• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.679-686
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• 2019

Characteristics of adsorption equilibrium, kinetic and thermodynamic of aniline blue onto activated carbon from aqueous solution were investigated as function of initial concentration, contact time and temperature. Adsorption isotherm of aniline blue was analyzed by Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich models. Langmuir isotherm model fit better with isothermal data than other isotherm models. Estmated Langmuir separation factors ($R_L=0.036{\sim}0.068$) indicated that adsorption process of aniline blue by activated carbon could be an effective treatment method. Adsorption kinetic data were fitted to pseudo first order model, pseudo second order model and intraparticle diffusion models. The kinetic results showed that the adsorption of aniline blue onto activated carbon well followed pseudo second-order model. Adsorption mechanism was evaluated in two steps, film diffusion and intraparticle diffusion, by intraparticle diffusion model. Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy for adsorption process were estimated. Enthalpy change (48.49 kJ/mol) indicated that this adsorption process was physical adsorption and endothermic. Since Gibbs free energy decreased with increasing temperature, the adsorption reaction became more spontaneously with increasing temperature. The isosteric heat of adsorption indicated that there is interaction between the adsorbent and the adsorbate because the energy heterogeneity of the adsorbent surface.

• Bulletin of the Korean Space Science Society
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• 2005.04a
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• pp.129-132
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• 2005

This paper describes BAUSAT-2 orbital thermal analysis and preliminary design of thermal control subsystem. To design thermal control subsystem of HAUSAT-2, we have considered active & passive thermal control method based on basic theory and themal equilibrium equation. Using this result, suitable thermal control method and material have been selected. We have designed thermal control subsystem based on analysis of HAUSAT-2's thermal environments on sun synchronous orbit with altitude 650km, inclination $98^{\circ}$ and thermal distribution and range expectation of each HAUSAT-2's surface. Thermal analysis consists of system level, box level and board level analysis. We have completed system level and box level analysis. Till now, board level analysis of main heat dissipation board in progress. Thermal control subsystem has designed according to thermal analysis result. This design is to maintain all of the HAUSAT-2 components within the allowable temperature limits. In future, STM

• Journal of Energy Engineering
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• v.10 no.4
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• pp.349-356
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• 2001

Phenomenon of direct contact condensation (DCC) heat transfer between steam and water is characterized by the transport of heat and mass through a moving steam/water interface. Since the DCC heat transfer provides some advantageous features in the viewpoint of enhanced heat transfer, it is widely applied to the diversified industries. This study proposes a simple condensation model on the stable steam jets discharging into a quenching tank with subcooled water from a single horizontal pipe for the prediction of the steam jet shapes. The model was derived from the mass, momentum and energy equations as well as thermal balance equation with condensing characteristics at the steam/water interface for the axi-symmetric coordinates. The extremely large heat transfer rate at the steam/water interface was reflected in the effective thermal conductivity estimated from the previous experimental results. The results were compared with the experimental ones. The predicted steam jet shape(i. e. radius and length) by the model was increasing as the steam mass flux and the pool temperature were increasing, which was similar to the trend observed in the experiment.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.51-54
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• 2013

Rotary kiln reactors are frequently equipped with an axial burner with which solid burden material is directly heated. Lifters are commonly used along the length of the system to lift particulate solids and increase the heat transfer between the solid bed and the combustion gas. The material cascading from the lifters undergoes drying and reacting through direct contact with the gas stream. In this study, volume distribution of materials held within lifters was modeled according to the different lifter configuration and appropriate configuration was used for the design purpose. This was applied to the one-dimensional heat balance model of a counter-current flow reactor, which contributes to the increase of the effective contact surface, and thereby enhances the heat transfer.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.28.3-28.3
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• 2009

과학기술위성 3호는 2007년 6월에 사업착수를 시작하여, 동년 8월 시스템요구사항검토회의(SRR)를 통해 임무 요구사항을 도출하였고, 동년 12월에 시스템기본설계검토회의(SDR)과 2008년 9월 시스템예비설계검토회의(PDR)를 개최하여 시험인증모델(EQM, Engineering& Qualification Model) 제작을 시작하여, 납품을 완료하고 ETB(Engineering Test Bed)상에서 유닛의 기능 시험 및 접속시험, 그리고 환경시험을 수행을 완료하였다. 또한 열구조모델 (STM, Structure and Thermal Model)도 제작을 완료하고 발사환경시험과 열평형 환경시험을 완료하였다. 이와같이 시험인증모델 및 열구조모델에 대한 지상에서의 시험과 검증이 완료된 시험결과를 바탕으로 2009년 9월 상세설계를 완료하고 비행모델 제작에 착수할 예정이다. 이 논문에서는 과학기술위성 3호의 시험인증모델에 대한 시험의 목적, 종류 그리고 검증에 대한 결과 그리고 향후 계획에 대해 발표하고자 한다. 참고로 과학기술위성 3호는 주탑재체인 다목적적외선영상시스템(MIRIS)은 우리 은하계의 근적외선 관측, 우주 배경복사 관측 및 지구 지표면의 적외선 영상 획득을 임무로 하고 있고, 부탑재체인 초소형 영상 분광기(COMIS)는 한반도 지역의 다중 스펙트럼 영상을 획득함으로써 대기관측 및 환경감시의 임무를 가지고 있다.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.435-445
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• 2023

