• The KIPS Transactions:PartB
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• v.16B no.4
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• pp.309-318
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• 2009

The researches on the system that automatically records and retrieves one's everyday life is relatively actively worked recently. These systems, called personal memex or life log, usually entail dedicated devices such as SenseCam in MyLifeBits project. This research paid attention to the digital devices such as mobile phones, credit cards, and digital camera that people use everyday. The system enables a person to store everyday life systematically that are saved in the devices or the deviced-related web pages (e.g., phone records in the cellular phone company) and to refer this quickly later. The data collection agent in the proposed system, called MyMemex, collects the personal life log "web data" using the web services that the web sites provide and stores the web data into the server. The "file data" stored in the off-line digital devices are also loaded into the server. Each of the file data or web data is viewed as a memex event that can be described by 4W1H form. The different types of data in different services are transformed into the memex event data in 4W1H form. The memex event ontology is used in this transform. Users can sign in to the web server of this service to view their life logs in the chronological manner. Users can also search the life logs using keywords. Moreover, the life logs can be viewed as a diary or story style by converting the memex events to sentences. The related memex events are grouped to be displayed as an "episode" by a heuristic identification method. A result with high accuracy has been obtained by the experiment for the episode identification using the real life log data of one of the authors.

• Journal of KIISE:Databases
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• v.33 no.3
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• pp.271-281
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• 2006

Recently the need for Location-Based Service (LBS) has increased due to the development and widespread use of the mobile devices (e.g., PDAs, cellular phones, labtop computers, GPS, and RFID etc). The core technology of LBS is a moving-objects database that stores and manages the positions of moving objects. To search for information quickly, the database needs to contain an index that supports both real-time position tracking and management of large numbers of updates. As a result, the index requires a structure operating in the main memory for real-time processing and requires a technique to migrate part of the index from the main memory to disk storage (or from disk storage to the main memory) to manage large volumes of data. To satisfy these requirements, this paper suggests a unified index scheme unifying the main memory and the disk as well as migration policies for migrating part of the index from the memory to the disk during a restriction in memory space. Migration policy determines a group of nodes, called the migration subtree, and migrates the group as a unit to reduce disk I/O. This method takes advantage of bulk operations and dynamic clustering. The unified index is created by applying various migration policies. This paper measures and compares the performance of the migration policies using experimental evaluation.

• Journal of Digital Contents Society
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• v.15 no.4
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• pp.481-489
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• 2014

In this paper, the automatic standby power blocking socket outlet to reduce standby power by blocking power threshold is implemented. Where, the standby power means a flowing power when a disused power electronic is plugged into the socket outlet. The proposed socket outlet can cut off the standby power by establishing a proper block power threshold electronic device according to each electronic device because it can monitor the amount of power through the smart machines such as the real-time PC or mobile phone and directly control the blocking power threshold. The software is implemented by using Visual Studio software, code vision and SN8 C studio, and the hardware is embodied in ATmega128, SN8F27E93S, USB to UART, and relay etc. Through the simulation, we find that the standby power of the proposed method is similar to that of the conventional method in case of the cellular phone but the standby power of the proposed method is much less than that of the conventional method in case of the computer, air conditioning, and set-top box. Therefore, it is proved that the proposed socket outlet has a superior performance in terms of the standby power.

• Journal of Korea Spatial Information System Society
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• v.8 no.2 s.17
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• pp.53-73
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• 2006

Recently, the need for Location-Based Services (LBS) has increased due to the development of mobile devices, such as PDAs, cellular phones and GPS. As a moving object database that stores and manages the positions of moving objects is the core technology of LBS, the scheme for maintaining the main memory DBMS to the server is necessary to store and process frequent reported positions of moving objects efficiently. However, previous works on a moving object database have studied mostly a disk based moving object index that is not guaranteed to work efficiently in the main memory DBMS because these indexes did not consider characteristics of the main memory. It is necessary to study the main memory index scheme for a moving object database. In this paper, we propose the main memory index scheme based on the R-tree for storing and processing positions of moving objects efficiently in the main memory DBMS. The proposed index scheme, which uses a growing node structure, prevents the splitting cost from increasing by delaying the node splitting when a node overflows. The proposed scheme also improves the search performance by using a MergeAndSplit policy for reducing overlaps between nodes and a LargeDomainNodeSplit policy for reducing a ratio of a domain size occupied by node's MBRs. Our experiments show that the proposed index scheme outperforms the existing index scheme on the maximum 30% for range queries.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.253-264
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• 2002

Recently, hierarchical architectures of databases for location management have been proposed in order to accommodate the increase in user population in future personal communication systems. In particular, a 3-level hierarchical database architecture is compatible with current cellular mobile systems. In the architecture, a newly developed additional databases, regional location database(RLR), are positioned between HLR and VLRs. We propose an efficient cache scheme, called the Double T-thresholds Location Cache Scheme. The cache scheme extends the existing T-threshold location cache scheme which is competent only under 2-level architecture of location databases currently adopted by IS-41 and GSM. The idea behind our scheme is to use two pieces of cache information, VLR and RLR serving called portables. The two pieces are required in order to exploit root only locality of registration area(RA) but also locality of regional registration area(RRA) which is the wide area covered by RLR. We also use two threshold values in order to determine whether the two pieces are obsolete. In order to model the RRA residence time, the branching Eralng-$\infty$ distribution is introduced. Our minute cost analysis shows that the double T-threshold location cache scheme yields significant reduction of network and database costs for molt patterns of portables.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.876-882
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• 2009

