• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.19-23
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• 2018

In a Pb-included piezoelectric composition, $Sr_yPb_{1-y}[(Zn_{1/3}Nb_{2/3})_x-(Ni_{1/3}Nb_{2/3})_{0.2}-(Zr_{0.46}Ti_{0.54})_{0.8-x}]O_3$ was selected in order to attain high piezoelectric properties. According to the PZN ratio (x) and the amount of Sr doping (y), the crystal structure, microstructure and piezoelectric properties were measured and evaluated. In the case of Sr 4 mol% doping, the piezoelectric properties were the highest for a PZN ratio of 0.1. In this condition, the grain size was larger and the intensity was higher. With the PZN ratio fixed and varying the Sr doping, the piezoelectric properties increased until 10 mol% doping and then decreased for over 12 mol% doping. In the case of x＝0.1 and y＝10 mol%, the best piezoelectric properties were obtained, i.e., $d_{33}=660pC/N$ and $k_p=68.5%$, and these values seem to be related to the grain size and crystal structure.

• Korean Journal of Computational Design and Engineering
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• v.20 no.2
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• pp.193-209
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• 2015

For reasons such as global warming, depletion of fossil fuels and the danger of nuclear energy the research and development of renewable energy is actively underway. Wind energy has advantages over another renewable energy in terms of location requirements, energy efficiency and reliability. Nowadays the research and development area is expanded to offshore because it can supply more wind reliability and free from noise pollution. In this study, the monopile offshore wind turbine transportation and installation (T&I) process are investigated. In addition, the schedule and cost for the process are estimated by discrete event simulation. For the simulation, simulation models for various means of T&I are developed. The optimum T&I execution plan with shortest duration and lowest cost can be found by using different mission start day and T&I means.

• Journal of Industrial Convergence
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• v.6 no.2
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• pp.1-27
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• 2008

This thesis is to analyze and investigate the influence of behaviors towards an organization of public officials due to the way their parents raised them. I tried to find out how their parents' raising way influences the individual characteristics, the human relationship, the job satisfaction, and the organizational commitment. It is proved that the personal characteristics of the organization members affect the human relationship in organization strongly. It is also proved that the way their parents raised them affects the personal characteristics. Therefore I can suggest that the way parents raised children affects the organizational behavior strongly. In addition to that, the personal characteristics of each public official highly affect the human relationship such as the relationship with seniors, colleagues, and subordinates in organization. I know that the way their parents raised them strongly affects the human relationships in organization. In order to find out the influence of organizational behavior of public officials due to the way their parents raised them, I used the Pearson's correlation analysis. I find that the public officials who lived with positive parents have high job satisfaction and organizational commitment, and have high self-esteem, self-control, responsibility, and have good relationship with their senior and colleagues administrative public official. Also, from this study we can find out the influence which parents' attitude has on children's satisfaction and devotion as adults. Therefore this study can suggest a new direction of public administration.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.71-71
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• 2011

Dye-sensitized solar cells (DSCs) have drawn great academic attention due to their potential as low-cost renewable energy sources. DSCs contain a nanostructured TiO2 photoanode, which is a key-component for high conversion efficiency. Particularly, one-dimensional (1-D) nanostructured photoanodes can enhance the electron transport for the efficient collection to the conducting substrate in competition with the recombination processes. This is because photoelectron colletion is determined by trapping/detrapping events along the site of the electron traps (defects, surface states, grain boundaries, and self-trapping). Therefore, 1-D nanostructured photoanodes are advantageous for the fast electron transport due to their desirable features of greatly reduced intercrystalline contacts with specified directionality. In particular, anodic TiO2 nanotube (NT) electrodes recently have been intensively explored owing to their ideal structure for application in DSCs. Besides the enhanced electron transport properties resulted from the 1-D structure, highly ordered and vertically oriented nanostructure of anodic TiO2 NT can contribute additional merits, such as enhanced electrolyte diffusion, better interfacial contact with viscous electrolytes. First, to confirm the advantages of 1-D nanostructured material for the photoelectron collection, we compared the electron transport and charge recombination characteristics between nanoparticle (NP)- and nanorod (NR)-based photoanodes in DSCs by the stepped light-induced transient measurements of photocurrent and voltage (SLIM-PCV). We confirmed that the electron lifetime of the NR-based photoanode was much longer than that of the NP-based photoanode. In addition, highly ordered and vertically oriented TiO2 NT photoanodes were prepared by electrochemical anodization method. We compared the photovoltaic properties of DSCs utilizing TiO2 NT photoanodes prepared by one-step anodization and two-step anodization. And, to reduce the charge recombination rate, energy barrier layer (ZnO, Al2O3)-coated TiO2 NTs also applied in DSC. Furthermore, we applied the TiO2 NT photoanode in DSCs using a viscous electrolyte, i.e., cobalt bipyridyl redox electrolyte, and confirmed that the pore structure of NT array can enhance the performances of this viscous electrolyte.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.113-117
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• 2016

