• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1163-1170
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• 2014

Due to global environmental regulations and policies with rapid advancement of renewable energy technologies, the development type of renewable energy sources (RES) in power systems is expanding from small-scale distributed generation to large-scale grid-connected systems. In the near future, it is expected that RES achieves grid parity which means the equilibrium point where the power cost of RES is equal to the power costs of conventional generators. However, although RES would achieve the grid parity, the cost related with development of large-scale RES is still a big burden. Furthermore, it is hard to determine a suitable capacity of RES because of their output characteristics affected by locations and weather effects. Therefore, to determine an optimal capacity for RES becomes an important decision-making problem. This study proposes a method for determining an optimal installed capacity of RES from the business viewpoint of an independent power plant (IPP). In order to verify the proposed method, we have performed case studies on real power system in Incheon and Shiheung areas, South Korea.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1262-1270
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• 2017

Among various decoding algorithms of low-density parity-check (LDPC) codes, the min-sum (MS) algorithm and its modified algorithms are widely adopted because of their computational simplicity compared to the sum-product (SP) algorithm with slight loss of decoding performance. In the MS algorithm, the magnitude of the output message from a check node (CN) processing unit is decided by either the smallest or the next smallest input message which are denoted as min1 and min2, respectively. It has been shown that multiplying a scaling factor to the output of CN message will improve the decoding performance. Further, Zhong et al. have shown that multiplying different scaling factors (called a 2-dimensional scaling) to min1 and min2 much increases the performance of the LDPC decoder. In this paper, the simplified 2-dimensional scaled (S2DS) MS algorithm is proposed. In the proposed algorithm, we figure out a pair of the most efficient scaling factors which multiplications can be replaced with combinations of addition and shift operations. Furthermore, one scaling operation is approximated by the difference between min1 and min2. The simulation results show that S2DS achieves the error correcting performance which is close to or outperforms the SP algorithm regardless of coding rates, and its computational complexity is the lowest comparing to modified versions of MS algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.763-767
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• 2005

RAID were proposed to stored double data or used to parity logging methode for error recovery. We describe a technique for automating the execution of redundant disk array operation, including recovery from errors, independent of array architecture. RAID5 provide highly reliable cost effective secondary storage with high performance for read access and large write accessed. It discusses the two architectural techniques used in disk arrays, striping across multiple disks to improve performance and redundancy to improve reliability. In this paper we compare with performance and reliability in RAID5 real/write to file and stripe size. than suggest to algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.415-418
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• 2011

This paper describes a circuit-level optimization of DFU(decoding function unit) for LDPC decoder which is used in wireless communication systems such as WiMAX and WLAN. The conventional DFU which is based on min-sum decoding algorithm needs conversions between two's complement values and sign-magnitude values, resulting in complex hardware. In this paper, a new design of DFU that is based on sign-magnitude arithmetic is proposed to achieve a simplified circuit and high-speed operation.

• The KIPS Transactions:PartA
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• v.13A no.3 s.100
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• pp.241-252
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• 2006

In cluster file systems, the availability of files has been supported by replicating entire files or generating parities on parity servers. However, those methods require very large temporal and spatial cost, and cannot handle massive failures situation on the file system. So we propose HA-PVFS, a cluster file system supporting high data availability adaptive to temporal locality. HA-PVFS restricts replication or parity generation to some important files, for that it employs an efficient algorithm to estimate file access patterns from limited information. Moreover, in order to minimize the performance degradation of the file system, it uses delayed update method and relay replication.

• Journal of Embryo Transfer
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• v.12 no.1
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• pp.49-56
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• 1997

This study was carried out to establish an effective and practical system for commercialization of embryo production techniques by analyzing several factors influencing in vivo embryo production on condition of donors treated FSH-P and SUPER-OV in Korean native cattle. In vivo embryos were flushed 226 times from 128 donors. The results obtained for the factors influencing in vivo embryo production by conditionof donors treated FSH-P and SUPER-OV were as follows :1. Age and parity of donors did not affect the transferable and freezable embryos among the treatments in FSH-P but the transferable and freezable embryos were decreased after 6 years old and 4th parity in SUPER-OV(P<0.01). 2. The production of embryos on the weight of donors was higher in over 400kg of body weight in FSH-P(P<0.01) and was higher in over 450kg than 400~450kg of body weight in SUPER-OV(P<0.05). For FSH-P embryo production was better responded in 350~450kg of body weight with 30~32mg doses, and showed a better result in over 450kg body weight with 32~34mg doses.(Key Words : in vivo embryo, donors, FSH-P SUPER-OV)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.432-438
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• 2011

