• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3213-3228
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• 2023

As an important part of the digital reactor, the pin-by-pin wise fine coupling calculation is a research hotspot in the field of nuclear engineering in recent years. It provides more precise and realistic simulation results for reactor design, operation and safety evaluation. CORCA-K a nodal code is redeveloped as a robust pin-by-pin wise neutronics and thermal-hydraulic coupled calculation code for pressurized water reactor (PWR) core. The nodal green's function method (NGFM) is used to solve the three-dimensional space-time neutron dynamics equation, and the single-phase single channel model and one-dimensional heat conduction model are used to solve the fluid field and fuel temperature field. The mesh scale of reactor core simulation is raised from the nodal-wise to the pin-wise. It is verified by two benchmarks: NEACRP 3D PWR and PWR MOX/UO₂. The results show that: 1) the pin-by-pin wise coupling calculation system has good accuracy and can accurately simulate the key parameters in steady-state and transient coupling conditions, which is in good agreement with the reference results; 2) Compared with the nodal-wise coupling calculation, the pin-by-pin wise coupling calculation improves the fuel peak temperature, the range of power distribution is expanded, and the lower limit is reduced more.

• 한국전산유체공학회지
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• 제14권4호
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• pp.1-6
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• 2009

In the present study, numerical simulations were performed in a stirred solid/liquid system by using Eulerian multi-phase model. The transient flow field of liquid and distribution of solid particles were predicted in the stirred tank with pitched paddle impeller and baffles. The Frozen rotor method is adopted to consider the rotating motion of the impeller. The effects of number and width of baffles on the mixing time and the quality of solid suspension in the stirred tank are presented numerically. The result shows that the mixing time decreases as the width and number of baffles increase. The present numerical methodology can be applied to optimizing mixing condition of industrial mixer.

• Journal of Power Electronics
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• 제12권6호
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• pp.974-981
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• 2012

A FPGA based delta modulated single phase matrix converter has been developed that may be used in both cyclo-converters and cyclo-inverters. This converter is ideal for variable speed electrical drives, induction heating, fluorescent lighting, ballasts and high frequency power supplies. The peripheral input-output and FPGA interfacing have been developed through Xilinx 9.2i, to generate delta modulated trigger pulses for the converter. The controller has been relieved of the time consuming computational task of PWM signal generation by implementing the method of trigger pulse generation in a FPGA by using Hardware Description Language VHDL in Xilinx. The trigger circuit has been tested qualitatively by observing various waveforms on an oscilloscope. The operation of the proposed system has been found to be satisfactory.

• 대한임베디드공학회논문지
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• 제18권5호
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• pp.209-215
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• 2023

This study proposes an AC servo motor control program structure and its implementation method to efficiently integrate 13 types of additional compensation algorithms into the basic FOC (field-oriented control) algorithm program. Various compensation algorithms are necessary to enhance the stability and performance of machine tools by compensating for interference from disturbances and vibrations. Each compensation algorithm is implemented as a separate, independent function and called from a switch-case statement in the ISR (interrupt service routine) of the PWM (pulse-width modulation) device. The advantages of this approach include facilitating not only debugging and testing but also reducing the possibility of errors during the program development phase. Thus, it is easy to add and activate each specific compensation algorithm for the program update during the program operation phase. The implemented motor control program was experimented with a single-axis feed shaft testbed driven by a commercial AC servo motor control drive board and a 750 Watts SPMSM (surface-mounted permanent magnet synchronous motor), and the results verified its normal operation and performance improvement.

• 토지주택연구
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• 제13권3호
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• pp.115-123
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• 2022

최근 국내에서도 토목분야에 BIM을 활용하는 범위나 빈도가 점점 증가하고 있다. 하지만 전면설계로써 BIM을 적용하는 것이 아닌 2D 설계 이후 BIM 모델링을 수행하는 전환설계로써 BIM을 활용하고 있다. 본래 목적에 맞게 BIM을 활용하기 위해서는 전면설계로써 BIM을 활용해야 하지만, 갑작스러운 변화는 오히려 시장의 혼란과 BIM에 대한 거부감을 높일 수 있기때문에 전환설계로써 BIM 활용을 통해 단계적 BIM 정착을 진행하고 있다. 하지만, 현재 기본 설계단계에서 수행하고 있는 전환설계 방법은 낮은 업무 효율성으로 인해 실제 업무 적용에 많은 어려움이 따르고 있다. 따라서 본 연구에서는 현재 전환설계로써 BIM을 활용하는 기존의 프로세스를 분석하고 기존 프로세스에서 문제점을 보완할 수 있는 기본설계단계에서의 BIM 적용 프로세스를 제안하고자 한다.

