• Journal of Radiation Protection and Research
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• v.25 no.4
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• pp.197-205
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• 2000

A prototype electronic dosimeter(PED) adopting a silicon PIN diode detector as a radiation detector has been developed, manufactured and test-evaluated. A radiation signal processing circuit has been electronically tested and then the radiation detection characteristics of this PED has been performance-tested by using a reference photon radiation field. As a result in a electronic performance test, radiation signals from a detector were well observed in the signal processing circuit. The radiation detection sensitivity of this PED after several test-irradiations to $^{137}Cs$ gamma radiation source appeared to be 1.85 cps/$Gy{\cdot}h^{-1}$ with 19.3% of the coefficient of variation, which satisfied the performance criteria for the active personnel radiation monitor. Further improvement of the electronic circuit and operating program will enable the PED to be used in personal monitoring purpose.

• Electronics and Telecommunications Trends
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• v.21 no.5 s.101
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• pp.109-118
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• 2006

조셉슨 터널접합을 사용한 초전도 혼합기 또는 믹서(SIS mixer)와 매우 얇은 초전도박막을 이용한 초전도 혼합기(HEB mixer)는 초전도 현상에 있어서의 거시적 양자효과를 유발하는 강한 비선형성을 가지기 때문에, 종래의 전자파 검출기로는 구현이 어렵고 또한 극도로 낮은 잡음특성을 실현한다. 테라헤르츠(THz) 주파수 영역용 고감도검출기로서도 기대되는 질화니오븀(NbN) 박막을 사용한 SIS 혼합기와 HEB 혼합기의 개발현황과 연구결과에 대하여 소개하고자 한다. 그리고 최근에 많이 연구되고 있는 펨토초레이저와 고온초전도 상호작용을 이용한 테라헤르츠 연구결과도 소개한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.3-9
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• 2013

This paper proposes a selective-weighted energy detection (S-WED) and a synchronization algorithm appropriate for it in IR-UWB system. Energy detectors that are practical in terms of implementation are employed widely for noncoherent reception in IR-UWB systems. However, they show low performance due to using the energy samples captured at symbol rate. For this reason, weighted energy detectors are developed to improve the performance of EDs. Hence, for WED, not only synchronization but also the weight coefficients are needed to be obtained prior to data detection. Meanwhile, the optimal weighting coefficients of WEDs are known to be energy values. Therefore, synchronization and the weighting coefficients can be obtained simultaneously. This paper proposes an S-WED and a simple synchronization algorithm for it in which sub-intervals having energies under a certain level are excluded in energy accumulation resulting in a simpler WED with a bit performance increase in low SNR region. The proposed algorithm is verified through simulations using the preamble symbol and channel models defined in the IEEE 802.15.4a.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.28-33
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• 2006

An integrated 3.125Gbps clock and data recovery (CDR) circuit is presented. The circuit does not need a reference clock. It has a phase and frequency detector (PFD), which incorporates a bang-bang type 4X oversampling PD and a rotational frequency detector (FD). It also has a ring oscillator type VCO with four delay stages and three zero-offset charge pumps. With a proposed PD and m, the tracking range of 24% can be achieved. Experimental results show that the circuit is capable of recovering clock and data at rates of 3.125Gbps with 0.18 um CMOS technology. The measured recovered clock jitter (p-p) is about 14ps. The CDR has 1.8volt single power supply. The power dissipation is about 140mW.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.60.1-60.1
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• 2021

현재 중력파 관측은 레이저 간섭계 기반의 중력파 검출기를 통해 이루어지고 있고 검출기 성능이 개선되고 안정화 되어 초기 설계 사양 이상의 관측감도를 확보하였다. 이제 레이저 간섭계 기반의 중력파 관측 기술은 중력파 관측 가능성의 유무를 넘어 차세대 중력파 검출기의 건설을 앞당기는 수준이 되었으며 해외에서는 중력파 검출 기술을 선도하기 위한 공격적인 투자가 이루어 지고 있다. 이 발표에서는 현재 운영중인 레이저 간섭계 기반의 중력파 검출기의 중력파 검출 원리와 실제 중력파 검출기에서 사용되는 관련 핵심 기술들을 소개하고자 한다. 단순히 특정 분야의 일부 기술이 아닌 중력파 검출기 건설에 사용된 재료, 광학, 기계공학, 전자, 통신 등 다양한 분야의 기술을 소개하고 실제 중력파 검출기 관련 연구에 참여할 수 있는 연구 주제를 소개하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.72-77
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• 2008

