• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.661-664
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• 2008

As architectures have recently become high-risers and megastructured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but also internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete for precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1086-1096
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• 2011

In this paper, we present the trisection band-pass filter with a transmission zero at 2.63 GHz, which has a center frequency of 2.44 GHz, relative bandwidth of 5 %, and return loss of 18 dB, based on a multi-port ElectroMagnetic simulation. The coupling matrix for the trisection filter is calculated and this filter is transformed into band-pass filter prototype through a lossless 2-port circuit transformation. The J-inverter values and slope parameters of each individual resonator are computed using an EM simulation Y-parameters of the filter with multi port. The dimensions of desired filter are determined by matching the computed J-inverter and susceptance slope parameters to those of the prototype band-pass filter. Undesired cross-couplings are found to occur which does not appear in the prototype trisection filter. To overcome the problem of undesired couplings, the filter was optimized to satisfy the same frequency response of prototype filter. The validity of the proposed design method was verified through the implementation of the designed and optimized filter.

• Polymer(Korea)
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• v.34 no.2
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• pp.133-136
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• 2010

Effect of solution film processing conditions on the dimensional stability of TAC film which is used as protection film of liquid crystal display (LCD) has been studied under hot and humid environmental condition (65 $^{\circ}C$, 90%). In addition, the mechanical and optical property changes due to the dimensional instability were also investigated. It was found that the fast solvent evaporation due to the increasing of methylene chloride content in solvent mixtures and decreasing dope concentration caused the lowering of dimensional stability under hot and humid condition. This dimensional stability change also affected the mechanical and optical properties of TAC films as well.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.87-92
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• 2009

It has been considered only with the concerned regional damage costs whenever the restoration and flood control measures were established in Korea. If the relationship between regional flood frequency and damages is quantitatively analyzed, more resonable and reliable countermeasure for flood protection and restoration can be proposed. Historical data ('70~'07) about flood damage in Korea were utilized and analyzed to present such relationship using the point frequency analysis. Also, the quadrant analysis was employed to divide into 4 categories: high frequency-high damage, high frequency-low damage, low frequency-high damage, and low frequency-low damage. If the results from this study were utilized well in specific cities and counties in Korea, it would be helpful to establish the countermeasures and action plans for flood protection because it was possible to compare with the relationship between flood frequency and damage of each region. And it would be the fundamental data for estimating the effect of future flood protection plan.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.237-237
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• 2016

전세계적으로 기후변화에 따른 가용 수자원의 부족과 물 재해가 증가하고 있으며, 이에 따른 수자원 및 물산업의 중요성이 강조되고 있다. 또한 세계 수자원 시장이 점차 확대될 것으로 전망되어 공공기관 및 국내기업은 해외 시장 진출을 위한 다양한 사업을 진행하고 있다. 해외 수자원산업의 진출을 위해서는 해당 국가의 수자원 현황파악과 수자원개발 계획에 대한 면밀한 분석이 필요하며, 물수지 영향을 검토하기 위한 타당성 조사가 요구된다. 본 연구에서는 아시아 개발도상국의 수자원개발 계획과 특성을 비교하고 물수지 분석을 위한 자료의 가용성을 평가하고자 한다. 대상지역은 아시아 개발도상국인 3개 국가(베트남, 이란, 파키스탄)를 선정하였으며, 각 국가의 수자원개발 계획의 특징을 분석하였다. 우리나라 사례와 비교하기 위해 국가수자원 장기종합계획과 국가 간 이수 및 치수부문별 계획의 차이점과 특성을 분석하였으며, 국가별 수자원계획에 활용한 수요 및 공급부문별 자료 특성을 비교하였다. 본 연구결과는 해외 수자원산업 진출을 위한 기초자료로 활용될 수 있을 것으로 기대되며, 물수지 분석 및 평가를 통해 수자원개발 가능성을 정량적으로 제시하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.89-96
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• 2022

