• 센서학회지
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• 제20권3호
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• pp.145-150
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• 2011

In this paper, we designed a tunable microstrip patch antenna using RF MEMS switches. The design and simulation of the antenna were performed using a high frequency structure simulator(HFSS). The antenna was designed for use in the ISM band and either operates at 2.4 GHz or 5.7 GHz achieving -10 dB return-loss bandwidths of 20 MHz and 180 MHz, respectively. In order to obtain high efficiency and improve the ease of integration, a high resistivity silicon(HRS) wafer on a glass substrate was used for the antenna. The antenna achieved high gains: 8 dB at 5.7 GHz and 1 dB at 2.4 GHz. The RF MEMS DC contact switches were simulated and analyzed using ANSYS software.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.225-245
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• 2008

T-splines are recently proposed mathematical tools for geometric modeling, which are generalizations of B-splines. Local refinement can be performed effectively using T-splines while it is not the case when B-splines or NURBS are used. Using T-splines, patches with unmatched boundaries can be combined easily without special techniques. In the present study, an analysis framework using T-splines is proposed. In this framework, T-splines are used both for description of geometries and for approximation of solution spaces. This analysis framework can be a basis of a CAD/CAE integrated approach. In this approach, CAD models are directly imported as the analysis models without additional finite element modeling. Some numerical examples are presented to illustrate the effectiveness of the current analysis framework.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 가을 학술발표논문집 Vol.28 No.2 (1)
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• pp.286-288
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• 2001

본 논문에서는 기존에 개발된 데이터베이스내의 데이터 소스를 공유하기 위해 통합 라이브러리를 구축하고 이를 통해 데이터베이스내의 소스 데이터에 대한 의미적인 통합을 위한 구조를 제안한다. 데이터의 의미적인 통합을 위해 데이터 스키마가 가지고 있는 실질적인 의미값을 기존의 각 데이터베이스 시스템에서 참조하고 데이터 공유에 대한 동의를 갖도록 메타 데이터를 이용하였다. 따라서 먼저 통합 라이브러리를 구축하여 메타 데이터에 대한 정보와 메타 데이터간에 존재하는 함수적인 관계를 변경 함수로 함께 구현하였으며. 데이터 통합을 위한 참고 자료는 각 시스템마다 온톨로지(Ontology)를 작성하여 활용하였다. 본 논문에서 제안하는 방법은 기존의 방법에 비해 메타데이터의 수정과 주가가 간단하며 새로운 시스템을 통합 라이브러리로 합병하는 비용이 현저히 감소되었다.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4570-4575
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• 2023

Noise and Radio-frequency interference or RFI causes a significant restriction on the Free induction Decay or FID signal detection of the Nuclear Quadrupole Resonance procedure. Therefore, using this method in non-isolated environments such as industry and ports requires extraordinary measures. For this purpose, noise reduction algorithms and increasing signal-to-noise-and-interference ratio or SNIR have been used. In this research, sodium nitrite has been used as a sample and algorithms have been tested in a non-isolated environment. The resonant frequencies for the 150 g of test sample were measured at 303 K at about 1 MHz and 3.4 MHz. The main novelty in this study was, (1) using two types of antennas in the receiver to improve adaptive noise and interference cancellation, (2) using a separate helical antenna in the transmitter to eliminate the duplexer, (3) estimating the noise before sending the pulse to calculate the weighting factors and reduce the noise by adaptive noise cancellation, (3) reject the interference by blanking algorithm, (4) pulse integration in the frequency domain to increase the SNR, and (5) increasing the detection speed by new pulse integration technique. By interference rejection and noise cancellation, the SNIR is improved to 9.24 dB at 1 MHz and to 7.28 dB at 3.4 MHz, and by pulse integration 44.8 dB FID signal amplification is achieved, and the FID signals are detected at 1.057 MHz and 3.402 MHz at room temperature.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1062-1065
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• 2002

We demonstrate the MMIC(monolithic microwave integrated circuit) frequency doublers generating stable and low-cost 29 ㎓ local oscillator signals from 14.5 ㎓ input signals. These devices were designed and fabricated by using the MMIC integration process of 0.1 $\mu\textrm{m}$ gate-length PHEMTs (pseudomorphic high electron mobility transistors). The measurements showed S$\_$11/ of -9.2 dB at 14.5 ㎓, S/sub22/ of -18.6 dB at 29 ㎓ and a minimum conversion loss of 18.2 dB at 14.5 ㎓ with an input power of 6 dBm. The fundamental signal of 14.5㎓ was suppressed below 15.2 dBc compared with the second harmonic signal at the output port, and the isolation characteristics of the fundamental signal between the input and the output port were maintained above 30 dB in the frequency range of 10.5 ㎓ to 18.5 ㎓.

• Earthquakes and Structures
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• 제16권3호
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• pp.359-368
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• 2019

This paper focuses on the study of dynamic analysis of thick plates resting on Winkler foundation. The governing equation is derived from Mindlin's theory. This study is a parametric analysis of the reflections of the thickness / span ratio, the aspect ratio and the boundary conditions on the earthquake excitations are studied. In the analysis, finite element method is used for spatial integration and the Newmark-${\beta}$ method is used for the time integration. While using finite element method, a new element is used. This element is 17-noded and it's formulation is derived from using higher order displacement shape functions. C++ program is used for the analyses. Graphs are presented to help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that the 17-noded finite element is used in the earthquake analysis of thick plates. It is shown that the changes in the aspect ratio are more effective than the changes in the aspect ratio. The center displacements of the reinforced concrete thick clamped plates for b/a=1, and t/a=0.2, and for b/a=2, and t/a=0.2, reached their absolute maximum values of 0.00244 mm at 3.48 s, and of 0.00444 mm at 3.48 s, respectively.

