• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.61-68
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• 2015

Recently, with increasing use of smartphones, the security threats also have increased rapidly. Especially, the compromised smartphone is very dangerous because it could be exploited in a DDOS attacks such as cyberterrorism as well as in the leakage of personal information. However, most bot detection mechanisms are still unsuitable for smartphone with its lower computing capability and limited battery capacity because they incur additional computational overheads or require pre-defined signatures. In this paper, we present an efficient bot detection mechanism in smartphones. Our mechanism detects effectively bots in outgoing traffic by using a correlation between user events and network traffic. We have implemented its prototype in Android smartphone and measured its performance. The evaluation results show that our mechanism provides low overhead to detect bots in smartphones.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.767-774
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• 2013

The electricity demand and supply could be off balance if several electric vehicles(EVs) were charged at the same time or at peak load times. Therefore, smart grids are necessary to flatten the EVs' electricity demand and to enable EVs to be used as distributed storage devices as electricity demand from EV-charging increases. There are still few quantitative studies on the impact of smart grids on managing EVs' electrical loads. In this study, we analyzed the quantitative impact of smart grids on managing EVs' electrical loads and suggested policy implications. As a result, it is identified that smart grids can manage effectively EVs' impact on electrical grids. The electricity market structure and regulatory framework should support the demonstration and commercialization of smart grid technologies.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.797-802
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• 2020

Over the past few years, smart devices, including smartphones, have been continuously required by users based on portability. The performance is improving. Ubiquitous computing environment and sensor network are also improved. Due to various network connection technologies, mobile terminals are widely used. Smart terminals need technology to make energy monitoring more detailed for more stable operation during use. The smart terminal which is light in small size generates the power shortage problem due to the various multimedia task among the terminal operation. Various estimation hardwares have been developed to prevent such situation in advance and to operate stable terminals. However, the method and performance of estimating the remaining amount are not relatively good. In this paper, we propose a method for estimating the remaining amount of smart terminals. The Capacity Estimation of lithium ion cells for stable operation was estimated based on machine learning. Learning the characteristics of lithium ion cells in use, not the existing hardware estimation method, through a map learning algorithm using machine learning technique The optimized results are estimated and applied.

• Journal of KIISE
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• v.42 no.8
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• pp.1031-1038
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• 2015

The recent emergence of smart phones, wearable devices, and even the IoT concept made it possible for various objects to interact one another anytime and anywhere. Among many of such smart services, a smart home service typically requires a large number of sensors to recognize the residents' activities. For this reason, the ideas on activity recognition using the data obtained from those sensors are actively discussed and studied these days. Furthermore, plenty of sensors are installed in order to recognize activities and analyze their patterns via data mining techniques. However, if many of these sensors should be installed for IoT smart home service, it raises the issue of cost and energy consumption. In this paper, we proposed a new method for reducing the number of sensors for activity recognition in a smart environment, which utilizes the principal component analysis and clustering techniques, and also show the effect of improvement in terms of the activity recognition by the proposed method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.6
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• pp.1375-1391
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• 2012

Smart grid is a next-generation intelligent power grid that applying ICT to power grid to maximize the energy efficiency ratio. Recently, technologies and standards for smart grid are being developed around the world. Information security which is an essential part of smart grid development has to be managed continuously. Information security management system certification for organizational risk management has been implemented in Korea. Although preparation for information security management system certification which is applicable to smart grid is considered, there are no specific methods. This paper is to propose core and added evaluation criteria for Korean smart grid based on K-ISMS through comparative analysis between ISMS operated in Korea and smart grid information security management system developed in the United States. Added evaluation criteria enable smart grid related business that certified existing ISMS to minimize redundant and unnecessary certification assessment work.

