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        검색결과 22

        1.
        2023.10 구독 인증기관·개인회원 무료
        From an evolutionary perspective, it is speculated that termites have evolved to construct tunnels in a manner that optimizes search and transport efficiency. While numerous studies have focused on search efficiency, there has been limited research on transport efficiency due to the challenges associated with direct field observations. To address this challenge, we developed an individual-based model to simulate the transport process. Using the model, we examine the effects of several key variables on transport efficiency, Based on our results, we discuss potential strategies that termites might employ to optimize transport efficiency. In addition, we briefly discuss ways to improve the realism of the model.
        2.
        2023.05 구독 인증기관·개인회원 무료
        A deep geological repository for disposal of high-level radioactive waste (HLW) consists of the canister, buffer material, and natural rock. If radionuclides leak from a disposal container, it can pass through buffer materials and rock, and move into the biosphere. Transport and migration of radionuclides in the rock differently were affected by the fracture type, filling minerals in the fracture, and the chemical and hydraulic properties of the groundwater. In this study, aperture distribution in fractured granite block was investigated by hydraulic test and CFD analysis. The fractured rock block (1 m × 0.6 m × 0.6 m), which is simulated as natural barrier, was prepared from Iksan, Jeollabuk-do. 9 test holes were drilled and packer system was installed to perform hydraulic test at the surface of fracture. 3D model simulated for aperture distribution of rock block was made using results of hydraulic test. And then, CFD analysis was performed to evaluate the co-relation between experiment results and analysis results using FLUENT code.
        5.
        2018.11 구독 인증기관·개인회원 무료
        A highly performing and durable forward osmosis (FO) membrane was prepared using a polydopamine-modified polyolefin (DPO) support via an aromatic solvent (toluene)-based interfacial polymerization (IP). The hydrophobic polyolefin support was uniformly hydrophilized by polydopamine coating, which provided long term operation stability. In addition, a highly permselective selective layer was prepared on the hydrophilic DPO support by the toluene-based IP, which promoted amine diffusion and the subsequent IP reaction. As a result, the prepared DPO-supported TFC membrane exhibited significantly high FO performance, which was ~4.9 times higher FO water flux and ~62% lower specific salt flux than those of a commercial FO (HTI-CTA) membrane in FO mode. Furthermore, its excellent mechanical and chemical stability enabled stable operation.
        6.
        2018.05 구독 인증기관·개인회원 무료
        Well-defined methacrylate based amphiphilic block copolymers (BCs) used as additives to fabricate poly(vinylidene fluoride) (PVDF) UF membranes, where the amphiphilic BC additives hydrophilically altered PVDF with PPEGMA block segment by strong interaction with the other PMMA block segment, which reduced water resistance to the PVDF polymer solution during phase separation. FT-IR and XPS studies showed carbonyl groups of BCs in the PVDF membranes. Obtained membranes showed porous surface layer and finger-like pore structures on the sublayers, of which sizes were increased with the increase of BC contents. Obtained membranes showed MWCO with 100K PEO and the best water flux was achieved in the PVDF membrane with BC/LiCl additive and improved the anti-fouling property for BSA protein.
        7.
        2018.05 구독 인증기관·개인회원 무료
        Growing demands for reducing energy consumption have raised interest to design advanced materials for thin film composite (TFC) desalination membranes with high permselectivity and low fouling. Here, we synthesized a star-shaped polymer as a new building block material, which can be assembled into selective layer of the TFC membrane via a facile interfacial polymerization (IP). Star polymer with compact globular structure and high density amine functional groups enabled to fabricate higher permselectivity and lower fouling propensity membrane compared to commercial membranes. In addition, star polymer assembled TFC membrane can function as either nanofiltration or reverse osmosis membrane by simply adjusting IP process conditions, which cannot feasible in conventional materials, demonstrating remarkable versatility of our star polymer.
        8.
