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        검색결과 35

        1.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cellular myxoma is an uncommon type of myxoid benign tumor, predominantly occurring in adult female patients aged >40 years. This report aims to document a case of cellular myxoma that occurred in the buccal mucosa. Compared to intramuscular myxomas, cellular myxoma demonstrates hypercellularity and vascularity. Its manifestation in the soft tissue of the head and neck area is exceptionally rare. Generally, cellular myxoma manifests as a firm and immovable mass covered with normal oral mucosa, with no associated clinical symptoms. Homogenous low signal intensity on T1-weighted scans and high-signal intensity on T2-weighted magnetic resonance scans reveal cellular myxoma, as most lesions show well-defined margins and heterogeneous contrast enhancement. The significant histologic features include a focal or diffuse increase in cellularity with fibroblast-like cells and vascularity with an abundant collagenous matrix. Our presented case reflects these facts examinations, based on which a final diagnosis of cellular myxoma was made. Immunohistochemistry revealed locally and diffusely positive SMA and CD34. The clinical tendency of cellular myxoma with hypercellularity may affect the production of myxoid and collagenous substrates, and if complete resection is not performed, the possibility of local recurrence in the primarily affected region remains. Hence, complete surgical excision was performed under general anesthesia, and follow-up until a year after treatment revealed no observed recurrence. To achieve precise diagnosis and complete treatment without local recurrence, several diagnostic examinations should be considered.
        4,000원
        2.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The semiconductor industry faces physical limitations due to its top-down manufacturing processes. High cost of EUV equipment, time loss during tens or hundreds of photolithography steps, overlay, etch process errors, and contamination issues owing to photolithography still exist and may become more serious with the miniaturization of semiconductor devices. Therefore, a bottom-up approach is required to overcome these issues. The key technology that enables bottom-up semiconductor manufacturing is area-selective atomic layer deposition (ASALD). Here, various ASALD processes for elemental metals, such as Co, Cu, Ir, Ni, Pt, and Ru, are reviewed. Surface treatments using chemical species, such as self-assembled monolayers and small-molecule inhibitors, to control the hydrophilicity of the surface have been introduced. Finally, we discuss the future applications of metal ASALD processes.
        4,500원
        3.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Thermoelectric materials and devices are energy-harvesting devices that can effectively recycle waste heat into electricity. Thermoelectric power generation is widely used in factories, engines, and even in human bodies as they continuously generate heat. However, thermoelectric elements exhibit poor performance and low energy efficiency; research is being conducted to find new materials or improve the thermoelectric performance of existing materials, that is, by ensuring a high figure-of-merit (zT) value. For increasing zT, higher σ (electrical conductivity) and S (Seebeck coefficient) and a lower к (thermal conductivity) are required. Here, interface engineering by atomic layer deposition (ALD) is used to increase zT of n-type BiTeSe (BTS) thermoelectric powders. ALD of the BTS powders is performed in a rotary-type ALD reactor, and 40 to 100 ALD cycles of ZnO thin films are conducted at 100oC. The physical and chemical properties and thermoelectric performance of the ALD-coated BTS powders and pellets are characterized. It is revealed that electrical conductivity and thermal conductivity are decoupled, and thus, zT of ALD-coated BTS pellets is increased by more than 60% compared to that of the uncoated BTS pellets. This result can be utilized in a novel method for improving the thermoelectric efficiency in materials processing.
        4,000원
        4.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Thermoelectric materials can reversely convert heat and electricity into each other; therefore, they can be very useful for energy harvesting from heat waste. Among many thermoelectrical materials, SnSe exhibits outstanding thermoelectric performance along the particular direction of a single crystal. However, single-crystal SnSe has poor mechanical properties and thus it is difficult to apply for mass production. Therefore, polycrystalline SnSe materials may be used to replace single-crystal SnSe by overcoming its inferior thermoelectric performance owing to surface oxidation. Considerable efforts are currently focused on enhancing the thermoelectric performance of polycrystalline SnSe. In this study, we briefly review various enhancement methods for SnSe thermoelectric materials, including doping, texturing, and nano-structuring. Finally, we discuss the future prospects of SnSe thermoelectric powder materials.
