• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.329-335
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• 2018

Satellite images, which are widely used in various applications, are very useful for monitoring the surface of the earth. Since satellite data is obtained from a remote sensor, it contains a lot of noise and errors depending on observation weather conditions during data acquisition and sensor malfunction status. Since the accuracy of the data affects the accuracy and reliability of the data analysis results, noise removal and data restoration for high quality data is important. In this study, we propose a reconstruction system that models the time dependent dynamic characteristics of satellite data using a multi-period harmonic model and performs adaptive data restoration considering the spatial correlation of data. The proposed method is a real-time restoration method and thus can be employed as a preprocessing algorithm for real-time reconstruction of satellite data. The proposed method was evaluated with both simulated data and MODIS NDVI data for six years from 2011 to 2016. Experimental results show that the proposed method has the potentiality for reconstructing high quality satellite data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.1082-1090
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• 2009

Peak expiratory flow rate(PEF) is a very important diagnostic parameter obtained from the forced vital capacity(FVC) test. The expiratory flow rate increases during the short initial time period and may cause measurement error in PEF particularly due to non-ideal dynamic characteristic of the transducer. The present study evaluated the initial rise slope($S_r$) on the flow rate signal to compensate the transducer output data. The 26 standard signals recommended by the American Thoracic Society(ATS) were generated and flown through the velocity-type respiratory air flow transducer with simultaneously acquiring the transducer output signal. Most PEF and the corresponding output($N_{PEF}$) were well fitted into a quadratic equation with a high enough correlation coefficient of 0.9997. But only two(ATS#2 and 26) signals resulted significant deviation of $N_{PEF}$ with relative errors>10%. The relationship between the relative error in $N_{PEF}$ and $S_r$ was found to be linear, based on which $N_{PEF}$ data were compensated. As a result, the 99% confidence interval of PEF error was turned out to be approximately 2.5%, which was less than a quarter of the upper limit of 10% recommended by ATS. Therefore, the present compensation technique was proved to be very accurate, complying the international standards of ATS, which would be useful to calibrate respiratory air flow transducers.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.404-404
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• 2012

저차원계 탄소 동소체는 특유의 구조에서 기인하는 우수한 물리적 성질로 인해 각광받고 있는 물질이다. 탄소원자가 육각형 격자 모양을 지닌 2차원계 물질인 그래핀(graphene)은 뛰어난 전기적, 물리적, 광학적 성질로 인해 전계효과 트랜지스터(field effect transistors), 투명전극(transparent electrodes), 에너지 저장체, 복합체, 화학/바이오 센서 등 다양한 분야에서 활용을 위한 연구가 진행되고 있다. 또한 그래핀이 튜브형태로 말려있는 1차원계 물질인 탄소나노튜브(carbon nanotube)의 전기적, 열적, 기계적 성질은 이를 전계방출 디스플레이(field emission display), 전도성 플라스틱, 가스 저장체, 슈퍼 커패시터 등에 적용가능하게 한다. 최근 2차원계 물질인 그래핀과 1차원계 물질인 탄소나노튜브의 장점을 극대화하기 위한 복합 나노 구조에 대한 다양한 연구가 진행되고 있는 추세이다[1-5]. 본 연구에서 그래핀-탄소나노튜브 혼성 구조의 제작은 다음과 같이 진행되었다. 우선 열 화학기상증착법(thermal chemical vapor deposition)을 이용하여 그래핀을 합성하였다. 합성된 그래핀은 메타크릴산메탈 수지(polymetylmethacrylate; PMMA)를 이용한 전사(transfer)방법을 이용하여 원하는 기판에 위치시키고, 직류 마그네트론 스퍼터링(DC magnetron sputtering)을 이용하여 탄소나노튜브의 합성을 위한 촉매층을 증착하였다. 이후 열 화학기상증착법을 이용하여 그래핀 위에 탄소나노튜브를 합성함으로써 그래핀-탄소나노튜브 혼성 구조를 제작하였다. 합성된 그래핀-탄소나노튜브의 구조적 특징은 주사 전자 현미경(scanning electron microscopy)을 통해 확인하였고, 촉매의 표면 형상 및 화학적 상태는 원자힘 현미경(atomic force microscopy)과 X선 광전자 분광법(X-ray photoelectron spectroscopy)을 통해 확인하였다. 또한 제작된 그래핀-탄소나노튜브의 전기적 특성 측정을 통해 나노전자소자로의 응용가능성을 조사하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.113-119
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• 2016

