• Title/Summary/Keyword: Obstacle model

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Characteristics of the Progressive Brittle Failure around Circular Opening by Scaled Model Test and Discrete Element Analysis (축소 모형시험과 개별 요소 해석에 의한 원형 공동 주변의 점진적 취성파괴 특성에 관한 연구)

  • Jeon Seok-Won;Park Eui-Seob;Bae Seong-Ho
    • Tunnel and Underground Space
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    • v.15 no.4 s.57
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    • pp.250-263
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    • 2005
  • Progressive and localized brittle failures around an excavated opening by the overstressed condition can act as a serious obstacle to ensure the stability and the economical efficiency of construction work. In this paper, the characteristics of the brittle failure around an circular opening with stress level was studied by the biaxial compressive test using sealed specimen and by the numerical simulation with PFC2DPFC2D, one of the discrete element codes. The occurring pattern and shape of the brittle failure around a circular opening monitored during the biaxial loading were well coincided with those of the stress induced failures around the excavated openings observed in the brittle rock masses. The crack development stages with stress level were evaluated by the detailed analysis on the acoustic emission event properties. The microcrack development process around a circular opening was successfully visualized by the particle flow analysis. It indicated that the scaled test had a good feasibility in understanding the mechanism of the brittle failure around an opening with a high reliability.

Passenger Ship Evacuation Simulation Considering External Forces due to the Inclination of Damaged Ship (손상 선박의 자세를 고려한 여객선 승객 탈출 시뮬레이션)

  • Ha, Sol;Cho, Yoon-Ok;Ku, Namkug;Lee, Kyu-Yeul;Roh, Myung-Il
    • Journal of the Society of Naval Architects of Korea
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    • v.50 no.3
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    • pp.175-181
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    • 2013
  • This paper presents a simulation for passenger ship evacuation considering the inclination of a ship. In order to describe a passenger's behavior in an evacuation situation, a passenger is modeled as a rigid body which translates in the horizontal plane and rotates along the vertical axis. The position and rotation angle of a passenger are calculated by solving the dynamic equations of motions at each time step. To calculate inclined angle of damaged ship, static equilibrium equations of damaged ship are derived using "added weight method". Using these equations, physical external forces due to the inclination of a ship act on the body of each passenger. The crowd behavior of the passenger is considered as the flock behavior, a form of collective behavior of a large number of interacting passengers with a common group objective. Passengers can also avoid an obstacle due to penalty forces acting on their body. With the passenger model and forces acting on its body, the test problems in International Maritime Organization, Maritime Safety Committee/Circulation 1238(IMO MSC/Circ.1238) are implemented and the effects of ship's inclination on the evacuation time are confirmed.

Context Aware Feature Selection Model for Salient Feature Detection from Mobile Video Devices (모바일 비디오기기 위에서의 중요한 객체탐색을 위한 문맥인식 특성벡터 선택 모델)

  • Lee, Jaeho;Shin, Hyunkyung
    • Journal of Internet Computing and Services
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    • v.15 no.6
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    • pp.117-124
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    • 2014
  • Cluttered background is a major obstacle in developing salient object detection and tracking system for mobile device captured natural scene video frames. In this paper we propose a context aware feature vector selection model to provide an efficient noise filtering by machine learning based classifiers. Since the context awareness for feature selection is achieved by searching nearest neighborhoods, known as NP hard problem, we apply a fast approximation method with complexity analysis in details. Separability enhancement in feature vector space by adding the context aware feature subsets is studied rigorously using principal component analysis (PCA). Overall performance enhancement is quantified by the statistical measures in terms of the various machine learning models including MLP, SVM, Naïve Bayesian, CART. Summary of computational costs and performance enhancement is also presented.

