Domestic commercial low- and intermediate-level radioactive waste storage containers are manufactured using 1.2 mm thick cold-rolled steel sheets, and the outer surface is coated with a thin layer of primer of 10~36 μm. However, the outer surface of the primer of the container may be damaged due to physical friction, such as acceleration, resonance, and vibration during transportation. As a result, exposed steel surfaces undergo accelerated corrosion, reducing the overall durability of the container. The integrity of storage containers is directly related to the safety of workers. Therefore, the development of storage containers with enhanced durability is necessary. This paper provides an analysis of mechanical properties related to the durability of WC (tungsten carbide)-based coating materials for developing low- and intermediate-level radioactive waste storage containers. Three different WC-based coating specimens with varied composition ratios were prepared using HVOF (high-velocity oxy-fuel) technique. These different specimens (namely WC-85, WC-73, and WC-66) were uniformly deposited on cold-rolled steel surfaces ensuring a constant thickness of 250 μm. In this work, the mechanical properties of the three different WCbased coaitng materials evaluated from the viewpoints of microstructure, hardness, adheision force between substrate and coating material, and wear resistance. The cross-sectional SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) images revealed that elements W (tungsten), C (carbon), Ni (nickel), and Cr (chromium) were uniformly distributed within the each coating layers which was approximately 250 μm thick. The average hardness values of HWC-85 and HWC-73 were found to be 1,091 Hv (Vickers Hardness) and 1,083 Hv, respectively, while the HWC-66 exhibited relatively lower hardness value of 883 Hv. This indicates that a higher WC content results in increased hardness. Adhesion force between and substrates and coating materials exceeded 60 MPa for all specimens, however, there were no significant differences observed based on the tungsten carbide content. Furthermore, a taber-type abrasion tester was used for conducting abrasion resistance tests under specific conditions including an H-18 load weight at 1,000 g with rotational speed set at 60 RPM. The abrasion resistance tests were performed under ambient temperatures (RT: 23±2°C) as well as relative humidity levels (RH: 50±10%). Currently, the ongoing abrasion resistance tests will include some results in this study.

This research measured the change in mechanical characteristics of a sample obtained by finishing a metal coating to an engineering plastic manufactured using a 3D printer to satisfy both lightweight and quality characteristics. High-Temp material, which can be applied to space thermal environments with large temperature fluctuations, was applied as the engineering plastic material, and Stereolithography(SLA) method, which has relatively higher precision than Fused Film Fabrication(FFF) method, was selected as the manufacturing method. Electroless & electroplating were performed by metal coating on the surface to satisfy the characteristics of products requiring electrical conductivity. Tensile and bending tests were conducted to verify a change in the mechanical characteristics of a sample completed with a metal coating, and an adhesion test of the metal coating was also added.

대표적인 짚공예 가운데 하나인 맥간공예(혹은 보릿대 조각공예)는 표면이 매끄럽고 광택이 나는 보릿대를 활용하고 있으며 최근에 국내뿐 아니라 해외로 전파되고 있다. 보릿대 표면의 줄기 방향과 나란한 미세 줄무늬는 맥간공예 작품에 입체감과 각도에 따른 색감을 갖게 한다. 하지만 아직까지 보릿대 표면의 형상과 물성이 체계적으로 분석되지 않은 실정이다. 본 연구에서는 고해상도 실체현미경과 고해상도 3차원 X-ray 현미경을 이용하여 보릿대의 미세구조를 이미징할 뿐만 아니라 보릿대의 물접촉각과 인장 강도를 측정하여 보릿대의 재질을 분석하였다. 이를 통해 보릿대 최외각에 존재하는 4-6 μm 너비의 미세요철에 의한 줄무늬, 소수성을 띈 겉면, 친수성을 띈 속면, 그리고 60 MPa 정도의 줄기 방향의 항복강도를 갖는 보릿대 특성을 확인하였다. 본 연구에서 제시한 분석 방법으로 볏짚을 비롯한 다른 짚공예에 사용되는 짚 재료의 특성을 파악한다면 짚의 재질을 최대로 활용한 새로운 짚공예로 이어질 것이다.