This paper describes an analysis of optimal design conditions of multi-mode LDPC(low density parity check) decoder which supports three block lengths (648, 1296, 1944) and four code rates (1/2, 2/3, 3/4, 5/6) for IEEE 802.11n WLAN system. A fixed-point model of LDPC decoder, which adopts min-sum algorithm and layered decoding scheme, is implemented using Matlab. From fixed-point simulation results for various bit-width parameters such as internal bit-width, integer/fractional part bit-widths, optimal design conditions and decoding performance of LDPC decoder are analyzed.

• The Transactions of the Korea Information Processing Society
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• v.4 no.11
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• pp.2690-2700
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• 1997

This paper presents parallel sorting algorithm, SHARED-MEMORY-BS and REDUCED-BS, which are implemented on shared-memory parallel computers. These algorithm sort N keys in $O(log^2N)$ time. REDUCED-BS users a parity strategy which gives an idea for the efficient usage of the local memory associated with each processor. By taking advantage of the local memory associated with each processor, the communication of REDUCED-BS is decreased by approximately half that of SHARED-MEMORY-BS. On the basis of alleviating the communication, the algorithm REDUCED-BS results in a significant improvement of performance.

• The Journal of Korean Obstetrics and Gynecology
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• v.21 no.4
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• pp.128-138
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• 2008

Purpose: The purpose of this study was to compare the CBC and HRV of postpartum women in the early 30s. according to parity. Methods: This study was done on 107 postpartum women between 30 and 34 years who admitted for postpartum care in Oriental Hospital of Woosuk University from 3rd February 2008 to 19th September 2008. They took the test of CBC and HRV. The SPSS 12.0 for windows was used to analyze the data and the independent samples t-test were used to verify the results. Results: 1. WBC and Grn of primipara group significantly increased compared with that of multipara group. LYM of multipara group significantly increased compared with that of primipara group. 2. Mean-RR and Complexity of multipara group significantly increased compared with that of primipara group. Mean-HR of primipara group significantly increased compared with that of multipara group. 3. Ln (HF) and Normalized HF of multipara group significantly increased compared with that of primipara group. Normalized LF of primipara group significantly increased compared with that of multipara group. Conclusion: The findings suggest that activation of the sympathetic nervous system in primipara group is higher than in multipara group. and activation of the parasympathetic nervous system in primipara group is lower than in multipara group.

• Asia-Pacific Journal of Business
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• v.13 no.2
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• pp.123-138
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• 2022

Purpose - This study compares the performances of dynamic asset allocation strategies using Korean stocks and U.S. dollar, which have been negatively correlated for a long time, to examine the diversification effects in the portfolios of them. Design/methodology/approach - In the current study, we use KOSPI200 index, as a proxy of the aggregated portfolio of Korean stocks, and USDKRW foreign exchange rate to implement various portfolio management strategies. We consider the equally-weighted, risk-parity, minimum variance, most diversified, and growth optimal portfolios for comparison. Findings - We first find the enhancement of risk adjusted returns due to risk reduction rather than return increasement for all the portfolios of consideration. Second, the enhancement is more pronounced for the trading strategies using correlations as well as volatilities compared to those using volatilities only. Third, the diversification effect has become stronger after the global financial crisis in 2008. Lastly, we find that the performance of the growth optimal portfolio can be improved by utilizing the well-known momentum phenomenon in stock markets to select the length of the sample period to estimate the expected return. Research implications or Originality - This study shows the potential benefits of adding the U.S. dollar to the portfolios of Korean stocks. The current study is the first to investigate the portfolio of Korean stocks and U.S. dollar from investment perspective.