• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.2
• /
• pp.143-151
• /
• 2010

In this paper, a novel rectangular patch antenna is proposed to have Zeroth Order Resonance(ZOR) generated based on the Metamaterial Complosite Right- and Left-Handed(CRLH) structure. Making the in-phase electric field over the entire antenna other than a half-wavelength as the fundamental resonance mode of a standard microstrip patch or its positive multiple, the metallic patch is suggested to be capacitively coupled with only one surrounding rectangular ring, different from the previous 1D ZOR antennas commonly having several metal cells in line. The performance of the proposed antenna is simulated by a 3D field solver that inputs the sizes of the physical structure corresponding to the equivalent circuit designed to have ZOR at 2.4 GHz. Consequently, the resonance frequency, the gain and the antenna efficiency are observed 2.4 GHz, 5 dB and 98%, respectively. Besides, the important property of the proposed antenna is addressed as the combination of the low profile as an advantage of microstrip patch antennas, and the omni-directional field pattern typical of monopole antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.5
• /
• pp.727-737
• /
• 1999

Printed microstrip antennas are known to have limitations in terms of bandwidth and efficiency all imposed by the presence of the dielectric substrate. In this paper, to overcome these limitations, rather than using a superstrate geometry, the printed circuit is etched out of metal and supported in "strategic points" by(metallic or nonmetallic) post. The main motivation for this work was to obtain the wide bandwidth microstrip antennal which exhibits a higher efficiency than conventional ones. In this paper, to increase the bandwidth, patch sizes, electrical thickness and impedance matching are considered.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.86.2-86.2
• /
• 2012

산화금속은 높은 결정성, quantum size effect, 높은 투과도, 대기중의 안정도 등과 같은 탁월한 성질들로 인하여 오늘날 실리콘의 대체물로서 많은 연구가 보고되고 있다. 이러한 금속산화물의 크기와 모양을 조절하며 대량 생산하기 위한 합성방법으로 가수분해, 금속양이온 응축법과 같은 다양한 수용액상 방법이 연구되고 있다. 하지만 2차원 단일 층에 나노물질을 정렬하고 전기적 접합을 형성하는 것이 매우 어렵다는 점 때문에 나노물질을 기판 위에 자유롭게 성장시키는 방법에 대해서는 아직 많이 보고 되어있지 않다. 본 연구에서 저온의 수용액에서 1차원의 나노막대가 2차원의 스피넬 구조 위에 heteroepotaxial 접합을 이루며 성장시키는 방법을 이용하였다. P-n접합 형성을 위하여 (0001)방향으로 배향된 n-type ZnO 나노막대를 (111)방향의 p-type Co3O4 나노플레이트 위에 성장시킨 구조를 제작하였으며 이를 바탕으로 다이오드소자를 제작하여 ideal factor, turn-on voltage, rectifying ratio등의 전기적 특성을 평가하였다.

• Proceedings of the Korea Contents Association Conference
• /
• 2013.05a
• /
• pp.31-32
• /
• 2013

밀리미터 대역에서 고출력 신호를 장거리로 전송하기 위해서는 안테나 이득을 증가시켜야 한다. 이를 위해 사용되는 방법 중 하나가 금속 개구면 격자배열을 구조를 이용하여 안테나를 설계하는 것이다. 이러한 반사배열 안테나는 격자구조의 기하학적 패턴이 개구효율에 큰 영향을 미친다. 본 논문에서는 개구효율을 향상시키기 위한 최적의 기하학적 패턴을 찾기 위한 방법으로 유전알고리즘 기법을 제안한다. 유전 알고리즘 기법을 적용한 모의실험 결과는 제안한 방법이 개구효율을 향상시키는데 도움이 된다는 것을 보여주었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.456-457
• /
• 2007

ATCB의 구조 중 아크 소호부는 공기 중에 노출된 금속(그리드)이 일정한 간격을 두고 적층되어 있는 모양을 하고 있다. 아크 소호부의 주기능은 아크를 소호실 안쪽으로 유도하여(기중 차단방식) 여러 개의 짧은 아크로 분할시키며 아크를 냉각, 소멸시켜 전류 차단을 빠르게 하는 것이다. 아크를 구동시키는 소호살의 형상과 구조에 따라 아크의 구동력은 많은 차이를 보이게 된다. 여기서는 신개념의 자동절체 스위치인 ATCB(Automatic Transfer Circuit Breaker)의 그리드의 구조에 따라 아크 구동력을 비교하여 아크 소호부의 최적 형상과 절연구조를 설계, 모델링하였다.