        4,000원
        5.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The SnSe single crystal shows an outstanding figure of merit (ZT) of 2.6 at 973 K; thus, it is considered to be a promising thermoelectric material. However, the mass production of SnSe single crystals is difficult, and their mechanical properties are poor. Alternatively, we can use polycrystalline SnSe powder, which has better mechanical properties. In this study, surface modification by atomic layer deposition (ALD) is chosen to increase the ZT value of SnSe polycrystalline powder. SnSe powder is ground by a ball mill. An ALD coating process using a rotary-type reactor is adopted. ZnO thin films are grown by 100 ALD cycles using diethylzinc and H2O as precursors at 100oC. ALD is performed at rotation speeds of 30, 40, 50, and 60 rpm to examine the effects of rotation speed on the thin film characteristics. The physical and chemical properties of ALD-coated SnSe powders are characterized by scanning and tunneling electron microscopy combined with energy-dispersive spectroscopy. The results reveal that a smooth oxygenrich ZnO layer is grown on SnSe at a rotation speed of 30 rpm. This result can be applied for the uniform coating of a ZnO layer on various powder materials.
        4,000원
        6.
        2019.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Aluminum nitride (AlN) has versatile and intriguing properties, such as wide direct bandgap, high thermal conductivity, good thermal and chemical stability, and various functionalities. Due to these properties, AlN thin films have been applied in various fields. However, AlN thin films are usually deposited by high temperature processes like chemical vapor deposition. To further enlarge the application of AlN films, atomic layer deposition (ALD) has been studied as a method of AlN thin film deposition at low temperature. In this mini review paper, we summarize the results of recent studies on AlN film grown by thermal and plasma enhanced ALD in terms of processing temperature, precursor type, reactant gas, and plasma source. Thermal ALD can grow AlN thin films at a wafer temperature of 150~550 oC with alkyl/amine or chloride precursors. Due to the low reactivity with NH3 reactant gas, relatively high growth temperature and narrow window are reported. On the other hand, PEALD has an advantage of low temperature process, while crystallinity and defect level in the film are dependent on the plasma source. Lastly, we also introduce examples of application of ALD-grown AlN films in electronics.
        4,200원
        7.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Atomic layer deposition (ALD) is widely used as a tool for the formation of near-atomically flat and uniform thin films in the semiconductor and display industries because of its excellent uniformity. Nowadays, ALD is being extensively used in diverse fields, such as energy and biology. By controlling the reactivity of the surface, either homogeneous or inhomogeneous coating on the shell of nanostructured powder can be accomplished by the ALD process. However, the ALD process on the powder largely depends on the displacement of powder in the reactor. Therefore, the technology for the fluidization of the powder is very important to redistribute its position during the ALD process. Herein, an overview of the three types of ALD reactors to agitate or fluidize the powder to improve the conformality of coating is presented. The principle of fluidization its advantages, examples, and limitations are addressed.
        4,000원
        8.
        2018.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        TaNx film is grown by plasma enhanced atomic layer deposition (PEALD) using t-butylimido tris(dimethylamido) tantalum as a metalorganic source with various reactive gas species, such as N2+H2 mixed gas, NH3, and H2. Although the pulse sequence and duration are the same, aspects of the film growth rate, microstructure, crystallinity, and electrical resistivity are quite different according to the reactive gas. Crystallized and relatively conductive film with a higher growth rate is acquired using NH3 as a reactive gas while amorphous and resistive film with a lower growth rate is achieved using N2+H2 mixed gas. To examine the relationship between the chemical properties and resistivity of the film, X-ray photoelectron spectroscopy (XPS) is conducted on the ALD-grown TaNx film with N2+H2 mixed gas, NH3, and H2. For a comparison, reactive sputter-grown TaNx film with N2 is also studied. The results reveal that ALD-grown TaNx films with NH3 and H2 include a metallic Ta-N bond, which results in the film’s higher conductivity. Meanwhile, ALD-grown TaNx film with a N2+H2 mixed gas or sputtergrown TaNx film with N2 gas mainly contains a semiconducting Ta3N5 bond. Such a different portion of Ta-N and Ta3N5 bond determins the resistivity of the film. Reaction mechanisms are considered by means of the chemistry of the Ta precursor and reactive gas species.
