• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.182-184
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• 2018

본 논문에서는 HDR 영상 신호의 고속 광전변환을 위한 파라미터 룩업 테이블 기반 구간 선형 근사 방법을 제안한다. 제안하는 방법은 고속화하기 위한 광전변환함수의 입력 값의 범위를 다수개의 구간으로 나누고 각 구간마다 별도의 선형 근사함수를 구하여 광전변환함수를 근사하고 각 구간별로 필요한 선형 근사함수의 파라미터를 룩업 테이블에 미리 저장하고 사용함으로써 보다 빠른 근사 값 계산이 가능하다. 제안한 방법의 성능 평가를 위해 MPEG 에서 제공하는 참조 소프트웨어인 HDRTools 를 기반으로 실험을 수행했고 이를 통해 참조 소프트웨어에 구현되어 있는 기존의 고속화 방법과 비교하여 더 적은 연산 수를 가지며 평균 24% 빠른 처리속도와 약 0.05dB 의 평균 PSNR 손실을 보임을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.156-157
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• 2018

최근 가정용 TV 를 포함한 비디오 디스플레이 기기는 HD(High Definition)에서 UHD(Ultra High Definition)로 급속하게 전환되고 있다. DTV 방송의 경우 한국은 HDR(High Dynamic Range)이 제외된 UHDTV 지상파 방송을 시작하였고 북미 MVPD(Multiple Video Program Distributor) 사업자들은 HDR 서비스를 먼저 도입하기 시작하였다. 기존 full HD 보다 4 배 이상의 해상도를 지원하는 UHD 는 HDR 과 WCG(Wide Color Gamuit)를 제외하고 논할 수 없다. 본 고에서는 해외의 디스플레이 인증 기관에서 적용하고 있는 UHD 디스플레이 디바이스에 대한 화질 평가 기술에 대하여 소개한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.70-73
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• 2021

최근 영상 및 비디오 분야에 심층 신경망(DNN, Deep Neural Network)을 사용한 연구가 다양하게 진행됨에 따라 High Dynamic Range (HDR) 이미징 기술에서도 기존의 방법들 보다 우수한 성능을 보이는 심층 신경망 모델들이 등장하였다. 하지만, 심층 신경망을 사용한 방법은 큰 연산량과 많은 GPU 메모리를 사용한다는 문제점이 존재하며, 이는 심층 신경망 기반 기술들의 현실 적용 가능성에 제한이 되고 있다. 이에 본 논문에서는 제한된 연산량과 GPU 메모리 조건에서도 사용 가능한 다중 노출 HDR 경량화 심층 신경망을 제안한다. Kalantari Dataset에 대해 기존 HDR 모델들과의 성능 평가를 진행해 본 결과, PSNR-µ와 PSNR-l 수치에서 GPU 메모리 사용량 대비 우수한 성능을 보임을 확인하였다.

• Radiation Oncology Journal
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• v.20 no.4
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• pp.396-404
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• 2002

Purpose : Many papers support a correlation between rectal complications and rectal doses in uterine cervical cancer patients treated with radical radiotherapy. In vivo dosimetry in the rectum following the ICRU report 38 contributes to the quality assurance in HDR brachytherapy, especially in minimizing side effects. This study compares the rectal doses calculated in the radiation treatment planning system to that measured with a silicon diode the in vivo dosimetry system. Methods : Nine patients, with a uterine cervical carcinoma, treated with Iridium-192 high dose rate brachytherapy between June 2001 and Feb. 2002, were retrospectively analysed. Six to eight-fractions of high dose rate (HDR)-intracavitary radiotherapy (ICR) were delivered two times per week, with a total dose of $28\~32\;Gy$ to point A. In 44 applications, to the 9 patients, the measured rectal doses were analyzed and compared with the calculated rectal doses using the radiation treatment planning system. Using graphic approximation methods, in conjunction with localization radiographs, the expected dose values at the detector points of an intrarectal semiconductor dosimeter, were calculated. Results : There were significant differences between the calculated rectal doses, based on the simulation radiographs, and the calculated rectal doses, based on the radiographs in each fraction of the HDR ICR. Also, there were significant differences between the calculated and measured rectal doses based on the in-vivo diode dosimetry system. The rectal reference point on the anteroposterior line drawn through the lower end of the uterine sources, according to ICRU 38 report, received the maximum rectal doses in only 2 out of the nine patients $(22.2\%)$. Conclusion : In HDR ICR planning for conical cancer, optimization of the dose to the rectum by the computer-assisted planning system, using radiographs in simulation, is improper. This study showed that in vivo rectal dosimetry, using a diode detector during the HDR ICR, could have a useful role in quality control for HDR brachytherapy in cervical carcinomas. The importance of individual dosimeters for each HDR ICR is clear. In some departments that do not have the in vivo dosimetry system, the radiation oncologist has to find, from lateral fluoroscopic findings, the location of the rectal marker before each fractionated HDR brachytherapy, which is a necessary and important step of HDR brachytherapy for cervical cancer.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.68-76
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• 1998

