• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.197-198
• /
• 2023

This study was conducted as part of research and development of high-strength grout. Accordingly, dolomite aggregate was used as a filler incorporated into the high-strength grout. Dolomite aggregate has a disadvantage of increasing the viscosity of the grout due to higher generation of fine powder than other aggregates. Accordingly, in this experiment, it was confirmed that the viscosity, flow time, and flow of high-strength grout change according to the volume composition ratio of dolomite aggregate and cement-based material. All experiments were conducted based on the Korean Industrial Standard KS F 4044, and the mixing factor was applied according to the composition ratio of the binder and the filler. In the experiment, the amount of fine powder contained in the dolomite aggregate rather than the silica sand used in the past is grasped, and after mixing with the grout accordingly, the mixture is proceeded to measure the viscosity in an unhardened state. In addition, the flow and flow time of the grout are evaluated according to the viscosity. As a result of the experiment, it was confirmed that the viscosity and flow time decreased and the flow increased as the volume composition ratio of the dolomite aggregate to the cement-based material increased.

• ETRI Journal
• /
• v.30 no.2
• /
• pp.238-248
• /
• 2008

At the extremes of the complexity-performance plane, there are two exemplary QoS management architectures: Integrated Services (IntServ) and Differentiated Services (DiffServ). IntServ performs ideally but is not scalable. DiffServ is simple enough to be adopted in today' core networks, but without any performance guarantee. Many compromise solutions have been proposed. These schemes, called quasi-stateful IntServ or stateful DiffServ, however, have not attracted much attention due to their inherently compromising natures. Two disruptive flow-based architectures have been recently introduced: the flow-aware network (FAN) and the flow-state-aware network (FSA). FAN's control is implicit without any signaling. FSA's control is even more sophisticated than that of IntServ. In this paper, we survey established QoS architectures, review disruptive architectures, discuss their rationales, and points out their disadvantages. A new QoS management architecture, flow-aggregate-based services (FAbS), is then proposed. The FAbS architecture has two novel building blocks: inter-domain flow aggregation and endpoint implicit admission control.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.11 no.5
• /
• pp.277-285
• /
• 2016

Moving object detection system has been an emerging research field in various advanced driver assistance systems (ADAS) and surveillance system. In this paper, we propose two optical flow based moving object detection methods at dynamic scenes. Both proposed methods consist of three successive steps; pre-processing, foreground segmentation, and post-processing steps. Two proposed methods have the same pre-processing and post-processing steps, but different foreground segmentation step. Pre-processing calculates mainly optical flow map of which each pixel has the amplitude of motion vector. Dense optical flows are estimated by using Farneback technique, and the amplitude of the motion normalized into the range from 0 to 255 is assigned to each pixel of optical flow map. In the foreground segmentation step, moving object and background are classified by using the optical flow map. Here, we proposed two algorithms. One is Gaussian mixture model (GMM) based background subtraction, which is applied on optical map. Another is adaptive thresholding based foreground segmentation, which classifies each pixel into object and background by updating threshold value column by column. Through the simulations, we show that both optical flow based methods can achieve good enough object detection performances in dynamic scenes.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.19-23
• /
• 2003

This paper presents a new concept of reactive reserve based contingency constrained optimal power flow (RCCOPF) for voltage stability enhancement. This concept is based on the fact that increase in reactive reserves is effective for enhancement of voltage stability margins of post-contingent states, in this paper, the proposed algorithm is applied to voltage stability margin of interface flow. Interface flow limit, in the open access environment, can be a main drawback. RCCOPF for enhancement of interface flow margin is composed of two modules, modified continuation power flow (MCPF) and optimal power flow (OPF). These modules art recursively perform ed until satisfying the required margin of interface flow in the given voltage stability criteria.