Temperature dependent reverse-bias current-voltage (I-V) characteristics in Cu Schottky contacts to oxygen plasma treated n-InP were investigated. For untreated sample, current transport mechanisms at low and high temperatures were explained by thermionic emission (TE) and TE combined with barrier lowering, respectively. For plasma treated sample, experimental I-V data were explained by TE or TE combined with barrier lowering models at low and high temperatures. However, the current transport was explained by a thermionic field emission (TFE) model at intermediate temperatures. From X-ray photoemission spectroscopy (XPS) measurements, phosphorus vacancies (VP) were suggested to be generated after oxygen plasma treatment. V_P possibly involves defects contributing to the current transport at intermediate temperatures. Therefore, minimizing the generation of these defects after oxygen plasma treatment is required to reduce the reverse-bias leakage current.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.285-289
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• 2015

We prepared silver Schottky contacts to O-polar and nonpolar m-plane bulk ZnO wafers. Then, by considering various transport models, we performed a comparative analysis of the current transport properties of Ag/bulk ZnO Schottky diodes, which were measured at 300, 200, and 100 K. The fitting of the forward bias current-voltage (I-V) characteristics revealed that the tunneling current is dominant as the transport component in both the samples. Compared to thermionic emission (TE), a stronger contribution of tunneling current was observed at low temperature. The reverse bias I-V characteristics were well fitted with the thermionic field emission (TFE) in both the samples. The presence of acceptor-like adsorbates, such as O₂ and H₂O, modulated the surface conductive state of ZnO, thereby affecting the tunneling effect. The degree of activation/passivation of acceptor-like adsorbates might be different in both the samples owing to their different surface morphologies and surface defects (e.g., oxygen vacancies).

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.29-33
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• 2008

This paper presents the proposal and hardware design of JPEG baseline encoder. The JPEG encoder system consists of line buffer, 2-D DCT, quantization, entropy encoding, and packer. A fully pipelined scheme for JPEG encoder is adopted to speed-up an image compression. The proposed architecture was described in VHDL and synthesized in Xilinx ISE 7.1i and simulated by modelsim 6.1i. The results showed that the performance of the designed JPEG baseline encoder is higher than that demanded by real-time applications for $1024{\times}768$ image size. The designed JPEG encoder IP can be easily integrated into various application systems, such as scanner, PC camera, color FAX, and network camera, etc.

• International journal of advanced smart convergence
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• v.1 no.2
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• pp.26-29
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• 2012

Recently, to efficiently support the real-time requirements of RTLS( Real Time Location System) services, interest in the main memory DBMS is rising. In the main memory DBMS, because all data can be lost when the system failure happens, the recovery method is very important for the stability of the database. Especially, disk I/O in executing the log and the checkpoint becomes the bottleneck of letting down the total system performance. Therefore, it is urgently necessary to research about the recovery method to reduce disk I/O in the main memory DBMS. Therefore, In this paper, we analyzed existing log techniques and check point techniques and existing main memory DBMSs' recovery techniques for recovery techniques research for main memory DBMS.

• International journal of advanced smart convergence
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• v.1 no.1
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• pp.6-13
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• 2012

An improved algorithm for image quality assessment is presented. First a simple model of human visual system, consisting of a nonlinear function and a 2-D filter, processes the input images. This filter has one user-defined parameter, whose value depends on the reference image. This way the algorithm can adapt to different scenarios. In the next step the average value of locally computed correlation coefficients between the two processed images is found. This criterion is closely related to the way in which human observer assesses image quality. Finally, image quality measure is computed as the average value of locally computed correlation coefficients, adjusted by the average correlation coefficient between the reference and error images. By this approach the proposed measure differentiates between the random and signal dependant distortions, which have different effects on human observer. Performance of the proposed quality measure is illustrated by examples involving images with different types of degradation.

• Journal of Multimedia Information System
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• v.8 no.1
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• pp.31-34
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• 2021

The classical HMM is defined by a parameter triple �� = (��, A, B), where each parameter represents a collection of probability distributions: initial state, state transition and output distributions in order. This paper proposes a new stationary parameter e = (e1, e2, …, eN) where N is the number of states and et = P(|xt = i, y) for describing how an input pattern y ends in state xt = i at time t followed by nothing. It is often said that all is well that ends well. We argue here that all should end well. The paper sets the framework for the theory and presents an efficient inference and training algorithms based on dynamic programming and expectation-maximization. The proposed model is applicable to analyzing any sequential data with two or more finite segmental patterns are concatenated, each forming a context to its neighbors. Experiments on online Hangul handwriting characters have proven the effect of the proposed augmentation in terms of highly intuitive segmentation as well as recognition performance and 13.2% error rate reduction.