• Journal of Environmental Policy
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• v.14 no.3
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• pp.21-40
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• 2015

Heat waves are not new, but due to climate change, the probability of occurrence and severity of heat waves increases, which results in more adverse impacts and damages on local community. Accordingly, the need to tackle heat waves in a more comprehensive and precautionary manner increases. Our study therefore lays emphasis on 1) a long-term plan which not only includes short-term plans in response to the observed damages, but also incorporates relevant sectors to deal with potential impacts in longer term perspective; and 2) a mechanism to manage and adjust the plan in a sustainable manner. In doing so, it examines the impacts of heatwaves and existing plans to tackle them. Based on that, two key conceptual frameworks, namely policy integration and adaptive management, are applied to provide strategies for the development and management of a long-term adapting heatwave plan addressing climate change.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.183-190
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• 2011

As the number of mobile subscribers has increased recently, the demand for more number of base stations has increased. However, because of the shortage of sites for constructing base stations, a mobile communication module needs to be small in size. To minimize the size of the module, the size of the heat sink attached to the outside of the module should be minimized. Furthermore, the temperature of each electronic component of the module should be lower than the allowable temperature so that thermal stability can be maintained. A commercial PIDO (process integration and design optimization) tool PIAnO and a commercial CFD (computational fluid dynamics) tool FLOTHERM are used to minimize the size of the module while the constraints on the temperatures of the twelve electronic components are satisfied. As a result of design optimization, the volume of the heat sink is reduced by 41.9% while all the constraints on the temperature of the twelve electronic components of the module are satisfied.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.60-67
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• 2021

This study presented techno-economic analysis of a 500 MWe oxy-coal power plant with CO2 capture. The power plant included a circulating fluidized-bed (CFB), ultra-supercritical steam turbine, flue gas conditioning (FGC), air separation unit (ASU), and CO2 processing unit (CPU). The dry flue gas recirculation (FGR) was used to control the combustion temperature of CFB. One FGR heat exchanger, one heat exchanger for N2 stream exiting ASU, and a heat recovery from CPU compressor were considered to enhance heat efficiency. The decrease in the temperature difference (ΔT) of the FGR heat exchanger that means the increase in heat recovery from flue gas enhanced the electricity and exergy efficiencies. The annual cost including the FGR heat exchanger and FGC cooling water was minimized at ΔT = 10 ℃, where the electricity efficiency, total capital cost, total production cost, and return on investment were 39%, 1371 M$, 90 M$, and 7%/y, respectively.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.13-26
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• 2006

When the stagnation temperature of a perfect gas increases, the specific heat for constant pressure and ratio of the specefic heats do not remain constant any more and start to vary with this temperature. The gas remains perfect: its state equation remains always valid, with exception that it will be named by calorically imperfect gas. The aim of this research is to develop the relations of the necessary thermodynamics and geometrical ratios. and to study the supersonic flow at high temperature. lower than the threshold of dissociation. The results are found by the resolution of nonlinear algebraic equations and integration of complex analytical functions where the exact calculation is impossible. The dichotomy method is used to solve the nonlinear equation. and the Simpson algorithm for the numerical integration of the found integrals. A condensation of the nodes is used. Since. the functions to be integrated have a high gradient at the extremity of the interval of integration. The comparison is made with the calorifcally perfect gas to determine the error made by this last. The application is made for the air in a supersonic nozzle.

• Electronics and Telecommunications Trends
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• v.38 no.6
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• pp.41-51
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• 2023

Heat dissipation technology for semiconductors and electronic packaging has a substantial impact on performance and lifespan, but efficient heat dissipation is currently facing limited improvement. Owing to the high integration density in electronic packaging, heat dissipation components must become thinner and increase their performance. Therefore, heat dissipation materials are being devised considering conductive heat transfer, carbon-based directional thermal conductivity improvements, functional heat dissipation composite materials with added fillers, and liquid-metal thermal interface materials. Additionally, in heat dissipation structure design, 3D printing-based complex heat dissipation fins, packages that expand the heat dissipation area, chip embedded structures that minimize contact thermal resistance, differential scanning calorimetry structures, and through-silicon-via technologies and their replacement technologies are being actively developed. Regarding dry cooling using single-phase and phase-change heat transfer, technologies for improving the vapor chamber performance and structural diversification are being investigated along with the miniaturization of heat pipes and high-performance capillary wicks. Meanwhile, in wet cooling with high heat flux, technologies for designing and manufacturing miniaturized flow paths, heat dissipating materials within flow paths, increasing heat dissipation area, and reducing pressure drops are being developed. We also analyze the development of direct cooling and immersion cooling technologies, which are gradually expanding to achieve near-junction cooling.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.186-193
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• 2014

