• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.381.1-381.1
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• 2016

분석 방법의 간편함과 용이함의 장점은 물론, 시료 전처리 과정이 적어 시료물질의 임의 파괴나 훼손을 방지한다는 이유에서 최근 10년 간 많은 연구가 이루어지고 있는 대기압 질량분석 기술은 기압차이가 없는 대기압 분위기에서 질량분석이 이루어지기 때문에 시료를 질량분석기 입구 바로 앞에 스테이지를 설치하고서 시료를 이온화하는 경우가 대부분이다. 이 때문에 균질하지 않은 시료의 관심 영역을 모니터링하면서 질량분석을 하기에는 어려움이 있으며, 공간 정보를 추가한 질량분석 이미징에 한계가 있었다. 이에 본 연구팀은 질량분석기 입구에 챔버와 보조 펌프를 장착하여 강제로 기체 흐름 일으켜 시료로부터 발생한 이온을 질량분석기 입구로 유도하여, 원거리에서 시료를 이온화해도 질량분석기 입구까지 이온을 성공적으로 전달시키는 방법을 제안한다. 이를 이용하면 분석하고자 하는 시료를 현미경 스테이지 위에 위치시켜 분석하고자하는 부분을 현미경으로 확인하면서 질량분석을 할 수 있으며, 나아가 대기압 질량 분석 이미징 기술을 구현할 수 있다. 대기압 탈착/이온화원은시료에 열적 손상이 없는 조건으로 시편의 이온화 및 탈착 과정이 이루어지게 하기 위해 저온 대기압 헬륨 플라즈마 젯과 펨토초 레이저를 결합하여 대기압 이온화원을 제작하였다. 이온 전달관은 1/4" (6.35 mm) 외경의 60 cm 길이의 스테인리스 스틸관을 사용하여 질량분석기에서 약 60 cm 떨어진 현미경 위의 시료의 질량분석이 가능하게 했다. 보조 펌프의 계기압과 저온 대기압 헬륨 플라즈마 젯의 헬륨 기체의 유속을 변화시키면서 시료인 PDMS (polydimethylsiloxane) 의 질량 스펙트럼 (m/z 270.314) 세기를 관찰하여 최적의 이온 전달 조건을 찾았다. 추가로 현미경 스테이지에 정밀 2-D 자동 스캐닝 스테이지를 장착하여 질량분석 정보에 공간 정보를 더할 수 있는 질량분석 이미징 기술 방법을 개발하여 생체 시편의 질량분석 이미징을 얻었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.174-182
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• 2009

In this paper, we propose a novel hybrid reader antenna using a triangular and rectangular sub-patch for near- and far-field RFID reader in UHF band. The antenna operates at 912 MHz, and the low-cost mass-production is available, since the antenna can be built by printing on a FR-4 substrate. The triangular patch is designed to produce a circularly polarized radiation along the bore-sight direction and the rectangular sub-patch is designed to generate a strong magnetic field over the antenna aperture. The measurement shows Hz field greater than -25 dBA/m(3 cm above the antenna aperture), and exhibits circularly polarized radiation(AR<3 dB) with a radiation gain of 6 dBi.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.154-160
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• 2004

In this paper, implementation of active noise curtains using multiple channel adaptive filters is presented. The same numbers of single channel LMS algorithms as control loudspeakers is used instead of a multi-channel LMS algorithm to reduce the computational burden of adaptive filter algorithms. In general, a multi-channel LMS algorithm is usually used in active noise control system. but this algorithm has much more computational complexity. The single channel control techniques have less amount of DSP calculation, compared to multiple channel control techniques. A stabilizing procedure for adaptive IIR filters is also proposed to improve the stability of recursive LMS algorithms. Both experimental results of two control techniques using TMS320VC33 digital signal processor show the similar noise reduction, but the single channel control techniques are more efficient in practical active noise curtain applications

• Analytical Science and Technology
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• v.26 no.2
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• pp.120-124
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• 2013

It was studied to analyze the $CO_2$, CO, $SO_2$ standard gases of combustion gases by the open path FT-IR spectrometer with passive mode for remote analysis of air pollutant and volcano gases without IR lamp. As result, it was confirmed to have good linearity with more than 0.9 as correlation coefficients on the calibration curve of $CO_2$, CO concentration by MLR method. But in the case of $SO_2$, because the correlation coefficients were 0.88, the linearity could be lower. Finally, the concentration of three gases was predicted on in-site fire experiment under the condition of quantitative analysis. It could measure high $CO_2$ concentration as predicted result, but didn't measure the CO and $SO_2$. According to the result, it was possible to measure the combustion gases to long distance by only open path FT-IR spectrometer without infrared lamp.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.125-133
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• 2004

