• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.301-301
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• 2011

최근 고밀도 메모리 반도체의 재료와 빠른 응답을 요구하는 나노입자를 이용한 비휘발성 메모리 소자의 제작에 대한 연구가 활발히 진행되고 있다. 그에 따른 기존의 플래쉬 메모리가 가지는 문제점을 개선하기 위해서 균일하고 규칙적으로 분포하는 새로운 나노소재의 개발과 비휘발성, 고속 동작, 고집적도, 저전력 소자의 공정기술이 요구되고 있다. 또한 부유게이트에 축적되는 저장되는 전하량을 증가시키기 위한 새로운 소자구조 개발이 필요하다. 한편, 실리 사이드 계열의 나노입자는 금속 나노입자와 달리 현 실리콘 기반의 반도체 공정에서 장점을 가지고 있다. 따라서 본 연구에서는 화합물 중에서 비휘발성 메모리 장치의 전기적 특성을 향상 시킬 수 있는 실리사이드 계열의 바나듐 실리사이드(V3Si) 박막을 열처리 과정을 통하여 수 nm 크기의 나노입자로 제작하였다. 소자의 제작은 p-Si기판에 실리콘산화막 터널층(5 nm 두께)을 건식 산화법으로 성장 후, 바나듐 실리사이드 금속박막을 RF 마그네트론 스퍼터 시스템을 이용하여 4~6 nm 두께로 터널 베리어 위에 증착하고, 그 위에 초고진공 마그네트론 스퍼터링을 이용하여 SiO2 컨트롤 산화막층 (20 nm)을 형성시켰다. 여기서 V3Si 나노입자 형성을 위해 급속 열처리법으로 질소 분위기에서 800$^{\circ}C$로 5초 동안 열처리하여 하였으며, 마지막으로 열 기화 시스템을 통하여 알루미늄 전극(직경 200 ${\mu}m$, 두께 200 nm)을 증착하여 소자를 제작하였다. 제작된 구조는 금속 산화막 반도체구조를 가지는 나노 부유게이트 커패시터이며, 제작된 시편은 투사전자현미경을 이용하여 나노입자의 크기와 균일성을 확인했다. 소자의 전기적인 측정을 E4980A capacitor parameter analyzer와 Agilent 81104A pulse pattern generator system을 이용한 전기용량-전압 측정을 통해 전하저장 효과 및 메모리 동작 특성들을 분석하고, 열처리 조건에 따라 형성되는 V3Si 의 조성을 엑스선 광전자 분광법을 이용하여 확인하였다.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.1-6
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• 2008

Block copolymers spontaneously assemble into various nanoscale structures such as spheres, cylinders, and lamellar structures according to the relative volumn ratio of each macromolecular block and their overall molecular weights. The self-assembled structures of block copolymer have been extensively investigated for the applications such as nanocomposites, photonic crystals, nanowires, magnetic-storage media, flash memory devices. However, the naturally formed nanostructures of block copolymers contain a high density of defects such that the practical applications for nanoscale devices have been limited. For the practical application of block copolymer nanostructures, a robust process to direct the assembly of block copolymers in thin film geometry is required to be established. To exploit self-assembly of block copolymer for the nanotechnology, it is indispensible to fabricate defect-free self-assembled nanostructure over an arbitrarily large area.

• Journal of the Korean Wood Science and Technology
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• v.48 no.4
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• pp.431-449
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• 2020

Structural property of most hydrogels is soft, resulting in low mechanical performance that limits their usage in the biomedical applications. For overcoming the drawback, cellulose nanocrystals (CNCs) were adopted in this study. Effects of CNCs on characteristics and drug delivery performance of poly (vinyl alcohol) based hydrogels were explored. FT-IR results showed that the fabricated hydrogels had semi-IPN (semi-interpenetrating polymer network) by formation of acetal and aldehyde bridge. Water absorption and swelling ratio decreased with increasing CNCs content, and the hydrogels with CNCs showed better viscoelastic performance than the without CNCs. Also, CNCs mostly improved the ability of the hydrogel to absorb the drug and the sustainability of the drug release. These results demonstrated that incorporating CNCs into the hydrogel systems can be a good alternative to improve drug delivery performance and mechanical property of the hydrogels.

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.268-274
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• 2018

In this study we suggest a humidity-sensitive color sensor using a one-dimensional photonic crystal and Hong Kong University of Science and Technology-1 (HKUST-1), which is a metal-organic framework (MOF) substance. One-dimensional photonic crystals have a photonic band gap, due to a periodic refractive-index change, and block and reflect light components in a specific wavelength band. The refractive index of HKUST-1 differs in dry and humid environments. Herein we designed a sensor using the presence of the photonic band gap, with FDTD simulation. As a result of optical analysis, the color conversion of the reflected light was superior to the color conversion of the transmitted light. When the center wavelength of the photonic band gap was 550 nm, the maximum peak value of the wet environment increased by a factor of about 9.5 compared to the dry environment, and the color conversion from achromatic to green was excellent as a sensor. The results of this study suggest the application of MOF materials to moisture sensors, and the nanostructure design of MOF materials will expand the applications to industrial devices.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.38.1-38.1
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• 2011

