• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.227-234
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• 2016

In this study, asphalt paving filler, which satisfies the KS standards, were prepared from industrial by-products, such as fly ash generated from thermal power plants, cogeneration ash generated from cogeneration plants, and desulfurized gypsum generated from the flue-gas desulfurization process. The properties of the prepared mixed filler and the existing limestone filler were compared through laboratory tests for preparing asphalt mixture using each filler. In addition, asphalt pavement field tests were conducted using the limestone filler and mixed filler. The dynamic stability, Marshall stability, tensile strength ratio, saturation, porosity, and flow value of the asphalt mixtures used in the field test were evaluated, as was done in the laboratory test. The laboratory and field construction test results revealed outstanding tensile strength ratio, Marshall stability and dynamic stability when using the prepared filler than for the existing limestone filler. Through optimization of the mixing design, the possibility of developing fillers, which the characteristics of the existing limestone filler, was confirmed.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.149-154
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• 2012

The adsorption and desorption behavior of biofilter-medium was investigated on the performance of an adsorption column. Continuous flow-isothermal adsorption experiments were performed to treat waste air containing such a VOC as ethanol under the same condition of > 90% relative humidity as the condition of the feed to a biofilter process. In case of feeding waste air containing ethanol of 1,000 ppmv (or 2,050 mg ethanol/$m^3$) to the adsorption system at the rate of 2 L/min, the onsets of its breakthrough and reaching the state of dynamic equilibrium at the exit had been delayed 10 and 3 times, respectively, later than those at the 1st stage sampling port. Moreover, in case of 2,000 ppmv (or 4,100 mg ethanol/$m^3$), they had been delayed 9 and 3 times, respectively. Thus, regardless of feeding concentration, the ratios of delaying period were observed to be quite consistent each other at the exit of the adsorption column. With regard to the period of desorption, the ratios of delaying period were consistent each other to be 1.5 for both cases. In addition, the effect of microbial activity and sterilization-process was studied on adsorption equilibrium. The ethanol concentration in the vapor phase of vials packed with sterilized granular activated carbon (GAC) was quite consistent to that with unsterilized GAC. However, the ethanol concentrations in the vapor phase of vials packed with unsterilized compost and the unsterilized mixture of GAC and compost were higher than those with sterilized compost and the sterilized mixture of GAC and compost, respectively.

• Journal of Energy Engineering
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• v.8 no.4
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• pp.592-604
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• 1999

The steady state and dynamic characteristics of large cell area MCFC stacks were analyzed to solve the problems such as temperature difference generated in stacks and pressure difference between anode and cathode. Manipulated variables (current density, duel utilization rate, oxidant utilization rate) and controlled variables (temperature difference, anode and cathode pressure difference) which had an important effect on the MCFC stack performance were determined using operation results of two types of MCFC stacks (5kW (3,000 $\textrm{cm}^2$, 20 ea). 3kW (6,000 $\textrm{cm}^2$, 5ea)). The stability and transfer function representing system dynamics were obtained by steady state gain rate which showed the relative change between MVs and CVs. The transfer function was a 3$\times$3 matrix and a typical first order system without time delay. The optimal operating condition of large cell area MCFC stacks could be determined by analyzing dynamic characteristics. In case of a 5 kW MCFC stack, pressurized operation with recycle flow should be used to control the outlet temperature less than 68$0^{\circ}C$ and to control the MCFC system effectively. MIMO control or decoupler should be used to remove the interaction between MVs and CVs. This result will be used as important data in determining the control structure design and operation mode of large cell area MCFC systems in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.395-406
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• 2023

