• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.5
• /
• pp.972-980
• /
• 2010

In this study, we introduce the design methodology of an optimized type-2 fuzzy cascade controller with the aid of hierarchical fair competition-based genetic algorithm(HFCGA) for ball & beam system. The ball & beam system consists of servo motor, beam and ball, and remains mutually connected in line in itself. The ball & beam system determines the position of ball through the control of a servo motor. Consequently the displacement change of the position of the moving ball and its ensuing change of the angle of the beam results in the change of the position angle of a servo motor. The type-2 fuzzy cascade controller scheme consists of the outer controller and the inner controller as two cascaded fuzzy controllers. In type-2 fuzzy logic controller(FLC) as the expanded type of type-1 fuzzy logic controller(FLC), we can effectively improve the control characteristic by using the footprint of uncertainty(FOU) of membership function. The control parameters(scaling factors) of each fuzzy controller using HFCGA which is a kind of parallel genetic algorithms(PGAs). HFCGA helps alleviate the premature convergence being generated in conventional genetic algorithms(GAs). We estimated controller characteristic parameters of optimized type-2 fuzzy cascade controller applied ball & beam system such as maximum overshoot, delay time, rise time, settling time and steady-state error. For a detailed comparative analysis from the viewpoint of the performance results and the design methodology, the proposed method for the ball & beam system which is realized by the fuzzy cascade controller based on HFCGA, is presented in comparison with the conventional PD cascade controller based on serial genetic algorithms.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.3
• /
• pp.322-330
• /
• 2014

New effective techniques to repair "small" design errors in integrated circuits are presented. As semiconductor chip complexity increases and the design period becomes tight, errors frequently remain in a fabricated chip making revisions required. Full mask revision significantly increases the cost and time-to-market. However, since many "small" errors can be repaired by modifying several connections among the circuit blocks and spare cells, errors can frequently be repaired by revising metal layers. Metal only revision takes significantly less time and involves less cost when compared to full mask revision, since mask revision costs multi-million dollars while metal revision costs tens of thousand dollars. In our research, new techniques are developed to further reduce the number of metal layers to be revised. Specifically, we partition the circuit blocks with higher error probabilities and extend the terminals of the signals crossing the partition boundaries to the preselected metal repair layers. Our partitioning and pin extension to repair layers can significantly improve the repairability by revising only the metal repair layers. Since pin extension may increase delay slightly, this method can be used for non-timing-critical parts of circuits. Experimental results by using academia and industrial circuits show that the revision of the two metal layers can repair many "small" errors at low-cost and with short revision time. On the average, when 11.64% of the spare cell area and 24.72% of the extended pins are added to the original circuits, 83.74% of the single errors (and 72.22% of the double errors) can be corrected by using two metal revision. We also suggest methods to use our repair techniques with normal commercial vender tools.

• Journal of Broadcast Engineering
• /
• v.16 no.5
• /
• pp.738-749
• /
• 2011

In this paper, we study QoS(Quality of Service) control protocols and the effect using MAC/PHY parameters of client device in mobile network. We proposes the way of controling the bit-rate by estimating the channel condition of the client with measured MAC/PHY parameters which is sent from the client. With the proposed method, more accurate available bit-rate can be estimated compared to conventional protocol, RTCP(Real-time Transport Control Protocol). The accurate bit-rate estimation can decrease wasted bit-rate and transport delay. In the result of the advantages, the transported video quality can be enhanced. In this paper, we show the effects of enhancement using client's the field data measured in WiMAX.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.1
• /
• pp.89-96
• /
• 2016

TDOA(time delay of arrival) position estimate from acoustic measurement of artillery shell impact is studied in order to develop a targeting evaluation system. Impact position is calculated from the intersections of hyperbolic estimates based on the least square Taylor series method. The mathematical process of Taylor series estimation is known to be robust. However, the concern lays with the accuracy because it is sensitive to the bias caused by the randomness of measurement situation. The measurement error typically occurs from the distortion of waveform, change of travelling path, and sensor position error. For outdoor measurement, a consideration should be made on the atmospheric condition such as temperature and wind which can possibly change the trajectories of rays of sound. It produces wrong propagation time events accordingly. Ray tracing and optimization techniques are introduced in this study to minimize the bias induced by the ray of sound. The numerical simulation shows that the atmospheric correction improves the estimation accuracy.

