• Journal of Internet Computing and Services
• /
• v.15 no.2
• /
• pp.9-18
• /
• 2014

The sensors attached on/in a person are moved since human body frequency changes their activity, therefore in wireless body area networks, nodal mobility and non-line-of-sight condition will impact on performance of networks such as energy efficiency and reliable communication. We then proposed schemes which study on forwarding decisions against frequent change of topology and channel conditions to increase reliable connections and improve energy efficiency. In this work, we control the size of packets, forwarding rate based on ratio of input links and output links at each node. We also robust the network topology by extending the peer to peer IEEE 802.15.4-based. The adaptive topology from chain-based to grid-based can optimal our schemes. The simulation shows that these approaches are not only extending network lifetime to 48.2 percent but also increase around 6.08 percent the packet delivery ratio. The "hot spots" problem is also resolved with this approach.

• Journal of Korea Multimedia Society
• /
• v.10 no.5
• /
• pp.569-582
• /
• 2007

Digital watermarking technique for copyright protection and prevention of illegal copy and distribution can provide the reliable transaction to both buyer and seller in e-commerce through the cryptographic protocol such as 'Buyer-seller watermarking protocol'. Recently there has been researched about some cryptographic protocols for watermarking system but there has no yet mentioned about the implementation of practical watermarking technique in protocol. This paper presents the watermark embedding technique based on POCS in buyer-seller watermarking protocol. The proposed method designs the robust convex set based on EZW and the invisible convex set using PSNR and then projects into two sets until the convergence condition is satisfied. Experimental results verified that BER of watermark that is embedded by the proposed method has lower 0.02-0.10 than BER of the conventional method.

• Journal of Navigation and Port Research
• /
• v.32 no.10
• /
• pp.851-856
• /
• 2008

Construction of large-scale container ports with the productivity improvements in container cranes shortened time of staying port to increase the level of service it harbors efforts accelerated. About container crane system exerted on the input, which is designed to look good performance considering the states feedback control system. The states observer designed of container cranes state variables that are expected to measurement noise or particular measurement signal. In the status of existing research, the feedback gain matrix and the state observer gain matrix are searched by being separated solving. But the feedback gain matrix and the state observer gain matrix are searched by RCGAs at once that be used robust search method in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.4
• /
• pp.620-626
• /
• 2008

We propose a feature map method to detect a collision for a motion-based game. The feature map can be made an optimally reduced motion data using subtraction image and virtual ball images according to image size and condition. And we calculate the overlapped ratio between moving image data and objects. This ratio is an invariant for detection even though image size is changed. And we compare this ration with collision detection constant, the feature map can detect fast collisions as well as the collided direction. To evaluate the method, we implemented a motion-base game that consists of a web cam, a player, an enemy, and some virtual balls, and we obtained some valid results for our method for the collision detection. The results demonstrated that the proposed approach is robust, and they can be used as a basic collide detection algorithm for a motion-based game where the size and the position of characters are continuously changing.

• Smart Structures and Systems
• /
• v.18 no.3
• /
• pp.501-523
• /
• 2016

Electromechanical impedance (EMI) based structural health monitoring is performed by measuring the variation in the impedance due to the structural local damage. The impedance signals are acquired from the piezoelectric patches that are bonded on the structural surface. The impedance variation, which is directly related to the mechanical properties of the structure, indicates the presence of local structural damage. Two traditional EMI-based damage detection methods are based on calculating the difference between the measured impedance signals in the frequency domain from the baseline and the current structures. In this paper, a new structural damage detection approach by analyzing the time domain impedance responses is proposed. The measured time domain responses from the piezoelectric transducers will be used for analysis. With the use of the Time Frequency Autoregressive Moving Average (TFARMA) model, a damage index based on Singular Value Decomposition (SVD) is defined to identify the existence of the structural local damage. Experimental studies on a space steel truss bridge model in the laboratory are conducted to verify the proposed approach. Four piezoelectric transducers are attached at different locations and excited by a sweep-frequency signal. The impedance responses at different locations are analyzed with TFARMA model to investigate the effectiveness and performance of the proposed approach. The results demonstrate that the proposed approach is very sensitive and robust in detecting the bolt damage in the gusset plates of steel truss bridges.