        4,000원
        9.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon nanofibers (CNF) are widely used as active agents for electrodes in Li-ion secondary battery cells, supercapacitors, and fuel cells. Nanoscale coatings on CNF electrodes can increase the output and lifespan of battery devices. Atomic layer deposition (ALD) can control the coating thickness at the nanoscale regardless of the shape, suitable for coating CNFs. However, because the CNF surface comprises stable C–C bonds, initiating homogeneous nuclear formation is difficult because of the lack of initial nucleation sites. This study introduces uniform nucleation site formation on CNF surfaces to promote a uniform SnO2 layer. We pretreat the CNF surface by introducing H2O or Al2O3 (trimethylaluminum + H2O) before the SnO2 ALD process to form active sites on the CNF surface. Transmission electron microscopy and energy-dispersive spectroscopy both identify the SnO2 layer morphology on the CNF. The Al2O3-pretreated sample shows a uniform SnO2 layer, while island-type SnOx layers grow sparsely on the H2Opretreated or untreated CNF.
        4,000원
        10.
        2017.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Insulating TaNx films were grown by plasma enhanced atomic layer deposition using butylimido tris dimethylamido tantalum and N2+H2 mixed gas as metalorganic source and reactance gas, respectively. Crossbar devices having a Pt/TaNx/Pt stack were fabricated and their electrical properties were examined. The crossbar devices exhibited temperature-dependent nonlinear I (current) - V (voltage) characteristics in the temperature range of 90-300 K. Various electrical conduction mechanisms were adopted to understand the governing electrical conduction mechanism in the device. Among them, the Poole- Frenkel emission model, which uses a bulk-limited conduction mechanism, may successfully fit with the I - V characteristics of the devices with 5- and 18-nm-thick TaNx films. Values of ~0.4 eV of trap energy and ~20 of dielectric constant were extracted from the fitting. These results can be well explained by the amorphous micro-structure and point defects, such as oxygen substitution (ON) and interstitial nitrogen (Ni) in the TaNx films, which were revealed by transmission electron microscopy and UV-Visible spectroscopy. The nonlinear conduction characteristics of TaNx film can make this film useful as a selector device for a crossbar array of a resistive switching random access memory or a synaptic device.
        4,000원
        11.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lithium-ion batteries (LIBs) are rapidly improving in capacity and life cycle characteristics to meet the requirements of a wide range of applications, such as portable electronics, electric vehicles, and micro- or nanoelectromechanical systems. Recently, atomic layer deposition (ALD), one of the vapor deposition methods, has been explored to expand the capability of LIBs by producing near-atomically flat and uniform coatings on the shell of nanostructured electrodes and membranes for conventional LIBs. In this paper, we introduce various ALD coatings on the anode, cathode, and separator materials to protect them and improve their electrochemical and thermomechanical stability. In addition, we discuss the effects of ALD coatings on the three-dimensional structuring and conduction layer through activation of electrochemical reactions and facilitation of fluent charge collection.
        4,000원
        12.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The triboelectric property of a material is important to improve an efficiency of triboelectric generator(TEG) in energy harvesting from an ambient energy. In this study, we have studied the TEG property of a semicon-ducting SnO2 which has yet to be explored so far. As a counter triboelectric material, PET and glass are used. Verticalcontact mode is utilized to evaluate the TEG efficiency. SnO2 thin film is deposited by atomic layer deposition on bareSi wafer for various thicknesses from 5.2 nm to 34.6 nm, where the TEG output is increased from 13.9V to 73.5V. Tri-boelectric series are determined by comparing the polarity of output voltage of 2 samples among SnO2, PET, and glass.In conclusion, SnO2, as an intrinsic n-type material, has the most strong tendency to be positive side to lose the electronand PET has the most strong tendency to be negative side to get the electron, and glass to be between them. Therefore,the SnO2-PET combination shows the highest TEG efficiency.
        4,000원
        13.
