PURPOSES : The purpose of this study was to evaluate the performance of a titanium dioxide (TiO2) asphalt surface treatment agent for reducing NOx on the roadside at laboratory and full scales. METHODS : To verify the NOx reduction performance of TiO2 and silicon-based resin-applied surface treatment agents at the lab scale, a bed flow photo reactor test (ISO standard) and a mixed tank photo reactor test designed to apply real-scale construction materials were conducted. Subsequently, the full-scale NOx reduction performance was verified using a full-scale demonstration facility, and the field construction capability of the TiO2 asphalt surface treatment agent was verified through actual road site application. RESULTS : The bed flow photoreactor and mixed tank photoreactor methods showed the same trend in the NOx removal performance. Evaluation of the NOx removal performance of the TiO2 surface treatment agent revealed that the NO removal rate was approximately 13% at the laboratory scale and 15% at full scale. CONCLUSIONS : Through this study, it was determined that the asphalt surface treatment agent applied with TiO2 will have a sufficient NOx reduction effect in an actual road site. In the future, it will be necessary to analyze the continuity of the effect according to traffic volume through continuous monitoring in the field.

Removing CO2 gas to address the global climate crisis is one of the most urgent agendas. To improve the CO2 adsorption ability of activated carbon, nitrogen plasma surface treatment was conducted. The effect of nitrogen plasma treatment on the surface chemistry and pore geometry of activated carbon was extensively analyzed. The porosity and surface groups of the activated carbon varied with the plasma treatment time. By plasma treatment for a few minutes, the microporosity and surface functionality could be simultaneously controlled. The changed microporosity and nitrogen groups affected the CO2 adsorption capacity and CO2 adsorption selectivity over N2. This simultaneous surface etching and functionalization effect could be achieved with a short operating time and low energy consumption.

실버 페이스트는 상대적으로 낮은 열처리로 공정이 가능하기 때문에 전자 소자 응용분야에서 유용한 전극 재료이다. 본 연구에서는 은 페이스트 전극에 대기압 플라즈마 제트를 이용하여 전극 표면을 처리 했다. 이 플라즈마 제트는 11.5 kHz 작동 주파수에서 5.5 ~ 6.5 kV의 고전압을 사용하여 아르곤 분 위기에서 생성되었다. 플라즈마 제트는 대기압에서 수행함으로써 인쇄 공정에 더 유용할 수 있다. 플라즈 마 처리시간, 인가된 전압, 가스유량에 따라 전극의 표면은 빠르게 친수성화 되었으며 접촉각의 변화가 관 찰되었다. 또한, 대면적 샘플에서 플라즈마 처리 후 접촉각의 편차가 없었는데, 이는 기판의 크기에 관계없 이 균일한 결과를 얻을 수 있었다는 것을 의미한다. 본 연구의 결과는 대면적 전자소자의 제조 및 향후 응 용 분야에서 적층 구조를 형성하는데 매우 유용할 것으로 기대된다.

This study investigated variables for improving adhesive strength using laser surface treatment when bonding dissimilar materials using adhesives. adhesive strength analysis was performed for CFRP and Al6061 by laser irradiation intensity, and surface roughness was measured to analyze the related results. In the case of CFRP, the adhesive strength was good when the surface was not treated. In the case of Al6061, the adhesive strength was 25 MPa when the surface was treated with 20W, the maximum output of the laser surface treatment equipment, and the adhesive strength was improved by 125% compared to the untreated specimen. In addition, by measuring the surface roughness in the experiment, it was confirmed that the higher the surface roughness, the better the adhesive strength.

