본 연구는 황기 에탄올 추출물과 황기 생물전환 추출물의 기능성 화장품 소재로서 가능성 여부를 규명하고자 하였다. 항산화 효과를 확인하기 위해 폴리페놀과 플라보노이드 함량을 측정하였고, 세포실험을 통해 피부 세포에 대한 독성과 피부 세포 노화에 대한 연구를 수행하였다. 항산화 실험 결과, 폴리페놀, 플라보노이드 효과에서는 폴리페놀과 플라보노이드의 함량이 농도 의존적으로 증가하였고, 생물전환 추출물에 비해 에탄올 추출물에서 높은 것으로 확인되었다. 황기 추출물과 생물전환된 황기추출물이 HDF 세포에서 농도 의존적으로 MMP1 발현 억제 효과가 증가되는 것을 확인하였다. 따라서 본 연구는 황기 추출물과 황기 생물전환 추출물의 기능성 화장품 소재로 사용 시 항산화와 피부 노화 예방 관점에서의 기능성 화장품 소재로 매우 유용하게 활용될 수 있을 것으로 사료된다.

Electrospinning, as one of the nano technologies for synthesizing nanofiber, is widely used in filtration, thermal insulation, protective clothing, sensors, conducting devices, and other fields due to its simple equipment, low cost and easy manipulation. The electrospun fibers have small diameter, high porosity, excellent pore interconnectivity, large specific surface area, easy surface modification, polymer chain functionalization and other advantages. Therefore, in this study, electrospinning technology was employed to synthesize multifunctional composite nanofiber membrane(polyacrylonitrile/fly ash/polyacrylonitrile, PAN/FA/AgNO3), which has the ability to remove volatile organic compounds(VOCs) and heavy metals; moreover, the membrane also has excellent antibacterial ability. This research result provides an important reference value for broadening the application of electrospinning technology in the field of air and water filtration in the future.

우리나라의 '해양오염방제 자재·약제의 성능시험기준 및 검정기준 중 ‘생물에 대한 영향시험’(생태독성시험)의 시험방법과 판정 기준의 개정과 관련한 방향을 제시하기 위해 현행 기준의 문제점을 파악하고 국가별 제도 비교를 통한 개선방안을 제시하였다. Skeletonema costatum을 이용한 성장저해시험의 경우, 배양액 색조를 비교하여 판단하는 기준 대신 측정된 성장률을 적절한 통계기법을 이용하여 비교 분석하는 과학적인 기준이 도입되어야 하며 시험기간의 경우, 지수성장기를 고려하여 4일 이내가 합당한 것으로 판단된다. 어류를 이용한 독성시험의 경우, 다양한 물질에 대한 독성시험 및 비교연구를 통해 방제 자재에 대해 일관되고 적절한 민감도를 나타낼 수 있는 보다 적절한 어체크기에 대한 재설정이 필요하고 이에 따른 합리적이고 객관적인 판정기준이 마련되어야 할 것으로 판단된다. 시험종의 경우, Artemia sp. 대신 해양 윤충류인 Rotifer, Brachionus plicatilis가 대안이 될 수 있으며 어류시험의 경우, 굴류(Oyster)와 같은 이매 패류의 분류군을 이용한 독성시험으로의 대체 역시 대안으로 고려될 수 있다. 마지막으로 해양오염방제 자재·약제의 형식승인 시험과 관련하여 생태독성시험 분야의 경우, 업무의 특수성과 결과의 신뢰성을 고려하여 별도의 공인시험기관 지정 또는 관련 유사 법률과 연계한 일원화된 창구가 필요하며 수용가능한 수준의 시험비용 산정과 시험항목 조정을 통한 합리적인 제도개선이 필요할 것으로 판단된다.