        2015.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Resistance switching memory cells were fabricated using atomically dispersed Pt-SiO2 thin film prepared via RF co-sputtering. The memory cell can switch between a low-resistance-state and a high-resistance-state reversibly and reproducibly through applying alternate voltage polarities. Percolated conducting paths are the origin of the low-resistance-state, while trapping electrons in the negative U-center in the Pt-SiO2 interface cause the high-resistance-state. Intermediate resistance-states are obtained through controlling the compliance current, which can be applied to multi-level operation for high memory density. It is found that the resistance value is related to the capacitance of the memory cell: a 265-fold increase in resistance induces a 2.68-fold increase in capacitance. The exponential growth model of the conducting paths can explain the quantitative relationship of resistance-capacitance. The model states that the conducting path generated in the early stage requires a larger area than that generated in the last stage, which results in a larger decrease in the capacitance.
        4,000원
        14.
        2014.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pt nanopowder-dispersed SiO2 (SOP) films were prepared by RF co-sputtering method using Pt and SiO2 targets in Ar atmosphere. The growth rate and Pt content in the film were controlled by means of manipulating the RF power of Pt target while that of SiO2 was fixed. The roughness of the film was increased with increasing the power of Pt target, which was mainly due to the increment of the size and planar density of Pt nanopowder. It was revealed that SOP film formed at 10, 15, 20 W of Pt power contained 2.3, 2.7, and 3.0 nm of spherical Pt nanopowder, respectively. Electrical conductivity of SOP films was exponentially increased with increasing Pt power as one can expect. Interestingly, conductivity of SOP films from Hall effect measurement was greater than that from DC I-V measurement, which was explained by the significant increase of electron density.
        4,000원
        15.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 입경·비중 겸용 밭작물 곡물 선별기 개발을 위한 전 단계로서, 밭작물 곡물의 완전립과 불량립의 기하학적, 공기역학적, 마찰 특성을 측정하고, 선별기 설계에 적용하기 위한 선별 요인을 분석하였다. 측정된 곡물의 기하학적 특성 결과(길이, 폭, 두께)를 이용하여 스크린의 치수와 형상을 결정하여 선별기를 제작하여 선별시험을 한 결과 선별효율은 콩의 경우 94.7%, 커피는 92.0%, 아몬드는 74.5%, 옥수수는 90.0%로 나타났다. 측정된 곡물의 마찰 특성 결과를 이용한 고무벨트 선별 시험 결과 콩의 경우 벨트 속도 0.5 m/s, 벨트 각도 5˚ 일 때 선별효율이 88.2%로 가장 높게 나타났다. 측정된 곡물의 공기역학적 특성 결과, 종말속도는 콩의 경우 4.4∼6.0 m/s, 커피는 3.2∼4.4 m/s, 아몬드는 3.5∼5.1 m/s, 옥수수는 4.7∼6.0 m/s의 범위로 나타났다.
        4,000원
        16.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was designed to evaluate to acute oral toxicity and skin irritation of Chrysanthemum dye in Sprague-Dawley (SD) rats. SD rats were orally treated with Chrysanthemum dye at a dose of 0, 1 and 2 ml/kg body weight. After oral administration, the rats were observed for 14days. In primary skin irritation test, SD rats were dermally treated with Chrysanthemum dye and observed for 3 days. To ensure the safety of Chrysanthemum dye such as the following were observed and tested. We examined the body weight, the feed intake, the clinical signs, the ophthalmological test, the histopathological test, the mortality and skin irritation. As a result, no significant differences were found in body weight, feed intake and histopathological test between control and Chrysanthemum dye treated group. In the result of skin irritation test, Chrysanthemum dye did not induce erythema and edema after topical application. Primary irritation index was “0” in the test. Therefore, it is suggested that Chrysanthemum dye has no effect on acute toxicity and side effect in SD rats and is non-irritant material based on the score “0” of primary irritation index.