In this study, surface roughness and interfacial defect characteristics were analyzed after forming a high-k oxide film on the surface of a prime wafer and a test wafer, to study the possibility of improving the quality of the test wafer. As a result of checking the roughness, the deviation in the test after raising the oxide film was 0.1 nm, which was twice as large as that of the Prime. As a result of current-voltage analysis, Prime after PMA was 1.07 × 10 A/cm2 and Test was 5.61 × 10 A/cm2, which was about 5 times lower than Prime. As a result of analyzing the defects inside the oxide film using the capacitancevoltage characteristic, before PMA Prime showed a higher electrical defect of 0.85 × 1012 cm2 in slow state density and 0.41 × 1013 cm2 in fixed oxide charge. However, after PMA, it was confirmed that Prime had a lower defect of 4.79 × 1011 cm2 in slow state density and 1.33 × 1012 cm2 in fixed oxide charge. The above results confirm the difference in surface roughness and defects between the Test and Prime wafer.

To thoroughly analyze the mechanical properties and surface conditions of HF50S carbon fibers, the tensile properties, surface morphology, surface chemical element, surface energy, sizing agent properties, and Naval Ordnance Laboratory (NOL) ring of their composites were characterized. Furthermore, the aforementioned properties were exhaustively compared with those of T1000G carbon fibers. The results showed that the tensile strength, modulus, and elongation of the HF50S carbon fibers were 6638 MPa, 297 GPa, and 2.2%, respectively, thus demonstrating that the mechanical properties of the HF50S carbon fibers were on par with those of the T1000G carbon fibers, in addition, the coefficient of variation (Cv) indices of HF50S carbon fiber were below 3%, indicating good stability. The HF50S carbon fibers have a smooth surface without grooves, which is analogous to that of the T1000G carbon fibers prepared by the typical dry jet–wet spinning process. The main component of the sizing agent of the HF50S carbon fibers is an epoxy resin, which is also used for the preparation of epoxy matrix composites. Because the HF50S carbon fiber surface has greater O and N contents than the T1000G carbon fiber surface, the HF50S carbon fibers have more active functional groups and higher surface activity. The surface energy of the HF50S carbon fibers is 30.13 mJ/m2, which is higher than that of the T1000G carbon fibers (28.42 mJ/m2). Owing to the higher strength and surface activity of the HF50S carbon fibers than those of the T1000G carbon fibers, the strength and strength conversion of NOL ring based on the former are slightly higher than those of that prepared using the latter.

피마자 기반 수성 폴리우레탄(CPUD)을 얻기 위해 무 변성 피마자유 (CO) 와 투명 필름을 얻기 위해 이소포론 디이소시아네이트(IPDI)를 사용했다. 유연성을 증가시키기 위해 폴리프로필렌글리콜 (PPG)의 혼합 효과를 분석하였다. 또한, 사슬연장제로 에틸렌다이아민(EDA)을 사용했다. 각각 피마자유 함유에 따른 변화와 사슬연장제 변화에 따른 인장강도, 연신율 내마모성을 측정했다. 피마자유 함유가 많은 시료의 인장강도가 1.112kgf/㎟, 연신율 88%로 나타났으며, 사슬연장제 함유가 많은 시료의 인장 강도가 3.33kgf/㎟, 연신율 99%로 측정되었다. 표면강도는 SEM을 통해 육안으로 확인하였다.

