• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.115-131
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• 2008

Small mobile devices have become commonplace in our everyday life, from cellular phones to PDAs. Discovering dense regions for the mobile devices is one of the problems of grate practical importance. It can be used in monitoring movement of vehicles, concentration of troops, etc. In this paper, we propose a novel algorithm on continuously clustering a large set of mobile objects. We assume that a mobile object reports its position only if it is too far away from the expected position and thus the location data received may be imprecise. To compute the location of each individual object could be costly especially when the number of objects is large. To reduce the complexity of the computation, we want to first cluster objects that are in proximity into a group and treat the members in a group indistinguishable. Each individual object will be examined only when the inaccuracy causes ambiguity in the final results. We conduct extensive experiments on various data sets and analyze the sensitivity and scalability of our algorithms.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.2 s.16
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• pp.117-127
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• 2000

The economic development and the development of medical treatment by scientific technology development progressed the level of national people life and improved average life gradually. In this reason, old people who have finance power would like to receive a comport and high level service, though paying proper expense. In this study, receiving this requirement, we focused that silver town have reasonable and comfortable residing environment in developing rural and rest form silver town objecting external area of Chon-Ju city, and selected land suitability. Through the learning of the neural network theory in the method of land suitability, we applied in the full of study area and improved a flexible determination making as giving each class value in each cell. Also, we compare a method of land suitability using the neural network theory, and it's analysis with a method of land suitability by the duplication method of Boolean Logic have been used In Geo Spatial Information System(GSIS) and proved the Boolean Logic's lose of values and the propriety.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.64.1-64.1
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• 2016

YAM (Young Astronomers Meeting, 젊은 천문학자들의 모임)과 We Love Galaxies는 인적/학문적 네트워크가 중요시되는 시대의 흐름에 발맞춰 국내 천문학 전공 대학원생들을 위한 워크샵인 "2016 YAM & We Love Galaxies 공동 워크샵"을 강촌에서 개최하였습니다. 2016년 2월 24일부터 26일까지 2박 3일간 개최된 이번 워크샵에는 총 35명의 대학원생/학부생/박사후연구원이 참가하였고, 전원 포스터 발표를 통해 참여 학생 모두가 자신의 연구주제를 자유롭게 소개하고 교류할 수 있도록 하였습니다. 뿐만 아니라 대학원 생활 및 연구 활동에 관련된 9개의 주제를 가지고 조별 토론을 진행하였습니다. 본 발표에서는 "2016 YAM & We Love Galaxies 공동 워크샵" 의 성과와 학생들로부터 받은 피드백을 소개하고 대학원생 워크샵이 나아가야 할 방향에 대해 제시하고자 합니다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.10
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• pp.941-944
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• 2016

This paper proposes 24 GHz power amplifier for automotive collision avoidance and surveillance short range radar using Samsung 65-nm CMOS process. The proposed circuit has a 2-stage differential power amplifier which includes common source structure and transformer for single to differential conversion, impedance matching, and power combining. The measurement results show 15.5 dB maximum voltage gain and 3.6 GHz 3 dB bandwidth. The measured maximum output power is 13.1 dBm, input $P1_{dB}$ is -4.72 dBm, output $P1_{dB}$ is 9.78 dBm, and maximum power efficiency is 17.7 %. The power amplifier consumes 74 mW DC power from 1.2 V supply voltage.

• Journal of Digital Forensics
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• v.12 no.3
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• pp.9-17
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• 2018

Smartphone have become commonplace because they have the advantage of facilitating communication with others and making life easier. The smartphone's system log stores various data related to the user actions. Since 2015, Huawei has been growing rapidly, with its sales volume increasing and it was ranked second in the world in three years. The use of Huawei smartphones by many users means that Huawei smartphones are likely to be used to detect traces of criminal investigations, so we need to study system logs of Huawei smartphones. Therefore, in this paper, we analyze system log which is forensically meaningful for Huawei smartphone. We also propose how to use logs in forensic investigation.

• Korean Security Journal
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• no.10
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• pp.387-407
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• 2005

Thanks to the developments of IT technologies, such critical infrastructures as fundamental structures of energies, material circulations, monetary circulations, and living necessaries are intertwined as well as mutually dependent. In this respect, the fact that national infrastructures are closely related to IT infrastructures implies not only expected benefits to provide diverse information-based services, but also anticipated costs to bring about new dangers. However, in spite of these threats, traditional researchers have not put enough interests in these indirect danger, which yield the damages in broad areas through paralyzing risk management systems, although they have investigated such direct threats as nuclear accidents, conflagrations, traffic troubles, and gasoline accidents. Considering that the tendency to depend on electricity, so-called electrification, which is caused by automation and informationalization, is intensified in all parts of society, the breakout problem as a factor to inhibit securities in information-oriented society is significant. Thus, the problems of large-scale power blackout should be treated as national crises. Also, preparation systems for large-scale power blackout have to be provided quickly. In this paper, with analyzing various cases of large-scale power blackout and investigation the causes of them, researches on the blackout management systems of Korea are to be present, on the basis of national crisis management states which are comprised of protection (mitigating and preparing), responding, and recovering(rewarding).

