• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.137-138
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• 2012

The two-equation soot model based on the transient laminar flamelet model is implemented for soot formation of laminar non-premixed $CH_4/Air$ flame with detailed chemical reaction mechanism and complex thermodynamic properties. The soot model represents nucleation, growth and oxidation with gas-phase chemistry. This represented unsteady flamelet soot model has been tested and compared using well verified reference calculation result obtained solving the Full Transport Equations method.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.218-227
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• 1998

Present study is undertaken to optimize the lubrication reliability and frictional loss of the dynamically-loaded journal bearing in hermetic reciprocating compressor with alternative refrigerant R600a application. Thermodynamic and dynamic analysis has been conducted to investigate cylinder pressure variations by substitution alternative refrigerant R600a for R12. The modeling of the dynamics of the compressor mechanism has been performed with lumped mass method. A mathematical model is developed for analyzing the dynamics of the journal bearing system with the mobility method. It takes into account the effects of the refrigerant species, aspect ratio, clearance ratio and surface roughness. A corresponding computer program is described which enables to obtain the minimum film thickness and frictional loss. Design optimization is graphically performed by parametric studies of the aspect ratio and clearance ratio.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.255.2-255.2
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• 2014

Electrode erosion is indispensable for atmospheric plasma systems, as well as for switching devices, due to the high heat flux transferred from arc plasmas to contacts, but experimental and theoretical works have not identified the characteristic phenomena because of the complex physical processes. Our investigation is concerned with argon free-burning arcs with anode erosion at atmospheric pressure by computational fluid dynamics (CFD) analysis. We are also interested in the energy flux and temperature transferring to the anode with a simplified unified model of arcs and their electrodes. In order to determine two thermodynamic quantities such as temperature and pressure and flow characteristics we have modified Navier-Stokes equations to take into account radiation transport, electrical power input and the electromagnetic driving forces with the relevant Maxwell equations. From the simplified self-consistent solution the energy flux to the anode can be derived.

• 설비공학논문집
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• 제13권8호
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• pp.771-779
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• 2001

In this study, a simulation program has been developed to predict the performance of a parallel flow condenser of an air conditioning system for an automobile. The well-known correlations for he heat transfer rates and the pressure drops are included in this model. It is fond that the numerical model can predict the heat transfer rate and the pressure drop accurately. As the condensing pressure increases of fixed air inlet temperature, the heat transfer rate increases and the pressure drop decreases. The effect of he degree of subcooling on the performance of the condenser is greater than that of the degree of super-heating because the ratio of the area occupied by he tow-phase refrigerant the total area is significantly affected by he degree of subcooling rather than the degree of superheating.

• 설비공학논문집
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• 제12권11호
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• pp.1020-1030
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• 2000

A crossflow finned tube evaporator has been investigated using tube-by-tube method. The refrigerant flows inside tubes while the air passes outside the finned tue. R134a for a refrigerant and wet air were used in this analysis. Three refrigerant circuitries, complex or simple, were compared. The effects of refrigerant circuitry and airside condensation on thermal performance such as heat transfer rate, enthalpy of refrigerant, temperature of refrigerant and air, pressure of refrigerant and average condensate layer thickness were investigated. It was found that this method could be applied to the analysis of finned tube evaporator for dehumidification and air conditioning.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 추계학술대회 논문집
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• pp.193-195
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• 2008

As arising the cost and decreasing of gasoline and fossil fuel, renewable energy sources such as photovoltaics, wind and fuel cell have been interested. Among of them, PEM fuel cells are good energy sources to provide reliable power at steady state regardless of weather, time of day and location as long as the fuel and air are supplied, but they cannot respond to electrical load transients as fast as desired. This is mainly due to their slow internal electrochemical and thermodynamic responses. Therefore, to use the fuel cells with high efficiency, this paper finds characteristic curve and understand operation of PEMFC based on three theoretical approaches such as activation, ohmic and concentration and make the model using MATLAB. That result was compared with real system to certify.

• Bulletin of the Korean Chemical Society
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• 제11권5호
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• pp.367-371
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• 1990

The near-IR spectra of thioacetamide were recorded for the investigation of hydrogen bonding between thioacetamide (TA) and N,N-dimethylalkylamides (DMF, DMA, DMP) in chloroform over the range of 5$^{\circ}C$ to 55$^{\circ}C$. The ${\nu}_{\alpha}$ + amide II combination band has been resolved into contributions from monomeric TA, 1:1 hydrogen bonded complex and 1:2 complex by the parameterized matrix modeling method. The association constants ($K_c$) of the complex have been obtained at various temperatures and used to determine the thermodynamic parameters for the hydrogen bonding by the usual Van't Hoff method. It was found that N,N-dimethylalkylamide forms less stable hydrogen bonded complex with TA in chloroform than in carbon tetrachloride.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.93-105
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• 2012

