• JSTS:Journal of Semiconductor Technology and Science
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• 제14권6호
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• pp.810-817
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• 2014

An on-chip current sensor with fast response time for the peak-current-mode buck regulator is proposed. The initial operating points of the peak current sensor are determined in advance by the valley current level, which is sensed by a valley current sensor. As a result, the proposed current sensor achieves a fast response time of less than 20 ns, and a sensing accuracy of over 90%. Applying the proposed current sensor, the peak-current-mode buck regulator for the mobile application is realized with an operating frequency of 2 MHz, an output voltage of 0.8 V, a maximum load current of 500 mA, and a peak efficiency of over 83%.

• 한국정보전자통신기술학회논문지
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• 제9권6호
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• pp.624-629
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• 2016

Recently various types of disaster monitoring system using smart-phones are under active studying. In this paper, we propose a system that automatically performs the disaster and fire detection. Additionally we implement the Arduino-based smart image sensor system in the web platform. When a fire is detected, an SMS is sent to the Fire and Disaster Management Agency. In order to improve fire detection probability, we proposed a smart Arduino fire detection sensor simulation which searches the smart sensor inference algorithm using fuzzy rules.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.497-498
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• 2007

The most of important thing when we design a Wireless Sensor Network is resources. You have to consider energy efficient operation When you design Wireless Sensor Network. Because Sensor devices have a limited resources. In this paper, we proposed energy efficiency localization technique in Wireless Sensor Network. We used Cell ID technique for location search. This method can reduce power consumption and the network life time will be extension.

• 한국정보전자통신기술학회논문지
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• 제11권1호
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• pp.89-94
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• 2018

본 논문에서는 IoT (Internet of Things) 서비스 구현을 위한 스마트센서의 설계 방안을 연구하였다. 지속적인 데이터 수집을 위한 센서의 전원 공급부는 에너지 하베스팅 (Energy Harvesting) 기술을 적용하였으며, 주변 환경으로부터 영향을 줄일 수 있는 압전소자 (piezoelectric transducer)를 선택하여 전원 공급부를 설계하였다. 데이터 전송을 위한 무선통신 인터페이스는 BLE (Bluetooth Low Energy) 기술을 적용하여 설계하였다. BLE는 저전력 단거리 무선 통신에 적합하며, 주요 응용분야인 BLE 비콘 (beacon)은 O2O (Online to Offline) 서비스, 실내 측위 기반의 내비게이터, 도난/미아 방지 서비스에서 모바일 게임 등으로 활용 범위가 확대되고 있다. BLE 무선통신의 짧은 전송 거리를 보완하기 위해 무선 커버리지를 확대할 수 있는 방안을 연구하였으며, 네트워크 구축이 용이하고 무선 커버리지 확대할 수 있는 CATV 망을 활용한 BLE 센서 네트워크 구축 방안을 제안하였다.

• International Journal of Contents
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• 제11권2호
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• pp.31-36
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• 2015

Recent years have seen a significant increase in demand for multimedia data over wireless sensor networks for monitoring applications that utilize sensor nodes to collect multimedia data, including sound and video. However, the multimedia streams generate a very large amount of data. When data transmission schemes for traditional wireless sensor networks are applied in wireless multimedia sensor networks, the network lifetime significantly decreases due to the excessive energy consumption of specific nodes. In this paper, we propose a data compression scheme that implements the Chinese remainder theorem to a wireless multimedia sensor network. The proposed scheme uses the Chinese Remainder Theorem (CRT) to compress and split multimedia data, and it then transmits the bit-pattern packets of the remainder to the base station. As a result, the amount of multimedia data that is transmitted is reduced. The superiority of our proposed scheme is demonstrated by comparing its performance to that of an existing scheme. The results of our experiment indicate that our proposed scheme significantly increased the compression ratio and reduced the compression operation in comparison to those of existing compression schemes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.351-352
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• 2007

