• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.469-472
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• 2007

최근 많은 광대역 유무선 통신 응용분야에서 OFDM(Orthogonal Frequency Division Multiplexing) 방식을 표준기술로 채택하고 있다 OFDM 방식의 고속 무선 데이터 통신를 위한 FFT 프로세서는 일반적으로 DSP(Digital Signal Processing)로 구현되었으나, 큰 전력 소비를 필요로 한다. OFDM의 단점인 전력문제를 보안하기 위해서 Current-mode FFT LSI가 제안되었다. 본 논문에서는 Current-mode FFT LSI의 구현을 위한 저전력 IVC를 설계하였다. 설계된 IVC는 FFT Block의 출력이 $13.65{\mu}A$ 이상일 때에 3V 이상의 전압을 출력하고, FFT Block의 출력이 $0.15{\mu}A$ 이하일 때에 0.5V 이하의 전압을 출력한다. 그리고 IVC의 총 소모전력은 약 1.65mW이다. $0.35{\mu}A$ 공정에서의 저전력 IVC를 설계함으로서, $0.35{\mu}A$ 공정에서의 Current-mode FFT LSI의 설계가 가능해졌다. 저전력 OFDM 통신용 Current-mode FFT LSI는 무선통신의 발전에 기여할 것으로 전망한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1613-1619
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• 2004

Turbo codes of long block sizes have been known to show very good performance in an AWGN channel and the turbo code has been strongly recommended as error correction code for W-CDMA in 3GPP(3rd Generation Partnership Project). Recently, turbo codes of short block sizes suitable for real time communication systems have attracted a lot of attention. Thus, in this paper we consider the turbo code of 1/3 code rate and short frame size of 192 bits in ITU-R channel model. We analyzed the performance of W-CDMA systems of 10MHz bandwidths employing RAKE receiver with not only MRC diversity but also SOVA-based turbo code.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.254-254
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• 2006

The sensitivity of plasmid DNA (pDNA) to S1 nuclease, an enzyme to cleave a single-strand DNA, was dramatically modulated through a supramolecular assembly (polyion complex micelle) with a synthetic block copolymer, poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL). The pDNA condensed in stoichiometric charge ratio was cleaved into 7 fragments each being 10/12, 9/12, 8/12, 6/12, 4/12, 3/12, and 2/12 of the original DNA length, on the other hand, the pDNA condensed in higher charge ratios (>4), were digested into non-specific manner. Condensation of the pDNA was investigated from two viewpoints that how does the rigid DNA molecules fold and condense and how does the condensation influence their biological activity.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.33-43
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• 2016

In order to analyze ground relaxation and cavity formation mechanism due to deteriorated sewer pipe, field test was carried out and a numerical assessments were compared with the field test results. An artificial underground cavity was intended using the ice block overlaying the buried pipe and confirmed that the cavity and relaxation of the surrounding ground were gradually formed as the ice block starts to melt down. Such mechanism was highly suspected to be involved with soil particle interlocking as a soil compaction was a typical process for the buried pipes. In exploring such mechanism numerically, commercially available DEM (Discrete Element Method) code PFC2D was used and the interlocking induced cavern behaviors were successfully simulated and compared with field test results by utilizing the clump logic imbedded in PFC code.

• Parasites, Hosts and Diseases
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• v.52 no.4
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• pp.439-441
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• 2014

Toxoplasma gondii is the causative agent of toxoplasmosis with symptoms of congenital neurological and ocular diseases and acquired lymphadenitis, retinochoroiditis, and meningoencephalitis. Small molecules which block the activity of protein kinases were tested in in vitro culture of T. gondii to find new therapeutic drugs of safer and more effective than the combined administration of pyrimethamine and sulfadoxine that sometimes provoke lethal Stevens-Johnson syndrome. Among them, Gefitinib and Crizotinib inhibited intracellular growth of T. gondii in HeLa cells by counting the number of T. gondii per parasitophorous vacuolar membrane whereas Sunitinib did not. Gefitinib inhibited the growth of T. gondii in a dose-dependent manner over $5{\mu}M$ up to the tolerable concentration of HeLa cells and halted the division of the parasite immediately from the time point of treatment. Gefitinib inhibition suggests that tyrosine kinases of EGFR family or other homologous kinases of the parasite itself may be the target to cause the block of T. gondii growth.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3103-3120
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• 2015