In this paper, to evaluate the output quality of the cementitious composite mixture for printing with the ME method for construction 3D printer, visual inspection of the output appearance and the dimensional error rate, compressive strength and flexural strength of the output were measured. As a result of the test, the mixing design with excellent output appearance was P1-2, P1-4, P2-5, P2-6, and the mixing design with good output appearance was P0-1, P1-1, P1-3, P1-6, P1-7 and P2-4. Of these mixing designs, P0-1 and P2-6 had the lowest dimensional error rates As a result of evaluating the compressive strength and flexural strength of the various mixing designs, the Mixing design with excellent output designs showed good mechnical properties. However, mixing designs with excellent mechanical properties does not necessarily have excellent output quality. Therefore, in order to accurately evaluate the output quality, it is judged that visual inspection and dimensional error rate inspection should be performed first, and then the mechanical characteristics should be reviewed.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1363-1367
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• 2005

본 연구에서는 우리나라의 민간단체에서 시행되고 있는 전국 강살리기 운동 사례를 조사하여 강살리기 운동의 현황과 전망 및 한계점을 분석하며, 앞으로의 바람직한 강살리기 운동의 방향을 제시하는 것으로 하였다. 이를 위하여 전국 강살리기 네트워크 참여 단체를 중심으로 각 단체의 활동 사례를 조사하여 이들 활동의 특성을 검토하고, 치수와 이수 및 하천환경 측면에서 운동의 현황과 한계점을 검토하여 이를 극복하는 방안을. 제시하며, 이를 바탕으로 지역 주민과 함께 하는 강살리기 사업의 방안도 모색하는 것으로 하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.168-172
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• 2005

내수침수로 인한 수해가 빈번하게 발생하고 있는 삽교천 유역 중하류부를 대상으로 하구에 위치한 삽교호와 유역에서 유일하게 홍수조절 기능을 갖춘 예당지가 이 지역의 침수특성에 미치는 영향을 분석하였다. 아울러 신속한 홍수배제와 홍수유출량 저감을 목적으로 삽교호 배수갑문을 증설하고, 예당지를 증고하여 홍수조절 용량을 확장하였을 경우의 효과를 침수면적, 침수시간, 연평균피해경감기대액 등 다양한 기준에 의해 검토하였다. 그 결과 내수침수 저감을 목표로 할 경우 외수범람방어 위주의 기존 치수계획과는 차별되어야 하는 요소를 확인할 수 있었고, 사업대상지역 및 치수계획의 목표에 적합한 대안을 선정하는데 필요한 각 홍수방어대안의 특성을 파악할 수 있었다.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.48-53
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• 1996

The role of the torquer in dynamically tuned gyroscope (DTG) is to erect the slanted rotor straight. This IBper presents the design method of the torquer. The torquer must satisfy the desired maximum angular velocity condition. The performance of magnet-residual flux density, maximum energy product, and so on-is limited by the material characteristics. So we should design the torquer with the limited condition that magnet performance is given. If the mechanical size of DTG is deter-mined, the dimension of the torquer is calculated and the space of the torquer becomes constant. Therefore, if we determine the diameter of the torquer coil, the number of coil turns is calculated automatically. Using these dimensions, we can calculate the torque and the scale factor. The maximum angular velocity is computed if we know the maximum current density. The analysis of the torquer was carried out by the 3-dimensional finite element method. The proposed algorithm of the torquer design was valid in comparison with the experimental data obtained from fabricated DTG.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.722-729
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• 2013

This paper presents the influence on the transmission characteristics of dimensional tolerances of rectangular waveguides usually used as a low-loss transmission line in the millimeter-wave band. We derived the Green's functions of the waveguide with eigenfunction expansion method. The reflection coefficient of the waveguide with a post is calculated by using internal impedance in order to investigate the influence of dimensional tolerances of the waveguide. In order to check the validity of the theoretical analysis, the calculated reflection coefficients are compared with the measured results.