In this paper, we propose a sub-cell coverage control algorithm for enhancement of the cell throughput in OFDMA based relay systems. Relay station (RS) is exploited for improved quality of the received signal in cellular communication systems, especially in shadow areas. However, since a RS requires additional radio resource consumption for the link between the base station (BS) and the RS, we have to carefully control the coverage areas if a mobile station (MS) is serviced via the BS or the RS considering the cell throughput. We consider radio resource reuse as well for the sub-cell coverage configuration by applying various reuse patterns between RSs. We also consider a time varying system by adaptively changing the threshold for coverage depending on the MSs' traffic in the cell. We initially determine the sub-cell coverage of the system depending on the ratio of received signal-interference-noise-ratio (SINR) of the MS from the BS and RSs, respectively. Then, the "sub-cell coverage threshold" varies based on the "effective transmitted bits per sub-channel" with time. Simulation result shows that the proposed "time varying coverage control algorithm" leads to throughput improvement compared to the fixed sub-cell coverage configuration.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.4
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• pp.428-435
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• 2004

With the rapid and wide-spread use of cellular telephones much attention has been focussed on propagation in the urban area crowed with buildings and houses. It is often surrounded by hills, forests, and mountains. The importance of surface scattering intereference between transmitters and receivers on the rough surfaces has been interested and investigated. Therefore, a prediction method is necessary to estimate the influence of rough surfaces on microwave radio propagation. Moreover, most of the mobile communications are performed based on the digital communication system rather than the analog one. In this case, we must pay more careful attention to the signal delay caused by the phase delay due to the multi-path propagation. In this paper we have analyzed numerically scattering of electromagnetic waves from building walls by using FVTD(Finite Volume Time Domain) method. We consider three different types of rough surfaces such as periodic, random, and composite structures. We calculate the bistatic normalized radar cross section (NRCS) for horizontal and vertical polarization, and we take account of the conventional optical reflection which corresponds to the n-th Bragg reflection for periodic structures. In addition, we investigated what conditions are needed in order to be able to ignore the higher order Bragg reflection for the periodic structures.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.11-17
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• 2009

The drop impact reliability comes to be important for evaluation of the life time of mobile electronic products such as cellular phone. The drop impact reliability of solder joint is generally affected by the kinds of pad and reflow number, therefore, the reliability evaluation is needed. Drop impact test proposed by JEDEC has been used as a standard method, however, which requires high cost and long time. The drop impact reliability can be indirectly evaluated by using high speed shear test of solder joints. Solder joints formed on 3 kinds of surface finishes OSP (Organic Solderability Preservation), ENIG (Electroless Nickel Immersion Gold) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) was investigated. The shear strength was analysed with the morphology change of intermetallic compound (IMC) layer according to reflow number. The layer thickness of IMC was increased with the increase of reflow number, which resulted in the decrease of the high speed shear strength and impact energy. The order of the high speed shear strength and impact energy was ENEPIG > ENIG > OSP after the 1st reflow, and ENEPIG > OSP > ENIG after 8th reflow.

• Journal of Life Science
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• v.26 no.2
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• pp.265-274
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• 2016

Toxin-antitoxin (TA) systems are ubiquitous genetic modules that are evolutionally conserved in bacteria and archaea. TA systems composed of an intracellular toxin and its antidote (antitoxin) are currently classified into five types. Commonly, activation of toxins under stress conditions inhibits diverse cellular processes and consequently induces cell death or reversible growth inhibition. These effects of toxins play various physiological roles in such as regulation of gene expression, growth control (stress response), programmed cell arrest, persister cells, programmed cell death, phage protection, stabilization of mobile genetic elements or postsegregational killing of plasmid-free cells. Accordingly, bacterial TA systems are commonly considered as stress-responsive genetic modules. However, molecule screening for activation of toxin in TA system is available as development of antimicrobial agents. In addition, cytotoxic effect induced by toxin is used as effective cloning method with antitoxic effect of antitoxin; consequently cells containing cloning vector inserted a target gene can survive and false-positive transformants are removed. Also, TA system is applicable to efficient single protein production in biotechnology industry because toxins that are site-specific ribonuclease inhibit protein synthesis except for target protein. Furthermore, some TA systems that induce apoptosis in eukaryotic cells such as cancer cells or virus-infected cells would have a wide range of applications in eukaryotes, and it will lead to new ways of treating human disease. In this review, we summarize the current knowledge on bacterial TA systems and their applications.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.95-103
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• 2009

In this paper, a generation method of transmit and receive beamforming vectors based on base station cooperation is proposed which maximizes the user SINR in mobile cellular multi-user MIMO systems. There are two main sources of interference which deteriorate the performance of the system, i.e. the inter-user interference caused by the usage of the same radio resource for multiple users in the system, and the inter-cluster interference from neighboring base stations which are not participating in cooperative transmission. The proposed scheme cancels out the inter-user interference by using the block diagonalization(BD) method, and mitigate the inter-cluster interference by using optimal transmit and receive beamforming vectors based on optimal combining(OC) with the statistic information of inter-cluster interference. We perform computer simulations to verify the performance of the proposed scheme, and compare the result to the conventional performance obtained from utilizing the receiver side information only or utilizing the information from neither sides. The performance evaluations are conducted not only over the independent MIMO channels, but over correlated MIMO channels to demonstrate the robustness of the proposed scheme over the channels with correlation among antennas.