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.2
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• pp.104-111
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• 2008

The ECG is biomedical electrical signal occurring on the surface of the body due to the contraction and relaxation of the heart. This signal represents an extremely important measure for health monitoring, as it provides vital information about a patient's cardiac condition and general health. ECG signals are contaminated with high frequency noise such as power line interference, muscle artifact and low frequency nose such as motion artifact. But it is difficult to filter nose from ECG signal, and errors resulting from filtering can distort a ECG signal. The present study implemented a small-size and low-power ECG measurement system that can remove motion artifact for convenient health monitoring during daily life. The implemented ECG monitoring system consists of ECG amplifier, a low power microprocessor, bluetooth module and monitoring program. Amplifier was designed and implemented using low power instrumentation amplifier, and microprocessor was interfaced to the ECG amplifier to collect the data, process, store and feed to a transmitter. And bluetooth module used to wirelessly transmit and receive the vital sign data from the microprocessor to an PC at the receiving site. In order to evaluate the performance of the implemented system, we assessed motion artifact rejection performance in each situation with artificially set condition using adaptive filter.

• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.137-144
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• 2004

ECG signals are often contaminated with high-frequency noise such as muscle artifact, power line interference, and others. In the ECG signal processing, especially during a pre-processing stage, numerous noise removal techniques have been used to reduce these high-frequency noise without much distorting the original signal. This paper proposes a new type of digital filter with a continuously variable cutoff frequency to improve the signal quality This filter consists of a cutoff frequency controller (CFC) and variable cutoff frequency lowpass filter (VCF-LPF). From the noisy input ECG signal, CFC produces a cutoff frequency control signal using the signal slew rate. We implemented VCF-LPF based on two new filter design methods called convex combination filter (CCF) and weight interpolation fille. (WIF). These two methods allow us to change the cutoff frequency of a lowpass filter In an arbitrary fine step. VCF-LPF shows an excellent noise reduction capability for the entire time segment of ECG excluding the rising and falling edge of a very sharp QRS complex. We found VCF-LPF very useful and practical for better signal visualization and probably for better ECG interpretation. We expect this new digital filter will find its applications especially in a home health management system where the measured ECG signals are easily contaminated with high-frequency noises .

• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.85-90
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• 2017

The purpose of this study is to investigate the effect of vertical and horizontal refraction on the lower part of the power supply and control system of various facilities and machinery that use electricity, so that the power distribution system, which is an important electric facility installed in buildings and public facilities, Type earthquake resistant pads to protect the substructure and prevent short-circuiting on the upper part of the system. The GR-63-CORE (Scale 8.3 class) It is earthquake disaster prevention and disaster prevention technology that satisfies seismic performance. As a research result, it is possible to protect the electricity and communication infrastructure, which can contribute to shortening the time for recovering the electric facilities to the normal state in case of an earthquake, and preventing the fire caused by the destruction of the electricity supply facility in case of an earthquake. As a result, it is possible to minimize the spread of fire that occurs when a large-scale earthquake occurs and to minimize the damage of people and damage to property, and it can contribute to the securing of electric infrastructure that enables citizens to quickly recover to daily life even after suffering a major earthquake. In addition, the technology can be applied to ensure the seismic resistance of the equipment in the communication and computer room, and it can be applied to various fields where the facility function can be stopped due to the shaking of the earthquake base.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.2
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• pp.37-45
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• 2012

Byeolseo was located in various places with beautiful natural scenery to avoid the mundane world and for country life in seclusion. In this study, to classify locational type and characteristics of Byeolseo in Gyeongsangnamdo and Jeollado areas, complex locational types and characteristics of total 96 Byeolseo (52 in Gyeongsangnamdo and 44 in Jeollado) were researched and cluster analysis was executed to group locational characteristics to several clusters with similar characteristics in order to classify locational types of Byeolseo. As the result, locational type for Gyeongangnam-do and Jeolla-do were classified to 5 types each. Unique locational types Gyeongsangnamdo were 'valley type' and 'cliff type' and unique ones for Jeollado were 'flatland type' and 'riverside.hill type'. 'Hill type', 'curvy river type' and 'riverside other type' were shown in both areas. In Gyeongangnamdo, 30.8% was cliff type and 15.4% was valley type 46.2% of the total was locatedon 'cliff near river' or 'valley'. These were the most popular locational characteristics of Gyeongangnamdo. Unlike Gyeongangnamdo, 18.2% was flatland type, 18.2% is riverside.hill type, and 39.6% was hill type in Jeollado 75.0% of the total was locatedon 'flatland', 'on hill near river' or 'on hils'. These were the most popular locational characteristics of Jeollado. Such locational characteristics showed that Byeolseo was located using nearby scenery considering topographic characteristics of the located area.