• JSTS:Journal of Semiconductor Technology and Science
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• 제16권3호
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• pp.367-374
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• 2016

This paper presents an electro-thermal modeling of an amorphous silicon (a-Si) uncooled microbolometer. This modeling provides a comprehensive solution for simulating the electro-thermal characteristics of the fabricated microbolometer and enables electro-thermal co-simulation between MEMS and CMOS integrated circuits. To validate this model, three types of uncooled microbolometers were fabricated using a post-CMOS surface micromachining process. The simulation results show a maximum discrepancy of 2.6% relative to the experimental results.

• Current Optics and Photonics
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• 제3권5호
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• pp.445-450
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• 2019

The influence of high-power laser diode (HPLD) emitter width on the device performance is investigated for 975-nm (In,Ga)(As,P)/(Al,Ga)As broad-area HPLDs, using self-consistent electro-thermal-optical simulation. To guarantee the simulation's accuracy, simulated results are matched with the measured results for a sample HPLD with fitting parameters. The influences of HPLD emitter width on temperature distribution, output power, and the beam product parameter (BPP) are analyzed for three different emitter widths of 50, 70, and $90{\mu}m$. It is found that a device with smaller emitter width exhibits both thermal rollover and thermal blooming at lower output power, but smaller BPP.

• 조명전기설비학회논문지
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• 제28권1호
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• pp.9-15
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• 2014

This paper focuses on the heat gain of a lighting system, one of the most-used appliances in buildings, and its thermal effect within a low energy building. In this study, a dynamic thermal model of a lighting system is first established based on the first principle of thermodynamics. Then, thermal parameters of this model are estimated by experiments and an optimization process. Afterward, the obtained model of the system is validated by comparing simulation results to experimental one. Finally it is integrated into a low energy building model in order to quantify its thermal influence within a low energy building. As a result, heat flux of the lighting system, indoor temperature and heating energy demands of the building are obtained and compared with the results obtained by the conventional model of a lighting system. This paper helps to understand thermal dynamics of a lighting system and to further apply lighting systems for energy management of low energy buildings.

• 한국태양에너지학회 논문집
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• 제38권5호
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• pp.37-47
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• 2018

The heating performance of a solar thermal seasonal storage system applied to a glass greenhouse was analyzed numerically. For this study, the gardening 16th zucchini greenhouse of Jeollanam-do agricultural research & extension services was selected. And, the heating load of the glass greenhouse selected was 576 GJ. BTES (Borehole Thermal Energy Storage) was considered as a seasonal storage, which is relatively economical. The TRNSYS was used to predict and analyze the dynamic performance of the solar thermal system. Numerical simulation was performed by modeling the solar thermal seasonal storage system consisting of flat plate solar collector, BTES system, short-term storage tank, boiler, heat exchanger, pump, controller. As a result of the analysis, the energy of 928 GJ from the flat plate solar collector was stored into BTES system and 393 GJ of energy from BTES system was extracted during heating period, so that it was confirmed that the thermal efficiency of BTES system was 42% in 5th year. Also since the heat supplied from the auxiliary boiler was 87 GJ in 5th year, the total annual heating demand was confirmed to be mostly satisfied by the proposed system.

• 한국지열·수열에너지학회논문집
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• 제17권2호
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• Applied Microscopy
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• 제25권2호
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• pp.73-79
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• 1995

The oxidation of silicon wafers is an essential step in the fabrication of semiconductor devices. It is known to induce degradation of electrical properties and lattice strain of Si substrate from thermal oxidation process due to charged interface and thermal expansion mismatch from thermally grown SiO, film. In this study, convergent beam electron diffraction technique is employed to directly measure the lattice strains in Si(100) and $4^{\circ}$ - off Si(100) substrates with thermally grown oxide layer at $1200^{\circ}C$ for three hours. The ratios of {773}-{973}/{773}-{953} Higher Order Laue Zone lines were used at [012] zone axis orientation. Lattice parameters of the Si substrate as a function of distance from the interface were determined from the computer simulation of diffraction patterns. Correction value for the accelerating voltage was 0.2kV for the kinematic simulation of the [012]. HOLZ patterns. The change in the lattice strain profile before and after removal of oxide films revealed the magnitudes of intrinsic strain and thermal strain components. It was shown that $4^{\circ}$ -off Si(100) had much lower intrinsic strain as surface steps provide effective sinks for the free Si atoms produced during thermal oxidation. Thermal strain in the Si substrate was in compression very close to the interface and high concentration of Si interstitials appeared to modify the thermal expansion coefficient of Si.

