• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.677-680
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• 2004

In the mobile environment, according to the movement of the object, the query finds the nearest special object or place from object position. However, because query object moves continuously in the mobile environment, query demand changes according to the direction attribute of query object. Also, in the case of moving of query object and simply the minimum distance value of query result, sometimes we find the result against the query object direction. Especially, in most road condition, as user has to return after reaching U-turn area, user rather spends time and cost. Therefore, in order to solve those problems, in this paper we propose the nearest neighbor method considering moving object position and direction for mobile recommendation system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.209-210
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• 2008

고부가 서비스용 수용가 통합자원관리 시스템에 관련된 국내외 표준에 대해 조사하였다. 국가 표준은 KSC 부문이 있고, 국제 표준은 주로 IEC가 제정한 것이다. 그밖에 여러 국제 표준화 기구가 있지만 고부가 서비스용 수용가 통합자원관리 시스템 개발에 적용될 수 있는 국제 표준을 찾을 수는 없었다. 그래서 고부가 서비스용 수용가 통합자원관리 시스템을 개발하는 과정에서 필요하다고 생각되는 표준이 국내외 표준으로 제안되는 것이 좋겠다. 제안되는 표준안이 국내외에서 표준으로 채택된다면 다양한 기술 개발안이 연구되며 경쟁함으로써 빚어지는 연구역량의 낭비를 줄이고, 기술의 진보 방향을 우리나라에서 주도함으로써 미래 기술 영역을 선점하는 효과를 기대할 수 있을 것이다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.189-190
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• 2015

본 논문은 배터리에너지저장장치(BESS)를 적용하여 전력계통의 2차 주파수조정 보조서비스를 제공하기 위한 제어 방안을 검토한다. BESS가 계통운영기관의 자동발전제어를 통한 2차 주파수조정 보조서비스에 참여하기 위해서는 제어 요구량에 대한 정확한 추종이 가능 해야하고 이를 위한 효율적인 SOC 관리가 요구된다. 이를 위해 본 논문에서는 2차 주파수조정 보조서비스 제어신호를 제어대상 배터리의 SOC에 따라 배분하고 SOC가 가용범위를 벗어 날 경우 SOC 회복제어를 수행하도록 제어 방안을 제안하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.629-630
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• 2015

본 논문에서는 소규모 에너지저장장치를 주파수조정 서비스에 활용하기 위한 클러스터링 기법을 제안하였다. 다양한 클러스터링 기법에서 에너지저장장치에 적합한 기법을 선정하고 적합도 산정방법을 통하여 수명비용을 최소화 하는 방향으로 충 방전하는 기법을 제안하였다. 사례연구에서는 무작위로 에너지저장장치를 운영하는 방법과 제안한 방법의 비교를 통하여 제안한 기법의 효과를 입증하였다.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.606-613
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• 2012

In a smart grid environment, data for the usage and control of power are transmitted over an Internet protocol (IP)-based network. This data contains very sensitive information about the user or energy service provider (ESP); hence, measures must be taken to prevent data manipulation. Mutual authentication between devices, which can prevent impersonation attacks by verifying the counterpart's identity, is a necessary process for secure communication. However, it is difficult to apply existing signature-based authentication in a smart grid system because smart meters, a component of such systems, are resource-constrained devices. In this paper, we consider a smart meter and propose an efficient mutual authentication protocol. The proposed protocol uses a matrix-based homomorphic hash that can decrease the amount of computations in a smart meter. To prove this, we analyze the protocol's security and performance.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1172-1177
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• 2006

Effective management strategies of railroad environment should be prepared by the systematic management with the environment core technologies from the initial stage of the railroad environment to provide energy-efficient, safe, sound, and environment-friendly railroad service. In addition, the need for the development of railroad environment policy, like the improvement strategies and development strategies of railroad environment, is strongly required to actively prepare for the strengthening of environment regulations and supervision on the railroad environment problems. In this research, we studied the correlations between railroad environment policies and management strategies, and defined the component of environment policies. Moreover, we tried to present the direction of environment policies and mid-/long-term development plans that suit for the characteristics of Korean railroad through investigating the environmental policies of advanced countries.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.429-436
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• 2013

In this paper, For achieving the high gain and resonant characteristics in both of the power flow directions, a bidirectional resonant dc-dc converter with auxiliary switches is proposed. Auxiliary switches are connected in the primary and secondary side of the bidirectional resonant dc-dc converter, respectively. A 800W prototype bidirectional resonant dc-dc converter for interfacing the 400V DC buses in the energy storage system is built and tested to verify the validity and applicability of this proposed converter.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.41-42
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• 2012

For achieving the high gain and resonant characteristics in both of the power flow directions, a bidirectional resonant dc-dc converter with auxiliary switches is proposed. Auxiliary switches are connected in the primary and secondary side of the bidirectional resonant dc-dc converter, respectively. A 1kW prototype bidirectional resonant dc-dc converter for interfacing the 400V DC buses in the energy storage system is built and tested to verify the validity and applicability of this proposed converter.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.253-261
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• 2018

Korea Astronomy and Space Science Institute (KASI) has been developing the space optical and laser tracking (SOLT) system for space geodesy, space situational awareness, and Korean space missions. The SOLT system comprises satellite laser ranging (SLR), adaptive optics (AO), and debris laser tracking (DLT) systems, which share numerous subsystems, such as an optical telescope and tracking mount. It is designed to be capable of laser ranging up to geosynchronous Earth orbit satellites with a laser retro-reflector array, space objects imaging brighter than magnitude 10, and laser tracking low Earth orbit space debris of uncooperative targets. For the realization of multiple functions in a novel configuration, the SOLT system employs a switching mirror that is installed inside the telescope pedestal and feeds the beam path to each system. The SLR and AO systems have already been established at the Geochang station, whereas the DLT system is currently under development and the AO system is being prepared for testing. In this study, the design and development of the SOLT system are addressed and the SLR data quality is evaluated compared to the International Laser Ranging Service (ILRS) tracking stations in terms of single-shot ranging precision. The analysis results indicate that the SLR system has a good ranging performance, to a few millimeters precision. Therefore, it is expected that the SLR system will not only play an important role as a member of the ILRS tracking network, but also contribute to future Korean space missions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1383-1388
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• 2011

Due to many recent activities on enforcement of the intensified environmental regulation such as the policies of curbing the greenhouse gas and the Restriction of Hazardous Substances (RoHS), the usage of Light emitting diode (LED) has been rapidly increased and energy efficient management of LED light system is regarded as an important technology to enhance the energy efficiency. In this paper, we propose an energy-efficient control scheme of LED light, being composed of multiple light sources. The proposed scheme controls the intensity of LED light source to minimize the total intensity while providing the quality of lighting service. The intensity of light is assumed to be proportional to power consumption, thus the objective is to minimize the total power consumption. A linear programming problem is formulated to find the optimal intensity of each light source and procedure to apply the proposed scheme in the real system is suggested. The performance evaluation results elucidate that the proposed scheme achieves over 20% improvement in power consumption of light intensity in comparison with the conventional dimming control scheme.