• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.900-905
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• 2016

The field of power system harmonics has been receiving a great deal of attention recently. This is primarily due to the fact that non-linear (or harmonic-producing) loads comprise an ever-increasing portion of what is handled at a typical industrial plant. The incidence rate of harmonic-related problems is low, but awareness of harmonic issues can still help increase offshore power plant system reliability. On the rare occasion that harmonics become a problem, this is either due to the magnitude of harmonics produced or power system resonance. This harmonic study used an electrical configuration for the offloading scenario of a Floating LNG (FLNG) unit, considering power load. This electrical network configuration is visible in the electrical network load flow study part of the project. This study has been carried out to evaluate the performance of an electric power system, focusing on the harmonic efficiency of an electrically driven motor system to ensure offshore plant safety. In addition, the design part of this study analyzed the electric power system of an FLNG unit to improve the safety of operation and maintenance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.581-584
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• 2009

Recently, the cameras which used for observation are installed in children protection area and local crime prevention area in order to protect life and property and by its work being recognized and are installed more. Normal cameras have cost problem to observe multiple area and detail, because they can observe only one place. PTZ camera can observe multiple area by moving focus by schedule or remote control, but it can't automatically move the focus of it to the place where event occurred, because it can't recognize the place. In this study, we can monitor multiple area effectively, by installing a wireless sensor node equipped with temperature, lighting, gas and human detection sensor to each area, to monitor many place low-price and actively and to move the focus of PTZ camera to preset position, and send recorded video to the user, when the various sensor data received from wireless sensors in observation area are to be determined abnormal by analyzing. In addition, at night we can record a scene using infrared, but to reduce power consumption of lighting system which are installed to improve resolution, it supplies power to the lighting system when event occurred. So we were able to implement low power green monitoring system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.74-82
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• 2019

The revolution of industry 4.0 is enabling us to build an intelligent connection society called smart cities. The use of renewable energy in particular solar energy is extremely important for modern society due to the growing power demand in smart cities, but its difficult to monitor and manage in each buildings since need to be deploy low energy sensors and information need to be transfer via wireless sensor network (WSN). The Internet of Things (IoT) / low-power wide-area (LPWA) is an emerging WSN technology, to collect and monitor data about environmental and physical electrical / electronics devices conditions in real time. However, providing power to IoT sensor end devices and other public electrical loads such as street lights, etc is an important challenging role because the sensor are usually battery powered and have a limited life time. In this paper, we proposes an efficient solar energy-based power management scheme for smart city based on IoT technology using LoRa wide-area network (LoRaWAN). This approach facilitates to maintain and prevent errors of solar panel based energy systems. The proposed solution maximizing output the power generated from solar panels system to distribute the power to the load and the grid. In this paper, we proved the efficiency of the proposed system with Simulink based system modeling and real-time emulation.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.420-420
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• 2011

도시지역의 내수침수피해는 거의 매년 발생하고 있으며, 반지하와 같은 거주공간이 매우 취약한 상태이다. 특히 최근에는 지하철, 지하상가 등이 대규모 개발되고 복합네트워크화 되어 지하공간의 침수대책과 대피방안 마련이 시급한 상황이다. 일본의 경우 2000년 토카이 호우피해 후 통합유출해석 모형을 개발하였으며, 1999년 및 2003년 후쿠오카 침수피해 발생 후 특정도시하천침수피해대책법을 제정, 1999 후쿠오카, 2004년 하마마츠, 2008년 카누마 피해 후 일본 방재연구소에서는 실시간 1차원 지표범람모형과 모니터링을 통한 실시간 내수침수지도를 개발하였다. 특히 지하공간에 대해서는 "지하공간에 유입하는 범람수가 계단상 보행자게에 주는 위험성에 관한 연구" 등 실험을 바탕으로 각종 지하공간 침수대책 매뉴얼 및 지하시설의 침수시 피난확보계획 지침, 지하공간 침수대책 가이드라인 등 인명피해를 줄이고자하는 노력이 계속되어 오고 있다. 우리나라는 2006년 경기도 고양시 3호선 정발산역이 침수되었으며, 2010년 서울시 지하철 2호선 사당역 및 4호선이 침수되는 등의 지하철 침수피해와 2010년 서울시 광화문 지하상가, 인천시 부평구 우림라이온스 벨리, 우남플라자, 계양구 농협하나로마트, 서원아파트 등의 지하상가와 지하다층의 침수피해가 발생하였다. 특히 2006년 3호선 정발산역 침수는 17시간이나 지하철이 불통되었고 이로 인하여 심각한 교통 체증이 유발 되었다. 본 연구에서는 2010년 집중호우로 인한 서울, 인천지역의 지하공간 침수피해를 중심으로 최근 10년간 지하공간 침수피해사례로부터 대표적인 침수피해 원인 및 특성을 정리하였으며, 그 결과 지하공간 침수의 주요원인은 지상공간의 침수류가 지하공간으로 유입하고, 지하공간의 배수설비 용량부족, 지하공간으로의 유입을 방지하기위한 방지턱, 차수판, 침수시 비상전원 공급, 침수시 지하공간 대피 매뉴얼의 부재 등 다양한 원인이 있는 것으로 나타났다. 특히, 소방방재청에서 고시한 '지하공간 침수방지를 위한 수방기준'에 지하공간 침수 방지를 위한 각종 시설의 설치 및 대피 경로지정 등에 대한 기준이 마련되어 있으나, 지하공간 중 유동인구가 가장 많은 지하철역에서 조차 침수에 대한 행동매뉴얼이나 대피에 대한 가이드라인이 마련되지 않은 것으로 나타났다. 따라서, 지하공간 침수를 방지하기 위하여 센서를 이용한 자동 차수판과 경보기 설치, 지하공간의 사람들이 안전한 대피로를 찾을 수 있도록 지상공간 및 지하공간 출입구를 모니터링 할 수 있는 CCTV의 설치, Dry Area를 두어 비상대피 할 수 있는 공간의 마련 등 시설적인 부분에 대하여 '지하공간 침수방지를 위한 수방기준'을 더욱 강화할 필요가 있으며, 지상공간의 침수 상황을 고려한 지하공간의 대피매뉴얼 또는 가이드라인 등의 수립이 필요하다. 또한 이와 더불어 재산 및 인명피해를 더욱 효율적으로 줄일 수 있도록 실시간 예 경보를 위한 침수해석 모형의 개발이 시급하다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.669-672
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• 2015

Recent Internet of Things (IoT, Internet of Things) that can be applied to various fields as the development of technology has been developed a lot of service and has been developed with the service also for crop management. To manage the essential elements of soil moisture in the crop growth but existing a direct person measuring the fluid point to carry the measuring instrument, if you take advantage of the WPAN (Wireless Personal Area Network) in this paper to manage sensor data, a fixed 3 points (30, 60, 90 cm) and can be managed can be scientifically analyzed the state of growth of the crop. Open field environment is utilized as it is less disturbance of the interference and the frequency of the radio frequency signal of the structure provides a relatively comfortable environment. Therefore, WPAN building and data transmission scheme of the minimum cost is to be developed. In addition, the operation to enter low power mode, the algorithm is necessary because a lot of restrictions on the power supply applied to the sensor nodes and the gateway is constructed in the open field. In the experiment, verifying the effectiveness by using a network configuration of each of the sensor nodes and the gateway, and provides a method for time synchronization of the operation and a low power mode. The study protocol for the RF communication with the LoRa and to enhance communication efficiency is needed in the future.