• 토지주택연구
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• 제1권1호
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• pp.19-25
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• 2010

최근 에너지 절약을 화두로 건물에서의 에너지 절약기술들이 크게 요구되어 지는 반면 재실자의 온열쾌적환경은 비교적 비중 있게 다루어지지 않고 있다. 실내공간의 쾌적성은 재실자의 만족감과 더불어 생산성을 향상시키는 등의 역할을 하며, 최근 삶의 질 향상 등에 따라 그 필요성이 크게 요구되고 있는 실정이다. 따라서 본 연구에서는 공동주택을 대상으로 겨울철 난방 시 쾌적지표를 통한 실내 온열환경 제어의 타당성을 검토하고자 시뮬레이션을 수행하였으며, 주거건물에서의 일상적인 실내온도와 에너지 절약 설계기준에서 제시한 실내 설정온도, 그리고 쾌적지표를 설정으로 한 각 제어조건의 온열환경과 에너지 소비량을 비교 분석 및 검토하였다. 본 연구결과에 따르면, 쾌적지표인 PMV로 실내환경을 제어했을 때 에너지 절약설계 기준인 $22^{\circ}C$로 실내온도를 설정하였을 때보다 에너지 소비량은 29% 증가하지만 주거용 건물에서 일반적으로 유지되는 실내온도인 $24^{\circ}C$ 보다는 에너지소비량은 11% 정도 감소하며, 온열쾌적감도 각 제어조건 중 가장 우수하게 나타났다. 따라서 여러 가지 제어변수들을 통한 연구가 지속된다면 주거용 건물에서도 쾌적지표를 활용한 실내 공간의 제어방법은 건물의 에너지를 절약하고 실내 환경의 쾌적성을 증대시키는 주요기술이 될 수 있을 것으로 기대된다.

• 설비공학논문집
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• 제22권12호
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• pp.873-880
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• 2010

The present study developed a computer simulation program to determine the optimum strategy and capacity of a micro combined heat and power(CHP) system. This simulation program considered a part-load electrical/thermal efficiency and transient response characteristics of CHP unit. The result obtained from the simulation was compared with the actual operation of 30 kW gas engine driven micro CHP system. It was found that the simulation could reproduce the daily operation behavior, such as operating hours and mean load factor, closely to the actual behavior of the system and could predict the amount of electrical/thermal output and fuel consumption with the error of less than 12%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.656-661
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• 2000

In the recent trend of electric power supply market, a variable pressure operation supercritical once-through steam generator is highlighted as a thermal power plant for cycling load because of its superiority in load regulation. Almost all thermal power plants of the future are expected to be variable pressure operation supercritical once-through units. APESS(Advanced Plant Engineering & Simulation System) is a dynamic simulation software for power plant which is under being developed by Korea Heavy Industries & Construction Co., Ltd. This paper present the introduction of APESS and the result of simulation for variable pressure operation supercritical once-through steam generator.

• 한국태양에너지학회 논문집
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• 제32권1호
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• pp.40-47
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• 2012

According to the advancement of computer and simulation method, it becomes possible to predict indoor climate precisely by using CFD simulation coupled with heat conduction, convection, and radiation. However, predicting the indoor climate is generally conducted by using a simplified CFD coupled simulation method since it takes quite long time to use a general CFD simulation method. In this study, a simplified CFD coupled simulation was conducted in order to find out the effect of natural ventilation by wind-driven in atrium. As a result of calculation, it was clarified that the natural ventilation driven by temperature difference was not enough to remove the accumulated heat of upper zone and the natural ventilation by wind-driven was needed. Finally, it is required to decide the window direction and size based on correct indoor climate prediction method for the effective use of natural ventilation by wind-driven.