• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1253-1260
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• 2022

This paper reports the control method for the core power of the China initiative Accelerator Driven System (CiADS) facility. In the CiADS facility, an intense external neutron source provided by a proton accelerator coupled to a spallation target is used to drive a sub-critical reactor. Without any control rod inside the sub-critical reactor, the core power is controlled by adjusting the proton beam intensity. In order to continuously change the beam intensity, an adjustable aperture is considered to be used at the Low Energy Beam Transport (LEBT) line of the accelerator. The aperture size is adjusted based on the Proportional Integral Derivative (PID) controllers, by comparing either the setting beam intensity or the setting core power with the measured value. To evaluate the proposed control method, a CiADS core model is built based on the point reactor kinetics model with six delayed neutron groups. The simulations based on the CiADS core model have indicated that the core power can be controlled stably by adjusting the aperture size. The response time in the adjustment of the core power depends mainly on the adjustment time of the beam intensity.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2656-2661
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• 2023

The project of China initiative Accelerator Driven Subcritical (CiADS) system has been started to construct in southeast China's Guangdong province since 2019, which is expected to be checked and accepted in the year 2025. In order to make the students in University of Chinese Academy of Sciences (UCAS) better understand the main characteristic and the operation condition in the subcritical nuclear facility, the training platform for CiADS has been developed based on the Cave Automatic Virtual Environment (CAVE) in the Institute of Modern Physics Chinese Academy of Sciences (IMPCAS). The CAVE platform is a kind of non-head mounted virtual reality display system, which can provide the immersive experience and the alternative training platform to substitute the dangerous operation experiments with strong radioactivity. In this paper, the CAVE platform for the training scenarios in CiADS system has been presented with real-time simulation feature, where the required devices to generate the auditory and visual senses with the interactive mode have been detailed. Moreover, the three dimensional modeling database has been created for the different operation conditions, which can bring more freedom for the teachers to generate the appropriate training courses for the students. All the user-friendly features will offer a deep realistic impression to the students for the purpose of getting the required knowledge and experience without the large costs in the traditional experimental nuclear reactor.

• 보건의료산업학회지
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• 제12권4호
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• pp.191-202
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• 2018

Objectives: The purpose of this study was to identify the factors influencing factors university students' will toward brain death organ donation. Methods: Data from 250 students were collected using a structured questionnaire. The data were analyzed using a chi-squared test, independent t-test, and binary logistic regression with the SPSS 23.0 program. Results: Factors influencing will of brain death organ donation were announcing to decision to engage in brain death donation(Confidence interval(CI)=3.02-32.14, p<.001), experience of having discussed brain death organ donation with others(CI=1.26-5.72, p=.011), intention to make advance directives(ADs)(CI=1.90-9.57., p<.001), and positive attitude toward ADs(CI=1.05-1.29, p=.004). Conclusions: The most important factors affecting the will of brain death organ donation were making an informed decision regarding organ donation, intending to make an AD, having engaged in organ donation conversation, and a positive attitude toward ADs.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.452-459
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• 2023

The core power control is an important issue for the study of dynamic characteristics in China initiative accelerator driven subcritical system (CiADS), which has direct impact on the control strategy and safety analysis process. The CiADS is an experimental facility that is only controlled by the proton beam intensity without considering the control rods in the current engineering design stage. In order to get the optimized operation scheme with the stable and reliable features, the variation of beam intensity using the continuous and periodic control approaches has been adopted, and the change of collimator and the adjusting of duty ratio have been proposed in the power control process. Considering the neutronics and the thermal-hydraulics characteristics in CiADS, the physical model for the core power control has been established by means of the point reactor kinetics method and the lumped parameter method. Moreover, the multi-inputs single-output (MISO) logical structure for the power control process has been constructed using proportional integral derivative (PID) controller, and the meta-heuristic algorithm has been employed to obtain the global optimized parameters for the stable running mode without producing large perturbations. Finally, the verification and validation of the control method have been tested based on the reference scenarios in considering the disturbances of spallation neutron source and inlet temperature respectively, where all the numerical results reveal that the optimization method has satisfactory performance in the CiADS core power control scenarios.

• 방송공학회논문지
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• 제22권4호
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• pp.462-472
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• 2017

네트워크 기술이 발달함에 따라, 한류 등 특정 나라의 미디어 콘텐츠가 해당 나라뿐 아니라 세계적으로 소비되고 있다. 이와 같이, 동일한 콘텐츠가 다양한 국가의 방송환경에서 소비되는 경우, 방송되는 국가 및 지역적 환경 등에 적합한 중간 광고의 삽입 및 대체방안이 필요할 것으로 보인다. 이에 본 논문에서는 ATSC 3.0에서 차세대 방송표준으로 채택한 MMT를 기반으로 하여 하이브리드 방송 환경에서의 중간 광고 삽입 방안을 제안하였다. 제안한 방안은 MMT의 MPT message 및 MMT-CI를 이용하여 시그널링을 전달하고, 이에 따라 광고 데이터를 전송하는 방식으로 중간 광고를 삽입하는 것이다. 이를 검증하기 위해 본 논문에서는 MMT의 구조를 분석하고, 제안한 방안 검증 시스템을 설계하여 실험결과를 통해 제안한 중간 광고 삽입 방안을 검증하였다.