Most of the way shape estimation method using reference sources assume that the reference sources are in the farfield. That is, the reference sources are assumed to be far from the array. However, in applications of the array with reference sources, the reference sources are not far from the way, so that in practical ocean environments, the conventional method using farfield source model fail to estimate the positions of the hydrophones. In this paper, based on the nearfield source model, a subspace-based array shape estimation method was proposed. In the proposed method, nearfield reference source is modeled using the differential time delay at each hydrophone, and nearfield parameters are derived. Using these parameters, a subspace-based array shape estimation method that generalizes the existing farfield subspace fitting method which can work regardless of the range of the source is proposed. The Cramer-Rao lower bound for the proposed method is investigated. The results of the numerical experiments indicate that the proposed method performs well in estimating the shape of a perturbed way regardless of the ranges of the reference sources.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.155-160
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• 2001

To investigate the subjective refractive error with Von Graefe test. Maddox Rod test and polarizing lens test of Horizontal Heterophoria Measurement at distance on normal 109 subjects aged from 18 to 30 years old. The results were as follows: 1. Using Von Graefe Horizontal Heterophoria Measurement, they were measured 15% for orthophoria, 65% for exophoria and 20% for esophoria at distance. 2. Using Maddox Rod Horizontal Heterophoria Measurement, they were measured 14% for orthophoria, 57% for exophoria and 29% for esophoria at distance. 3. Using polarizing lens test of Horizontal Heterophoria Measurement, they were measured 15% for orthophoria, 72% for exophoria and 13% for esophoria at distance. 4. Each test average were $1.32{\Delta}BI$ for Von Graefe test, $0.88{\Delta}BI$ for Maddox Rod test and $1.76{\Delta}BI$ for polarizing lens test. 5. Patient's preference distribution were 44% for Von Graefe test, 28% for Maddox Rod test and 28% for polarizing lens test.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.217-223
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• 2015

This paper describes the design and implementation of a network system for UAV for multiple clients that enables long-range operation based on a commercial mobile network. A prototype data modem is developed with a commercial embedded M2M module in order to provide an access to the mobile network. A central server with a database is constructed to record all of real-time flight and video data and communicate with a ground control system. A GCS is developed for the central control, the single UAV and the smart phone version to be used for different purposes. Performance tests were progressed for data delay, video frame rate and state of clients. Flight tests were also performed to verify the reliability of the modem with respect to altitude.

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.137-142
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• 2020

Many studies based on I-vector have been conducted in a variety of environments, from text-dependent short-utterance to text-independent long-utterance. In this paper, we propose a speaker verification system employing a combination of I-vector with Probabilistic Linear Discriminant Analysis (PLDA) and speaker embedding of Long Short Term Memory (LSTM) with attention mechanism in far-field and noisy environments. The LSTM model's Equal Error Rate (EER) is 15.52 % and the Attention-LSTM model is 8.46 %, improving by 7.06 %. We show that the proposed method solves the problem of the existing extraction process which defines embedding as a heuristic. The EER of the I-vector/PLDA without combining is 6.18 % that shows the best performance. And combined with attention-LSTM based embedding is 2.57 % that is 3.61 % less than the baseline system, and which improves performance by 58.41 %.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.139-145
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• 2015

This paper proposes to increase the node energy effienciecy, which rapidly drops during the transmission of LEACH (Low Energy Adaptive Clustering Hierachy), using the method of DL-LEACH (Dual-hop Layered LEACH). By introducing dual-hop method in the data transmission, the proposed single-hop method for short-range transmission and multi-hop transmission method between the cluster heads for remote transmission was introduce. By introducing a partial multi-hop method in the data transmission, a single-hop method for short range transmission method between the cluster heads for remote transmission was introduces. In the proposed DL-LEACH, the energy consumption of cluster head for remote transmission reduces and increases the energy efficiency of sensor node by reducing the transmission distance and simplifying the transmission routine for short-range transmission. As compared the general LEACH, it was adapted to a wider sensor field.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2A
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• pp.105-112
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• 2012

Face detection at a distance faces is very challenging since images are often degraded by blurring and noise as well as low resolution. This paper proposes an improved face detection method with AdaBoost filtering and sequential testing stages with color and shape information. The conventional AdaBoost filter detects face regions but often generates false alarms. The face detection method is improved by adopting sequential testing stages in order to remove false alarms. The testing stages comprise skin-color test and variable edge-mask filtering. The skin-color filtering is composed of two steps, which involve rectangular window regions and individual pixels to generate binary face clusters. The size of the variable edge-mask is determined by the ellipse which is estimated from the face cluster. The validation of the horizontal and vertical ratio of the mask is also investigated. In the experiments, the efficacy of the proposed algorithm is proved by images captured by a CCTV and a smart-phone