• BMB Reports
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• v.47 no.11
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• pp.609-618
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• 2014

DNA methylation at cytosines (5mC) is a major epigenetic modification involved in the regulation of multiple biological processes in mammals. How methylation is reversed was until recently poorly understood. The family of dioxygenases commonly known as Ten-eleven translocation (Tet) proteins are responsible for the oxidation of 5mC into three new forms, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Current models link Tet-mediated 5mC oxidation with active DNA demethylation. The higher oxidation products (5fC and 5caC) are recognized and excised by the DNA glycosylase TDG via the base excision repair pathway. Like DNA methyltransferases, Tet enzymes are important for embryonic development. We will examine the mechanism and biological significance of Tet-mediated 5mC oxidation in the context of pronuclear DNA demethylation in mouse early embryos. In contrast to its role in active demethylation in the germ cells and early embryo, a number of lines of evidence suggest that the intragenic 5hmC present in brain may act as a stable mark instead. This short review explores mechanistic aspects of TET oxidation activity, the impact Tet enzymes have on epigenome organization and their contribution to the regulation of early embryonic and neuronal development.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.195-200
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• 1996

In this paper, to eliminate some selected harmonics, we implement PWM inverter which can be able to control in real-time. Using walsh function, which is one of the ordered orthogonal functions, we propose a new method to calculate firing angles, and implement logic circuits which can be calculate firing angles in real-time and be applicable to 1- and 3-phase circuits. Finally, using simulation circuits which accept the outputs obtained from the implemented logic circuits as the inputs, we confirmed the characteristics in steady state of the proposed method for PWM inverter.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.514-520
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• 2015

This paper presents a novel shore-to-sea maritime data transmission system based on time-code diversity, using visible light in maritime environments to overcome the limitations of conventional maritime wireless communications. The proposed system is primarily comprised of existing LED-based lighthouses and maritime transceivers (marine beacons, buoys, etc.), and thus is considered cost-effective in terms of implementation. We first analyze maritime visible-light communications on the basis of the unique properties of a maritime environment, i.e. sea states (wave height, wind speed, etc.), plus atmospheric turbulence, using the Pierson-Moskowitz (PM) and JONSWAP (JS) spectrum models. It is found that the JS model outperforms the PM model, and that the coverage distance depends on the LED power and sea states. To combat maritime fading conditions that significantly degrade performance and coverage distance, we propose a time-code diversity (TCD) scheme in which the delayed versions of the original data are retransmitted using orthogonal Walsh codes. This TCD scheme is found to be superior, in that it offers three orders of magnitude in terms of BER performance, compared to a conventional (non-TCD) transmission scheme. The proposed scheme is robust and efficient in overcoming the effect of impairments present in maritime environments with a BER of approximately $10^{-5}$and a data rate of 100 Kbps at a distance of 1 km.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.92-96
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• 2010

We propose a new satellite OFDMA(Orthogonal Frequency Division Multiple Access) scheme with greatly enhanced tolerance of timing offset among the users. In uplink OFDMA systems, timing misalignment among users destroys subcarrier orthogonality and thus, it degrades the performance. In order to avoid this performance degradation, the accurate processing, so called 'ranging', is required to synchronize among users. However, ranging scheme is not available in the satellite systems due to the very long round trip delay. Exploiting the property that PSW(Propoerly Scrambled Walsh-code) code has zero correlation despite ${\pm}1$ chip timing offset, the proposed OFDMA achieves MAI free performance with the timing offset up to ${\pm}1$ OFDM symbol duration for the satellite systems.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.2
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• pp.1-11
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• 1997

We developed a base station modulator ASIC for CDMA digital cellular system. In CDMA digital cellular system, the modulation is performed by convolutional encoding and QPSK with spread spectrum. The function blocks of base station modulator are CRC, convolutional encoder, interleaver pseudo-moise scrambler, power control bit puncturing, walsh cover, QPSK, gain controller, combiner and multiplexer. Each function block was designed by the logic synthesis of VHDL codes. The VHDL code was described at register transfer level and the size of code is about 8,000 lines. The circuit simulation and logic simulation were performed by COMPASS tools. The chip (ES-C2212B CMB) contains 25,205 gates and 3 Kbit SRAM, and its chip size is 5.25 mm * 5,45 mm in 0.8 mm CMOS cell-based design technology. It is packaged in 68 pin PLCC and the power dissipation at 10MHz is 300 mW at 5V. The ASIC has been fully tested and successfully working on the CDMA base station system.

