• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.21-27
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• 2008

In this paper, we design and implement the upstream packet bandwidth allocation algorithm on OPNET-based DOCSIS 3.0 simulator including channel-bonding CM (Cable Modem)s. Previous DOCSIS CM could not support channel bonding, it has problem in upstream bandwidth allocation and determine the contention area. The proposed upstream bandwidth allocation algorithm has been improved the queuing time and success rate. For the simulation, we design the MAC frame structure with channel bonding supported CM and not. And then, this paper design and implement the CMTS node model, CM node model, CMTS process model, and CM process model.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.1-5
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• 2010

Recently, the transmission amount of information that each single person requires is growing by development of electron information communication technology. So in this paper we analysis the phase noise characteristics to obtain a most suitable of SNR performance request characteristic by BER on CATV transmission system that satisfy performance request DOCSIS 2.0 standard. Especially we get the parameter value of PLL that satisfy phase noise characteristic request standard using developed simulator. Presented method can be used to obtain a performance request standard connection performance request standard of high speed CATV transmission system in the future.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.78-80
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• 2006

전력계통망 및 수용가는 다양한 형태의 전력케이블 및 전력선이 연계된 분 배전망을 형성하고 있다. 특히, 이렇게 구성된 분 배전망은 하나의 전력계통으로서 연계된 전력망을 형성하고 있으며, 이를 전력선통신의 인프라로 활용할 수 있다. 최근 들어, 전력선통신 기술에 대한 연구가 활발히 진행되고 있으며, 계통에 연계된 부하와 분기선로 그리고 매질의 특성에 따라 통신환경이 달라진다. 특히 전송 주파수에 따른 신호의 감쇠, 연계된 부하의 종류와 이들 부하로 인한 잡음원의 유입 및 전송신호의 왜곡 등이 주요한 채널환경 요소이다. 본 논문에서는 상기 나열한 한계점을 극복하기 위한 대안으로 전력선 및 케이블의 매질특성을 평가하고, 이에 따른 전송신호의 영향을 분석, 연계된 다양한 부하들의 변동에 따른 통신환경의 변화 영향 그리고 통신성능에 미치는 영향을 분석하였으며, 또한 전력 케이블 및 선로의 특성과 부하변동 특성을 반영하여 구내용 전력케이블 기반의 UWB(Ultra Wide Band) 통신용 채널 환경을 모델링하는 방안을 제안하고자 한다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.109-114
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• 2019

Hydraulic pumps are widely used in fields such as machinery manufacturing, engineering and construction. Although the research on hydraulic engineering is mature, it is still necessary to examine various performance aspects in detail for specific applications. This paper will focus on the hydraulic pump used in special construction machinery that needs high temperature and high pressure resistance. It will analyze the theoretical design, structure and thermal characteristics of the pump system using the Fundamentals of Engineering (FE) method, and will measure the key tolerance parameters of the hydraulic pump to ensure the accuracy of the machining. Through this research, a good design method for the linear reciprocating type of hydraulic pump can be summarized.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.2
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• pp.75-90
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• 2015

As soil nails support a ground by the friction between nails and soils being reinforced, the length of soil nails is important factor for a ground stability. Thus, the soil nail length has to be accurately evaluated in order to secure a ground stability. The goal of this study is to suggest the applicability of the non-destructive method as the basic research for the evaluation of the soil nail length. First, the elastic and electromagnetic waves are adopted to select an applicable method for the soil nails connected by the coupler. Test results show that while the ultrasonic waves are not detected due to the coupler, the electromagnetic waves are free for the influence of the coupler. Second, electromagnetic waves are measured for combined soil nails with the length of 1 m~15 m for the investigation of the characteristics of electromagnetic waves. The travel time of the electromagnetic wave increases with an increase in the soil nail length. In addition, the ground cable is used to apply the electromagnetic waves to pre-installed soil nails. Test results show that the travel time of the electromagnetic wave by using the ground cable increases with an increase in soil nail length. This study demonstrates that the electromagnetic wave may be a promising method for the evaluation of the soil nail length.