• Electronics and Telecommunications Trends
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• v.24 no.6
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• pp.11-21
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• 2009

에너지를 절약하고 제품을 축소하기 위하여 전력공급 장치나 전력변환 장치에 사용되는 전력반도체는 전력용 파워스위칭 소자와 제어 IC로 구성되어 전력을 시스템에 맞게 배분하는 제어와 변환기능을 가진 반도체로 단순히 전력을 조절하고 전달하는 역할에서 에너지효율 제고 및 시스템 안정성과 신뢰성을 좌우하는 역할로 확장되어 가고 있고, 교토의정서 등의 지구 온난화 방지노력과 글로벌 환경규제의 확대로 친환경 절전형 부품/시스템 개발이 절실히 요구되는 실정이다. 이에 따라, 본 고에서는 스마트환경, 그린에너지, 예방진단 등 미래 인간생활 대응을 통해 신기술 및 신시장을 창출하는 신성장 동력 분야인 저전력, 고효율, 저발열, 저소음 등 환경 친화적으로 동작하여 에너지 효율 및 $CO_2$ 배출에 직접적인 영향을 미치는 친환경 절전형 전력반도체 기술 동향에 대해 논의하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.123-125
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• 2018

본 논문은 블록체인 알고리즘을 탑재한 HEMS 시스템을 활용하여 전력의 생산과 소비를 동시에 수행하는 에너지 프로슈머들 간의 안전하고 신뢰성 있는 전력거래 시스템을 구현하기 위한 방안을 연구하였다. 신재생발전원의 가정내 보급이 증대하고 HEMS를 통해 댁내 에너지관리가 보다 스마트해지고 전력정보의 실시간 취득이 가능해짐에 따라 동일 변대주 인근 배전선로와 연결된 에너지 프로슈머들간의 소규모 전력거래에 있어 블록체인 기반 기술 적용이 보다 용이해 질 것으로 예상된다. 또한, HEMS를 활용하여 블록체인 기반 P2P간의 전력거래에 있어 기술적 한계를 극복하기 위한 추가적인 연구 방향을 함께 제시하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.1075-1078
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• 2021

우리나라의 1인당 전력 소비량이 가파르게 증가하고 있으며 이에 따른 에너지 절약의 필요성이 대두되고 있다. 본 논문은 IoT 기술을 활용하여 더욱 간단하고 효율적인 저비용 에너지 절약 시스템을 제안한다. 실시간 모니터링과 센서 데이터를 기반으로 한 에너지 절약 시나리오 제공이 큰 특징이다. 구현한 시스템은 전력 사용량 peak 값과 전체적인 편차가 줄어드는 결과를 가져왔다. 더 나아가 가정뿐만 아니라 더 넓은 범위에 적용 가능할 것으로 기대된다.

• Smart Media Journal
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• v.6 no.4
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• pp.24-31
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• 2017

In wireless sensor networks, sensor nodes are deployed in a remote, harsh environment. When the power of the sensor node is consumed in such a network, the sensor nodes become useless together with the deterioration of the quality and performance of the sensor network which may save human life. Although many clustering protocols have been proposed to improve the energy consumption and extend the life of the sensor network, most of the previous studies have shown that the overhead of the cluster head is quite large. It is important to design a routing protocol that minimizes the energy consumption of each node and maximizes the network lifetime because of the power limitations of the sensor nodes and the overhead of the cluster heads. Therefore, in this paper, we propose an efficient clustering scheme that reduces the burden of cluster heads, minimizes energy consumption, and uses algorithms that maximize network lifetime. Simulation results show that the proposed clustering scheme improves the energy balance and prolongs the network life when compared with similar techniques.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.1
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• pp.14-22
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• 2021

Drilling equipment is an essential part used in various fields such as construction, mining, etc., and it has drawn increasing attention in recent years. The drilling method is generally divided into three types. There are a top hammer method that strikes on the ground, a DTH (Down-The-Hole) method that directly strikes a bit in an underground area, and a rotary method that drills by using rotational force. Among them, the DTH method is most commonly used because it enables efficient drilling compared to other drilling methods. In the conventional DTH hammer, the valve between the piston and the bit is opened and closed using a face to face method. In order to improve the power of the DTH hammer, a DTH hammer with foot valve which is capable of instantaneous opening and closing is used in the drilling field. In this study, we designed a lab-scale DTH hammer with the foot valve, and manufactured an evaluation device for the experiment of the DTH hammer. In addition, we analyzed the performance of the DTH hammer adopted with foot valve according to the pressure range of 3-10 bar. As a result, the internal pressure distribution in the DTH hammer was experimentally analyzed, and then, the movement of the piston according to the pressure was predicted. We believe that this study provides the useful results to explain the performance characteristics of the DTH hammer with the foot valve.