• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.519-522
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• 2002

An active phased array antenna consists of many channels. Each channel has a different initial phase shift and gain because of the inequality in the active circuits themselves, interface between radiators and active circuits, and beam-forming circuits and other antenna system configurations. This raises an inherent problem in active phased array antennas. To compensate for this problem the initial phase and gain of each channel should be calibrated. This paper presents an efficient calibration method for an initial phase variation of each channel in active phased array antennas. We tested our method in an active phased array antenna, and obtained good results in the radiation pattern and beam direction of antenna.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.406-409
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• 2004

Recently, many auto makers and OEM are now developing various telematics control units(TCU). TCU has an embedded OS and many user-friendly services inherently and frequently the driver operates the TCU on driving a car. Although the TCU has some accident resistive functions, secondhand accidental problem arose. Current Korean domestic TCUs have some interfaces such as push-button, touch screen, voice recognition and etc. But, because of operational complexity, technical limitation, it has not sufficient user-friendly interface. In this paper, to overcome this problem, haptic devices are considered. We present haptic devices and applications on the basis of that of U.S. Immersion co. and also BMW's iDrive technology.

• Management & Information Systems Review
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• v.2
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• pp.169-193
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• 1998

Case- based reasoning(CBR) offers a new approach for developing knowledge based systems. Unlike the rule-based paradigm, in which domain knowledge is encoded in the form of production rules, in the case-based approach the problem solving experience of the domain expert is encoded in the form of cases stored in a casebase(CB). CBR allows a reasoner (1) to propose solutions in domains that are not completely understood by the reasoner, (2) to evaluate solutions when no algorithmic method is available for evaluation, and (3) to interprete open-ended and ill-defined concepts. CBR also helps reasoner (4) take actions to avoid repeating past mistakes, and (5) focus its reasoning on important parts of a problem. Owing to the above advantages, CBR has successfully been applied to many kinds of problems such as design, planning, diagnosis and instruction. In this paper, I propose case-based DSS(CBDSS). CBDSS is an intelligent DSS using CBR technique. CBDSS consists of interface, case-based reasoner, maintainer, casebase management system, domain dependent CB, domain independent CB, and so on.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.93-100
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• 2003

This paper describes the thermoelastic instability arising from friction heat generation in braking and proposes the finite element methods to predict the variation of temperature and thermal deformation. In a conventional disc brake analysis, heat generation is only related with wheel speed and friction material and the interface pressure between disc and pad is assumed constant. But under dynamic braking conditions, the frictional heat causes the thermoelastic distortion that leads to more concentrated contact pressure distribution and hence more and more non-uniform temperature. In this paper, to complete the solution of the thermomechanically coupled problem, the linear relation model between pressure and temperature is proposed and demonstrated in examples of a simple two dimensional contact problem. And the two dimensional model has been extended to an annular three dimensional disc model in order to consider more realistic geometry and to provide a more accurate critical speed for automotive brake systems.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.12
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• pp.1002-1010
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• 2005

We study on the implementation of reconfigurable position control system which is based on Open Control Platform(OCP) for Unmanned Expedition Vehicles(UEV) in ubiquitous environment. The control system uses hierarchical control structure and OCP structure which contains three layers such as core OCP, reconfigurable control API(Application Programmer Interface), generic hybrid control API. The goal of our research is to implement an UEV control system using advanced software technology. As a specific control problem, we study a transition management problem between PID control and neural network control depending on fault or parameter change of the plant, i.e., UEV. The concept of the OCP-based software-enabled control can provide synergy effect by the integration of software component, middleware, network communication, and control, and thus can be applied to various systems in ubiquitous environment.

• Bulletin of the Korean Mathematical Society
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• v.50 no.6
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• pp.2035-2051
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• 2013

In this paper, we study numerical schemes for solving multi-dimensional option pricing problem. We compare the direct solving method and the Operator Splitting Method(OSM) by using finite difference approximations. By varying parameters of the Black-Scholes equations for the maximum on the call option problem, we observed that there is no significant difference between the two methods on the convergence criterion except a huge difference in computation cost. Therefore, the two methods are compatible in practice and one can improve the time efficiency by combining the OSM with parallel computation technique. We show numerical examples including the Equity-Linked Security(ELS) pricing based on either two assets or three assets by using the OSM with the Monte-Carlo Simulation as the benchmark.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.1-10
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• 1997

Finding the optimum route of ship's pipes is complicated and time-consuming process. Experience of designers is the main tool in this process. To reduce design man-hours and human errors a design expert system shell and a geometric modeler is used to automate the design process. In this paper, a framework of the intelligent CAD system for pipe auto-routing is suggested, which consists of general-purpose expert system shell and a geometric modeler. The design expert system and the geometric modeling kernel have been integrated. The CADDS5 of Computervision is used as the overall CAD environment. The Nexpert Object of Neuron Data is used as the expert system shell. The CADDS5 ISSM is used as the interface that creates and modifies geometric models of pipes. Existing algorithms for the routing problem have been analyzed. Most of them are to solve the 2-D circuit routing problems. Ship piping system, specially within the engine room, is a complicated, large scale 3-D routing problem. Methods of expert system have been used to find the route of ship pipes on the main deck.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.126.4-126
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• 2001

Recently, researches on CIM in product lines of industrial plant are widely progressed, automation of working environment with modernization of product equipments is realized and also, installation of integrated control system based on computer is activated. Since the CIM system is basically developed by using computer, there are several complicated problems such as design problem of hardware interface between computer and many product machines with individual special functions, software development problem with realtime data process and multi communication functions for realtime data monitoring and control of product machines This paper shows the development results for a single board type of microcontroller and a monitoring software based on realtime processing database system ...

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.55-58
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• 2000

This paper describes a single transistor type ferroelectric field effect transistor (1T FeFET) memory celt scheme which can select one unit memory cell and program/read it. To solve the selection problem of 1T FeEET memory cell array, the row direction common well is electrically isolated from different adjacent row direction column. So, we can control voltage of common well line. By applying bias voltage to Gate and Well, respectively, we can implant IT FeEET memory cell scheme which no interface problem and can bit operation. The results of HSPICE simulations showed the successful operations of the proposed cell scheme.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.27-32
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• 1996

In this study, the boundary element method (BEM) is used to treat the homogenization of the baffle and reflector. First, the multigroup diffusion equations (MDE) within the core are solved using BEM as a source problem under the assumption that the core material is uniformly distributed. Then, the solution to MDE for the water reflector which should be extended infinite can be attained from a boundary source problem also via BEM. Finally, these two solutions are coupled through albedos of the slab-shaped baffle so that one could obtain heterogeneous interface currents and fluxes between the core and the baffle/reflector resulting in the location-dependent equivalent parameters for the baffle/reflector.