When decommissioning a nuclear power plant, the structure must be made to a disposable size. In general, the cutting process is essential when dismantling a nuclear power plant. Mainly, thermal cutting method is used to cutting metal structures. The aerosols generated during thermal cutting have a size distribution of less than 1 μm. The contaminated structures are able to generate radioactive aerosols in the decommissioning. Radioactive aerosols of 1 μm or less are deposited in the respiratory tract by workers’ breathing, causing the possibility of internal exposure. Therefore, workers must be protected from the risk of exposure to radioactive aerosols. Prior knowledge of aerosols generated during metal cutting is important to ensure worker safety. In this study, the physical and chemical properties of the aerosol were evaluated by measuring the number and mass concentrations of aerosols generated when cutting SUS304 and SA508 using the laser cutting method. High-resolution aerosol measuring equipment (HR-ELPI+, DEKATI) was used to measure the concentration of aerosols. The HR-ELPI+ is an impactor-type aerosol measuring equipment that measures the aerosol number concentration distribution in the aerodynamic diameter range of 6 nm to 10 um in real-time. And analyze the mass concentration of the aerosol according to the diameter range through the impactor. ICP-MS was used for elemental mass concentration analysis in the aerosol. Analytical elements were Fe, Cr, Ni and Mn. For the evaluation of physical and chemical properties, the MMAD of each element and CMAD were calculated in the aerosol distribution. Under the same cutting conditions, it was confirmed that the number concentration of aerosols generated from both materials had a uni-modal distribution with a peak around 0.1 um. CMAD was calculated to be 0.072 um for both SUS304 and SA508. The trend of the CMAD calculation results is the same even when the cutting conditions are changed. In the case of MMAD, it was confirmed that SUS304 had an MMAD of around 0.1 μm in size for only Fe, Cr and Mn. And SA508, Fe, Cr, Ni and Mn were all confirmed to have MMAD around 0.1 μm in size. The results of this study show that a lot of aerosols in the range of less than 1 μm, especially around 0.1 μm in size, are generated when metal is cut using laser cutting. Therefore, in order to protect the internal exposure of workers to laser metal cutting when decommissioning NPPs, it is necessary to protect from nano-sized aerosols beyond micron size.

Bentonite containing >50wt% montmorillonite is being considered as a buffer material in a deep geological repository to dispose of high-level radioactive wastes (HLRW). Bentonite is considered a buffer material because of its exceptional properties such as high swelling capacity, low hydraulic conductivity, and high radionuclide sorption capacity. The bentonite buffer can be exposed to heat from the radioactive decay of HLRW and to groundwater. Water in bentonite buffer can be converted to steam under elevated temperature and pressure conditions. Previous studies reported contrasting results showing that steam treatment could decrease the swelling capacity due to changes in the surface properties from hydrophilic to hydrophobic or could not change. The contrasting results were probably because different studies used different experimental conditions and methods. Therefore, the effect of steam treatment on the bentonite properties is still unclear. The purpose of this study is to determine how the bentonite properties change after steam treatment, in particular swelling and hydrophilic properties. Two types of bentonite were used for steam treatment and analysis; Gyeongju Ca-bentonite (KJ- II) and Wyoming Na-bentonite (GCL-B). Steam treatment was performed at 150°C in an oven for various periods (7, 30, 60, and 90 days). Free swell test, X-ray fluorescence (XRF) analysis, surface-area measurement (BET), thermal gravimetric analysis (TGA), cation exchange capacity (CEC), and water uptake test were performed on steam-treated bentonite for various periods and raw bentonite. After steam treatment, some properties of steam-treated bentonite changed when compared to raw bentonite. Free swell index, which means the swelling capacity, decreased significantly as the results of previous studies. CEC and BET surface area values depended on the bentonite type. For Wyoming Na-bentonite, in which the dominant interlayer cation is a monovalent cation, CEC and BET surface area values were increased. On the other hand, Gyeongju Ca-bentonite, in which the dominant interlayer cation is a divalent cation, has no change in the above two properties. Results of XRF analysis, TGA, and water uptake test showed that these properties of both bentonites did not change after steam treatment. The results of this study confirmed that steam treatment affected the swelling and physicochemical properties of bentonite, in particular Na-bentonite. Further studies will focus on the surface properties of bentonite to investigate whether the surface properties have changed from hydrophilicity to hydrophobicity, or whether the montmorillonite structure has changed.