PURPOSES : The effects of strontium cations on the strength of hydrated cement composites as well as the morphology and chemical composition changes of cement hydrates due to strontium treatment are investigated in this study. Subsequently, the potential of a strontiumbased aqueous solution as a near-surface treatment method for hydrated cement composites is evaluated. METHODS : To supply strontium cations to a hydrated cement composite, a 30% strontium nitrate aqueous solution was used. Cement paste (w/c = 0.4) specimens were prepared and cured in the 30% strontium nitrate aqueous solution, which allows the strontium ions to penetrate into the specimen and treat the near-surface region. Compressive and flexural strength tests were performed on both specimens treated by the strontium ions and untreated specimens cured in deionized water, and the test results were compared. To investigate the changes in the morphology and chemical compositions of the cement hydrates due to the treatment, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analyses were performed. RESULTS : The results of the strength tests indicate that both the compressive and flexural strengths of the specimens cured in the 30% strontium nitrate aqueous solution improved significantly compared with the specimens cured in deionized water for the same duration. In particular, the strontium nitrate aqueous solution shows greater improvement in terms of the flexural strength compared with the compressive strength. The maximum penetration depth of strontium into the hydrated cement composite is 5 mm during the first 7 d of immersion and increases to 6.5 mm during the subsequent 14 d. The SEM results show that the microstructure of the hydrated cement composite is densified by the strontium nitrate aqueous solution treatment. The EDS results show that morphology and chemical compositions of the cement hydrates are altered. This implies that the strontium cations can be combined with C–S–H and C–S–A–H phases to form new types of hydrates. CONCLUSIONS : The experimentally results show that the strength of hydrated cement composites can be improved by modifying their near-surface regions via the strontium cation penetration technique. This implies that the strontium-based aqueous solution exhibits high potential for the maintenance and rehabilitation of concrete structures.

The SLA 3d printer is the first of the commercial 3D printer. The 3D printed output is printed hanging on the bed that move to the upper position. Sandblasted bed is used to prevent layer shift. If sandblasting is wrong, the 3D printed output is layer shifted. For this reason, 3D printer manufacturing companies inspect the bed surface. However, the sandblasted surface has variety of irregular shapes and craters, so it is difficult to establish a quality control standard. To solve problems, this paper presents a standardized sandblasting histogram and threshold. We present a filter that can increase the classification rate.

AlSi10Mg alloys are being actively studied through additive manufacturing for application in the automobile and aerospace industries because of their excellent mechanical properties. To obtain a consistently high quality product through additive manufacturing, studying the flowability and spreadability of the metal powder is necessary. AlSi10Mg powder easily forms an oxide film on the powder surface and has hydrophilic properties, making it vulnerable to moisture. Therefore, in this study, AlSi10Mg powder was hydrophobically modified through silane surface treatment to improve the flowability and spreadability by reducing the effects of moisture. The improved flowability according to the number of silane surface treatments was confirmed using a Carney flowmeter. In addition, to confirm the effects of improved spreadability, the powder prior to surface treatment and that subjected to surface treatment four times were measured and compared using s self-designed recoating tester. The results of this study confirmed the improved flowability and spreadability based on the modified metal powder from hydrophilic to hydrophobic for obtaining a highquality additive manufacturing product.

In the flux used in the batch galvanizing process, the effect of the component ratio of NH₄Cl to ZnCl₂ on the microstructure, coating adhesion, and corrosion resistance of Zn-Mg-Al ternary alloy-coated steel is evaluated. Many defects such as cracks and bare spots are formed inside the Zn-Mg-Al coating layer during treatment with the flux composition generally used for Zn coating. Deterioration of the coating property is due to the formation of AlClx mixture generated by the reaction of Al element and chloride in the flux. The coatability of the Zn-Mg-Al alloy coating is improved by increasing the content of ZnCl2 in the flux to reduce the amount of chlorine reacting with Al while maintaining the flux effect and the coating adhesion is improved as the component ratio of NH4Cl to ZnCl2 decreases. Zn-Mg-Al alloy-coated steel products treated with the optimized flux composition of NH₄Cl•3ZnCl₂ show superior corrosion resistance compared to Zn-coated steel products, even with a coating weight of 60 %.

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.

The molybdenum cup and molybdenum pin, which are the main materials of the molybdenum electrode used for the LCD BLU CCFL electrode, have not been developed in Japan and all of them are imported and used from Japan, is giving a competitive burden. In this research, to develop the manufacturing technology of molybdenum pin used for CCFL electrode of LCD BLU, development of linear processing technology, development of molybdenum wire surface treatment technology, development of wire cutting technology, production of molybdenum pin, design and fabrication of JIG and Fixture for inspection, molybdenum pin prototyping and analysis, and development of 100% molybdenum pin inspection technology. In this paper, especially, research on surface treatment technology of molybdenum wire is treated.