The sensor networking technique as the radio network which does not have the base infrastructure network. The sensor nodes oneself automatic compose the network and simultaneously accomplish two roles of the router and data source. The sensor network is kind of Ad-hoc network is a possibility of seeing from point. sensor networking technique is restricted that limit of the memory and the battery back with the resources of the node. The sensor nodes overcomes the restriction of the resources it is in the process of researching the multi-hop routing technique which the sensor network divided cluster routing techniques which are researched. this paper proposed using beamforming antenna which has the directivity of the electric wave. the beamforming antenna from the Ad-hoc network using technique. the proposal is that raises the efficient of data trans mission from the sensor network and extends the lift time of the sensor network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.241-269
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• 2012

Wireless networks composed of multimedia-enabled resource-constrained sensor nodes have enriched a large set of monitoring sensing applications. In such communication scenario, however, new challenges in data transmission and energy-efficiency have arisen due to the stringent requirements of those sensor networks. Generally, congested nodes may deplete the energy of the active congested paths toward the sink and incur in undesired communication delay and packet dropping, while bit errors during transmission may negatively impact the end-to-end quality of the received data. Many approaches have been proposed to face congestion and provide reliable communications in wireless sensor networks, usually employing some transport protocol that address one or both of these issues. Nevertheless, due to the unique characteristics of multimedia-based wireless sensor networks, notably minimum bandwidth demand, bounded delay and reduced energy consumption requirement, communication protocols from traditional scalar wireless sensor networks are not suitable for multimedia sensor networks. In the last decade, such requirements have fostered research in adapting existing protocols or proposing new protocols from scratch. We survey the state of the art of transport protocols for wireless multimedia sensor networks, addressing the recent developments and proposed strategies for congestion control and loss recovery. Future research directions are also discussed, outlining the remaining challenges and promising investigation areas.

• 대한임베디드공학회논문지
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• 제2권3호
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• pp.138-144
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• 2007

Wireless Sensor Network(WSN) consists of a lot of light-weight sensor nodes with the capability of wireless communication. Studies have been done to improve stability and fault-tolerancy of WSN because the sensor nodes are basically vulnerable to the harsh environment. Specially, the time synchronization among sensor nodes becomes a challenging issue in WSN. All the local times should always keep the same with each other in the sensor field to perform data aggregation and energy-aware communication in WSN. In this paper, a new time synchronization technique is proposed to operate efficiently irrespective of the number of sensor nodes and the number of hops needed to cover all sensor nodes for synchronization. Simulation results show that the proposed technique has the lowest amount of packet traffic among the several time synchronization techniques.

• 전기학회논문지
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• 제64권2호
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• pp.284-288
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• 2015

The color temperature flexibility-typed Lighting Emitting Diode(LED) lighting control system proposed in this thesis employs Pulse Width Modulation(PWM) technique to control the brightness of LED lighting. The LED lighting used as a light source has 20W downlight composed of two types of LED chips: one is Warm White and the other is Cool white. One multi-sensor module consisting an infrared sensor, an illumination sensor, and a temperature sensor was made, to which Bluetooth wireless communication technique was applied to enable a smartphone application to control lighting brightness and identify the information collected from the sensor. CS-1000, a spectroradiometer, was used to measure LED dimming control and the changing values of a color temperature in eight steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5600K of Cool White LED.

• 전자공학회논문지
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• 제49권11호
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• pp.97-102
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• 2012

최근 지중 시설물은 공간적 제약에 의하여 관리가 쉽지 않기 때문에 무선 통신 센서 네트워크를 도입하려는 시도가 이루어지고 있다. 수백 MHz ~ 수 GHz 대역의 전자기파를 이용한 통신을 사용할 경우 불균질한 물질에서의 통신 성능의 급격한 변화로 인하여 원활한 통신이 어려운 상황이다. 본 연구에서는 이러한 단점을 극복하기 위하여 자기장을 이용한 통신 시스템을 구축하였다. 3m 토압 및 물의 침투를 막을 수 있는 시설물을 제작하여 무선 통신 센서 네트워크 시스템를 설치하였다. 3m 깊이로 땅을 파서 시설물을 매립한 뒤 통신 성능 테스트를 진행하였다. 그 결과 흙, 돌, 물 등이 불균일하게 분포되어 있는 지중에서도 무선 통신이 원활하게 이루어짐을 확인하였다. 따라서 자기장을 이용한 통신 시스템은 지중 시설물 및 연약 지반 관리, 환경 오염 관리 등에서 활용될 수 있을 것으로 기대된다.