Total dissolved solids (TDS) 제거에 이용되는 이온교환수지는 컬럼에 충진시켜 사용하게 되는데, 이온교환 과정 에서 이온성 물질과 이온교환수지의 충분한 접촉시간을 필요로 한다. 본 연구에서는 이온교환수지의 분체화를 통하여 짧은 접촉시간으로도 높은 TDS 제거 성능을 보이는 이온교환수지의 특성을 연구하였다. 흐름성 등을 고려한 분체의 최적 크기는 100 μm 이상임을 확인하였고, 250~500 μmd와 100~250 μm 크기의 최대 분쇄 수율은 각각 67.3%와 36.9%였다. 또한 100~500 μm 크기의 분쇄 수율은 분쇄 시간 2분에서 87.1%로 나타났다. 회분식(batch) 실험 조건에서 250~500 μm 크기의 분체가 95%와 99%의 제거율에 도달하는 시간은 분쇄 전(non-pulverized) 이온교환수지에 비해 각각 1.82배와 1.96배 더 빨랐 다. 100~250 μm 크기의 분체는 각각 15.9배와 6.18배 더 빨랐다. 컬럼 테스트의 경우 분쇄 전 이온교환수지는 총 1.74 g, 250~500 μm 크기의 분체는 1.83 g, 100~250 μm 크기의 분체는 1.63 g의 NaCl을 제거하였다. 분체의 크기가 작아질수록 용 량(capacity)이 약간 감소한 것으로 나타났다. 결과적으로 분체화된 이온교환수지를 사용하는 것이 접촉시간 대비 높은 TDS 제거 성능을 얻을 수 있는 방법임을 확인하였다.

Spent ion exchange resins have been generated during the operation of nuclear facilities. These resins include radioactive nuclides. It is needed to fabricate them into a stable form for final disposal. Cement solidification process is a useful method for the fabrication of them into a waste form for final disposal. In this study, proper conditions for the fabrication of them into a stable waste form were determined using the cement solidification process. In-drum waste forms were then produced at the conditions, where the stability of representative samples was evaluated for final disposal. The samples were satisfied to the Waste Acceptance Criteria for low and intermediate level radioactive waste disposal sites. This result can be utilized to derive optimal conditions for the fabrication of spent ion exchange resins into a final disposal form.

The homogeneity of radioactive spent ion exchange resins (IERs) distribution inside waste form is one of the important characteristics for acceptance of waste forms in long-term storage because heterogenous immobilization can lead to the poor structural stability of waste form. In this study, the homogeneity of metakaolin-based geopolymer waste form containing simulant IERs was evaluated using a laser-induced breakdown spectroscopy (LIBS) and statistical approach. The cation-anion mixed IERs (IRN150) were used to prepare the simulant spent IERs contaminated by non-radioactive Cs, Fe, Cr, Mn, Ni, Co, and Sr (0.44, 8.03, 6.22, 4.21, 4.66, 0.48, and 0.90 mg/g-dried IER, respectively). The K2SiO3 solution to metakaolin ratio was kept constant at 1.2 and spent IERs loading was 5wt%. For the synthesis of homogeneous geopolymer waste form, spent IERs were mixed with K2SiO3 solution and metakaolin first, and then the fresh mixture slurry was poured into plastic molds (diameter: 2.9 cm and height: 6.0 cm). The heterogeneous geopolymer waste form was also fabricated by stacking two kinds of mixtures (8wt% IERs loading in bottom and 2wt% in top) in one mold. Geopolymers were cured for 7d (1d at room temperature and 6d at 60°C). The hardened geopolymers were cut into top, middle, and bottom parts. The LIBS spectra and intensities for Cs were obtained from the top and bottom of each part. Cs was selected for target nuclide because of its good sensitivity for measurement. Shapiro-Wilk test was performed to determine the normality of LIBS data, and it revealed that data from the homogeneous sample is normal distribution (p-value = 0.9246, if p-value is higher than 0.05, it is considered as normal distribution). However, data from the heterogeneous sample showed abnormal distribution (p-value = 7.765×10-8). The coefficient of variation (CoV) was also calculated to examine the dispersion of data. It was 31.3% and 51.8% from homogeneous and heterogeneous samples, respectively. These results suggest that LIBS analysis and statistical approaches can be used to evaluate the homogeneity of waste forms for the acceptance criterion in repositories.

