• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1774-1784
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• 1993

This paper presents the design, fabrication and measured results of the broadband microstrip array with a conical radiation pattern and the circular array composed of six square microstrip antenna elements. Each element antenna has the stacked structure with a parasitic element to achieve a broadband characteristic and a branch line quadrature hybrid is attached to it for the circular polarization. The design procedures and measured results of the scheme for obtaining the conical radiation pattern which is useful for the mobile communication via the satellite. Finally, the performance of the fabricated antenna is measured and compared with the theory.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.11_12
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• pp.557-565
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• 2005

This paper presents the development and implementation of a zero-copy file transfer mechanism that improves the efficiency of file transfers for PC cluster systems using hardware-based VIA(Virtual Interface Architecture) network adapters. VIA is one of the representative user-level communication interfaces, but because there is no library for file transfer, one copy occurs between kernel buffer and user boilers. Our mechanism presents a file transfer primitive that does not require the file system to be modified and allows the NIC to transfer data from the kernel buffer to the remote node directly without copying. To do this, we have developed a hardware-based VIA network adapter, which supports the PCI 64bit/66MHz bus and Gigabit Ethernet, as a NIC, and implemented a zero-copy file transfer mechanism. The experimental results show that the overhead of data coy and context switching in the sender is greatly reduced and the CPU utilization of the sender is reduced to $30\%\~40\%$ of the VIA send/receive mechanism. We demonstrate the performance of the zero-copy file transfer mechanism experimentally. and compare the results with those from existing file transfer mechanisms.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.511-514
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• 2015

A pretreatment process of cellulose decomposition to a monosaccharide plays an important role in the cellulosic ethanol production using the lignocellulosic biomass. In this study, a cellulosic ethanol was produced by using acidic hydrolysis and enzymatic saccharification process from the lignocellulosic biomass such as rice straw, sawdust, copying paper and newspaper. Three different pretreatment processes were compared; the acidic hydrolysis ($100^{\circ}C$, 1 h) using 10~30 wt% of sulfuric acid, the enzymatic saccharification (30 min) using celluclast ($55^{\circ}C$, pH = 5.0), AMG ($60^{\circ}C$, pH = 4.5), and spirizyme ($60^{\circ}C$, pH = 4.2) and also the hybrid process (enzymatic saccharification after acidic hydrolysis). The yield of cellulosic ethanol conversion with those pretreatment processes were obtained as the following order : hybrid process > acidic hydrolysis > enzymatic saccharification. The optimum fermentation time was proven to be two days in this work. The yield of cellulosic ethanol conversion using celluclast after the acidic hydrolysis with 20 wt% sulfuric acid were obtained as the following order : sawdust > rice straw > copying paper > newspaper when conducting enzymatic saccharification.

• Fire Science and Engineering
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• v.27 no.6
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• pp.50-56
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• 2013

The radiation effects on the auto-ignition and extinction characteristics of a non-premixed fuel-air counterflow field were numerically investigated. A detailed reaction mechanism of GRI-v3.0 was used for the calculation of chemical reactions and the optically-thin radiation model was adopted in the simulations. The flame-controlling continuation method was also used in the simulation to predict the auto-ignition point and extinction limits precisely. As a result, it was found that the maximum H radical concentration, $(Y_H)_{max}$, rather than the maximum temperature was suitable to understand the ignition and extinction behaviors. S-, C- and O-curves, which were well known from the previous theory, were identified by investigating the $(Y_H)_{max}$. The radiative heat loss fraction ($f_r$) and spatially-integrated heat release rate (IHRR) were introduced to grasp each extinction mechanism. It was also found that the $f_r$ was the highest at the radiative extinction limit. At the flame stretch extinction limit, the flame was extinguished due to the conductive heat loss which attributed to the high strain rate although the heat release rate was the highest. The radiation affected on the radiative extinction limit and auto-ignition point considerably, however the effect on the flame stretch extinction limit was negligible. A stable flame regime defined by the region between each extinction limit became wide with increasing the fuel temperature.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.696-705
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• 2002

