• The Korean Journal of Financial Management
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• v.22 no.2
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• pp.189-212
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• 2005

This study examines the interactions between KTB spot and futures markets using the daily prices from March 4, 2002 to January 31, 2005. We use Granger causality test, impulse Response Analysis and Variance Decomposition through vector autoregressive analysis (VAR). However, considering the long-term relationships between the level variables of KTB spot and futures, we introduced Vector Error Correction Model. The main results are as follows. According to the results of Granger-causality test and impulse response analysis, we find that the yields of KTB forward have a great influence on the change of KTB spot but not vice versa. In terms of volatility analysis, there is no inter-dependence between KTB forward and spot markets. In the variance decomposition analysis we find that the short-term KTB forward has much more impact on the KTB spot market than the long-term KTB forward does. We think these results are meaningful for bond investors who are in charge of capital asset pricing valuation, risk management and international portfolio management.

• Journal of Convergence Society for SMB
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• v.6 no.4
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• pp.93-98
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• 2016

Recently, the project related to the smart grid are being actively studied around the developed world. In particular, the long-term stabilization measures distributed power supply problem has been highlighted. In this paper, we propose a three-dimensional numerical weather prediction models to compare the error rate information which combined with the physical models and statistical models to predict the output of distributed power. Proposed model can predict the system for a stable power grid-can improve the prediction information of the distributed power. In performance evaluation, proposed model was a generation forecasting accuracy improved by 4.6%, temperature compensated prediction accuracy was improved by 3.5%. Finally, the solar radiation correction accuracy is improved by 1.1%.

• Korean Journal of Construction Engineering and Management
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• v.14 no.1
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• pp.43-51
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• 2013

The changes in business structure of domestic construction companies suggest that there is a close relationship between the volume of overseas project and a company's financial condition. Based on this assumption, this study conducts an empirical analysis on a relationship between overseas project and financial stability of a construction company. The ratio of liquidity and liability was used as liquidity index and stability index respectively. The analysis was based on quarterly time-series data between 2000 and 2010. Two models were constructed for the analysis: Model 1 was based on the liquidity ratio and the amount of domestic and overseas construction project; Model 2 was based on the debt ratio and the amount of domestic and overseas construction project. The analysis results showed that the increasing amount of overseas project facilitated short-term financing with greater liquidity, and yet it was not very effective in lowering the debt ratio. This suggests that the dramatic increase in overseas construction project, which is observed recently, is not entirely an optimistic sign.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12A
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• pp.1387-1395
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• 2004

Turbo decoder inherently requires large memory and intensive hardware complexity due to iterative decoding, despite of excellent decoding efficiency. To decrease the memory space and reduce hardware complexity, various design issues have to be discussed. In this paper, various design issues on Turbo decoder are investigated and the tradeoffs between the hardware complexity and the performance are analyzed. Through the various simulations on the fixed-length analysis, we decided 5-bits for the received data, 6-bits for a priori information, and 7-bits for the quantization state metric, so the performance gets close to that of infinite precision. The MAX operation which is the main function of Log-MAP decoding algorithm is analyzed and the error correction term for MAX* operation can be efficiently implemented with very small hardware overhead. The size of the sliding window was decided as 32 to reduce the state metric memory space and to achieve an acceptable BER.

• Journal of The Korean Astronomical Society
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• v.42 no.6
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• pp.161-174
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• 2009

Observation of standard stars is of crucial importance in stellar photometry. We have studied the standard transformation relations of the UBV RI CCD photometric system at the Maidanak Astronomical Observatory in Uzbekistan. All observations were made with the AZT-22 1.5m telescope, SITe 2k CCD or Fairchild 486 CCD, and standard Bessell UBV RI filters from 2003 August to 2007 September. We observed many standard stars around the celestial equator observed by SAAO astronomers. The atmospheric extinction coefficients, photometric zero points, and time variation of photometric zero points of each night were determined. Secondary extinction coefficients and photometric zero points were very stable, while primary extinction coefficients showed a distinct seasonal variation. We also determined the transformation coefficients for each filter. For B, V, R, and I filters, the transformation to the SAAO standard system could be achieved with a straight line or a combination of two straight lines. However, in the case of the U filter and Fairchild 486 CCD combination, a significant non-linear correction term - related to the size of Balmer jump or the strength of the Balmer lines - of up to 0:08 mags was required. We found that our data matched well the SAAO photometry in V, B - V, V - I, and R - I. But in U - B, the difference in zero point was about 3.6 mmag and the scatter was about 0.02 mag. We attribute the relatively large scatter in U -B to the larger error in U of the SAAO photometry. We confirm the mostly small differences between the SAAO standard UBV RI system and the Landolt standard system. We also attempted to interpret the seasonal variation of the atmospheric extinction coefficients in the context of scattering sources in the earth's atmosphere.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.9 s.339
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• pp.73-80
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• 2005

