• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2002.05a
• /
• pp.148-151
• /
• 2002

본 연구에서는 Ca, In, V, Al을 첨가 원소로 사용한 YIG 페라이트 분말을 분무건조기로 준구형 과립으로 만들어 일반적인 세라믹 제조 공정 방법으로 다결정 테를 제조하였고, 소결온도와 첨가원소의 조성비에 따른 YIG 페라이트의 기본물성과 전자기적 특성 변화를 조사하였다. 제조된 YIG 페라이트에 대한 기본 물성과 자기 특성을 밀도측정기, XRD, SEM, VSM, Network Analyzer 등을 이용하여 측정 분석하였다. $Y_{2.1}$C $a_{0.9}$F $e_{4.4}$ $V_{0.5}$I $n_{0.05}$A $l_{0.05}$ $O_{12}$ 조성의 YIG 페라이트에 대한 전자기적 특성 측정 결과 13$50^{\circ}C$에서 소결한 YIG 페라이트에서 우수한 삽입손실 값과 Isolation 값을 나타내였으며 이론밀도의 92%의 높은 밀도값을 가지며 높은 포화자화(4$\pi$Ms) 값을 지닌 우수한 전자기적 특성을 나타내었다.내었다.내었다.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2011.06a
• /
• pp.355-358
• /
• 2011

본 논문에서는 이미지에서 사용자가 관심을 갖는 영역(ROI)의 내용을 나타내는 특성값과 영역의 위치를 함께 고려하여 이미지를 검색하는 방법을 제안한다. 제안한 방법은 검색 대상 이미지를 일정 크기의 블록으로 구분한 후 사용자가 선택한 다중 ROI와 가장 근접하는 특성을 가진 블록을 선택한다. 블록의 특성값은 MPEG-7의 도미넌트 컬러 기술자를 사용한다. 사용자가 선택한 블록의 특성값과 함께 블록의 위치를 측정한 후, 검색 대상 이미지의 블록들의 특성값 및 위치와 비교하여 유사도를 측정한다. 본 논문에서는 실험결과 제안한 방법이 전역 이미지 검색이나 동일한 위치의 블록만 비교하는 경우보다 다중 ROI의 내용과 위치를 함께 고려하는 방법이 다른 방법에 비해 우수한 성능을 나타냈다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.11a
• /
• pp.607-608
• /
• 2009

최근 7.7 DDoS 대란과 폭발적인 SPAM 발송과 같은 다양한 봇넷의 악성행위는 정보 시스템에 막대한 악영향을 미친다. 특히, 봇넷의 구조적 특징인 좀비PC의 제어는 네트워크 환경에서는 다양한 악성 행위를 유발한다. 때문에, 봇넷 탐지와 관련한 다양한 연구가 시도되었지만, 탐지의 한계점을 지니고 있다. 즉, 기존의 봇넷 탐지 방법은 임의의 임계값을 설정하고, 그 값을 벗어나는 시점에서 경고를 보내어 탐지하게 된다. 하지만, 전문가에 의한 임계값 설정은 자칫 오탐율과 미탐율을 야기할 수 있다. 따라서, 본 논문에서는 봇넷 탐지를 보다 능동적으로 하기 위하여 특정 타임 윈도우 구간동안의 봇넷이 유발하는 네트워크 트래픽을 분석하고 마르코프 체인을 응용한 학습을 하여 능동적으로 적용 가능한 임계값을 측정 방법론에 대하여 고찰하고자 한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.2
• /
• pp.46-54
• /
• 1999

In recent years, the electromagnetic enviroments are varied with the increase of power consumption and the spread of hoosehold electric appliances. Most of the interests to date have concentrated in the area of human health effects associated with exposure to power frequency electric and rmgretic fields, and thus the precise measurement and analysis are required. In this paper, the measurements and analysis of the extremdy low frequency(ElF) electric and magnetic fields produced by actual 22.9[kV] distribution lines were performed. The experiIrents have been carried rot by lateral rrofile, and the thooretical analyses were made by use of FIELDS program fer the sake of comparison with the experimental data. Electric and magnetic field intensity were strong under power distrib.rticn lines, and were inversely proportional to lateral distance. The pufiles of electric and magnetic fields were M and $\bigcap$ shapes, respectively. and the rreasured data were good in agreemnt with the thooretical results. Both the electric and magnetic field intensity were iocreased with increasing the measurement height.height.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.1
• /
• pp.175-184
• /
• 2016

In this paper, we propose the method to measure the capacitances using not LCR meter but capacitance to voltage(C/V) conversion. And we design the analog MUX circuits that convert 192 channels to 6 MUX channels in order to implement the diagnosis of multi-channel ultrasonic probe. This paper derives the conversion function that converts the digital voltage of each MUX channel to the capacitance using the least squares method because the circuit characteristics that convert the voltage of each MUX channel to the capacitance are different. The developed prototype illustrates the performance test results that the measure times are measured by within 4sec and the measure error rates of maximum, minimum, and average values are within 5% in terms of the repeated measurements of all 192 channels.