고온기 시설멜론 재배 시 저비용 고효율의 개발하기 위하여 차광 자재별 이용 효과를 구명하고자 수행하였다. 차광처리 에 따른 평균온도는 무차광이 36.6℃, 차광도포제는 34.5℃, 백색차광망은 34℃로 조사되었다. 도포제 살포 직후에 투광률이 무차광에 비해서 차광 도포제 처리구는 69%, 백색차광망 처리구는 75% 이었으나, 40일 및 80일 후 차광 도포제 처리구의 투광률이 각각 92% 및 98%로 높아져 처리된 차광도 포제가 서서히 제거되는 것을 알 수 있었으며, 백색차광망 처 리구는 시간의 경과에 따른 투광률의 변화가 거의 없었다. 생육에 있어 엽수는 처리 간에 차이가 없었고, 초장은 무차광에 비해 백색차광망과 차광도포제 처리구에서 높게 나타났다. 엽중, 생체중, 건물중의 경우 차광 처리구에 비해서 무차광에 서 정식 42일 후에는 더 무거운 것으로 나타났다. 총 상품수량 은 무차광에 비해서 백색차광망과 차광도포제가 각각 6% 및 5% 증수되었다. 따라서 고온기 간편하게 온도를 낮출수 있는 방법으로 차광도포제는 효과적이나 서서히 제거되기 때문에 재배 시기를 고려해서 사용하는 것이 바람직하다고 생각되었다.

PURPOSES : Recently, interest in maintaining aged concrete pavements has been increasing. An asphalt overlay is generally used for pavement maintenance, and a tack coat is used to secure interlayer adhesion. Particularly, aged concrete pavements are required for higher adhesion performance of tack coats for attaching interlayers to materials with different properties. Insufficient interlayer adhesion could cause pavement damage, such as slippage, rutting, shoving, corrugation, and pothole. In this study, we examined the performance of interface adhesion by applying a tack coat material developed for maintaining aged concrete pavement. METHODS : In this study, we examined the effect of adhesion performance at the pavement interface, using a tack coat material developed for the maintenance of aged concrete pavement. RESULTS : The developed tack coat not only accomplished the performance objectives but also improved the results by more than 12 to 43%, compared to commonly used materials. CONCLUSIONS : The use of developed tack coat is expected to improve the interlayer adhesion and reduce the delay of the maintenance process in aged concrete pavement.

The simultaneous use of KOH and nitrogen to manufacture carbon materials provides these materials with properties that the presence of only one of these additives would not give them, such as high porosity and reactivity. However, it is difficult to obtain nitrogen-doped carbon materials with both high porosity and high nitrogen content, as the KOH significantly reduces the nitrogen content. In this review the complex relationships between nitrogen content and nitrogen precursor amount, KOH amount and the activation temperature are discussed, with a focus on the different N-functional groups and the porosity of the fabricated carbons. Generally, increasing activation temperature and increasing KOH amount decrease the nitrogen content due to reactions with the N-containing substructures of carbon, resulting in the release of nitrogen as N2, HCN and other N gases. Increasing these parameters can also result in the reduction of pyridine-N while the amount of quaternary-N increases simultaneously. Besides this, an increase in the amount of nitrogen precursor leads to an increase in the porosity of N-doped materials. However, too high amounts of the nitrogen precursor generate an excess of nitrogen which blocks the pore system and consequently reduces the porosity of the doped carbons.

This study was conducted for the purpose of suggesting a standard that can be used under ambient temperature by improving the low mechanical and thermal properties of ABS. PC was used as a filler, and post-curing conditions of the ABS/PC blend injection material were investigated. It was found that the ABS/PC blend injection material having a PC content of 20 wt.% or more showed little change in tensile properties at a temperature of 50°C, and a decrease in tensile properties of less than 10% at 80°C.