        2017.11 구독 인증기관·개인회원 무료
        A series of amphiphilic block copolymers consisting of hydrophobic poly(methyl methacrylate) (PMMA) and poly(polyethylene glycol methyl ether methacrylate) (PPEGEMA) were synthesized by Cu based ATRP and utilized as an additive to prepare asymmetric ultrafiltration (UF) membranes by non-solvent induced phase separation (NIPS) with PVDF. Obtained PVDF based UF membranes gave in-situ hydrophilic surfaces on the hydrophobic PVDF matrix because of strong compatibility PMMA block segment to PVDF and the hydrophilicty of PPEGMA block segment to the non-solvent (water), which showed improved water flux in comparison to neat PVDF UF membrane.
        9.
        2017.11 구독 인증기관·개인회원 무료
        The highly performing polyamide (PA) thin film composite (TFC) reverse osmosis (RO) membrane was prepared using the commercialized porous polyolefin (PO) membrane as a support. The PO-supported TFC (PO-TFC) membrane was fabricated via a conventional interfacial polymerization process. The highly permselective PA layer was formed by optimizing membrane fabrication parameters such as monomer/additive composition and post-treatment. The uniform pore structure and high surface porosity of the PO support are beneficial for improving the membrane permselectivity. As a result, the prepared PO-TFC membrane showed ~30% higher water flux and ~0.4% higher NaCl rejection compared to a commercial RO membrane. In addition, the PO-TFC membrane exhibited excellent mechanical properties and organic solvent resistance.
        10.
        2017.05 구독 인증기관·개인회원 무료
        A porous polyolefin (e.g. polypropylene and polyethylene) membrane has been commercialized as a lithium ion battery separator. The highly performing thin film composite (TFC) forward osmosis (FO) membrane was fabricated using the porous polyolefin membrane as a support via typical interfacial polymerization process. A very thin thickness (~8 μm) and highly interconnected pore structure of the polyolefin support can greatly reduce the internal concentration polarization, leading to high water flux, as evidenced by its low structural parameter (~168 μm). The prepared polyolefin-supported TFC membrane showed ~3.7 times higher water flux and ~33% lower specific salt flux compared to HTI-CTA commercial FO membrane with 1.0 M NaCl draw solution and DI water feed solution in FO mode. In addition, its excellent mechanical strength enables stable membrane operation.
        12.
        2015.05 구독 인증기관·개인회원 무료
        The silver nanoparticles (AgNPs) incorporated reverse osmosis (RO) membranes with an excellent antibacterial property has been reported. However, the incorporated AgNPs could increase the hydraulic resistance of membrane, indicating the decline of water flux. Here, hybrid silver nanoparticles (Ag@SiO2, 400 nm) were strongly immobilized using Ag-S chemical bonding on the polyamide surface of RO membrane for both protecting the decline membrane performance and having a strong antimicrobial property. The membrane performance was unchanged after the immobilization of silver nanoparticles, when compared to that of unmodified membrane. In addition, the silver-polyamide composite membrane significant reduced the number of live bacteria attached on the membrane surface by 92.7 ± 1.8, 99.5 ± 0.3, and 73.3 ± 5.5% for E. coli, P. aeruginosa, and S. aureus, respectively. The strong antimicrobial property is ascribed to the combination effect by the directly attachment to bacteria surface and the penetration of released silver ions inside the cell membrane of bacteria.
        13.
        2014.04 구독 인증기관 무료, 개인회원 유료
        Artificial insemination technique has been contributed immensely for production of livestock worldwide as a critical assisted reproductive technique to preserve and propagate excellent genes in domestic animal industry. In the past decade, methods for semen preservation have been improved mostly in liquid preservation method for boar semen and freezing method for bull semen. Among many factors affecting semen quality during preservation, reactive oxy-gen species, produced by aerobic respiration in sperm for survival and motility, are unfavorable to sperm physiology. In mammalian cell as well as in the sperm, antioxidant system plays a role in degradation of reactive oxygen species. Magnetized water forms smaller stabilizing water clusters, resulting in high absorption and permeability of the cell for water, implicating its application for semen preservation. Therefore, this review focuses on preservation methods of boar and bull semen with respect to improvement of extender and reduction of reactive oxygen species by using magnetized water and supplementation of antioxidants.
