• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3278-3288
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• 1999

This paper proposes a security platform, called SCAP(Security platform for CORBA based APplication), to cope with potential threats in a distributed object system. SCAP supports CORBA security specification announced by OMG. SCAP is comprised of four functional blocks, which co-work with ORB to provide security services: Authentication Block, Association Block, Access Control Block, and Security Information Management Block. It is designed to support Common Secure Interoperability Functionality Level 2, which is useful for large-scale intra-, or inter-network based applications. Actual security services, which are dependent on supporting security technology, will be provided as external security service for replace ability. Implementation issues such as how to simulate an interceptor mechanism using a commercial ORB product without source code, and how to extend Current object required for security services are also described. At the end of the paper, the SCAP applied to the web environment is described to show its practical utilization.

• Journal of computational fluids engineering
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• v.12 no.3
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• pp.41-46
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• 2007

Dynamic behavior of immiscible gas bubble attached to the wall in channel flow plays very important role in many engineering applications. Special attention has been paid to micro direct methanol fuel cell(${\mu}$DMFC) where surface tension becomes dominant factor with minor gravitational effect due to its reduced size. Therefore, displacement of $CO_2$ bubble generating on a cathode side in ${\mu}$DMFC can be very difficult and efficient removal of $CO_2$ bubbles will affect the overall machine performance considerably. We have focused our efforts on studying the dynamic behavior of immiscible bubble attached to the one side of the wall on 2D rectangular channel subject to external shear flow. We used Level Contour Reconstruction Method(LCRM) which is the simplified version of front tracking method to track the bubble interface motion. Effects of Reynolds number, Weber number, advancing/receding contact angle and property ratio on bubble detachment characteristic has been numerically identified.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.72-81
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• 1999

A nonlinear engine torque and speed control algorithm using throttle angle control is developed with an engine load torque estimation algorithm. Three 3-dimensional nonlinear engine maps as a part of the nonlinear control algorithm are obtained from steady state engine dynamometer tests. An electric throttle actuator is developed using a stepper motor and a 8 bit micro-processor. The speed control and external load estimation algorithm are tested via engine speed control experiments, and show performance good enough for using various engine torque and speed control applications.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.25-30
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• 2000

The object of this work is to develop an assessment system for pipeline integrity The system consists of four module applications for internal algorithm; the effect of corrosion in pipeline, crack, stress corrosion crack (SCC) and fatigue modules. Presently, the module of the external corrosion has been developed and the internal algorithm for the effect of corrosion in pipeline and the database of the system are described in this paper, The database of the system is separated to mainly four parts; geometry of pipeline, material properties, boundary conditions and general Properties. Each components of the system are designed by user-friendly concept. This system may give a guideline for maintenance and modifications for the pipeline at the industrial sight. Furthermore, a procedure to evaluate an inspection interval is also provided.

• Smart Structures and Systems
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• v.13 no.3
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• pp.343-352
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• 2014

Given a body undergoing a stress-strain status as consequence of external excitations, sensors can be deployed on the accessible lateral surface of the body. The sensor readings are regarded as input of a numerical model of reduced order (i.e., the number of sensors is lower than the number of the state variables the full model would require). The goal is to locate the sensors in such a way to minimize the deviations from the response of the true (full) model. One adopts either accelerometers as sensors or devices reading relative displacements. Two applications are studied: a plane frame is first investigated; the focus is eventually on a 3D body.

• Journal of the Korean Institute of Rural Architecture
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• v.14 no.1
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• pp.75-82
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• 2012

Today, educational facilities are considered to be one of the most important built environment. And the appropriate combinations and applications of technical elements related to green building on the education facilities are emphasized and demanded. These are must be compatible with the occupants' activities and their needs. The objective of this research is to identify and analyze of green building technologies, based on Green Educational Facilities' Case Study in Korea, USA, and Japan. As a result of the comparative analysis of this research, the green technological approaches, problem, and characteristics on educational facilities in different area, climate zone are identified and analyzed by external environment, energy, materials and resources, and indoor environment. It is useful as basic reference for future green educational facilities' planning and design in Korea.

• Journal of information and communication convergence engineering
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• v.6 no.2
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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.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.738-741
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• 2004

The overall performance of AC servo system is greatly affected by the uncertainties of unpredictable mechanical parameter variations and external load disturbances. Therefore, to compensate this problem, it is necessary to know different parameters and load disturbances subjected to position/speed control. This paper proposes an online identification method of mechanical parameters/load disturbances for AC servo system using Support Vector Regression (SVR). The proposed methodology advocates analytic parameter regression directly from the training data, rather than adaptive controller and observer approaches commonly used in motion control applications. The experimental results demonstrate that the proposed SVR algorithm is appropriate for control of unknown servo systems even with large measurement noise.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.778-780
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• 2000

The 74181 is arithmetic logic units(ALU)/function generator. This circuit performs 16 binary arithmetic operations on two 4-bit words. And a full carry look-ahead scheme is made available in this device. The 74181 can also be utilized as a comparator. This circuit has been also designed to provide 16 possible functions of two Boolean variables without the use of external circuitry. This paper analyzes the function of the logic and the implementation adopted in the design of 74181. The understanding of the logic characteristics of this chip enables us to improve future applications.

• Transactions of Materials Processing
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• v.15 no.4 s.85
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• pp.319-325
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• 2006

The laser forming process is a new flexible forming process without forming tools and external force, which is applied to various fields of industry. Especially, applications of the laser forming process focused on cutting, welding and marking process. In this paper, the laser bending process of sheet metal which is heated by laser beam and formed by internal stress is simulated by using thermo elastic-plastic analysis model. Based on the result of FE-analysis, the laser bending machine is made to obtain reliable data for sheet bending. Under the same condition as FE-analysis, the laser bending experiment has been performed to ver 펴 the result of FE-analysis and good agreement has been obtained between FE-analysis and experiments. Additional laser bending experiments have been performed to evaluate the laser bending machine.