• Asia-Pacific Journal of Business
• /
• v.11 no.3
• /
• pp.47-61
• /
• 2020

Purpose - This study investigates the relationship between firm-specific, general human capital and corporate innovation performance. Also, we examine when this relationship is more salient. Design/methodology/approach - We collected 1,195 survey data related to a sample of corporate innovation performance and human capital from 1) Korea Research for Vocational Education and Training and 2) NICE information service in Korea. In order to examine the corporate innovation performance, we use the ordered logit model. Findings - First, we find robust supports for our hypothesis that firm-specific and general human capital increase corporate innovation performance. Second, the effect of general human capital on corporate innovation performance is stronger when this relationship is combined with the firm international experience. Research implications or Originality - By integrating the human capital theory and corporate innovation literature, we propose that firm-specific and general human capital are the important determinant of innovation performance. The firm-specific human capital may increase innovation efficiencies. Also, retaining higher-quality general human capital is considered as an important innovation strategy since firms with higher-quality general human capital make greater innovation performance. Further, we show that the firm international experience is the crucial boundary condition. As a firm's experience in internationalization increases, firms can enhance the opportunities to develop new products by combining the skills and knowledge derived from general human capital with the experience gained through internationalization.

• 한국노년학
• /
• v.37 no.1
• /
• pp.33-54
• /
• 2017

This narrative-based study explored the extent to which acculturation level, health condition and SES influence depressive symptoms mediated or moderated by perceived respect of Korean-American older adults in the Chicago metropolitan and its suburban area. For the purpose of the study, qualitative interviews were performed and obtained robust data from 2 focus groups, 2 in-depth interviews. This study produced results by ATLAS. ti,. Qualitative analysis revealed that acculturation could influence depressive symptoms and that depressive symptoms could also be associated with hope and communication. These findings suggested that services given by service providers need to focus on communication and respect of the older Korean-American immigrants' self-determination, for they depend on it greatly when faced with the sufferings from various depressive mood changes in adjusting to new residences.

• The Journal of the Acoustical Society of Korea
• /
• v.38 no.1
• /
• pp.51-55
• /
• 2019

This paper proposes a speech enhancement method utilizing the feature compensation gain for robust speech recognition performances in noisy environments. In this paper we propose a speech enhancement method utilizing the feature compensation gain which is obtained from the PCGMM (Parallel Combined Gaussian Mixture Model)-based feature compensation method employing variational model composition. The experimental results show that the proposed method significantly outperforms the conventional front-end algorithms and our previous research over various background noise types and SNR (Signal to Noise Ratio) conditions in mismatched ASR (Automatic Speech Recognition) system condition. The computation complexity is significantly reduced by employing the noise model selection technique with maintaining the speech recognition performance at a similar level.

• The Journal of Korean Institute of Information Technology
• /
• v.16 no.11
• /
• pp.97-103
• /
• 2018

In this paper, the estimation method for the power signal harmonics is proposed by using the time-varying optimal finite impulse response (FIR) filter. To estimate the magnitude and phase-angle of the harmonic components, the time-varying optimal FIR filter is designed for the state space representation of the noisy power signal which the magnitude and phase is considered as a stochastic process. Since the time-varying optimal FIR filter used in the proposed method does not use any priori information of the initial condition and has FIR structure, the proposed method could overcome the demerits of Kalman filter based method such as poor estimation and divergence problem. Due to the FIR structure, the proposed method is more robust against to the model uncertainty than the Kalman filter. Moreover, the proposed method gives more general solution than the time-invariant optimal FIR filter based harmonic estimation method. To verify the performance and robustness of the proposed method, the proposed method is compared with time-varying Kalman filter based method through simulation.

• Korean Chemical Engineering Research
• /
• v.59 no.1
• /
• pp.77-84
• /
• 2021

To control hot spot in a plug flow reactor (PFR) is important for the yield and purity of products and safety. In this paper, coolant temperature is set as a state variable, and radial distributions of heat and mass are considered to model the PFR more realistic than without considering radial distributions. The model consists of three state variables, reactant concentration, reactant temperature, and the coolant temperature. The flow rate of the isothermal coolant is a manipulated variable. This paper shows that the controller considering the radial distributions of heat and mass is more effective than the controller without them. Assuming that u3,0 is 0.7, the suggested control equation was robust when St is bigger than 1.3, and Ac/A is smaller than 2.0. Under this condition, the hot spot temperature changed within the relative error of one percent when the temperature of input altered within the range of five percent.