• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.570-595
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• 2017

Robust and perceptually-adaptive image watermarking algorithms have mainly targeted gray-scale images either at the modeling or embedding levels despite the widespread availability of color images. Only few of the existing algorithms are specifically designed for color images where color correlation and perception are constructively exploited. In this paper, a new perceptual and high-capacity color image watermarking solution is proposed based on the extension of Tsui et al. algorithm. The $CIEL^*a^*b^*$ space and the spatio-chromatic Fourier transform (SCFT) are combined along with a perceptual model to hide watermarks in color images where the embedding process reconciles between the conflicting requirements of digital watermarking. The perceptual model, based on an emerging color image model, exploits the non-uniform just-noticeable color difference (NUJNCD) thresholds of the $CIEL^*a^*b^*$ space. Also, spread-spectrum techniques and semi-random low-density parity check codes (SR-LDPC) are used to boost the watermark robustness and capacity. Unlike, existing color-based models, the data hiding capacity of our scheme relies on a game-theoretic model where upper bounds for watermark embedding are derived. Finally, the proposed watermarking solution outperforms existing color-based watermarking schemes in terms of robustness to standard image/color attacks, hiding capacity and imperceptibility.

• Journal of KSNVE
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• v.10 no.6
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• pp.1048-1058
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• 2000

Thipaper presents a methodology to suppress the vibration of thin rectangular plate clamped all edges using piezo-ceramic material as actuators and sensors. Dynamic characteristics of the structure bonded with distributed actuators/sensors are identified by the Multi-Input Multi-Output (MIMO) frequency domain modeling technique based on the experimental data. Hybrid control scheme is adopted and feedback controller is designed by LQG(Linear Quadratic Gaussian). Feedforward controller is adapted by multiple filtered -$x$ LMS(least mean square) algorithm. Experiment result demonstrates the effective reduction of the vibration label for both the transient and persistent external disturbances.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.507-514
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• 2009

In this study, a dynamic modeling scheme is presented to describe the probabilistic structure of soil water and plant water stress index under stochastic precipitation conditions. The proposed model has the form of the Fokker-Planck equation, and its applicability as a model for the probabilistic evolution of the soil water and plant water stress index is investigated under a climate change scenario. The simulation results of soil water confirm that the proposed soil water model can properly reproduce the observations and show that the soil water behaves with consistent cycle based on the precipitation pattern. The simulation results of plant water stress index show two different PDF patterns according to the precipitation. The simple impact assessment of climate change to soil water and plant water stress is discussed with Korean Meteorological Administration regional climate model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.1082-1089
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• 2006

In this study, advanced computational analysis system has been developed in order to investigate flow-induced vibration(FIV) phenomenon for general stator-rotor cascade configurations. Relative movement of the rotor with respect to stator is reflected by modeling Independent two computational domains. Fluid domains are modeled using the unstructured grid system with dynamic moving and local deforming methods. Unsteady, Reynolds-averaged Wavier-stokes equations with one equation Spalart-Allmaras and two-equation SST ${\kappa}-{\varepsilon}$ turbulence models are solved for unsteady flow problems and also relative moving and vibration effects of the rotor cascade are fully considered. A coupled implicit time marching scheme based on the Newmark integration method is used for computing the governing equations of fluid-structure interaction problems. Detailed vibration responses for different flow conditions are presented and then vibration characteristics are physically investigated in the time domain as computational virtual tests.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.29-34
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• 2007

Numerical analyses are carried out to evaluate the cumulative impact damage of an automotive front end bumper under the low speed crash events(CMVSS215) by using explicit code. Results of first impact simulation, which are deformed shape, thickness, stress tensors and strain tensors, are used as the initial conditions for a next impact simulation. Between the events, the residual vibration is damped out by using nodal damping, and then recovery after each event is evaluated by several methods, one of which is a springback analysis with implicite finite element analysis code. The coupled analysis scheme for the evaluation of cumulative impact damage is verified through the comparison with test results.

• The Journal of Korea Robotics Society
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• v.10 no.4
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• pp.186-192
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• 2015

This paper proposes a robust balance and driving control for omni-directional ball robot(generally called ball-bot) with two axis mecanum wheel. Slip between ball and mecanum wheel actuator inevitably occurs along diagonal axis due to its instantaneous strong torque. In order to reduce and saturate slip, exact distance calculation scheme especially for rotational movement is essential. So this research solved Euler-Lagrange dynamics for proposed two axis ball robot based on practical mechanical modeling. Robust balance control was carried out by PID controller according to the pitch and roll angles of ball robot by using sensor fusion between AHRS and wheel encoder. Proposed PID controller enhances stability by reducing steady state error and settling time. Proposed slip control algorithm for omni-directional ball robot has been demonstrated by experiments for balance control and arbitrary driving control.

