• Title/Summary/Keyword: Metal Type

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A study on the fatigue bending strength of quasi-isotropic CFRP laminates subjected to impact damage (축격손상을 받은 의사등방성 탄소섬유강화 복합재의 굽힘피로강도)

  • Park, Soo-Chul;Park, Seol-Hyeon;Jung, Jong-An;Cha, Cheon-Seok;Yang, Yong-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.688-695
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    • 2017
  • Compared to metal, CFRP has excellent mechanical characteristics in terms of intensity, hardness, and heat resistance as well as its light weight that it is used widely in various fields. Therefore, this material has been used recently in the aerospace field. On the other hand, the material has shortcomings in terms of its extreme vulnerability to damage occurring internally from an external impact. This study examined the intensity up to its destruction from repeated use with the internal impact of a CFRP laminated plate that had also been exposed to external impact obtain design data for the external plate of aircraft used in the aerospace field. For the experimental method, regarding the quasi-isotopic type CFRP specimen and orthotropic CFRP specimen that are produced with a different layer structure, steel spheres with a diameter of 5 mm were collided to observe the resulting impact damage. Through a 3-point flexural fatigue experiment, the progress of internal layer separation and impact damage was observed. Measurements of the flexural fatigue strength after the flexural fatigue experiment until internal damage occurs and the surface impacted by the steel spheres revealed the quasi-isotopic layer structure to have a higher intensity for both cases.

Hydrogenated a-Si TFT Using Ferroelectrics (비정질실리콘 박막 트랜지스터)

  • Hur Chang-Wu
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.3
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    • pp.576-581
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    • 2005
  • In this paper. the a-Si:H TFT using ferroelectric of $SrTiO_3$ as a gate insulator is fabricated on glass. High k gate dielectric is required for on-current, threshold voltage and breakdown characteristics of TFT Dielectric characteristics of ferroelectric are superior to $SiO_2$ and $Si_3N_4$. Ferroelectric increases on-current and decreases threshold voltage of TFT and also ran improve breakdown characteristics.$SrTiO_4$ thin film is deposited by e-beam evaporation. Deposited films are annealed for 1 hour in N2 ambient at $150^{\circ}C\~600^{\circ}C$. Dielectric constant of ferroelectric is about 60-100 and breakdown field is about IMV/cm. In this paper, the TFT using ferroelectric consisted of double layer gate insulator to minimize the leakage current. a-SiN:H, a-Si:H (n-type a-Si:H) are deposited onto $SrTiO_3$ film to make MFNS(Metal/ferroelectric/a-SiN:H/a-Si:H) by PECVD. In this paper, TFR using ferroelectric has channel length of$8~20{\mu}m$ and channel width of $80~200{\mu}m$. And it shows that drain current is $3.4{\mu}A$at 20 gate voltage, $I_{on}/I_{off}$ is a ratio of $10^5\~10^8,\;and\;V_{th}$ is$4\~5\;volts$, respectively. In the case of TFT without having ferroelectric, it indicates that the drain current is $1.5{\mu}A$ at 20gate voltage and $V_{th}$ is $5\~6$ volts. If properties of the ferroelectric thin film are improved, the performance of TFT using this ferroelectric thin film can be advanced.

Strategies for Development of Cultural Products Design for Promotion of Cultural Tourism Festivals - Focusing on utilization of local cultural resources - (문화관광축제 활성화를 위한 문화상품 디자인 개발 전략 연구(제 1보) - 지역문화자원 활용을 중심으로 -)