The first technological advance to improve the output and efficiency of the latest steam turbines operating in co-generation plants in Korea can be said to be progress in the field of materials that can use high-temperature, high-pressures steam. As a result of design efforts to improve the internal efficiency of steam turbines along with the development of materials, only a few manufacturers of steam turbine have produced high efficiency steam turbines. The internal efficiency of a steam turbine on the steam path operating for a long period of time is gradually lost owing to the limit of mechanical life, and efficiency and output decrease. Therefore, this study aims to develop a model that can analyze the steam flow path performance of HP (High Pressure) and IP (Intermediate Pressure) steam turbine for a co-generation plant using a commercial program and propose a performance calculation method. Owing to the complex performance calculation method of steam turbines, major variables are presented to serve as practically useful references for steam turbine practitioners. In addition, the thermal dynamic analysis(such as heat balance diagram calculation) and the the thermal dynamic calculation required for steam turbine performance calculation and the suitability of the steam turbine performance calculation results were compared with the performance test results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.473-480
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• 2011

The proton exchange membrane (PEM) fuel cell system is critically dependent on the humidity, which should be properly maintained over the entire operating range. A membrane humidifier is used for the water management in the PEMFC because of the membrane humidifier's reliable performance and zero parasitic power loss. In the PEMFC system, the membrane humidifier is required to provide appropriate humidity for the design point of the fuel cell. Although the performance of the fuel cell depends on the performance of the humidifier, few studies have provided a systematic analysis of the humidifier. We carry out an experimental analysis of the membrane humidifier using a vapor condensation bottle. The dry air pressure, water flow temperature, and air flow rate were chosen as the operating parameters. The results show that the time constant for the dynamic response of the membrane humidifier is relatively short, but additional analysis should be carried out.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.3
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• pp.169-178
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• 2006

This research aims at establishing the fundamental characteristics of the kite through the analysis of the flow field around various types of kites. The approach of this study were adopted for the analysis; visualization by CFD(computational fluid dynamics). Also, the lift/drag and PIV(particle image velocimetry) tests of kites had been performed in our previous finding. For this situation, models of canvas kite were designed by solidworks(design program) for the CFD test using the same conditions as in the lift/drag tests. And we utilized FloWorks as a CFD analysis program. The results obtained from the above approach are summarized as follows: According to comparison of the measured and analyzed results from mechanical tests, PIV and CFD test, the results of all test were similar. The numerical results of lift-coefficient and drag-coefficient were 5-20% less than those of the tests when attack angle is $10^{\circ},\;20^{\circ}\;and\;30^{\circ}$. In particular, it showed the 20% discrepancy at $40^{\circ}$. The numerical results of the ratio of drag and lift were 8-13% less than those of the tests at $10^{\circ}$ and 10% less than those of the tests at $20^{\circ},\;30^{\circ}\;and\;40^{\circ}$. Pressure distribution gradually became stable at $10^{\circ}$. In particular, the rectangular and triangular types had the centre of the high pressure field towards the leading edge and the inverted triangular type had it towards the trailing edge. The increase of the attack angle resulted in the eddy in order of the rectangular, triangular and inverted triangular type. The magnitude of the eddy followed the same order. The effect of edge-eddy was biggest in the triangular type followed by the rectangular and then the inverted triangular type. The action point of dynamic pressure as a function of the attack angle was close to the rear area of the model with the small attack angle, and with large attack angle, the action point was close to the front part of the model.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.109-117
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• 2011

