• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.1
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• pp.34-42
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• 2001

The new periodic array structure or frequency selective surface with polarizers characteristic is proposed. The present structure is constructed with two sheets or FSS material, spaced about one-eight wavelength apart, the dipole element orientations of the two sheets being almost perpendicular to each other. The methods of the spectral domain immittance and MoM are used to analyze electromagnetic scattering from this periodic array structure. To confirm the validity of the polrizer's functions or the new periodic array structure, frequency selective surfaces are fabricated, calculated values for the frequency response of the reflection and transmission loss are compared with measured values. Good correspondence has been observed between them. Good axial ratio has been also observed to be achieved in the proposed structure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.583-594
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• 1989

The strong nonliner dynamic behavior of mechanical systems in the presence of clearances are studied. The nonlinearity is induced from the assumed symmetric piecewise-linear characteristics for stiffness and damping by the contact and uncontact. Based on Stoker's assertion concering the reasoning beyond the occurrence of subharmonics, the nonlinear differential equation is converted to four nonlinear algebraic equations form the boundary conditions at the contact points. For a single contact per half exciting period, under the assumption of symmetric response, the steady-state solutions obtained are in agreement with those of numerical integration. Also a nondimen-sionalized formulation is made for the purpose of parametric studies.

• New & Renewable Energy
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• v.18 no.4
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• pp.64-69
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• 2022

Double-sided photovoltaic (PV) modules have received significant attention in recent years as a technology that can achieve higher annual energy production rates than single-sided modules. The shingled technology is a promising method for manufacturing high-density and high-power modules. These modules are divided by laser and joined with electrically conductive adhesives. The output efficiency of the divided cells depends on the division pattern and the electrode pattern, making it important to understand the output characteristics. In this study, the output characteristics of large-area double-sided light-receiving shingled cells with different split patterns and electrode patterns were investigated. The M6 size, with 6 divisions in the electrode pattern, had the highest efficiency when using 142 front fingers and 146 rear fingers. The M10 size, with 7 divisions, had the highest output when using 150 fingers equally in the front and rear. The M12 size, also with 7 divisions, showed the highest output characteristics when using 192 front fingers and 208 rear fingers.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.73-81
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• 2002

Nowadays , the grouted-reinforcing method, which is called FRP(Fiberglass-reinforced-plastic) pipe .reinforcing method, has been introduced in the community of pound reinforcements. The resistance to corrosion and chemical attack high strength to weight ratio, and ease of handling make these pipes a better alternative to steels in tunnel. However, to fully utilize FRP pipes as grouted reinforcing members at the face and the crown in tunnel, their mechanical properties and behaviors and the grout-reinforced underground have to be verified. Laboratory shear tests were conducted to evaluate the mechanical properties for FRP pipes, the grout-reinforced members and the grout-reinforced body of FRP pipes. According to the test results, it was observed that FRP pipes play a dominant role in shearing behavior of the grout-reinforced members and that their shearing resistance exerts after the shearing displacement increases to some extent.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.50-55
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• 2017

Foamed aluminum is an eco-friendly material that is reusable and safe against fire. These superior characteristics have many advantages in the field of building and construction and in cruise ships as sound absorbers. So far, the research on foamed aluminum has been focused on the sound absorption performance using the foaming ratio. Foamed aluminum, when compared with the existing sound absorbers such as glass wool or rock wool, has a better structural performance, and it can be installed on walls in many different ways. This study conducted experiments on the sound absorption characteristics considering the various applications of foamed aluminum. The effects of painting surfaces with the finishing material were compared to that of the normal surface, and the effects of vertical installation and hanging from the ceiling was compared with the effects of installing on the floor.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.105-105
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• 2011

국내 해양레저산업 중 세일요트산업은 현재 초기시장을 형성하고 있으나, 현재 정부의 해양레저 활성화 정책과 해양레저 인구 또한 관련 협회, 클럽 등의 중심으로 급속한 증가세를 이루고 있다. 이에 요트수요 증대에 따라 요트 관련 부품 소재의 경우에도 향후 그 수요가 대폭 증가할 것으로 예상되어지고 있으며, 그 중 요트용 돛(Sail)의 경우에는 전량 해외 수입에 의존하고 있어 제품개발을 통해 국산화함으로써 해외 제품의 수입대체가 요구되고 있다. 본 연구는 해외의 산업용 폴리에스터 원사로 제조된 요트세일 제품의 특성 및 성능 분석 결과와 국산 고강력 폴리에스터 소재로 제조된 요트 세일 개발 제품의 물성 및 성능을 비교 분석하고자 한다. 세일 제품 개발을 위해 해외 요트용 세일 제품을 분석한 결과, 소재는 고상중합형태의 폴리에스터 산업용 원사를 사용하여 직물자체의 고강도 및 저신도 특성발현을 위한 고밀도 제직을 실시한 것으로 분석 되었으며, 가공에서는 해양에서 사용하는 세일 직물의 특성 상 일광 및 자외선에 대한 내구성을 높이고, 황변을 방지할 수 있도록 하기 위해 직물표면에 멜라민계 수지를 이용한 함침방식의 특수코팅을 실시한 것으로 분석되었다. 이러한 해외 요트용 세일 제품의 분석결과를 바탕으로 국산 고강력 폴리에스터 고밀도 직물에 자외선 및 일광에 대한 내구성이 우수한 무황변 타입의 폴리에스터계 수지를 사용하여 단면 코팅으로 양면코팅 가공효과를 부여하는 나이프 방식의 특수코팅, 에이징 처리를 통해 세일을 제조하였다. 본 연구에서는 제조된 세일 직물 제품에 대해, 물리적 특성을 분석하기 위해 인장 강신도, 무게, 두께 및 주사전자현미경 관찰 등의 테스트를 실시하였으며, 세일 성능 분석을 위해 공기투과도, 일광견뢰도 자외선 조사 후 강도변화, 황변 Test 등의 테스트를 실시하여, 해외 선진 제품과 개발제품의 물성 및 성능에 대해 고찰하였다.

