• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.481-484
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• 2003

OFDM(Orthogonall Frequency Division Multiplexing) is an efficient transmission techniques for the frequency selective fading wireless channel where conventional modulations suffer from severe performance degradation. Recently, more efficient techniques for the OFDM are paid much attention such as adaptive modulation for each subcarrier, since more bit rate has been required for the wireless data network [1-3]. The proposed system employs the adaptive modulation between transmitter and receiver in each subcarrier, where the bit and power is properly allocated. Also multiple antenna system called MIMO is considered, which result in robustness in channel delay, improved power efficiency and improved bit SNR for the given BER.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.100-103
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• 2008

COMS(Communication, Ocean and Meteorological Satellite) has multiple payloads; Meteorological Image(MI), Ocean Color Imager(GOCI) and Ka-band communication payloads. MI has 4 IR and 1 visible channel. In order to improve the quality of IR image, two calibration sources are used; black body image and cold space look data. In case of COMS, the space look is performed at 10.4 degree away from the nadir in east/west direction. During space look, SUN or moon intrusions are strictly forbidden, because it would degrade the quality of collected IR channel calibration data. Therefore we shall pay attention to select space look side depending on SUN and moon location. This paper proposes and discusses a simple and complete space look side selection logic based on SUN and moon intrusion event file. Computer simulation has been performed to analyze the performance of the proposed algorithm in term of east/west angular distance between space look position and hazardous intrusion sources; SUN and moon.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.472-473
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• 2008

Flow boiling in parallel microchannels has received attention as an effective heat sink mechanism for power-densities encountered in microelectronic equipment. the bubble dynamics coupled with boiling heat transfer in microchannels is still not well understood due to the technological difficulties in obtaining detailed measurements of microscale two-phase flows. In this study, complete numerical simulation is performed to further clarify the dynamics of flow boiling in microchannels. The level set method for tracking the liquid-vapor interface is modified to include the effects of phase change and contact angle. The method is further extended to treat the no-slip and contact angle conditions on the immersed solid. Also, the reverse flow observed during flow boiling in parallel microchannels has been investigated. Based on the numerical results, the effects of channel shape and inlet area restriction on the bubble growth, reverse flow and heat transfer are quantified.

• International Commerce and Information Review
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• v.7 no.1
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• pp.75-94
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• 2005

With most major full service banks having launched transactional Internet banking, attention is shifting to the realities of managing the Internet channel as a profitable component of an overall delivery strategy. In addition to examining Case Study and Internet Bank Model. Services of Internet Banking available through the Internet are as follows. 1. credit card loans, personal loans. 2. high-yield financial products. 3. insurance products. 4. securities products. 5. Case study of Foreign Internet Banking(ING, BNP, HSNC, City Bank). The study reviewed fields, including financial services, customer service, Website formation and design, convenience of use and system safety, Internet Banking Model, and many related areas. Internet Banking earned high marks in most fields. This study review focuses on the following: Understanding and meeting consumer expectations for us ability, site performance and functionality. Integrating the Internet channel into overall marketing, product delivery and customer service strategies. Strategies to increase customer satisfaction with Internet Banking and to attract new Internet bankers. therefore this study review activity model concretion of Internet Banking Model and Case Study.

• Journal of Communications and Networks
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• v.9 no.2
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• pp.150-158
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• 2007

We consider channel-coded multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) transmission and obtain a condition on its signal for it to attain the maximum diversity and coding gain. As this condition may not be realizable, we propose a suboptimal design that employs an orthogonal transform and a space-frequency interleaver between the channel coder and the multi-antenna OFDM transmitter. We propose a corresponding receiving method based on block turbo equalization. Attention is paid to some detailed design of the transmitter and the receiver to curtail the computational complexity and yet deliver good performance. Simulation results demonstrate that the proposed transmission technique can outperform the conventional coded MIMO OFDM and the MIMO block single-carrier transmission with cyclic prefixing.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.88-93
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• 2019

