• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.702-721
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• 2012

In the DVB-T2 system with a multiple-input single-output (MISO) transmission mode, Alamouti coded orthogonal frequency division multiplexing (OFDM) signals are transmitted simultaneously from two spatially separated transmitters in a single frequency network (SFN). In such systems, each transmit-receive link may have a distinct carrier frequency offset (CFO) due to the Doppler shift and/or frequency mismatch between the local oscillators. Thus, the received signal experiences dual CFOs. This not only causes dual phase errors in desired data but also introduces inter-carrier interference (ICI), which cannot be removed completely by simply performing a CFO compensation. To overcome this problem, this paper proposes an iterative detection with dual phase errors compensation technique. In addition, we propose a successive-iterative ICI cancellation technique. This technique successively eliminates ICI in the initial iteration by exploiting pre-detected data pairs. Then, in subsequent iterations, it performs a fine interference cancellation using a priori information, iteratively fed back from the channel decoder. In contrast to previous works, the proposed techniques do not require estimates of dual CFOs. Their performances are evaluated via a full DVB-T2 simulator. Simulation results show that the DVB-T2 receiver equipped with the proposed dual phase errors compensation and the successive-iterative ICI cancellation techniques achieves almost the same performance as ideal dual CFOs-free systems, even for large dual CFOs.

• Journal of Internet Computing and Services
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• v.18 no.2
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• pp.53-60
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• 2017

Since processors are handling inputs and outputs independently on distributed memory computers, different file input/output methods are used. In this paper, we implemented and compared various file I/O methods to show their efficiency on distributed memory parallel computers. The implemented I/O systems are as following: (i) parallel I/O using NFS, (ii) sequential I/O on the host processor and domain decomposition, (iii) MPI-IO. For performance analysis, we used a separated file server and multiple processors on one or two computational servers. The results show the file I/O with NFS for inputs and sequential output with domain composition for outputs are best efficient respectively. The MPI-IO result shows unexpectedly the lowest performance.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.475-480
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• 1993

This study was carried out to estimate the bind values of raw meats which are used as an input constaint in the least-cost formulation of an emulsion-type sausage. The least-cost formulation will be useful for Korean meat processore to produce more effectively as meat-grade system is put in force. The analysis results in compositions, functionalities, and pigment contents of raw meats were various according to the difference of species and their parts. The cohesiveness was correlated positively with moisture or protein content and negatively with fat content. Consequently two multiple regression equations for bind value could be derived from the compositions of raw meats. The equations then may be useful for predicting the bind value of a raw meat which presently has not been analysed.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.693-698
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• 2003

Every baseball game generates various records and on the basis of those records, win/lose prediction about the next game is carried out. Researches on win/lose predictions of professional baseball games have been carried out, but there are not so good results yet. Win/lose prediction is very difficult because the choice of features on win/lose predictions among many records is difficult and because the complexity of a learning model is increased due to overlapping factors among the data used in prediction. In this paper, learning features were chosen by opinions of baseball experts and a heuristic function was formed using the chosen features. We propose a hybrid model by creating a new value which can affect predictions by combining multiple features, and thus reducing a dimension of input value which will be used for backpropagation learning algorithm. As the experimental results show, the complexity of backpropagation was reduced and the accuracy of win/lose predictions on professional baseball games was improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5140-5149
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• 2014

The present study examined the relationships of emotional labor, job satisfaction and burnout in medical technologists working at university hospitals. The study subjects were 145 medical technologists and health information technicians working at 4 university hospitals. The investigation was conducted using a standardized self-administered questionnaire from April 10-19, 2013. As a result of hierarchical multiple regression, the socio-demographic characteristics, health-related behavior factors, job-related factors, emotional labor and job satisfaction were selected as significant variables and related variables affecting the level of burnout. The descriptive power of these variables(socio-demographic characteristics, health-related behavior factor) was 21.7%, especially it can be seen that emotional labor and job satisfaction variable input 16.8% and 8.2% increase explanatory power respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.240-247
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• 2004

In order to transmit data at high speed in the wireless environment, OFDM is selected as the transmission method of various high-speed wireless communication system since it has the advantage to deal easily the serious selective frequency fading channel by the multiple path. We evaluate STBC-OFDM and linear STBC-OFDM combining with a class of recently proposed linear scalable space-time block codes and OFDM in MIMO channel environments, and demonstrate the performance for spatial multiplexing and diversity gain. The codes are able to use jointly transmit diversity in combination with spatial multiplexing, and achieve spatial and temporal diversity. Frequency diversity of frequency selective channels can be utilized by combining the linear STBC and OFDM. Simulation results are shown to demonstrate the better performance of proposed approach in comparison with STBC-OFDM.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.177-186
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• 2006

This paper presents the development of a certain highly efficient authoring tool for constructing realistic 3D virtual space using image-based rendering techniques based on a virtual space map. Unlike conventional techniques such as TIP, for constructing a small 3D virtual space using single image, the authoring tool developed herein produces a wide 3D virtual space using multiple images. This tool is designed for constructing each small 3D virtual space for each input image, and for interconnecting these 3D virtual spaces into a wide 3D virtual space using a virtual space map. The map consists of three elements such as specific room, link point and passageway, and three directions. It contains various information such as the connection structure, the navigation information and so on. Also, the tool contains a user interface that let users construct the wide 3D virtual space easily.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.290-299
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• 2010

This study aims to evaluate the efficiency of superior appraisal corporations using DEA(Data Envelopment Analysis). DEA is known as a method for evaluating relative efficiency of organizations with multiple inputs and outputs. We used CCR-O and BCC-O DEA models to evaluate relative efficiency of superior appraisal corporations. Input variable is number of appraisers, output variables are total sales and net income. Total of 13 appraisal corporations in Korea were selected for this study, and the data were collected from financial reports for 2008 fiscal year. The result of this study is summarized as follows. First, the average of superior appraisal corporation's technical efficiency score is about 88.3% by applying CCR-O model. Second, the average of superior appraisal corporation's pure technical efficiency score is about 90% and scale efficiency score is about 98.2% by applying BCC-O model. According to the result of DEA, the cause of inefficiency is pure technical efficiency.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.1 s.24
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• pp.47-56
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• 2007

The parameters are determined analyzing the hydraulic and hydrological characteristics of design floods, watershed, channel length, and river bed slope. The models are calibrated while the input hydrologic data are the field data of middle size areas in Guem river basin in Korea. The basic equations of design width are suggested by the multiple regression analysis and the results show excelled in comparisons as well as calibrations with the existing empirical formulas and the design criteria, respectively. The basic equations of design width in validation process is determined the regression functions with the design floods, watershed, channel length, river bed slope as the four parameters using other database in the same scales watershed. As a results, this study will be used for apply to determine of design width and river alignmentof the watershed in hydraulic fields.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.7
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• pp.945-951
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• 2007

Noise cancellation is essential for the devices which use speech as an interface. In real environments, speech quality and recognition rates are degraded by the auditive noises coming near the microphone. In this paper, we propose a noise cancellation algorithm using stereo microphones basically. The advantage of the use of multiple microphones is that the direction information of the target source could be applied. The proposed noise canceller is based on the Wiener filter. To estimate the filter, noise and target speech frequency responses should be known and they are estimated by the spectral classification in the frequency domain. The performance of the proposed algorithm is compared with that of the well-known Frost algorithm and the generalized sidelobe canceller (GSC) with an adaptation mode controller (AMC). As performance measures, the perceptual evaluation of speech quality (PESQ), which is the most widely used among various objective speech quality methods, and speech recognition rates are adopted.