Infrared radiation accounts for approximately 50% of the solar spectrum. Specifically, the near-infrared (NIR) spectrum, ranging from 760 nm to 2500 nm, is primarily responsible for solar heat gain, increasing indoor temperatures and reducing heating and cooling efficiency. To address this issue, we developed a highly transparent thermo-shielding flexible film that maintains a high transmittance of the visible region (T = 80%) while reducing the transmittance of the NIR region (T ≈ 0%). NIR-absorbing indium tin oxide (ITO) nanocrystals were coated onto polyethylene terephthalate (PET) films, and both films were sandwiched to improve the NIR absorption properties and protect the nanocrystal film layer. The fabricated films were applied to a model house and decreased the indoor temperature by approximately 8°C. Our study demonstrates that energy consumption can be reduced by ITO nanocrystal-coated flexible films, with potential implications for the smart window and mobility markets.

The arrival of the 5G era has made electromagnetic pollution a problem that needs to be addressed, and flexible carbon-based materials have become a good choice. In this study, wet continuous papermaking technology was used to prepare carbon fiber paper (CFP) with a three-dimensional conductive skeleton network; Molybdenum disulfide ( MOS2)/ iron (Fe) @ carbon fiber paper-based shielding material was prepared by impregnating and blending molybdenum disulfide/iron ( MOS2/Fe) phenolic resin MOS2/ Fe@ CFP. The morphology, structure, electrical conductivity, mechanical properties, hydrophobicity, and electromagnetic shielding properties of the composite were characterized. The results show that the three-dimensional network structure based on a short carbon fiber paper-based conductive skeleton and the synergistic effect of the MOS2 dielectric wave absorbing agent and Fe magnetic wave absorbing agent have good electromagnetic shielding performance. Conduct electromagnetic shielding simulation using HFSS software to provide options for the structural design of CFP. The electromagnetic shielding performance of CFP reaches 70 dB, and the tensile strength reaches 34.39 MPa. Based on the mechanical properties, the compactness of carbon fiber paper is ensured. The lightning damage model test using CST software expands the direction for the use of carbon fiber paper. In summary, MOS2/ Fe @CFP with excellent shielding performance has great application prospects in thinner and lighter shielding materials, as well as high sensitivity, defense and military equipment.

In the current study, the epoxy material was mixed with 10%, and 30% weight percent carbon material as filler in different thicknesses (1 cm, 1.5 cm, and 2 cm). Transmission electron microscope (TEM) measurements showed the average size of the nano-carbon was 20 nm with a standard deviation of 5 nm. The morphology of samples was examined using scanning electron microscopy (SEM), which showed the flatness of the epoxy surface, and when the content of carbon increases, the connection between the epoxy array and carbon increases. The compression test indicates the effect of nano-size on enhancing the mechanical properties of the studied samples. To survey the shielding properties of the epoxy/carbon composites using gamma-rays emitted from Am-241, Ba-133, Cs-137, Co-60, and Eu-152 sources, which covered a wide range of energies from 0.059 up to 1.408 MeV, the gamma intensity was measured using the NaI (Tl) detector. The linear and mass attenuation coefficients were calculated by obtaining the area under each peak of the energy spectrum observed from Genie 2000 software in the presence and absence of the sample. The experimental results obtained were compared theoretically with XCOM software. The comparison examined the validity of experimental results where the relative division rate ranged between 0.02 and 2%. Also, the measurement of the relative division rate between linear attenuation coefficients of microand nano-composites was found to range from 0.9 to 21% The other shielding parameters are calculated at the same range of energy, such as a half-value layer (HVL), mean free path (MFP), tenth-value layer (TVL), effective atomic number (Zeff), and the buildup factors (EBF and EABF). The data revealed a consistent reduction in the particle size of the shielding material across various weight percentages, resulting in enhanced radiation shielding capabilities. The sample that contains 30% nano-carbon has the lowest values of TVL (29.4 cm) and HVL (8.85 cm); moreover, it has the highest value of the linear attenuation coefficient (LAC), which makes it the best in its ability to attenuate radiation.

