• 대한치매학회지
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• 제21권4호
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• pp.126-137
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• 2022

Background and Purpose: Early detection of subjective cognitive decline (SCD) due to Alzheimer's disease (AD) is important for clinical research and effective prevention and management. This study examined if quantitative electroencephalography (qEEG) could be used for early detection of AD in SCD. Methods: Participants with SCD from 6 dementia clinics in Korea were enrolled. ¹⁸F-florbetaben brain amyloid positron emission tomography (PET) was conducted for all the participants. qEEG was performed to measure power spectrum and source cortical activity. Results: The present study included 95 participants aged over 65 years, including 26 amyloid PET (+) and 69 amyloid PET (-). In participants with amyloid PET (+), relative power at delta band was higher in frontal (p=0.025), parietal (p=0.005), and occipital (p=0.022) areas even after adjusting for age, sex, and education. Source activities of alpha 1 band were significantly decreased in the bilateral fusiform and inferior temporal areas, whereas those of delta band were increased in the bilateral cuneus, pericalcarine, lingual, lateral occipital, precuneus, posterior cingulate, and isthmus areas. There were increased connections between bilateral precuneus areas but decreased connections between left rostral middle frontal area and bilateral frontal poles at delta band in participants with amyloid PET (+) showed. At alpha 1 band, there were decreased connections between bilateral entorhinal areas after adjusting for covariates. Conclusions: SCD participants with amyloid PET (+) showed increased delta and decreased alpha 1 activity. qEEG is a potential means for predicting amyloid pathology in SCD. Further longitudinal studies are needed to confirm these findings.

• 전기전자학회논문지
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• 제24권3호
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• pp.909-912
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• 2020

본 논문에서는 IT 기술을 바탕으로 반려동물에게 맞춤형으로 케어와 훈련을 제공하는 시스템을 소개한다. 먼저 비문 인식을 통해 특정 반려동물 개체를 인식하고, 펫 로봇이 반려동물을 유도하여 훈련기로 이동시킨다. 훈련기는 간식, 놀이, 클리커 등을 통해 동물을 훈련시키며, 애드온 디바이스를 추가하여 특정 훈련에 적합하도록 쉽게 확장할 수 있다. 펫 밴드는 바이털 모니터링, 집밖 탈출 방지, 운동량 측정 등을 수행한다. 이 시스템은 구성을 변경하여 분리 불안 완화, 배변 장소 유도, 특정 장소 출입금지 등 다양한 훈련 프로그램이 가능하며, 반려동물 행동을 각 개체별로 분석하여 맞춤형 훈련을 제공한다. 또한 주인이 없을 때에도 반려동물을 적절히 운동시키고 같이 놀아주며, 반려동물의 건강에 이상이 있으면 즉시 주인에게 알려준다.

• 한국재료학회지
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• 제16권3호
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• pp.145-150
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• 2006

Various colors of light emitting diodes(LED) and four-band white light sources are obtained using a violet LED and various phosphor films. $BaMg_2Al_{16}O_{27}:Eu\;(blue),\;SrGa_2S_4:Eu\;(green),\;and\;Eu(TTA)_3(PTA)$ (red) phosphors are dispersed in poly-vinyl-alcohol aqueous solutions, and phosphor films are prepared by coating the suspensions to PET film. The narrow band emission of $Eu(TTA)_3(PTA)$ phosphor has excellent red luminescent property for four-band white light excited by the violet LED.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.228-228
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• 2008

CdS is II-VI semiconductor with a wide band gap of approximately 2.42 eV. CdS is the most popularly employed heterojunction partner to p-CdTe due to its similar chemical properties. In this work, to improvement of the surface properties of the CdS films, PET substrate is treated by high density $O_2$ plasma. CdS films are prepared by chemical bath deposition(CBD) method. In case of the PET substrate with plasma treatment for 2min, the crystalline orientation of CdS films exhibits a strong hexagonal(002). Grain size was increased from 300nm without $O_2$ plasma treatment to 380nm with an $O_2$ plasma treatment.