• Journal of Korean Academy of Nursing Administration
• /
• v.17 no.1
• /
• pp.66-73
• /
• 2011

Purpose: The purpose of this study was to demonstrate effects of a critical pathway (CP) for stroke patients seen in emergency rooms (ER). Method: The CP developed by the CP committee consisted of 8 criteria: behavior of doctors and nurses, laboratory tests, Image testing, medication, treatment, activity, and nutrition. According to application of CP, a control group (n=17) and experimental group (n=17) were defined. Time was checked by the electronic medical records. Result: Use of CP for stroke patients in the ER, resulted in a decreased length of stay in ER (t=2.341, p=.026), and time required for image testing (t=2.623, p=.021), and an increased number of patients using rtPA ($x^2$=4.802, p=.049). Time required for neurology doctor contact, for neurology doctor to see patient in the ER, and for report of blood tests decreased, but there were no statistical significance. Conclusion: Quick responses are most important in the ER, so CP for these patients is a very effective patient management tool. To reduce delay in stroke diagnosis, continuous education programs for similar symptoms are necessary. CPs for other patients in the ER should be developed, and studies on cost and satisfaction, as well as length of stay, should be done.

• Journal of the Korean Society for Railway
• /
• v.17 no.4
• /
• pp.313-319
• /
• 2014

Additional train scheduling is often required to increase the capacity of transporting passengers or freight. In most previous studies on scheduling additional trains, operation time of the added train is designated first; and then the train operation feasibility is examined. However, it is often difficult to apply this approach to domestic trains because the density of the railroad network in Korea is high and various types of trains are in use. Moreover, for freight trains, it is even more challenging because the delay is accumulated due to lower priority whenever a freight train and a passenger train contend for a common segment of rail. In this paper, we address the additional train scheduling problem which entails finding a feasible schedule for an additional train having a fixed departure time or departure time windows. The problem is modeled as a mixed integer programming and a column generation technique is used to solve it.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.10
• /
• pp.1210-1220
• /
• 2016

As modern warfare has changed into network centered, the ability to share situational awareness among allies become a core competency for performing operational missions. In an airborne environment, it uses a tactical data link such as Link-16 for shared situational awareness. There exist problems when it shares situational awareness over the existing data link that can not allocate slots dynamically or that can not change the number of a slot to be allocated. In addition, there was a problem that can not share this failure so that failed to improves situation awareness because of finite time slot resources. In this paper, we accommodate dynamic slot allocation and changes of slot allocation with mixed structure of TDMA (time division multiple access) and random access. We propose a technique that can be used when available slots are exhausted, and a load balancing method to prevent slot allocation delay when slot requesting or message sending is concentrated on a single subframe.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.10
• /
• pp.2485-2492
• /
• 1997

Nowadays the traffic conditions have been getting worse due to continuous increase in the number of vehicles. So it has become more important to manage traffic signal lights efficiently. Recently fuzzy logic is introduced to control the cycle time of traffic lights adaptively. Conventional fuzzy logic controller adjusts the extension time of current green phase by using the fuzzy input variables such as the number of entering vehicles at the green light and the number of waiting vehicle during the red light. However this scheme is inadequate for an intersection with variable traffic densities. In this paper, a new FLC with asymmetric membership functions that reflects more exactly traffic flows than other FLCs with symmetric ones regardless of few control rules is propsed. The effectiveness of the proposed method was shown through simulation of a single intersection. The experimental results yielded the superior performance of the proposed FLC in terms of the average delay time, the number of passed vehicles, and the degree of saturation.

• Tunnel and Underground Space
• /
• v.15 no.3 s.56
• /
• pp.177-184
• /
• 2005

The Sapaesan tunnel, the longest twin tube tunnel (4km) in Korea with 4 lanes each, is under construction with two years of delayed schedule because of the strong opposition from environmental bodies. Therefore, maximizing the construction efficiency was needed in tunnel project to compensate for time delay. This study includes improvements in the construction of the Sapaesan tunnel such as increasing excavation length and changing excavation sequence. In this paper the system for predicting tunnel face ahead is also introduced. Bulk-Emulsion explosive and Cylinder-Cut method were adopted in tunnel blasting to increase the excavation length. Optimum tunnel excavation step was designed to make up delayed time. Tunnel foe mapping, TSP survey and geological prediction system using computerized jumbo-drill were performed fnr safe construction of long and large twin tube tunnel.

• Journal of Korea Multimedia Society
• /
• v.11 no.7
• /
• pp.1025-1034
• /
• 2008

In this paper, we developed GridGML for efficiently supplying a GML and visualizing the map with partitioning map and caching method to a mobile device. In order to overcome the weighting of a file, which is the biggest weakness of a GML, GridGML extracts only the most necessary parts for the visualization of the map among GML attributes, and makes the file light as a class instance by applying an offset value. GridGML manages a partition based on the visualization area of a mobile device to visualize the map to a mobile device in real time, and transmits the partition area by serializing it for the benefit of transmission. Also, the received partition area is compounded in a mobile device and is visualized by being partitioned again as four visible areas based on the display of a mobile device. Then, the area is managed by applying a caching algorithm in consideration of repetitiveness for a received map for the efficient operation of resources. Also, in order to prevent the delay in transmission time as regards the instance density area of the map, an adaptive map partition mechanism is proposed for maintaining the transmission time uniformly.