• Journal of IKEEE
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• v.20 no.3
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• pp.299-302
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• 2016

In this paper, we designed the stack monitoring system with improved performance. To block the incoming pulse noise to the amplifier, shield and the power supply impedance are reduced and the power circuit is isolated. The control unit is developed with variable high voltage, adaptive gain, offset and threshold in order to match the scintillation detector characteristic to the apparatus. 300-1500V variable high voltage power circuit is configured applicable to various scintillation detector. Stack monitoring system with improved performance guarantee the efficiency and the reliability by considering the characteristic of various scintillation detector. Developed stack monitoring system is evaluated with certified testing equipment and shows excellent performance with respect to the uncertainty of the sensor test results.

• Progress in Medical Physics
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• v.20 no.4
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• pp.290-297
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• 2009

In case of radiation treatment using small field high-energy photon beams, an accurate dosimetry is a challenging task because of dosimetrically unfavorable phenomena such as dramatic changes of the dose at the field boundaries, dis-equilibrium of the electrons, and non-uniformity between the detector and the phantom materials. In this study, the absorbed dose in the phantom was measured by using an ion chamber and a diode detector widely used in clinics. $GAFCHROMIC^{(R)}$ EBT films composed of water equivalent materials was also evaluated as a small field detector and compared with ionchamber and diode detectors. The output factors at 10 cm depth of a solid phantom located 100 cm from the 6 MV linear accelerator (Varian, 6 EX) source were measured for 6 field sizes ($5{\times}5\;cm^2$, $2{\times}2\;cm^2$, $1.5{\times}1.5\;cm^2$, $1{\times}1\;cm^2$, $0.7{\times}0.7\;cm^2$ and $0.5{\times}0.5\;cm^2$). As a result, from $5{\times}5\;cm^2$ to $1.5{\times}1.5\;cm^2$ field sizes, absorbed doses from three detectors were accurately identified within 1%. Wheres, the ion chamber underestimated dose compared to other detectors in the field sizes less than $1{\times}1\;cm^2$. In order to correct the observed underestimation, a convolution method was employed to eliminate the volume averaging effect of an ion chamber. Finally, in $1{\times}1\;cm^2$ field the absorbed dose with a diode detector was about 3% higher than that with the EBT film while the dose with the ion chamber after volume correction was 1% lower. For $0.5{\times}0.5\;cm^2$ field, the dose with the diode detector was 1% larger than that with the EBT film while dose with volume corrected ionization chamber was 7% lower. In conclusion, the possibility of $GAFCHROMIC^{(R)}$ EBT film as an small field dosimeter was tested and further investigation will be proceed using Monte Calro simulation.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.4
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• pp.93-102
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• 2019

As interest in wellness grows, There is a lot of research about monitoring individual health using wearable devices. Accordingly, a variety of methods have been studied to distinguish exercise from daily activities using wearable devices. Most of these existing studies are machine learning methods. However, there are problems with over-fitting on individual person's learning, data discontinuously recognition by independent segmenting and fake activity. This paper suggests a detection method for exercise activity based on the physiological response principle of heart rate up and down during exercise. This proposed method calculates activity intensity and heart rate from triaxial and photoplethysmography sensor to determine a heart rate recovery, then detects exercise by estimating activity intensity or detecting a heart rate rising state. Experimental results show that our proposed algorithm has 98.64% of averaged accuracy, 98.05% of averaged precision and 98.62% of averaged recall.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.3
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• pp.60-66
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• 2012

In this paper, we propose abandoned object detection algorithm. When abandoned object was occluded other object, the existing methods cannot detect abandoned object because those methods are not able to estimate the location of abandoned object. In order to overcome this problem, the proposed algorithm extracts the corners around abandoned object. The detected corners are linked to center of abandoned object called by supporters. We can then estimate the location of abandoned object by using supporters. Therefore, the proposed algorithm can detect and estimate the location of abandoned object, when abandoned object is occluded by other object. For this reason, the proposed algorithm can be applied to intelligent surveillance system to prevent bomb terror, which disguises as luggage or box.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.65-70
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• 2005

This paper deals with the problem of double-talk (DT) detection in anacoustic echo canceller (AEC). In the DT detection algorithm with correlation coefficient, detection errors occasionally occur because it is hard to set the threshold to distinguish DT from echo path change (EPC). Adaptive filter falls into the situation that it stops updating its filter coefficients when EPC is erroneously considered as DT at the starting-point of EPC. In addition, in case of echo path changing during the DT period, the end-point detection of DT period fails so that the AEC cannot update its filter coefficients for a while even after the DT period ends. To solve these problems, in this paper, we propose a novel AEC that employs an auxiliary filter. We use the idea that though the error signal cannot be estimated using reference signal in case or DT situation but it can be in case or EPC situation. The experimental result verifies that the proposed method could solve the problems caused by DT detection error or echo path change during the DT period.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.525-531
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• 2021

