• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1581-1587
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• 2004

In this paper, We have proposed an Heterodyne technique to generate millimeter-wave signal. Microwave signals in cellular broadband mobile communication networks and distributed networks can favorably be generated and distributed by optical techniques. In principle, these techniques have already been investigated for optical control of phase-array antennas, characterization of photo-detector and phase locking of millimeter-wave oscillators and now being applied to wireless communications. The generation and transmission of millimeter-wave radio signals by optical means is of interest for future pico-cell broadband mobile communication system, especially for systems operating at frequencies of 300Hz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2769-2774
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• 2010

In this paper, we have proposed sideband injection locking method, heterodyne technique, to generate millimeter-wave signal. Microwave signals in cellular broadband mobile communication networks and distributed networks can favorably be generated and distributed by optical techniques. In principle, these techniques have already been investigated for optical control of phase-array antennas, characterization of photo-detector and phase locking of millimeter-wave oscillators and now being applied to wireless communications. The generation and transmission of millimeter-wave radio signals by optical means is of interest for future pico-cell broadband mobile communication system, especially for systems operating at frequencies of tens of GHz applicable to LMDS. We experimented and analysed the generation of millimeter wave signal.

• Journal of Power Electronics
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• v.9 no.4
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• pp.631-642
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• 2009

The sun is a useful reference direction because of its brightness relative to other astronomical objects and its relatively small apparent radius as viewed by spacecrafts near the Earth. Most satellites use solar power as a source of energy, and so need to make sure that solar panels are oriented correctly with respect to the sun. Also, some satellites have sensitive instruments that must not be exposed to direct sunlight. For all these reasons, sun sensors are important components in spacecraft attitude determination and control systems. To minimize components and structural mass, some components have multiple purposes. The solar cells will provide power and also be used as coarse sun sensors. A coarse Sun sensor is a low-cost attitude determination sensor suitable for a wide range of space missions. The sensor measures the sun angle in two orthogonal axes. The Sun sensor measures the sun angle in both azimuth and elevation. This paper presents the development of a model to determine the attitude of a small cube-shaped satellite in space relative to the sun's direction. This sensor helps small cube-shaped Pico satellites to perform accurate attitude determination without requiring additional hardware.

• Journal of Acupuncture Research
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• v.22 no.2
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• pp.133-139
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• 2005

Cobrotoxin, a venom of Vipera lebetina turanica, is a group of basic peptidescomposed of 233 amino acids with six disulfide bonds formed by twelve cysteins. NF-kB is activated by subsequent release of inhibitory IkB and translocation of p50. Since sulfhydryl group is present in kinase domain of p50 subunit of NF-kB, cobrotoxin could modify NF-kB activity by protein-protein interaction. We therefore examined effect of cobrotoxin on NF-kB activities in lipopolysaccharide (LPS) and sodium nitroprusside (SNP)-stimulated Raw 264.7 mouse macrophages. Cobrotoxin suppressed the LPS and SNP-induced release of IkB and p50 translocation resulted in inhibition of DNA binding activity of NF-kB. Inhibition of NF-kB resulted in reduction of the LPS and SNP-induced production of inflammatory mediators NO and PGE2 generation. The inhibitory effect of cobrotoxin on the NF-kB activity were blocked by addition of reducing agents dithiothreitol and glutathione. These results demonstrate that cobrotoxin inhibits activation of NF-kB, and suggest that pico to nanomolar range of cobrotoxin could inhibit the expression of genes in the NF-kB signal pathway.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.36-40
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• 2010

Ballast water has been known as a major vector for global dispersal of toxic dinoflagellates and other microalgae. In this study, biodiversity in ships’ ballast water was examined using a dinoflagellate-oriented PCR primer set and species-specific real-time PCR. While motile dinoflagellates could be observe at very low cell densities by light microscopy,a wide range of dinoflagellate taxa including parasitic and phototrophic pico-dinoflagellates as well as harmful species to marine fish/shellfish was detected when techniques for cloning/sequencing of SSU rDNA of sample cells were used. Present result suggests that molecular methods including species-specific PCR primers may offer rapid and accurate detection of invasive species in ballast water.

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.403-412
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• 2003

Temporal and spatial variations of size-structured phytoplankton (chlorophyll a) were investigated over an annual cycle (February-October, 2003) to elucidate phytoplankton dynamics in the Juam Reservoir, Chonnam. Physical properties were also measured to investigate the relationship between the properties and temporal and spatial variations of size structured phytoplankton using simple linear regression. Phytoplankton (chlorophyll a) were grouped into three size classes: micro-size(> 20 ${\mu}m$), nano-size (3-20 ${\mu}m$) and pico-size (< 3 ${\mu}m$) in this study. Physical properties included water temperature, light attenuation coefficients, PAR (photosynthetically active radiation) and turbidity. Maximum chlorophyll a was observed in April, 2003 in the lower region whereas a peak of chlorophyll a developed in October, 2003 in the upper region. Large cell-sized phytoplankton (micro-size class)were dominant in the events of the chlorophyll a peaks. Potential mechanisms in the physical properties affecting the size-structured phytoplankton dynamics in the Juam Reservoir were discussed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.3
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• pp.248-262
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• 2021