This study explores one of charity drive contents on YouTube channel. Due to the advance of science and technology, ordinary people come to make their own video content online, usually via YouTube. YouTube becomes number one online video storage/streaming platform, and many people upload their own video and they get attention and fame. This study analyzes various aspects of Shoot for Love, soccer-based charity drive videos shown on YouTube channel created in South Korea. Unlike popular videos in YouTube, Shoot for Love centers on charity by casting popular soccer players and celebrities. Especially, this study researches 1) Components 2) Traits of Components 3) Contents of Components in Shoot for Love. Throughout this, it not only analyzes unique aspects of Shoot for Love that show how and why YouTube content matters, but also suggest plausible methods to drive charity and institution are suggested that appeal to the public.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.188.2-188.2
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• 2003

Large-conductance $Ca^{2+}$ activated potassium channels $(BK_{ca})$ are widely distributed and play key roles in various cell functions. In nerve cells, B $K_{ca}$ channels shorten the duration of action potentials and block $Ca^{2+}$ entry thereby repolarizing excitable cells after excitation. $(BK_{ca})$ channel opening has been postulated to confer neuroprotection during stroke and has attracted attention as a means for therapeutic intervention in asthma, hypertension, convulsion, and traumatic brain injury. (omitted)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2305-2315
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• 2015

Frequency resource value is growing more and more with the development of the wireless communication. With the advent of the current information society comes a serious shortage of frequency resource, as the amount of supply is far from meeting its demands. Thus, cognitive radio (CR) technique is receiving more attention as a way to make use of the temporarily unoccupied frequency resource. In this paper we propose a novel out-of-band spectrum sensing and dynamic channel access scheme for frequency hopping-based cognitive radio ad-hoc networks. At the beginning of each current channel hopping time, member nodes perform spectrum sensing for the next hopping channel. Based on the proposed collision free primary detection notification, member nodes can determine whether they should execute a hopping time extension procedure of the current channel or not. When the primary detected hopping channel is re-idled, the hopping pattern recovery procedure is performed. In this paper we evaluated the performance of the proposed dynamic sensing and hopping channel extension mechanism for the various wireless network conditions. As a result, we show that the proposed method can increase channel utilization and provide reliable channel management operation.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.60-66
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• 2014

Most tidal current turbine designs are focused on medium and large scale for deep sea, less attention is paid in low water level channel, such as the region around the islands and costal sea. This study is to develop a horizontal axis tidal current turbine rotor blade which is applicable to low water level island region in southwest coastal region of Korea. In this study, the hydrofoil NACA63-415 and NACA63-817 are both adopted to analyze. The blade using NACA63-817 showed the higher maximum power coefficient and good performance at small TSR (Tip Speed Ratio), which gives the blade more advantages in operating at lower water level channel, where is characterized by the fast-flowing water. The cavitation pattern of hydrofoil is predicted by the CFD analysis and verified that the NACA63-817 is the appropriate hydrofoil in the test site of tidal current resource and the hydrofoil showed considerable performance in avoiding cavitation.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.242-242
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• 2012

Transparent oxide semiconductors are increasingly becoming one of good candidates for high efficient channel materials of thin film transistors (TFTs) in large-area display industries. Compare to the conventional hydrogenated amorphous silicon channel layers, solution processed ZnO-TFTs can be simply fabricated at low temperature by just using a spin coating method without vacuum deposition, thus providing low manufacturing cost. Furthermore, solution based oxide TFT exhibits excellent transparency and enables to apply flexible devices. For this reason, this process has been attracting much attention as one fabrication method for oxide channel layer in thin-film transistors (TFTs). But, poor electrical characteristic of these solution based oxide materials still remains one of issuable problems due to oxygen vacancy formed by breaking weak chemical bonds during fabrication. These electrical properties are expected due to the generation of a large number of conducting carriers, resulting in huge electron scattering effect. Therefore, we study a novel technique to effectively improve the electron mobility by applying environmental annealing treatments with various gases to the solution based Li-doped ZnO TFTs. This technique was systematically designed to vary a different lithium ratio in order to confirm the electrical tendency of Li-doped ZnO TFTs. The observations of Scanning Electron Microscopy, Atomic Force Microscopy, and X-ray Photoelectron Spectroscopy were performed to investigate structural properties and elemental composition of our samples. In addition, I-V characteristics were carried out by using Keithley 4,200-Semiconductor Characterization System (4,200-SCS) with 4-probe system.