  • Chung, Kyung-Hee;Lee, Mi-Sook
    • Journal of the Korean Society of Costume
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    • v.59 no.7
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    • pp.17-33
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    • 2009
  • The purpose of this study was to get some pieces of prior information to eventually develop high value-added fashion cultural products design using local cultural resources, to promote the cultural tourism festival. For this purpose, this study is carried out the investigation of cultural product stores and visitors' questionnaire survey. The subjects of this study were festivals which were selected as cultural tourism festival by the Ministry of Culture, Sports and Tourism from 2000 to 2008. Of them, six festivals were finally selected but food festival was excluded. The results of this study were as follows; First, the store survey was conduced to analyze the situation of the products of cultural tourism festival. The most frequent product was accessories. And a T-shirt was found to be sold every festival probably because it was the most popular item and basic item which people could buy without burden. While the most diverse kinds of products were found in the Andong, the Jinju and Gangjin were found not to develop various products. In the design motif used for cultural products, most products did not use festival or local image. The highest use of the festival and local image was found in Gangjin and Muju. The Andong and Chungju were found to sell very common products buying anywhere rather than products using local cultural resources or image. In the material of cultural products, most products use metal. And In the price of cultural products, 10,000-30,000 won was found highest. Second, the purchase conditions of cultural tourism festival visitors were examined. The visiting goal and companion of visitors was found to vary with the type of cultural tourism festival. The types of visitors were also found to have an effect on the choice of items in the purchase of cultural products sold in the festival. Only one third of respondents responded buying one and more cultural products. The purchase rate was found high in the festival where cultural product items were various and there were many products symbolizing festival or region. The most purchased item was a mobile phone hanger and the amount of purchasing cultural products was 10,000-30,000 won. The reason not to purchase cultural products was dissatisfaction with utility, originality, possibility of a present, symbolism, and price. The most important attribute in the purchase of cultural products was design, followed by symbolism, price, originality, and innovation. The highly preferred product group included clothing, miscellaneous goods, and accessories. Specifically, T-shirt was found highest. Based on these research results, it was found that the design strategy for the cultural products development should consider both regional and festival images. The items and designs of the cultural products should reflect visitors' characteristics and the price zone should be varied.

Oxygen Permeation Properties of La0.7Sr0.3Co0.3Fe0.7O3-δ Membrane (La0.7Sr0.3Co0.3Fe0.7O3-δ 분리막의 산소투과특성)

  • Son, Sou Hwan;Kim, Jong-Pyo;Park, Jung Hoon;Lee, Yongtaek
    • Korean Chemical Engineering Research
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    • v.47 no.3
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    • pp.310-315
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    • 2009
  • Perovskite-type ceramic powder, $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$, have been synthesized successfully by the citrate method. As a result of TGA for precursor, metal-citrate complex in precursor was decomposed in the temperature range of $150{\sim}650^{\circ}C$. XRD analysis showed the single perovskite structure was observed over $1,000^{\circ}C$ without impurities. Typical dense membrane with 1.6 mm thickness has been prepared using as-prepared powder by pressing unilaterally and sintering at $1,300^{\circ}C$. The electrical conductivity of $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$ membrane increased with increasing temperature at atmosphere of air and then decreased over $600^{\circ}C$ due to oxygen loss from the crystal lattice. The oxygen flux of $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$ membrane in the range of 700 to $950^{\circ}C$ increased with the increasing temperature from 0.045 to $0.415ml/cm^2{\cdot}min$. The activation energy for oxygen permeation was calculated to be 89.17 kJ/mol.

Fabrication and Characteristics of a Varactor Diode for UHF TV Tuner Operated within Low Tuning Voltage (저전압 UHF TV 튜너용 바렉터 다이오드의 제작 및 특성)

  • Kim, Hyun-Sik;Moon, Young-Soon;Son, Won-Ho;Choi, Sie-Young
    • Journal of Sensor Science and Technology
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    • v.23 no.3
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    • pp.185-191
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    • 2014
  • The width of depletion region in a varactor diode can be modulated by varying a reverse bias voltage. Thus, the preferred characteristics of depletion capacitance can obtained by the change in the width of depletion region so that it can select only the desirable frequencies. In this paper, the TV tuner varactor diode fabricated by hyper-abrupt profile control technique is presented. This diode can be operated within 3.3 V of driving voltage with capability of UHF band tuning. To form the hyperabrupt profile, firstly, p+ high concentration shallow junction with $0.2{\mu}m$ of junction depth and $1E+20ions/cm^3$ of surface concentration was formed using $BF_2$ implantation source. Simulation results optimized important factors such as epitaxial thickness and dose quality, diffusion time of n+ layer. To form steep hyper-abrupt profile, Formed n+ profile implanted the $PH_3$ source at Si(100) n-type epitaxial layer that has resistivity of $1.4{\Omega}cm$ and thickness of $2.4{\mu}m$ using p+ high concentration Shallow junction. Aluminum containing to 1% of Si was used as a electrode metal. Area of electrode was $30,200{\mu}m^2$. The C-V and Q-V electric characteristics were investigated by using impedance Analyzer (HP4291B). By controlling of concentration profile by n+ dosage at p+ high concentration shallow junction, the device with maximum $L_F$ at -1.5 V and 21.5~3.47 pF at 0.3~3.3 V was fabricated. We got the appropriate device in driving voltage 3.3 V having hyper-abrupt junction that profile order (m factor) is about -3/2. The deviation of capacitance by hyper-abrupt junction with C0.3 V of initial capacitance is due to the deviation of thermal process, ion implantation and diffusion. The deviation of initial capacitance at 0.3 V can be reduced by control of thermal process tolerance using RTP on wafer.

