• 산업공학
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• 제12권4호
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• pp.557-566
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• 1999

This paper considers a door-to-door service system in which pickups or deliveries are performed by a trip of a single vehicle. Each customer request specifies the quantity of the load transported, the location, and the time window within which it is to be picked up or delivered. Since the system is demand responsive, i.e., new or emergent requests become available in real-time, the current vehicle route has to be reconstructed to include these requests. In this case, only continuous vehicle tracking enables control over the requests and ensures that the requests are satisfied on time. This paper suggests a pilot pickup/delivery management system integrating a geographic information system(GIS) and a global position system(GPS) to efficiently deal with such a dynamic environment. The GIS offers a way of displaying the vehicle route on digital maps for the region under concerned. Also displayed is the current location of the vehicle obtained from the GPS. A heuristic algorithm is used to dynamically determine the vehicle route. A practical example is provided to show the feasibility of the system.

• Journal of information and communication convergence engineering
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• 제6권2호
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• pp.228-232
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• 2008

In recent years, wireless ad hoc networks have become increasingly popular in both military and civilian applications due to their capability of building networks without the need for a pre-existing infrastructure. Recently, IEEE 802.11 Task Group e has been working on a new mechanism, the Enhanced Distributed Coordination Function (EDCF), to enhance the performance of 802.11 DCF. However, EDCF only reduces the internal collisions within a station, and external collisions between stations remain high in ad-hoc networks. In this paper, we propose to adopt an adaptive backoff window control technique, based on a dynamic value of the initial value of the range in which the backoff is chosen, so the backoff timer is randomly chosen in the range (InitRng, CW-1). We use ns-2 simulation to evaluate the throughput of our scheme. Results show that the throughput is improved for our scheme compared to the original DCF due to the reduced the number of collisions.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2007년도 춘계학술발표대회
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• pp.1288-1290
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• 2007

Congestion in WSN increases energy dissipation rates of sensor nodes as well as loss of packets and thereby hinders fair and reliable event detections. We find that one of the key reasons of congestion in WSN is allowing sensing nodes to transfer as many packets as possible. This is due to the use of CSMA/CA that gives opportunistic media access control. In this paper, we propose an energy efficient congestion avoidance protocol that includes source count based hierarchical and load adaptive medium access control. Our proposed mechanism ensures load adaptive media access to the nodes and thus achieves fairness in event detection. The results of simulation show our scheme exhibits more than 90% delivery ratio with retry limit 1, even under bursty traffic condition which is good enough for reliable event perception.

• 미술이론과 현장
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• 제10호
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• pp.7-23
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• 2010

In this paper I examine Cesare Cattaneo and Mario Radice's Camerlata Fountain in northern Italy, focusing on the work's relation to the urban environment and its "mobility" over several decades. As I demonstrate, the design of Cattaneo and Radice's work relates to the circular layout of a traffic intersection and was intended to be viewed from the window of a moving automobile. In this way it continues a tradition, begun by the Futurists and continued by Le Corbusier, who saw the car as central to modern art and architecture. Moreover, the work relates to the concept of mobility in so far as it was in itially built in 1936 in Milan and subsequently destroyed and reconstructed during 1962 in its current location near Como. As the history of the work's conception, production and reception demonstrates, Cattaneo and Radice's work not only responds to the experience of vehicle-generated mobility in modern society but also reveals the tensions and anxieties associated with an increasingly dynamic urban environment.

• Journal of Welding and Joining
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• 제8권2호
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• pp.58-69
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• 1990

In conventional arc welding, position error of the weld torch with respect to the weld seam and variation of groove dimension are induced by inaccurate fitup and fixturing. In this study, a vision system has been developed to recognize and compensate the position error and dimensional inaccuracy. The system uses a structured laser light illuminated on the weld groove and perceived by a C.C.D camera. A new algorithm to detect the edge of the reflected laser light is introduced for real time processing. The developed system was applied to arbitarary weld paths with various types of joint in arc welding process. The experimental results show that the proposed system can detect the weld groove parameters within good accuracy and yield good tracking performance.

• 한국시뮬레이션학회논문지
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• 제9권1호
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• pp.67-81
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• 2000

In this paper, a new software package for modeling and simulating discrete-event dynamic systems is developed. The new software is a general-purpose, graphical tool based on timed Petri-nets and is developed using Visual Basic and Visual C++ for the window environment. It allows the user to graphically build a Petri-net model and enter input data for executing the Petri-net simulation model. It is equipped with a deadlock detection and recovery function as well as an automatic error check function. In addition, the software supports various enabling functions and distribution functions and provides various statistics for the performance measures of interests pertaining to the system. We expect the new software will be used in a wide number of applications including computer, communication and manufacturing systems.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.189-190
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• 1998

In this paper, we show the realtime 3D reconstruction algorithm with the sliced CT images. The preprocessing is thresholding, labeling, contouring, and extracting dominant point. we reconstruct 3D image with dominant points using dynamic matching technique. The software implemented in Visualc++ 5.0 as a window-based application program.

• 한국통신학회논문지
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• 제22권1호
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• pp.104-115
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• 1997

This paper investigates PN code acquistion algorithm and demodulation performance of the RAKE receiver in the DS/CDMA(direct sequence code division multiple access) sysytems under a multipath fading channel with multiusers. To speed up the acquisition process, PN matched filter is applied and postdetection integration technique comable withthe dynamic threshold set method is proposed. the Maximum-Likelihood algorithmin serial fashion is able to find PN code delay estimates for the RAKE branches using sliding window in a multipath fading channel. The correct acquistion probability and mean acquistion time are used as a performance measure of the system using the Monte Carlo method. The performance of the RAKEreceiver, afte the code acquisition is achieved is the CDMA systems, is also investigated for three major combining techniques.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.167-170
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• 2001

A low power pulse Doppler radar should integrate a large number of data to provide a required maximum detectable distance. Doppler filter needs a window that has good out-of-bard rejection level to maintain high dynamic range. From these facts, we can apply decimation and presumming to increase the speed of Doppler processing. This Paper investigates the efficiencies of several decimation methods and the loss of presumming. And I propose a method to increase processing speed but to maintain the maximum detectable distance.

• 전자공학회논문지B
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• 제30B권11호
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• pp.84-92
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• 1993

Calibration of Engine models is a painstaking process but very important for successful application to automotive industry problems. A combined heuristic and machine learning approach has therefore been adopted to improve the efficiency of model calibration. We developed an intelligent calibration program called ICALIB. It has been used on a daily basis for engine model applications, and has reduced the time required for model calibrations from many hours to a few minutes on average. In this paper, we describe the heuristic control strategies employed in ICALIB such as a hill-climbing search based on a state distance estimation function, incremental problem solution refinement by using a dynamic tolerance window, and calibration target parameter ordering for guiding the search. In addition, we present the application of amachine learning program called GID3*for automatic acquisition of heuristic rules for ordering target parameters.