Slip-line법을 이용한 V형 암석 노치의 파괴하중 계산

이연규(Youn-Kyou Lee) 한국암반공학회 2020 터널과지하공간 Vol.30 No.4

2차원 응력조건에서 V형 암석노치의 파괴하중을 계산하는 해석적 절차를 slip-line 소성해석법 기반으로 개발하였다. 노치 주변의 암석이 소성상태에 있을 때 slip-line 중 하나인 ɑ선이 암석 노치 면과 노치 외부 수평면을 연결한다는 사실과 ɑ선을 따라서 변하지 않는 불변량이 존재한다는 이론적 사실이 해석적 절차 개발과정에서 핵심 아이디어로 활용되었다. 암석 노치 외부 수평면의 응력 경계조건을 알고 있으므로 불변량 방정식을 풀면 암석 노치 면에 작용하는 수직응력과 전단응력을 계산하는 것이 가능해진다. 노치 면에 작용하는 응력성분 값을 이용하여 쐐기에 의해 노치에 가해지는 파괴하중을 계산하였다. 개발된 해석적 절차를 적용하여 암석 노치파괴 해석을 수행하였다. 암석 노치의 파괴하중은 노치의 각도 및 노치 면의 마찰이 증가함에 따라 지수함수적 비선형성을 가지고 증가하는 특성이 있음을 해석결과는 보여주었다. 이 연구에서 개발한 해석적 절차는 쐐기형 노치 형성을 통한 암석균열 개시조건 연구, 암반 기초 지지력 계산, 암반사면 및 원형터널의 안전성 해석 등에 응용될 수 있을 것으로 기대된다. An analytical procedure for calculating the failure load of a V-shaped rock notch under two-dimensional stress conditions was developed based on the slip-line plastic analysis method. The key idea utilized in the development is the fact that the ɑ-line, one of the slip-lines, extends from the rock notch surface to the horizontal surface outside the notch when the rock around the notch is in the plastic state, and that there exists an invariant which is constant along the ɑ-line. Since the stress boundary condition of the horizontal surface outside the rock notch is known, it is possible to calculate the normal and shear stresses acting on the rock notch surface by solving the invariant equation. The notch failure load exerted by the wedge was calculated using the calculated stress components for the notch surface. Rock notch failure analysis was performed by applying the developed analytical procedure. The analysis results show that the failure load of the rock notch increases with exponential nonlinearity as the angle of the notch and the friction of the notch surface increase. The analytical procedure developed in this study is expected to have applications to the study of fracture initiation in rocks through wedge-shaped notch formation, calculation of bearing capacity of the rock foundation, and stability analysis of rock slopes and circular tunnels.

API X70 및 X80 라인파이프강의 DWTT 특성에 미치는 시편 두께와 노치 형태의 영향

신상용 ( Sang Yong Shin ),황병철 ( Byoung Chul Hwang ),이성학 ( Sung Hak Lee ),강기봉 ( Ki Bong Kang ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.5

In the present study, effects of specimen thickness and notch shape on drop weight tear test (DWTT) properties of API X70 and X80 line-pipe steels fabricated by varying hot-rolling conditions were investigated. The DWTT was conducted on the rolled steels, and the results were discussed in comparison with the Charpy V-notch (CVN) impact test and crack tip opening angle (CTOA) test data. The DWTT results indicated that the steels rolled in the single phase region had the higher upper shelf energy (USE) than the steel rolled in the two phase region because their microstructures were composed of acicular ferrites, which was similar to the CVN test results. The DWTT energy transition temperature (ETT) increased with increasing specimen thickness due to the increase in constraint state, and the ETT of the Chevron notch DWTT was slightly higher than that of pressed notch DWTT. The measured CTOA showed better correlation with the DWTT propagation energy than with the CVN or DWTT total energy as it was related with the crack propagation speed. Since the value of sin(2CTOA) was linearly proportional to the DWTT energy, it could be used as a useful parameter to estimate the CTOA.