A thin Cu seed layer for electroplating has been employed for decades in the miniaturization and integration of printed circuit board (PCB), however many problems are still caused by the thin Cu seed layer, e.g., open circuit faults in PCB, dimple defects, low conductivity, and etc. Here, we studied the effect of heat treatment of the thin Cu seed layer on the deposition rate of electroplated Cu. We investigated the heat-treatment effect on the crystallite size, morphology, electrical properties, and electrodeposition thickness by X-ray diffraction (XRD), atomic force microscope (AFM), four point probe (FPP), and scanning electron microscope (SEM) measurements, respectively. The results showed that post heat treatment of the thin Cu seed layer could improve surface roughness as well as electrical conductivity. Moreover, the deposition rate of electroplated Cu was improved about 148% by heat treatment of the Cu seed layer, indicating that the enhanced electrical conductivity and surface roughness accelerated the formation of Cu nuclei during electroplating. We also confirmed that the electrodeposition rate in the via filling process was also accelerated by heat-treating the Cu seed layer.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.209-214
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• 1998

A thermodynamic simulation method is developed for the process design and the performance evaluation of the gas turbine in IGCC power plant. The present study adopts four clean coal gases derived from four different coal gasification and gas clean-up processes as IGCC gas turbine fuel, and considers the integration design condition of the gas turbine with ASU(Air Separation Unit). In addition, the present simulation method includes compressor performance map and expander choking models for considering the off-design effects due to coal gas firing and ASU integration. The present prediction results show that the efficiency and the net power of the IGCC gas turbines are seperior to those of the natural gas fired one but they are decreased with the air extraction from gas turbine to ASU. The operation point of the IGCC gas turbine compressor is shifted to the higher pressure ratio condition far from the design point by reducing the air extraction ratio. The exhaust gas of the IGCC gas turbine has more abundant wast heat for the heat recovery steam generator than that of the natural gas fired gas turbine.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.957-966
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• 2023

In this paper, we propose a new real-time adaptive PID temperature control technique. This is a technique that prevents overshoot by introducing a model that represents the control object. To prevent excessive integration that causes overshoot, integral control adjusts the integral gain to track the heat loss of the model in real time. In the conventional PID control, the integration was dependent on proportional control and the gain was fixed to a constant. As a result, applying two gains that mismatch each other could cause excessive overshoot. However, the proposed adaptive control actively eliminates overshoot so that the integral control amount does not always exceed the heat loss. The cause of overshoot in PID control is integration. Basically, proportional control does not cause overshoot. Therefore, according to the proposed technique, adaptive PID control without the need for tuning experiments can be realized.

• ETRI Journal
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• v.27 no.3
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• pp.337-340
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• 2005

A spot-size converted Fabry-Perot laser diode (LD) was flip-chip bonded to a silica-terraced planar lightwave circuit(PLC) platform to examine the effect of the silica terrace on the heat dissipation of the LD module. From the measurement of the light-current characteristics, it was discovered that the silica terrace itself is not a strong thermal barrier, but the encapsulation of the integrated LD with an index-matching polymer resin more or less deteriorates the heat dissipation.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.3
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• pp.296-301
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• 2012

This paper describes an analytic method for infrared thermography to detect surface cracks in thin plates. Traditional thermographic method uses the spatial contrast of a thermal field, which is often corrupted by noise in the experiment induced mainly by emissivity variations of target surfaces. This study developed a robust analytic approach to crack detection for thermography using the holomorphic function of a temperature field in thin plate under steady-state thermal conditions. The holomorphic function of a simple temperature field was derived for 2-D heat flow in the plate from Cauchy-Riemann conditions, and applied to define a contour integral that varies depending on the existence and strength of singularity in the domain of integration. It was found that the contour integral at each point of thermal image reduced the noise and temperature variation due to heat conduction, so that it provided a clearer image of the singularity such as cracks.