• Journal of Navigation and Port Research
• /
• v.39 no.3
• /
• pp.179-184
• /
• 2015

The purpose of this study is to provide appropriate methodology to ensure the safety and integrity of the production riser in offshore structure. In order to select integrity estimation methodology for production riser, level I and II Non-destructive Damage Evaluation (NDE) methods that were applied to existing structures are classified and reviewed. Numerical analysis is performed to verify the applicability and capability on damage detection of reviewed methods. As a result, the damage detection methodology using modal strain energy is more sensitive in detection of the damage than other methods. In practice, the number of sensors is limited due to the environmental and financial conditions. The impact on damage detection performance by reducing the number of sensors is systematically investigated through a series of numerical analyses and the results are discussed. The optimal number of sensor for the integrity estimation of production riser is recommended.

• Journal of Korea Multimedia Society
• /
• v.22 no.11
• /
• pp.1324-1337
• /
• 2019

This study set out to investigate an energy harvesting device to ensure stable energy supply to batteries and data collection devices and a monitoring system for acer pictum sap to check collected data. Acer pictum sap farmers have written down weather information and yield of acer pictum sap manually for data storage. Since the job is done manually, there are many missing values in their data. In addition, it is not easy to manage batteries due to the characteristics of the areas where acer pictum sap is collected. The present study thus decided to build an energy harvesting device based on new renewable energy to ensure stable energy supply by taking into consideration power load, daily power consumption, and number of days with no sunshine for various devices. For a monitoring system, the investigator proposed a JSP-based web page to monitor temperature, humidity, volume of collected water, and battery state in real time. The proposed energy harvesting device was applied to reduce missing values in data. It promoted stable energy supply to the batteries and data collection devices, reducing the percentage of missing values in data from 30.55% to 0%.

• Journal of Korean Society of Transportation
• /
• v.26 no.5
• /
• pp.51-62
• /
• 2008

An innovative feature of this study is to propose a methodology for evaluating safety performance in real time based on vehicle trajectory data extracted from video images. The essence of evaluating safety performance is to capture unsafe car-following and lane-changing events generated by individual vehicles traveling within video surveillance area. The proposed methodology derived three indices including real-time safety index(RSI) based on the concept of safe stopping distance, time-to-collision(TTC), and the collision energy based on the conservation of momentum. It is believed that outcomes would be greatly utilized in developing a new generation of video images processing(VIP) based traffic detection systems capable of producing safety performance measurements. Relevant technical challenges for such detection systems are also discussed.

• Proceedings of the IEEK Conference
• /
• 2009.05a
• /
• pp.279-280
• /
• 2009

최근 경세성장과 함께 생활수준의 향상으로 인하여 에너지 수요는 매년 증가하고 있으며 그 중에서 하나인 전력수요도 역시 급격히 늘어나고 있는 추세이다. 이와 더불어 투자자원 및 입지확보의 어려움, 환경제약의 문제로 전력 공급의 어려움은 날로 증가되고 있다. 따라서 수요증가를 전력공급 능력의 증진뿐만 아니라 수요관리 측면에서도 필요성이 대두되고 있다. 전력선 통신은 전력선을 매체로 하기 때문에 신규선로의 포설 없이 가전기기 및 정보화 서비스 모뎀들의 네트워크화에 용이할 뿐만 아니라 커버리지 확장에도 뛰어나서 디지털 가전, 원격검침, 전력설비 감시제어, 국가 재난 감시 시스템 등의 기본 통신 방식으로 가장 유력한 기술로써 디지털 가전을 포함한 유비쿼터스 전기설비 네트워크 구성에서 필수적 기술로 채택되고 있기 때문에 지능형 홈 네트워크, 전력IT 부가서비스, 설비감시 네트워크, 유비쿼터스 네트워크 관련 기술에 대한 파급 효과가 매우 크며, 디지털 가전의 기본 통신 방식으로 가장 유력한 기술로써 디지털 가전 구성에서 필수적 기술로 채택되고 있기 때문에 지능형 홈 네트워크 관련 기술에 대한 파급 효과가 매우 크다. 본 연구에서는 전력선통신모뎀을 이용하여 가전기기의 전력 소비를 감지할 수 있는 센서를 내장한 전력선 통신기반의 전력 감시 모듈을 개발하여 실시간 원격 모니터링을 통해 소비전력 패턴을 작성한다. 그리고 전력감시 모듈에 연결된 가전기기의 소비전력 패턴 분석을 통해 전력소비 이상 유무를 감지할 수 있는 알고리즘을 개발, 탑재하여 이상유무를 판단하고 전력소비가 급증할 시 자동으로 전력을 차단하여 화재나 누전의 위험을 방지한다. 이에 본 연구는 전력선통신을 이용하여 전력소비감시 및 이상전력차단에 관한 연구에 관한 것이다.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.1
• /
• pp.193-198
• /
• 2016

For environmental monitoring and risk identification of industrial plants, several monitoring systems using Wireless Sensor Networks (WSNs) have been developed. In this paper, we propose a dynamic duty cycle adjustment mechanism for reduced latency in industrial plants. The proposed method adjusts the duty cycle among predefined risk groups depending on the urgency of sensed data values. To demonstrate its efficacy, we analyze the expected transmission latency model and then discuss the characteristics in detail. We show that the proposed dynamic duty cycle mechanism is a more effective than a periodic mechanism by analyzing the expected latency of them in industrial plants where there are various types of sensory data with different levels of reliability.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.1
• /
• pp.35-42
• /
• 2013

This paper shows the positivistic approach for analyzing the effect of ICT on the reduction of greenhouse gas (GHG) emission. The real-time navigation was selected for the ICT based service in this research, and the CO2 reduction ratios of the optimized routes in the navigation were compared with the reduction ratios of the shortest routes in existing navigations. The results of experiments showed the driving based on the optimized routes has more reduction effects than the driving on the basis of the shortest routes. Also, new evaluation method for GHG emission was suggested by the quantification and monitoring approaches on the basis of the Clean Development Mechanism (CDM) in this paper. The results of this paper can be used as a preliminary research for the effect of ICT on the reduction of GHG emission. The evaluation method which suggested in this paper will be suggested to CDM as the new standard for the reduction of GHG emission in the transportation field as well.