Deuterium is a crucial clean energy source required for nuclear fusion and is a future resource needed in various industries and scientific fields. However, it is not easy to enrich deuterium because the proportion of deuterium in the hydrogen mixture is scarce, at approximately 0.016%. Furthermore, the physical and chemical properties of the hydrogen mixture and deuterium are very similar. Therefore, the efficient separation of deuterium from hydrogen mixtures is often a significant challenge when using modern separation technologies. Recently, to effectively separate deuterium, studies utilizing the ‘Kinetic Quantum Sieving Effect (KQS)’ of porous materials are increasing. Therefore, in this review, two different strategies have been discussed for improving KQS efficiency for hydrogen isotope separation performance using nanoporous materials. One is the gating effect, which precisely controls the aperture locally by adjusting the temperature and pressure. The second is the breathing phenomenon, utilizing the volume change of the structure from closed system to open system. It has been reported that efficient hydrogen isotope separation is possible using these two methods, and each of these effects is described in detail in this review. In addition, a specific-isotope responsive system (e.g., 2nd breathing effect in MIL-53) has recently been discovered and is described here as well.

본 연구에서는 DNA barcode 시험법을 이용하여 시중 유통 중인 도미와 옥돔 수산가공식품의 위변조현황을 분석하였다. 참돔 12건, 돌돔 4건, 황돔 7건, 감성돔 2건, 나일틸라피아 7건, 옥돔 6건, 옥두어 8건 총 46건의 시료에 대해 실험을 진행하였다. 생물 종 판별에 주로 이용되는 mitochondrial DNA의 COX I (cytochrome C oxidase subunit I) 유전자 영역을 분석하여 원재료의 종을 판정하였다. NCBI에서 제공하는 BLAST Search 프로그램을 이용하여 분석된 염기서열과 NCBI에 등록된 각각 어류의 유전자 염기서열을 비교하였다. 분석 결과 염기서열 상동 성(identity)이 97% 이상인 종을 원재료 종으로 판별하였다. DNA barcode 시험법을 이용해 시중 유통되는 참돔, 돌돔, 황돔, 감성돔, 나일틸라피아, 옥돔, 옥두 수산가공품 46건에 대해 조사한 결과 위변조 사례는 나타나지 않았다. 그러나 시장에서 통용되는 일반명칭과 식품공전에 기술된 표준명칭이 상이하여 소비자의 혼란을 야기할 수 있어 수산물 가공식품 표기에 일반명칭과 더불어 표준명칭 또는 학명을 같이 기술하여야 할 것으로 판단되었다.

본 연구에서는 처리용기의 재질에 따른 광펄스의 살균 효과에 대해서 알아보았다. 처리용기의 재질에 따른 UV-C 의 광량은 대조구는 3.595W/m2이었으며, 두께 1 mm에서 석영은 3.358W/m2, 아크릴은 0.878W/m2, 그리고 유리는 0.060W/m2였으며, 빛의 투과율은 석영은 93.4%, 아크릴은 24.4%, 유리는 1.7%로 나타났다. 처리 용기 재질에 따른 살균 효과는 석영은 처리용기의 두께와 상관없이 대조구와 동일한 살균 효과를 보였으며, 아크릴은 1 mm 두께에서 60초 처리 후 1.1 log 사멸하였으며, 180초 처리 후에는 5.0 log의 사멸효과를 보였으며, 두께가 증가함에 따라 살균 효과가 현저히 감소하였다. 유리는 두께와 관계없이 살균 효과가 거의 없었다. 사멸패턴은 유리를 제외하고는 모두 bi-phasic의 형태를 보였으며, 사멸속도상수와 D 값은 대조 구는 k1값은 0.287 s−1이었으며, k2값은 0.072 s−1이었고, D1 은 8.02 s였으며, D2는 31.87 s였다. 1 mm의 두께에서 석영 은 k1은 0.284 s−1, k2는 0.069 s−1, 아크릴은 k1은 0.018 s−1, k2는 0.042 s−1이었고, 유리는 k는 0.004 s−1이었다. 두께 1 mm에서 D값은 석영은 D1=8.11 s, D2=33.87, 아크릴은 D1 =127.94 s, D2=54.83 s, 유리는 D=575.75 s로 나타났다.