This paper presents a single-phase energy metering chip with built-in calibration function to measure electric power quantities. The entire chip consists of an analog front end, a filter block, a computation engine, a calibration engine, and an external interface block. The key design issues are how to reduce the implementation costs of the computation engine from repeatedly used arithmetic operations and how to simplify calibration procedure and reduce calibration time. The proposed energy metering chip simplifies the computation engine using time-division multiplexed arithmetic units. It also provides a simple and fast calibration scheme by using integrated digital calibration functionality. The chip is fabricated with 0.18-μm six-layer metal CMOS process and housed in a 32-pin quad-flat no-leads (QFN) package. It operates at a clock speed of 4096 kHz and consumes 9.84 mW in 3.3 V supply.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.177-185
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• 2019

In this paper, we propose and evaluate a FDE combined with STBC transmission structure to cancellation of ISI in underwater acoustic communication. To achieve this purpose, underwater acoustic channels are modeled and the simulation results are presented. In case of STBC-FDE, the transmission rate is less about 4% than STBC-OFDM, but the SER performance is better than STBC-OFDM that is larger from 4.4% to 16.8% at the SNR of 15dB than STBC-OFDM.

• Geosciences Journal
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• v.23 no.4
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• pp.547-556
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• 2019

A new species of the most primitive rosenellid stromatoporoid Cystostroma, C. primordia sp. nov. is reported from the Hunghuayuan Formation (Lower Ordovician, Floian) of Guizhou Province in the South China Block and the Duwibong Formation (Middle Ordovician, Darriwilian) of the Taebaeksan Basin in mid-eastern Korea (North China Block). This species is the first representative of the genus found in both the North and South China blocks. Cystostroma primordia sp. nov. is characterized by the absence of denticles and distinctively smaller cyst plates (height 0.04-0.20 mm, length 0.09-0.39 mm) than any other known species of Cystostroma. The presence of C. primordia sp. nov. in Lower to Middle Ordovician strata of western Gondwana challenges the long-held view of the late Middle Ordovician emergence of Paleozoic stromatoporoids. The simple internal morphological features of this new species and its occurrence in the Lower Ordovician of South China strongly indicate that an Early Ordovician Cystostroma-type precursor from western Gondwana is located near the base of the stromatoporoid stock. This occurrence greatly preceded the late Middle Ordovician (late Darriwilian) stromatoporoid diversification in circum-equatorial regions worldwide.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1805-1815
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• 2019

While nickel-based alloys have been widely used for power plants due to corrosion resistance and good mechanical properties, during the last couple of decades, failures of nuclear components increased gradually. One of main degradation mechanisms was primary water stress corrosion cracking at dissimilar metal welds of piping and reactor head penetrations. In this context, precise estimation of welding effects became an important issue for ensuring reliability of them. The present study deals with a series of finite element analyses and crack growth rate evaluation of Alloys 690/152. Firstly, variation of residual stresses and equivalent plastic strains was simulated taking into account welding of a cylindrical block. Subsequently, extraction and pre-cracking of compact tension (CT) specimens were considered from different locations of the block. Finally, crack growth curves of the alloys and heat affected zone were developed based on analyses results combined with experimental data in references. Characteristics of crack growth behaviors were also discussed in relation to mechanical and fracture parameters.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.407-415
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• 2022

In this study, a square rounding sidewalk block frame was developed considering the simplicity of construction and the superiority of aesthetics. In addition, it is possible to prevent damage, deformation, and settlement of adjacent sidewalk blocks due to plastic deformation during car impact load of installed bollad. A non-linear structural analysis was performed through finite element analysis to examine the performance of a car crash to which this was applied. Structural safety was confirmed through car crash simulation according to the direction of impact, and it is estimated that the function can be restored by replacing some parts in case of damage due to impact.