• Current Optics and Photonics
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• 제2권2호
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• pp.147-152
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• 2018

We propose a novel bi-focal metallic Fresnel zone plate (MFZP) with shallow depth-of-field (DOF) characteristics. We design the specific annular slit patterns, exploiting the phase-selection-rule method along with the particle swarm optimization algorithm, which we have recently proposed. We numerically investigate the novel characteristics of the bi-focal MFZP in comparison with those of another bi-focal MFZP having equivalent functionality but designed by the conventional multi-zone method. We verify that whilst both bi-focal MFZPs can produce dual focal spots at $15{\mu}m$ and $25{\mu}m$ away from the MFZP plane, the former exhibits characteristics superior to those of the latter from the viewpoint of axial resolution, including the axial side lobe suppression and axial DOF shallowness. We expect the proposed bi-focal MFZP can readily be fabricated with electron-beam evaporation and focused-ion-beam processes and further be exploited for various applications, such as laser micro-machining, optical trapping, biochemical sensing, confocal sensing, etc.

• 한국전산구조공학회논문집
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• 제24권4호
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• pp.463-469
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• 2011

BIM(Building Information Modeling)은 원칙적으로 건설 전 생애주기에 걸쳐 활용되어야 그 효과를 극대화 할 수 있으나, 아직은 계획 및 설계단계에 비하여 공사단계에서는 그 활용도가 상당히 낮은 수준이었다. 최근 대형 국책사업이 발주, 시공되면서 효율적인 공사관리를 위한 방법으로 3D 성과품 검토나 4D 공정관리 등 BIM기법 중 일부가 도입되고 있다. 본 연구에서는 토목시설물의 공사단계에서 BIM 활용방안에 대하여 제시하였다. 토목공사의 종류별, 관리 분야별 BIM 활용방안에 대하여 논의하고, 서울 지하철 919공구에 실제로 적용하여 그 효용성에 대하여 분석하였다. 특히, 현장에 구축된 BIM 기반의 웹 공사관리 시스템은 공사중, 현장과 본사를 비롯해 발주처와 감리단 등 다수의 공사 주체들이 BIM을 보다 효과적으로 사용하도록 함으로써, BIM의 공사단계 활용성을 높일 뿐만 아니라 유지관리 단계까지 확장하여 이용될 수 있다.

• 한국멀티미디어학회논문지
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• 제17권6호
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• pp.751-758
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• 2014

Under the environment of various network and multimedia, various theories are studied to make utilize digital story telling authoring. In the era of digital convergence and ubiquitous information, they want to send information with additional emotional information which is preferred constructive sending method. Digital storytelling refers to a unified technology for narrative structure with the picture and act. If engraft with particular research field, It will make interactive or linear story structure. These structures have problems that they are mismanaging on the result and they are not integrated systemization in each society. Because those are designing storytelling without development process and they are focusing on web distribution. This thesis is design using the object-oriented methodology of component-based design methodology, This thesis create digital storytelling and design metadata for contents management. In the requirement phase, subject and predicate part are extracted from the narrative structure of the story and restructure an organization. We explain by giving specific examples "kongjwi and patjwi" story as a case study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.22-24
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• 1997

The 4-pole LHSM was composed of the figure-of-eight shaped 3-phase armature windings. DC field windings, and the segmented secondary with the transverse bar track. The motor was designed on the base of the performance characteristic equations and the equivalent circuit model, with the coefficients of the magnetic shape. These coefficients were computed from the analytical expressions and examined from FEM analysis. The magnetic equivalent circuit of 3-D model of LHSM was obtained. and this concept provided the equivalent models for 2-D FEM analysis. Therefore, the airgap field, the lift and thrust force were calculated and compared with the results of magnetic equivalent circuit method.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.216-221
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• 2024

Ion cyclotron range of frequency (ICRF) heating system is an important auxiliary heating method in the experimental Advanced Superconducting Tokamak (EAST). In EAST, several megawatts of power are transmitted with coaxial transmission lines and coupled to the plasma. For the long pulse and high power operation of the ICRF waves heating system, it is very important to effectively control the power and initial phase of the ICRF signals. In this paper, a power and phase feedback control system is described based on field programmable gate array (FPGA) devices, which can realize complicated algorithms with the advantages of fast running and high reliability. The transmitted power and antenna phase are measured by a power and phase detector and digitized. The power and phase feedback control algorithms is designed to achieve the target power and antenna phase. The power feedback control system was tested on a dummy load and during plasma experiments. Test results confirm that the feedback control system can precisely control ICRF power and antenna phase and is robust during plasma variations.