• Structural Engineering and Mechanics
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• 제39권4호
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• pp.559-578
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• 2011

In regions of high seismic risk, high-strength concrete (HSC) columns of tall buildings are designed to be fully ductile during earthquake attack by providing substantial amount of confining steel within the critical region. However. in areas of low to moderate seismic risk, the same provision of confining steel is too conservative because of the reduced seismic demand. More critically, it causes problematic steel congestion in the beam-column joints and column critical region. This will eventually affect the quality of concrete placing owing to blockage. To relieve the problem, the confining steel in the critical region of HSC columns located in low to moderate seismicity regions can be suitably reduced, while maintaining a limited ductility level. Despite the advantage, there are still no guidelines developed for designing limited ductility HSC columns. In this paper, a formula for designing limited ductility HSC columns is presented. The validity of the formula was verified by testing half-scale HSC columns subjected to combined high-axial load and flexure, in which the confining steel was provided as per the proposed formula. From the test results, it is evident that the curvature ductility factors obtained for all these columns were about 10, which is the generally accepted level of limited ductility.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.164-164
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• 2016

Radar rainfall estimates have been widely used in calculating rainfall amount approximately and predicting flood risks. The radar rainfall estimates have a number of error sources such as beam blockage and ground clutter hinder their applications to hydrological flood forecasting. Moreover, it has been reported in paper that those errors are inter-correlated spatially and temporally. Therefore, in the current study, we tested influence about spatio-temporal errors in radar rainfall estimates. Spatio-temporal errors were simulated through a stochastic simulation model, called Multivariate Autoregressive (MAR). For runoff simulation, the Nam River basin in South Korea was used with the distributed rainfall-runoff model, Vflo. The results indicated that spatio-temporal dependent errors caused much higher variations in peak discharge than spatial dependent errors. To further investigate the effect of the magnitude of time correlation among radar errors, different magnitudes of temporal correlations were employed during the rainfall-runoff simulation. The results indicated that strong correlation caused a higher variation in peak discharge. This concluded that the effects on reducing temporal and spatial correlation must be taken in addition to correcting the biases in radar rainfall estimates. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which was funded by the Korea Institute of Construction Technology.

• 한국위성정보통신학회논문지
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• 제3권1호
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• pp.41-47
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• 2008

우리 나라의 군 무선통신은 산악지형 등의 원인으로 가시선 통신의 제약이 많다. 군은 가시선 통신의 제약을 극복하기 위해 국방과학연구소 주도로 무궁화5호를 사용하는 아나시스 체계(군 위성통신체계)를 도입하여 운용 중에 있다. 현재 육상에서 운용하는 단말은 이동 후 고정 운용하거나 건물에 설치하여 고정 운용하는 단말이다. 미국 등 선진국의 예를 살펴보면 전세계를 대상으로 신속한 네트워크 중심의 작전을 펼치기 위해 이동 중에도 통신이 가능한 이동형 위성단말을 활발히 연구하고 있다. 본 논문에서는 이동 중 통신이 가능한 단말시스템의 구현을 위해 X대역과 Ka 대역의 링크버짓을 분석하고 서브시스템의 기술적 요구사항들을 분석하였다. 특히, 0.9m 안테나부의 3dB 빔폭을 기준으로, 안테나 추적장치의 구동정확도와 외란을 보상하는 신호처리 방안에 대해서 분석하였다. 또한 이동 중 장애물에 의한 단절을 최소화하기 위해 수신 동기 신호 감시를 통해 링크 단절 시 버스트 신호의 송신을 중단하고 단절이 해제되면 재전송하는 프로토콜에 대해서 분석하였다. 분석된 규격은 시제 제작에 사용되어 양산 배치의 위험요소 분석에 활용될 것이다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.521-521
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• 2015

This study evaluated the gap filler radar as an implementation of the 1.5 km CAPPI data in Korea. The use of the 1.5 km CAPPI data was an inevitable choice, given the topography of the Korean Peninsula and the location of the radar. However, there still exists a significant portion of beam blockage, and thus there has been debate about the need to introduce the gap filler radar (or, the gap-filler). This study evaluated the possible benefits of introducing gap-fillers over the Korean Peninsula. As a first step, the error of the radar data was quantified by the G/R ratio and RMSE, and the radar data over the Korean Peninsula were evaluated. Then, the gap-fillers were located where the error was high, whose effect was then evaluated by the decrease in the G/R ratio and RMSE. The results show that the mean values of the G/R ratio and RMSE of the 1.5 m CAPPI data over the Korean Peninsula were estimated to be about 2.5 and 4.5 mm/hr, respectively. Even after the mean-field bias correction, the RMSE of the 1.5 km CAPPI data has not decreased much to be remained very high around 4.4 mm/hr. Unfortunately, the effect of the gap-filler on the 1.5 CAPPI data was also found very small, just 1 - 2%. However, the gap-filler could be beneficial, if the lowest elevation angle data were used instead of the 1.5 km CAPPI data. The effect of five gap-fillers could be up to 7% decrease in RMSE.

• 한국수자원학회논문집
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• 제38권12호
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• pp.1039-1049
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• 2005

본 연구의 목적은 기상 레이더의 수문학적 활용성을 높이고자 최적의 레이더 강우를 추정하기 위해 관악산 레이더 자료를 대상으로 POD 분석기법을 활용하여 지형클러터 및 빔 차폐영역 등을 제거하고 Marshall-Palmer의 Z-R 관계식으로 레이더 강우를 추정한 결과 강우계 관측강우와 비교하여 시$\cdot$공간적으로 과소 모의하는 것으로 나타났다. 이러한 결과를 바탕으로 강우계 관측강우와의 실시간 보정기법을 소양강 유역을 대상으로 적용한 결과 평균 G/R 값은 $0.95\~1.32$로 적정분포를 보이고 평균편차는 $9\~28\%$ 범위로 감소되어 불확실성 또한 감소하는 것으로 나타났다. 한편, 편차가 보정된 최적 레이더 추정강우로 소양강 유역평균 강우량을 산정한 결과 관측강우와 비교하여 매우 잘 일치하는 것으로 나타났다. 따라서 실시간 편차보정 기법은 수문학적 유역평균 강우량 산정시 다소 과소추정되는 레이더 강우정보를 정확하게 보정할 수 있다는 측면에서 그 적용성이 우수한 것으로 판단된다.