PURPOSES : This study aims to develop drainage minor-structure materials using asphalt mixtures, and to apply construction methods. METHODS : The AP-5, 120-150A, and 150-200A binders were adopted to select the optimal asphalt binder for the domestic application of asphalt concrete in curb construction. The mixture design of asphalt mixtures has applied the standard for evaluating asphalt curb mixtures in Korea. Test construction utilized asphalt curb equipment to evaluate asphalt mixtures, according to the type of asphalt binder. RESULTS : The results of the asphalt mixture design indicated that the optimum asphalt content was determined at 2–3% air void for each type of asphalt binder, and the quality of the asphalt mixture applied with asphalt curb binder was excellent. In addition, the quality difference was significant, depending on the temperature of the asphalt mixture at each phase of the asphalt curb construction. CONCLUSIONS : Asphalt curb construction using asphalt materials has a large impact on the quality, depending on the temperature of the asphalt mixture, therefore management at the appropriate temperature is important when applying it to the site. Further research is also required on the production, transportation, and dedicated equipment of asphalt mixtures.

In this study, binderless-WC, WC-6 wt%Co, WC-6wt% 1 and 2.5 B4C materials are fabricated by spark plasma sintering process (SPS process). Each fabricated WC material is almost completely dense, with a relative density up to 99.5 % after the simultaneous application of pressure of 60 MPa. The WC added Co and Co-B4C materials resulted in crystalline growth. The WC with HCP crystal structure has respective interfacial energy (basal facet direction: 1.07 ~ 1.34 J·m−2, prismatic direction: 1.43 ~ 3.02 J·m−2) that depends on the grain growth direction. It is confirmed that the continuous grain growth, biased by the basal facet, which has relatively low energy, is promoted at the WC/Co interface. As abnormal grain growth takes place, the grain size increases more than twice from 0.37 to 0.8 um. It is found through analysis that the hardness property also greatly decreases from about 2661.4 to 1721.4 kg/mm2, along with the grain growth.

Expensive PCBN or ceramic cutting tools are used for processing of difficult-to-cut materials such as Ti and Ni alloy materials. These tools have the problem of breaking easily due to their high hardness but low fracture toughness. To solve these problems, cutting tools that form various coating layers are used in low-cost WC-Co hard material tools, and research on various tool materials is being conducted. In this study, binderless-WC, WC-6 wt%Co, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co-2.5 wt% Mo2C hard materials are densified using horizontal ball milled WC-Co, WC-Co-Mo2C powders, and spark plasma sintering process (SPS process). Each SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co- 2.5 wt% Mo2C hard materials are almost completely dense, with relative density of up to 99.5 % after the simultaneous application of pressure of 60 MPa and almost no significant change in grain size. The average grain sizes of WC for Binderless- WC, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co-2.5 wt% Mo2C hard materials are about 0.37, 0.6, 0.54, and 0.43 μm, respectively. Mechanical properties, microstructure, and phase analysis of SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo2C, and WC-6 wt%Co-2.5 wt% Mo2C hard materials are investigated.

Because of the International Maritime Organization(IMO)'s regulation to regulate emissions of ships, a change is taking place to replace ship fuels from Heavy Fule Oil(HFO) to Liquefied Natural Gas(LNG). In the case of LNG, it is a material obtained by liquefying Natural Gas(NG), and it is -163 degrees below zero, and the volume is reduced to 1/600 level. The material of the tank that can store LNG must be a material that can safely store LNG in a cryogenic environment, and the materials of the tank that can store LNG are limited in the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code). Among the materials listed in the IGC Code, 9% nickel steel is used as a material for LNG fuel propulsion tanks that are recently ordered because of relatively high mechanical properties under cryogenic environments. In this study, the mechanical properties of butt welds were measured following the weld reliability evaluation of Flux Cored Arc Welding(FCAW) butt welds made of 9% nickel steel by PARTI. The measured mechanical properties are tensile strength, bending strength, hardness, and cryogenic impact test required by the classification for Welding Procedure Specification(WPS) approval.