The Turbo decoders based on Log-MAP decoding algorithm inherently requires large amount of memory and intensive complexity of hardware due to iterative decoding, despite of excellent decoding efficiency. To decrease the large amount of memory and reduce hardware complexity, the result of previous research. And this paper design the Turbo decoder applicable to the 3G W-CDMA systems. Through the result of previous research, we decided 5-bits for the received data 6-bits for a priori information, and 7-bits for the quantization state metrics. The error correction term for $MAX^{*}$ operation which is the main function of Log-MAP decoding algorithm is implemented with very small hardware overhead. The proposed Turbo decoder is synthesized in $0.35\mu$m Hynix CMOS technology. The synthesized result for the Turbo decoder shows that it supports a maximum 9Mbps data rate, and a BER of $10^{-6}$ is achieved(Eb/No=1.0dB, 5 iterations, and the interleaver size $\geq$ 2000).

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.137-145
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• 2020

The aim of this study is to find out the time-series nexus of public debt and economic growth in Malaysia. For an upper-middle income country, Malaysia had experienced over 50% ratio of debt to GDP since 2009 until now. The question arises is whether this trend is healthy to the economy. With a focus into the debt-to-GDP ratio from 1970-2015, this study investigates the short-run and long-run relationship between public debt and economic growth in Malaysia. This study used secondary data by collecting time-series data (1970-2015) from the World Bank Data and Bank Negara Malaysia. Autoregressive Distributed Lag (ARDL) model is applied in this study to examine the relationship between debt and economic growth. Based on ARDL framework, it shows that there is a long-run effect between the debt and economic growth in Malaysia. While the significance value of Error Correction Term shows that there is a long-run adjustment in the short run. Generally, this study found government expenditures, in the long run, strongly influence the GDP per capita. Through the findings, the government expenditures could increase the GDP per capita. The study also reveals that any increment of the debt ratio will result in reduction of the GDP per capita.

• Journal of Korea Port Economic Association
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• v.27 no.4
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• pp.207-218
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• 2011

This paper investigates the determinants of trade on Southeast Asia via Korean ports using monthly data. I employ Johansen cointegration methodology since the model must be stationary to avoid the spurious results. Johansen(1988) and Johansen and Juselius(1990) propose two statistics for testing the number of cointegrating vectors: the trace and maximum eigenvalue statistics. The null hypothesis that there is no cointegrating vector should be rejected at the 5% level. The results indicate that there is a long-run relationship between trade and variables. This also suggests that these variables have a meaningful equilibrium relationship between trade and variables would not move too far away from each other, displaying a comovement phenomenon for the export and import. Apparently, the error correction term reflects market information in a state of disequilibrium that is bound to be corrected when moving toward the long-run level.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1048-1057
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• 2017

An indirect matrix converter (IMC) is a modern power generation system that enables a direct ac/ac conversion without the need for any bulky and limited lifetime electrolytic capacitor. This system also allows four-quadrant operation, generation of sinusoidal output voltage waveforms with variable frequency and amplitude, and control of input power factor. This study proposes a pulse-width modulation-based sliding-mode controller to achieve unity input-power factor operation of the IMC independently of the active power exchanged with the grid, as well as a fast dynamic response. The designed equivalent control law determines, at each sampling period, the appropriate q-axis component of the modulated input current to be injected into the grid through the LC input filter. An integral term of the error is included in the expression of the sliding surface to increase the accuracy of the control method. A double space vector modulation method is used to synthesize the direction of the space vector of the input currents as required by the sliding-mode controller and the space vectors of the target output voltages. Simulation and experimental results are provided to show the effectiveness and evaluate the performance of the proposed control method.

• International Area Studies Review
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• v.15 no.3
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• pp.215-237
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• 2011

The paper is basically designed to reveal substitutability or complementary nature of export and import among Korea, China, and Japan by employing unit root test, cointegration technique, and vector error correction model(VECM). Empirical evidences are shown that the trading among these countries has been dominated by a complementary nature in the short run which enables it to promote trading in those countries. In the long run, however, the substitutability nature effects strongly to the trading among Korea, China, and Japan. To this end, it could be tentatively concluded that market-oriented trading policies are more effective to stimulate the export and import in those countries in the short run, while a trading policy has to be selectively implemented by the substitutability nature in the long run basis. For instance, a stability policy for exchange rates and various commercial policies could be set for a short term target. Whereas, the substitutability nature should be counted in building up a new industrial structure or in implementing FTA agreement among Korea, China, and Japan.