액시얼 피스톤 펌프(피스톤수 짝수형)에서 맥동저감라인 설계 및 성능 평가

최세령(S. R. Choi),이일영(I. Y. Lee),지상원(S. W. Ji) 유공압건설기계학회 2018 유공압건설기계학회 학술대회논문집 Vol.2018 No.11

Axial Piston Pumps are generally designed with an odd number of pistons in trying to reduce kinetic flow ripple, however, they are also designed with an even number of pistons for more effectiveness in the pulsation reduction design. In this paper, a pulsation reduction line is designed with no check valve by arranging a cylinder block notch for the pumps with an even number of pistons. By adding notches to the outer circumferential direction of the cylinder blocks, it produces a separate path from the existing discharge and suction ones. Also, PRL connection angle is designed in accordance with the shape of cylinder block notch. From an experiment to study the pressure pulsation & volumetric efficiency by using the commercial pumps with 10 pistons, the performance of PRL which used the cylinder block notch was verified by showing significant reduction in flow ripple.

전력선 통신 시스템을 위한 고성능 Notch Filter 알고리즘 구현

남윤호,장동원,김경석 한국인터넷방송통신학회 2010 한국인터넷방송통신학회 논문지 Vol.10 No.3

전력선은 이미 전 세계적으로 60% 이상의 주거지에 설치되어 있기 때문에 고속의 전력선 통신을 이용하여 인터넷 액세스를 실현하는 새로운 액세스용 회선을 부설하지 않고 광대역 서비스를 제공할 수 있다. 이러한 이유로 정보화 시대에 인터넷 망이 닿지 않는 Last Mile Solution에 가장 적합한 서비스로서 전력선 통신에 대한 연구가 이루어지고 있다. 하지만, 전력선은 통신 선로가 아니고 전력을 전송하도록 설계되었기 때문에 전자파의 누설로 부근의 무선통신 시스템에 영향을 주게 된다. 본 논문에서는 기존의 무선 통신 서비스와 전력선 통신과의 간섭을 줄이기 위하여 기존의 Notch Filter보다 성능 면에서 우수한 고성능 Notch Filter 알고리즘을 제안하였다. 또한, 고성능 Notch Filter를 적용하여 임베디드 보드를 통한 Notch Filter Emulator를 구현하였다. As Power Line has been already installed over 60% of a residential area all over the world, Broadband Service has been possible using high-speed PLC(Power Line Communication) without new access line installed for Internet access. Because of such reason, PLC is researched as the most suitable service for Last Mile Solution. But, Power Line is designed for transmitting electric power, so peripheral Wireless Communication System is affected by a leak of electric wave. In this paper, we propose a High Performance Notch Filter algorithm in comparison with a existing notch filter for reduction of interference between existing Wireless Communication Service and Power Line Service. In addition, we implement the Notch Filter emulator appling a High Performance Notch Filter and using a embedded board.

Al6061-T6 평판 시편의 노치반경과 두께가 파괴 메커니즘에 미치는 영향

두샤오(Xiao Du),왕량(Liang Wang),최낙삼(Nak-Sam Choi) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.3