목적: 상분리가 일어나지 않는 실리콘하이드로겔 콘택트렌즈(silicone hydrogel contact lens, SH-CL) 제조에 적합한 실리콘 모노머의 구조를 알아보고자 한다. 방법 : HEMA(2-hydroxyethyl methacrylate)와 세 종류의 실리콘 모노머, TRIM[3-(trimethoxysilyl)propyl methacrylate, Aldrich], TEMA[2-(trimethylsilyloxy)ethyl methacrylate, TCI], TMMA[(trimethylsilyl) methacrylate, Aldrich]를 활용하여 완전몰드로 SH-CL를 제조하였다. 함수율과 UV-VIS spectrophotomter 를 이용한 광투과율, TGA 분석을 통한 열적안정성 등의 물리적 특성과 FT-IR 분석을 통한 화학적 특성을 알아 보았다. 결과 : 동일한 양의 TRIM, TEMA, TMMA를 사용하여 제작한 SH-CL의 광투과율은 각각 92%, 86%, 80%로 측정되었으며, 함수율은 TRIM을 사용한 SH-CL에서 39.3%로 가장 높게 나타났다. FT-IR 분석 결과 세 종류의 SH-CL 모두 silicone monomer와 HEMA의 중합반응이 잘 이루어졌음을 확인할 수 있었고, TGA 분석을 통해 TRIM monomer의 sol-gel 반응 유무를 확인할 수 있었다. 결론 : Sol-gel 반응에 적합한 구조를 가지고 있어 상분리가 일어나지 않아 투명하고, Si에 극성 작용기인 methoxy기가 연결되어 있는 TRIM monomer가 SH-CL 제조에 적합한 구조임을 확인할 수 있었다.

본 연구에서는 채소정식을 위한 정식기에 사용하는 생분해성 포트를 개발하기 위하여 생분해성 첨가제의 비율에 따라 포트의 물성 및 식물의 생장 차이를 구명하였다. 본 실험에 사용된 생분해포트의 주원료는 크라프트지와 신문고지였고, 생분해성 포트는 주 배합비에서 내첨첨가제의 함량을 주원료 대비 각 3%, 5%로 제조하였다. 본 실험에서 8주 육묘 후 포트의 물리적 특성과 첨가제에 따른 변화를 알아보기 위해 포트의 인장강도, 두께, 무게 등을 조사하였다. 생분해성 첨가제가 함유된 포트와 일반 PE포트에 식물 생장도 비교하였다. 2주차에서 5주차에는 매주 배추의 생육조사를 진행했고, 5주차에서 8주차에는 고추생육조사를 진행하였다. 식물의 생장은 뿌리신선중(g), 지상부 시선중(g), 옆 장(cm), 옆 폭(cm)등을 측정하였다. 생분해성 포트에서의 식물 생장은 플라스틱 포트에 비해 생육이 저조하게 나타났다. 생분해성 포트의 무게와 두께는 첨가제 함량에 따라 낮은 상관성을 보였지만, 인장강도의 경우 차이를 보여 내첨제의 비율에 따라 생육에 영향을 미치는 것으로 나타났다. 그러나 첨가제는 무게와 두께에는 영향을 미치지 않아 포트의 생분해 능력에는 영향이 없는 것으로 판단된다. 본 연구는 생분해성 식물 포트 개발의 기초자료가 될 것으로 기대된다.

