• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.6 s.312
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• pp.68-75
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• 2006

During cancer therapy by using high energy radiation, it is possible to improve the radiation therapy efficiency by performing a precise radiation therapy after verification of generated setup errors. In this paper, the video based electronic portal imaging device (EPID) which could display the portal image with near real time was developed to verify treatment position errors in radiation therapy instead of an analog typed portal film. This EPID system for applying QA tool of radiation therapy machine was consisted of a metal/fluorescent screen, $45^{\circ}$mirror, camera and image grabber. Radiation field verification has been performed to check quality assurance of the treatment machine itself by using this EPID system. The radiation field error was easily observed by edge detection of irradiated field size on EPID image when $0.6^{\circ}$ shift of collimator angle was generated. So, this implemented EPID system could be used as a radiation QA tool.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.470-477
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• 2009

Modular reconfigurable robots with physical docking capability easily adapt to a new environment and many studies are necessary for the modular robots. In this paper, we propose a vision-based fuzzy autonomous docking controller for the modular docking robots. A modular docking robot platform which performs real-time image processing is designed and color-based object recognition method is implemented on the embedded system. The docking robot can navigate to a subgoal near a target robot while avoiding obstacles. Both a fuzzy obstacle avoidance controller and a fuzzy navigation controller for subgoal tracking are designed. We propose an autonomous docking controller using the fuzzy obstacle avoidance and navigation controllers, absolute distance information and direction informations of robots from PSD sensors and a compass sensor. We verify the proposed docking control method by docking experiments of the developed modular robots in the various environments with different distances and directions between robots.

• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.14-22
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• 2013

GPS radio occultation is a remote sensing technique probing atmospheric properties based on the fact that GPS signal is refracted and delayed by atmosphere. The FORMOSAT-3/COSMIC mission jointly developed by the USA and Taiwan is providing about 2500 occultation soundings a day on the near real-time basis. The Korean KOMPSAT-5/AOPOD system is preparing to launch for monitoring troposphere and ionosphere using a dual frequency GPS receiver and the antenna for occultation data acquisition. In this paper, we examine the methods for signal processing and the geometry analysis for GPS radio occultation, and look into the retrieval techniques for the temperature and humidity of troposphere and the electron density and scintillation of ionosphere. Using these atmospheric properties, we aim to derive the strategies for applying GPS radio occultation to space weather, for example, ionospheric TEC(total electron content) analysis for earthquake monitoring and the Open API(application programming interface) development for more effective data service.

• Journal of the korean society of oceanography
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• v.38 no.4
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• pp.173-184
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• 2003

Major differences between wind speeds from atmospheric pressure maps (Na wind) and near­surface wind speeds derived from satellite scatterometer (NSCAT) observations over the East (Japan) Sea have been examined. The root­mean­square errors of Na wind and NSCAT wind speeds collocated with Japanese Meteorological Agency (JMA) buoy winds are about $3.84\;ms^{-1}\;and\;1.53\;ms^{-1}$, respectively. Time series of NSCAT wind speeds showed a high coherency of 0.92 with the real buoy measurements and contained higher spectral energy at low frequencies (>3 days) than the Na wind. The magnitudes of monthly Na winds are lower than NSCAT winds by up to 45%, particularly in September 1996. The spatial structures between the two are mostly coherent on basin­wide large scales； however, significant differences and energy loss are found on a spatial scale of less than 100 km. This was evidenced by the temporal EOFs (Empirical Orthogonal Functions) of the two wind speed data sets and by their two­dimensional spectra. Since the Na wind was based on the atmospheric pressures on the weather map, it overlooked small­scale features of less than 100 km. The center of the cold­air outbreak through Vladivostok, expressed by the Na wind in January 1997, was shifted towards the North Korean coast when compared with that of the NSCAT wind, whereas NSCAT winds revealed its temporal evolution as well as spatial distribution.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.330-338
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• 2017

Purpose: The smartphone is actively being used in many research fields, primarily in medical and diagnostic applications. However, there are cases in which smartphone-based systems have been developed for agriculture, environment, and food applications. The purpose of this review is to summarize the research cases using smartphone cameras in agriculture, environment, and food. Methods: This review introduces seventeen research cases which used smartphone cameras in agriculture, food, water, and soil applications. These were classified as systems involving "smartphone-camera-alone" and "smartphone camera with optical accessories". Results: Detecting food-borne pathogens, analyzing the quality of foods, monitoring water quality and safety, gathering information regarding plant growth or damage, identifying weeds, and measuring soil loss after rain were presented for the smartphone-camera-alone system. Measuring food and water quality and safety, phenotyping seeds, and soil classifications were presented for the smartphone camera with optical accessories. Conclusions: Smartphone cameras were applied in various areas for several purposes. The use of smartphone cameras has advantages regarding high-resolution imaging, manual or auto exposure and focus control, ease of use, portability, image storage, and most importantly, programmability. The studies discussed were achieved by sensitivity improvements of CCDs (charge-coupled devices) and CMOS (complementary metal-oxide-semiconductor) on smartphone cameras and improved computing power of the smartphone, respectively. A smartphone camera-based system can be used with ease, low cost, in near-real-time, and on-site. This review article presents the applications and potential of the smartphone and the smartphone camera used for various purposes in agriculture, environment, and food.

