Exposure to ultraviolet (UV) light is often associated with skin damage, sometimes very serious, and in recent times has received particular attention as a health risk. As a result, the proper use of sunscreen has long been recommended to protect against skin damage. The continued increase in the use of sunscreen may be linked to increased information about the risk of melanoma and non-melanoma skin cancer caused by prolonged exposure to ultraviolet rays. Natural and harmless materials that block and prevent UV light have emerged as essential household items in the field of skin beauty. New materials need to be considered and evaluated in relation to ultraviolet rays and their harmful effects. This study aims to explain the effect of UV exposure on human skin, the classification of sunscreens, the application of zeolite, nano clay, and LDH in sunscreen formulations, as well as the regulation of this service in various countries around the world.

본 연구는 코팅 방법을 활용한 단결정 양극 소재 연구로서 Ni-rich계 다결정 양극 소재로 부터 단결정 양극 소재를 합 성하여 사이클 구동 시 양극 소재의 안정성을 향상시키고자 한다. 양극 소재에 LixCoO2와 LixSnO3 를 각각 코팅하여 이차입자 내부 혹은 외부에 코팅층이 형성된 양극 소재를 합성한 후 이를 소결하여 단결정 형성에 대한 영향을 비교 하였다. 입자 외부에 LixSnO3가 코팅되어 열처리 된 Ni0.8Co0.1Mn0.1O2(NCM811)의 경우 코팅 처리 없이 열처리된 양극 소재 보다 개선된 수명특성을 보였으나, 단결정화가 이뤄지지 않았다. 입자 내부에 LixCoO2 코팅층이 형성된 NCM811 을 열처리 한 결과 이차입자 내부에 형성된 Co 코팅층이 결정화되어 50회 사이클 후 기준 단결정 양극 소재의 방전용 량인 117.34 mAh·g-1 대비 129.11 mAh·g-1의 높은 방전용량을 나타내었고, 형상제어를 통해 이성적인 단결정화가 이뤄 졌다. 본 연구는 다결정체인 Ni-rich 양극소재의 단결정화에 대한 유요한 통찰력을 제공할 것으로 예상한다.

Following the social requirement to strengthen field supervision of the asbestos containing materials (ACM) abatement process with regard to asbestos school buildings, this study was conducted to understand the status and characteristics of airborne asbestos that may potentially occur after the ACM abatement process is completed. In the area where a series of asbestos abatement processes were finally completed, comprehensive area air sampling was performed. For sample analysis, Transmission Electron Microscopy (TEM) was used according to The Asbestos Hazard Emergency Response Act (AHERA) method and Phase Contrast Microscopy (PCM) analysis was also performed. Airborne asbestos was detected in 29.5% of the total samples, and the average concentration was 0.0039 ± 0.0123 s/cc (12.3 ± 38.9 s/mm2). 4.5% of the total samples exceeded the AHERA standard (70.0 s/mm2) and the average concentration was 0.0528 ± 0.0256 s/cc (167.2 ± 82.0 s/mm2). Airborne asbestos was no longer detected at the point when AHERA is exceeded after re-cleaning. Most of the detected asbestos was chrysotile (94.4%) and the structure types of asbestos were Matrix (41.4%), Fiber (39.9%), Bundle (10.8%), and Cluster (7.8%). Among the asbestos structures detected through transmission electron microscope analysis, the asbestos structures satisfying PCM-equivalent structures were found to be 6% of the detected asbestos, indicating that there is a limitation of the PCM analysis to check the airborne asbestos in that area. As a result of reviewing the status of airborne asbestos that may potentially occur and the type and dimensions of asbestos structure detected in the area, since the airborne asbestos exposure caused by poor field supervision for the ACM abatement process could not be ruled out, thorough management is necessary. In addition, the result of this study could be used as scientific evidence for establishing and strengthening policies related to ACM abatement, including cases of school buildings.

We attempted to provide an overview of the laws and current state of the 3D printing industry in South Korea and around the world, using the annual industry surveys and the Wohler report. Additionally, we reviewed articles relating to the potential exposure to hazards associated with 3D printing using metal materials. In South Korea, there were 406 3D printing-related businesses, employing 2,365 workers, and the market size was estimated at 455.9 billion won in 2021. Globally, the average growth rate of the 3D printing industry market over the past 10 years was 27.4%, and the market size was estimated at $11.8 billion in 2019. The United States had the highest cumulative installation ratio of industrial 3D printers, followed by China, Japan, Germany, and South Korea. A total of 6,168 patents related to 3D printing were registered in the US between 2010 and 2019. Harmful factors during metal 3D printing was mainly evaluated in the powder bed fusion and direct energy deposition printing types, and there is a case of material extrusion type with metal additive filaments. The number, mass, size distribution, and chemical composition of particles were mainly evaluated. Particle concentration increases during the opening of the chamber or post-processing. However, operating the 3D printer in a ventilated chamber can reduce particle concentration to the background level. In order to have a safe and healthy environment for 3D printing, it is necessary to accumulate and apply knowledge through various studies.