Background: Patients with centrally recurred bronchogenic carcinoma make a complaint of many symptoms like hemoptysis, cough & dyspnea. At these conditions, the goal of treatment is only to relieve their symptoms. High dose rate brachytherapy(HDR-BT) is the palliative treatment modality of centrally located endobronchial tumor regardless of previous external irradiation(XRT) on the same site in symptomatic patients. Methods: We studied the effects of HDR-BT in 26 patients with symptomatic recurrent lung cancer. Patients(male: 24, mean age: 54yrs)were treated with HDR-BT underwent bronchoscopic placement of $^{192}Ir$ HDR after loading unit(Gammamed$^{(T)}$, Germany) to deliver 500cGY intraluminal irradiation at a depth of 1cm every lwk on 3 occasions. Evaluation at base line and 4wks after HDR brachytherapy included chest X-ray, bronchscopy, symptoms (Standadized Scale for dyspnea,cough,hemoptysis), and Karnofsky performance scale. Results: Endobronchial obstruction was improved in 11/26 patients(37%). Atelectasis in chest X-ray was improved in 5/15 patients(33%). Hemoptysis, dyspnea & cough were improved in 5/10 patients (50%), 5/8 patients (62%) & 10/18 patients (56%) respectively. Karnofsky performance status was changed from 76.4 scores in pretreatment to 77.6 scores after treatment. During HDR-BT, massive hemoptysis (2 patients) and pneumothorax(1 patient) were occurred as complications. Conclusion: We concluded that HDR-BT gave additional benefits for the control of symptoms and general performance and endobronchial obstruction & atelectasis. And HDR-BT will be an additional treatment for the recurrent and endobronchial obstructive lung cancer.

• Food Science and Preservation
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• v.24 no.1
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• pp.21-26
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• 2017

This study was performed to determine the effects of preconditioning process (Con, roasting; SR, steaming and roasting; HDR, hot air drying and roasting; SHDR, steaming hot air drying and roasting) and roasting on the antioxidant and physicochemical properties of acorn (Quercus species) tea. Each sample was extracted in $95^{\circ}C$ hot water for 5 min. The color values of lightness and yellowness were the highest in HDR, and redness were the highest in the control. The total sugar content was the highest in SHDR. Total polyphenol and total flavonoid contents of HDR tea were higher than those of teas prepared by the different processes. DPPH and ABTS radical scavenging abilities of HDR were 75.66% and 98.16%, respectively, which were higher than those of other teas. In the sensory evaluation, HDR tea was ranked significantly higher than other teas in terms of flavor, taste and overall acceptability. Finally, acorn tea treated with drying was superior to other treatments in antioxidant and quality properties. The result suggests that HDR can be applied to acorn tea to achieve better quality and functionality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1054-1064
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• 2012

HDR (high dynamic range) tone mapping algorithms are used in image processing that reduces the dynamic range of an image to be displayed on LDR (low dynamic range) devices properly. The retinex is one of the tone mapping algorithms to provide dynamic range compression, color constancy, and color rendition. It has been developed through multi-scale methods and luminance-based methods. Retinex algorithms still have drawbacks such as the emphasized noise and desaturation. In this paper, we propose a multi scale tone mapping algorithm for enhancement of contrast, saturation, and noise of HDR rendered images based on visual brightness functions. In the proposed algorithm, HSV color space has been used for preserving the hue and saturation of images. And the algorithm includes the estimation of minimum and maximum luminance level and a visual gamma function for the variation of viewing conditions. And subjective and objective evaluations show that proposed algorithm is better than existing algorithms. The proposed algorithm is expected to image quality enhancement in some fields that require a improvement of the dynamic range due to the changes in the viewing condition.

• Broadcasting and Media Magazine
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• v.20 no.4
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• pp.28-37
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• 2015

비디오의 사실감을 극대화하기 위하여 근래에 HDTV에서 지원하는 명암비(dynamic range)와 색역(color gamut)보다 넓은 고명암비(HDR, High Dynamic Range) 및 넓은 광색역(WCG, Wide Color Gamut)을 제공하기 위한 연구가 활발하게 진행되고 있으며, 다양한 표준화가 여러 표준화 단체에서 진행되고 있다. 본 논문에서는 고명암비 및 광색역 비디오 서비스를 위한 다양한 분야의 표준화 동향을 살펴보고자 한다.

• Information Display
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• v.17 no.6
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• pp.17-23
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• 2016

• Korea Information Processing Society Review
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• v.7 no.3
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• pp.26-29
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• 2000