탄소섬유 강화 플라스틱 (Carbon fiber reinforced plastics, CFRP)은 고함량의 탄소섬유 (Carbon fiber, CF)와 고분자로 이루어진 복합재료로서, 뛰어난 기계적 성능으로 항공우주, 자동차, 토목 등 다 양한 산업 분야에서 사용되고 있다. 하지만 사용량 증가에 따른 폐기물의 환경문제와 추출한 재활용 탄소섬유 (Recycled carbon fiber, rCF)의 적용 가능 분야의 한계로 인해 재활용이 제한적인 실정이 다. 본 연구에서는 rCF와 CF 혼입 시멘트계 전자파 복합재를 제작하여 그 성능을 비교 분석하기 위 한 실험을 수행하였다. 구성재료는 시멘트, 잔골재, 고성능 감수제를 사용하였으며, 비교 분석을 위해 CF와 rCF를 각각 6 mm, 12 mm 길이를 0.1, 0.3, 0.5, 1.0 wt.% 함량으로 사용하였다. 전자파 복합 재의 흡수 성능 향상을 위해 각각 다른 함량의 다층 구조를 형성하였으며, 전자파 투과를 낮은 함량에 서 높은 함량 방향이 되도록 측정을 진행하였다. 전자파 차폐성능은 재령 28일 이후 네트워크 분석기 를 사용하여 자유 공간에서 측정하였으며, C-band (4~8 GHz)와 X-band (8~12 GHz) 주파수 영역 에서의 반사율과 투과율을 각각 측정하였다.

Recent advancements in electronic devices and wireless communication technologies, particularly the rise of 5G, have raised concerns about the escalating electromagnetic pollution and its potential adverse impacts on human health and electronics. As a result, the demand for effective electromagnetic interference (EMI) shielding materials has grown significantly. Traditional materials face limitations in providing optimal solutions owing to inadequacy and low performance due to small thickness. MXene-based composite materials have emerged as promising candidates in this context owing to their exceptional electrical properties, high conductivity, and superior EMI shielding efficiency across a broad frequency range. This review examines the recent developments and advantages of MXene-based composite materials in EMI shielding applications, emphasizing their potential to address the challenges posed by electromagnetic pollution and to foster advancements in modern electronics systems and vital technologies.

Metals are recognized as electromagnetic interference (EMI) shielding materials owing to their high electrical conductivity. However, the need for light and flexible EMI shielding materials has emerged, owing to the heavyweight and inflexible nature of metals. Carbon nanotube (CNT)/polymer composites have been studied as promising flexible EMI shielding materials because of their lightweight nature due to the low density of CNTs and their high electrical conductivity. CNTs evenly dispersed in the polymer form an electrically conductive network, and the aspect ratio of the CNTs, which are one-dimensional nanofillers, is an important factor affecting electrical conductivity. In this study, we prepared three types of multi-walled carbon nanotubes (MWNTs) with different aspect ratios and fabricated polydimethylsiloxane (PDMS)/MWNT composites. Subsequently, the electrical conductivities and electrical percolation thresholds of the three PDMS/MWNT composites with different MWNT aspect ratios were measured to analyze the behavior of electrically conducting network formation according to the aspect ratio. Furthermore, the total EMI shielding effectiveness of each composite was determined to evaluate the effect of the MWNT aspect ratio on the EMI shielding. Reflection and absorption of electromagnetic wave were measured for the PDMS/MWNT composite with the largest aspect ratio to analyze the EMI shielding mechanism of the composite. Additionally, the effects of the MWNT content on the conductivity and EMI shielding performance were examined. The results provide valuable guidance for designing polymer MWNT composites with good electrical conductivity and EMI shielding performance under different aspect ratios of MWNTs.

