• 한국지구물리탐사학회:학술대회논문집
• /
• 2009.10a
• /
• pp.198-202
• /
• 2009

Split Hopkinson pressure bar(SHPB) is used to obtain compressive stress-strain data and deformation characteristics of brittle materials such as rock and concrete. SHPB demands both dynamic stress equilibrium condition and nearly constant strain rate before the failure of the specimen. Pulse shape technique, which places a thin metal disk between launched impact bar and incident bar, should be adopted to satisfy both conditions. In this study, metallic disks with various shapes were used to control the incident impact wave. The results show that the peak value of stress and the length of waves increased with decreasing thickness and diameter of the pulse shaper. In order to investigate shape and strain rate-dependency of the pulse shapers, dynamic compressive stress-strain curves were obtained and analyzed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.666-668
• /
• 2011

Last QoS / QoE technology as part of the HTTP-based adaptive streaming technology has attracted attention. In this paper, HTTP-based adaptive streaming technology Find out about the dynamic. It is based on a dynamic adaptive streaming system over HTTP was designed and implemented. The system converts by the bit rate of MPEG2-TS files, Segment Split, MPD (Media Presentation Description) between servers and clients with the creation of a dynamic and adaptive analysis of network environments over MPD File consists bitrate's player. This diverse network environments, continuous and smooth playback of video will be used in various multimedia fields.

• Korean Journal of Metals and Materials
• /
• v.48 no.6
• /
• pp.477-488
• /
• 2010

Zr-based amorphous alloy matrix composites reinforced with stainless steel (STS) and tantalum continuous fibers were fabricated without pores or defects by a liquid pressing process, and their quasi-static and dynamic deformation behaviors were investigated by using a universal testing machine and a Split Hopkinson pressure bar, respectively. The quasi-static compressive test results indicated that the fiberreinforced composites showed amaximum strength of about 1050~1300 MPa, and its strength maintained over 700 MPa until reaching astrain of 40%. Under dynamic loading, the maximum stresses of the composites were considerably higher than those under quasi-static loading because of the strain-rate hardening effect, whereas the fracture strains were considerably lower than those under quasi-static loading because of the decreased resistance to fracture. The STS-fiber-reinforced composite showed a greater compressive strength and ductility under dynamic loading than the tantalum-fiber-reinforced composite because of the excellent resistance to fracture of STS fibers.

• Steel and Composite Structures
• /
• v.16 no.2
• /
• pp.135-156
• /
• 2014

In this research the effect of seismic design level as a practical approach for progressive collapse mitigation and reaching desired structural safety against it in seismically designed concentric braced frame buildings was investigated. It was achieved by performing preliminary and advanced progressive collapse analysis of several split-X braced frame buildings, designed for each seismic zone according to UBC 97 and by applying various Seismic Load Factors (SLFs). The outer frames of such structures were studied for collapse progression while losing one column and connected brace in the first story. Preliminary analysis results showed the necessity of performing advanced element loss analysis, consisting of Vertical Incremental Dynamic Analysis (VIDA) and Performance-Based Analysis (PBA), in order to compute the progressive collapse safety of the structures while increasing SLF for each seismic zone. In addition, by sensitivity analysis it became possible to introduce the equation of structural safety against progressive collapse for concentrically braced frames as a function of SLF for each seismic zone. Finally, the equation of progressive collapse safety as a function of bracing member capacity was presented.

• International Journal of Automotive Technology
• /
• v.3 no.2
• /
• pp.63-70
• /
• 2002

Future on-board vehicle control systems can be further improved through new types of mechatronic systems. In particular, these systems' capacities for interaction enhance safety, comfort and economic viability. The Automotive Engineering Department (fzd) of darmstadt University of Technology is engaged in research of the mechatronic vehicle corner, which consists of three subsystems: sensor tire, electrically actuated wheel brake and smart suspension. By intercommunication of these three systems, the brake controller receives direct, fast and permanent information about dynamic events in the tire contact area provided by the tire sensor as valuable control input. This allows to control operation conditions of each wheel brake. The information provided by the tire sensor for example help to distinguish between staightline driving and cornering as well as to determine $\mu$-split conditions. In conjunction with current information of dynamic wheel loads, tire pressures and friction tyre/road, the ideal brake force distribution can be achieved. Alike through integration of adaptive suspension bushings, elastokinematic behaviour and wheel positions can be adapted to manoeuver-oriented requirements.