This paper presents a new copy network for multicast ATM switches. Many studies have been carried out up to date since the proposition of Lee's copy network. However, the overflows and cell conflicts within the switch have still been raised a problem in argument. In order to reduce those problems, we proposed a 3-dimensional multicast switching architecture which has shared buffers in this paper. The proposed architecture can reduce the overflows and cell conflicts through multiple paths and output ports even in the high load environments. Also, we proposed a cell splitting algorithm which handles the cell in the case of large fan-out, and a copy network to increase throughput by expanding the Lee's Broadcast Banyan Network(BBN). Cell copy uses the Boolean interval splitting algorithm and the multicast pattern of the cells according to the self-routing characteristics of the network. In the proposed copy network, we improve the problems such as overflow, cell splitting of large fanout, cell conflicts, etc., which were still existed in the Lee's network. The results of performance evaluation by computer simulation show that the proposed scheme has better throughput, cell loss rate and cell delay than the conventional method.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.3
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• pp.66-80
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• 2012

It is necessary to normalize spectral image values derived from multi-temporal satellite data to a common scale in order to apply remote sensing methods for change detection, disaster mapping, crop monitoring and etc. There are two main approaches: absolute radiometric normalization and relative radiometric normalization. This study focuses on the multi-temporal satellite image processing by the use of relative radiometric normalization. Three scenes of KOMPSAT-2 imagery were processed using the Multivariate Alteration Detection(MAD) method, which has a particular advantage of selecting PIFs(Pseudo Invariant Features) automatically by canonical correlation analysis. The scenes were then applied to detect disaster areas over Sendai, Japan, which was hit by a tsunami on 11 March 2011. The case study showed that the automatic extraction of changed areas after the tsunami using relatively normalized satellite data via the MAD method was done within a high accuracy level. In addition, the relative normalization of multi-temporal satellite imagery produced better results to rapidly map disaster-affected areas with an increased confidence level.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.468-474
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• 2002

In this paper a novel two-arm microstrip spiral antenna with a circular slot on the ground plane is presented. The proposed antenna structure is constructed in a planar form without a balun circuit and the radiation characteristics of conventional and eccentric spiral antennas are obtained simultaneously. The main beam direction is normal to the plane of the spiral for characteristic frequency band and the direction of the main beam moves linearly into $\theta$ and $\phi$ direction as the frequency increases.

• Journal of KIISE
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• v.42 no.6
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• pp.699-706
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• 2015

In recent years, as near-duplicate image has been increasing explosively by the spread of Internet and image-editing technology that allows easy access to image contents, related research has been done briskly. However, BoF (Bag-of-Feature), the most frequently used method for near-duplicate image detection, can cause problems that distinguish the same features from different features or the different features from same features in the quantization process of approximating a high-level local features to low-level. Therefore, a post-verification method for BoF is required to overcome the limitation of vector quantization. In this paper, we proposed and analyzed the performance of a post-verification method for BoF, which converts SIFT (Scale Invariant Feature Transform) descriptors into 128 bits binary codes and compares binary distance regarding of a short ranked list by BoF using the codes. Through an experiment using 1500 original images, it was shown that the near-duplicate detection accuracy was improved by approximately 4% over the previous BoF method.

• Journal of the Korean Society for information Management
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• v.31 no.3
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• pp.89-110
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• 2014

In this study, we analyzed KERIS Document Delivery Service (DDS) using its transaction data for the period of nine years from 2004 to 2012. We first examined the overall statistics focusing on member contributions, and conducted a network analysis based on the records of request/response (supply) between member libraries. Key findings include the following: First, in over 80% of member libraries, the number of outgoing requests exceeded the number of their responses to incoming requests. That is, for the vast majority of member libraries, their participation was concentrated on the request side. Second, KERIS DDS relies heavily on a relatively small number of top contributors, especially on the supply side. While the top contributors were active in both requests and responses (supplies), in most cases, they received and processed a disproportionally large number of requests. Third, the network analysis based on DDS requests for journal articles in 2012 further revealed the central role of top contributors. The level and pattern of concentration, however, appeared to differ by subjects (DDC). Three main patterns of centralization were found in different subjects - a network centered on a single member, a network having multiple centers, or a distributed network.

• Journal of Advanced Navigation Technology
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• v.12 no.2
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• pp.180-190
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• 2008

There have been researches into digital Watermarking technology or Fingerprinting vigorously to safeguard Protective rights for knowledge and poverty for digital contents. DRM(Digital Rights Management) is not only Protective rights for knowledge and poverty, but also management and systems that are necessary to put out, circulate and use for contents. This paper proposes two kinds of ideas. One is protecting contents from illegal acts such as illegal copies when the contents are in the process of circulation. The other is the protocol that can give users convenience. Hidden Agents are used so that contents are protected from illegal copies and illegal use in the contents and cuts off those illegal acts. The Agent will be installed without any special setup. In addition, it can replace roles of Watermarking as a protection. Therefore, this paper shows the solution of illegal copies that happens frequently.