        4,000원
        14.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적: 이 연구는 안경사의 1일 근무시간이나 정기휴무 등의 복지관련 실태를 조사하여 복지를 개선하기 위한 기초자료를 제공하고자 한다. 방법: 부산시안경사회에서 2012년 4월 보수교육시 533명(남자 379명, 여자 154명)의 안경사를 대상으로 안경사 복지에 대한 설문조사를 실시하였다. 설문지는 일반사항 10문항과 복지증진관련사항 20문항의 총 30문항으로 구성되었다. 결과: 안경사 실무자들이 휴직이나 이직을 고려하는 가장 중요한 이유는 장시간의 근무시간(38%)과 정기 휴무제 미흡(17%) 때문이었다. 업무와 관련된 스트레스는 안경사의 절반 이상(56%)에서 스트레스 정도가 높거나 매우 높은 것으로 나타났다. 업무에서 가장 가치를 두고 있는 것이 정기 휴무제 실시(36%)와 1일 근무시간 단축(34%)이지만, 실제 정기휴무를 실시하는 안경원은 33%에 불과하였다. 그리고 안경사의 72%가 현재 1일 11시간 이상을 근무하고 있고, 대부분의 안경사인 95%에서 희망하는 1일 근무시간은 8~10시간이었다. 안경사의 91%가 정기 휴무제 실시를 찬성하고 있고, 또한 휴무제 시행에도 적극 동참할 의사를 밝혔다. 결론: 장시간의 1일 근무시간과 정기 휴무제 미흡으로 인한 열악한 근로조건은 고용상태를 불안정하게 만들고, 업무와 관련된 스트레스를 가중시키고 있다. 이를 개선하기 위해 모두가 동참하여 안경사의 복지를 향상시켜나가야 할 것이다.
        4,800원
        16.
        2009.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, the effect of carbon nanofibers (CNFs) addition on physicochemical characteristics of CNFs-reinforced epoxy matrix nanocomposites was studied. Poly(amide imide) solutions in dimethylformamide were electrospun into webs consisting of 250±50 nm fibers which were used to produce CNFs through stabilization and carbonization processes. As a result, the CNFs with average diameter of 200±20 nm were obtained after carbonization process. The nanocomposites with CNFs showed an improvement of thermal stability parameters and fracture toughness factors, compared to those of the specimen without CNFs, which could be probably attributed to the higher specific surface area and larger aspect ratio of CNFs, resulting in improving the mechanical interlocking in the nanocomposites. Also, the applied external loading can effectively transfer to CNFs because strong interactions are resulted between the epoxy matrix and the CNFs.
        4,000원
        19.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon fibers are a new breed of high-strength materials. The existence of carbon fiber came into being in 1879 when Edison took out a patent for the manufacture of carbon filaments suitable for use in electric lamps. However, it was in the early 1960s when successful commercial production was started, as the requirements of the aerospace industry for better and lightweight materials became of paramount importance. In recent decades, carbon fibers have found wide applications in commercial and civilian aircraft, along with recreational, industrial, and transportation markets as the price of carbon fiber has come down and technologies have matured. The market for carbon fiber has experienced a good growth in recent years. The growth rate for the last 23years was about 12%. The article reviewed 9,641 Korea, U.S., Japan, Europe patents issued in the carbon fibers in order to offer additional insight for researchers and companies seeking to navigate carbon fiber patent landscape. This article will provide you with all the valuable information and tools you will need to investigate your study successfully within the carbon fiber field. This article also will save you hundreds of hours of your own personal research time and will significantly benefit you in expanding your business in the carbon fiber market.
        4,000원
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