When exposed to different types of bacteria in the oral cavity, denture based resins are prone to bacteria attachment. The purpose of this study was to investigate the physical, biological, and antimicrobial properties of denture base resins coated with Peony extract (200, 400, and 600 μg/mL). Specifically, the surface properties (microhardness, contact angle, and color change of the coated specimens), cell cytotoxicity (measured using MTT assay), and antimicrobial activity (against S. mutans (Streptococcus mutans) and C. albicans (Candida albicans) using a growth inhibition assay) were evaluated. The polyphenol content was measured using ultraviolet-visible (UV-vis) spectrometry. The experimental groups (specimens coated with Peony extract) and a control group (specimens coated without Peony extract) were statistically compared using a one-way analysis of variance and Tukey’s post-hoc tests. No statistically significant differences in surface properties or cell cytotoxicity were observed, which demonstrated their biocompatibility. Conversely, a statistically significant difference in antimicrobial activity was observed between the experimental and control groups after 48 h. This confirms the antimicrobial activity of the denture base resin coated with Peony extract and demonstrates that it is a promising dental material for preventing stomatitis.

This study aimed to remove uranium (U(VI)) ions from sulfate-based acidic soil-washing effluent using the ion-exchange method. For effective ion exchange of U(VI) ions under acidic conditions, one chelate resin (Purolite S950) stable under low pH conditions and two anion-exchange resins (Ambersep 400 SO4 and 920U SO4) used in sulfuric acid leaching systems were selected. The exchange performance of the three selected ion-exchange resins for U(VI) ions was evaluated under various experimental conditions, including ion-exchange resin dosages, pH conditions, reaction times, and reaction temperatures. U(VI) ion exchange was consistent with the Langmuir model and followed pseudo-second-order kinetics. Thermodynamic experiments revealed that the U(VI) ion exchange by the ion-exchange resins is an endothermic and spontaneous process. On the other hand, U(VI) ions was effectively desorbed from the ion-exchange resins using 0.5 M H2SO4 or Na2CO3 solution. Overall, on the basis of the results of the present study, we propose that Purolite S950, Ambersep 400 SO4, and Ambersep 920U SO4 are ion-exchange resins that can be practically applied to effectively remove U(VI) ions from sulfate-based acidic soil-washing effluents.

본 연구에서는 가교제인 붕산과 아크릴 수지 바인더에 삼인산(3 인산), 피트산(6 인산) 또는 폴 리인산암모늄(10 인산)을 혼합하여 인계 난연 코팅액을 제조하였다. 제조된 인계 난연 코팅액을 부직포에 각각 코팅하여 높은 난연 효과를 얻었다. 이렇게 제조된 난연성 부직포를 연기밀도기준시험(ASTM E662), 산소한계지수기준시험(ISO E622), 수직연소기준시험(UL 94)을 이용하여 평가하였다. 그들의 난연 효과는 phosphate 그룹의 수에 의해 영향을 받았으며, 천연 또는 합성 바인더 수지에 관계없이 그 효과는 ammonium polyphosphate > phytic acid > triphosphate의 순서로 나타났다. 천연 탄화수소 화합물도 바인더 수지의 난연성을 결정하기 위해 조사되었다. 그 결과 천연 탄화수소 바인 더 수지가 난연성 부직포 제조에 사용될 수 있음을 보여주었다.

전자 및 화학 산업의 초순수 생산 및 원자력 발전소의 부식 제어를 위해 이온교환 수지탑의 성능 파악이 필수적이다. 따라서 본 연구에서는 4종의 H 및 ETAH 형 양이온 교환수지가 채워진 양이온 및 혼상 이온교환수지탑에 미량의 NaCl를 포함하는 에탄올아민(ETA) 및 암모니아(NH3) 용액을 주입하여 양이온 파과특성을 조사하였다. 조사 결과, 주성분인 ETAH+ 및 NH4 +와 달리, 미량성분인 Na+는 (이론적교환용량의 3배 이상) 시험기간 동안 수지탑 출구에서 파과 및 오버슈팅 현상이 나타나지 않았다. H형 수지탑의 파과현상은 ETAH+ 및 NH4 +가 순서대로 일어났고, 오버슈팅은 NH4 +가 파과할때 ETAH+에 대해서 발생했다. 파과영역의 너비로 결정되는 상대적 선택도는 NH4 +가 ETAH+보다 최대 51.5 % 더 높았다. 유입수 Na+ 농도가 높을수록, 선택도는 감소하고 오버슈팅 현상은 증가하였다. 이온교환 수지의 고유 특성을 개선하여 감소시킬 수 있는 Na+ 누출은, ETAH형에서 높았고 4종의 양이온수지에 대해 동일하지 않은 것으로 조사되었다.

