the unstable emulsion. This phenomena can be explained by the relationship between the interfacial tension and droplet size. Finally, the recovering test of the PFC from the spent PFC-based decontamination emulsion was conducted using distillation method. The distillation test was performed using vacuum distillation unit, and the distillation temperature was 80°C. From the distillation test, about 95 % of PFC was recovered by distillation. From this result, it is considered that PFC-based decontamination emulsion reduces the volume of the secondary waste.

Silver/graphene core/shell nanocomposites were synthesized through a one-step electric explosion of wire method using only silver wires and ethanol. The morphology of the graphene shell structures can be easily formed by alternating the solvent from deionized water to ethanol. Transmission electron microscopy revealed that the size of the prepared silver/graphene core/ shell nanocomposites was in the 10–110 nm range. The Raman spectra showed the formation of graphene shells on silver. A possible formation mechanism of the silver/graphene core/shell nanocomposites is proposed in this study. The crystallinity of the nanoparticles was investigated via X-ray diffraction. The graphene on the surfaces of the nanocomposites containing functional groups was analyzed through Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. Zeta potential and dynamic light scattering analyses were performed to determine the dispersion characteristics of the nanocomposites when redispersed in other solvents.

재외(在外) 한인(韓人) 즉, ‘코리안 디아스포라(Korean Diaspora)’는 한민족(韓民族) 의 혈통을 이어받은 사람들이 모국을 떠나 세계 여러 지역으로 이주하여 살아가는 한민족 ‘이산(離散)’을 의미한다. 코리안 디아스포라 미술의 가장 핵심적 개념은 ‘타의(他意)에 의 한 이주’라고 할 수 있다. 코리안 디아스포라 작가들의 작품을 그들이 지닌 민족적 정체성 측면에서 분류하고 분석해보면 ‘①기억(記憶), 이산의 역사 ②근원(根源), 뿌리와 정체성 ③ 정착(定着), 또 하나의 고향 ④연결(連結), 이산과 분단을 넘어’라는 네 개의 키워드로 나누 어 살펴볼 수 있다. 첫 번째, ‘기억(記憶), 이산(離散)의 역사’는 아시아의 재외 한인 이산의 역사에 대한 집단적이고도 개인적인 기억과 서사를 다룬 작품들로 나타난다. 자발적이 아닌 타의(他意)에 의한 이주, 원치 않고 준비되지 않은 이산(離散)의 아프고 고통스러운 기억(記憶)이 코리안 디아스포라 미술의 첫 번째 정수(精髓)이다. 두 번째, ‘근원(根源), 뿌리와 정체성’은 해외 한인 동포들이 겪고 있는 정체성에 관한 것 이다. 대부분의 재외한인 동포는 민족적으로는 한민족에 속하지만 국가적으로는 다른 나라의 국적을 갖고 있다. 재일동포의 경우에는 일본으로의 귀화를 종용 당하거나 한국 국적을 취득 하기도 하지만, 이도저도 아닌 ‘조선적’이라는 무국적 상태를 지속하고 있는 이들도 있다. 혈 통에 따른 국적과 거주지에 따른 국적의 불일치라는 이중적 상황과 현지에서 소수자로서 살 면서 당하는 차별과 부조리함은 슬프고 서러운 상황일 수밖에 없다. 한반도를 떠나 이주를 시작한 증조부모나 조부모의 모습에서부터 부모와 가족을 그린 그림들, 자신의 자화상, 그리 고 백두산과 제주도 같은 혈통적 조국 산하의 풍경, 탈춤이나 돌잡이, 제사와 같은 풍물과 전통적 관습 등을 그린 여러 동포 작가의 작품에서는 한민족으로서의 혈통적․문화적 정체 성을 느끼게 된다. 세 번째, ‘정착(定着), 또 하나의 고향’은 아시아의 코리안 디아스포라 작가들이 조국을 떠나 언어와 문화가 다른 세상에 정착하고 적응하면서 만나게 되는 시각적 대상을 그린 작품 들을 보여준다. 또 다른 고향인 현지의 자연 풍경과 도시의 모습, 인물과 풍속, 역사와 종교 등은 그들 작품의 주제가 된다. 혈통적 조국이 아닌 거주국의 국민으로서 갖게 되는 국가․ 국토․현재에 대한 애정이 여러 작가의 작품에서 간취된다. 모든 예술은 풍토성을 띠는 것이 당연하므로 거주국의 관습과 문화의 영향을 받을 수밖에 없다. 또한 거주국 미술계의 역사와 현대미술의 상황을 직접적 혹은 간접적으로 반영한다. 네 번째, ‘연결(連結), 이산과 분단을 넘어’는 동포 작가들이 한민족으로서의 민족의식과 한반도의 문화적․정치적 현상에 대한 관심을 투영하여 그려낸 작품들이다. 세계에서 몇 안 되는 민족 분단 국가인 한반도에 사는 우리와 마찬가지로, 재외 한인 작가들에게도 남과 북의 대치 상황은 관심사일 수밖에 없다. 그래서 남한과 북한이 마주하는 대화의 자리가 자주 열 려, 분단을 극복하고 항구적인 평화체제가 확립되기를 바라는 염원을 담은 그림들이 꽤 많다. 코리안 디아스포라 작가의 미술이 이산과 분단을 뛰어넘고 한민족을 위한 축복과 번영의 매개자로서 역할을 할 수 있는 날이 오기를 기대한다.