PURPOSES : This study was conducted to evaluate the physical properties of micro-foamed asphalt binders. Surfactants and water-soluble anti-stripping agent were used to improve the performance of the foamed asphalt binder, and a domestically developed foamed asphalt generator was used for the micro-foamed asphalt binder. The results of this study can be used as technical data for the domestic application of foamed asphalt technology. METHODS : To evaluate the physical properties of the micro-foamed asphalt binder, basic properties such as penetration, viscosity, softening point, and ductility were evaluated. Additionally, DSR and BBR tests were performed to confirm the change in the performance grade of the micro-formed asphalt binder when using surfactants, water-soluble anti-stripping agent, and water. RESULTS : Of the results of evaluating the physical properties of the micro-foamed asphalt binder containing surfactant confirmed that the kinematic viscosity was reduced by 12.5% compared with the straight asphalt binder, which indirectly confirmed that compaction is possible even at low temperatures when producing the asphalt mixture. In addition, the PG grade of straight asphalt and micro-foamed asphalt binder was PG 64-22. This result indicates that surfactants, water-soluble anti-stripping agent, and water did not significantly affect the PG grade of the asphalt binder. CONCLUSIONS : The properties of the micro-foamed asphalt binder were confirmed through the evaluation of the physical and rheological properties of the foamed asphalt binder to which the surfactant and water-soluble anti-stripping agent were applied, and we determined that it can be used as a technical material for the revitalization of Korean foamed asphalt technology.

고형분 70% 아크릴수지를 합성하기 위해 n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA) 및 acetoacetoxyethyl acrylate(AAEA)와 caprolactone acrylate(CLA)를 사용하여 공중합체의 유리전이온도(Tg)를 50 ℃로 조정하여 합성하였으며, 합성한 아크릴수지의 점도와 분자량은 수산기가(OH values)의 증가에 따라 증가되었다. 높은 고형분의 아크릴수지 합성에 적합한 반응개시제는 di-tert-amyl peroxide 이었으며, 최적의 합성조건은 반응 개시제 5 wt%, 연쇄이동제 4 wt%, 반응온도 140 ℃에서 적하시간은 4시간이었다. 합성수지의 구조는 FT-IR과 1H-NMR spectroscopy로 확인하였고, 수평균 분자량은 1900~2600, 분자량 분포도 1.4~2.1을 얻었다. 합성한 아크릴수지와 무황변성 폴리이소시아네이트인 hexamethylene diisocyanate trimer(Desmodur N-3300)의 NCO/OH 당량비를 1.2/1.0으로 조절하여 아크릴-우레탄 투명도료를 제조하였다. 도료의 물리적 특성으로 점도, 부착성, 건조시간, 가사시간, 연필경도 및 광택을 비교 검토한 결과 부착성, 건조시간, 가사시간, 연필경도 및 광택이 양호한 결과를 나타내었고, 특히 CLA를 10 % 도입한 도료는 부착성이 우수하고 낮은 점도와 높은 경도를 나타내었다.

PURPOSES : In general, a high-performance concrete construction method is a method of loading mixed cement and other materials on a mobile mixer equipped with a concrete plant. However, the construction cost is high because the unit cost of the mixed cement is very high and the equipment usage fee of the mobile mixer is also high. To compensate for these drawbacks, a cellular spray concrete method was developed. This is a highly functional customized concrete construction method in which admixtures are added to high-flow concrete with cellular (air bubbles) added at the site and constructed through spraying. METHODS : Field workability evaluation using cellular concrete was carried out using a spray method in 2017 and an anti-foaming agent in 2018. The test construction section was set as a new road-pavement construction site. After construction, strength, durability characteristics, and void analysis were performed to compare the construction methods. The results of laboratory tests under optimal conditions were also compared to the on-field results. By comparing the indoor mixing and the on-field results, we analyzed whether there were any problems concerning the performance expression. The economic feasibility at the initial construction stage was analyzed by comparing the existing and the cellular concrete construction methods in terms of material cost and equipment usage fee. RESULTS : In the case of cellular spray concrete, construction through spraying is cumbersome, and the need to additionally use large equipment such as a pump car and compressor constitutes a disadvantage. However, the most relevant feature is that it can be constructed not only on the floor, but also on a slope. In the case of cellular concrete with an antifoaming agent, it was possible to quickly produce high-performance concrete using on-site remixing equipment. By supplying materials to the pouring surface using a conveyor, smooth construction and construction in narrow spaces were also possible. CONCLUSIONS : The cellular concrete method allows the immediate on-site production of high-performance concrete, and it is possible to selectively apply spray construction, antifoaming agent construction, etc.