In this study, the method to predict the lateral response by using strain data is presented on the steel moment frame. For this, the reliability of the proposed method by applying the example of five-story frame structure were verified. Using the strain value of columns, it predicted the lateral response of structure. It is assumed that all of four strain sensors for one column set up and the strain responses of both end of the column are utilized. The lateral response of member is calculated by using the slope deflection method. Also, using the acceleration response of the one layer, the stiffness of the rotation spring located in the supporting point is predicted. As a result, it was effective to understand the lateral displacement and acceleration responses and to predict local damage and location.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.191-193
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• 2003

Temporal and spatial variability of phytoplankton pigment concentrations around the Korea Peninsula was described, using the monthly mean composite images of the SeaWiFS (Sea-Viewing Wide Field-of-View Sensor). The high pigment concentrations appear in the spring and fall in the East Sea The spring bloom in the southern regions (in April) occurs one month in advance in comparison with tint in the northern regions (in May). In summer season, the pigment concentrations are low all over the region in the East Sea And the high pigment concentrations exist yearly around warm stream along the coast of the East Sea, and in the coast of the West Sea and South Sea In particular, the high pigment concentrations linking near the mouth q the Yangze River to coast of South Sea in Korea appear during August to December.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.96-102
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• 2013

In recent years, a variety of ITS services are available such as driving information, road conditions, V2X messages as well as navigation and traffic jams notification. The development of ITS services is accelerating by V2X communication technologies for high-speed vehicles. In this paper, WAVE communication devices based on the IEEE802.11p standard is introduced as a solution of V2X communication technologies. The H/W and S/W structures of the WAVE communication device and the characteristics of RF/antenna are described. The performance is evaluated in the test road by measuring throughput, PER and latency. The implemented WAVE communication device has 6~7 Mbps throughput with 10% PER at 1km coverage. The packet latency is less than 3ms for the whole test road. It is shown that the implemented WAVE technology is satisfactory to provide ITS services and Internet video-streaming services.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.6
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• pp.637-644
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• 2010

The purpose of this study is to analyze characteristics of water quality factor scientifically and develop the multiple regression model predicting dissolved oxygen to save periodic replacement costs for dissolved oxygen sensor. Correlation analysis using the environmental data obtained from 2 different land-based fish farms of the Geogeum-do, Geheung-gun coastal area during the periods from November 2008 to January 2009 shows that water temperature was negatively correlated with dissolved oxygen and pH butpH was positively correlated with salinity and dissolved oxygen. The information of Keumho fish farm in 2009 is presented by the tables which are monthly statistics of water quality factors and seasonable difference by the Duncan's post-test. Also we developed multiple regression model predicting dissolved oxygen, the usefulness of which was verified by the comparison graph between estimates and actual observations. The developed regression model shows that seawater temperature and salinity give negative affect to dissolved oxygen while pH gives positive affect to it. Lastly the seawater temperature has much higher explanatory power than pH factor.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.127-134
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• 2011

In this paper we propose an improved PV generation systems. Improved systems for temperature and humidity controlled heating and air conditioning offers a pleasant environment within the building, set up chopper and consists of a PWM voltage type inverter. The proposed system is stable modulation for a one-chip microprocessor using the synchronous signal and control signals was treated. The proposed system is a PWM voltage type inverter and phase of the synchronous to the grid voltage to detect the system voltage and inverter output to drive the statue, so surplus power to connection was able to, certain buildings such as buildings or hospitals, temperature and humidity sensor is applied to the good dynamic characteristic could be obtained. In addition, the system was applied to the high power factor and low-frequency harmonics by maintaining the output load and grid to power to be supplied to a stable control could get a good result.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.852-857
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• 2010

As the wind has become one of the fastest growing renewable energy sources, the key issue of wind energy conversion systems is on how to efficiently operate the wind turbines in a wide range of wind speeds. In general, the wind speed is the main factor that impact on the dynamics of wind turbine system. Wind turbine algorithms are thus required to improve the performance of wind speed measurements. However, the accurate measurement of the effective wind speed using wind gauge and similar sensors is difficult such that control systems are needed for wind speed estimation using various techniques. Therefore, this research suggests the Maximum Power Point Tracking (MPPT) method for tracking the wind speed based on neural networks. Design experiments were carried out in laboratory environment to validate the application of the proposed method.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.5
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• pp.710-715
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• 2010

As wind has become one of the fastest growing renewable energy sources, the key issue of wind energy conversion systems is how to efficiently operate the wind turbines in a wide range of wind speeds. The wind speed has a huge impact on the dynamic response of wind turbine. For this purpose, many control algorithms are in need for a method to measure wind speed to increase performance. Unfortunately, no accurate measurement of the effective wind speed is online available from direct measurements, which means that it must be estimated in order to make such control methods applicable in practice. In this paper, a new method based on Kalman filter and artificial neural network is presented for the estimation of the effective wind speed. To verify the performance of the proposed scheme, some simulation studies are carried out.