Al6061-T6 합금의 연성파괴는 네킹의 발생 시에 생기는 삼축인장응력과 관계가 있다. 노치 반경과 두께에 따른 시편 표피와 내부의 응력상태가 달라진다. 본 연구에서는 두께 4 mm, 8 mm의 평판으로 노치 없는 시편(un-notched), 노치 반경이 큰 시편(L-notched, R228.1 mm), 노치 반경이 작은 시편(S-notched, R2.5 mm)을 제작하였다. 슬립라인 이론(slip line theory), 타원기준(ellipse criterion), 유한요소법(FEM), 2D 디지털 이미지 상관법(2D-DIC)을 이용하여 노치 반경과 두께에 따른 응력상태와 파괴위치를 해석하였으며 주사 전자현미경(SEM) 관찰을 병행하여 파괴 양상을 관찰하였다. 노치반경이 작을수록 응력집중으로 인해 시편 내부에 형성한 높은 삼축인장응력이 파괴를 주도하였다. 두께가 커지면 파괴는 삼축인장응력과 최대전단응력에 의한 혼합모드의 파괴거동을 보였다. The fracture behavior of Al6061-T6 alloy is related to stress triaxiality formation during the local necking process of the specimen. Distribution of triaxial tensile stress varies with different notch radii and specimen thickness. In this study, plate specimens (un-notched), specimens with large notch radius (L-notched, R228.1 mm), and specimens with small notch radius (S-notched, R2.5 mm) were made of aluminum alloy plates (thickness 4 mm, 8 mm). Slip line theory, the ellipse criterion, finite element method (FEM), and 2D digital image correlation (2D-DIC) were used to find the effect of notch radii and specimen thickness on stress state distributions and initial fracture mechanisms. A scanning electron microscope (SEM) was used to observe the initial fracture surface. For a small notch radius causing high stress concentration, the fracture began at a site close to the notch tip due to high triaxial tensile stress. With increasing specimen thickness, the fracture surface showed a mixed mode failure behavior caused by both the triaxial tensile stress and maximum shear stress.

스펙트럼 센싱 기반 전력선 통신 시스템 구현

이현소(Hyun-So Lee),남윤호(Yun-Ho Nam),홍무현(Moo-Hyun Hong),장동원(Dong-Won Jang),이영환(Young-Hwan Lee),김경석(Kyung-Seok Kim) 한국콘텐츠학회 2009 한국콘텐츠학회논문지 Vol.9 No.11

인터넷 서비스가 주 정보원으로 작용하는 정보화 시대에 인터넷 망이 닿지 않는 지역에 인터넷 서비스를 제공하기 위해 전력선 통산이 이루어지고 있다. 하지만, 전력선은 통신 선로가 아니므로 통신 신호의 흐름에 따라 방사되는 전파가 발생하고, 그 전파는 기존에 그 대역을 사용하는 무선 통신 서비스와 간섭이 발생하게 된다. 본 논문에서는 전력선 통신과 무선 통신 서비스의 상호 간섭을 줄이기 위해 스펙트럼 센싱 기술과 Notch Filter 적용 방안을 제안하였다. 스펙트럼 센싱은 주변의 허가된 무선국을 보호하기 위해 주변 무선 환경을 탐색하여 빈 주파수 대역을 찾아 임시적으로 주파수 대역을 사용할 수 있도록 하는 Cognitive Radio(CR)기술의 핵심 기술이다. 또한, 각각의 스펙트럼 센싱 모듈과 Notch Filter의 기능들을 임베디드 보드를 통하여 구현하였다. Today, Internet service is a most important Information Source. So, the Power Line Communication has been achieved to offer Internet service to Last-Mile area. But, Power Line is not suitable for communication, So, electromagnetic wave is generated from Power Line during flow of communication information. And the electromagnetic wave is interfered with Wireless Communication Service using the same frequency range. In this paper, the Notch Filter and the Spectrum Sensing technology are proposed to reduction of interference between Power Line Communication and Wireless Communication Service. The Spectrum Sensing technology is the core technology of the Cognitive Radio (CR) system. CR is the technology that temporarily allocates the frequency bandwidth by scanning surrounding wireless environments to keep licensed terminals and search the unused frequency bandwidth. The proposed emulator is implemented with Spectrum Sensing and Notch Filter system using Embedded Board.