제 4 차 산업혁명이 일어남에 따라 각국의 정부와 기업들은 보다 환경친화적인 정책과 기술 개발에 힘쓰고 있다. 배기가스 배출과 소음이 거의 없는 전기차 및 수소차의 개발, 그리고 이를 보편화 하기 위한 정부의 정책 등 기존의 경제, 산업 구조를 친환경적으로 바꾸려는 시도가 많이 이루어지고 있다. 최근 여러 환경문제를 해결하기 위해 각종 유해 가스 흡착 및 폐수 처리용으로 활성탄을 많이 사용하고 있으나 흡착질의 특성에 따라 요구되는 표면 특성이 다르기 때문에 수요에 걸맞는 활성탄의 개발이 점차 요구되고 있는 실정이다. 따라서 본 연구에서는 친수성 유기물 제거에 유리한 활성탄을 개발하고자 C-O, C-O-C, C=O 및 O=C-O 등과 같은 친수성 작용기를 질산처리 방법을 통해 활성탄 표면에 효과적으로 도입하는 연구를 진행하였다. 질산을 활용하여 끓는점 및 다양한 농도 조건에서 활성탄을 환류, 개질하였고, 이를 세척 후 고온에서 탄화시켜 활성탄의 표면을 개질하였다. 제조된 개질활성탄은 활성탄의 비표면적, mesopore 및 micropore 의 함량을 알기 위하여 BET 를 이용하여 측정하였고, 4 M 120 ℃에서 개질한 결과 가장 높은 792.22 m2g-1 으로 확인되었다. 또한 제조된 활성탄의 표면 및 기공 특성 변화를 확인하기 위해 SEM, XPS, EDX, BET 등의 분석을 실시하였으며 질산 처리 정도에 따른 특성 변화에 대해 비교 고찰하였다.

Graphene, a new material with various advantageous properties, has been actively used in various fields in recent years. Applications of graphene oxide are increasing in combination with other materials due to the different properties of graphene oxide, depending on the number of single and multiple layers of graphene. In this study, single-layer graphene oxide and multi-layer graphene oxide are spray coated on polystyrene, and the physicochemical properties of the coated surfaces are characterized using SEM, Raman spectroscopy, AFM, UV-Vis spectrophotometry, and contact angle measurements. In singlelayer graphene oxide, particles of 20 μm are observed, whereas a 2D peak is less often observed, and the difference in surface height increases according to the amount of graphene oxide. Adhesion increases with an increase in graphene oxide up to 0.375 mg, but decreases at 0.75 mg. In multi-layer graphene oxide, particles of 5 μm are observed, as well as a 2D peak. According to the amount of graphene oxide, the height difference of the surface increases and the adhesive strength decreases. Both materials are hydrophilic, but single-layer graphene oxide has a hydrophilicity higher than that of multi-layer graphene oxide. We believe that multi-layer graphene oxide and single-layer graphene oxide can be implemented based on the characteristics that make them suitable for application.

In this study, nitric acid oxidation with varied treatment temperature and time was conducted on the surfaces of polyacrylonitrile- based ultrahigh modulus carbon fibers. Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and surface tension/dynamic contact angle instruments were used to investigate changes in surface topography and chemical functionality before and after surface treatment. Results showed that the nitric acid oxidation of ultrahigh modulus carbon fibers resulted in decreases in the values of the crystallite thickness Lc and graphitization degree. Meanwhile, increased treating temperature and time made the decreases more obviously. The surfaces of ultrahigh modulus carbon fibers became much more activity and functionality after surface oxidation, e.g., the total surface energy of oxidized samples at 80 °C for 1 h increased by 27.7% compared with untreated fibers. Effects of surface nitric acid oxidation on the mechanical properties of ultrahigh modulus carbon fibers and its reinforced epoxy composites were also researched. Significant decreases happened to the tensile modulus of fibers due to decreased Lc value after the nitric acid oxidation. However, surface treatment had little effect on the tensile strength even as the treating temperature and processing time increased. The highest interfacial shear strength of ultrahigh modulus carbon fibers/epoxy composites increased by 25.7% after the nitric acid oxidation. In the final, surface oxidative mechanism of ultrahigh modulus carbon fibers in the nitric acid oxidation was studied. Different trends of the tensile strength and tensile modulus of fibers in the nitric acid oxidation resulted from the typical skin–core structure.

