• Journal of Energy Engineering
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• v.12 no.4
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• pp.289-301
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• 2003

To develop a chemical-looping combustion technology, conceptual design of 50 kW thermal chemical-looping combustor, which is composed of two interconnected pressurized circulating fluidized beds, was performed by means of mass and energy balance calculations. A riser type fast fluidized bed was selected as an oxidizer and a bubbling fluidized bed was selected as a reducer by mass balance for the chemical-looping combustor. Calculated values of bed mass, solid circulation flux, and reactor dimension by mass and energy balance calculations were suitable for construction and operation of chemical-looping combustor. It is concluded from the comparison of the design results and operating values of commercial circulating fluidized bed that the process outline is realistic. Moreover, the previous results support that oxygen carrier particle, NiO/bentonite, fulfills the conversion rates needed for the proposed design. The effects of system capacity, metal oxide content in a oxygen carrier particle, amount of steam input, gas velocity, and solid depth on design values were investigated and the changes in the system performance can be estimated by proposed design tool.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.266-269
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• 2005

This study targeted methane production and decrease of organic materials concentration by high temperature anaerobic digestion of food waste. A anaerobic reactor with circulation was employed and the operation condition as follows: high temperature of $45{\pm}2,$ 0.6 $kg-VS/m^3/d,$ HRT of 70 days, pH of $6.8{\sim}7.2$. The CODcr removal rate of $75%{\sim}85%$ with effluent of $14,000{\sim}19,000$ mg/L in case of influent of $75,000{\sim}95,000$ mg/L showed. In influent TS(Total Solid) and VS(Volatile Solid) concentration of $2.94%{\sim}5.09%,$ and $2.98{\sim}5.01%,$ the effluent concentration was $0.65{\sim}1.1%$ and $0.6%{\sim}0.8%,$ respectively. 0.28 $m^3-CH_4$ / kg-VS was averagely obtained in the system.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.5
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• pp.608-619
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• 1998

The small and the large intestine of swine represent the organs that extract nutrients from feedstuffs through digestion and fermentation and that allow their absorption and incorporation into the blood circulation. Special attention is directed towards the small intestine of young pigs since the transition to a solid diet at weaning exerts major impacts on the structural and functional integrity of the small intestine. Dietary factors involved in postweaning changes of gut morphology and biochemistry such as removal of bioactive compounds in sows milk at weaning, anti-nutritional factors in weaner diets, dietary fiber and the role of voluntary feed intake will be elucidated. The microbial function of the large intestine which is carried out by a diverse population of microorganisms is dependent on substrate availability. Short chain fatty acids as main fermentation products contribute to the energy supply of the host but they are also important for the maintenance of the morphological and functional integrity of the epithelium in the colon. As a result of bacterial nitrogen assimilation in the large intestine, nitrogen is shifted from the urinary to the fecal excretion route thus saving metabolic energy to the pig because less ammonia would become available for conversion to urea.

• The KSFM Journal of Fluid Machinery
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• v.10 no.1 s.40
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• pp.56-63
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• 2007

Because the mixing efficiency is influenced remarkably by varying the geometrical configurations, the study of flow characteristics inside the mechanical agitator is very important to improve the performances. The draught tube in the agitator makes intermixing between the screw and tube by interrupting radial flow, and it makes circulation region in a mixing chamber. In general, the helical screw agitator with a draught tube (HSA) is proved more efficient to mix than the others. Consequently, such as the shapes of helical screw, number of pitches and the variation of angular velocity are the main parameters for improving the capacity of HSA. And also the suspension of the solid particles in the agitator can be determined these parameters. The rate of solids suspension in the mixing chamber was quantified with a statistical average value, of. Numerical analyses were carried out, using a commercial CFD code, Fluent, to obtain the velocity, pressure and particle distributions under steady, laminar flow and no-slip conditions. Results are graphically depicted with various parameters.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.313-324
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• 2004

A rich phenomenon in the dynamics of azimuthal vortices in a circular cylinder caused by the inertial oscillation is investigated numerically at high Reynolds numbers and moderate Rossby numbers. In the actual spin-up flow where both the Ekman circulation and the bottom friction effects are included, the first appearance of a seed vortex is generated by the Ekman boundary-layer on the bottom wall and the subsequent roll-up near the corner bounded by the side wall. The existence of the small vortex then rapidly propagates toward the inviscid region and induces a complicated pattern in the distribution of azimuthal vorticity, i.e. inertial oscillation. The inertial oscillation however does not deteriorate the classical Ekman-pumping model in the time scale larger than that of the oscillatory motion. Motions of single vortex and a pair of vortices are further investigated under a slip boundary-condition on the solid walls. For the case of single vortex, repeated change of the vorticity sign is observed together with typical propagation of inertial waves. For the case of a pair of vortices with a two-step profile in the initial azimuthal velocity, the vortices' movement toward the outer region is resisted by the crescent-shape vortices surrounding the pair. After touching the border between the core and outer regions, the pair vortices weaken very fast.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.190-207
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• 2015