The detector of the positron emission tomography (PET) is composed using a plurality of scintillation pixels and photo sensors. The use of multiple photo sensors increases cost and complicates signal processing. In this study, a detector with reduced cost and simple signal processing was designed using a small number of photo sensors. A scintillation pixel and a small number of photo sensors were used, and a optical guide was used to deliver light to all the photo sensors. A reflector is applied to the scintillation pixel and the optical guide to transmit the maximum amount of light to the photo sensor. A diffuse reflector and a specular reflector were used for the reflector, and a flood image was obtained by applying different thicknesses of the optical guide. An optimal combination was selected through comparative analysis of the acquired flood images. As a result, when specular reflectors were used for both the scintillation pixel and the optical guide, excellent flood images were obtained from optical guides of all thicknesses. For the optical guide, the optimal image was obtained when using a 3 mm thickness in consideration of the size of the image and the analysis of the point where the image of the scintillation pixel was formed.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.5 s.311
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• pp.38-47
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• 2006

Conventional classification method uses a single classifier based on shape or motion feature. However this method exhibits a weakness if naively used since the classification performance is highly sensitive to the accuracy of moving region to be detected. The detection accuracy, in turn, depends on the condition of the image background. In this paper, we propose to resolve the drawback and thus strengthen the classification reliability by employing a Bayesian decision fusion and by optimally combining the decisions of three classifiers. The first classifier is based on shape information obtained from Fourier descriptors while the second is based on the shape information obtained from image gradients. The third classifier uses motion information. Our experimental results on the classification Performance of human and vehicle with a static camera in various directions confirm a significant improvement and indicate the superiority of the proposed decision fusion method compared to the conventional Majority Voting and Weight Average Score approaches.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.163-171
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• 2003

To evaluate the performance of the digital radiography(DR) system developed in our group, the modulation transfer function(MTF) was measured and compared with that of an analog X- ray detector, film/screen system. The DR system has an amorphous selenium(a-Se) layer vacuum-evaporated on a TFT flat panel detector. The speed class 400 film/screen (Fuji) system has been being used in the clinical field as analog X-ray detectors. Both the square wave and slit method were used to evaluate their MTF. The square method was applied to both film/screen and the DR system. The slit method, however, was applied to only DR system. The full-width half maximum resolution of film/screen was 357${\mu}{\textrm}{m}$(1.4 lp/mm at 50% spatial frequency), and the resolution of DR was limited to 200${\mu}{\textrm}{m}$(2.5 lp/mm at 30%). These results indicate the measured resolution limitations approximate to the pixel pitch, 139 ${\mu}{\textrm}{m}$ of TFT. The MTF of DR is higher than that of film/screen by the factor of 1.785. It is proved that our a-Se based DR system has potential usefulness in the clinical field.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.5
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• pp.27-37
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• 1999

A CMOS ReadOut Integrated Circuit (ROlC) for InfraRed Focal Plane Array (IRFPA) detector is presented, which is a key component in uncooled thermal imaging systems. The ROIC reads out signals from $64\times64$ Barium Strontium Titanate (BST) infrared detector array, then outputs pixel signals sequentially after amplifying and noise filtering. Various design requirements and constraints have been considered including impedance matching, low noise, low power dissipation and small detector pitch. For impedance matching between detector and pre~amplifier, a new circuit based on MOS diode structure is devised, which can be easily implemented using standard CMOS process. Also, tunable low pass filter with single~pole is used to suppress high frequency noise. In additions, a clamping circuit is adopted to enhance the signal~to-noise ratio of the readout output signals. The $64\times64$ IRFPA ROIC is designed using $0.65-\mu\textrm{m}$ 2P3M (double poly, tripple metal) N~Well CMOS process. The core part of the chip contains 62,000 devices including transistors, capacitors and resistors on an area of about $6.3-mm\times6.7-mm$.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.111-114
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• 1999

습도 제어가 안전관련분야에서 점차 그 비중이 증가하여 안전방재용 습도센서로 금수성 물질 및 기타 위험물의 저장, 핵발전소의 반응기, 고압보일러, LPG 이송 및 저장, 화학 plant 등의 습도제어 분야에 사용되고 있으며 이 외에도 섬유, 식품, 전자 등의 산업분야에서 안전 범위내의 습도 유지 및 검출을 목적으로 널리 사용된다. (중략)