In this study, the polyurethane resin was synthesized by applying PTMG and DMBA of different composition ratios for the synthesis of water-dispersible polyurethane used in wound coating resin. The varying properties of the synthesized water-dispersible polyurethane were measured through tensile strength, elongation, and abrasion resistance analysis. As for the tensile strength measurement result according to the PTMG content, the sample with the highest reaction molar ratio was measured as 1.08 kgf/mm2 and the elongation was measured as 520%. As for the tensile strength result according to the DMBA content, the sample with the highest reaction molar ratio was measured as 0.51 kgf/mm2, and the elongation was measured as 435%. The degree of surface destruction by the abrasion resistance measurement was visually confirmed through SEM.

목적 : 본 연구는 실리콘과 친수성 단량체를 포함하는 기능성 실리콘 콘택트렌즈를 제조하기 위해 Isobornyl Methacrylate 및 2-(Trifluoromethyl)styrene을 사용하여 물리적, 광학적 특성을 분석하였다. 방법 : 고분자의 중합은 실리콘 모노머와 친수성 단량체인 DMA(N,N-Dimethylacrylamide), 가교제인 EGDMA (Ethylene glycol dimethacrylate) 그리고 개시제인 AIBN(azobisisobutyronitrile)을 사용하여 공중합하였다. 첨 가제는 Isobornyl Methacrylate와 2-(Trifluoromethyl)styrene를 각각 사용하였으며, 제조된 콘택트렌즈의 물 성 변화를 알아보기 위해 분광투과율, 굴절률, 산소투과율, 인장강도 등을 측정하였다. 결과 : 제조된 친수성 콘택트렌즈의 산소투과율은 실리콘의 영향으로 33.22×10-11(cm2/s)(mlO2/ml×mmHg) 으로 나타났다. 첨가제인 Isobornyl Methacrylate의 양이 증가함에 따라 굴절률은 다소 향상되었고, 분광투과율은 첨 가제 양에 따라 가시광선 영역에서 약 15% 향상되어 투명한 콘택트렌즈가 제조되었다. 또한 2-(Trifluoromethyl) styrene의 첨가량에 따라 인장강도는 약 45% 향상된 것으로 나타났다. 결론 : 본 연구를 통해 제조된 실리콘 콘택트렌즈는 콘택트렌즈의 기본적인 물성을 만족시키면서 고산소투과성 을 가지며, Isobornyl Methacrylate 및 2-(Trifluoromethyl)styrene는 각각 상용성과 내구성을 향상시키는 것 으로 나타나 콘택트렌즈 재료로 다양하게 활용될 수 있을 것으로 판단된다.

The objective of this study was to determine chemical compositions affecting the physical and thermal properties of the textured vegetable protein (TVP). The 14 commercial TVPs were pulverized, followed by analyzing their morphology, chemical composition, water absorption index (WAI) and water solubility index (WSI) (for the pulverized and original TVPs), solubility, swelling power, melting property, and hardness. All TVPs showed the rough surface with irregular cracks and pores and the porous structure with varied pore sizes. WAI was positively correlated to moisture and crude protein contents and negatively correlated to the total carbohydrate content. WSI and solubility were directly and reversely influenced by the crude ash and total carbohydrate contents and the crude protein and total starch contents, respectively. The swelling power and melting temperature of TVPs did not significantly affect chemical compositions. Melting enthalpies increased with crude ash content, while decreased with the total starch content. The hardness of the rehydrated TVPs was enhanced with their crude ash and total carbohydrate contents, whereas reduced with their crude protein and total starch contents. Overall, the yield and texture of the rehydrated TVP could be modulated with the crude protein and ash contents of TVP.