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.389-399
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• 1997

The heavy strom of July 26-28, 1996, which occurred over the Northern Kyungi Province and Western Kangwon Province, is analyzed to investigate the hydrometeorological characteristics and frequency of occurrences of the storm. The study region is limited to the watershed area of Hantan River on which the partially destructed Yeonchon Dam is located. Hourly rainfall data at 21 rain gauging stations in and near the Hantan river basin are collected and the cumulative rainfall mass curves constructed and compared each other to judge the credibility and consistency of rainfall data at nearby stations. In order to analyze the spatially moving characteristics of rain storm the isochrones based on real time are constructed using the several fixed-percentage cumulative rainfalls at the stations. The basin average rainfalls of various durations are computed for Yeonchon dam and the return period of July/1996 storm are evaluated based on the rainfall frequency curves at Cheolwon and Yeonchon rain gauging stations. A comparison is also made between the July/1996 storm and PMP of the region, which demonstrated the severity of the heavy storm.

• Journal of the Korean Geophysical Society
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• v.8 no.2
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• pp.93-96
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• 2005

Focal mechanism of the real and imaginary faults in the western coast of Japan has been assumed by examining the previous studies on the seismicity, seismic gap, fault behaviors, seismic zoning, and faults. In the area of no seismic information, the focal mechanism has been assumed to have the maximum influence on the tsunami height in the eastern coast of Korea. The tsunami height in a particular point of the eastern coast of Korea can vary up to 7 orders with the variation of the strike of the fault in a particular source point of the western coast of Japan with constant magnitude. Tsunami scenario DB including the arrival times and tsunami heights has been constructing by using the assumed focal mechanism of the western coast of Japan. Tsunami warning system will be reinforced by using this tsunami scenario DB near future.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.5
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• pp.371-379
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• 2016

In the ship design process, ship motion and propulsion performance in sea waves became very important issues. Especially, prediction of ship propulsion performance during real operation is an important challenge to ship owners for economic operation in terms of fuel consumption and route-time evaluation. Therefore, it should be considered in the early design stages of the ship. It is thought that the averaged value and fluctuation of effective inflow velocity to the propeller have a great effect on the propulsion performance in waves. However, even for the nominal velocity distribution, very few results have been presented due to some technical difficulties in experiments. In this study, flow measurements near the propeller plane using a stereo PIV system were performed. Phase-averaged flow fields on the propeller plane of a KVLCC2 model ship in waves were measured in the towing tank by using the stereo PIV system and a phase synchronizer with heave motion. The experiment was carried out at fully loaded condition with making surge, heave and pitch motions free at a forward speed corresponding to Fr=0.142 (Re=2.55×106) in various head waves and calm water condition. The phase averaged nominal velocity fields obtained from the measurements are discussed with respect to effects of wave orbital velocity and ship motion. The low velocity region is affected by pressure gradient and ship motion.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.6
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• pp.435-445
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• 2013

One of the most challenging issues in radio frequency identification (RFID) and near field communications (NFC) is to correctly and quickly recognize a number of tag IDs in the reader's field. Unlike the probabilistic anti-collision schemes, a query tree based protocol guarantees to identify all the tags, where the distribution of tag IDs is assumed to be uniform. However, in real implements, the prefix of tag ID is uniquely assigned by the EPCglobal and the remaining part is sequentially given by a company or manufacturer. In this paper, we propose an enhanced M-ary query tree protocol (EMQT), which effectively reduces unnecessary query-response cycles between similar tag IDs using m-bit arbitration and tag expectation. The theoretical analysis and simulation results show that the EMQT significantly outperforms other schemes in terms of identification time, identification efficiency and communications overhead.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.54-61
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• 2008

This paper presents a new TIQ based CMOS flash 6-bit ADC to process digital signal in real time. In order to improve the conversion speed of ADC by designing new logic or layout of ADC circuits, a new design method is proposed in encoding logic circuits. The proposed encoding circuits convert analog input into digitally encoded double base number system(DBNS), which uses two bases unlike the normal binary representation scheme. The DBNS adopts binary and ternary radix to enhance digital arithmetic processing capability. In the DBNS, the addition and multiplication can be processed with just shift operations only. Finding near canonical representation is the most important work in general DBNS. But the main disadvantage of DBNS representation in ADC is the fan-in problem. Thus, an equal distribution algorithm is developed to solve the fan-in problem after assignment the prime numbers first. The conversion speed of simulation result was 1.6 GSPS, at 1.8V power with the Magna $0.18{\mu}m$ CMOS process, and the maximum power consumption was 38.71mW.