Marine planktonic ciliates include two major groups, loricated tintinnids and naked oligotrichs. The study of marine ciliate plankton in Korea began with taxonomic efforts on tintinnids based on the morphology of lorica, a vase-shaped shell. Despite polymorphism in the lorica, it is utilized as a key characteristic in identification of tintinnid species. However, oligotrichs have been studied only recently in Korea due to challenges associated with the observation of ciliary arrangements and the technical development for cell staining. Species diversity and phylogenetic classification of the ciliates have been informed by recent advances in morphological and molecular analyses. Illustrations of the planktonic ciliate in Korea have been published on the basis of taxonomic data of tintinnids and oligotrichs. Planktonic ciliates acting as the major consumers of pico- and nanoplankton as well as the prey of mesozooplankton, has been monitored by spatial and temporal investigations in Korean coastal waters. A practical approach addressing the limitations and potential of marine ciliate studies in Korea is proposed here to improve the data quality of planktonic ciliates, providing an enhanced basis for quality control of ciliate monitoring.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4A
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• pp.471-480
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• 2000

With the limited wireless resources, various traffic in the cellular system is served based on micro-cell or pico-cell structure. The rapid increase in the number of mobile users results in the frequent handoff which is becoming a critical issue. In this paper, we propose a channel allocation scheme to reduce the probability of handoff failure. In this scheme, we provide a guard channel for each service to handle the handoff processes. It maintains the low probability of failure in handoff calls. To prevent the performance degradation due to the traffic variation, we use a channel arbitration method that adaptively manages the number of channels based on the call density. We evaluated the performance in terms of the initial call blocking probability and the handoff call blocking probability for various traffic and motility. We found that the proposed scheme keeps the lower probability of call blocking through the efficient channel arbitration than other suggested methods even for the irregular traffic conditions.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.879-894
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• 2016

In micro-fluid systems, fluids are injected into extremely narrow polymer channels in small amounts such as micro-, nano-, or pico-liter scales. These channels themselves are embedded on tiny chips. Various specialized structures in the chips including pumps, valves, and channels allow the chips to accept different types of fluids to be entered the channel and along with flowing through the channels, exert their effects in the framework of different reactions. The chips are generally crystal, silicon, or elastomer in texture. These highly organized structures are equipped with discharging channels through which products as well as wastes of the reactions are secreted out. A particular advantage regarding the use of fluids in micro-scales over macro-scales lies in the fact that these fluids are much better processed in the chips when they applied as micro-scales. When the laboratory is miniaturized as a microchip and solutions are injected on a micro-scale, this combination makes a specialized construction referred to as "lab-on-chip". Taken together, micro-fluids are among the novel technologies which further than declining the costs; enhancing the test repeatability, sensitivity, accuracy, and speed; are emerged as widespread technology in laboratory diagnosis. They can be utilized for monitoring a wide spectrum of biological disorders including different types of cancers. When these microchips are used for cancer monitoring, circulatory tumor cells play a fundamental role.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.2
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• pp.68-74
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• 2011

Objective: Previously, we found that oocyte specific homeobox (Obox) 4 plays significant role in completion of meiosis specifically at meiosis I-meiosis II (MI-MII) transition. The purpose of this study was to determine the mechanism of action of $Obox4$ in oocyte maturation by evaluating downstream signal networking. Methods: The $Obox4$ dsRNA was prepared by $in$ $vitro$ transcription and microinjected into the cytoplasm of germinal vesicle oocytes followed by $in$ $vitro$ maturation in the presence or absence of 0.2 mM 3-isobutyl-1-metyl-xanthine. Total RNA was extracted from 200 oocytes of each group using a PicoPure RNA isolation kit then amplified two-rounds. The probe hybridization and data analysis were used by Affymetrix Gene-Chip$^{(R)}$ Mouse Genome 430 2.0 array and GenPlex 3.0 (ISTECH, Korea) software, respectively. Results: Total 424 genes were up (n=80) and down (n=344) regulated after $Obox4$ RNA interference (RNAi). Genes mainly related to metabolic pathways and mitogen-activated protein kinase (MAPK) signaling pathway was changed. Among the protein kinase C (PKC) isoforms, PKC-alpha, beta, gamma were down-regulated and especially the MAPK signaling pathway PKC-gamma was dramatically decreased by $Obox4$ RNAi. In the cell cycle pathway, we evaluated the expression of genes involved in regulation of chromosome separation, and found that these genes were down-regulated. It may cause the aberrant chromosome segregation during MI-MII transition. Conclusion: From the results of this study, it is concluded that $Obox4$ is important upstream regulator of the PKC and anaphase-promoting complex action for maintaining intact germinal vesicle.