• Journal of Korea Multimedia Society
• /
• v.12 no.3
• /
• pp.383-396
• /
• 2009

Bone age assessment has been widely used in pediatrics to identify endocrine problems of children. Since the number of trained doctors is far less than the demands, there has been numerous requests for automatic estimation of bone age. Therefore, in this paper, we propose an automatic bone age assessment method that utilizes pattern classification techniques. The proposed method consists of three modules; a finger segmentation module, a normalized shape model generation module and a bone age estimation module. The finger segmentation module segments fingers and epiphyseal regions by means of various image processing algorithms. The shape model abstraction module employ ASM to improves the accuracy of feature extraction for bone age estimation. In addition, SVM is used for estimation of bone age. Features for the estimation include the length of bone and the ratios of bone length. We evaluated the performance of the proposed method through statistical analysis by comparing the bone age assessment results by clinical experts and the proposed automatic method. Through the experimental results, the mean error of the assessment was 0.679 year, which was better than the average error acceptable in clinical practice.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.10
• /
• pp.4673-4678
• /
• 2011

In this paper, studies on a mixing characteristic and viscosity measurement of polymer/graphite composites for a bipolar plate of the polymer electrolyte membrane fuel cell were presented. Since the materials for the bipolar plate should be electrically conductive, contents of solid graphite in the composite are very high. As a consequence, a viscosity of the polymer/graphite composite used for the bipolar plate is very high and the measurement of the viscosity is difficult. Viscosity measurements of the polymer/graphite composites were not possible because pressure drops were continuously fluctuated during the viscosity measurements when a conventional capillary die was used. After the die design was optimized, the steady state pressure drop could be achieved, but the viscosity thus measured was not reproducible. After many trials with different experimental techniques, it was found that melt blending of the grinded powder mixtures of both PET and graphite provides reproducible viscosity measurements and electric conductivities of the polymer/graphite composites.

• Journal of the Korean Society for Railway
• /
• v.20 no.4
• /
• pp.440-447
• /
• 2017

Spectrum level for the acoustic roughness of wheels and rail surface should be periodically maintained under the limitation of ISO to reduce rolling noise of railway vehicles. Thus, in maintaining railway track, displacement sensor-based measuring devices are broadly used to measure the surface roughness and to perform spectral analysis. However, these measuring devices cause unexpected measuring errors since the displacement sensors are fixed at moving platforms and the main frame produces pitching motion during measurement. To increase the accuracy of the measured values, this paper has investigated the effects of design variables such as wheel base, additional wheels, and elastic deformation of wheels on the surface roughness and acoustic roughness spectrum.

• Korean Chemical Engineering Research
• /
• v.60 no.4
• /
• pp.557-563
• /
• 2022

In order to measure the allergen penetration of micropore fabrics, it is necessary to develop a convenient and appropriate experimental method for measuring a pore size of micropore fabrics. In this study, a simple and economical experimental apparatus was developed for the analysis of the pore size of micropore fabrics by measuring the weight reduction rate. In addition, the allergen blocking properties was evaluated by measuring the pore sizes of various fabrics. According to this study, the size of the pores of the microporous fabric could be obtained by measuring the weight reduction rates. In addition, higher weight reduction rate was obtained as the suction pressure passing through the particle permeation device decreased and the suction time was increased. It is expected that the developed experimental method and apparatus can be utilized as an experimental standard for quality control methods to verify the effectiveness of micropore fabrics used for house dust mite blocking bedding.

• The Journal of Korean Society for Radiation Therapy
• /
• v.27 no.1
• /
• pp.13-22
• /
• 2015

Purpose : We investigated the safety of Intrabeam$^{TM}$ system, X-ray unit for Intraoperative Radiotheray (IORT) by measuring surface dose using Optically Stimulated Luminescent Dosimeter(OSLD). Materials and Methods : 30 patients were selected, who were in breast cancer patients and had an operation of breast conserving surgery (BCS). At the inner surface of tumor bed, 20 Gy were described, and 5 Gy at 1cm depth from the inner surface. Along the size of tumor bed which could be decided after resection of tumor, the size of applicator were determined. Usual treatment time were from 18 to 40 minutes. For the measurement of surface doses, OSLD were placed at superior(U1,2), inferior(D1,2), lateral(L1,2) and medial(M1,2) directions from the center of applicator. Each direction, two OSLD were placed at 0.5 cm and 1.5 cm from the center. Mean, maximum, and minimum doses were analyzed to be compared. Results : Mean values were U1 $2.23{\pm}0.80Gy$, U2 $1.54{\pm}0.53Gy$, D1 $1.73{\pm}0.63Gy$, D2 $1.25{\pm}0.45Gy$, L1 $1.95{\pm}0.82Gy$, L2 $1.38{\pm}0.42Gy$, M1 $2.03{\pm}0.70Gy$, and M2 $1.51{\pm}0.58Gy$. Maximum values were 4.34 Gy at U1, and Minimum values were 0.45 Gy at M2. 13.3 % of patient (4pts out of 30) were reported that surface dose were over 4 Gy. Conclusion : The fact that skin dose of all patients were less than 5 Gy based on OSLD measurement showed the safety of Intrabeam$^{TM}$ system. In the relatively small breast volume, the tendency that surface dose was increased had been shown, which was analyzed by the data of patients who irradiated over 4Gy at skin surface. Therefore, for appropriate indication for IORT, it is suggested that breast volume as well as the size and position of tumor should be carfully considered.