• 제목/요약/키워드: Sub System

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High Spatial Resolution Imaging of the Contiguous Objects Using Sub-Y-Type Interferometric Synthetic Aperture Radiometer

  • Lee Ho-Jin;Park Hyuk;Kim Sung-Hyun;Choi Jun-Ho;Seo Seung-Won;Kim Yong-Hoon;Kang Gum-Sil
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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    • pp.53-56
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    • 2004
  • Recently the interferometric synthetic aperture radiometer with sub-Y-type antenna array was suggested to improve the spatial resolution than that of conventional Y-type with the same number of antenna elements. The sub-Y-type performance has been reported under a point source target. In this paper, the performance of sub-Y-type is evaluated under contiguous objects. The angular resolution of sub-Y-type with 52 antennas was compared with that of Y-type with the 40 antennas. The images of sub-Y -type and Y-type array were simulated under the contiguous objects. The sub-Y-type showed higher resolution than Y-type in the simulation and experiments. The sub-Y-type has high spatial resolution than Y-type in case of contiguous source as well as single point source.

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ON A THREE-DIMENSIONAL SYSTEM OF DIFFERENCE EQUATIONS WITH VARIABLE COEFFICIENTS

  • KARA, MERVE;YAZLIK, YASIN;TOUAFEK, NOURESSADAT;AKROUR, YOUSSOUF
    • Journal of applied mathematics & informatics
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    • 제39권3_4호
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    • pp.381-403
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    • 2021
  • Consider the three-dimensional system of difference equations $x_{n+1}=\frac{{\prod_{j=0}^{k}}z_n-3j}{{\prod_{j=1}^{k}}x_n-(3j-1)\;\(a_n+b_n{\prod_{j=0}^{k}}z_n-3j\)}$, $y_{n+1}=\frac{{\prod_{j=0}^{k}}x_n-3j}{{\prod_{j=1}^{k}}y_n-(3j-1)\;\(c_n+d_n{\prod_{j=0}^{k}}x_n-3j\)}$, $z_{n+1}=\frac{{\prod_{j=0}^{k}}y_n-3j}{{\prod_{j=1}^{k}}z_n-(3j-1)\;\(e_n+f_n{\prod_{j=0}^{k}}y_n-3j\)}$, n ∈ ℕ0, where k ∈ ℕ0, the sequences $(a_n)_{n{\in}{\mathbb{N}}_0$, $(b_n)_{n{\in}{\mathbb{N}}_0$, $(c_n)_{n{\in}{\mathbb{N}}_0$, $(d_n)_{n{\in}{\mathbb{N}}_0$, $(e_n)_{n{\in}{\mathbb{N}}_0$, $(f_n)_{n{\in}{\mathbb{N}}_0$ and the initial values x-3k, x-3k+1, …, x0, y-3k, y-3k+1, …, y0, z-3k, z-3k+1, …, z0 are real numbers. In this work, we give explicit formulas for the well defined solutions of the above system. Also, the forbidden set of solution of the system is found. For the constant case, a result on the existence of periodic solutions is provided and the asymptotic behavior of the solutions is investigated in detail.

지연 민감형 IoT 응용을 위한 GQS 기반 포그 Pub/Sub 시스템의 설계 및 평가 (Drsign and Evaluation of a GQS-based Fog Pub/Sub System for Delay-Sensitive IoT Applications)

  • 배인한
    • 한국멀티미디어학회논문지
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    • 제20권8호
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    • pp.1369-1378
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    • 2017
  • Pub/Sub (Publish/Subscribe) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. In general, subscribers register their interests in a topic or a pattern of events and then asynchronously receive events matching their interest, regardless of the events' publisher. In order to build a low latency lightweight pub/sub system for Internet of Things (IoT) services, we propose a GQSFPS (Group Quorum System-based Fog Pub/Sub) system that is a core component in the event-driven service oriented architecture framework for IoT services. The GQSFPS organizes multiple installed pub/sub brokers in the fog servers into a group quorum based P2P (peer-to-peer) topology for the efficient searching and the low latency accessing of events. Therefore, the events of IoT are cached on the basis of group quorum, and the delay-sensitive IoT applications of edge devices can effectively access the cached events from group quorum fog servers in low latency. The performance of the proposed GQSFPS is evaluated through an analytical model, and is compared to the GQPS (grid quorum-based pud/sub system).