• Journal of the Semiconductor & Display Technology
• /
• v.7 no.2
• /
• pp.55-58
• /
• 2008

The objective of the research is to design, manufacture and test a Mass Flow Controller(MFC) capable of measuring compressible fluid flows based on a "bucket and stop-watch"method. The basic principle is the measurement of time, where the time taken to fill and empty a bucket of known volume is measured. This method of flow measurement is a new concept when compared to a commercilized current mass flow controller. For the flow meter to be able to compete with established designs it not only must be comparable in cost and robustness, it must be very accurate and reliable as well. This device should be able to handle fluid flows in the range of 0.1ml/min to 10ml/min within an accuracy of ${\pm}$1%. A possible application for a device such as this is in electronics industry where arsenic gas is used in the production of silicon chips.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.38 no.1
• /
• pp.45-52
• /
• 2001

The proximal isovelocity surface area (PISA) method is an effective way of measuring the regurgitant blood flow rate in the mitral valve. This method defines the modelling required to describe the geometry of the isotach of the PISA. In the normal PISA flow model, the flow rate is calculated assuming that the surface of the isotach is either hemispherical or non-hemispherical numerically. However, this paper evaluated the estimate flow rate using a direct surface subdivision flow model based on the height field after isotach extraction using a region-based scheme. To validate the proposed method, the various PISA flow models were compared using pusatile color Doppler images with flow rates ranging from $30\;cm^3/sec\;to\;60\;cm^3/sec$ flow rate. Whereas the hemispherical flow model had a mean value of $29\;cm^3/sec$ and underestimated the measured flow rate by 35%, the proposed model and non-hemispherical model produced a c;ame mean value of $45\;cm^3/sec$, moreover, both flow models produced a similar pulsatile flow rate.

• Journal of computational fluids engineering
• /
• v.15 no.1
• /
• pp.88-94
• /
• 2010

In general, flow analysis programs have been built in not JAVA language but such as Fortran, C or C++ because of a merit in performance of computation. However, most developer of those languages are not free for use. User should purchase the development tools of programs, and install it on their own computer. Fortunately, JAVA is a free software, and can be used to develop WEB-based programs. It is well known that the JAVA language is time consuming for calculating. However, the performance of computer power has been increased continuously, so it is sure that the former states can be overcome. In the present study, a flow analysis program, which is interactive with Graphics, using the Web-based programing language, JAVA, has been developed for solving the two-dimensional flow motion.

• Advances in aircraft and spacecraft science
• /
• v.8 no.4
• /
• pp.273-287
• /
• 2021

Model-based, data-driven and physics-based approaches represent the state-of-the-art techniques to estimate the aircraft flow angles, angle-of-attack and angle-of-sideslip, in avionics. Thanks to sensor fusion techniques, a synthetic sensor is able to provide estimation of flow angles without any dedicated physical sensors. The work deals with a physics-based scheme derived from flight mechanic theory that leads to a nonlinear flow angle model. Even though several solvers can be adopted, nonlinear models can be replaced with less accurate but straightforward ones in practical applications. The present work proposes a linearisation to obtain the flow angles' closed form solution that is verified using a flight simulator. The main objective of the paper, in fact, is to analyse the estimation degradation using the proposed closed form solutions with respect to the nonlinear scheme. Moreover, flight conditions, where the proposed closed form solutions are not applicable, are identified.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.1
• /
• pp.49-55
• /
• 2010

This study describes a development of GIS-based program called Debris Flow Analyzer for simulating the hazard extent of debris flow on the assumption that is uniform continuous, incompressible, unsteady. The Debris Flow Analyzer was designed to process debris flow numerical simulation with Finite Difference Formulation; smoothed DEM, slope, debris flow directions, extract valley, debris volume, water volume, debris flow moving speed, effective viscosity, dynamic friction coefficient. Also, it is expected that we can be improved the inform of debris flow hazard map by Google Earth.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.13 no.5
• /
• pp.225-234
• /
• 2018

Control flow errors are caused by the vulnerability of memory and result in system failure. Signature-based control flow monitoring is a representative method for alleviating the problem. The method commonly consists of two routines; one routine is signature update and the other is signature verification. However, in the existing signature-based control flow monitoring, monitoring target application is tightly combined with the monitoring code, and the operation of monitoring in a single thread is the basic model. This makes the signature-based monitoring method difficult to expect performance improvement that can be taken in multi-thread and multi-core environments. In this paper, we propose a new signature-based control flow monitoring model that separates signature update and signature verification in thread level. The signature update is combined with application thread and signature verification runs on a separate monitor thread. In the proposed model, the application thread and the monitor thread are separated from each other, so that we can expect a performance improvement that can be taken in a multi-core and multi-thread environment.