This research studied the electrical characteristics, IR transmission characteristics, stealth functions, and thermal characteristics of infrared thermal-imaging cameras of copper-sputtered samples. Nylon samples were prepared for each density as a base material for copper-sputtering treatment. Copper-sputtered NFi, NM1, NM2, NM3, NM4, and NM5, showed electrical resistance of 0.8, 445.7, 80.7, 29.7, 0.3, and 2.2 Ω, respectively, all of which are very low values; for the mesh sample, the lower the density, the lower the electrical resistance. Measuring the IR transmittance showed that the infrared transmittance of the copper-sputtered samples was significantly reduced compared to the untreated sample. Compared to the untreated samples, the transmittance went from 92.0–64.1%. When copper sputtered surface was directed to the IR irradiator, the IR transmittance went from 73.5 to 43.8%. As the density of the sample increased, the transmittance tended to decreased. After the infrared thermal imaging, the absolute values of △R, △G, and △B of the copper phase increased from 2 to 167, 98 to 192, and 7 to 118, respectively, and the closer the density of the sample (NM5→NFi), the larger the absolute value. This proves that the dense copper phase-up sample has a stealth effect on the infrared thermal imaging camera. It is believed that the copper-sputtered nylon samples produced in this study have applications in multifunctional uniforms, bio-signal detection sensors, stage costumes, etc.

Devices with negative differential transconductance (NDT) and negative differential resistance (NDR) have shown a strong potential for digital electronics with high information density due to their N-shaped current–voltage (I–V) characteristics leading to multiple threshold voltages ( Vths). The 2D materials, such as graphene, hBN, MoS2, WS2, etc., offer an attractive platform to achieve NDT and NDR because of the absence of dangling bonds on the surface, leading to a high-quality interface between the layers. The 2D materials' unique property of the weak van der Waals (vdW) interactions without dangling bonds on the heterostructure devices shows the way for the applications more than-Moore devices. This review holds a well-timed overview of 2D materials-based devices to develop future multi-valued logic (MVL) circuits exhibiting high information density. Notably, the recent advances in emerging 2D materials are reviewed to support the directions for future research on MVL applications.

A fixed-point iteration is proposed to integrate the stress and state variables in the incremental analysis of plastic deformation. The Conventional Newton–Raphson method requires a second-order derivative of the yield function to generate a complicated code, and the convergence cannot be guaranteed beforehand. The proposed fixed-point iteration does not require a second-order derivative of the yield function, and convergence is ensured for a given strain increment. The fixed-point iteration is easier to implement, and the computational time is shortened compared with the Newton–Raphson method. The plane-stress condition is considered for the biaxial loading conditions to confirm the convergence of the fixed-point iteration. 3-dimensional tensile specimen is considered to compare the computational times in the ABAQUS/explicit finite element analysis.

정부는 행정규제기본법 개정(‘19.07.17)을 통하여 경제활력 제고를 위하여 규제를 최소화하고 포괄적 네거티브 규제원칙을 적용하였다. 사전규제에서 우선허용-사후규제로의 정책환경이 변화하였다. 하지만 해양오염방제 자재․약제는 법적의무인증제도가 적 용되어 제품을 판매할 때마다 검정을 실시하여 제조업체의 자율성을 억제하여 왔다. 또한 방제자재․약제 생산업체는 대부분 영세하 여 구입자가 주문 의뢰 시마다 제품을 소량 생산하는 방식을 취하고 있다. 이에 해양오염방제 자재․약제 형식승인, 성능시험, 검정 제도도 시대의 흐름에 맞춰 시장 및 업계의 자율성을 보장하고 효율성 향상을 위해 규제완화의 필요성이 제기되었다. 본 연구에서는 현 제도의 문제점을 파악하고 국내․외 제도를 비교․분석을 통한 개선방안을 제안하였다.

