• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.82-94
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• 2007

Wireless sensor networking technology is one of the basic infrastructures for ubiquitous environment. It enables us to gather various sensory data such as temperature, humidity, gas leakage, and speed from the remote sensor devices. To support these networking functions, IEEE WPAN working group makes standards for PHY and MAC, while ZigBee Alliance defines the standards for the network, security, and applications. The low-rate WPAN was emerged to have the characteristics of network resilience, low cost, and low power consumption. It has a broad range of applications including, but not limit to industrial control and monitoring, home automation, disaster forecast and monitoring, health care. In order to provide more intelligent and robust services, users want voice-based solutions to accommodate to low-rate WPAN. In this paper, we have evaluated voice quality of an IEEE 802.15.4 standard compliant voice node. Specifically, it includes the design of a voice node and experiments based on the prediction of voice quality using the E-model suggested by ITU-T G.107, and the network communication mechanisms considering beacon-enabled and nonbeacon-enabled networks for real-time voice communications.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.5
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• pp.423-433
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• 2016

In this paper, we consider the cybersecurity issue of ship information system (SIS) from a new perspective which is called opacity. For a SIS, its confidential information (named as "secret") may be leaked through the working behaviors of each Distributed Control Unit (DCU) from an outside observer called an "intruder" which is able to determine ship's mission state by detecting the source of each data flow from the corresponding DCUs in SIS. Therefore we proposed a dual layer mechanism to enforce opacity by activating non-essential DCU during secret mission. This mechanism is calculated by two types of insertion functions: Safety-assured insertion function ($f_{IS}$) and Admissibility-assured insertion function ($f_{IA}$). Due to different objectives, $f_{IS}$ is designed to confuse intruder by constructing a non-secret behaviors from a unsafe one, and the division of $f_{IA}$ is to polish the modified output behaviors back to normal. We define the property of "$I_2$-Enforceability" that dual layer insertion functions has the ability to enforce opacity. By a given mission map of SIS and the marked secret missions, we propose an algorithm to select $f_{IS}$ and compute its matchable $f_{IA}$ and then the DCUs which should be activated to release non-essential data flow in each step is calculable.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.15 no.26
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• pp.43-48
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• 1992

국제적으로 증가되어지고 있는 제조업분야의 경쟁으로 인하여 사업체들 간에는 경쟁적으로 이상적인 방법의 공장자동화 (Factory Automation)를 품질향상 및 생산성증가를 위한 한 방법으로 채택하고 있다. 치열해지는 경쟁력으로부터 시장을 고수하기 위해 공장자동화가 기업들 간에는 근본대책으로 설정되고 있는데, 이러한 경향은 사업체들이 보다 나은 품질의 제품을 저렴한 가격으로 소비자에게 제공하고 생산력향상을 경제적으로 달성하기 위하여 많은 액수의 비용을 투자하게끔 하고 있다. 현재 여러 종류의 공장자동화 방법이 개발되고 있고, 채택되어지고 있다. 그 중에서도 현재 많은 각광을 받고있는 분야가 유동제조시스템(Flexible Manufacturing System ; FMS)이다. 본 연구에서는 유동제조시스템을 공장자동화의 한 방법으로 채택하기 위해 필요한 기본적인 두 가지 요소, 정당화 및 계획과정에 관하여 논하였다. 우선적으로 정당화되어야 할 문제점들 중에는: 1) 유동성에 대한 이해와 경제성에 대한 연구, 그리고 2) 노사관계에 관한 문제점들을 고찰하여 각 기업의 특성에 맞게 조절을 해야한다. 이러한 점들에 대한 이해, 연구, 고찰이 이루어지고 정당성이 성립이된 후에는 유동제조시스템을 점차적으로 정착시킨다. 이 진행과정에서 성립되어야 할 점들은 다음과 같다. 첫째, 시스템 채택방법을 택하고, 둘째, 분임조를 결성시켜 설정되어진 과제들을 분담하여 해결해 나아가면서 유동제조시스템이 하나의 고유적인 방법으로 회사의 특색 및 실정에 맞게 정착되도록 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1043-1064
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• 2020