본 연구에서는 무기염인 NaCl, KCl, $NaNO_3$ 및 $KNO_3$의 각 전해질과 L형 아미노산인 L-Valine 및 L-Proline이 용해된 아미노산/전해질 수용액에서 L-Valine 및 L-Proline의 활동도계수와 용해도를 298.15 K에서 측정하였다. 아미노산의 활동도계수는 양이온 및 음이온의 선택성 전극간의 기전력을 측정하는 전기화학 법으로 측정하였으며, 용해도는 아미노산의 고체상과 상평형을 이루고 있는 포화용액을 중량 분석하여 측정하였다. 실험적으로 측정된 전해질 및 아미노산의 활동도계수 값을 본 연구의 저자들이 수행한 지난번 연구[Korean Chem. Eng. Res. 48(4), 519(2010)]의 이론적 모델로 검토하였다. 실험을 수행한 8개의 아미노산/전해질 수용액에서 측정된 전해질 및 아미노산의 활동도계수 값은 지난번 연구의 이론적 모델에 잘 적용되는 경향을 보였으며, 또한 측정된 아미노산의 용해도 데이터도 지난번 연구의 이론적 관계로 잘 묘사될 수 있었다.

• Nuclear Engineering and Technology
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• 제31권2호
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• pp.182-191
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• 1999

The sorption of UO$_{2}$$^{2+}$ onto goethite and kaolinite under various experimental conditions was successfully interpreted using surface complexation modeling (SCM). The SCM approach used in this work is the triple-layer model (TLM) in which weakly bonded ions are modeled as outer-sphere (ion-pair) complexes and strongly bonded ions as inner-sphere (surface coordination) complexes. The change of ionic strength did not affect the U(VI) sorption onto goethite, thus the formation of inner-sphere surface complexes, (FeO)$_2$UO$_2$ and (FeO)$_2$(UO$_2$)$_3$OH$_{5}$ was assumed to simulate the effects of ionic strength and goethite concentration. On the other hand, the U(VI) sorption onto kaolinite showed ionic strength dependence, thus the formation of AlO-UO$_{2}$$^{2+}$(outer-sphere complex) and SiO(UO$_2$)$_3$OH$_{5}$ (inner-sphere complex) was assumed to simulate the experimental data. In the presence of carbonates, the sorption of U(VI) onto kaolinite decreased in the weakly alkaline pH range. This was well simulated assuming the formation of a outer-sphere surface complex, A1OH$^{2+}$- (UO$_2$)$_2$CO$_3$OH$_3$. Since SCM approach uses thermodynamic data such as surface complexation constants, it is more predictive than empirical modeling approach in which conditional values such as partition coefficient are used. used.

• 동의생리병리학회지
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• 제16권2호
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• pp.365-372
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• 2002

The mineral medicines mean a sort of mineral or rock for medical treatment and natural material using their chemical components and physical properties. In this study, it was apprehended the mineralogical characteristics of As-bearing group mineral medicines. The extraction test is an vitro test system for predicting the bioavailability of the major and minor elements from mineral medicines and incorporates gastrointestinal tract parameters representative of a human(including stomach and small intestinal pH, stomach mixing time and velocity). The results of the extraction test are used for reaction path modeling in human body. Reaction path modeling in human body can predict digestion with gastric juice as well as bioavailability, speciation. Also, it can predict accumulation of arsenic as pH condition. As the results of the extraction test for digestion, the amounts of Fe extraction was the highest, followed by As, Ca, Ni. In addition, as the results of the reaction path modeling between arsenic compounds and gastric juice using thermodynamic data, when absorbed, major species are followed by H₃As₃S/sub 6/(aq), As₃S/sub 6/ (aq), AsO/sup +/, H₂As₃S/sup 6-/, H₂AsO/sup 3-/, HAs₃S6/sup 2-/, HAsO/sub 3//sup 2-/ and AsO/sub 3//sup 3-/. Specifically the concentration of H₃As₃S/sub 6/(aq) is the highest. As pH increases, the concentration of H₂AsO/sup 3-/, HAsO/sub 3//sup 2-/, HAsO/sub 3//sup 3-/, HAs₃S/sub 6//sup 2-/, H₂As₃S/sup 6-/, and H₃As₃S/sub 6/ increases, whereas the concentration of H₃As₃S/sub 6/ and AsO/sup +/ decreases. On the results of this study, it is able to find out effective and toxic components of poisonous arsenic group of mineral medicines and expected to be widely used for the development of new medicines.