• Horticultural Science & Technology
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• v.17 no.2
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• pp.127-130
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• 1999

This study was attempted to develop the algorithm for recognizing fruits acquired from apple tree images with digital camera in sunlight. As the result of L*a*b* color transformation for reducing the effect of sunlight, a* and b* color index were effective to extract apple pixels in tree images and linear discrimination functions with color index a* b* were developed. To recognize fruits from apple pixels, those were classified into 4 patterns according to clustering condition and morphologically filtered. Test results showed that apple fruits unoccluded were exactly recognized, whereas apple fruits occluded with leaves and trunk were miscounted 2 apples on average.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.254-262
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• 2010

In order to evaluate vibration serviceability by means of non-contact vibration meter, serviceability of existing bridge were experimentally evaluated by using laser vibration meter. Test results were analyzed and compared with evaluation results acquired by using accelerometer and LVDT. To testify accuracy of laser vibration meter measured natural frequency were compared with that acquired by using accelerometer. According to test and comparison results it is showed that serviceability can be evaluated properly enough from the tolerance curve of Reiher-Meister for the estimated acceleration that can be calculated by the numerical differentiation of measured velocity. But because of cumulative numerical error occurred during integration of measured velocity in the time domain serviceability grade could be different from the result acquired by LVDT.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.170-178
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• 2004

This paper deals with six degree-of-freedom HILS(hardware-in-the-loop-simulation) of KSR-III rocket using a TAFMS(three axis flight motion simulator). This TAFMS HILS test is accomplished before main HILS tests in order to verify the control stability in the presence of TAFMS dynamic effects. The TAFMS HILS test includes initial attitude holding tests for INS initial alignment procedures, timer synchronization tests with an auxiliary lift-off signal, real-time calibration tests using an external thermal recorder, open-loop TAFMS operating tests, and final closed-loop TAFMS HILS tests using the TAFMS attitude measurements as inputs to the closed control loop. The HILS tests are accomplished for several flight conditions composed with nominal flight condition, TWD effect added condition, slosh modes and/or bending modes existing condition, and windy condition, etc.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.85-95
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• 1995

Radiation measuring system using wireless communication method with single channel has been diveloped and tested. In this system, radiation signals from GM tube are transformed into digital pulses in pulse processing circuit and modulated in FSK (frequency shift keying) circuit for digital communication and then wirelessly transmitted to a receiving unit. The digital pulses received are then demodulated in FSK circuit and converted into radiation dose/dose rate in the data acquisition unit to display on the screen of a personal computer. The performance of this system was evaluated by using both a pulse generator and a standard radiation source(Cs-137). In both cases, digital pulses with 5V were observed in pulse processing circuit without distortion of their shape through wireless communication system. The experimental results of radiation measurement by this system after several test-irradiation of GM detector to a standard radiation source(Cs-137), showed good agreement with irradiation dose rate within 10% difference, and proved that this system could be effectively utillized as radiation measuring instrument. It is expected that this wireless radiation measuring system developed for the first time in Korea, can be used as a radiation monitor as well as a personal dosimeter if we can further improve this system to adopt wireless multichannel communication system.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.59-68
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• 2008

In this paper, we propose a method for selecting meaningful event packets from which can receive before anything else from seismograph according to allotted priority and estimate epicenter using selected packets. Event packets which received from each station will be evaluated with their onset time, signal period and SNR by statistical method and will be selected packets related with real earthquake's P-wave. And estimated epicenters using by 'Application of epicenter estimation using first P arrivals'. With local earthquakes occurred in 2007 were announced by KMA, collected event packets on earthquake happened date and selected p-wave related packets and estimated epicenter. After result of experiment, if an earthquake occurred within seismic networks, can estimate epicenter with small misfits just after event packets arrived from above 4 stations. Considering average distance of each station, in case of using all stations' data include other organization, can estimate and alert rapidly. It show this method is useful when construct a local earthquake early warning system later.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.196-202
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• 2017

A very long test track is required for high-speed operation test of the real-scale Linear Synchronous Motor (LSM) for ultra-high-speed trains. The required length results in huge construction cost and economic loss if any error occurs during development. Therefore, validation study of the LSM design technology using a low-cost small-scale model must be carried out in the early research stages. It is possible to deduce an optimal winding method for the armature and determine the mechanical properties of the LSM through a performance tester that applies a rotary-type small-scale LSM model. In addition, it is possible to utilize previous research on LSM control systems. Therefore, a basic design model, comprising a rotary-type LSM tester that meets the requirements for the propulsion of 600km/h-class ultra-high-speed trains, is derived in this study. Finally, an optimal model, which has a stable structure under the condition of 1500rpm or more high-speed rotation, is derived by electromagnetic and mechanical stiffness analysis.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.447-451
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• 2007

