네트형 토석류 방호시설에 작용하는 충격에너지에 따른 앵커부인장력 산정

김성태(Kim Sungtae),유한규(Yoo Hankyu) 한국방재학회 2018 한국방재학회논문집 Vol.18 No.2

네트형 토석류 방호시설의 안정성을 확보하기 위해서는 네트부의 설계뿐 아니라 전 시스템을 지지하는 앵커부의 설계도 중요하다. 그러나 설계된 네트의 형태와 에너지 흡수율에 따라 앵커에 작용하는 인장력이 달라지기 때문에 설계하기 어려울뿐만 아니라 국내에서는 앵커설계에 대한 지침이 제시되어 있지 않다. 이에 본 연구에서는 정재하 실험을 통해 개발된 브레이크 프레임에 대한 에너지흡수율을 평가하고, 실대형 실험을 통해 방호시설의 변형과 충격에너지에 따른 앵커부 인장력을 분석하였다. 일반적으로 충격에너지가 증가함에 따라 방호시스템의 최대 변위가 증가하고, 브레이크 프레임의 에너지 흡수율도 증가하는 경향을 나타내었다. 또한 앵커부에 작용하는 인장력도 증가하였다. 본 연구에서는 앵커설계 시 사용할 수 있는 충격에너지-인장력 간의 경험식을 실대형 실험결과를 바탕으로 제안하였다. 이는 향후 앵커설계 시 유용한 자료로 활용될 것으로 판단된다. In order to ensure the stability of net protection system for debris flow, not only the design of net but also the design of anchor which is supporting whole system is of equal importance. However, as the tensile forces acting in the anchor vary according to the net types and the energy absorption, it is not easy to design the anchor capacity for this protection system. The guidelines for anchor design are also not established yet in Korea. In this study, a specific brake frame was developed for this system and the energy absorption by the brake frame was estimated based on static load test. Based on full scale impact tests, the deformation of net protection system and tensile forces in the anchors were analysed according to impact energy level. Generally, as the impact energy increases, not only the maximum displacement of the protection system and the energy absorption by the brake frame increase, but the tensile forces acting in the anchor also increase. Based on the experimental results, an empirical relationship between the impact energy and tensile force was established which can be used in anchor design. The results obtained from this study are planned to be utilized for design of anchor in the future.

The Analysis of Protection Ratio and Its Effect of Interference-to-Noise Ratio for Digital Microwave System with Diversity

Kyoung-Whoan Suh,Won-Gyu Jang 한국전자파학회JEES 2006 Journal of Electromagnetic Engineering and Science Vol.6 No.3

In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 ㎓ system, with the space diversity of 25 m distance between antennas or the frequency diversity of △f/f =0.05, under 64-QAM and 60 ㎞ at BER 10??, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to -5.9 ㏈ or from 6.0 to -4.3 ㏈ for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.

Estimation of Anchor Capacity in Net Protection System with Brake Frame for Debris Flow Based on Impact Energy

하상귀,Turab H. Jafri,홍상현,김성태,윤지석,유한규 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1

New energy absorption devices have been developed for use in net-type debris flow protection systems. The capacity of the anchors in the system needs careful analysis because the anchors play a significant role in transmitting energy from the impacting debris to the ground. In this paper, an effective method is proposed for estimating the anchor capacity based on increasing energy levels and the effect of brake frames in the system. For this purpose, four test cases based on varying impact energy levels were developed and full-scale impact tests were performed. The maximum deformations and tensile forces developed in the system were recorded and analyzed. Thereafter, the performance of the net protection system in the presence and absence of brake frames was numerically analyzed using ABAQUS software, and the stress distribution in various system components was investigated. Based on the results of the full-scale impact tests and numerical analysis, a relationship between the total anchor capacity and impact energy level was established by considering the workability of the U-clips. This study demonstrates that approximately 40% reduced anchor capacity can be safely used for impact energy levels ranging from 50 to 200 kJ when brake frames are used in the system.