Environmental regulations of the International Maritime Organization (IMO) are getting stricter, and the demand for replacing the fuel of ships with eco-friendly fuels instead of heavy oil in the shipbuilding and marine industries is increasing. Among eco-friendly fuels, LNG (liquefied natural gas) is currently the most popular fuel. This is because it is an alternative that can avoid the IMO's environmental regulations by replacing fuel. In PART 1, as a basic study of laser welding of high manganese steel materials, a fiber laser bead-on-plate experiment was conducted using nitrogen protective gas, and the effect of each factor on the penetration shape was analyzed through cross-sectional observation. In PART II, argon and helium shielding gases, not the nitrogen shielding gas used in PART I, were tested under the same experimental conditions and the effect of the shielding gas on penetration during laser welding was conducted.

Environmental regulations of the IMO (International Maritime Organization) are becoming more and more conservative. In order to respond to IMO, the demand for replacing the fuel of ships with eco-friendly fuels instead of conventional heavy oil is increasing in the shipbuilding and offshore industries. Among eco-friendly fuels, LNG (Liquefied Natural Gas) is currently the most popular fuel. LNG is characteristically liquefied at -163 degrees, and at this time, its volume is reduced to 1/600, so it is transported in a cryogenic liquefied state for transport efficiency. A tank for storing this should have sufficient mechanical/thermal performance at cryogenic temperatures, and among them, high manganese steel is known as a material with high price competitiveness and satisfying these performance. However, high manganese steel has a limitation in that the mechanical performance of the filler metal is lower than that of the base metal called ‘under matching’. In this study, to overcome this limitation, a basic study was conducted to apply the fiber laser welding method without filler metal to high manganese steel. To obtain efficient welding conditions, in this study, bead-on-plate welding was performed by changing the fiber laser welding speed and output using helium shielding gas, and the effect of each factor on the penetration shape was analyzed through cross-sectional observation.

Preparation of advanced functional materials from agricultural waste by eco-friendly processing route is inevitable for sustainable development. This work demonstrates the development of carbon/silica (C/SiO2) and carbon/silicon carbide (C/ SiC) composite foam monoliths of low thermal conductivity, high EMI shielding performance and reasonable compressive strength from rice husk. The C/SiO2 and C/SiC composite foams are obtained by carbonization and subsequent carbothermal reduction, respectively, of rice husk–sucrose composites consolidated by filter-pressing rice husk powder dispersed in sucrose solutions of various concentrations (300–600 g L− 1). The amorphous nature of silica in C/SiO2 and the presence of β-SiC in C/SiC are evidenced from XRD and TEM analysis. The compressive strength and thermal conductivity are depending on the foam density which is tailored by sucrose solution concentration. The compressive strength in the ranges of 0.32–1.67 and 0.19–1.19 MPa are observed for C/SiO2 and C/SiC foams, respectively, with density in the ranges of 0.26–0.37 and 0.18–0.29 g cm− 3. The C/SiO2 and C/SiC exhibited thermal conductivity in the ranges of 0.150–0.205 W m− 1 K− 1 and 0.165–0.431 W m− 1 K− 1, respectively. The C/SiO2 and C/SiC composite foams show absorption dominated EMI shielding effectiveness in the ranges of 18–38.5 dB and 20–43.7 dB, respectively. The inherent pore channels and corrugated surface structure in rice husk, electrically conducting carbon and dielectric SiO2 and SiC contribute to the total EMI shielding.

Due to stricter environmental regulations of the International Maritime Organization(IMO), the number of ships fueled by Liquefied Natural Gas(LNG) is rapidly increasing. The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code) limits the material of tanks that can store cryogenic substances such as LNG. Among the materials listed in the IGC Code, ASTM A553M-17 has been recently adopted as a material for LNG fuel tank projects because of its excellent mechanical properties at cryogenic temperatures. In shipyards, this material is being used to build tanks through Flux Cored Arc Welding (FCAW). However, there is a problem that magnetization occurs during welding and there is a big difference in welding quality depending on the welding position. In order to overcome this problem, this study intends to conduct basic research to apply laser welding to ASTM A553M-17 material. In this study, a study on penetration (HAZ depth, Penetration) and welding defects during fiber laser welding according to three types of shielding gases(nitrogen, argon, and helium) was conducted. To this end, a Bead on plate(BOP) experiment was performed under four fiber laser conditions(Power, Speed) for each shielding gas and welding defects caused by the use of the shielding gas were compared through cross-sectional observation, and the penetration depth was analyzed.