• International Journal of Highway Engineering
• /
• v.14 no.2
• /
• pp.73-81
• /
• 2012

The bicycle is an environment-friendly transport mode leading to a more sustainable transportation system. To innovatively increase the use of bicycle as a significant transport mode, bicycling-friendly roadway environment should be provided. From this perspective, the scientific and effective assessment of roadway environment in term of the bicyclist perception for safety and comfortability is of keen interest. This study develops a methodology for evaluation cycling environment using probe bicycles. A global positioning system(GPS) based speedometer was used to collect bicycle speed data. Cycling comfortability index(CCI) was derived for the purpose of evaluating cycling environment. The proposed CCI can be effectively used as an assessment tool in the field of bicycle transportation.

• Composites Research
• /
• v.24 no.6
• /
• pp.49-55
• /
• 2011

The use of advanced composite materials in main structures of military and civil aircraft has been increased rapidly because of their considerable metals in high specific strength and stiffness. However, the mechanical properties of composite materials may severely degrade in the presence of damage. Especially, the high-velocity impact such as a hailstorm, and a small piece of tire or stone during high taxing, can cause considerable damage to the structures and sub-system in spite of a very small mass. However, it is not easy to detect the damage in composite plates using a single sensor or any conventional methods. In this paper, the PVDF sensors and AE sensors were used for monitoring high-velocity impact damage initiation and propagation in composite laminates. The WT(wavelet transform) is used to decompose the sensor signals. In the PVDF sensor and AE sensor signal analysis, amounts of high-frequency signals are increased when the impact energy is increased. PVDF sensor and AE sensor signal appeared similar results. This study shows how various sensing techniques can be used to characterize high-velocity impact damage of advanced composite laminates.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.8
• /
• pp.1836-1842
• /
• 2010

Sensor network, which is technology to realize the ubiquitous environment, recently, could apply to the field of Mechanic & electronic Security System, Energy management system, Environment monitoring system, Home automation and health care application. However, feature of wireless networking of sensor network is vulnerable to eavesdropping and falsification about message. Presently, PKC(public key cryptography) technique using ECC(elliptic curve cryptography) is used to build up the secure networking over sensor network. ECC is more suitable to sensor having restricted performance than RSA, because it offers equal strength using small size of key. But, for high computation cost, ECC needs to enhance the performance to implement over sensor. In this paper, we propose the optimizing technique for multiplication, core operation in ECC, to accelerate the speed of ECC.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.100-100
• /
• 2019

최근 대기 중 미세먼지의 농도가 높은 일수가 급증하면서, 미세먼지를 저감하고자 하는 연구가 활발히 이루어지고 있다. 미세먼지는 주로 자동차 혹은 공장 등 인간 활동에 의한 오염물질 배출에 의해 발생하는 것으로 알려져 있으며, 태양복사에너지, 토양수분, 강우, 풍속 등의 수문기상학적 인자에 의해 발생, 이동, 소멸의 과정을 거친다. 현재 우리나라에서는 미세먼지 농도를 관측하기 위해 지점 기반의 관측소를 운영하고 있으며, 관측소가 위치하지 않은 지역의 미세먼지 농도는 선형 보간법 등을 활용한 내삽 기법을 통해 제공하고 있다. 그러나 미세먼지 농도는 다양한 수문기상인자들의 영향에 의한 차이가 크게 나타나기 때문에 지점 기반의 자료로는 해당 지역의 미세먼지 농도를 추정하는 데 어려움이 많다. 본 연구에서는 미세먼지의 공간적인 분포를 추정하고자 MODerate resolution Imaging Spectroradiometer (MODIS) 에어로졸 자료와 Global Land Data Assimilation System (GLDAS) 수문기상인자를 활용하여 미세먼지 농도에 영향을 주는 것으로 판단되는 다양한 수문기상인자들과의 상관성을 분석하였다. 미세먼지와 각 인자간의 상관성을 분석하여 높은 상관성을 갖는 수문기상인자들을 도출하고 최적의 선형회귀분석 모델을 구축하기 위해 베이지안 모델 평균(Bayesian Model Averaging, BMA)을 사용하였으며, 지점 데이터와의 비교를 통해 활용성을 검증하였다. 전체적으로 수문기상인자를 사용한 선형회귀분석 결과에서는 미세먼지농도 변화의 경향을 반영하고 있는 것을 확인할 수 있었으나, 계절별, 지역별 등 대기 특성을 고려하지 않아 각 기간의 급격한 농도 변화를 감지하기에 어려움이 있었다. 이러한 연구를 바탕으로 수문기상인자와 미세먼지 농도의 패턴이 더욱 정확히 분석된다면, 미세먼지 농도 모니터링과 정확한 예보 시스템의 구축에 효과적으로 활용 될 것으로 기대된다.