In the geochemical field, the chemical speciation of hexavalent uranium (U(VI)) has been widely investigated by performing measurements to determine its luminescence properties, namely the excitation, emission, and lifetime. Of these properties, the excitation has been relatively overlooked in most time-resolved laser fluorescence spectroscopy (TRLFS) studies. In this study, TRLFS and continuous-wave excitation–emission matrix spectroscopy are adopted to characterize the excitation properties of U(VI) surface species that interact with amorphous silica. The luminescence spectra of U(VI) measured from a silica suspension and silica sediment showed very similar spectral shapes with similar lifetime values. In contrast, the excitation spectra of U(VI) measured from these samples were significantly different. The results show that distinctive excitation maxima appeared at approximately 220 and 280 nm for the silica suspension and silica sediment, respectively.

방오도료는 수중에서 사용 되는 시설물의 원치 않은 해양 생물 부착으로 인해 생기는 다양한 문제점을 해결 하기위해 사용되어 왔다. 하지만 최근, 방오도료에 사용되는 방오제가 해양생태계에 악영향을 미치는 것이 밝혀지면서 사용을 줄이거나 대체되고 있는 상황이다. 주로 사용되는 대체제로써 방오제를 사용하지 않거나 방출하지 않는 파울 릴리즈 방오 도료가 주목 받고 있다. 이 연구에서는, 파울 릴리즈 도료로 하이드 록실 말단 폴리 디메틸 실록산과 산화철 안료를 포함하는 접착 필름을 제작하였다. 방오 시험을 위해 박테리아로는 Escherichia coli와 미세조류 종으로 Navicula annexa 와 Nitzschia 종을 사용하여 수행하였다. 이 연구 결과로, 표면이 조금 더 거칠 때 물리적인 미생물 부착 방지를 통해 더 나은 방오 성능을 나타냄을 알 수 있었다.

산업분야에서는 다양한 용액을 대상으로 분리, 정제, 농축 등의 공정이 필요하며, 분리막이 그 역할을 잘 수행해 오고 있다. 반면, 처리 대상 용액이 강산을 함유하고 있는 경우, 대부분의 분리막은 산에 취약하기 때문에 사용이 제한적일 수밖에 없다. 현재 내산성 분리막으로 상용화 되고 있는 분리막은 투과속도가 낮은 문제점을 갖고 있다. 이에, 투과속도가 높 은 폴리아마이드 분리막에 내산성을 부여하기 위한 접근 방법을 모색하기 위한 기초 자료로 본 총설에서는 폴리아마이드 분 리막이 산성 용액 노출 시 표면성질 및 투과특성이 변화하는 원인과 기작에 대해 살펴보고자 한다.

Oxide-dispersion-strengthened (ODS) alloy has been developed to increase the mechanical strength of metallic materials; such an improvement can be realized by distributing fine oxide particles within the material matrix. In this study, the ODS layer was formed in the surface region of Zr-based alloy tubes by laser beam treatment. Two kinds of Zr-based alloys with different alloying elements and microstructures were used: KNF-M (recrystallized) and HANA-6 (partial recrystallized). To form the ODS layer, Y2O3-coated tubes were scanned by a laser beam, which induced penetration of Y2O3 particles into the substrates. The thickness of the ODS layer varied from 20 to 55 μm depending on the laser beam conditions. A heat affected zone developed below the ODS layer; its thickness was larger in the KNF-M alloy than in the HANA-6 alloy. The ring tensile strengths of the KNF-M and HANA-6 alloy samples increased more than two times and 20–50%, respectively. This procedure was effective to increase the strength while maintaining the ductility in the case of the HANA-6 alloy samples; however, an abrupt brittle facture was observed in the KNF-M alloy samples. It is considered that the initial microstructure of the materials affects the formation of ODS and the mechanical behavior.