• Korean Journal of Social Welfare
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• v.47
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• pp.34-70
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• 2001

Little empirical study has been conducted concerning family resilience of family of children with disabilities. The purpose of this study is to examine the variables that may influence the level of family resilience and family resilience level of family of children with disabilities. This study used the sampled of 363 family of children with disabilities selected from 17 community rehabilitation centers. The measurement of family resilience composed of the base of Walsh(1998)'s theory. And using confirmatory factor analysis, it was confirmed that the scale has three factor such as belief system, organizational pattern and communication process. This study showed that using 5 points scale, mean of belief system is 3.62. And mean of organizational pattern is 3.38 and mean of communication process is 3.73. In identifying predictor of the family resilience, this study used variables from the following aspects: perspective of disability of children, intra-aspect of family, extra-aspect of family. Using Regression analysis, it was found that attitude of family of disability and spouse relationship influenced all sub-aspect of family resilience. Specially, helping of professional influenced belief system, accept of disability influenced organizational pattern. And positive expectation of family of disability influenced communication process. This finding give us significant practical implications for social work intervention & the direction of future research in family resilience.

• World Technopolis Review
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• v.3 no.1
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• pp.17-29
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• 2014

The importance of science and technology as the root of exceptional regional economic development has been extolled since the time of Schumpeter. Today emerging technologies are signaling the start of a new economic cycle where regions that are effective in technology translation will gain advantage. The will of policymakers to translate technology into regional job and wealth creation seems to be at an all-time high. Yet an improved process for translating technical development into regional prosperity has proved elusive. If there are no processes other than applying techniques that have worked in the past for other regions to a new region then there is cause for concern. Here the authors seek to add to this field of knowledge by applying elements of the varied cluster theories to provide a basis for policy for regional economic development by turning science and technology into commercial innovation. We provide a review of current cluster theories and discuss the positive and negative issues associated with each. We propose a model that allows interested professionals to utilize aspects of each cluster perspective geared to the realities of their specific area.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.98-105
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• 1989

Various models incorporating Human Visual System (HVS) with the Hadamard transform (HT) represented by Walsh functions are considered. Using the exact frequency components of HT basis functions, the optimum modulation transfer function (MTF) which has a higher peak frequency than DCT schemes is obtimum modulation transfer function (MTF) which has a higher peak frequency than DCT schemes is obtained analytically and visually. The main criterion, for error measurement, is errors at the block boundaries which is an important factor in transform coding. The scheme which has no inverse HVS is proposed. It causes some degradation of image data but it is insignigicant. Crossing area of 4 blocks is equalized by the HVS weighting coefficients. The HVS weighted coding results in perceptually higher quality images compared with the unweighted scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.44-50
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• 2007

In typical MC-CDMA systems, different frequency-domain scrambling codes are randomly chosen from a given code set and then assigned to different subscriber stations using the same subcarrier set. When orthogonal codes are employed for the frequency-domain scrambling, the choice of the scrambling code does not affect the detection performance if the timing and frequency synchronizations are perfect and the channel characteristic is flat. However, in practical cases, inter-code interference often appears due to the broken code orthogonality. In this paper, the optimal order of allocating the orthogonal frequency-domain scrambling codes to new subscriber stations is derived under non-negligible timing offsets in MC-CDMA system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2818-2825
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• 2013

In this paper, a channel estimation method by orthogonalizing of the time domain training signal in MIMO-OFDM systems is proposed. It has shown that Jeon's method[8] cannot be directly used in 4 Tx antenna MIMO-OFDM systems since the delayed Rx signals interfere the orthogonal property of the time domain training signals. As a possible solution to the problem, in this paper, a guard interval is inserted into the center of the training signals so that the orthogonal property between the Rx training signals can be maintained. It is shown by using computer simulations that the proposed method can estimate the channel response in time domain in 4 Tx antenna MIMO-OFDM systems.