• Journal of radiological science and technology
• /
• v.39 no.2
• /
• pp.199-208
• /
• 2016

$^{99}mTc-MAG_3$ Renal scan is a method that acquires dynamic renal scan image by using $^{99}mTc-MAG_3$ and dynamically visualizes process of radioactive agent being absorbed to kidney and excreted continuously. Once the test starts, ratio in both kidneys in 1~2.5 minutes was measured to obtain split renal function and split renal function can be expressed in ratio based on overall renal function. This study is based on compares split renal function obtained from data acquired from posterior detector, which is a conventional renal function test method, with split renal function acquired from the geometric mean of values obtained from anterior and posterior detectors, and studies utility of attenuation compensation depending on difference in geometric mean kidney depth. From July, 2015 to February 2016, 33 patients who undertook $^{99}mTc-MAG_3$ Renal scan(13 male, 20 female, average age of 44.66 with range of 5~70, average height of 160.40cm, average weight of 55.40kg) were selected as subjects. Depth of kidney was shown to be 65.82 mm at average for left and 71.62 mm at average for right. In supine position, 30 out of 33 patients showed higher ratio of deep-situated kidney and lower ratio of shallow-situated kidney. Such result is deemed to be due to correction by attenuation between deep-situated kidney and detector and in case where there is difference between the depth of both kidneys such as, lesions in or around kidney, spine malformation, and ectopic kidney, ratio of deep-situated kidney must be compensated for more accurate calculation of split renal function, when compared to the conventional test method (posterior detector counting).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.2
• /
• pp.175-181
• /
• 2004

Analysis of brake characteristics has progressed rapidly in recent years, as computer techniques have developed. However, there are many problems in predicting braking characteristics, due to the numerous design variables of the brake system. Therefore, a synthetic braking performance analysis is required for all brake system parts such as master cylinder, booster, control valve and split system. In this paper, a program which can analyze braking performance such as force distribution, braking efficiency, pedal force and pedal travel, is presented. The preprocessor of the program helps users prepare input files through a dialog box. An additional postprocessor makes the graph presentation of solved results. Also, a simple example problem is applied to show the usefulness of the presented program.

• Journal of Aerospace System Engineering
• /
• v.1 no.3
• /
• pp.26-31
• /
• 2007

This paper addresses a method for structural optimum design of composite rotor blade. The basic model of a composite helicopter main rotor blade is designed and its parameters determining the structural/dynamic properties are studied. Through the investigation of flap/lag/torsional stiffness, the structural properties of the model are analyzed. In this study, helicopter rotor blades are analyzed by using VABS. The computer program VABS (Variational Asymptotic Beam Section Analysis) uses the variational asymptotic method to split a three-dimensional nonlinear elasticity problem into a two dimensional cross-sectional analysis and a one-dimensional nonlinear beam problem. This is accomplished by taking advantage of certain small parameters inherent to beam-like structures. In addition, the rotational stability of the blade is estimated by the frequency diagram from FE analysis(MSC.Patran/Nastran) to understand its vibrational property. From the result, design parameters to determine and optimize the properties of the model are presented.

• ETRI Journal
• /
• v.35 no.3
• /
• pp.414-424
• /
• 2013

We consider a new load balancing routing for delay-guaranteed services in the network in which the traffic is dynamic and network topologies frequently change. For such an ever-changing network, we propose a new online load balancing routing called AntLBR, which exploits the ant colony optimization method. Generally, to achieve load balancing, researchers have tried to calculate the traffic split ratio by solving a complicated linear programming (LP) problem under the static network environment. In contrast, the proposed AntLBR does not make any attempt to solve this complicated LP problem. So as to achieve load balancing, AntLBR simply forwards incoming flows by referring to the amount of pheromone trails. Simulation results indicate that the AntLBR algorithm achieves a more load-balanced network under the changing network environment than techniques used in previous research while guaranteeing the requirements of delay-guaranteed services.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.711-716
• /
• 2003

This study considers the implementation issues of the inter-vehicle communication system for the vehicle platoon experiments via a testbed. The testbed, which consists of three scale vehicles and one RCS(remote control station), is developed as a tool for functions evaluation between simulation studies and full-sized vehicle researches in the previous study. The cooperative communication of the vehicle-to-vehicle or the vehicle-to-roadside plays a key role for keeping the relative spacing of vehicles small in a vehicle platoon. The static platoon control, where the number of vehicles remains constant, is sufficient for the information to be transmitted in the suitably fixed interval, while the dynamic platoon control such as merge or split requires more flexible network architecture for the dynamical coordination of the communication sequence. In this study, the wireless communication device and the reliable protocol of the flexible network architecture are implemented for our testbed, using the low-cost, ISM band transceiver and the 8-bit microcontroller.