A kind of Subjective Imaging Effect Assessment (SIEA) method and its applications on intelligent imaging terminal design in engineering site are presented. First, some visual assessment indices are used to characterize the imaging effect: the image brightness, the image brightness uniformity, the color image contrast, the image edge blur, the image color difference, the image saturation, the image noise, and the integrated imaging effect index. A linear weighted function is employed to carry out the SIEA computation and the Analytic Hierarchy Process (AHP) technique is used to estimate its weights. Second, a SIEA software is developed. It can play images after the settings of assessment index or assessment reaction time, etc. Third, two cases are used to illustrate the application effects of proposed method: the image enhancement system design for surveillance camera and the imaging environment perception system design for intelligent lighting terminal. A Prior Sequential Stimulus (PSS) experiment is proposed to improve the evaluation stability of SIEA method. Many experiment results have shown the proposed method can realize a stable system design or parameters setting for the intelligent imaging terminal in engineering site.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.4
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• pp.390-396
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• 2013

Due to the development of technology, there is a considerable increase in the number of skyscrapers in the world. Accordingly, there are rapid growing requests about maintenances such as cleaning, painting, and inspection. However, it is extremely dangerous working the walls of buildings, and crashes from buildings have accounted for large proportion of constructional accidents. Especially, as the number of buildings with irregular shapes increases, the accident rate during the maintenance work increases each year, and most of the accidents lead to death. An alternative solution must be developed with the commercialization of automatic systems. In this research, a fundamental research has been conducted for drafting and commercializing an automation tool that is carried in the built-in guide system, which can perform cleaning.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.38-45
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• 2004

Ultrasonic signals transmitted through adhesively bonded plates were used to evaluate parameters related to attenuation and frequency in the adhesively bonded joint. The kinds of bonding materials with a different bonding thickness of constant pressure were used. And ultrasonic diagnosis was evaluated by p-wave sensor of 10MHz. FFT has been performed to determine bond-layer parameters such as effective thickness and frequency for adhesively bonded joint of A16061 plates in comparison with measured to theoretical ratios. When variable thickness exists, the ultrasonic spectrum was changed the frequency wave. The more materials thickness and the higher the frequency, the larger shift was observed. Measured ratios for cases of bond thickness and variety bonding materials are then used to determine bond parameters. The results show that the technique can be applied to the characterization of adhesively bonded joint.

• Journal of Welding and Joining
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• v.21 no.5
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• pp.555-560
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• 2003

In automobile industry, it is necessary to reduce the weight from the view point of energy and environmental problems in these days. One of the ways for weight reduction is using adhesive aluminum structures. In this study, ultrasonic signals reflected from the adhesively bonded joint layer are used to evaluate the adhesively bonded joints. FFT is performed to determine bond-layer parameters such as effective thickness and frequency for adhesively bonded joint Al 6061 plates in comparison with the measured and theoretical ratios. And the parameters of ultrasonic wave and the J-integral are investigated to evaluate the adhesively bonded joint strength by DCB specimens.

• Journal of Welding and Joining
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• v.29 no.3
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• pp.64-69
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• 2011

Since welding process for most pipelines with large diameter has been carried out by the manual process, automation of the welding process is necessary for the sake of consistent weld quality and improvement in productivity. Therefore the development of the optimized algorithm to decide the welding condition is an effective technique to prove the feasibility of interface standards and intelligent control technology to increase productivity and reduce the cost of system integration. In this study, the pipe welding experiment has been carried out using plused GMA welding process to select optimal welding condition. And necessary information in root-pass welding has been obtained by applying in the pipeline using the selected welding conditions through the welding experiment.

• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.83-87
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• 2008

Although a great deal of research has been carried out to solve the plate forming problem and to improve the effectiveness and productivity of the plate forming process, no practical way of automating the plate forming process has been proposed yet. Since characteristics of heating machines may vary, it is necessary to investigate the thermal deformation characteristics of the heating machine that will be used in the automation system its characteristics may be modified as new information about thermal deformation by heating becomes available. In this paper, experiments for line heating have been carried out to calculate the formula of predicting thermal deformation due to line heating with varying affecting parameters, and numerical study has been carried out to produce data beyond the range where a line heating test is impractical. Formulas of predicting transverse distortion and shrinkage have been proposed and derived, based on the present experimental and numerical works. This paper also illustrates how the formula has been modified as new experimental data are added.

• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.95-99
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• 2008

The block assembly of ship consists of a certain type of heat processes such as cutting, bending welding residual stress relaxation and fairing. The residual deformation due to welding is inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding deformation. The validity of the prediction method must be also clarified through experiments. This paper proposes a simplified analysis method to predict the welding deformation of panel block structure. For this purpose, a simple prediction model for fillet welding deformations has been derived based on numerical and experimental results through the regression analysis. On the basis of these results, the simplified analysis method has been applied to some examples to show its validity.