Relationship between Hip Shape and Pattern Using 3D Body Model (3차원 인체모델을 이용한 엉덩이의 형태적 특징과 패턴과의 관계)

  • Cho, Young-Sook
    • Journal of the Korean Society of Clothing and Textiles
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    • v.33 no.2
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    • pp.266-275
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    • 2009
  • Variations of individual hip shapes are a major obstacle in pattern making for fitness. The drafting method is used for pattern making in today's apparel industry. Whilst catering to a limited number of information such as waist and hip sizes, this method does not cater to variations in hip shape. This paper describes the analysis of hip shapes using 3D body model and tries to make sure the relationship between hip shape and pattern by calculating hip angle and dart amount. We achieved results in analyzing various hip shapes by extracting hip angle. Moreover, various hip shapes can be divided into three types(A, B and C) by the hip angle value(KshKwshKshKwsh). When we use computerized draping method to make a personalized pattern for a tigth skirt, we easily create complex dart lines automatically. Therefore we achieve the result of individual dart amount such as distance between dart lines and dart areas. C type of hip shape had short dart length, long distance between dart lines and a large amount of dart area. On the other hand, A type had long dart length, short distance between dart lines and small amount of dart area. B type had long length and long distance between dart lines and large amount of dart area. In traditional pattern making, distance between dart lines is usually proportional to amount of dart area because of similarity in dart line shape. In our pattern, there is no proportional relationship between dart line distance and dart area. This means that variations in hip shapes result in a wide variety of dart line curvature resulting in a wide range of dart area. By ensuring an accurate relationship between hip shape and pattern, it is possible to make patterns which result in clothing that not only fits well, but also exhibits other desirable properties.

Implementation of Infant Learning Content using Augmented Reality (증강현실을 이용한 유아용 학습 콘텐츠의 구현)

  • Lee, Jong-Hyeok;Cho, Hyun-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.1
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    • pp.257-263
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    • 2011
  • Recently as AR(Augmented Reality) is focus of attention, AR is applied to various fields and is expected its valuable use. In this paper, we implemented the system based on Goblin XNA which supports high resolution model file and higher AR. We confirmed the relation of model output among the number of marker, the location and changes of camera distance. And we produced the infantile studying contents using AR and embodied. In implemented contents, we showed the familiar character to infants on each page marker. As the result of it, we can raise their concentration and at a time studying supporters can use the contents easily as well. Also we put 3 marker on each page of contents to recognize it smoothly in case one part of it is hidden by any obstacle. Finally we maximized the learning effect such as presence and immersion in studying through reinforcing 3D models according to the every situation.

Numerical Study of Unsteady Supersonic Flow Behind a Rearward-Facing Step with Slot Injection (측면제트분사가 있는 후향계단 후류의 비정상초음속유동에 대한 수치적 연구)

  • Kim,Jong-Rok;Kim,Jae-Su
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.1
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    • pp.97-103
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    • 2003
  • Numerical research has been done for the transverse jet behind a rearward-facings step in turbulent supersonic flow without chemical reaction. Purpose of transverse jet is to enhance mixing of the fuel in the combustor. Two-dimensional unsteady flowfields generated by slot injection into supersonic flow are numerically simulated with the Navier-Stokes equations with two-equation k-εε turbulence model. Numerical method is used high-order upwind TVD scheme. Eight cases are computed for different slot momentum flux ratios and slot position at downstream of the step. The flow is very similar to the cavity flow, because the jet acts as an obstacle. The numerical results thus show the periodic phenomenon.

Analysis of Breakdown Voltages of Double Gate MOSFET Using 2D Potential Model (이차원 전위분포모델을 이용한 이중게이트 MOSFET의 항복전압 분석)

  • Jung, Hakkee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.5
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    • pp.1196-1202
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    • 2013
  • This paper have analyzed the change of breakdown voltage for channel doping concentration and device parameters of double gate(DG) MOSFET using two dimensional potential model. The low breakdown voltage becomes the obstacle of power device operation, and breakdown voltage decreases seriously by the short channel effects derived from scaled down device in the case of DGMOSFET. The two dimensional analytical potential distribution derived from Poisson's equation have been used to analyze the breakdown voltage for device parameters such as channel length, channel thickness, gate oxide thickness and channel doping concentration. Resultly, we could observe the breakdown voltage has greatly influenced on device dimensional parameters as well as channel doping concentration, especially the shape of Gaussian function used as channel doping concentration.

