• Journal of Radiation Protection and Research
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• v.37 no.4
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• pp.191-196
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• 2012

A double-scattering type Compton camera which is appropriate to imaging a high-energy gamma source has been developed for nuclear material surveillance at Hanyang University. The double-scattering type Compton camera can provide high imaging resolution; however, it has disadvantage of relatively low imaging sensitivity than existing single-scattering type Compton camera. In this study, we introduce a novel concept of a dual-mode Compton camera which incorporates two different types of Compton camera, i.e., single- and double-scattering type. The dual-mode Compton camera can operate high-resolution mode and high-sensitivity mode in a single system. To maximize its performance, the geometrical configuration was optimized by using Geant4 Monte Carlo simulation toolkit. In terms of imaging sensitivity, high-sensitivity mode had higher sensitivity than high-resolution mode up to 100 times while high imaging resolution of the double-scattering Compton camera was maintained.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1073-1077
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• 2003

The Sn $O_2$-based gas sensors can detect inflammable and toxic gases of low concentration by the modulation of surface resistance, but they lack in selectivity on the whole. To give selectivity to the Sn $O_2$-based gas sensors, studies on the sensing mechanism, selective gas sensing materials and signal processing techniques are demanded. Ethanol (C$_2$ $H_{5}$OH) and acetonitrile ($CH_3$CN) were confirmed to undergo catalytic oxidation on Sn $O_2$ by gas chromatography. PdCl$_2$-doped Sn $O_2$ showed excellent sensitivity to ethanol and acetonitrile, while La$_2$ $O_3$-doped Sn $O_2$ showed excellent sensitivity to ethanol, but poor sensitivity to acetonitrile. Using these two sensors and pattern recognition, the selectivity to acetonitrile is greatly enhanced. The minimum detection level of acetonitrile was 15 ppm in air and 20 to 100 ppm when exposed to interfering gases together with acetonitrile.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.5
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• pp.1077-1084
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• 2015

Security issues such as an illegal acquisition of personal information and identity theft happen due to using game bots in online games. Game bots collect items and money unfairly, so in-game contents are rapidly depleted, and honest users feel deprived. It causes a downturn in the game market. In this paper, we defined the growth types by analyzing the growth processes of users with actual game data. We proposed the framework that classify hard-core users and game bots in the growth patterns. We applied the framework in the actual data. As a result, we classified five growth types and detected game bots from hard-core users with 93% precision. Earlier studies show that hard-core users are also detected as a bot. We clearly separated game bots and hard-core users before full growth.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1415-1425
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• 2018

MMORPG genre is based on the belief that all users in virtual world are equal. All users are able to obtain the corresponding wealth or status as they strive under the same resource, time. However, game bot is the main factor for harming this fair competition, causing benign gamers to feel a relative deprivation and deviate from the game. Game bots mainly form GFG(Gold Farming Group), which collects the goods in the game indiscriminately and adversely affects the economic system of the game. A general game bot detection algorithm is useful for detecting each bot, but it only covers few portions of GFG, not the whole, so it needs a wider range of detecting method. In this paper, we propose a method of detecting GFG based on items used in MMORPG genre. Several items that are mainly traded in the game were selected and the flows of those items were represented by a network. We Identified the characteristics of exchanging items of GFG bots and can identify the GFG's item trade network with real datasets from one of the popular online games.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.145-151
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• 2024

Recently, ship hull-mounted passive sonar system solution is needed in the perspective of improving target detection and elimination of vibration-induced noise. Our research team suggests acousticvibration matching method using front and rear signal of a sensor as the improvement of the problem above. Thus in this paper, theoretical background about matching method and its application on finite element method based multi-physics simulation are described. Furthermore, it is shown that target detection and hull vibration performance are improved by using matching method under the condition of our sensor system. Finally, practicality and future research are discussed.

• Review of KIISC
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• v.15 no.1
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• pp.23-32
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• 2005

기업 활동에서 인터넷과 정보통신 시스템에 대한 의존도가 점차 심화됨에 따라 보안사고의 발생시 기업이 감당해야 할 사업적 위험도 함께 증대하고 있다. 따라서 최근 다양한 사이버 공격의 징후를 조기에 감지하고 대응함으로써 피해범위를 최소화할 수 있는 조기경보 체계의 구축에 많은 기업들이 관심을 갖기 시작했다. 하지만 조기경보 체계의 구축과 운용을 위해서는 비용과 기술적인 장애를 극복해야 한다. 본 논문은 대부분의 기업들이 네트워크에서 실시간 위협탐지를 위해 사용하는 네트워크 침입탐지 시스템(N-IDS)과 정기적인 보안감사용으로 주로 운영하는 취약점분석 시스템(VAS)을 이용하여 경제적이고, 효과적으로 사이버 공격의 징후를 신속하게 파악할 수 있는 조기경보 시스템의 설계방법을 제시하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.590-593
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• 2022

최근 코로나바이러스감염증-19(COVID-19)로 인해서 다양한 비대면 서비스가 증가하고 있는데 그 중에서 사람과 인공지능 간 의사소통하여 정보를 얻는 대화 시스템이 대표적인 서비스이다. 대화 시스템은 입력되는 단일 문장에 대한 정보만을 응답하기 때문에 이전 대화의 정보를 알기 위해서는 질문했던 내용을 다시 입력해야 하는 문제점이 있다. 이런 문제를 해결하고 대화 진행에 도움을 주기 위해서 본 논문에서는 대화 내 문장들의 다중 의도 탐지를 통한 공통 대화 주제 식별 시스템을 제안한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.208-211
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• 2021

본 논문에서는 합성곱 신경망을 활용하여 영상에서 마스크 착용 및 미착용 상태를 탐지하는 방법을 제안한다. 코로나바이러스감염증-19(COVID-19)의 유행에 따라 감염 및 확산방지를 위해 마스크 정상적 착용이 요구되는데 몇몇 사람들은 이를 지키지 않고 있으며 현재의 감시 시스템은 입구에서 마스크 착용 여부를 검사하는 방식으로 작동될 뿐 공간에 입장한 다음 착용 여부를 알 수 없다. 제안하는 방법은 합성곱 신경망을 통해 영상에서 얼굴을 탐지하여 얻은 데이터를 이용하여 다수사람들의 마스크 착용 및 미착용 상태를 판별하는 방법으로 설계하였다.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.419-424
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• 1997

It is well known that the metallo-phthalocyanines (MPcs) are sensitive to toxic gaseous molecules such as NO$_2$ as well as are chemically and thermally stable. Therefore, lots of MPcs have been studied as the potential chemical sensor for NO$_2$gas using quartz crystal microbalance(QCM) or electrical conductivity. In this study, thin films of octa(2-ethylhexyloxy)copper-phthalocyanine were prepared by Langmuir-Blodgett method and characterized by using UV-VIS absorption spectroscopy and ellipsometry. Optimal transfer condition of LB films was investigated and preliminary results of current-voltage(I-V) characteristics of these films exposed to NO$_2$gas as a function of film thickness, temperature and concentration were discussed.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.175-179
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• 2010

본 논문에서는 주소형화재감지기의 필요성을 확인하고자 기존 일반형감지기의 회로분석 및 문제점을 통해 한계성을 분석하여, 화재 및 비화재보시 자동화재탐지설비의 성능향상을 위해 일반형감지기에 주소기능을 부여한 주소발생 및 주소수신모듈을 설계 제작하였고, 작동테스트를 통해 주소형감지기의 필요성을 알리고자 한다.