A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

• Journal of Bio-Environment Control
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• v.2 no.2
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• pp.99-109
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• 1993

Cooling of nutrient solution is essential to improve the growth environment of crops in hydroponic culture during summer season in Korea. This study was carried out to provide fundamental data for development of the cooling system satisfying the required cooling load of nutrient solution in hydroponic greenhouse. A numerical model for prediction of the cooling load of nutrient solution in hydroponic greenhouse was developed, and the results by the model showed good agreements with those by experiments. Main factors effecting on cooling load were solar radiation and air temperature in weather data, and conductivity of planting board and area ratio of bed to floor in greenhouse parameters. Using the model developed, the design cooling load of nutrient solution in hydroponic greenhouse of 1,000$m^2$(300pyong) was predicted to be 95,000 kJ/hr in Suwon and the vicinity.

• ETRI Journal
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• v.13 no.4
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• pp.42-51
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• 1991

MBE 성장시 기판 표면에서의 성장과정을 운동론적 지배과정과 열역학적 지배과정으로 나누어 성장모델을 제시하였으며, 화학적 평형상태에서의 열역학이 III-V compound의 성장속도와 composition 에 미치는 영향을 기존의 보고된 결과 데이터와 비교 분석하였다. 특히 miscibility gap 내에 존재하는 III-V ternary compound의 경우 박막의 성질 및 소자의 특성에 영향을 미치는 alloy clustering은 저온 성장시 surface kinetics에 의해, 고온성장시에는 열역학적 spinodal decomposition에 의해 결정됨을 알수 있었다. 열역학적 모델에서는 기판과 layer사이의 lattice mismatch와 재료의 elastic coefficient의 함수인 additive strain Gibbs free energy, 그리고 ternary solid solution의 regular behavior를 가정하여 ternary alloy의 mixing에 기인한 excess Gibbs free energy를 고려하였다.

• Journal of the Korean earth science society
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• v.23 no.8
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• pp.676-682
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• 2002

The concept of sensible temperature in winter is an attempt to quantify the sensation of cold by dry-bulb temperature combined with wind speed. Siple-Passel’s windchill equivalent temperature originated in experiments that are not conformable to various human conditions. Therefore, many investigators have found the flaws which are listed. Steadman’s model is based on the concept of thermal equilibrium and more sound and more representative of human conditions. But no classifications exist for Steadman’s windchill equivalent temperature, yet. The JAG/TI-model which was developed by US and Canada is more accurate, easy to understand and reflects human beings by conducting experiments using human volunteers but didn't take into account solar radiation, wet condition and physical state of the individual. Because of individual differences in people’s age, activity, health, metabolic rate, etc., no experimental evidence exists to suggest whether Siple-Passel’s, Steadman’s and JAG/TI-model’s windchill equivalent temperature is more applicable to the majority of people. Therefore we need the windchill model which is best applicable to Korean Army.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.23-29
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• 2003

Transonic two-phase flow of Saturated humid air, in which relative humidity is 100%, with various condensation processes around thin airfoils is investigated. The study uses an extended transonic small-disturbance(TSD) model of Rusak and Lee [11, 12] which includes effects of heat addition to the flow due to condensation. Two possible limit types of condensation processes are considered. In the nonequilibrium and homogeneous process, the condensate mass fraction is calculated according to classical nucleation and droplet growth rate models. In the equilibrium process, the condensate mass fraction is calculated by assuming an isentropic process. The flow and condensation equations are solved numerical1y by iterative computations. Results under same upstream conditions describe the flow structure, field of condensate, and pressure distribution on airfoil's surfaces. It is found that flow characteristics, such as position and strength of shock waves and airfoil’s pressure distribution, are different for the two condensation processes. Yet, in each case, heat addition as a result of condensation causes significant changes in flow behavior and affects the aerodynamic performance of airfoils.