H2/H 설계사양을 만족하는 선박운동제어계 설계에 관한 연구 (Control System Design for Marine Vessel Satisfying Mixed H2/H Performance Condition)

  • 강창남;김영복
    • 제어로봇시스템학회논문지
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    • 제19권9호
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    • pp.846-852
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    • 2013
  • In this paper, the authors propose a new approach to control problem of the marine vessels which are moored or controlled by actuators. The vessel control problem in the specified area is called a DPS (Dynamic Positioning System). The main objective of this paper is to obtain more useful control design method for DPS. In this problem, a complicate fact is control allocation which is a numerical method for distributing the control signal to the controlled system. For this, many results have been given and verified by other researchers using two individual processes. It means that the controller design and control allocation design process are carried out individually. In this paper, the authors give more sophisticated design solution on this issue. In which the controller design and control allocation problem are unified by a robust controller design problem. In other word, the stability of the closed-loop system, control performance and allocation problem are unified by an LMI (Linear Matrix Inequality) constraint based on $H_2/H_{\infty}$ mixed design framework. The usefulness of proposed approach is verified by simulation with a supply vessel model and found works well.

SnO2-TiO2-V2O5계의 노랑안료 합성 (Synthesis of SnO2-TiO2-V2O5 System Yellow Pigment)

  • 주인돈;황동하;이현수;박주석;이병하
    • 한국세라믹학회지
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    • 제46권6호
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    • pp.639-642
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    • 2009
  • The research was performed to find out the optimum firing condition for the $SnO_2-TiO_2-V_2O_5$ system yellow pigment. The pigment based on $SnO_2-V_2O_5$ system showed very intense yellow color and it was used widely in ceramics industry. Synthesized pigment, with partial substitutions of $SnO_2\;by\;TiO_2$, was fired at $1300{^{\circ}C}$ soaking 1h and it showed bright yellow color. $SnO_2-TiO_2-V_2O_5$ system was very more intensive changes in yellow color by colorimetric value $b^*$ than $SnO_2-V_2O_5$ system. Synthesized yellow pigments were characterized by X-ray diffraction (XRD), FT-IR, and UV-vis spectroscopy. The best composition for yellow pigment was 93:7:0.5(mole%) for $SnO_2-V_2O_5-TiO_2$. The measurement of CIE $L^*a^*b^*$ of pigment was $L^*(78.82),\;a^*(-4.88)\;and\;b^*$(59.25).

연속흐름식 반응기를 이용한 TiO2/H2O2/UV에 의한 클로로페놀 제거(除去)에 관한 실험적(實驗的) 연구(硏究) (An Experimental Study on the Removal of Chlorophenol by TiO2/H2O2/UV Using Continuous flow Reactor)

  • 이상협;박주석;박중현;김동하
    • 상하수도학회지
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    • 제12권3호
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    • pp.55-64
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    • 1998
  • The degradation efficiency of chlorophenolic compounds in $TiO_2/H_2O_2$ combined system was compared with that of in $TiO_2$ sole system. As a result, the addition of hydrogen peroxide in photocatalytic oxidation reaction greatly enhanced the degradation efficiency of chlorophenolic compounds due to the availability of the hydroxyl radical formed on the $TiO_2$ surface. The hydrogen peroxide under UV illumination produces hydroxyl radicals that appear to be another source of hydroxyl radical formation. These results indicated the $TiO_2/H_2O_2$ combined system shows higher degradation efficiency than the $TiO_2$ sole system. Compared to another oxidation reaction, hydrogen peroxide assisted photocatalytic oxidation is more promising in practical aspect.