• Geophysics and Geophysical Exploration
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• v.21 no.2
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• pp.103-111
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• 2018

The recent research aim of seismic trace interpolation is to effectively interpolate the data with spatial aliasing. Among various interpolation methods, the Matching Pursuit interpolation, that finds the proper combination of basis functions which can best recover traces, has been developed. However, this method cannot interpolate aliased data. Thus, the multi-component Matching Pursuit interpolation and moveout correction method have been proposed for interpolation of spatially aliased data. It is difficult to apply the multi-component Matching Pursuit interpolation to interpolating the OBC (Ocean Bottom Cable) data which is the multi-component data obtained at the ocean bottom because the isolation of P wave component is required in advance. Thus, in this study, we dealt with an effective single-component matching Pursuit interpolation method in OBC data where P-wave and S-wave are mixed and spatial aliasing is present. To do this, we proposed the Ricker wavelet based single-component Matching Pursuit interpolation workflow with moveoutcorrection and systematically investigated its effectiveness. In this workflow, the spatial aliasing problem is solved by applying constant value moveout correction to the data before the interpolation is performed. After finishing the interpolation, the inverse moveout correction is applied to the interpolated data using the same constant velocity. Through the application of our workflow to the synthetic OBC seismic data, we verified the effectiveness of the proposed workflow. In addition, we showed that the interpolation of field OBC data with severe spatial aliasing was successfully performed using our workflow.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.281-301
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• 2024

The power cable tunnels which are part of the underground transmission line project, are constructed using the shield TBM method. The disc cutter among the shield TBM components plays an important role in breaking rock mass. Efficient tunnel construction is possible only when appropriate replacement occurs as the wear limit is reached or damage such as uneven wear occurs. A study was conducted to determine the wear conditions of disc cutter using a deep learning algorithm based on real-time measurement data of wear and rotation speed. Based on the results of full-scaled tunnelling tests, it was confirmed that measurement data was obtained differently depending on the wear conditions of disc cutter. Using real-time measurement data, an algorithm was developed to determine disc cutter wear characteristics based on a convolutional neural network model. Distributional patterns of data can be learned through CNN filters, and the performance of the model that can classify uniform wear and uneven wear through these pattern features.

• Journal of Cadastre & Land InformatiX
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• v.51 no.2
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• pp.5-20
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• 2021

With the available national spatial information that started from the sinkholes that occurred nationwide in 2014 and integrated 15 areas of underground information, the Underground Spatial Integrated Map has been continuously maintained since 2015. However, until recently, as disasters and accidents in underground spaces such as hot water pipes rupture, cable tunnel fires, and ground subsidence continue to occur, there is an increasing demand for quality improvement of underground information. Thus, this paper attempted to prepare a plan to improve the quality of the Underground Spatial Integrated Map data. In particular, among the 15 types of underground information managed through the Underground Spatial Integrated Map, quality validation improvement measures were proposed for underground facility (structure-type) data, which has the highest proportion of new constructions. To improve the current inspection methods that primarily rely on visual inspection, we elaborate on and subdivide the current quality inspection standards. Specifically, we present an approach for software-based automated inspection of databases, including graphics and attribute information, by adding three quality inspection items, namely, quality inspection methods, rules, and flow diagram, solvable error types, to the current four quality inspection items consisting of quality elements, sub-elements, detailed sub-elements, and quality inspection standards.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.830-842
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• 2015

This paper aims to develop a SI(structural identification) technique using the kinetic energy optimization technique(KEOT) and the direct matrix updating method(DMUM) to decide on optimal location of sensors and to update FE model respectively, which ultimately contributes to a composition of more effective SHM. Owing to the characteristic structural flexing behavior of cable bridges, which makes them vulnerable to any vibration, systematic and continuous structural health monitoring (SHM) is pivotal for them. Since it is necessary to select optimal measurement locations with the fewest possible measurements and also to accurately assess the structural state of a bridge for the development of an effective SHM, a SI technique is as much important to accurately determine the modal parameters of the current structure based on the data optimally obtained. In this study, the KEOT was utilized to determine the optimal measurement locations, while the DMUM was utilized for FE model updating. As a result of experiment, the required number of measurement locations derived from KEOT based on the target mode was reduced by approximately 80 % compared to the initial number of measurement locations. Moreover, compared to the eigenvalue of the modal experiment, an improved FE model with a margin of error of less than 1 % was derived from DMUM. Finally, the SI technique for long-span bridges proposed in this study, which utilizes both KEOT and DMUM, is proven effective in minimizing the number of sensors while accurately determining the structural dynamic characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1252-1260
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• 1999

The HFC network has a architecture of a star topology in fiber optic trunks, and tree and branch topology is used in the part of coaxial cable. It is well known that the HFC upstream channel is noisy. Ingress, common mode distortion and impulse noise exist in the upstream channel. In order to provide Quality of Service(QoS) to users with real-time data such as voice, video and interactive services, the evolving IEEE 802.14 standard for HFC networks must include an effective priority scheme. The scheme separates and resolves collisions between stations in a priority order. It is important to simulate protocols under a practical environment. The proposed algorithm in this paper is simulated with the assumption that the collision detector made certain mistake due to noises. Simulation results show that the proposed algorithm is more efficient than existing tree-based algorithm under practical environment.