• 대한전자공학회논문지TC
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• 제47권9호
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• pp.1-8
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• 2010

DPM (Digital Phase wrapping Modulation) open-loop polar transmitter는 in-phase와 quadrature 신호를 진폭(envelope) 신호와 위상(phase) 신호로 변환한 후 신호의 사상화 과정을 거쳐 광대역 통신 시스템에서의 효율적인 적용이 가능하다. 사상화 과정은 일반적인 통신 시스템에서의 양자화와 유사하며 그 과정에서 발생하는 오차를 고려할 때 좌표계 변환부에 CORDIC (COordinates Rotation DIgital Computer) 알고리듬 대신 테일러 급수 근사 기법의 사용이 가능하다. 본 논문에서는 테일러 급수 근사 기법을 광대역 OFDM (Orthogonal Frequency Division Multiplexing) 시스템용 DPM polar transmitter의 직교 좌표계-극 좌표계(cartesian to polar coordinate) 변환부에 적용하는 방안에 대한 연구를 수행하였다. 기존의 방법은 CORDIC 알고리듬을 채용하고 있다. 이것을 효율적으로 적용하기 위해 모의 실험을 통해 각각의 기법에 대한 평균제곱오차 (MSE : Mean Square Error) 성능을 측정하고, 설계 관점에서 허용된 CORDIC 오차를 기준으로 알고리듬의 최소 반복횟수와 테일러 급수의 최소 근사 차수를 찾는다. 또한 FPGA 전달 지연속도를 비교한 결과에 의하면 CORDIC 알고리듬 대신 낮은 차수의 테일러 급수 근사 기법을 사용해 좌표 변환부의 처리 속도를 향상시킬 수 있음을 확인하였다.

• 대한전자공학회논문지TC
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• 제44권2호
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• pp.22-28
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• 2007

높은 PAPR (peak-to-average power ratio)은 OFDM (orthogonal frequency division multiplexing) 신호의 주된 문제점이다. 본 논문에서는 RS (Reed-Solomon) 부호의 소실 복호 기능을 이용한 수정된 SLM (selective mapping) 기법을 제안한다. 송신기에서 RS 부호화된 OFDM 데이터 블록에 일련의 위상 시퀀스를 곱하여 일부의 체크 심볼의 위상을 천이시킨다. 수신기에서 위상 천이된 체크 심볼들을 소실로 간주하여 RS 복호를 수행한다. 그러므로 가장 낮은 PAPR을 갖도록 선택된 위상 시퀀스에 대한 부가 정보를 전송할 필요가 없다. 또한 선택된 위상 시퀀스에 대한 추정 과정이 더 이상 수신기에 필요하지 않게 되어 복잡도와 성능이 향상된다. 제안한 수정된 SLM 기법의 성능을 평가하기 위해 PAPR의 CCDF(complementary cumulative distribution function), BER(bit error rate) 그리고 복호 실패 확률을 기존의 SLM 기법과 비교한다.

• 경영과학
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• 제15권2호
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• pp.109-124
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• 1998

Recently, as the importance placed on the design phase of system development has increased, the use of diagrams to design the overall system before implementing the actual program code has seen a proportionate increase. This study focuses on the diverse diagrams depicting organizational processes when integrating multiple processes of individual organizations to form an Inter-Organizational System(IOS). In this study, we attempt to identify the critical representation features of process diagrams that enable the effective integration of Inter-Organizational processes. In particular, the effect of the mapping relationship between the representation features of different diagrams to be integrated was tested empirically in a laboratory setting. The experimental task consisted of integrating the processes of two organization based upon the given process diagrams. Actual business processes were selected from real world cases and process diagrams were formulated based upon existing object-oriented notation. An analysis of the errors committed by the subjects during the integration process indicated that the mapping relationship between the diagram features representing the respective organizational processes had a significant impact upon the final integration outcome. Based upon these results, the present study provides a guideline for process diagrams that are crucial to effective Inter-Organizational process implementation and maintenance.

• 한국초등과학교육학회지:초등과학교육
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• 제34권4호
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• pp.419-433
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• 2015

Analogical reasoning is a central component of human cognition and contributes to scientific discovery and to develop science education. In this study, we investigated the process features of lower elementary school students' analogical reasoning to explain mixture concept. The subjects are 24 lower elementary students. And the research design includes three phases instruction to investigate the features of students' self generated analogy. Phase 1 is the introduction of analogy in which student learn to use analogy. Phase 2 is a POE class about mixture conception. Piaget and Inhelder studied the conception of mixing among children in relation to cognitive development. In phase 2, we taught the student with Piaget and Inhelder's the experiment and observed the features of learning process about mixture conception. Phase 3 is students' generation of analogy (self generated analogy) for the experienced phenomena in phase 2. We analyzed the students' responses through the three phases in the view of Gentner's Structure Mapping Theory. The results showed that many lower elementary school students even before formal operation stage understood the mixture conception and made well their self generated analogy to explain the mixture conception in spite of the difficulty of making self generated analogy.

