• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.549-552
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• 2009

Methane hydrate is crystalline ice-like compounds which formed methane gas enters within water molecules composed cavity at specially temperature and pressure condition, and water molecule and each other from physically-bond. $1m^3$ hydrate of pure methane can be decomposed to the maximum of $172m^3$ at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18~24% less than the liquefied transportation. However, when methane hydrate is formed artificially, the amount of consumed gas is relatively low due to a slow reaction rate between water and methane gas. In this study, for the better hydrate reaction rate, there is make nano fluid using ultrasonic dispersion of carbon nano tube. and then, Experiment with hydrate formation by nano fluid and methane gas reaction. The results show that when the carbon nano tubes of 0.004 wt% was added to pure water, the amount of consumed gas was about 300% higher than that in pure water and the hydrate formation time decreased.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.607-615
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• 2022

In this study, economic analysis program was developed for economic evaluation of hydrogen production, storage/delivery, and utilization technologies as well as overseas import of hydrogen. Economic analysis program can be used for the estimation of the levelized cost of hydrogen for hydrogen supply chain technologies. This program include five hydrogen production technology on steam methane reforming and water electrolysis, two hydrogen storage technologies (high compressed gas and liquid hydrogen storage), three hydrogen delivery technologies (compressed gas delivery using tube trailer, liquid hydrogen, and pipeline transportation) and six hydrogen utilization technologies on hydrogen refueling station and stationary fuel cell system. In the case of overseas import hydrogen, it was considered to be imported from five countries (Austraila, Chile, India, Morocco, and UAE), and the transportation methods was based on liquid hydrogen, ammonia, and liquid organic hydrogen carrier. Economic analysis program that was developed in this study can be expected to utilize for planning a detailed implementation methods and hydrogen supply strategies for the hydrogen economy road map of government.

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.215-226
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• 2024

This study presents an experimental investigation into the performance of self-sensing grout formulated with a high volume of ultra-fine fly ash(UHFA). To explore the potential benefits of alternative cementitious materials, the research examined the effect of substituting UHFA with equal parts of blast furnace slag(BFS) fine powder. Both UHFA and BFS are byproducts generated in significant quantities by industrial processes. The evaluation focused on the fresh properties of the grout, including its flow characteristics, as well as the hardened properties such as compressive strength, dimensional stability(length change rate), and electrical properties. The experimental results demonstrated that incorporating UHFA resulted in a substantial reduction in the plastic viscosity of the grout, translating to improved flowability. Additionally, the compressive strength of the UHFA-modified grout surpassed that of the reference grout(without UHFA substitution) at all curing ages investigated. Interestingly, the electrical characteristics, as indicated by the relationships between FCR-stress and FCR-strain, exhibited similar trends for both grout mixtures.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.260-263
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• 2007

The importance of natural light in building is known by all of us who experienced dark rooms. The sunlight system is very important from energy saving and human welfare point of view. The system consists of light-collecting module, light -transporting module and light-emitting module. The light-collection is used light reflection mirror, a prism for lighting bent, and lens for light condensing. The transportation of collected sunlight is used polished duct, tube, pipe and specially used fiber optic cable. This paper investigate research and development trends of sunlight system for advanced product.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.694-698
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• 2004

The importance of insulating material becomes greater recently in order to attain a quieter life style amidst today's sound noise such as transportation, industrial machinery. The demand for insulating material is increasing due to the increase of noise space. It is reasonable to predict the transmission loss and the absorption of the insulating Material before arranging it in the appropriate places and attaining a Pleasant acoustic environment inside the space. The experiments of insulating material's were performed using Impedance tube Type 4206 T of B&K, and VIOLINS which is a FEM Program of LMS was used for the analysis

• Journal of computational fluids engineering
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• v.18 no.4
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• pp.53-60
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• 2013

The boron transport model has been implemented into the CUPID code to simulate the boron transport phenomena of the PWR. The boron concentration conservation was confirmed through a simulation of a conceptual boron transport problem in which water with a constant inlet boron concentration injected into an inlet of the 2-dimensional vertical flow tube. The step wise boron transport problem showed that the numerical diffusion of the boron concentration can be reduced by the second order convection scheme. In order to assess the adaptability of the developed boron transport model to the realistic situation, the ROCOM test was simulated by using the CUPID implemented with the boron transportation.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.50-51
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• 2017

최근 전 세계적으로 차세대 초고속 교통수단의 연구, 개발에 박차를 가하고 있다. 대표적으로 미국에서 개발하고 있는 하이퍼루프는 승객을 태운 차체가 원통형인 튜브안에서 최대 1200 km/h로 이동하는 초고속 교통수단이다. 이렇게 빠른 속도에 도달하기 위해서 수십 MW 수준의 상당히 큰 전력이 필요하며, 이러한 큰 전력소모에 의한 전력망의 부담을 덜기 위해, 태양광 시스템을 튜브에 장착하여 추진에 필요한 일부 전력을 태양광 발전으로 대체하는 시스템이 연구되고 있다. 본 논문에서는 튜브의 방향, 태양전지의 배열에 따른 에너지 생산량, 전력발전량 및 비용 등의 다각적인 측면에서의 분석을 제시하였다. 원통형 튜브에 부착되는 태양전의 배열을 여섯 가지 경우로 나누었을 때, 삼각 지붕 모양으로 태양전지를 배열한 Case 2가 가장 높은 에너지 생산량을 보였다. 하지만 태양전지의 단위면적 당 에너지 생산량을 비용으로 계산하였을 경우, 튜브 위에 평평하게 태양전지를 배열한 Case 1이 가장 높은 가격 경쟁력을 가졌다.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.42-48
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• 2012

Hydroforming has attracted the attention of manufacturing industries for vehicles and transportation systems. A wide range of products such as subframes, camshafts, radiator frames, axles and crankshafts are made by the hydroforming process. Hydroformed parts often need to be structurally joined to other components during assembly. Therefore it is useful if the hydroformed automotive parts can be attached with a localized flange. In this study, a hydroforming process to produce a rectangular shape flange is proposed. FE analysis to form the flanged rectangular shape was performed by Dynaform 5.5. The hydroforming characteristics at various die aspect ratios and feeding conditions were analyzed and optimal process conditions which can avoid defects are suggested. For validation purposes, hydroforming experiments to form the flange were conducted with the optimized conditions. The results show that the flanged parts can be successfully formed with a hydroforming process without additional processing steps.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.8
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• pp.366-374
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• 2014

Experimental mass transfer data, which were obtained for the $CO_2$-water slug flows in vertical tubes with 2, 5, and 8mm diameters, were analyzed in comparison with the penetration theory. It was found that a penetration model with molecular diffusion coefficient cannot predict the experimental data accurately. An effective diffusion coefficient, which considers enhancement effect of interfacial waves, was suggested to improve prediction. Another empirical factor was also suggested to consider the effect of non-uniform interface velocity. A modified penetration model was found to be capable of predicting the experimental data reasonably well.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.111-115
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• 2006

To clarify the hydraulic and thermal characteristics of ice slurry which made from 6.5% ethylene glycol-water solution flow in the double tube and plate type heat exchanger, experimental studies were performed. The mass flux and Ice fraction of ice slurry were varied from 800 to $3,500 kg/m^2s$(or 7 to 17 kg/min) and from 0 to 25%, respectively. During the experiment, it was found that the measured pressure drop and heat transfer rate increase with the mass flux and ice fraction; however the effect of ice fraction appears not to be significant at high mass flux region. At the region of low mass flux, a sharp increase in the pressure drop and heat transfer rate were observed depends on mass flux.