A triplexer based on a silica planar lightwave circuit Mach-Zehnder nterferometer(MZI) is proposed and its characteristics are analyzed through simulations. To separate 1310 nm band and $1480{\sim}1560nm$ band properly, the path length difference of an MZI is set to be the multiple and half of the wavelength 1310 nm and the balance of the directional coupler is optimized in the $1480{\sim}1560nm$ band. The same MZI is additionally cascaded to provide good crosstalk characteristics. The 1490 nm band and 1550 nm band are further separated using additional two stage MZI's. A three-dimensional BPM and transfer matrix method analysis predicts the low crosstalk characteristics and the fabrication-error-tolerance of the proposed triplexer.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.346-352
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• 2012

Radiation dose estimation on the newborn and infants during radiation examinations, unlike for the adults, is not actively being progressed. Therefore, as an index to present exposure dose during radiation examinations on newborn and infants, entrance skin dose was measured, and the result was compared with results of monte carlo simulation to raise reproducibility of entrance skin dose measurement, and it was proved that various geometry implementation was possible. The resulting values through monte carlo simulation was estimated using normalization factors for entrance skin dose to calibrate radiation dose and then normalized to a unit X ray radiation field size. Average entrance skin dose per one time exposure was $78.41{\mu}Gy$ and the percentage error between measurement by dosimeter and by monte carlo simulation was found to be -4.77%. Entrance skin dose assessment by monte carlo simulation provides possible alternative method in difficult entrance skin dose estimation for the newborn and infants who visit hospital for actual diagnosis.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.35-43
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• 2013

Exercise such as walking is helpful to manage one's own weight and to counter life habit diseases such as obesity. Calorie consumption is usually calculated based on the distance walked. One way to measure the distance is by using steps and stride length. Most pedometers, including some applications in smart devices, are inaccurate, because they use a common value as the average stride length, even though each person has a different stride length. Moreover, the stride length differs depending on the walking pace, which will further increase the error. To address this, in this paper, I classify paces into three categories. Following that, I introduce a customized measurement of stride length, which is calculated based on the stride length corresponding to each pace category after obtaining x, y, z values from a 3-axis accelerometer in the smart device. In addition to this, I developed an application running on the smart device designed for the proposed measurement of stride. I have conducted three experiments for the assessment of the proposed measurement. In conclusion, I confirmed the effectiveness of this system.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.34-39
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• 2007

Super-REsolution Near-field Structure (Super-RENS) 재생 현상을 모델링하고 재생 신호를 계산하여 실험 결과와 비교하였다. 약 2mW 내외의 높은 광 파워로 집광된 Spot 은 디스크 내의 상변화 물질인 GST 를 용융시키므로 집광 Spot 내에는 용융 영역과 비 용융 영역이 공존하게 되고 연속적 또는 불연속적인 경계를 이루게 된다. 이러한 열 효과로부터 기인하는 집광 Spot 내에서의 물질의 광학적 특성 변화와 변화 정도의 차이를 가정하였고 변화된 광학적 특성은 집광된 Spot 의 유효 크기를 줄어들게 함으로써 회절한계 이하의 정보를 재생 가능하게 한다. 계산은 FDTD 방법과 Scalar 방법을 병행하였다. FDTD 방법으로는 위와 같은 집광 Spot 내의 물질 굴절률 (n,k) 변화로부터 회절한계 이하의 정보가 재생 가능함과 CNR 문턱 현상을 확인하였고, Scalar 방법으로는 물질 굴절률을 직접 다루지 않고 굴절률 변화로부터 기인하는 광의 Amplitude 와 Phase 변화로부터 회절한계 이하의 정보가 재생 가능함을 확인하였다. 이 때 광의 Amplitude 와 Phase 변화를 모델링하기 위하여 지름, 위치, 반사율 변화량, 위상 변화량의 네가지 변수로 정의되는 광 마스크를 도입하였다. Scalar 방법을 이용하여 재생 RF 신호 등 다양한 Super-RENS 디스크의 신호를 계산 활용 할 수 있고 다음의 두가지 광학계에 대하여 계산과 실험으로 얻은 채널 특성 및 RF 신호를 비교하여 각각 오차평균 4.2%, 4.7%로 일치함을 확인하였다. 파장 659nm, NA=0.6, Min Pit Length=173nm ROM 디스크 System, 파장 405nm, NA=0.85 Min Mark Length=75nm WORM 디스크 System.