지구의 기후 변화를 유도하고 제어하는 가장 중요한 역할을 하는 것은 해양의 해류이다. 황해는 수심이 동해 에 비해 매우 얕고, 다양한 바람과 조류, 강물의 유입, 동중국해에서의 해수 유입 등 외력의 영향으로 해수의 순환과 해류가 상당히 복잡하다. 황해난류는 겨울철 황해의 대표적인 해류로서 겨울철 황해와 동중국해 바람 변동성과 밀접한 관련이 있으며, 황해의 수온과 염분 분포에 큰 영향을 주어서 중등학교 교과서에서 중요하게 다루어질 필요성이 있다. 2015 개정 교육과정 기반 중등학교 과학 및 지구과학 교과서의 황해난류와 관련된 내용을 분석하였다. 또한 해류의 시 간 변동성에 대한 교사들의 인식을 조사하기 위해 중등학교 과학 교사들을 대상으로 설문조사를 실시하였다. 대부분의 교사들은 황해난류가 우리나라 서해안으로 연중 북상하고 있으며 일반적인 난류와 같이 여름철에 강하다는 잘못된 지 식을 가지고 있는 것으로 나타났다. 황해난류는 해류의 세기가 강한 계절변동성을 가지는 북한한류와 달리 해류 자체가 연중 항시 존재하지 않으며 겨울철에만 발생하는 해류이다. 이러한 교사들의 교과내용 지식에 대한 오류는 북한한류가 겨울철에 강하다는 오개념을 가지게 된 연유와 유사한 배경을 가지고 있었다. 따라서 본 연구에서는 황해난류에 대한 교과서 내용의 오류를 분석하여 제시하였다. 또한 학생들과 교사들의 데이터 리터러시 함양을 위하여 탐구활동에서 활 용할 수 있는 황해난류에 대한 수업 자료를 개발하였다. 황해 해수면 온도를 가시화할 수 있는 GUI 프로그램을 소개하 였고, WOA (World Ocean Atlas) 2018 해양 실측 수온 및 염분자료와 국립해양조사원에서 생성한 해양 수치모델 재분 석자료를 활용하여 수온과 염분의 공간 분포를 도시하는 자료를 개발하여 제시하였다. 이러한 해양 자료를 활용한 데이 터 시각화과정은 교사들의 오개념을 개선하고, 나아가 학생들과 교사들의 해양 리터러시뿐만 아니라 데이터 리터러시도 제고하는 계기가 될 것으로 기대된다.

The construction method of scaffolding structures is different from Mortise and Tenon and bucket arch structure of traditional large woodwork. It forms an independent construction system-fixing nodes with knots, a large number of diagonal braces are used to fix shelves and the structures mostly contain X-shape and triangular shape details. Simple ones include stalls, sheds, rain sheds, altars, lamp racks etc. But the scaffolding with larger scale and more complicated structure are modeled on archways, theatres and other buildings which are used in commercial and festival activities. At present, Macao, Hong Kong, Guangdong, Sichuan, Shanxi and other places in China have retained the custom of using scaffolding structures in important festival activities, but their uses, techniques and building types are slightly different from place to place. Due to building and demolishing at any time, the construction and service cycle is short. As a result, there are almost no physical objects left. We can only deduce the use and technical characteristics of ancient scaffolding skills through the colorful building styles that have been preserved with folk activities in various parts of China, the craftsmanship handed down from generation to generation by the scaffolding guild and artisans, and the description of cultural and historical materials and the mutual corroboration of visual materials.

As the time and cost of body repair can be greatly incurred due to differences in individual technologies, body repair technology should be discussed based on data on general working standards and costs, and as new material technology is applied to the body, continuous learning and experiment on vehicle body repair technology is essential. Since the left and right apron and side members with SPR bonding technology are made of different materials, aluminum and high-strength steel, the restoration of the left and right apron side members should be considered technically, as well as safety and environmental pollution. In this study, we experiment with heterogeneous apron and side members applied with SPR bonding and analyze the results.

The external weather conditions including temperature and wind speed in the Saemangeum reclaimed land is different from that of the inland, affecting the internal environment of the greenhouse. Therefore, it is important to select an appropriate covering material considering the insulation effect according to the type and characteristics of the covering material considering the weather condition in the Saemangeum reclaimed land. A hexahedral insulation chamber was designed to evaluate the insulation efficiency of each glass-clad material in the outside weather condition in reclaimed land. In order to evaluate the insulation effect of each covering material, a radiator was installed and real-time power consumption was monitored. 16-mm PC (polycarbonate), 16-mm PMMA (polymethyl methacrylate), 4-mm greenhouse glass, and 16-mm double-layered glass were used as the covering materials of the chamber. In order to understand the effect of the external wind directions, the windward and downwind insulation properties were evaluated. As a result of comparing the thermal insulation effect of each greenhouse cover material to single-layer glass, the thermal insulation effect of double-layer glass was 16.9% higher, while PMMA and PC were 62.5% and 131.2% higher respectively. On average the wind speed on the windward side was 53.1% higher than that on the lee-wind side, and the temperature difference between the inside and outside of the chamber at the wind ward side was found to be 52.0% larger than that on the lee ward side. During the experiment period, the overall heating operation time for PC was 39.2% lower compared to other insulation materials. Showing highest energy efficiency, and compared to PC, single-layer glass power consumption was 37.4% higher.

Nonporous materials have nano-sized pores. High specific surface area and size and shape selectivity (size and shape Selectivity) are the most important features of these materials that have led to their widespread use in various industries, such as catalysts, water treatment and separation of pollutants. The development of properties and applications of these materials depends on the fabrication of nanoporous materials with optimal and controlled structures. In this paper, porous nanostructures and supermolecular chemistry are introduced in detail. Then, a number of common nanoporous materials, such as activated carbon, metal–organic frameworks and zeolites, then various types of mineral and organic nanoporous materials as well as methods of synthesis, characterization and applications of these materials will be studied in detail.