• 한국세라믹학회지
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• 제36권10호
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• pp.1075-1079
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• 1999

LaSrCoO3 thin films were spin-coated onto the SrTiO3(100) substrates by the chemical solution process. X-ray diffraction $\theta$-2$\theta$ scans and X-ray diffraction $\beta$ scans were used to determine the crystallinity and in -plane alignment behavior of the films. The X-ray diffraction pattern showed the film obtained by annealing at 80$0^{\circ}C$ was highly oriented. The X-ray diffraction pole-figure analysis and reciprocal-space mapping (2$\theta$-$\Delta$$\omega$ scans) of the resulting film showed that the film comprising the pseduocubic phase had an epitaxial relationship with the SriO3 substrate.

• Smart Structures and Systems
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• 제22권2호
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• pp.201-207
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• 2018

This paper proposes a line laser thermography scanning (LLTS) system for multiple crack evaluation on a concrete structure, as the core technology for unmanned aerial vehicle-mounted crack inspection. The LLTS system consists of a line shape continuous-wave laser source, an infrared (IR) camera, a control computer and a scanning jig. The line laser generates thermal waves on a target concrete structure, and the IR camera simultaneously measures the corresponding thermal responses. By spatially scanning the LLTS system along a target concrete structure, multiple cracks even in a large scale concrete structure can be effectively visualized and evaluated. Since raw IR data obtained by scanning the LLTS system, however, includes timely- and spatially-varying IR images due to the limited field of view (FOV) of the LLTS system, a novel time-spatial-integrated (TSI) coordinate transform algorithm is developed for precise crack evaluation in a static condition. The proposed system has the following technical advantages: (1) the thermal wave propagation is effectively induced on a concrete structure with low thermal conductivity of approximately 0.8 W/m K; (2) the limited FOV issues can be solved by the TSI coordinate transform; and (3) multiple cracks are able to be visualized and evaluated by normalizing the responses based on phase mapping and spatial derivative processes. The proposed LLTS system is experimentally validated using a concrete specimen with various cracks. The experimental results reveal that the LLTS system successfully visualizes and evaluates multiple cracks without false alarms.

• 대한안전경영과학회지
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• 제13권2호
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• pp.231-241
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• 2011

Business processes are often of long duration, and include internal worker's decision making, which makes business processes to be exposed to many exceptional situations. These properties of business processes makes it difficult to guarantee successful termination of business processes at the design phase. The behavioral properties of business processes mainly depends on the data aspects of business processes. To formalize the data aspect of process modeling, this paper proposes a graph-based model, called Data Dependency Graph (DDG), constructed from dependency relationships specified between business data. The paper also defines a mechanism of describing a set of mapping rules that generates a process model semantically equivalent to a DDG, which is accomplished by allocating data dependencies to component activities.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.460-464
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• 2002

Multitemporal interferometric SAR has became an useful geodetic tool for monitoring Earth's surface deformation, generation of precise DEM, and land cover classification even though there still exist certain constraints such as temporal and spatial decorrelation effects, atmospheric artifacts and inaccurate orbit information. The Korea where nearly all areas are heavily vegetated, JERS-1 SAR has advantages in monitoring surface deformations and environmental changes in that it uses 4-times longer wavelength than ERS-l/2 or RADARSAT SAR system. For generating differential SAR interferogram and differential coherence image fer deformation mapping and temporal change detection, respectively, topographic phase removal process is required utilizing a reference inteferogram or external DEM simulation. Because the SAR antenna baseline parameter for JERS-1 is less accurate than those of ERS-l/2, one can not estimate topographic phases from an external DEM and the residual phase appears in differential interferogram. In this paper, we examined topographic phase retrieval method utilizing an external DEM. The baseline refinement is carried out by minimizing the differences between the measured unwrapped phase and the reference points of the DEM.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1089-1093
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• 2005

Proving the effect of lean construction has yet to be done for its staying poor basic building though there has been efforts and wants to introduce the theory and concept of lean construction in practical site. Therefore, we need to specify the methods of productivity improvement and construction process through various adaptations in the site. Also, to apply such improvement methods systematically, we need active participation of owners, contractors and supply chain members in relation to construction industry and are also require appropriate methods to adapt. At first, this study thinks over the techniques of lean construction that has been verified through studies carried before. For second, it selects the technique of lean construction with the practicality in the construction site. For third, it is aimed to make a manual of lean process management by the use of TACT and V.S.M. For fifth, it will show the method of management for repeated activity and develop a guide-line and procedure that applies the concept of work sequence and resource equalization to each phase of process management. At last, it will show methods of reflecting V.S.M. to improve and grasp the waste factor from the step of managing an activity process and develop the form to analyze the waste in construction site by mapping the value flow.

• The Korean Journal of Ceramics
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• 제3권4호
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• pp.253-256
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• 1997

Epitaxially grown Pb(Zr, Ti)O$_3$thin films were prepared on LaAlO$_3$substrates by the dipping pyrolysis process using metal naphthenates as starting materials Homogeneous Pb-Zr-Ti solutions with toluene were spin-coated onto the substrates and pyrolyzed at 50$0^{\circ}C$ Highly oriented Pb(Zr, Ti)O$_3$films confirmed by X-ray diffraction $\theta$-2$\theta$ scans were obtained by heat-treated at 75$0^{\circ}C$ in air The X-ray pole-figure analysis and reciprocal-space mapping of the resulting 0.6$\mu\textrm{m}$ films showed that the thin films comprising the c-axis oriented tetragonal phase have an epitaxial relationship with the LaAlO$_3$substrates.