• Transactions of the Korean hydrogen and new energy society
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• v.29 no.2
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• pp.219-225
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• 2018

This study was carried out to investigate the injection characteristics of 800 kPa compressed natural gas compressed natural gas (CNG) injector developed in Korea. The CNG injector with multi-holes, employed in this experiment, was designed to inject CNG in the manifold at high pressure of 800 kPa. The spray macroscopic visualization test was carried out via Schlieren photography to study fuel-air mixing process. The fundamental spray characteristics, such as spray penetration, spray cone angle and spray velocity, were evaluated in the constant volume combustion chamber (CVCC) with varying the constant back pressure in CVCC from 0 to 1.8 bar. For the safety reason, nitrogen ($N_2$) and an acetone tracer were utilized as a surrogate gas fuel instead of CNG. The surrogate gas fuel pressures were controlled at 3, 5.5, and 8 bar, respectively. Injection durations were set at 5 ms throughout the experiment. The simulating events of the low engine speed were arranged at 1,000 rpm. The spray images were recorded by using a high-speed camera with a frame rate of 10,000 f/s at $512{\times}256pixels$. The spray characteristics were analyzed by using the image processing (Matlab). The results showed the significant difference that higher injection pressure had more effect on the spray shape than the lower injection pressure. When the injection pressure was increased, the longer spray penetration occurred. Moreover, the linear relation between speed and time are dependent on the injection pressure as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.733-742
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• 2008

In 3GPP LTE downlink system, initial cell search is essential for mobile station to connect to base station. In order to obtain information of the base station, the mobile station detects frame timing, frequency offset, and cell identification using primary synchronization channel(PSC) and secondary synchronization channel(SSC), which are defined in downlink OFDMA specification. In this paper, we analyze various detection algorithms in practical environment of inter-cell-interference, frequency offset, and multi-path fading channel and propose the optimal algorithm. Simulation results show that partial correlation method (for PSC acquisition) and interference cancellation method (for SSC detection) are the most superior algorithms among the applicable algorithms. Employ these two algorithms for receiver design, initial cell search is performed with 99% probability within 70ms in the channel environment considered.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.4
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• pp.80-87
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• 2007

In this paper, link-level performance of a OFDMA technique, which has been considered as a standard for 802.16, 802.20, 3G-LTE, WiMax, and WiBro, is evaluated for next-generation wireless communication systems. While many researches have focused on uncoded forward-link performances, this paper provides a coded performance of a reverse-link OFDMA system. Performance degradation due to time offset among reverse-link users and frequency offset during FFT process is investigated. Transmitter and receiver antenna diversity techniques are used to overcome performance degradation. Performance of a OFDMA system is compared with a CDMA system in terms of FER and throughput to emphasize the advantage of OFDMA system for a reverse-link. Finally, under given specification, Eb/No required to achieve the maximum throughput of a reverse-link is proposed considering various coded rates and antenna permutations.

• BMB Reports
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• v.38 no.5
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• pp.571-576
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• 2005

Cytokines are proteins produced by many different cells of the immune system and play a significant role in initiating and regulating the inflammatory process. In this research, an important cytokine, interleukin-10 (IL-10) gene, has been identified and characterized from zebrafish (Danio rerio) genome database. Zebrafish IL-10 is located within a 2690 bp fragment and contains five exons and four introns, sharing the same organization with mammalian IL-10 genes. An open reading frame of 543 bp was found to encode a putative 180 amino acid protein with a signal peptide of 22 amino acids, which shares 29.7-80.9% homology with amino acid sequences of other known IL-10. The signature motif of IL-10 is also conserved in zebrafish IL-10. The predicted transcript was finally confirmed by sequencing of cDNA clones. Multi-tissue reverse transcriptase PCR (RT-PCR) was performed to examine the tissue distribution and expression regulation of this gene in seven organs of normal and lipopolysaccharide (LPS) stimulation zebrafish. The results demonstrated that this gene was expressed slightly in normal kidney, gill and gut, no expression was detected in other four tissues. The expression was clearly upregulated after LPS stimulation. Using the ideal zebrafish model, further study of IL-10 characterization and function may provide insight on the understanding of the innate immune system.

• Journal of the Korean Society of Costume
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• v.45
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• pp.85-102
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• 1999

The purpose of this study is reviewing and researching the origins of knitwear the history of patterned knits. Aithough historians know little about the origins of knitting many believe it was practiced as early as the 4th century by nomads roaming North Africa. later Arab raders adopted the craft which helped then while away the hours as they traveled across deserts in camel carabans, Its origins lie in the need for close-fitting and elasticated covering for the body in particular the head hand and feet. it first developed in the Mediterranean countries and later in Central and particularly Northern Europe. Early evidence of multicolored knitting is said to date back to the Egyptian Copts of 600-800 A.D. medieval knitting is developed through the Church and monastery. The increasing demand for knitted products already observable in the fourteenth and fifteenth centries and the number of preserved knitted articles increases inexcavated materialos from Europe. The improvements in technique stimulated the developement of the hand knitting industry in the early sixteenth century. The best-known source of production is the guild organization and their mass production consisted of the carpets cushion coverings and other small items for furnishing interiors but mainly of clothing. The demand for knitted goods was such that in the late sixteenth century it was mechanised, The knitting frame invented in 1589 by William Lee English priest was the most perfect machine of this period. The mass production of fully-fashioned and seamless garments in the late nineteenth and twentieth century was dangerously competitve to traditionally woven and sewn cloth in. As fashions changed knitwear has had an almost continuous ruse in public favour and the popularity of sports has encourage the fashion for flexible easy-fitting and absorbent garments.

