• Korean Journal of Materials Research
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• v.20 no.11
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• pp.606-610
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• 2010

Films consisting of a silicon quantum dot superlattice were fabricated by alternating deposition of silicon rich silicon nitride and $Si_3N_4$ layers using an rf magnetron co-sputtering system. In order to use the silicon quantum dot super lattice structure for third generation multi junction solar cell applications, it is important to control the dot size. Moreover, silicon quantum dots have to be in a regularly spaced array in the dielectric matrix material for in order to allow for effective carrier transport. In this study, therefore, we fabricated silicon quantum dot superlattice films under various conditions and investigated crystallization behavior of the silicon quantum dot super lattice structure. Fourier transform infrared spectroscopy (FTIR) spectra showed an increased intensity of the $840\;cm^{-1}$ peak with increasing annealing temperature due to the increase in the number of Si-N bonds. A more conspicuous characteristic of this process is the increased intensity of the $1100\;cm^{-1}$ peak. This peak was attributed to annealing induced reordering in the films that led to increased Si-$N_4$ bonding. X-ray photoelectron spectroscopy (XPS) analysis showed that peak position was shifted to higher bonding energy as silicon 2p bonding energy changed. This transition is related to the formation of silicon quantum dots. Transmission electron microscopy (TEM) and electron spin resonance (ESR) analysis also confirmed the formation of silicon quantum dots. This study revealed that post annealing at $1100^{\circ}C$ for at least one hour is necessary to precipitate the silicon quantum dots in the $SiN_x$ matrix.

• Macromolecular Research
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• v.17 no.12
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• pp.995-1002
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• 2009

Luminescent polynorbornene (PNB)/quantum dot (CdSe@ZnS; QD) composite nanorods and nanotubes were successfully prepared using anodic aluminum oxide (AAO) membranes of various pore sizes as templates. To protect QDs with high quantum yield from quenching during the phosphoric acid treatment used to remove the AAO templates, chemically stable and optically clear norbornene-maleic anhydride copolymers (P(NB-r-MA)) were employed as a capping agent for QDs. The amine-terminated QDs reacted with maleic anhydride moieties in P(NB-r-MA) to form PNB-grafted QDs. The chemical- and photo-stability of QDs encapsulated with PNB copolymers were investigated by photoluminescence (PL) spectroscopy. By varying the pore size of the AAO templates from 40 to 380 urn, PNB/QD composite nanorods or nanotubes were obtained with a good dispersion of QDs in the PNB matrix.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.114-118
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• 2022

The stabilized all-solid-state battery structure indicate a fundamental alternative to the development of next-generation energy storage devices. Existing liquid electrolyte structures severely limit battery stability, creating safety concerns due to the growth of Li dendrites during rapid charge/discharge cycles. In this study, a low-dimensional graphene quantum dot layer structure was applied to demonstrate stable operating characteristics based on Li+ ion conductivity and excellent electrochemical performance. Transmission electron microscopy analysis was performed to elucidate the microstructure at the interface. The low-dimensional structure of GQD-based solid electrolytes has provided an important strategy for stable scalable solid-state lithium battery applications at room temperature. This study indicates that the low-dimensional carbon structure of Li-GQDs can be an effective approach for the stabilization of solid-state Li matrix architectures.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.347.2-347.2
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• 2016

Recently, in order to improve the performance of the colloidal quantum dot solar cells (CQDSCs), various efforts such as the modification of the cell architecture and surface treatment for quantum dot (QD) passivation have been made. Especially, the incorporation of halides into the QD matrix was reported to improve the performances significantly via passivating QD trap states that lower the life-time of the minority-carrier. In this work, we fabricated a lead sulfide (PbS) QD bilayer treated with different ligands and utilized it as a photoactive layer of the CQDSCs. The bottom and top PbS layer was treated using metal iodide ($MI_x$ and butanedithiol (BuDT), respectively. All the depositions and ligand treatments were carried out in air using layer-by-layer spin-coating process. The fabrication of the active layers as well as the n-type zinc oxide (ZnO) layer was successfully carried out on the bendable indium-tin-oxide (ITO)-coated polyethylene terephthalate (PET) substrate, which implies that this technique can be applied to the fabrication of flexible and/or wearable solar cells. The power conversion efficiency (PCE) of the CQDSCs with the architecture of $PET/ITO/ZnO/PbS-MI_x/PbS-BuDT/MoO_x/Ag$ reached 4.2 %, which is significantly larger than that of the cells with single QD (PbS-BuDT) layer.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.727-731
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• 1997

