• The Journal of the Acoustical Society of Korea
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• v.15 no.1E
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• pp.70-76
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• 1996

We proposed to use shear waves instead of longitudinal waves in a STAM (scanning tomographic acoustic microscope system) in which the specimens are solid. For any specimen with a shear modulus, mode conversion will take place at the water-solid interface. Some of the energy of the insonifying longitudinal waves in the water will convert to shear wave energy within the specimen. The shear wave energy is detectable and can be used for tomographic reconstruction. The resolution limitation of STAM depends on the available angular view and the acoustic wavelength. While wave transmission in most solid specimens is limited to about 20°for longitudinal waves, we show that it is about twice that high for shear waves. Since the wavelength of the shear wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution. In order to compare the operation of a shear-wave STAM with that of the conventional longitudinal-wave STAM we have simulated tomographic reconstruction for each. Our simulation results with aluminum specimen and back-and-forth propagation algorithm showed resolution of a shear-wave STAM is better than that of a longitudinal-wave STAM.

• The Journal of Society for e-Business Studies
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• v.7 no.1
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• pp.207-223
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• 2002

The population of consumers who purchase goods through electronic commerce(EC) is increasing due In the advance of Internet. They can purchase goods freely without time and space restriction and can have variety of choices of goods. Now most of e-Catalogs rely on the simple texts or images to present information on goods. As such, there is limitation in describing goods in detail, which might not make consumers interested in those goods. To solve the problem, more advanced e-Catalogs are demanded compared with the existing ones, requiring research on the e-Catalog authoring techniques that utilize dynamic multimedia data such as audios or videos in addition to the conventional texts and images. In this paper, we describe development of an e-Catalog authoring tnol that is based on SMIL(Synchronized Multimedia Integration Language) which is one of XML applications.

• The Journal of Society for e-Business Studies
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• v.5 no.1
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• pp.39-54
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• 2000

The importance of EDI has been so emphasized that we need exchange/maintain electronic documents effectively, and convert them to other formats. The traditional EDI, however, is facing on the limitation of growth because of its high expense, and the closeness of information sharing. The EDIs of next generation, like open EDI, object-oriented EDI, and Internet EDI, have appeared to solve these problems. Finally, XML/EDI, which is very effective to solve these kinds of problems, is now replacing the traditional EDI and the HTML in Internet and, is influencing on e-Business. So, we are going to suggest a solution which uses XML/EDI as a substitute for the traditional one. First, we analyzed the problems of the traditional EDI system and organized the structure of XML/EDI system, Next, we developed the prototype of Internet bookstore to show the effectiveness and strength of XML/EDI over the traditional EDI.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.3
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• pp.135-141
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• 2016

Indoor zone-based services have continuously become popular by increased prevalence of smartphones. Bluetooth and ultrasound can be used for zone detection. However, bluetooth does not guarantee precise zone detection if the signal degrades due to the obstacles. Ultrasound can be easily forged by recording sound on the smartphone. For that reason, zone detection based on ultrasound has a security hole. To remedy each limitation, we propose an advanced zone detection method, that combines bluetooth and ultrasound. An authentication server issues a one-time password to the user over bluetooth. The user generates an ultrasound signal that encodes the password. In this manner, the proposed method ensures secure and accurate zone detection.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.76-81
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• 2009

The transmitting node in WSN for ITS would be small and operated by battery, and the MCU in the node would be low speed with small sized memory and low power consumption. In this paper, the post-checksum method in which the checksum field is added to the tail of the TCP segment for ITS applications, is proposed to reduce data processing time and power consumption, and so there is no limitation of the transmitting data size.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.664-669
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• 1992

In this paper, we present a DSP-based high dynamic performance torque control scheme of variable reluctance motors(VRM's) for DD(Direct Drive) robots via function inversion technique. The VRM with our controller behaves like DC motors, and hence developed torque tracks given torque command accurately with no torque ripples. Furthermore, our torque control algorithm ensures the production of maximum constant torque under maximum current limitation, minimizes power loss in each phase resistance, and takes magnetic saturation effect into account. Also, since our control algorithm is represented in the form of look-up table, it can be easily implemented with simple digital circuits and this tabular design method is computationally more accurate and simpler compared to the prior methods.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.714-717
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• 1992

An intelligent robot control system is developed, which is based on extensible hardwares and softwares. The system could be used to test advanced and complex real time application programs to avoid constraints on present robot control system in executing a complex or precise algorithms, due to the limitation of hardware and software. In this paper we used the RCCL(Robot Control C Library) on SUN4 as a supervisory system that plays the path planning and man-machine interface. And we used VxWORKS as a real time OS on a VME bus CPU equiped with some interface boards. Two systems were connected through the Ethernet network. We used the 4 axis manipulator, FARA, developed by Samsung Electronics Co.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.100-105
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• 1992

A mathematical model is developed for a CSTR in which free radical solution polymerization of methyl methacrylate(MMA) takes place. It turns out that five ordinary differential equations are to be treated simultaneously in order to predict the reactor performance. Although the reaction proceeds under the conditions of relatively low temperature and pressure, the system shows very complex bifurcation features due to the diffusion limitation (gel effect) and the temperature dependence of the kinetic parameters and physical properties. The effects of various system parameters on the reactor performance as well as on the polymer properties are investigated by using the bifurcation analysis. The application of the singularity theory enables us to divide the parameter space into several different regions, in each of which the system takes a unique steady state structure. Under certain circumstances, complex dynamic features such as HB points and limit cycles are observed and these should be taken into consideration in the reactor design.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.285-289
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• 1992

This paper describes a new optimization technique for the design of traffic signal patterns. The proposed method uses a Genetic Algorithm for searching through the better signal patterns. Since the Genetic Algorithm is effective to search directly through a huge binary coded state spaces, the proposed design method has the following advantages over the conventional OR methods: (1) on-line optimization is available within a reasonable time, (2) there is no limitation to the types of signals to be optimized. Some computer simulations are carried out and its ability of getting high quality control in a short period is demonstrated.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.3
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• pp.165-173
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• 1996

It is not desirable to have too large control input in control systems, because there are usually a limitation for the input magnitude and cost for the input energy. Previous papers in the iterative learning control did not considered on these points. In this paper, an iterative learning control method is proposed for a class of nonlinear systems with consideration on input magnitude by adopting a concept of cost function consisting of the output error and the input magnitude in quadratic form. We proposed a new input update law with an input penalty function. If we choose a reasonable input penalty function, the two control objectives, good command following and small input energy, can be achieved. The characteristics of the proposed method are shown in the simulation examples.