• 전기학회논문지
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• 제58권5호
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• pp.1035-1040
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• 2009

We propose a new encoder/decoders based on an tune able wavelength converter(TWC) and an arrayed waveguide grating(AWG) router for large capacity optical CDMA networks. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

• 한국콘텐츠학회논문지
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• 제3권2호
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• pp.87-95
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• 2003

연구개발에 있어서 각 연구 분야와 관련된 신속하고 적절한 정보의 획득은 산업사회의 국가 기술 경쟁력을 좌우하는 중요한 요소로 대두되고 있다. 따라서 연구개발활동을 지원하기 위한 도구로써 다양한 형태의 전문 데이터베이스의 구축 및 효율적인 운영을 통한 적합 정보의 제공은 연구생산성 제고에 있어 필연적인 과제라 할 수 있다. 본 연구에서는 산$.$학$.$연 과학자들의 연구 활동을 지원하고 촉진시키기 위한 세라믹 재료 물성 데이터베이스를 개발하였다. 데이터베이스는 과학자 및 연구개발자들에 대한 수요조사를 통해 가장 중요하다고 응답한 재료분야의 세라믹 물성 데이터베이스를 선정하였으며, 데이터베이스 개발을 위해서는 세라믹 재료물성 정보의 항목과 구조를 분석하여 국내 이용자들에게 적합하도록 데이터베이스 설계를 수행하였다. 본 연구 결과를 활용함으로써 연구 개발자들이 물성정보 획득을 위해 투여되는 시간과 비용을 크게 줄일 수 있으며, 연구생산성이 크게 향상될 것으로 기대된다.

• 한국통신학회논문지
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• 제21권9호
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• pp.2470-2480
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• 1996

The energy efficiency and bandwidth efficiency are two important criterion in designing a modulation scheme Especially the constant envelope property must be considered as in the non-linear channel tht exit, for example in the nonlinear amplifiers for satellite repeater. The Q$^{2}$AM(Quadrature Quadrature Amplitude Modulation) is a new modulation scheme which combines the Q$^{2}$PSK(Quadrature Quadrature Phase Shift Keying) scheme which increases the signal space dimension and the QAM scheme which increases the bandwidth efficiency using the multi-level signal. The Q$^{2}$AM scheme has by far superior spectrum efficiency compared with the existing modulation schemes. Applying this scheme in the non-linear communication system increses the bandwidth efficiency but cannot envelop property. In this paper, a new system architecture is suggested which satisfies the large spectrum efficiency and constant envelope property by implementing the linear block coding prior to the Q$^{2}$AM modulation. the system has improved in performance by gaining the constant envelope and the additional coding gain. We able to observe the performance improvement of the suggested system(at BER=10$^{-5}$ ) of 4.4 dB for the 16-QAM and 0.7 dB for the Q$^{2}$PSK under the exact spectrum efficiency.

• 한국통신학회논문지
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• 제23권5호
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• pp.1165-1172
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• 1998

본 논문에서는 다항식 $z^{d}+(z+1)^{d}$를 이용하여 이상적인 자기상관특성을 갖는 주기 $2^{m}-1$의 이진 의사불규칙시퀀스를 구성하는 것을 보였다. 다항식으로부터 얻어진 시퀀스는 어떤 d값에서는 m-시퀀스가된다. 또한 k가 양의 정수이고 m이 $3k{\pm}1$일 때 이상적인 자기상관특성을 갖는 새로운 이진 시퀀스를 산출하는 몇몇의 d값을 발견했다. 이들 새로운 시퀀스는 trace함수를 이용하여 표현하였으며 그 결과들을 표로 나타내었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1487-1489
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• 2001

The tantalum oxide($Ta_2O_5$) is an important material for present thin-film capacitor application owing to its high dielectric constant and thermal stability. We report dielectric property of Si(p type)/Pt/$Ta_2O_5$/Ag based MIM structure obtained by RF sputtering and annealed in vacuum environment. We have measured and researched the characteristics of C-F, C-V and EPMA. And we describe parameter dependence on sputtered condition and annealed temperature with dielectric property.

• 한국환경과학회지
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• 제21권4호
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• pp.471-478
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• 2012

In this study, the flow characteristic analysis at the curved-channel of the actual channel section is compared and reviewed using the 2D RMA-2 model and the 3D FLOW-3D model. the curve section with curve rate 1.044 in the research section is analyzed applying the frequency of he project flood of 100 years. According to the result, the issue for the application of the FLOW-3D Model's three-dimensional numeric analysis result to the actual river is found to be reviewed with caution. Also, application of the 3D model to the wide basin's flood characteristic is determined to be somewhat risky. But, the applicability to the hydraulic property analysis of a partial channel section and the impact analysis and forecast of hydraulic structure is presumed to be high. In addition, if the parameters to reflect the vegetation of basin and the actual channel, more accurate topological measurement data and the topological data with high closeness to the current status are provided, the result with higher reliability is considered to be drawn.