• Explosives and Blasting
• /
• v.20 no.4
• /
• pp.5-15
• /
• 2002

For the noise reduction measures in a construction field where noise sources such as blasting and pile driving works exist, the construction of the sound barrier near the noise source or receiver is often the most economic measure in order to exclude the propagated sound. The dimension of the barrier is decided by the noise and construction design, and the constructive quality of a soundproof panel shall be secured in accordance with KS F4770 to guarantee the safety of sound barriers. In this paper the problems included in the KS F4770-1 that is the regulation for the metallic sound barrier of the absorption type are identified and it is suggested what to be corrected or improved. Through a series of the analyses, conclusion were reached that it is required to improve test methods in KS F4770-1 as well as to break down loads for building more cost-effective sound barrier. In addition, KS F4770-1 was compared with ZTV-Lsw 88 which is the german regulation for sound barrier design. As a result, it was found that the Korean regulation is more conservative than that of Germany.

• Aerospace Engineering and Technology
• /
• v.2 no.2
• /
• pp.33-44
• /
• 2003

This paper describes the design and analysis technology of composite flexure and composite paddle-type blade which are all key technologies on hingeless rotor system. Through replacing the existing metal or engineering plastic flexure part with composite part, Several required structural analysis were accomplished, which are static analysis by using NASTRAN and dynamic analysis by using FLIGHTLAB. The dynamic characteristics of composite hingeless hub attached with paddle-type blade was also investigated. Further more, small-scaled paddle-type blade was designed using froude scaled properties of existing full size blade. Through this design procedure of composite paddle-type blade, the structural design method was achieved. These results will be applied to accomplishing current project named as "the development of next-generation helicopter rotor system."

• Journal of Energy Engineering
• /
• v.10 no.3
• /
• pp.294-298
• /
• 2001

A research for transmutation reactor is in progress to transmute high radioactive isotopes into low radioactive ones. In this study, thermal-hydraulic and structural analysis was performed to design liquid metal target system that would be used in subcritical transmutation reactor. Diffuse plate installation was considered to enhance cooling of window. And thermal-structural analysis of window was performed varying window thickness, beam power, and coolant flow rate to determine target system design valuers. It is ensured that maximum window temperature and stress would be acceptable in the design condition.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.40-45
• /
• 1998

Th-232를 Fertile 핵연료로 사용한 압력관형 고전환 경수로심을 설계하였다. 토륨 Blanket은 10년 정도 노내에 위치시키고, 농축 우라늄 Driver는 매년 재장전하도록 설계하였다. Driver로는 $UO_2$핵연료와 U-10%Zr 금속 핵연료를 사용하였고, Blanket으로 이중 탄소 피막 핵원료를 ThO$_2$에 적용한 핵연료를 사용하였다. 핵연료봉의 구조는 울진 3/4호기 핵연료와 같은 재원으로 하였으며 육각형 격자 배열로 집합체를 구성하였다. Seed Bundle을 1년 단위로 교체하고 Blanket Bundled을 5년-10년간 노내에 위치시키는 경우 경수로보다는 높은 전환율 갖는 원자로를 설계할 수 있다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.20 no.6
• /
• pp.29-37
• /
• 2016

This paper proposes a shape optimization of the metal boss for a composite motor case using finite element analysis. For the structural safety and the weight reduction of the composite motor case, under the internal pressure, the fiber stress in the dome area and the tightening bolt stress are constrained and the boss weight is set to objective function, respectively. The response surface models are constructed for the performance characteristics by using response surface method. The significance of the design variables about the performance characteristics is evaluated through the ANOVA(analysis of variance) and the goodness of fit test for the constructed model is performed through the regression analysis. The SQP(sequential quadratic programming) algorithm is used for the optimization and the proposed method is verified by performing structural analysis for the optimum shape.