사면보강용 Expanded Metal 격자크기에 따른 인발 특성 연구

지영환(Ji Younghwan),김기환(Kim Kihwan),김성호(Kim Sungho),황영철(Hwang Yeongcheol),이승호(Lee Seungho) 한국지반환경공학회 2010 한국지반환경공학회논문집 Vol.11 No.12

국가 차원 사회 간접자본 투자증가로 도로 개설 및 확장 등으로 인해 도로 절개비탈면의 증가가 필연적 현상으로 나타나고 있다. 도로 절개 비탈면이 증가됨에 따라 매년 많은 인명피해와 재산 피해가 발생되고 있으며 국내에서는 이러한 낙석 및 산사태로 인한 피해를 저감하고자 하는 취지에서 많은 연구가 수행되고 있다. 일반적으로 국내 도로사면의 대부분은 국토해양부에서 발간한 “도로안전시설 설치 및 관리지침”에 근거한 표준낙석방지시설을 사용하고 있으나 이러한 낙석방지시설이 실제 낙석 발생 시 큰 파손 없이 낙석을 방어할 수 있는 지에 대해서 많은 의문점들이 제기되고 있다. 또한 기술수준이 미약하여 전체적으로 해외 기술력에 의존하고 있으며, 낙석방지망의 경우 부분적 취약점(일체화가 되지 못함)으로 인해 충분한 지지능력을 발휘하지 못하고 망이 터지는 문제점 등이 발생됨에 따라 국내에서도 보다 높은 낙석 에너지를 지지할 수 있는 낙석방지망에 대한 연구가 필요할 것으로 판단된다. 이에 본 연구에서는 낙석방지망으로써의 적용가능한 Expanded Metal(3.2T)을 대상으로 낙석방지망 인발시험을 실시하여 망 크기에 따른 하중-변위 특성 및 파괴형태를 분석하여 Expanded Metal 낙석방지망의 경제적이고 합리적인 규격을 판단하는데 기초자료로 제공하고자 하였다. The construction of new roads and the consistent extension of already-existing roads or the line-shape revision of those roads are increased with the governmental investment to SOC facilities currently. Accordingly, the road cut slopes are in the trend of rapidly increasing. As the road slope has increased, a lot of human and property damages has entailed consequently and in the local case, numerous studies have carried out aiming at minimizing this damages caused by the rockfall and landslide. In general, standard falling rock prevention facility has employed for most of the local road slope based on “Guide for Installation and Management of Road Safety Facilities” published by MLTM(the Ministry of Land, Transport, and Maritime Affairs) but profound doubt has raised as to whether this rockfall prevention facility would function properly enough to prevent rockfall efficiently without any damages in case of actual occurrence of rockfall. In addition, it is a reality that in most cases, such work is relied on overseas technology as a whole as the local technical level is low and in case of rockfall prevention net, it is judged that a study on rockfall prevention net that is able to endure more powerful rockfall energy is required as the problem including net bursting is taken place as a result of enough bearing force being failed to be demonstrated due to its partial weak point(not uniformly made). Under this background, in this study, three kinds of model depending on mesh size of expanded metal that is considered to have an adoptability as rockfall prevention net, as target are selected and characteristics depending on mesh size of expanded metal is intended to be researched through a pull-out test performance by using pull-out test equipment rockfall prevention net.

A Protection Ratio with Composite Fade Margin for Detailed Frequency Coordination in Microwave Relay System Network

Kyoung-Whoan Suh 한국전자파학회JEES 2007 Journal of Electromagnetic Engineering and Science Vol.7 No.2

In this paper, the formulation of the protection ratio based upon a composite fade margin and availability is newly presented for the detailed planning of frequency coordination in the microwave relay system network, and computed results for co-channel and adjacent channel protection ratios are illustrated over an actual system with 6.2 ㎓. It is shown that the protection ratio to assure a quality of service can be expressed in terms of the composite fade margin, noise-to-interference ratio, net filter discrimination, and system parameters. In addition, the net filter discrimination, depending upon the transmitter spectrum mask and the overall receiver filter characteristic, has been examined to investigate the effect of the adjacent channel protection ratio caused by the adjacent channel interference. Regarding simulated results for 6.2 ㎓, 60 km, 64-QAM, and N/I=6 ㏈ at the bit error rate of 10??, composite fade margin and co-channel protection ratio yield 25.14 and 50.3 ㏈, respectively. Also, the net filter discrimination of 26.5 ㏈ and the adjacent channel protection ratio of 23.8 ㏈ are obtained at the first adjacent channel of 30 ㎒. The proposed method provides some merits in view of a comprehensive and practical application with more detailed and various system parameters needed to access the criteria for making the proper frequency coordination.