• Journal of the Korean Electrochemical Society
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• v.20 no.3
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• pp.49-54
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• 2017

We develop a ceramic composite separator prepared by coating $ZrO_2$ nanoparticles with a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer on a polyvinyl alcohol (PVA) mechanical support prepared by electrospinning technique to improve thermal properties. The gurley number of the ceramic composite separator shows much lower value than that of a PE separator even though it possesses the polymeric coating layer with ceramic nanoparticles. In addition, the proposed sample shows higher electrolyte uptake than PE separator, leading to enhancing the ionic conductivity of the proposed sample and, by extension, the rate discharge properties of lithium ion batteries. Thermal stability of the ceramic composite separator is dramatically improved without any degradation in electrochemical performance compared to the performance of conventional PE separators.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.152-156
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• 1999

We have developed the pulse-width variable Quenched Dye Laser (QDL). QDL consisted of the dye cell of 5 mm length containing a $2.5{\times}10^{-3}$[mol/l] solution of Rhodamine 6G and the cylindrical lens focal length of 150 mm and quenching mirror. QDL system was pumped by s XeCl excimer laser with 150 mJ pulse energy in a 20 ns pulse at 1 Hz repetition rate. Pulse-width of QDL was measured by a noncollinear intensity autocorrelator. The focused thckness was measured by changing the position of the focusing cylindrical lens. Pulse-width of QDL as a function of the focused thickness (273.0${\mu}{\textrm}{m}$~845.0${\mu}{\textrm}{m}$) varied continuously from 86 ps to 201 ps.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.13-22
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• 2001

This paper presents three dimensional structure of RF packages and the improvement effect of its electrical characteristics when implementing RF transceivers. We divided RF modules into several subunits following each subunit function based on the partitioning algorithm which suggests a method of three dimension stacking interconnection, PAA(pad area array) interconnection and stacking of three dimensional RF package structures. 224MHz ITS(Intelligent Transportation System) RF module subdivided into subunits of functional blocks of a receiver(RX), a transmitter(TX), a phase locked loop(PLL) and power(PWR) unit, simultaneously meeting the requirements of impedance characteristic and system stability. Each sub­functional unit has its own frequency region of 224MHz, 21.4MHz, and 450KHz~DC. The signal gain of receiver and transmitter unit showed 18.9㏈, 23.9㏈. PLL and PWR modules also provided stable phase locking, constant voltages which agree with design specifications and maximize their characteristics. The RF module of three dimension stacking structure showed $48cm^3$, 76.9％ reduction in volume and 4.8cm, 28.4％ in net length, 41.8$^{\circ}C$, 37% in maximum operating temperature, respectively. We have found that three dimensional PAA package structure is able to produce high speed, high density, low power characteristics and to improve its functional characteristics by subdividing RF modules according to the subunit function and the operating frequency, and the features of physical volume, electrical characteristics, and thermal conditions compared to two dimensional RF circuit modules.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.1
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• pp.48-56
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• 2017

The purpose of this study is to analyze the 'identity' found in constructional characteristics of Geumgok Hongneung, the first imperial tomb of Korean empire. In terms of "sameness", which states for internal self-cognition among ambivalent situations while consisting identity, Hongneung inherited the prosperity of the Chosun dynasty, possessed 'sustainability' related to Cheongryangri Hongneung of Empress Myeongseong, as well as revealed various 'identitification' of situations in order to expose self-esteem as emperor and imperial nations. On the other hand, in terms of "individuality" as an external self-cognition, the opposite phase of sameness, Hongneung is a mixture of the will of Emperor Gojong and Japanese intervention hence formed 5th styles of royal tombs through 'peculiarity' which distinguishes it from the original tradition. In addition, the value of Hongneung is that it actually reflects the confusing and difficult times of the old ages, and it also involves 'excellence' as the place of the according a state funeral of Emperor Gojong and provoking March First Independence Movement. Thus, Geumgok Hongneung is a recorded landscape that clearly reflects the times of royal tombs of the Chosun dynasty, the world cultural heritage, and also the historic landscape showing extraordinary landscape of unique characteristics, 'Hwangjereung'.