• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.85-93
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• 2007

This paper presents new LVDS I/O circuits with a high noise margin for use in highly parallel I/O environments. The proposed LVDS I/O includes transmitter and receiver parts. The transmitter circuits consist of a differential phase splitter and a output stage with common mode feedback(CMFB). The differential phase splitter generates a pair of differential signals which have a balanced duty cycle and $180^{\circ}$ phase difference over a wide supply voltage variation due to SSO(simultaneous switching output) noises. The CMFB output stage produces the required constant output current and maintains the required VCM(common mode voltage) within ${\pm}$0.1V tolerance without external circuits in a SSO environment. The proposed receiver circuits in this paper utilizes a three-stage structure(single-ended differential amp., common source amp., output stage) to accurately receive high-speed signals. The receiver part employs a very wide common mode input range differential amplifier(VCDA). As a result, the receiver improves the immunities for the common mode noise and for the supply voltage difference, represented by Vgdp, between the transmitter and receiver sides. Also, the receiver produces a rail-to-rail, full swing output voltage with a balanced duty cycle(50% ${\pm}$ 3%) without external circuits in a SSO environment, which enables correct data recovery. The proposed LVDS I/O circuits have been designed and simulated with 0.18um TSMC library using H-SPICE.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.121-126
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• 2006

This paper report on the design and implementation of a 9.6kbps DSSS CDMA modem for a medium speed wireless link. The proposed modem provides a general purpose I/O interface with a microprocessor. The I/O interface consists of 8-bit data bus, chip enable, read/write, and interrupt pins. In transmit block, the 8-bit data delivered from the I/O interface buffer is converted to 9.6kbps serial data, which are spreaded into 76.8kcps with 8-bit PN code generated inside the modem by direct sequence method. An 8-bit training sequence is preceded in the data frame for data synchronization in receiver. In receiver block the PN code is synchronized from the received data spreaded to 76.8kcps and find the data timing from the 8-bit training sequence. We have used the Early-and-Late integration method. The modem has been implemented and verified using a Xilix FPGA board and has been fabricated as an ASIC CHIP through Hynir $0.25{\mu}m$ CMOS. The multiple accessing method is DSSS CDMA.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.579-582
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• 2007

최근 들어 더욱 UCC(User Created Contents)등과 같은 대용량 멀티미디어(multimedia) 서비스에 대한 요구가 나날이 증가되면서 부하분산에 중점을 둔 웹 클러스터링 시스템(Web Clustering System) 에서 기존의 작은 크기의 스트림 데이터(Stream Data)나 조금 더 다양한 데이터를 위한 읽기 성능을 대용량 데이터에 초점을 맞춘 방안으로 최적화 시키는 것이 중요시되고 있다. 본 논문에서는 대용량 멀티미디어를 중심으로 실제 서비스시 간과 되어질 수 있는 운영체제(Operating System, O/S)에서의 I/O 인식, 디스크 제어 프로그램에서의 I/O, 웹 클러스터의 부하분산정책의 파라미터(Parameter)를 개선함으로써 읽기성능 향상 방안을 제시한다.

• Journal of Computing Science and Engineering
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• v.3 no.1
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• pp.15-26
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• 2009

Given an n-length text T over a $\sigma$-size alphabet, we present a compressed representation of T which supports retrieving queries of rank/select/access and updating queries of insert/delete. For a measure of compression, we use the empirical entropy H(T), which defines a lower bound nH(T) bits for any algorithm to compress T of n log $\sigma$ bits. Our representation takes this entropy bound of T, i.e., nH(T) $\leq$ n log $\sigma$ bits, and an additional bits less than the text size, i.e., o(n log $\sigma$) + O(n) bits. In compressed space of nH(T) + o(n log $\sigma$) + O(n) bits, our representation supports O(log n) time queries for a log n-size alphabet and its extension provides O(($1+\frac{{\log}\;{\sigma}}{{\log}\;{\log}\;n}$) log n) time queries for a $\sigma$-size alphabet.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.157-163
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• 2017

The binary and interpolation search algorithms are the most famous among search area algorithms, the former running in $O(log_2n)$ on average, and the latter in $O(log_2log_2n)$ on average and O(n) at worst. Also, the interpolation search use only the probability of key value location without priori information. This paper proposes another search algorithm, which I term a 'hybrid block and interpolation search'. This algorithm employs the block search, a method by which MSB index of a data is determined as a block, and the interpolation search to find the exact location of the key. The proposed algorithm reduces the search range with priori information and search the reduced range with uninformed situation. Experimental results show that the algorithm has a time complexity of $O(log_2log_2n_i)$, $n_i{\simeq}0.1n$ both on average and at worst through utilization of previously acquired information on the block search. The proposed algorithm has proved to be approximately 10 times faster than the interpolation search on average.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.10
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• pp.121-127
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• 2009

This paper reviews a basic data of the surface discharge characteristics for tefton resin in not only pure $N_2$, $N_2:O_2$(80[%]:20[%], I-Air) and $N_2:O_2$(60[%]:40[%]) mixture gas as environment-friendly insulation Gas also $SF_6$. Used electrodes are Knife to Knife. With the changing distance of electrodes and pressure, we can find it, surface discharge voltages and surface dielectric strengths, respectively. Surface discharge Voltages of I-Air are more higher than the other $N_2/O_2$ mixture gases. Moreover, we can obtain that the surface dielectric strengths of $SF_6$ are two times about I-Air, approximately.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.657-668
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• 2008

Traditional off-the-shelf file server has several potential drawbacks to store data blocks. A first drawback is a lack of practical de-duplication consideration for storing data blocks, which leads to worse storage capacity waste. Second drawback is the requirement for high performance computer system for processing large data blocks. To address these problems, this paper proposes a clustering backup system that exploits file fingerprinting mechanism for block-level de-duplication. Our approach differs from the traditional file server systems in two ways. First, we avoid the data redundancy by multi-level file fingerprints technology which enables us to use storage capacity efficiently. Second, we applied a cluster technology to I/O subsystem, which effectively reduces data I/O time and network bandwidth usage. Experimental results show that the requirement for storage capacity and the I/O performance is noticeably improved.

• Journal of Astronomy and Space Sciences
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• v.25 no.1
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• pp.25-32
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• 2008

Using the solar wind data of 2000 observed by ACE, We classified the interplanetary shock on basis of shock driver. We examined the physical properties of shock drivers such as the ratio of charge states(O7/O6) and thermal index$(I_{th})$. Most of 51 interplanetary shocks are driven by interplanetary coronal mass ejections(ICME; magnetic cloud and ejecta) and high speed streams. According to the test of temperature(O7/O6) and $I_{th}$, we found that ICMEs originated from region with hot source in corona.

• Proceedings of the KSRS Conference
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• v.1
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• pp.196-199
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• 2006

Various communication mechanisms have been developed to acquire a meaningful data from sensors. The key requirement during the sensor data acquisition is determinism and reduction of time dependency. It is a fundermental level of satellite data management for controlling satellite operation software data acquisition from sensors or subsystem. Satellite operation software has various software modules to be operated in addition to data acquisition. Therefore, unnecessary time delay shall be minimized to perform the data acquisition. As the result, interrupt method might be prefered than polling method because the former can decrease the restriction of design during implementation of data acquisition logic. The possible problems while using interrupt method like as interrupt latency caused by delaying of interrupt processing time are analyzed. In this paper, communication mechanism which can be used to interface with satellite computer and subsidary subsystem by using interrupt is presented. As well, time dependency between software scheduling and data acquisition is analyzed.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.267-267
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• 2004