Band-Notched Ultra-Wideband Antenna with Asymmetric Coupled-Line for WLAN and X-Band Military Satellite

Jun-Hyuk Lee,Young-Je Sung 한국전자파학회JEES 2013 Journal of Electromagnetic Engineering and Science Vol.13 No.1

This paper presents a novel ultra-wideband (UWB) antenna that rejects narrow and broad bands and is suitable for wireless communications. The base of the proposed antenna has a circular patch that can cover the UWB frequency range (3.1~10.6 GHz). The interference issues caused by co-existence within the UWB operation frequency are overcome by a design that uses a parallel-coupled asymmetric dual-line with a circular monopole antenna. The proposed antenna showed a stable radiation pattern, realized gain and reflection coefficient lower than ?10 dB across the UWB operation bandwidth except for 5.15~5.85 GHz and 7.25~8.4 GHz. The fabrication, simulation, and measurement results obtained for the proposed antenna were in good agreement with the expected values.

전력선통신을 위한 동적 고성능 Notch Filter 구현

신성균,이병진,장동원,김경석 한국인터넷방송통신학회 2013 한국인터넷방송통신학회 논문지 Vol.13 No.1

최근 인터넷이 주 정보원으로 작용하고 인터넷의 보급이 확산되는 정보화시대에 인터넷 망이 닿지 않는 지 역의 Last Mile Solution에 적합한 대안으로서 전력선 통신에 관한 연구가 진행되고 있다. 하지만, 전력선 통신은 전 력을 전송하도록 설계되었기 때문에 높은 고주파 신호를 보내게 되면 부근의 무선통신 서비스에 영향을 주게 된다. 이러한 간섭을 제거하기 위해서 일반적인 방법으로는 Notch filter를 주로 사용한다. 본 논문에서는 WDF 방식을 적용 한 동적 고성능 Notch filter를 MATLAB을 통해 성능을 확인하였고 TI사의 TMS320C6416T DSP 보드를 이용하여 구 현하였다. Recent studies have been conducted on powerline communications as a viable alternative to the spread of the spread of the Internet and the Internet as the chief source of information act in the information age, the internet does not reach local Last Mile Solution. Powerline communication, but because it has been designed to transfer power to the high frequency signal to be sent when the close of wireless communications services impacted. The notch filters of a common way to eliminate the interference are used. In this paper, a dynamic high-performance notch filter applying WDF performance was verified through MATLAB and was implemented using a TI's TMS320C6416T DSP board.

Compact Band-notched UWB Antenna Design Based On Transmission Line Model

Xiaoming Zhu,Xiaodong Yang,Peng Chen 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

In order to avoid the interference from existing narrowband communication systems, this paper proposes a compact band-notched UWB (ultra wideband) antenna with size of 12mm×22mm ×1.6mm. Transmission line model is applied to analyzing wide impedance matching characteristic of the modified base antenna, which has a gradual stepped impedance feeder structure. The proposed antenna realizes dual band-notched function by combining two biased T-shaped parasitic elements on the rear side with a window aperture on the radiation patch. The simulation current distributions of the antenna reflect resonant suppression validity of the two methods. In addition, the measured radiation characteristics demonstrate the proposed antenna prevents signal interference from WLAN (5.15-5.825GHz) and WiMAX (3.4-3.69GHz) effectively, and the measured patterns show the antenna omnidirectional radiation in working frequencies.

Compact Band-notched UWB Antenna Design Based On Transmission Line Model

Zhu, Xiaoming,Yang, Xiaodong,Chen, Peng The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

In order to avoid the interference from existing narrowband communication systems, this paper proposes a compact band-notched UWB (ultra wideband) antenna with size of $12mm{\times}22mm{\times}1.6mm$. Transmission line model is applied to analyzing wide impedance matching characteristic of the modified base antenna, which has a gradual stepped impedance feeder structure. The proposed antenna realizes dual band-notched function by combining two biased T-shaped parasitic elements on the rear side with a window aperture on the radiation patch. The simulation current distributions of the antenna reflect resonant suppression validity of the two methods. In addition, the measured radiation characteristics demonstrate the proposed antenna prevents signal interference from WLAN (5.15-5.825GHz) and WiMAX (3.4-3.69GHz) effectively, and the measured patterns show the antenna omnidirectional radiation in working frequencies.