In the combustion engineering, to decrease pollution and increase production efficiency, and to optimally keep solid burning material amount constant in a burner online, it needs a smart method to detect the amount variation of the burning materials in a high temperature environment. This paper presents an online machine vision system for automatically measuring and detecting the burning material amount inside a burner or a boiler. In the camera-protecting box of the system, a sub-system for cooling is constructed by using the cooling water circulation techqique. In addition, the key and intelligent step in the system is to detect the pile profile of the variable burning material, and the algorithm for the pile profile tracing was studied based on the combination of the gey level (color) discontinuity and similarity based image segmentation methods, the discontinuity based sub-algorithm is made on the quaternion convolution, and the similarity based sub-algorithm is designed according to the region growing with multi-scale clustering. The results of the two sub-algoritms are fused to delineate the final pile profile, and the algorithm has been tested and applied in different industrial burners and boilers. The experiements show that the proposed algorithm works satisfactorily.

• Journal of Korean Society of Rural Planning
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• v.23 no.1
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• pp.165-174
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• 2017

Four requirements for the operating and supporting system for sustainable landscape management will be discussed through this paper. The requirements are based on multiple case studies on the structure and the process of development of three organizations that have been contributing to the sustainable rural landscape management in Japan since 1989. The first requirement is that the residents should recognize regional problems and voluntarily organize a group which can properly deal with the problems. Secondly, members of the organization should have a solid grasp of the goal of their activities (or founding principal of the organization) and share it among themselves. Founding principal should include the history of natural circulation system in the area, cultural features and a future plan in association with human resources. Thirdly, the administration of the organization should be separated from the founder, the residents. The administration, such as business promotion, becomes more effective when consigned to a separate entity, not to the residents. Lastly, the interaction among separate entities is crucial to promote diverse activities for the local landscape management. The administrators and experts need to cooperate to draw a precise conclusion regarding the way of interaction. These requirements drawn from the Japanese case studies should be localized to the Korean circumstances for further adoption.

• Journal of Radiation Protection and Research
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• v.14 no.2
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• pp.18-22
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• 1989

In order to calibrate the CR-39 Solid State Nuclear Track Detector (SSNTD), a closed -circulation type SSNTD-Calibration-System containing a radon-cup with the Millipore filter has been set-up, and the tracks produced on the SSNTD were measured for the known amount of radon concentration. Calibration factor for the time integrated radon concentration as a function of the track density on CR-39 was estimated to be $0.24{\pm}0.09(pCi/l)\;day/(Tr/cm^2)$.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.493-498
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• 2008

Particles or deposit formed by corrosion of the pipe material bring about bad influences on the heating systems with inconvenience, energy loss and so on. In order to obtain the non-corrosive environments, the circulation hot water should properly be treated in several ways to satisfy one or more conditions of the followings: suitable pH-level, low hardness, low oxygen content, low conductivity, low level of chlorides and sulphur compounds and low level of solid particles. This experimental study was carried out to develope the new guidelines on the optimal water quality and directions for water quality management in heating systems. As results, it was recommended that the heating water be maintained pH-level not less than 8, hardness contents as $CaCO_3$ no more than 50 mg/L, turbidity no more than 10 NTU and T-Fe contents 1 mg/L below.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.4
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• pp.123-131
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• 1997

Since the industrial revolution. the growth of cities has been especially apid and the rate of ulbanization has been high. This urban development is encroaching on the natural environment because the cities are developed with not only residential estates, industrial area and buildings but also with infrastructure. The surface area of the city is sealed ,with pavement whereas nature is disturbed and modified. The hydrological cycle in the city is inf1uenced by the change of land use I. e., from forest to agricultural land, talc draining of wetlands and above all the increase of built-up areas. The surface retention and interception of precipitation in the city is reduced. because the surface area is now smooth and solid. The characteristics of the hydrological cycle in the city are increased runoff, reduced evapotranspiration and infiltraction . We have too much faith in technology although it may cause more unforseen problems. We build more river banks and 'emulation dams and straighten rivers and streams in order to protect ourselves from disasters.. However. the results of hose developments are often higher$.$ water levels, the disturbance of aquatic ecosystems and the reduction of biodiversity. Therefore, we should examine problems from the hydrological cycle in cities and study a natural system as close cities to nature as possible. This paper shows the problems caused by the hydrological cycle in the city. The ecology-oriented method and design must be used in order to protect our environment from dicturbance.