• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.660-667
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• 2020

This study focused on the epoxy resin production process, which uses the steam of 155 ℃ or higher as a heat source, and discards all condensate generated. A part of the process is operated at low temperatures of 70 ℃ or below, thus there are opportunities to reduce the steam consumption by recycling wasted condensate as a heat source for the low temperature section of process. In this study, we developed process models that can reduce steam by recovering waste heat through recycling condensate and conducted a case study to find an optimal condensate recycling system. Three different process designs were proposed and economic evaluations were performed by comparing annual capital costs and steam savings in each case. Finally, an annual steam consumption of the low-temperature section could be reduced by up to 67.6%, which could also bring an additional economic benefit of 522.1 million won/yr.

• Environmental and Resource Economics Review
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• v.32 no.3
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• pp.191-215
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• 2023

This study focuses on evaluating and comparing residents' acceptance of unutilized heat such as hydrothermal energy and waste heat from waste incineration and data centers in the case that they are used as district heat sources. This is because securing residents' acceptance is significantly important in order for unutilized heat to be considered as a heat source of district heating and cooling to achieve neutrality in the heating and cooling sector. A survey of heating consumers' perception on unutilized heat energy is conducted and a conjoint model is used to analyze the willingness to pay of heating consumers on incineration heat, water heat, and data center waste heat and to compare them with existing gas heat sources. As a result of the analysis, it is confirmed that district heating using hydrothermal energy and data center waste heat is preferred to district heating from heat from a natural gas plant or waste incineration.

• Tunnel and Underground Space
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• v.34 no.2
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• pp.127-142
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• 2024

The robustness of a numerical method means that its computational performance is maintained under various modeling conditions. New numerical methods or codes need to be assessed for robustness through benchmark testing. The TOUGH-FLAC modeling approach has been applied to various fields such as subsurface carbon dioxide storage, geological disposal of spent nuclear fuel, and geothermal development both domestically and internationally, and the modeling validity has been examined by comparing the results with experimental measurements and other numerical codes. In the present study, a benchmark test of the TOUGH-FLAC approach was performed based on a coupled thermal-hydro-mechanical behavior problem with an analytical solution. The analytical solution is related to the temperature, pore water pressure, and mechanical behavior of a fully saturated porous medium that is subjected to a point heat source. The robustness of the TOUGH-FLAC approach was evaluated by comparing the analytical solution with the results of numerical simulation. Additionally, the effects of thermal-hydro-mechanical coupling terms, fluid phase change, and timestep on the computation of coupled behavior were investigated.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1529-1531
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• 1999

The main functions of AC railroad vehicles arresters is to protect the main transformer from lightening impulse or switching impulse surge, then the MOV(metal oxide varistor) elements rated of 10kA is applied. The residual voltage and surge energy absorption are important parameters in designing arrester, these must be carefully decided with considering protecting level of impulse environment of system. The purpose of this study is to discuss the residual voltages and the energy absorption capability by impulse currents on MOV elements for railroad vehicles, and to introduce design factors which act as optimal protecting condition against impulse currents.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.75-83
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• 2003

Diode laser absorption system is advantageous of their non-invasive nature, fast response time, high sensitivity and real-time measurement capability. Furthermore, recent advances in room-temperature, near-IR and visible diode laser sources for telecommunication, optical data storage applications are enabling combustion diagnostics system based on diode laser absorption spectroscopy. So, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor system are now appearing for a variety of applications. The objective of this research is to take advantage of distributed feed-back diode laser and develope new gas sensing system. It experimentally found out that the wavelength, power characteristics as a function of injection current and temperature. In addition to direct absorption and wavelength modulation spectroscopy have been demonstrated in these experiments and have a bright prospect to this diode laser system.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1964-1968
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• 2007

The river water heat source heat pump has the advantage in the performance compared to air source heat pump. Although its better performance, the large temperature difference between load and source makes system performance worse by nature. In this study, 2-stage compression is considered as the solution of this problem. Generally, heat pump is designed for maximum capacity rate, but it actually operates at part load condition in many cases. Therefore, an information on the part-load character is very important in view of the system overall performance. In this study, part-load performance tests of a R134a 2-stage compression heat pump were carried out over the river water and supply heating water temperature changes. The experimental results show that the system performance is influenced by the part load rates, river water temperature, load temperature, etc.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.97-103
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• 2006

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. On-line data acquisition and processing can be performed with a PC running LabVIEW software, and absorption signals are measured simultaneously by multiplexing method. Finally, It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.53-59
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• 2006

This study is measurement of radicals in gas & light oil diffusion flame focused on burner exit. The goal of this study is to analyse the relationship between flame chemiluminescence($OH^{\ast}$, $CH^{\ast}$, $C_2^{\ast}$) intensities and flame conditions. The investigation performed turbulent diffusion flame of commercial burner in varying the excess air ratio from 1.0 to 1.8. The optical emissions were measured by photomultiplier(PMT) using optical band pass filter and spectrometer system. The effects of excess air ratio and NOx emission characteristics on the radical emission intensities were investigated experimentally.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.15-20
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• 2004

To the development on reusing method of the heat-source waste at Daegu Bisan dyeing-complex, this study is aimed to application of it's crushing material (hereafter waste sand) as concrete fine aggregate. The results are as follows; 1. Flow and unit weight of mortar using waste sand as concrete fine aggregate are decreased. 2. At the results of compressive strength test and bending strength test, mortar using waste sand superior to plain mortar within 80％ substitute ratio of waste sand. Because increasing rate of compressive strength is similar through increasing age, waste sand performs as filler's function of no-effect with cement only. 3. At the results of concrete application test, unit weight of concrete using waste sand is similar to plain concrete and compressive strength of concrete is superior to plain likewise the results of mortar test

• Korean Journal of Materials Research
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• v.6 no.2
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• pp.204-209
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• 1996

각종 전자부품에 이용되는 백금막의 밀착력과 응집화 현상에 대해 연구하였다. 온도저항계수(TCR)의 열화 없이 밀착력을 향상 시키기 위해서 AI, Si의 산화물을 adhesion promoting layer로 이용한 결과 매우 우수한 밀착력과 TCR을 보였다. 질소분위기 600-90$0^{\circ}C$의 온도범위에서 행한 열처리를 통해 응집화현상을 관찰한 결과 응집화는 기판거칠기에 따라 다른 양상을 보였다. Si3N4등의 기판거칠기가 작은 adhesion promoting layer를 이용한 시편의 경우 고온인 90$0^{\circ}C$에서 응집화 현상이 발생되었다. 표면거칠기가 큰 AI-Si 산화물을 adhesion promoting layer로 이용한 시편의 경우 비교적 저온인 $600^{\circ}C$에서 응집화 현상이 발생했으며 80$0^{\circ}C$이상의 열처리의 경우 중앙응집체와 응집체고갈지역이 형성되는 현상을 나타내었다.