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H2O/LiBr+HO(CH2)3OH계 공냉형 이중효용 흡수식 냉방시스템의 사이클 해석 (Cycle Analysis of Air-Cooled Double-Effect Absorption Cooling System Using H2O/LiBr+HO(CH2)3OH)

  • 권오경;문춘근;윤정인
    • 대한기계학회논문집B
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    • 제23권2호
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    • pp.272-280
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    • 1999
  • A cycle analysis was achieved to predict the characteristics by comprehensive modeling and simulation of an air-cooled, double-effect absorption system using a new $H_2O/LiBr+HO(CH_2)_3OH$ solution. The simulation results showed that the new working fluid may provide the crystallization limit 8% higher than the conventional $H_2O/LiBr$ solution. With a crystallization margin of 3wt%(weight%), the optimal solution distribution ratio was found in the range of 36 to 40%. Variation of cooling air Inlet temperature has a sensitive effect on the cooling COP and corrosion problem. The simulation of heat exchangers with UA value revealed that the absorber and the evaporator are relatively important for an air-cooled system compared with the condenser and the low temperature generator. The effect of cooling air flow rate, circulation weak solution flow rate and chilled water inlet temperature were also examined. The new working fluid may provide the COP approximately 5% higher than the conventional $H_2O/LiBr$ solution.

Bi2Te3계 열전박막의 열전 출력인자에 미치는 첨가제의 영향 (Doping Effects to the Thermoelectric Power Factor of Bi2Te3 Thin Films)

  • 배상현;최순목
    • 한국전기전자재료학회논문지
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    • 제33권2호
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    • pp.141-146
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    • 2020
  • Thermoelectric Bi2Te3 thin films were synthesized by a co-sputtering method at 300℃. A Fe dopant was considered to enhance the thermoelectric properties of the system. The Seebeck coefficient of the Fe-doped films increased whereas the electrical conductivity decreased. As a result, the power factor of the system increased owing to the enhanced Seebeck coefficient. Grain growth inhibition was detected in the Fe-doped system, which produced more grain boundaries in the Fe-doped films than in the undoped system. The increased grain boundary scattering was deemed to be effective for a reduced thermal conductivity. This is advantageous for the preparation of high-performance thermoelectric films.

단위전지 제작을 통한 BaCe0.9M0.1O3−δ (M=La, Al)계 Proton 전도성 산화물 전해질의 특성평가 (Single Cell Test for Proton Conducting Oxide Electrolytes Based on the BaCe0.9M0.1O3−δ (M=La, Al) System)

  • 최순목;정성민;서원선;이홍림
    • 한국세라믹학회지
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    • 제45권11호
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    • pp.694-700
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    • 2008
  • Proton conducting oxides based on the $BaCe_{0.9}M_{0.1}O_{3-{\delta}}$ (M = La, AL) were tested for the alternative electrolyte materials of fuel cell. The power density for single cell of Air |Pt| $BaCe_{0.9}M_{0.1}O_{3-{\delta}}$ |Pt| $H_2(3%H_2O)$ system was maximum $0.04W/cm^2$ at $1000^{\circ}C$. In this system, proton transport number was proved to depend on the lattice parameters and the distortion of $CeO_6$ octahedral as a function of the ionic radii of acceptor ions. This proton conducting oxide system requires developing the new electrode materials for application.

Fe 도핑된 TiO2와 헥사데실트리메톡시실란를 이용한 셀프클리닝 섬유의 제조 및 평가 (Preparation and Evaluation of Self-cleaning Fabrics using Fe-doped TiO2 and Hexadecyltrimethoxysilane)

  • 문예진;조승빈;정의경;배진석
    • 한국염색가공학회지
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    • 제32권3호
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    • pp.158-166
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    • 2020
  • Self-cleaning fabric is a fabric having a function of decotamination via photodecomposition of photocatalyst or wash-off of contaminants on the superhydrophobic surface. TiO2 is the main photocatalyst for this purpose, but it only functions under UV light which is only a little portion of sunlight, compared to visible light. In this regard, this study aims to investigate Fe-doped TiO2 for improved photodecomposition from visible light sensitization to apply self-cleaning finishing of PET fabrics. Moreover, the Fe-doped TiO2 treated PET fabric was further treated with hexadecyltrimethoxysilane to provide superhydrophobicity on the PET fabrics. As a result of this dual treatment, the prepared fabric exhibited excellent photodecomposition of methylene blue with 96.96% in 12h under sunlight and superhydrophobicity with water contact angle of 166.5° and roll-off angle of 7°. This suggested that the excellent self-cleaning functions can be privided to PET fabric via Fe-doped TiO2 and hexadecyltrimethoxysilane treatment.