Application of the membrane process to wastewater treatment and reuse has been increasing due to water shortage, water pollution and an increase in water demand. Membrane fouling including biofouling should be controlled to extend its application. In this study, modulation of diffusible signal factor (DSF) system, the quorum sensing (QS) system that regulates EPS formation by microorganisms, was considered as a promising option to manage biofouling. Among many DSF compounds, cis -2-Decenoic acids (CDA) was selected. The experimental results showed that, as the CDA concentration increased, the density and number of stained cells decreased. The lowest density was observed when the CDA concentration of 300 nM was applied. The EPS on membrane surface decreased with increasing concentration of CDA. The CDA dosing also affected the EPS composition. At the 300 nM CDA dose, the total EPS reduced by up to 57% and the protein fraction by 35%. This study revealed the biofilm reduction effect of CDA under various conditions for MBR sludge. The application of CDA can be adapted to control biofouling in the MBR process.

In order to extend the business viability of carbon nanotubes (CNTs), research on CNT dispersion in a solvent as well as in polymer matrix should be established. Herein, three kinds of dispersing agents, sodium deoxycholate (DOC), sodium dodecylbenzene sulfonate (NaDDBS), polyvinyl pyrrolidone (PVP), are selected and applied to quantify the dispersibility and dispersion stability of CNT aqueous dispersion. The dispersibility of CNT dispersion with the PVP, evaluated via viscosity and particle size analyses, are superior to those with the DOC and NaDDBS dispersing agents. CNT aqueous solution dispersed with PVP showed slightly higher viscosity and narrower particle size distribution than those with DOC and NaDDBS dispersing agents. In addition, the dispersion stability of CNT dispersion with the PVP, measured via lumisizer analyses, are superior to those with the DOC and NaDDBS dispersing agents. HR-TEM analysis verifies that the outstanding dispersibility and dispersion stability of CNTs in aqueous solution are due to the effect of the robust polymer wrapping of the PVP dispersing agent on the CNT surface. From the results of this study, the guidelines for the selection of the suitable dispersing agents and the systematic evaluation of dispersibility and dispersion stability of CNT dispersions can be suggested.

본 연구에서는 국내 서로 다른 지리적 특성을 갖는 지역에서 발생되는 해륙풍에 의한 항만 내 선박 대기오염물질의 항구도시 확산 범위를 규명하고자 하였다. 연구 대상 지역은 서해안(인천항 및 평택·당진항), 다도해 지역(목포항), 남해 및 동해(부산항 및 마산항), 동해 산간 지역(동해·묵호항)으로 선정하였다. 해륙풍 발생과 그로 인한 항만 내 선박에서 기인하는 대기오염물질의 확산 모사를 위하여 비선형(Non-linear) 및 비정상(Unsteady) 거동의 국지 순환풍 모사가 가능한 HOTMAC-RAPTAD 프로그램을 활용하였으며, 모사 기간은 전형적인 여름 날씨인 7월 중순으로 하였다. 그 결과, 해륙풍의 발생 특성과 항만에서 발생되는 대기오염물질의 주변 지역 확산 거동이 지역 마다 서로 다르게 나타났는데 연구 대상 항만인 인천항, 목포항, 부산항, 동해·묵호항에서 배출되는 대기오염물질은 항구로부터 각각 27~31km(서울 서쪽 일부 지역), 21~24km(무안 남부), 20~26km(김해 및 양산 인근), 22~25km(태백산맥 능선 지역)까지 영향을 끼치는 것으로 분석되었다. 따라서 본 연구에서 도출된 결과는 향후 효과적인 항만 지역 대기질과 선박 대기오염물질 관리에 있어 매우 중요한 기초 수단으로 활용 가능할 것으로 기대된다.

Oxide dispersion-strengthened (ODS) steel has excellent high-temperature properties, corrosion resistance, and oxidation resistance, and is expected to be applicable in various fields. Recently, various studies on mechanical alloying (MA) have been conducted for the dispersion of oxide particles in ODS steel with a high number density. In this study, ODS steel is manufactured by introducing a complex milling process in which planetary ball milling, cryogenic ball milling, and drum ball milling are sequentially performed, and the microstructure and high-temperature mechanical properties of the ODS steel are investigated. The microstructure observation revealed that the structure is stretched in the extrusion direction, even after the heat treatment. In addition, transmission electron microscopy (TEM) analysis confirmed the presence of oxide particles in the range of 5 to 10 nm. As a result of the room-temperature and high-temperature compression tests, the yield strengths were measured as 1430, 1388, 418, and 163 MPa at 25, 500, 700, and 900oC, respectively. Based on these results, the correlation between the microstructure and mechanical properties of ODS steel manufactured using the composite milling process is also discussed.