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1133-1137
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• 1998

By the mechanical alloying method Ni-W(WC) composite materials were prepared to improve the resistance for creep and sintering of Ni-anode at the operating temperature of$ 650^{\circ}C$. Amorphization was observed from the XRD analysis of mechanically alloyed powder caused by the destruction of ordered crystals. Sintering was performed at $1280^{\circ}C$ for 10 hours in $H_2$ atmosphere. From the result of dot-mapping and TEM analysis the second phase was not observed at Ni-W interface while W particles of less 0.lam were distributed finely and uniformly in Ni matrix. This finely and uniformly distributed W in Ni matrix is expected to enhance the mechanical properties of Ni-anode through the dispersion and solid solution hardening mechanisms.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.4
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• pp.1-12
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• 1979

This article is a sequel to " Korean Character Processing: Part I. Theoretical Foundation " and deals with the practical and historical aspects of the same subject. We discuss , in the first half, the functional design of Korean I/O terminals, Korean character generators based on the conversion algorithm and dot matrix fonts, input keyboard configuration ( trade -offs between a key set and the number of key -strokes ), and the conditions to be considered for binary code design. The second half of the article is devoted to the history of Korean Character processing which is seen from the personal viewpoints. The recorded works are classified into 4 groups according to their maj or contents. Then we bring up each problematic issue to give a critical review of articles . Issues related to output (conversion process) and input ( character recognition) are separated. The bibliography is given in a chronological order.cal order.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2048-2050
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• 2001

기존의 생산관리 현황반, 각종 산업용 판넬의 Faul Indicator, 각종 기계의 상태표시, 엘리베이터 정보출력장치, 주차타워 안내표시, 버스 행선지 안내표시, 병원, 은행 등 각종 광고용에서 사용되는 정보표시장치를 휘도와 안정성이 우수한 40mm 3 Color LED Dot Matrix Module을 이용한 Message 표시장치로서, 각종 Panel 및 기계 장치에 부착되거나 단독 설치되어 Parallel 또는 Serial Port로 입력을 받아 그 입력에 해당되는 Message를 출력 하며 User에 의해 제작되는 Graphic과 Text 형태가 있으며 외부입력에 의해 선택되는 Text Message와 출력 형태는 User에 의해 제작되는 Program에 의해 출력되는 방식으로 구현하여 영문, 숫자는 물론 한글 및 한자 표현도 가능 하도록 하여, 문자의 크기가 5${\times}$7 LED Dot Matrix에 비해 상대적으로 크고 미려하여 현장에서 상황의 인지도를 높이고 ASC-II 및 KS-5601의 Hex Code 입력방식보다 일반사용자가 Programming 하기 쉬우며 Message를 Graphic Symbol형태 및 문자로 작성하여 Message출력 형태를 선택할 수 있는 Mode Programming방식을 적용해 사용자의 용이이성이 배가 되도륵 하여 비교 검토한 결과 사용에 있어 편리성을 입증할 수 있었다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.35-43
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• 1999

We propose and analyze novel optical thyristor which can be used in free-space optical interconnection(FSOI). Novel optical thyristors are fully depleted optical thyristors(DOTs) using bottom mirror and/or multiple quantum wells (MQW), thereby its switching characteristics can be improved significantly. We obtain switching characteristics using coupled junction model associated with current oriented method. Emission characteristics of the DOT are obtained using thin film characteristic matrix and van Roosbroeck-Shockley relation. Compared to the performance using conventional DOT, the optical switching energy is decreased by a factor of 0.43 and the bit-rate is increased by a factor of 1.61 when the DOT with MQW and bottom mirror is employed for FSOI.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.3
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• pp.236-242
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• 2009

When two-link flexible arm is rotated about an joint axis, transverse vibration may occur. In this paper, vibration dynamics of flexible robot arm is modeled by using Bernoulli-Euler beam theory and Lagrange equation. Using the fact that matrix $\dot{D}$-2C is skew symmetric, new controllers which have a simplified structure with less computational burden is proposed. Lyapunov stability theory is applied to achieve a stable deterministic nonlinear controller for the regulation of joint angle.