Gentiopicroside Ameliorates the Progression from Hepatic Steatosis to Fibrosis Induced by Chronic Alcohol Intake

  • Yang, Hong-Xu;Shang, Yue;Jin, Quan;Wu, Yan-Ling;Liu, Jian;Qiao, Chun-Ying;Zhan, Zi-Ying;Ye, Huan;Nan, Ji-Xing;Lian, Li-Hua
    • Biomolecules & Therapeutics
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    • v.28 no.4
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    • pp.320-327
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    • 2020
  • In current study, we aimed to investigate whether the gentiopicroside (GPS) derived from Gentiana manshurica Kitagawa could block the progression of alcoholic hepatic steatosis to fibrosis induced by chronic ethanol intake. C57BL/6 mice were fed an ethanol-containing Lieber-DeCarli diet for 4 weeks. LX-2 human hepatic stellate cells were treated with GPS 1 h prior to transforming growth factor-β (TGF-β) stimulation, and murine hepatocyte AML12 cells were pretreated by GPS 1 h prior to ethanol treatment. GPS inhibited the expression of type I collagen (collagen I), α-smooth muscle actin (α-SMA) and tissue inhibitor of metal protease 1 in ethanol-fed mouse livers with mild fibrosis. In addition, the imbalanced lipid metabolism induced by chronic ethanol-feeding was ameliorated by GPS pretreatment, characterized by the modulation of lipid accumulation. Consistently, GPS inhibited the expression of collagen I and α-SMA in LX-2 cells stimulated by TGF-β. Inhibition of lipid synthesis and promotion of oxidation by GPS were also confirmed in ethanol-treated AML12 cells. GPS could prevent hepatic steatosis advancing to the inception of a mild fibrosis caused by chronic alcohol exposure, suggesting GPS might be a promising therapy for targeting the early stage of alcoholic liver disease.

Thickness Evaluation of the Aluminum Using Pulsed Eddy Current (펄스 와전류를 이용한 알루미늄 두께 평가)

  • Lee, Jeong-Ki;Suh, Dong-Man;Lee, Seung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.1
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    • pp.15-19
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    • 2005
  • Conventional eddy current testing has been used for the detection of the defect-like fatigue crack in the conductive materials, such as aluminum, which uses a sinusoidal signal with very narrow frequency bandwidth, Whereas, the pulsed eddy current method uses a pulse signal with a broad bandwidth. This can allow multi-frequency eddy current testing, and the penetration depth is greater than that of the conventional eddy current testing. In this work, a pulsed eddy current instrument was developed for evaluating the metal loss. The developed instrument was composed of the pulse generator generating the maximum square pulse voltage of 40V, an amplifier controlled up to 52dB, an A/D converter of 16 bit and the sampling frequency of 20 MHz, and an industrial personal computer operated by the Windows program. A pulsed eddy current probe was designed as a pancake type in which the sensing roil was located inside the driving roil. The output signals of the sensing roil increased rapidly wich the step pulse driving voltage かn off, and the latter part of the sensing coil output voltage decreased exponentially with time. The decrement value of the output signals increased as the thickness of the aluminum test piece increased.