A Derivation of Comprehensive Protection Ratio and Its Applications for Microwave Relay System Networks

Kyoung-Whoan Suh 한국전자파학회JEES 2006 Journal of Electromagnetic Engineering and Science Vol.6 No.2

This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current microwave frequency band of 6.7 ㎓ including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 ㏈, respectively, for 64-QAM and 60 km at BER 10??. It is shown that the net filter discrimination with 40 ㎒ channel bandwidth provides 28.9 ㏈ at the first adjacent channel, which yields 46.3 ㏈ of adjacent channel protection ratio. In addition, the protection ratio of 38 ㎓ radio relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.

M/W 중계 시스템 망의 주파수 조정을 위한 보호비 계산에 대한 연구

서경환,Suh Kyoung-Whoan 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.2

본 논문에서는 마이크로파 중계 시스템 망의 주파수 조정에 적용할 수 있는 효율적인 보호비 산출 방법을 제안하고 결과를 제시한다. 또한 인접 채널 보호비를 계산하기 위해 송신 스펙트럼 마스크와 수신 필터 특성에 관련된 통합 필터 변별도(NFD)를 고찰하였다. 보호비는 변조 방식에 따른 신호-대-잡음 비, 잡음-대-간섭 비, 다중 간섭 허용, 다중 경로 또는 강우 감쇠의 페이드 마진, 통합 필터 변별도의 변수들로 구성된다. 주파수 6.7 GHz, 64-QAM, 거리 60 km, BER $10^{-6}$에서 계산된 페이드 마진 및 보호비는 각각 41.1 및 75.2 dB를 얻을 수 있었다. 채널 대역폭 40 MHz의 NFD는 첫 번째 인접 채널에서 28.9 dB가 되며, 이로부터 첫 번째 인접 채널의 보호비는 46.3 dB가 됨을 알 수 있었다. 또한 실제 중계망의 적용을 위해 채널 대역폭 20 및 40 MHz를 갖는 이종 시스템간의 NFD 및 보호비도 고찰하였다. 제안된 방법은 계산의 용이성과 체계적 확장, 그리고 밀리미터파 중계망의 주파수 조정에도 동일한 개념을 적용할 수 있는 장점을 갖는다. This paper suggests an efficient method of protection ratio calculation and shows some results applicable to frequency coordination in microwave(M/W) relay system networks, and the net filter discrimination(NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively. NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. In addition, NFD and protection ratio for different systems with channel bandwidth 20 and 40 MHz have been investigated to be used for actual M/W networks. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

합성 페이드 마진 및 가용율에 근거한 M/W 중계 시스템의 보호비 유도 및 계산

서경환,이주환,Suh, Kyoung-Whoan,Lee, Joo-Hwan 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.3

본 논문에서는 주파수 조정의 상세 계획에 적용할 목적으로 M/W 중계망의 보호비 유도를 새로이 제안하였으며, 실제 시스템 및 주파수에 대해 동일 및 인접 채널 보호비의 계산 결과를 제시하였다. 가용율 예측에 근거한 제시된 방법은 합성 페이드 마진, 간섭-대-잡음의 비(I/N), 통합 필터 변별도, 시스템 변수로 나타낸 것이다. 계산 결과에 의하면 6.7 GHz, 60 km, 64-QAM, I/N=-6 dB, $BER=10^{-6}$에서 합성 페이드 마진 및 동일 채널 보호비는 각각 25.5 및 50.7 dB을 갖는다. 또한 40 MHz 인접 채널에 대해 통합 필터 변별도 및 인접 채널 보호비는 26.3 및 24.4 dB을 얻는다. 제안된 방법은 M/W 중계망의 보호비 도출에 있어 보다 상세하고 다양한 장치의 변수를 고려한 확장의 용이성 및 실용성 측면에서 이점을 갖는다. In this paper, the derivation of protection ratio is newly proposed for the detailed planning of frequency coordination in microwave relay networks, and computed results for protection ratio of co-channel and adjacent channel are illustrated over the actual system and its frequency. It is shown that the suggested method based upon availability prediction can be expressed in terms of composite fade margin, interference-to-noise ratio(I/N), net filter discrimination, and system parameters. According to results, for 6.7 GHz, 60 km, 64-QAM, and I/N= -6 dB at BER $10^{-6}$, composite fade margin and co-channel protection ratio provide 25.5 and 50.7 dB, respectively. Also, net filter discrimination and adjacent channel protection ratio are obtained as 26.3 and 24.4 dB, respectively, at the first adjacent channel of 40 MHz. The proposed method provides some merits in computing protection ratio for microwave relay networks in view of an easy extension and practical applications considering more detailed and various system parameters.