• Investigative Magnetic Resonance Imaging
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• 제21권3호
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• pp.162-170
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• 2017

Purpose: To evaluate the imaging findings of desmoid tumors using various imaging modalities and to evaluate whether diffusion-weighted imaging (DWI) can help differentiate between desmoid and malignant tumors. Materials and Methods: The study included 27 patients with pathologically confirmed desmoid tumors. Two radiologists reviewed 23 computed tomography (CT), 12 magnetic resonance imaging (MRI) and 8 positron emission tomography-computed tomography (PET-CT) scans of desmoid tumors and recorded data regarding the shape, multiplicity, size, location, degree of enhancement, and presence or absence of calcification or hemorrhage. The signal intensity of masses on T1- and T2-weighted imaging and the presence or absence of whirling or band-like low signal intensity on T2-weighted imaging were recorded. The apparent diffusion coefficient (ADC) values of the desmoid tumors in nine patients with DWIs were compared with the ADC values of 32 malignant tumors. The maximum standardized uptake value ($SUV_{max}$) on PET-CT images was measured in 8 patients who underwent a PET-CT. Results: The mean size of the 27 tumors was 6.77 cm (range, 2.5-26 cm) and four tumors exhibited multiplicity. The desmoid tumors were classified by shape as either mass forming (n = 18), infiltrative (n = 4), or combined (n = 5). The location of the tumors was either intra-abdominal (n = 15), within the abdominal wall (n = 8) or extra-abdominal (n = 4). Among the 27 tumors, 21 showed moderate to marked enhancement and 22 showed homogeneous enhancement. Two tumors showed calcifications and one displayed hemorrhage. Eleven of the 12 MR T2-weighted images showed whirling or band-like low signal intensity areas in the mass. The mean ADC value of the desmoid tumors ($1493{\times}10^{-6}mm^2/s$) was significantly higher than the mean of the malignant soft tissue tumors ($873{\times}10^{-6}mm^2/s$, P < 0.001). On the PET-CT images, all tumors exhibited an intermediate $SUV_{max}$ (mean, 3.7; range, 2.3-4.5). Conclusion: Desmoids tumors showed homogenous, moderate to marked enhancement on CT and MRI scans and a characteristic whirling or band-like pattern on T2-weighted images. DWI can be useful for the differentiation of desmoid tumors from malignant soft tissue tumors.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.81-86
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• 2016

Background: For positron emission tomography (PET) application, cadmium zinc telluride (CZT) has been investigated by several institutes to replace detectors from a conventional system using photomultipliers or Silicon-photomultipliers (SiPMs). The spatial and energy resolution in using CZT can be superior to current scintillator-based state-of-the-art PET detectors. CZT has been under development for several years at the Korea Atomic Energy Research Institute (KAERI) to provide a high performance gamma ray detection, which needs a single crystallinity, a good uniformity, a high stopping power, and a wide band gap. Materials and Methods: Before applying our own grown CZT detectors in the prototype PET system, we investigated preliminary research with a developed discrete type data acquisition (DAQ) system for coincident events at 128 anode pixels and two common cathodes of two CZT detectors from Redlen. Each detector has a $19.4{\times}19.4{\times}6mm^3$ volume size with a 2.2 mm anode pixel pitch. Discrete amplifiers consist of a preamplifier with a gain of $8mV{\cdot}fC^{-1}$ and noise of 55 equivalent noise charge (ENC), a $CR-RC^4$ shaping amplifier with a $5{\mu}s$ peak time, and an analog-to-digital converter (ADC) driver. The DAQ system has 65 mega-sample per second flash ADC, a self and external trigger, and a USB 3.0 interface. Results and Discussion: Characteristics such as the current-to-voltage curve, energy resolution, and electron mobility life-time products for CZT detectors are investigated. In addition, preliminary results of gamma ray imaging using 511 keV of a $^{22}Na$ gamma ray source were obtained. Conclusion: In this study, the DAQ system with a CZT radiation sensor was successfully developed and a PET image was acquired by two sets of the developed DAQ system.