In this paper, we propose a novel structure where the energy detector has multiples of verification using time delay in order to improve its performance. Additionally, the performance is investigated by simulation and compared to that of the original energy detector. The simulation result shows that the proposed scheme improves the performance when SNR is compared with the mis-detection probability for both 1% and 10% of false alarm probability. The performance is also described in terms of ROC.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.2
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• pp.44-54
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• 1985

The high resolution of positron emission tomography, in particular, requires the use of detector crystals of narrow width but still with sufficiently high detection efficiency. If the crystal width is reduced to several millimeters, degradation of detection efficiency and leakage coefficient becomes significant, particularly in case of obliquely incident photons. Alleviation of such a problem can be made possible by modification of the detector shape from the conventional rectangular type to a wed농e type. The Proposed wedge shape makes the absorption length longer for obliquely incident photons, thus increasing the detection efficiency and suppressing leakage coefficient. For the BGO detectors of 4-8mm width, the computer simulation result of the system using wedge detectors reveals resolution improvement to the system using conventional detectors. For the system composed of 200 BGO detectors of 8mm width with 2 point sampling motion, the simulation resolution system using conventional detectors. For the very high resolution system of 3-7mm FWHM, the characteristics of the detector shape and size is studied by computer simulation.

• Journal of IKEEE
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• v.23 no.1
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• pp.266-272
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• 2019

Multicopters have become more popular since they are advantageous in their ability to take off and land vertically. In order to guarantee the normal operations of such multicopters, the problem of fault detection and isolation is very important. In this paper, a new method for detecting and isolating an actuator fault of a hexacopter is proposed based on the analytical approach. The residual is newly defined using the angular velocities of actuators estimated by the mathematical model and an actuator fault is detected comparing the residuals to a threshold. And a fault is isolated combining a dynamic model and generated residuals when a fault is detected. The proposed method is a simple, but effective technique because it is based on mathematical model. The results of the computer simulation are also given to demonstrate the validity of the proposed algorithm in case of a single failure.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.2
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• pp.11-20
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• 2010

In this paper we propose a face detection system which consists of a method of face candidate extraction using skin color and a method of face verification using the feature of facial structure. Firstly, the proposed extraction method of face candidate uses the image segmentation and merging algorithm in the regions of skin color and the neighboring regions of skin color. These two algorithms make it possible to select the face candidates from the variety of faces in the image with complicated backgrounds. Secondly, by using the partial face classifier, the proposed face validation method verifies the feature of face structure and then classifies face and non-face. This classifier uses face images only in the learning process and does not consider non-face images in order to use less number of training images. In the experimental, the proposed method of face candidate extraction can find more 9.55% faces on average as face candidates than other methods. Also in the experiment of face and non-face classification, the proposed face validation method obtains the face classification rate on the average 4.97% higher than other face/non-face classifiers when the non-face classification rate is about 99%.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.92-94
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• 2018

본 논문은 SiC MOSFET 디바이스를 사용하는 전력변환장치에서 Rogowski 코일을 이용하여 SiC MOSFET 디바이스에 흐르는 전류를 측정하여, 과전류를 검출하고 게이팅 신호를 차단하는 기법에 관하여 연구한다. SiC MOSFET는 소자의 특성으로 보편적으로 사용되는 과전류 검출 방법인 DeSAT 적용이 어렵기 때문에 Rogowski 코일을 사용하여 스위치 전류를 측정, 과전류를 검출한다. 본 논문에서는 PCB패턴 Rogowski 코일의 설계 방법뿐만 아니라 Rogowski 코일과 적분기의 대역폭에 대해서도 논의한다. 실험은 직류링크 커패시터에 SiC MOSFET 스위치 레그를 병렬로 연결하고, 직류링크 커패시터에 직류전압을 충전 후 스위치 레그를 약 6us정도 단락시켜 SiC MOSFET에 과전류를 발생시킨다. 이 때, 제안한 Rogowski 코일을 이용한 과전류 검출 및 차단 기법의 적용 전후를 비교하여 동작 및 성능(검출 및 차단 소요시간)을 확인한다. 마지막으로 실험 결과를 통해 본 논문에서 제안한 PCB패턴 Rogowski 코일을 이용하여 과전류 검출 및 차단 기법이 검증되었다.