Thermal and wind panels are installed on offshore oil and gas platforms to protect personnel, equipment and structures. However, in general, panels are designed and manufactured through trial and error based on performance tests. For this reason, it is difficult to develop and design a heat sink in the Korean shipbuilding and offshore equipment industry due to the lack of performance test data and limited experience. In this study, the experimental results performed to verify the performance of the thermal and wind panels were analyzed, and the characteristics and performance characteristics of the thermal and wind panels were investigated. The conclusions drawn from this study will be useful in terms of the design and development of shielding.

Lightweight and flexible electromagnetic interference (EMI) shielding materials are in great demand for wearable EMI device. In the present work, lightweight and flexible carbon nanotube (CNT)/ferroferric oxide ( Fe3O4) composite film was made through a feasible chemical vapor deposition process for CNT film synthesis, followed by a hydrothermal reduction process for Fe3O4 coating. In the as-prepared composite, CNT film and Fe3O4 particles work as conductive skeleton and strong magnetic particle, respectively. The as-prepared composite film shows a novel EMI shielding effectiveness (SE) of 91 dB in the X-band, a small thickness of 0.09 mm and a low density of 0.86 g/cm3, which is superior to most of the carbonbased EMI materials.

Electromagnetic interference (EMI) shielding is an important issue in modern daily life due to the increasing prevalence of electronic devices and their compact design. This study estimated EMI-shielding effect (EMI-SE) of small (8–14×17 mm) Hanji (Korean traditional paper) doped with carbon nanotubes (CNTs) and compared to Hanji without CNT using 2H (92.1 MHz) and 23Na (158.7 MHz) nuclear magnetic resonance (NMR) peak area data obtained from 1 M NaCl in D2O samples in capillary tubes that were wrapped in the Hanji samples. The simpler method of using the variation of reflected power and tuning frequency by inserting the sample into an NMR coil was also tested at 242.9, 158.7, and 92.1 MHz. Overall, EMI shielding was relatively more effective at the higher frequencies. Our results validated that NMR methods to be useful to evaluate EMI-SE, particularly for small, flexible shielding materials, and demonstrated that EMI shielding by absorption is dominant in Hanji mixed with CNT.

The microstructure, flexural properties, electrical conductivity, thermal conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites filled with multi-walled carbon nanotubes (CNTs), exfoliated graphite nanoplatelets (xGnPs) and CNT-xGnP hybrid filler were investigated. The EMI SE of the CNT-xGnP hybrid composite was higher than 25 dB at 100 MHz while that of the xGnP based composite was almost zero. The flexural modulus of the CNT-xGnP based epoxy composite continuously increased to 3.32 GPa with combined filler content up to 10 wt% while that of the CNT based epoxy composites slightly decreased to 1.96 GPa at 4 wt% CNT, and dropped to 1.57 GPa at 5 wt% loading, which is lower than that of epoxy. The CNT and CNT-xGnP samples had the same EMI SE at the same surface resistivity, because samples with the same surface conductivity have the same amount of the charge carriers.