When performing finite element analysis using materials with porosity the porosity shows different mechanical properties from the existing mechanical properties of the existing base materials. In this study the equivalent properties were calculated and verified by applying the representative volume element (RVE) method and assuming that the material with porosity is a 2D orthotropic material. In case of finite element analysis using porous material or composite material, it is inefficient to perform the analysis through material modeling. Based on the element volume and element stress values ​​derived using the finite element analysis program, the representative stress values ​​and elastic modulus matrix were calculated using Python. In addition, equivalent properties were derived using the calculated elastic modulus matrix. The pores were simulated by etching a thin plate specimen made of STS304 material in a certain pattern, and the elastic modulus and Poisson's ratio were measured through a UTM and compared with simulation results. It was confirmed that an error of 7.028% for elastic modulus and 10% for Poisson's ratio occurred, and through this, the validity of this simulation was verified.

Because of the International Maritime Organization(IMO)'s regulation to regulate emissions of ships, a change is taking place to replace ship fuels from Heavy Fule Oil(HFO) to Liquefied Natural Gas(LNG). In the case of LNG, it is a material obtained by liquefying Natural Gas(NG), and it is -163 degrees below zero, and the volume is reduced to 1/600 level. The material of the tank that can store LNG must be a material that can safely store LNG in a cryogenic environment, and the materials of the tank that can store LNG are limited in the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code). Among the materials listed in the IGC Code, 9% nickel steel is used as a material for LNG fuel propulsion tanks that are recently ordered because of relatively high mechanical properties under cryogenic environments. In this study, butt welding was performed on a 9% nickel steel material using Flux Cored Arc Welding(FCAW), the most widely used welding method in shipyards. In PARTI, after securing the welding conditions, cross-sectional observation results analysis, liquid penetrating test, and radiographic test were performed to verify the reliability of the weld.

The demand for materials with porosity is steadily increasing and the need for porous materials is increasing in fields such as chemical engineering and energy storage. In order to minimize trial and error, verifying design validity through finite element method at the design stage has the advantage to verify design validity with low cost. However there are limitations in finite element analysis using porous materials. In this study calculating the equivalent mechanical properties reflecting the porosity was carried out, and the first step was the isotropic elasticity in plane stress condition. The equivalent elastic modulus and the equivalent Poisson's ratio were derived through simulation. Assuming that the voids exist in a two-dimensional symmetrical shape and a constant distribution, the unit cell was defined and the equivalent mechanical properties were calculated. The specimen with same condition were measured through a universal test machine (UTM), the elastic modulus and Poisson's ratio were measured. The similarity between the value obtained through the simulation and the value measured through the experiment was under 5%, so the validity of this simulation was verified. With this result, FEM with porous materials will be used for design.

There is increasing demand for the development of a new material with high strength, high stiffness, and good electrical conductivity that can be used for high-voltage direct current cables. In this study, we develop aluminumbased composites containing C60 fullerenes, carbon nanotubes, or graphene using a powder metallurgical route and evaluate their strength, stiffness, coefficient of thermal expansion, and electrical conductivity. By optimizing the process conditions, a material with a tensile strength of 800 MPa, an elastic modulus of 90 GPa, and an electrical conductivity of 40% IACS is obtained, which may replace iron-core cables. Furthermore, by designing the type and volume fraction of the reinforcement, a material with a tensile strength of 380 MPa, elastic modulus of 80 GPa, and electrical conductivity of 54% IACS is obtained, which may compete with AA 6201 aluminum alloys for use in all-aluminum conductor cables.

Metal three-dimensional (3D) printing is an important emerging processing method in powder metallurgy. There are many successful applications of additive manufacturing. However, processing parameters such as laser power and scan speed must be manually optimized despite the development of artificial intelligence. Automatic calibration using information in an additive manufacturing database is desirable. In this study, 15 commercial pure titanium samples are processed under different conditions, and the 3D pore structures are characterized by X-ray tomography. These samples are easily classified into three categories, unmelted, well melted, or overmelted, depending on the laser energy density. Using more than 10,000 projected images for each category, convolutional neural networks are applied, and almost perfect classification of these samples is obtained. This result demonstrates that machine learning methods based on X-ray tomography can be helpful to automatically identify more suitable processing parameters.