최근 지구온난화로 인해 발생하는 극단적인 기상현상이 빈번해짐에 따라, 사회 인프라와 건축물의 노후화로 인한 붕괴 위험이 증가 하고 있다. 이러한 문제를 해결하기 위해 본 연구는 구조물 유지보수 및 보강을 위한 고성능 숏크리트 공법을 개발하는 것을 목표로 한다. 특히, 자연섬유와 나노버블수를 혼입한 숏크리트는 콘크리트의 성능을 크게 향상시킬 수 있는 잠재력을 가지고 있다. 자연섬유 는 콘크리트의 점착력과 부착력을 높여 펌핑성과 유동성을 개선하고, 콘크리트 내부에 수분을 지속적으로 공급하여 소성수축 균열을 억제하는 효과가 있다. 이를 통해 구조물의 내구성을 증진시키며, 공용 수명을 연장하는 데 기여한다. 또한, 나노버블수는 콘크리트의 수화 반응을 촉진하여 응결 시간과 초기 강도를 크게 향상시킨다. 나노버블수는 콘크리트 혼합물 내에서 슬립 현상을 제공하여 리바 운드를 저감시키고, 시공 중 발생하는 재료 손실을 줄여 시공 효율성을 높이는 역할을 한다. 나아가, 나노버블수는 이산화탄소를 포집 하여 생성할 수 있어 탄소 배출을 줄이는 환경적 이점을 제공하며, 급결제 사용을 줄여 환경오염 감소에도 기여한다. 본 연구에서는 다양한 실험을 통해 각 변수의 영향을 분석하였다. 결론적으로, 자연섬유와 나노버블수를 혼입한 고성능 숏크리트를 통해 구조물 보수 및 보강 공사에서 비용을 절감하는 동시에, 내구성을 크게 향상시킬 수 있음을 증명하고자 한다. 이 연구 결과는 향후 다양한 구조물 유지 보수 공법에 적용될 수 있으며, 건설 산업에서 지속 가능한 기술로 자리 잡을 것으로 기대된다.

It was found in this study that fluorinated microporous carbon aerogels with enhanced hydrophobicity could be successfully prepared by direct fluorination to separate water-in-oil emulsions at high flux. The fluorinated carbon aerogel (F-CA) surface treated by the fluorination method had a water contact angle of 151.2° and could immediately absorb oil. In addition, the unique network structure of F-CA and its hydrophobicity allow surfactant-stabilized water-in-oil emulsions to be effectively and simply separated under gravity without requiring external forces such as vacuum or pressurization. The network structure of F-CAs consists of randomly connected spherical particles that form fluorinated permeation channels, which induce high flux during emulsion separation. The F-CA spherical particles have nanosized pores and high hydrophobicity, which repel and trap water droplets to increase the separation purity. Therefore, F-CA exhibited excellent performance, such as high filtrate purity (up to 99.9954%) and flux (up to 11,710 L/m2h). Furthermore, F-CA reusability was demonstrated as it did not lose its hydrophobicity and maintained its performance even after repeated use. This type of aerogel has great potential to be utilized throughout various environmental fields, including oil remediation.

An environmentally friendly and low-cost chitosan-containing polysaccharide (CP) composite ZIF-8/CP was designed and prepared based on the difficulty of separating the traditional adsorbent from the water phase. ZIF-8/CP was synthesized through in-situ growth approach. The physical, chemical and structure properties of ZIF-8/CP were determined through a series of characterization methods, including SEM, FT-IR and PXRD. The effects of touch time, pH, temperature, and coexisting ions on adsorption were assessed. In addition, kinetics, isotherms of adsorption and thermodynamics were examined. The data of isotherms for adsorption indicated that the adsorption of ZIF-8/CP on MG was similar to the Langmuir model, with a maximum adsorption capacity of 1428.57 mg/g. Moreover, the kinetic parameters were consistent with the pseudo- 2nd-order equation. Thermodynamic studies (ΔG < 0, ΔH > 0) demonstrated a heat-absorbing and spontaneous adsorption process. Our study reveals that ZIF-8/CP has good adsorption properties and environmental properties.

The production process of ultra-pure water (UPW) involves dozens of unit processes such as reverse osmosis (RO), pretreatments, membrane degasifier, and several ion exchange processes. Recently, continuous electrodeionization (CEDI) has replaced the 2-bed and 3-tower (2B3T) ion exchange process. As a result, the majority of wastewater in UPW production now comes from the RO concentrate. The important of RO in UPW production is to produce high-quality water with a low ion concentration (around 1 mg/L) for CEDI feed water. Minimizing RO concentrate is essential to reduce the wastewater produced in the UPW production process. This can be achieved by maximizing the recovery of the RO system. However, increasing the recovery is limited by the water quality of the RO permeate. To ensure high-quality permeate water, the RO system is designed with a two-pass configuration. The recovery of each pass in the RO system is limited (e.g., < 85%) due to the expected increase in permeate water concentration at higher RO feed water concentrations. Interestingly, tests using 4-inch RO modules with low concentration feed water (≤ 35 mg/L as NaCl) revealed that the permeate concentration remains almost constant regardless of the feed water concentration. This implies that the recovery of the first RO pass can be increased as long as the average feed/concentrate concentration of the second RO pass is less than 35 mg/L. According to this design criterion for the RO system, the recovery of the first and second RO pass, with a feed water concentration of 250 mg/L as NaCl, can be increased up to 94.8% and 96.0%, respectively. Compared to the conventional RO system design (e.g., 70% and 80% for the first and second RO pass) for UPW production, this maximum recovery design reduces the volume of RO feed and concentrate by up to 38.4% and 89.2%, respectively.