• Journal of Engineering Education Research
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• v.17 no.3
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• pp.42-50
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• 2014

Since internships or field training provide students with opportunities to choose skills, business interests and aptitudes in the actual workplace, their significant role in higher education has been gradually emphasized. In particular, engineering students gain increased adaptability to the industry, enhance their research abilities and acquire field-based expertise through internships or field training. However, effective operation of such internships or field training often pose various limitations. In this regard, the development of a system to manage students properly is urgently required for the effective operation of internships or field training. Systematic management of a series of related information ranging from a survey on the demand for internships or field training, planning, development and operation of pre-training programs, student guidance through information sharing between universities and businesses, data-gathering with regard to students' difficulties and their requirements, to prospects for future employment. In line with these requirements, this study attempts to present a modeling scheme for the development of a student management system for use in internships or field training. Towards this end, a questionnaire survey is conducted with engineering professors, students and graduates, along with a review of related literature to identify the needs for system development. Based on the results, a model of the system will be proposed through expert consultation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2405-2423
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• 2012

In a traditional Single Sign-On (SSO) scheme, the user and the Service Providers (SPs) have given their trust to the Identity Provider (IdP) or Authentication Service Provider (ASP) for the authentication and correct assertion. However, we still need a better solution for the local/native true SSO to gain user confidence, whereby the trusted entity must play the role of the ASP between distinct SPs. This technical gap has been filled by Trusted Computing (TC), where the remote attestation approach introduced by the Trusted Computing Group (TCG) is to attest whether the remote platform integrity is indeed trusted or not. In this paper, we demonstrate a Trustworthy Mutual Attestation (TMutualA) protocol as a proof of concept implementation for a local true SSO using the Integrity Measurement Architecture (IMA) with the Trusted Platform Module (TPM). In our proposed protocol, firstly, the user and SP platform integrity are checked (i.e., hardware and software integrity state verification) before allowing access to a protected resource sited at the SP and releasing a user authentication token to the SP. We evaluated the performance of the proposed TMutualA protocol, in particular, the client and server attestation time and the round trip of the mutual attestation time.

• Journal of Environmental Impact Assessment
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• v.22 no.1
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• pp.79-87
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• 2013

The purpose of this study is to establish PM-10 management manual for developing large scale sites by assessing the status of PM-10 reduction at ongoing large scale development sites. After analyzing the meteorological conditions and air quality characteristics of Sihwa MTV development site, ISCST3 (Industrial Source Complex Short Term Model 3) was implemented to predict PM-10 generation. The outcomes of ISCST3 modelling were utilized for verification of site survey data. As a result of applying air pollution modeling, the diffusion rate of PM-10 decreases according as the wind speed decreases. And the emission rate of PM-10 increase is linear to the concentration of PM-10. The reduction target of PM-10 can be derived quantitatively from the difference between the forecasted emission rate and the permissible emission limit of PM-10. The assessment of PM-10 characteristics which is deduced from ISCST3 and site survey can be practically applied to accomplish environmentally acceptable air quality manual for large scale development sites.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.262-271
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• 2005

In order to achieve timely and accurate fault detection of plasma etching process, neural network based time series modeling has been applied to reactive ion etching (RIE) using two different in-situ plasma-monitoring sensors called optical emission spectroscopy (OES) and residual gas analyzer (RGA). Four different subsystems of RIE (such as RF power, chamber pressure, and two gas flows) were considered as potential sources of fault, and multiple degrees of faults were tested. OES and RGA data were simultaneously collected while the etching of benzocyclobutene (BCB) in a $SF_6/O_2$ plasma was taking place. To simulate established TSNNs as incipient fault detectors, each TSNN was trained to learn the parameters at t, t+T, ... , and t+4T. This prediction scheme could effectively compensate run-time-delay (RTD) caused by data preprocessing and computation. Satisfying results are presented in this paper, and it turned out that OES is more sensitive to RF power and RGA is to chamber pressure and gas flows. Therefore, the combination of these two sensors is recommended for better fault detection, and they show a potential to the applications of not only incipient fault detection but also incipient real-time diagnosis.