최근 국내 구조물들의 노후화가 진행됨에 따라 구조물 보강과 관련된 연구에 대한 관심이 높아지고 있다. FRP보강은 노후화가 진행되어 성능이 저하된 구조물을 보강하는데 사용되며 주로 유리섬유 및 탄소섬유를 사용한다. 그러나 이 두 가지의 섬유는 경제적으로나 환경적으로나 나쁜 점이 있다. 따라서 본 연구에서는 친환경적이고 내열성이 우수한 현무암 섬유를 구조 용 보강재로 제시하고자 하였다. 또한 본 연구에서는 현무암 섬유에 가장 적합한 수지를 찾기 위하여 에폭시, 폴리에스테르 및 비닐에스테르를 함침 하였다.그 결과, 에폭시 수지를 사용하였을 때 가장 높은 인장 강도 및 탄성계수를 보였으며 전단강도 및 전단탄성계수가 타 수지에 비하여 50%정도 높게 측정되었다. 현무암섬유와 탄소, 유리 섬유의 물성을 비교한 결과 인장강도는 CFRF의 약 60%정도이나 GFRP보다 30%정도 높게 나타내었다.

This study examines the role of the nano- and micro-particle ratio in dispersion stability and mechanical properties of composite resins for SLA(stereolithography) 3D printing technology. VTES(vinyltriethoxysilane)-coated ZrO2 ceramic particles with different nano- and micro-particle ratios are prepared by a hydrolysis and condensation reaction and then dispersed in commercial photopolymer (High-temp) based on interpenetrating networks(IPNs). The coating characteristics of VTES-coated ZrO2 particles are observed by FE-TEM and FT-IR. The rheological properties of VTEScoated ZrO2/High-temp composite solution with different particle ratios are investigated by rheometer, and the dispersion properties of the composite solution are confirmed by relaxation NMR and Turbiscan. The mechanical properties of 3Dprinted objects are measured by a tensile test and nanoindenter. To investigate the aggregation and dispersion properties of VTES-coated ZrO2 ceramic particles with different particle ratios, we observe the cross-sectional images of 3D printed objects using FE-SEM. The 3D printed objects of the composite solution with nano-particles of 80 % demonstrate improved mechanical characteristics.

With the significant increase in spent ion-exchange resin generation, to meet the requirements of Waste Acceptance Criteria (WAC) of the Wolsong disposal facility in Korea, blending is considered as a method for enhancing disposal options for intermediate level waste from nuclear reactors. A mass balance formula approach was used to enable blending process with an appropriate mixing ratio. As a result, it is estimated around 44.3% of high activity spent resins can be blended with the overall volume of low activity spent resins at a 1:7.18 conservative blending ratio. In contrast, the reduction of high activity spent resins is considered a positive solution in reducing the amount of spent resins stored. In an economic study, the blending process has been proven to lower the disposal cost by 10% compared to current APR1400 treatment. Prior to commencing use of this blending method in Korea, coordinated discussion, and safety and health assessment should be undertaken to investigate the feasibility of fitting this blending method to national policy as a means of waste predisposal processing and management in the future.

고성능 복합재료는 기존의 소재에 비해 우수한 기계적 물성을 보이며 특히 높은 비강도를 보인다. 복합재료 의 매트릭스로 사용되는 에폭시 수지는 이들의 독특한 화학반응성, 경화반응에 사용되는 경화제의 적절한 조합으로 많은 다양한 특성을 보일 수 있다. 본고에서는 고성능 복합재 구조물 제작에 사용되어온 에폭시 수지 시스템을 소개 하고자 한다. 필라멘트 와인딩 공법에 사용되는 에폭시 수지와 프리프레그 제조에 사용되는 에폭시 수지의 조성과 특 성을 중심으로 설명하였다.