• 전자공학회논문지CI
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• 제44권6호
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• pp.30-35
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• 2007

H.264/AVC 표준은 복호된 영상의 블록간 경계면에서 발생하는 왜곡 및 불연속성을 보정하기 위하여 디블록킹 필터를 사용하여 더 나은 품질을 제공하였다. 하지만 이 과정에서 수많은 메모리 참조연산이 불가피하였으며, 이로 인해 전체 복호기의 처리 시간을 지연시키는 결과를 초래하였다. 본 논문에서는 이러한 디블록킹 필터의 처리 속도를 높이기 위한 자료 재사용 알고리즘을 제안한다. 자료 재사용을 위하여, 새로운 필터링 순서를 제안하여 메모리 참조를 감소시키고 디블록킹 필터의 처리 속도를 높인다. 제안된 알고리즘을 모델링하여 ARM ADS1.2에서 컴파일하고 ARM966E-S프로세서 시스템을 Armulator를 이용하여 시뮬레이션 하였다. 실험 결과, H.264/AVC 표준보다 매크로블록 당 실행 사이클, 메모리 참조 사이클에서 각각 58.45%, 57.93%의 성능 향상을 보였다.

• 전자공학회논문지CI
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• 제38권6호
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• pp.82-92
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• 2001

본 논문은 셀룰러 폰, PDA, 노트북 등과 같은 휴대 단말 시스템에서 내장형으로 사용될 수 있는 32비트 RISC 코어 구현에 대해서 기술하였다. RISC 코어는 ARM$\circled$V4 명령어 셋을 따르며 전형적인 5단 파이프 라인으로 동작한다. 또한 보다 향상된 코드 밀도를 위해 Thumb 코드를 지원하고, 파이프라인 레지스터의 동적 전력 관리 기법을 사용한다. RTL 수준에서 VHDL로 모델링된 코어는 ADS의 ARMulator와 비교 검증되었으며 평균 CPI는 1.44이다. 검증이 완료된 코어는 $0.6{\mu}m$ CMOS 1-poly 3-metal 셀라이브러리를 사용하여 합성 및 레이아웃되었으며 크기는 약 41,000 게이트이고, 예상 동작주파수는 45 MHz이다.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4310-4321
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• 2022

The concept of dense granular-flow target (DGT) for the China Initiative Accelerator Driven Subcritical system (CiADS) is an attractive choice for high heat removal ability, low chemical toxicity, and radiotoxicity. A wobbling hollow beam is proposed to enhance the homogeneity of temperature rise of flowing particles in beam-target coupling zone. In this paper, the design procedure of target and beam parameters was discussed firstly. Then we simulated the heat deposition and transfer of the scanning beam in DGT to study the effect of beam parameters. The results show the flux density of proton beam plays a crucial role in the distribution of temperature rise while the contributions from scanning frequency heat transfer are also obvious. Moreover, heat transfer in transversal directions is insignificant, resulting in a low heat flux towards the sidewalls of DGT. This work not only contributes to the design of DGT, but also beneficial for understanding the beam-target coupling in porous materials.

• 전자공학회논문지CI
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• 제45권2호
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• pp.26-32
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• 2008

동영상 압축 기술은 오랜 기간 동안 연구되었으며 H.264/AVC는 최근에 사용되고 있는 동영상 압축 표준 중 가장 효율적인 동영상 압축 표준으로 알려져 있다. H.264/AVC의 베이스 프로파일에서는 무손실 압축과정으로 기존의 VLC(Variable Length Coding) 방식 대신에 압축 효율을 향상시킨 CAVLC(Context-Adaptive Variable Length Coding)라는 압축 방식을 사용한다. CAVLC 복호기는 기존의 VLC 보다 많은 VLC 표가 필요하기 때문에 하드웨어로 구현하기에는 많은 면적을 요구하게 되며 소프트웨어로 구현 시에는 표 탐색에 의해서 성능이 저하된다. 본 논문에서는 이러한 CAVLC 복호기의 소프트웨어에서의 성능 저하를 막기 위해서 VLC 표를 계층적으로 집단화하여 코드만으로 주소를 정하고 정해진 VLC 표를 한번만 참조하여 성능을 향상시키는 방법을 제안한다. 제안된 알고리즘은 C 언어로 모델링하였으며 ARM ADS1.2에서 컴파일하고 ARM9TDMI 프로세서 시스템을 Armulator를 이용하여 시뮬레이션하였다. 실험 결과, H.264/AVC 표준 참조 프로그램인 JM(Joint Model) 10.2 보다 약 80%의 수행 시간 단축을 보였으며 최근 논문에서의 산술연산 알고리즘보다 15%의 성능 향상을 보였다.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1964-1969
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• 2021

We developed a Dual-PPACs detector for fast neutron measurements that consists of two sets of PPAC: conventional PPAC and fission PPAC. A²³⁸U(U₃O₈) coating is placed in the fission PPAC's anode, which is used as the neutrons conversion layer. An experiment was performed to measure neutron time-of-flight (TOF) in which ²⁵²Cf spontaneous fission source was used. An excellent time resolution of 164ps has been observed at 6 mbar in isobutene gas. With the excellent time resolution of Dual-PPACs detector, exact neutron energy can be extracted from the timing measurement. The experimental detection efficiency was 1.9 × 10^-7, consistent with the efficiency of 2.5 × 10^-7 given by a Geant4 simulation. Ultimately, the results show that the Dual-PPACs detector is a suitable candidate for measuring fast neutrons in the future CiADS system.