Nanocomposite Water Treatment Membranes: Antifouling Prospective (수처리용 나노복합막: 방오의 관점에서)

  • Kim, Soomin;Patel, Rajkumar
    • Membrane Journal
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    • v.30 no.3
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    • pp.158-172
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    • 2020
  • In the aspect of saving energy and water, facilitating the separation membrane for the water treatment has been rising recently as one of the possible solutions. However, microbial biofouling effect is the biggest obstacle that hinders reaching higher permeability over a prolonged period of nanofiltration operation. To solve this problem and fully utilize the filtration membranes with enhanced performance, largely two kinds of solutions are studied and the first and the most commonly mentioned type is the one using the silver nanoparticles. Since silver nanoparticles are important to be well tailored on membrane surface, various methods have been applied and suggested. Using silver nanoparticles however also has the drawbacks or possible toxicity risks, raising the need for other types of utilizing non silver particles to functionalize the membrane, such as copper, graphene or zinc oxides, and amine moieties. Each attempt included in either kind has produced some notable results in killing, preventing, or repelling the bacteria while at the same time, left some unsolved points to be evaluated. In this review, the effects of metal nanoparticles and other materials on the antifouling properties of water treatment membranes are summarized.

Preconcentration and Determination of Trace Cobalt and Nickel by the Adsorption of Metal-PDC Complexes on the Anion-Exchange Resin Suspension (금속-PDC 착물의 음이온교환 수지 상 흡착에 의한 흔적량 코발트와 니켈의 동시 예비농축 및 정량)

  • Han, Chul-Woo;In, Gyo;Choi, Jong-Moon;Kim, Sun Tae;Kim, Young-Sang
    • Analytical Science and Technology
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    • v.13 no.5
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    • pp.608-615
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    • 2000
  • A determination method of trace nickel and cobalt in water samples was studied and developed by adsorbing their complexes on ion exchange resin suspension. The analytical ions were formed as complexes with a ligand of APDC (ammonium pyrrolidinedithiocarbamate) and adsorbed on anion exchange resin of Dowex 2-X8. After the suspension was filtered out with membrane filter, the complexes were dissolved in HCl solution by an ultrasonic vibrator for ET-AAS determination. Several conditions were optimized as followings. pH of sample solution: 5.0, amount of ligand APDC: more than 430 times in mole ratio, the type and concentration of acid: 0.1 M HCl, and vibration time: 7 minutes. The addition of palladium in the HCl solution could improve the reproducibility and sensitivity by a matrix modification in the absorbance measurement. This procedure was applied for the analysis of three kinds of real water samples. The detection limits equivalent to 3 times standard deviation of blank were Co 0.36 ng/mL and Ni 0.27 ng/mL and recoveries in spiked samples were 99-102% for cobalt and 100-105% for nickel.

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A Survey Report on the Polymetallic Mineralization in the Oyon Mineralized District, Central Peru (페루 중부 오욘 다중금속 광화작용에 대한 조사보고)

  • Lee, Jaeho;Kim, Injoon;Nam, Hyeong-tae
    • Economic and Environmental Geology
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    • v.50 no.1
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    • pp.73-83
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    • 2017
  • The surveyed mines are located in a polymetallic vein, replacement, and skarn mineral district in the central Andes of Peru. Iscaycruz, which includes underground and open pit mines that produce zinc and lead concentrates, was the largest mineral deposit of an important group of base metal deposits in the Andes of central Peru. The deposits are sub-vertical seams of polymetallic ores(Zn, Cu, and Pb). These seams are hosted by Jurassic and Cretaceous sedimentary rock formation. The intrusion of igneous rocks in these formations originated metallic deposits of metasomatic and skarn types. The Raura mine is composed of polymetallic deposit of veins and replacement orebodies. The main sedimentary unit in the area is Cretaceous Machay Limestone. The Raura depression contains several orebodies each with different mineralization: predominantly Pb-Zn bearing Catuvo orebody; Ag-rich galena-bearing Lake Ninacocha orebody; Cu-Ag bearing Esperanza and Restauradora orebody. Huaron is a hydrothermal polymetallic deposit of silver, lead, zinc, and copper mineralization hosted within structures likely related to the intrusion of monzonite dikes, principally located within the Huaron anticline. Mineralization is encountered in veins parallel to the main fault systems, in replacement bodies known as "mantos" associated with the calcareous sections of the conglomerates and other favourable stratigraphic horizons, and as dissemination in the monzonitic intrusions at vein intersections.