The exhibition industry, as technology-intensive, eco-friendly industry, contributes to regional and national development and enhancement of its image as well, if it joins cultural and tourist industry. Therefore, We need to revitalize the exhibition industry, as actively holding an exhibition event. However, to attract a number of exhibition audience, the work of enhancing audience satisfaction and awareness of value for participation should be prioritized after improving quality of service within exhibition hall. As one way to enhance the quality of service, it is thought that the way providing personalized service geared toward each audience is needed. that is, if audience avoids the complexity in exhibition space and it affords them service to enable effective time and space management, it will improve the satisfaction. All such personalized service affordable lets the audience's preference on the basis of each audience profile registered in advance online grasp. and Based on this information, it is provided with exhibition-related information suited their purpose that is the booth for the interesting audience, the shortest path to go to the booth and event via audience's smart phone. and it collects audience's reaction information, such as visiting the booth, participating the event through offered the information in this way and location information for the flow of movement, the present position so that it makes revision of existing each audience profile. After correcting the information, it extracts the individual's preference. hereunder, it provides recommend booth and event information. in other words, it provides optimal information for individual by amendment based on reaction information about recommending information built on basic profile. It provides personalized service dynamic and interactive with audience. This paper will be able to provide the most suitable information for each audience through circular and interactive structure and designed smart-phone application supportable for updating dynamic and interactive personalized service that is able to afford surrounding information in real time, as locating movement position through sensing. The proposed application collects user‘s context information and carrys information gathering function collecting the reaction about searched or provided information via sensing. and it also carrys information gathering function providing needed data for user in exhibition hall. In other words, it offers information about recommend booth of position foundation for user, location-based services of recommend booth and involves service providing detailed information for inside exhibition by using service of augmented reality, the map of whole exhibition as well. and it is also provided with SNS service that is able to keep information exchange besides intimacy. To provide this service, application is consisted of several module. first of all, it includes UNS identity module for sensing, and contain sensor information gathering module handling and collecting the perceived information through this module. Sensor information gathered like this transmits the information gathering server. and there is exhibition information interfacing with user and this module transmits to interesting information collection module through user's reaction besides interface. Interesting information collection module transmits collected information and If valid information out of the information gathering server that brings together sensing information and interesting information is sent to recommend server, the recommend server makes recommend information through inference with gathered valid information. If this server transmit by exhibition information process, exhibition information process module is provided with user by interface. Through this system it raises the dynamic, intelligent personalized service for user.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.380-394
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• 2015

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.319-327
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• 2001

Introduction of new design tools has been required to optimally design and operate the ventilation system of long vehicle tunnels.. The demand has led to wide spread use of the simulation technique throughout the would to analysis the dynamic relationship among the variables associated with vehicle tunnel ventilation. This paper aims at performing on-site study at local tunnels to test the applicability of NETVEN, a simulation model vehicle tunnel ventilation. The study was carried out at four urban as well as highway tunnels model of vehicle tunnel ventilation. The study was carried out at four urban as well as highway tunnels employing different ventilation systems as well as traffic methods. There were some discrepancies sound between the simulation output and measurements and the following four factors are considered to mainly cause those disagreement. (1) The real situation shows distinctive transient and retarding characteristics with respect to air flow and contaminant dispersion, while ventilation forces are not steady-state and in particular those traffic and climatic variables show significant instantaneous variation. (3) Near the exit portal, the CO levels show bigger differences. The general trend is that data with higher CO concentrations carry bigger discrepancies. Turbulent diffusion is though to be the main reason for it and also contribute to the fact hat the highest CO concentrations are found at the locations somewhat inward, not at the exit portals. (4) Higher traffic rate results in higher discrepancies of ventilation velocity. Along with the exhaust characteristics, the vehicle aerodynamic characteristics need to be studied continuously in order to reduce the velocity disagreement.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.3
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• pp.115-121
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• 2012

Sapphire single crystals have been highlighted for epitaxial gallium nitride films in high-power laser and light emitting diode (LED) industries. Among the many crystal growth methods, the Kyropoulos process is an excellent commercial method for growing larger, high-optical-quality sapphire crystals with fewer defects. Because the properties and growth behavior of sapphire crystals are influenced largely by the temperature distribution and convection of molten sapphire during the manufacturing process, accurate predictions of the thermal fields and melt flow behavior are essential to design and optimize the Kyropoulos crystal growth process. In this study, computational fluid dynamic simulations were performed to examine the effects of the crucible geometry aspect ratio on melt convection during Kyropoulos sapphire crystal growth. The results through the evolution of various growth parameters on the temperature and velocity fields and convexity of the crystallization interface based on finite volume element simulations show that lower aspect ratio of the crucible geometry can be helpful for the quality of sapphire single crystal.