• 대한감각통합치료학회지
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• 제18권3호
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• pp.27-38
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• 2020

목적 : 본 연구는 실행 문제가 있는 일반초등학교에 재학 중인 아동을 대상으로 상호작용식 메트로놈(Interactive Metronome; IM) 훈련을 적용하고, IM 훈련에 따라 타이밍의 변화도를 측정하고자 하였다. 연구방법 : 연구 대상은 만 12세 2개월의 남아 1명이었다. 단일대상연구의 A-B설계를 사용하여 총 11회 기를 적용하였다. 기초선 기간 동안 아동에 대한 IM 전체형 평가, 임상관찰, 단축형 감각프로파일을 실시하였고, 중재 기간 동안 IM 훈련을 하였다. 모든 회기 동안 동일하게 IM의 단축형 평가(Short Form Assessment; SFA) 동작 과제 1, 2를 실시하였고, 변화도를 그림으로 제시하였다. 결과 : 초기평가 결과, 대상 아동은 양측통합과 순서실행장애로 의심되었다. SFA 동작 과제 1, 2에서 기초선 기간에 비해 중재선 기간 동안 타이밍에 대한 정확도가 높았다. 또한 SFA 동작 과제 1의 추세선을 살펴본 결과, 기초선 기간에 음의 기울기를 보였으나 중재기간에는 양의 기울기를 보였다. 결론 : 실행에 문제가 있는 아동의 타이밍에 IM이 긍정적인 효과가 있음을 시사하므로 임상에서 IM 훈련을 적용하는 근거가 될 것으로 보인다.

• 무역학회지
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• 제45권5호
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• pp.141-159
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• 2020

Container terminals at Gwangyang Port are operated by three container operators: A, B and C. Ultimately, there is consensus that a single operator should operate all terminals so that economies of scale can be achieved even in the operation of the container terminal. Integration between operators has a positive effect on both operators and shipping companies. From the operator's point of view, overlapping fixed costs between operators can be unified, reducing overall costs and utilizing spare facilities. On the other hand, from the viewpoint of the shipping company, it is possible to ensure stable use of the port facilities and always allow berthing, reduce days on demurrage and ship waiting, and provide one-stop service for work. However, existing cases of operators' integration or relocation of terminals remained to estimate the expected effects of alternatives, emphasizing only the financial point of view. The port terminal is a large system, and it is important to consider that it is an aggregate of major logistics facilities and equipment. Moreover, if the estimation can be made by quantifying the expected effect, the justification of the terminals' relocation can be further emphasized. Therefore, it is very important to estimate the expected effect from the viewpoint of systemic operation. Moreover, the need for operators' integration can be further emphasized if it can be estimated through quantification of expected effects. Currently, three alternatives are considered as alternatives to the terminals' relocation, and in this study, the optimal plan was derived for the 3 alternatives by the linear planning model of the minimum shuttle transportation cost in the terminal. The optimal plan is alternative 2, which shows the most advantageous integration effect in terms of expected effects. Alternative 2 integrates the B terminal into the C terminal, and the A terminal operates independently as it is.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1673-1675
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• 2004

The design, modeling and measurement of RF switch module for GSM applications is presented in this paper. RF switch module is constructed using a LTCC multi-layer switching circuit and integrated low pass filter. Insertion and return loss of the low pass filter were designed less than 0.3 dB and better than 12.7 dB at 900 MHz. The RF switch module contained 10 embedded passives and 3 surface mount components integrated on $4.6{\times}4.8{\times}1.2$ mm, 6-layer multi-layer integrated circuit. The insertion loss of switch module was measured at 900 MHz was 11 dB.

• 인터넷정보학회논문지
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• 제3권5호
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• pp.1-8
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• 2002

XML은 표준화와 운영체제 중립적이라는 특성 때문에 전자상거래에서 중요한 위치를 차지하며, 이미 많은 전자상거래 시스템에서 이용하고 있다. B2B 전자상거래분야를 위해서는 기업간 비즈니스에 대한 업무 규칙과 절차가 표준화되어야 한다. 그러나 기업들이 표준화 된 XML 문서를 사용하는 것이 아니라 기업의 실정에 맞게 시스템을 구축하여 기업간 XML 문서 전달을 하고 있어, 이에 따라 많은 문제점이 나타나고 있다. 이러한 요구를 기반으로 많은 조직과 기업에서는 XML을 기반으로 하는 전자상거래 표준화 작업을 프레임워크 형태로 진행하고 있다. 또한 공급사슬관리 시스템에서 기업간의 문서 전달을 온라인을 이용하기 때문에 XML 메시지를 전송 할 수 있는 메시징 시스템이 필요하다. 본 논문에서는 XML로 서비스를 요청하고 서버가 해당 서비스를 처리하는, XML 메시징 시스템을 설계 및 구현하였다. 본 메시징 시스템을 이용하여 기업간의 문서를 교환하는데 좀더 효율적으로 이용할 수 있을 것이다.