Change in chemical constitution of a zirconium sample treated at the simulated condition of a pressurized water reactor (water at 315°C and 15.5 MPa) was investigated using X-ray diffraction (XRD) and Raman spectroscopy. We observed swelling of the zirconium sample as well as the change in its color from silver to gray treated after the pressurized water at high temperature. On the basis of XRD and Raman data, we confirmed that the variation in composition of zirconium specimen from hexagonal Zr to monoclinic ZrO2 occurred at the simulated PWR condition. Therefore, we suggested that the oxidation of zirconium appeared due to the reaction with water at high temperature and pressure, as shown in the following reaction: Zr + 2H2O → ZrO2 + 2H2.

Bentonite, a material mainly used in buffer and backfill of the engineering barrier system (EBS) that makes up the deep geological repository, is a porous material, thus porewater could be contained in it. The porewater components will be changed through ‘water exchange’ with groundwater as time passes after emplacement of subsystems containing bentonite in the repository. ‘Water exchange’ is a phenomenon in which porewater and groundwater components are exchanged in the process of groundwater inflow into bentonite, which affects swelling property and radionuclide sorption of bentonite. Therefore, it is necessary to assess conformity with the performance target and safety function for bentonite. Accordingly, we reviewed how to handle the ‘water exchange’ phenomenon in the performance assessment conducted as part of the operating license application for the deep geological repository in Finland, and suggested studies and/or data required for the performance assessment of the domestic disposal facility on the basis of the results. In the previous assessment in Finland, after dividing the disposal site into a number of areas, reference and bounding groundwaters were defined considering various parameters by depth and climate change (i.e. phase). Subsequently, after defining reference and bounding porewaters in consideration of water exchange with porewater for each groundwater type, the swelling and radionuclides sorption of bentonite were assessed through analyzing components of the reference porewater. From the Finnish case, it is confirmed that the following are important from the perspective of water exchange: (a) definition of reference porewater, and (b) variations in cation concentration and cation exchange capacity (CEC) in porewater. For applying items above to the domestic disposal facility, the site-specific parameters should be reflected for the following: structure of the bedrock, groundwater composition, and initial components of bentonite selected. In addition, studies on the following should be required for identifying properties of the domestic disposal site: (1) variations in groundwater composition by subsurface depth, (2) variations in groundwater properties by time frame, and (3) investigation on the bedrock structure, and (4) survey on initial composition of porewater in selected bentonite The results of this study are presumed to be directly applied to the design and performance assessment for buffer and backfill materials, which are important components that make up the domestic disposal facility, given the site-specific data.

This study aims to select eggplant cultivars adaptive to the hot temperature period greenhouse climate by water consumption, and growth performance of plants and fruits of different European eggplant cultivars, including ‘Bartok (BA)’, ‘Bowie (BO)’, ‘Black Pearl (BP)’, ‘Ishbilia (I)’, ‘Mabel (M)’, ‘Vestale (VE)’ and ‘Velia (VL)’, in substrate hydroponic cultivation under hot and humid greenhouse conditions. On the 118 DAT, the leaf number and stem dry weight were highest in ‘VL’, followed by ‘M’, and there was no significant difference in leaf dry weight among cultivars. The marketable fruit number per plant was 16.4 for ‘M’, which was higher than other cultivars, and ‘VE’ and ‘VL’ were 8.5 and 8.8, respectively. The weight per fruit was low for ‘M’ at 136 g, and the highest in ‘VE’ and ‘VL’ at 332 and 281 g, respectively. There was no significant difference in fruit production per plant. In this study, ‘M’, which has high water use efficiency and a large number of fruits, and ‘VL’, which required less quantity to water consumption for producing 200 g of fruit and had a high product weight, will have excellent adaptability in the UAE greenhouse condition.

동해연안의 반폐쇄성 해역인 영일만에서 고주파해양레이더(HF-Radar)로 측정된 표층 해수유동 자료를 활용하여 1)바람과 수평 적인 해수유동 사이의 상관성을 파악하고 2)수직적으로 조밀한 간격의 층별 수온시계열 자료와 연계하여 수평적 및 수직적 해수유동의 특성을 파악하였다. 시계열 관측기간 중 영일만 해역의 전역에 걸쳐 북동풍이 우세하게 나타났을 때 표층부터 저층까지 수온의 급격한 상승이 동반되었다. 또한 표층의 장주기 해수유동에서도 풍향과 유사한 방향의 흐름이 뚜렷하게 관측되었다. 바람과 표층 해류 사이의 지 연상관 분석을 통해 영일만에 북동풍의 바람이 불기 시작하여 일정하게 지속된다면 짧은 시간(1 ~ 2시간) 내에 남서향의 표층 해류가 발 생되는 것을 확인하였다. 일평균된 장주기 표층 해류로부터 수렴과 발산을 계산하였고 이를 통해 층별 관측지점에서 발생한 두 번의 급 격한 저층수온 상승이벤트가 모두 영일만의 북동풍과 연관된 표층 해수(상대적 고온수)의 수렴(침강) 현상으로 인해 나타난 것으로 판단 하였다.

국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛･냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.