• International Journal of Concrete Structures and Materials
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• 제18권3E호
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• pp.165-171
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• 2006

Environment-friendly materials are increasingly used as building construction materials nowadays, and the market share of those is growing. Accordingly, the research and developments in terms of environmental value are progressing steadily now. The main characteristics of environmental products are far-infrared radiation, negative-ion emission, electromagnetic wave shielding, and antimicrobial property. These products are often used in mortar and as spray on the finishing material. Nevertheless, there are hardly any research on the functional properties of concrete, the main material in construction field. Thus, we evaluated such basic properties of concrete as slump, compressive strength and air content while using such functional materials as sericite, wood-pattern sandstone, carbon black and nano-metric silver solution to focus on their functional properties like far-infrared radiation, negative ion emission, electro magnetic wave shielding, and antimicrobial activity in this research. The results indicated that the most useful material in the functional materials was carbon black. Sericite and nano-metric silver solution had a little effect on the functional property. Moreover, although wood-pattern sandstone had very high functional property, it exhibited too low compressive strength to be applied, to concrete as a factory product. Antimicrobial property of nano-metric silver solution in the concrete was not clear demonstrated, but if these specimens were to be aged in $CO_2$ gas for a long time, it might be apparent.

• 한국응용과학기술학회지
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• 제28권3호
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• pp.359-366
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• 2011

In this study we experimented that how polyurethane effect to acrylic-polyurethane resin in Full-Grain leather coatings. First of all, we consummated waterborne acrylic emulsion and waterborne polyurethane resin, Than we prepared F.G leathers which were coated by acrylic resin and acrylic-polyurethane resins. According to measured data for solvent resistance, acrylic resin and acrylic-polyurethane resins had good property. Sample a(WAC) had most low strength($2.10kg_f/mm^2$) and sample d(WAC 93 : WPU 7) had most high strength($3.41kg_f/mm^2$). Also we knew that most good property of abrasion is d(47.4 mg). In elongation case, a(WAC) had most good result(645 %) in this experiment.

• 한국전기전자재료학회논문지
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• 제37권5호
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• pp.476-485
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• 2024

Understanding the structure-property relationship in functional materials is crucial as microstructural features such as nano-precipitates, phase boundary, grain boundary segregation, and grain boundary phases play a key role in their functional properties. Atom probe tomography (APT) is an advanced analytical technique that allows for the three-dimensional (3D) mapping of atomic distributions and the precise determination of local chemical compositions in materials. Moreover, it offers sub-nanometer spatial resolution and chemical sensitivity at the tens of parts per million (ppm) level. Owing to its unique capabilities, this technique has been employed to uncover the 3D elemental distributions in a wide range of materials, including alloys, semiconductors, nanomaterials, and even biomaterials. In this paper, various kinds of examples are introduced for elucidating structure-property relationships on functional materials by utilizing the atom probe tomography.

• 대한화장품학회지
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• 제22권2호
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• pp.167-173
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• 1996

The stability of gel structured emulsion and the effect of polyols on it have been studied by rheological property and interfacial tension. In this paper, three types of gel structured emulsions were prepared by using three polyols respectively(glycerine for sample 1, 1.3 BG for sample 2, PG for sample 3). And both complex modulus($G^*$) and loss angle[$\delta$ = tan-1(G"/G')] of samples were investigated against oscillating shear stress and frequency($\omega$). The results show sample 1 is most highly consistent with oscillating shear stress. And the results were compared with those of accelerated tests concerning storage stability of gel structured emulsion. To correlate consistency of rheological property with storage stability, interfacial tension from which adsorption efficiency of surfactant(Octyldodecyl Ether) could be known was measured. Sample 1 showed the largest value of [$d{\gamma}/dIn_{Cconc. of surfactant}$] in Gibbs equation. In summary, the prediction of stability could be correctly made by the consistency of rheological property(G*,$\gamma$) of gel structured emulsion against oscillating shear stress and it could be supported by measuring interfacial tension. And polyol affected the value of [$d{\gamma}/dIn_{Cconc. of surfactant}$], consequently affected the stability.lity.