목 적 : MRI는 부분 영역을 자세히 영상화하는 검사이다. 그럼에도 불구하고 인체에 위해 한 RF를 전신에 주고 있다. 따라 서 본 연구에서는, 부분 촬영 시 RF를 차단할 수 있는 방호복을 자체 제작하여 적용함으로써, 전신에 인가되는 RF로 인해 발생할 수 있는, 온도 상승으로 인한 인체의 위해를 방지하고자 하였다. 대상 및 방법 : 연구 방법은, RF 차단 섬유의 성능을 평가하기 위해, 원통형 fluid phantom을 이용하여 phantom 실험을 시 행한 후 그 결과를 바탕으로 방호복을 제작하여 무릎에 임상실험을 시행하였다. 영상 획득은, 3.0T 초전도 자기공명영상장 치와 32 channel anterior 코일을 사용하여, T1 WI, T2 WI, T2 FS 영상을 획득하였고, 영상 측정 프로그램을 이용하여 영상의 소거 정도와 aliasing artifact 발생 정도를 측정하였으며, 대응 표본 T 검정을 이용하여 적용 전, 후에 따른 유의한 차이가 있는지 비교 평가하였다. 결 과 : 실험 결과, phantom 실험의 경우, 영상의 소거 정도와 aliasing artifact 발생 정도 모두 적용 전보다 후가 평균 98.94% 감소하였다. 이는, RF 차단 섬유가 RF를 완벽히 차단한다는 것으로, RF가 인체와 반응하지 못했다는 것을 의미한 다. 이와 같은 결과는 임상실험 결과를 통해서도 알 수 있는데, 임상실험 또한, phantom 실험과 마찬가지로 영상의 소거 정도와 aliasing artifact 발생 정도 모두 적용 전보다 후가 평균 95.89% 감소하였다. 결과를 종합해 보면, 본 연구의 방호복이 RF를 완벽히 차단하여 인체에 유해한 온도 상승을 제어할 수 있는 가장 직접적인 개선 방안이다. 결 론 : 본 연구에서 제시한 RF 방호복은, RF와 인체와의 상호작용을 원천적으로 차단할 수 있어 규정된 SAR의 초과 우려가 없으며, 이는 곧 온도 상승으로 인해 인체에 발생할 수 있는 위해를 감소시킬 수 있다. 따라서 저자들은 주자장이 높아지고 있는 현 상황에서 본 연구가 제시한 RF 방호복이, 부분 촬영 시 전신에 인가되는 RF로 인해 발생할 수 있는 인체의 위해를 줄일 수 있는 최적의 대안이라고 생각한다.

Biodegradable epoxy (B-epoxy) was prepared from diglycidyl ether of bisphenol A and epoxidized linseed oil. The mechanical properties of B-epoxy composites reinforced with multi-walled carbon nanotubes (MWCNTs/B-epoxy) were examined by employing dynamic mechanical analysis, critical stress intensity factor (KIC) tests, and impact strength tests. The electromagnetic interference shielding effectiveness (EMI-SE) of the composites was evaluated using reflection and absorption methods. Mechanical properties of MWCNTs/B-epoxy were enhanced with an increase in the MWCNT content, whereas they deteriorated when the MWCNT content was >5 parts per hundred resin (phr). This can likely be attributed to the entanglement of MWCNTs with each other in the B-epoxy due to the presence of an excess amount of MWCNTs. The highest EMI-SE obtained was ~16 dB for the MWCNTs/B-epoxy composites with a MWCNT content of 13 phr at 1.4 GHz. The composites (13 phr) exhibited the minimum EMI-SE (90%) when used as shielding materials at 1.4 GHz. The EMI-SE of the MWCNTs/B-epoxy also increased with an increase in the MWCNT content, which is a key factor affecting the EMI-SE.

바람이 불어오는 과정에서 지형 및 지물을 지나칠 경우 바람은 흐트러진다. 이 흐트러짐에 의해 풍속은 빨라질 수도 있고 느려질 수도 있다. 특히 건축물이 밀집되어 있는 도심지에서는 주로 속도가 느려지는 현상이 발생한다. 본 연구에서는 실물축척의 도심지를 재현하여 풍동실험을 통해 도심지에서의 차폐효과에 의한 풍속이 느려지는 현상을 정량적으로 평가하였다. 차폐효과에 큰 영향을 미칠 인자들을 도로폭과 주변건축물들의 평균적인 높이로 선정하였고 각각의 조건에 따른 차폐의 정도를 차폐계수로 정의하여 나타내었다. 연구의 결과로부터 도로방향으로 바람이 불 경우 왕복4차선 이하의 도로변에서의 차폐계수는 0.85 이하로 나타났고, 도로직 각방향으로 바람이 불 경우 왕복6차선 이하의 도로변에서의 차폐계수는 0.9 이하로 나타났다.