        4,000원
        17.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        국화과(Compositae)는 현화식물 중 세계에서 가장 넓게 분포하고, 쌍자엽식물 중 가장 진화된 식물분류군이며, 우리나라에는 약 300여종이 존재하는 것으로 알려져 있다. 구절초, 감국, 쑥, 쑥갓, 개미취, 참취, 곰취 등 국화과 식물들은 예로부터 민간에서 약용 및 식용 소재로써 다양하게 사용되어왔다. 본 연구는 국화 및 국화근연종 유용유전자원 선발을 통하여 육종 소재를 확대하고, 중간모본 및 신품종 육성기반을 구축하고자 DNA 마커시스템의 개발을 위해 수행되었다. 1. 화단국인 Smileball(Dendranthema grandiflorum) 품종을 사용하여 SSR-enriched library를 작성하였고, GS FLX 분석을 통해 18.83Mbp의 염기서열 결과를 얻었으며, read의 평균 길이는 280.06bp로 나타났다. 2. 단순반복염기서열(SSR) 부위를 포함하는 26,780개 clones 중 di-nucleotide motifs가 16,375개(61.5%)로 우세하였고, trinucleotide motifs(6,616개, 24.8%), tetra-nucleotide motifs(1,674개, 6.3%), penta-nucleotide motifs(1,283개, 4.8%), hexa-nucleotide motifs(693개, 2.6%) 순으로 나타났다. 3. 얻어진 di-nucleotide motifs들 중에서는, AC/CA class가 93.5%로 대부분이었고, tri-nucleotide motifs에서는 AAC class가 50.5%, tetra-nucleotide motifs는 ACGT class가 43.6%이고, pentanucleotide motif에서는 AACGT class 27.2%이며, hexa-nucleotide motif에서는 ACGATG class 21.8%였다. 4. 얻어진 염기서열 결과를 토대로 다양한 motif를 갖는 100개의 SSR 마커를 제작하였고, 차후 이를 활용하여 국화 유전자원의 다형성 및 유전자형 분석을 통해 분자유전학적 다양성 및 집단의 구조분석이 가능하고, 국화의 분자육종기반 구축을 위한 유용한 도구가 될 것 이다.
        4,000원
        18.
        2010.10 구독 인증기관·개인회원 무료
        국화에서는 파밤나방은 7~10월에 주로 발생하여 잎과 줄기, 꽃잎에 피해를 주는 해충이다. 시설에서 재배되는 국화에 대하여 파밤나방에 대한 경제적피해수준 및 요방제 수준을 추정하였다. 파밤나방의 접종시기와 접종량에 따른 수량과 관계를 조사하였다. 국화 백선을 정식후 14일과 정식후 83일(꽃눈형성기)에 파밤나방을 100주와 20주에 각각 0, 5, 10, 20, 40마리를 접종하였다. 100주에서 20마리 접종 과 40마리 접종에서 9월13일 피해엽율은 각각 58.3%, 57.6%를 나타내었다. 파밤 나방 무방제구에 대한 수량은 47,142.9본/10a이었으며 수량감소율은 72.5%로 12964.2본/10a 였다. 꽃눈형성기에 국화 파밤나방의 유충밀도와 수량감소율과의 상관관계식은 Y = 18.5X-13.5 (R2=0.9661)의 회귀식을 얻을 수 있었고 파밤나방 접종밀도에 따른 피해엽율과 수량감소율의 관계는 정의 상관관계가 있는 것으로 나타났다. 경제적허용수준은 20주당 유충 1마리이며 방제가 필요한 수준은 20주 당 유충 0.8마리였다.
        19.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sucking spray type liquid dispenser does to ply piston by exclusive use cylinder, did so that dispenser may can do pumping, and control sucking and interception of dispenser by sucking piston and interception node in main cylinder interior and control coating emperor's the spray amount more minutely in main cylinder, various coating emperors of low viscosity so that fixed quantity spray is possible spray type liquid dispenser be. In this paper, spray angle and theoretically cover extent in actuality cover extent is difference, spray form, spray air, spray high, over lap extent according to use usage becomes different and actuality cover extent applies over lap 20[%], and succeed to reduce error of cover extent maximum theoretically with actuality cover extent and got near result in cover extent of 10[%] withins.
        4,000원
        20.
        1998.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Microstructure and mechanical properties were examined on rapidly solidified Al-8wt%Fe alloy. High temperature strength test was also undertaken, and it is shown that the refinement in microstructure resulting from extremely rapid cooling rates gives rise to improved high temperature strength, but the elongation to fracture of this material decreases with increasing temperature, particularly in the temperature range up to 30. Specimens heat-treated for 100 hrs were analyzed with TEM micrographs to understand the thermal stability of this material.
        4,000원
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