Groundwater flow Analysis Using MODFLOW in the Tunnel (MODFLOW를 이용한 터널의 지하수 유동해석)

  • Hue, Chang-Hwan
    • Journal of Korea Water Resources Association
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    • v.36 no.1
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    • pp.129-142
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    • 2003
  • In this study, the conduct of underground water flow system with 3 dimensions is interpreted in order to examine closely the actual condition regarding the flow of the underground water which is forecast from the tunnel segment and the interpretation result which selects the design and the construction technique of the tunnel segment was applied. Also, an obstacle to construct that relates with the underground water flow in construction duration in advance will be able to apply with information that is necessary in order to establish the countermeasure. The objective tunnel is the BEOPGI tunnel segment that is 2 parallel tunnels that are a one-way 2 lane and the parameters of the MODFLOW model executing the boring investigation and the permeability examination were presumed. The underground water flow of the excavation tunnel inside was interpreted by the MODFLOW model using the parameters which is presumed and two values which compared with calculated value and observed value are the same almost. Also, when the underground water discharge quantify that followed in tunnel excavation tries to compare, the underground water total discharge quantity from tunnel point of start until destination was presumed as 0.0269㎥/day/m2m2.

Research on China's Farmland Transfer (중국의 농지유동에 관한 연구)

  • Li, Yinhua;Kim, Hanho
    • International Area Studies Review
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    • v.22 no.1
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    • pp.23-40
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    • 2018
  • In the 2000s, China has been pushing the issue of San-Nong as a national priority. Farmland transfer, one of the solutions to the problem of San-Nong, has grown rapidly over the past decade. Especially, as farmland transfer was promoted, the rural economy developed and the living standards of the farmers improved greatly. However, the rigidity of farmland transfer type, which focuses on Zhuan-Bao method, hinders farmers' willingness to relocate to farmland transfer and ultimately acts as an obstacle in promoting massive farmland transfer. The purpose of this paper is to analyze the determinants of farmland transfer types and farmland transfer prices in Chinese farmers. Based on the results of the analysis, the following implications are suggested. First, farmers should be instructed to farmland transfer in a Ru-Gu manner; Second, the contract period must be long; Third, it is necessary to prepare countermeasures for the farmland transfer by crops; Fourth, Educational programs should be built for the farmers of farmland transfer.

High Accuracy Indoor Location Sensing Solution based on EMA filter with Adaptive Signal Model in NLOS indoor environment (NLOS 실내 환경 하에서 측위 정확도 개선을 위한 EMA 필터 적용 적응적 신호 모델 기반 위치 센싱 솔루션)

  • Ha, Kyunguk;Cha, Myeonghun;Kim, Dongwan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.23 no.7
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    • pp.852-860
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    • 2019
  • In this paper, we proposed a new trilateration technique based on exponential moving average (EMA) filter with adaptive signal model which enhances accuracy of positioning system even if the RSSI changes randomly due to movement of obstacles or blind node in indoor environment. In the proposed scheme, three fixed transmitters sent out the signal to blind node. The transmitter decides the location of the blind node based on RSSI and it estimates the cause of RSSI fluctuation which is interference of obstacle or movement of blind node. When the path between blind node and transmitter has become NLOS path because of obstacles, the transmitter ignores the measured RSSI in NLOS path and replace estimated RSSI in LOS environment. In the other case, the transmitter updated the new RSSI to represent of movement of blind node. The proposed scheme has been verified on a ZigBee testbed and we proved the improved positioning accuracy compared to the existing indoor position system.