최근 중동정세의 변화와 유류 소비의 증가에 따른 유가의 급등과, 일본 지진사태로 일어난 원자력 발전의 안정성에 대한 문제로 인하여 안전하고 깨끗하게 에너지를 생산할 수 있는, 저탄소 녹색성장을 구현할 수 있는 신재생 에너지에 관련된 연구에 많은 관심이 모아지고 있다. 특히 태양광 에너지를 전기로 변환하여 사용하는 것은 최근 가장 큰 관심사 중 하나이다. 나노결정 Si (nc-Si) 박막은 이러한 광전자 산업 및 태양 에너지 분야에서의 폭넓은 응용 가능성으로 많은 연구가 진행되고 있다. 이러한 nc-Si 박막의 발광 특성은 비정질 박막내 Si 나노결정에 기인한 양자제한효과(quantum confinement effect)에 의한 것으로 알려져 있다. 본 연구에서는 증착시 기판에 AC (alternating current) Bias를 인가하여 PE CVD 기법으로 nc-Si:H 박막을 증착하였다. H2와 SiH4를 각기 45, 20 sccm으로, 100 W의 RF 전압을 주어 플라즈마를 생성하였으며, 60~900 Hz의 주파수 범위에서 60 V의 Bias를 인가하여 박막을 증착하였다. 이들 박막의 결정 크기, 결정화도, 나노 구조 및 광학적, 화학적, 기계적 특성을 XRD, FT-IR, Raman spectroscopey, AFM, PL, Nano indenter 등을 사용하여 조사하였으며, 기판에 인가된 전압과 주파수에 따른 결정크기와 박막의 광학적 특성과 상관관계를 고찰하였다. Bias 전압에 따라 ~1에서 ~4 nm의 크기를 갖는 나노 크리스탈이 생성 되었으며, 최고 10%의 나노결정 분율을 가지는 박막을 증착하였다. 이는 광학적 특성에도 영향을 주어 PL (photoluminescence)의 피크는 470~710 nm의 영역에서 관찰되었다. 또한 AC-Bias의 영향으로 박막 내 응력 해소에도 영향을 주어 박막내 존재하는 응력이 결정에 미치는 영향도 알 수 있었다. 이번 발표에선 증착 조건에 따른 박막의 나노구조 및 광학적 특성의 변화와 이들 간의 상관관계를 발표하고자 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.4
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• pp.374-381
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• 2024

This paper delves into the application of the short-wave infrared (SWIR) region, with a focus on the synthesis and optical characteristics of silver sulfide (Ag₂S) nanostructures. SWIR offers advantages such as reduced damage to biological tissues and enhanced optical transparency, making it valuable across various domains. The study introduces three distinct synthesis methods, each showcasing the ability to obtain nanostructures with improved optical properties. These research findings open up the possibility of providing tailored solutions in detection, imaging, and other applications by controlling the size and ligands of Ag₂S nanoparticles. This paper provides new insights into the utilization of Ag₂S in the SWIR region, which is expected to foster advancements in future technologies.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.518-527
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• 2015

In this study, nanocomposite mats consisting of cellulose nanocrystals (CNCs) and poly(lactic acide) (PLA) were electrospun from a suspension mixture consisting of tetrahydrofuran at room temperature. Morphology study showed that fibers of electrospun composite mats were aligned in three dimensional surface along the fiber long-axis. Average diameter of the electrospun fibers decreased with an increase in the CNC loading level. Tensile strength of the electrospun fibers mat decreased with an increase in the CNC loading level because of bead formation in the formed fibers and low interfacial bond strength between PLA and CNC. Meanwhile, thermal stability of the electrospun nanocomposite mats was effectively improved as the amount of CNC increased.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.730-739
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• 2015

Various cellulose nanofibers (CNF) with different morphology and chemical properties were prepared for the reinforcement of sheet of paper mulberry bast fiber. Lignocellulose nanofiber (LCNF), Holocellulose nanofiber (HCNF), alkali-treated HCNF (AT-HCNF), TEMPO-oxidated nanofiber (TEMPO-NF) and cellulose nanocrystal (CNF) were prepared and their addition effect on the properties of sheet of paper mulberry bast fiber were investigated. Air permeability, surface smoothness, and tensile properties were improved by increasing CNF addition. Its improvement may be due to the CNF deposited between and on paper mulberry bast fibers, which was confirmed by SEM observation.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.376-384
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• 2014

This study investigated the effect of nanocellulose, such as microfibrillated cellulose (MFC) and cellulose nanocrystal (CNC), and aminated starch on tensile property and thermal stability of plasticized starch film. Glycerol (23 wt%) was used as a plasticizer and nanocelluloses of 1-30 parts per hundred parts of resin (phr) in the basis of plasticized starch were added. Tensile strength and elastic modulus increased with increasing nanocellulose addition amount, whereas elongation at break decreased. Tensile properties of MFC-reinforced starch film were higher than those of CNC-reinforced film. Optimum addition amount of aminated starch, which is commonly used for paper sizing, to improve tensile property of film, was found to be 5%. And 1% addition of aminated starch showed the best effect in the improvement of tensile property of the film. Thermal stability was improved with the addition of MFC to plasticized starch film with and without aminated starch.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.791-796
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• 2017

In this study, the combustion characteristics of paraffin blended fuel on aluminum particle size were investigated. The combustion experiments were carried out using aluminum particles with an average particle size of 100 nm and $8{\mu}m$ and microcrystalline paraffin wax (Sasol 0907). A series of comparison was conducted on the regression rate, the pressure curve and the characteristic velocity of pure paraffin and paraffin blended fuels with aluminum particles. It was found that the micro-sized particles enhance the regression rate as the oxidizer mass flux increased. However, the nano-sized particles decrease the regression rate as the oxidizer mass flux is increased.