• 비파괴검사학회지
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• 제26권4호
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• pp.220-230
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• 2006

3점 굽힘 하중을 받는 단일 PET 및 평판형 압전 복합재료 작동기(PCA)의 파괴거동을 음향방출(AE) 법을 이용하여 살펴보았다. 단일 PET의 경우 최대 굽힘하중에서 발생한 AE신호는 고진폭 및 긴 유지시간을 갖는 특징을 보였으며 FFT에 의한 지배 주파수 대역을 확인한 결과 $100{\sim}230kHz$의 비교적 저주파수 대역이었다. PCA의 경우, stage 1에서 발생한 80dB이상의 고진폭 및 $170{\sim}223kHz$의 저 지배 주파수 대역을 갖는 신호는 PZT층에서의 취성파괴 및 PZT층과 인근 섬유층 사이의 층간분리에 의한 것으로 추정되었다. 상기의 AE거동 해석결과와 광학현미경 및 주사전자현미경에 의한 손상관찰에 근거하여 비대칭으로 적층된 PCA의 파괴거동과 관련한 AE특성을 규명하였다.

• 한국전기전자재료학회논문지
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• 제24권5호
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• pp.355-358
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• 2011

As a II-IV compound semiconductor, ZnO has a wide band gap of 3.37 eV with transparent properties. Due to this transparent properties, ZnO materials can be also employed as the transparent conducting electrode materials. Recently, rapid progress has been made in the field of DSSC (dye sensitized solar cell)area. Therefore, strong demands have been required for the transparent electrodes with low temperature processing and cheap cost. In this paper, we will prepare ZnO thick films on the PET substrates for the electrode applications. We will investigate the structural and microstructure properties through the XRD, and SEM analysis, respectively. Also, we will study the electrical of specimens to apply the conducting electrode.

• 대한금속재료학회지
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• 제49권2호
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• pp.192-196
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• 2011

The multi-layered thin film with an ITO/Ag/ITO structure was produced on PET by using magnetron reactive sputtering method. First, 30 nm of ITO thin film was coated on PET by using normal temperature process. Then 20-52 nm of the Ag thin film was coated. Lastly, 30 nm of ITO thin film was coated on Ag layer. The sample of the 20 nm Ag thin film showed more than 70% transmission and a $2.7{\Omega}/{\Box}$ sheet resistance. When compared to the existing single-layered transparent conducting thin film, multi-layered film was found to be superior with about $5{\Omega}/{\Box}$ less sheet resistance. However, since the Ag layer became thinner, the band gap energy needs to be increased to more than 3.5 eV.

• 한국통신학회논문지
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• 제34권12B호
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• pp.1452-1458
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• 2009

본 논문에서는 다기능 복합 카드용 극초단파(UHF) 대역 소형 태그 안테나를 제안하였다. 현재 일반적으로 HF 대역 태그와 UHF 대역 태그가 장착된 듀얼 카드가 사용되고 있다. 본 논문에서는 기존 듀얼 카드에 지문인식 시스템이 탑재됨으로써 발생하는 공간상 제약 및 주변 도체로 인한 RFID 태그 인식거리 성능 저하를 최소화한 다기능 복합 카드용 극초단파 대역 RFID 소형 태그 안테나를 제안하였다. 제안된 극초단파 대역 RFID 소형 태그 안테나는 HF 태그 및 지문인식 시스템이 탑재된 제한된 공간에 적용 가능한 다기능 복합 카드용이며 테이퍼트, 미앤더 라인 및 루프 구조를 변형시킴으로써 소형화 및 태그 칩 매칭을 가능하게 하였다. 제안된 소형 태그 안테나는 카드 재질 특성 및 주변 회로를 감안하여 설계하였으며 작은 크기($50{\times}15\;mm^2$)로 PET필름에 제작 되었다. RFID 소형 태그 측정 방법은 무반사실에서 EPCglobal Static Test 장비를 이용하여 측정하였으며 기존 사용 중인 듀얼 카드와 차량 내부 및 지갑을 이용해서 다양한 비교 측정을 하였다. 측정 결과 EPCglobal Static Test 결과 인식거리는 3.8 m, 필드테스트 결과 차량 내부에서 최대 인식거리 7.6 m로 양호한 결과를 확인하였으며 제안된 태그 안테나는 지자체에서 주차통제보안시스템에 사용될 예정이다.