• Journal of Plant Biotechnology
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• v.7 no.1
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• pp.67-74
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• 2005

To overcome various disadvantages of conventional cul-ture vessels for micropropagation, a novel disposable vessel, the 'Vitron', made of a multi-layered $OTP^{(R)}$ film and supported by a polypropylene frame, was developed. The film possesses superior properties such as: high light transmittance, low water vapor transmittance and thermal stability and in particular, high gas-permeability. Single nodal explants, which were excised from the multiple shoots derived from shoot-tip culture, were cultured in Vitron and polycarbonate vessels on $3\%$ sugar-containing agar on MS medium and placed at 3000 ppm $CO_2$-enrichment at a low photosynthetic photon flux density (PPFD) ($45{\mu}mol\;m^{-2}\;s^{-1}$). The in vitro and ex vitro growth, and the net photosynthetic rate of in vitro and ex vitro plantlets were significantly enhanced in the Vitron compared to those cultured in a polycarbonate vessel. Explants that were cultured on the same MS medium under low PPFD at various $CO_2$ concentrations were also cultured at 3000 ppm $CO_2$- enrichment at various PPFD: 30, 45, 60, 75 and $90{\mu}mol\;m^{-2}\;s^{-1}$. The best in vitro and ex vitro growth obtained for 3000 ppm $CO_2$-enrichment at $75{\mu}mol\;m^{-2}\;s^{-1}$ PPFD. The novel Vitron vessel, when placed under the two conditions, may replace conventional culture vessels for the successful micropropagation of sweetpotato.

• Structural Engineering and Mechanics
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• v.13 no.4
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• pp.369-385
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• 2002

Ductility capacity is comprehensively studied for steel moment-resisting frames. Local, story and global ductility are being considered. An appropriate measure of global ductility is suggested. A time domain nonlinear seismic response algorithm is used to evaluate several definitions of ductility. It is observed that for one-story structures, resembling a single degree of freedom (SDOF) system, all definitions of global ductility seem to give reasonable values. However, for complex structures it may give unreasonable values. It indicates that using SDOF systems to estimate the ductility capacity may be a very crude approximation. For multi degree of freedom (MDOF) systems some definitions may not be appropriate, even though they are used in the profession. Results also indicate that the structural global ductility of 4, commonly used for moment-resisting steel frames, cannot be justified based on this study. The ductility of MDOF structural systems and the corresponding equivalent SDOF systems is studied. The global ductility values are very different for the two representations. The ductility reduction factor $F_{\mu}$ is also estimated. For a given frame, the values of the $F_{\mu}$ parameter significantly vary from one earthquake to another, even though the maximum deformation in terms of the interstory displacement is roughly the same for all earthquakes. This is because the $F_{\mu}$ values depend on the amount of dissipated energy, which in turn depends on the plastic mechanism, formed in the frames as well as on the loading, unloading and reloading process at plastic hinges. Based on the results of this study, the Newmark and Hall procedure to relate the ductility reduction factor and the ductility parameter cannot be justified. The reason for this is that SDOF systems were used to model real frames in these studies. Higher mode effects were neglected and energy dissipation was not explicitly considered. In addition, it is not possible to observe the formation of a collapse mechanism in the equivalent SDOF systems. Therefore, the ductility parameter and the force reduction factor should be estimated by using the MDOF representation.

• Journal of Korean Society of Steel Construction
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• v.13 no.1
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• pp.29-40
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• 2001

Steel frames are increasingly used in commercial buildings. and most steel frames are designed to achieve composite action with the concrete floor slab. The advantages of 'composite construction' are now well understood in terms of structural economy. good performance in service. and ease of construction. But. these conventional composite construction system are difficult to apply steel framed apartment due to their large depth. So. in this study we developed Semi Slim Floor system which could reduce the overall depth of composite beam. Semi Slim Floor system is a method of steel frame multi-story building construction in which the structural depth of each floor is minimised by incorporating the steel floor beams within the depth of the concrete floor slab. Twelve composite slab specimens with different deck-type. slab width. with or without stud bault and concrete topping thickness were tested to evaluate the flexural capacity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.29-34
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• 2008

In this paper, we propose the channel sounding scheme which improves the reliability and performance of communication link and mitigate the fading effect of channel in MTMO-OFDM system having correlation between Tx and Rx antennas. And we estimate the channel propagation characteristics of channels between the transmitter and receiver with CS scheme by measuring the channel propagation characteristics using sounding signal. Multi agent system models can be used to analyze the path of the system within any time frame. Further, using this proposed method, we can increase the channel capacity by simple calculation in receiver and transmitter and allocate the optimal power by channel information in transmitter. Also, the increment of channel capacity using the prorposed method is induced as the number of antenna is increased. So, we can anticipate the performance improvement with the presented scheme in more complicated Tx and Rx antenna system.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.154-161
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• 2015

A novel multiframe super-resolution (SR) algorithm is presented to overcome the limitation of existing single-image SR algorithms using motion information from adjacent frames in a video. The proposed SR algorithm consists of three steps: i) definition of a local region using interframe motion vectors, ii) multiscale patch generation and adaptive selection of multiple optimum patches, and iii) combination of optimum patches for super-resolution. The proposed algorithm increases the accuracy of patch selection using motion information and multiscale patches. Experimental results show that the proposed algorithm performs better than existing patch-based SR algorithms in the sense of both subjective and objective measures including the peak signal-to-noise ratio (PSNR) and structural similarity measure (SSIM).