퍼지 페트리네트를 이용한 전력계통 보호시스템의 모델링과 고장진단

최진묵,노명균,홍상은 순천향대학교 부설 산업기술연구소 1999 순천향 산업기술연구소논문집 Vol.5 No.2

As the complexity of power systems increases, especially in the case of multiple faults or ncorrect operation of protective devices, fault diagnosis requires new and systematic methods to the reasoning process, which improves both its accuracy and its efficiency. Therefore this paper proposes a method of the modeling of protection systems and fault diagnosis in power systems using Fuzzy Petri Nets (FPN). The proposed method can reduce processing time and increase accuracy when compared with the traditional methods. And also this method can cover online processing of real-time data from SCADA (Supervisory Control and Data Acquisition).

인접 채널 간섭 분석을 위한 고정 무선 중계 시스템의 NFD 및 보호비 계산에 대한 연구

서경환,Suh Kyoung-Whoan 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.11

본 논문에서는 인접 채널 간섭 분석을 위한 통합 필터 변별도(NFD)의 수식과 계산을 고찰하며, 이를 근거로 고정 무선 중계망의 주파수 조정에 필요한 동일 채널 및 인접 채널 보호비 산출을 위한 체계적인 알고리즘을 제시한다. 인접 채널 보호비를 페이드 마진, 변조 방식, 허용 간섭의 함수로 표현된 동일 채널 보호비와 송신스펙트럼 마스크 및 수신기 필터 특성에 의존하는 NFD의 계산 결과로 구할 수 있음을 보인다. 실제 계산을 보이기 위해 6.2 및 6.7 GHz 대역의 29.65 및 40 MHz 채널 대역폭에 대한 각각의 스펙트럼 마스크와 수신기 필터 특성으로 NFD를 구하였다. 결과에 의하면 29.65 및 40 MHz 채널에 대한 첫 번째 인접 채널의 NFD는 각각 27.4 및 28.9 dB을 얻었다. 이러한 결과로부터 거리 60 km, 64-QAM에 대해 채널 대역폭 29.65 및 40 MHz의 인접 채널 보호비는 각각 47.5 및 46.3 dB이 됨을 알 수 있었다. 제안된 방법은 계산이 용이하고 체계적인 확장과 밀리미터 무선 중계망의 주파수 조정에도 적용되는 이점이 있다. This paper makes a study of a formulation of net filter discrimination(NFD) and its computation for analyzing adjacent channel interference and suggests a systematic algorithm for calculating protection ratios of co-channel and adjacent channel applicable to frequency coordination in the fixed radio relay networks. It is shown that adjacent channel protection ratio can be derived from two factors: One is NFD depending upon receiver filter characteristic as well as transmitter spectrum mask and the other is co-channel protection ratio given by a function of fade margin, modulation scheme, and allowable interference. Actually to show the computing procedure from transmitter spectrum mask and receiver filter characteristic, NFD has been obtained for channel bandwidth of 29.65 and 40 MHz at 6.2 and 6.7 GHz band, respectively. According to the results, NFDs at the first adjacent channel of 29.65 and 40 MHz provide 27.4 and 28.9 dB, respectively. From these data, adjacent channel protection ratios corresponding to each channel bandwidth yield 47.5 and 46.3 dB for a given 64-QAM and 60 km. The proposed method gives some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter radio relay networks.