• Title, Summary, Keyword: Calculation of concentration

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Device Development of Mixture Concentration of Ethylene Glycol Antifreeze Coolant for Vehicles (자동차 에틸렌글리콜 부동액의 혼합 농도 측정 장치 개발)

  • Lee, Dae-Woong;Lee, Eun-Woung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.8
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    • pp.331-336
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    • 2016
  • This study presents a coolant density calculation device and its corresponding method by using a mass flowmeter and the LabVIEW program. The method can be easily measured with a mixture of coolant and by calculating the percentage of ethylene-glycol without additional investment. The cooling water is very important in a vehicle to protect the engine, and the cooling performance is affected by the mixture concentration and coolant density. The coolant density calculation device measures the mixed concentration in the anti-freeze cooling mixture made from distilled water and ethylene-glycol in real time with the mass flowmeter that is commonly attached to the radiator or heater core. The calculation program for the mixture concentration percentage was developed using the LabVIEW software. The correlation between experimental results and the calculation was conducted for a range of temperature from 40 to $90^{\circ}C$ and by varying the mixture ratio of distilled water and ethylene-glycol. As a result, the anti-freeze coolant concentration in the volume percentage is able to monitor the coolant density in a timely basis by implementing a mixture concentration calculation program without the need for additional equipment investment. The results of the calculation for the mixture concentration level show a maximum 2.7% deviation compared to the experimental results.

Calculation Method for the Concentration of Persistent Organic Pollutants (POPs) Collected by Passive Air Samplers (수동대기채취기를 이용한 잔류성유기오염물질의 농도산정)

  • Choi, Sung-Deuk
    • Journal of Korean Society for Atmospheric Environment
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    • v.29 no.2
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    • pp.217-227
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    • 2013
  • Passive air samplers (PAS) have been developed since the early 2000s and widely used for the atmospheric monitoring of persistent organic pollutants (POPs). PAS are useful especially for the investigation of source-receptor relationship of POPs because they provide higher spatial resolution data. In Korea, however, only a few research groups have conducted POPs monitoring using PAS. One of the reasons for the limited application of PAS might be due to a complicated calculation method for air concentration. In this study, therefore, we introduced the principle of polyurethane foam (PUF)-PAS, which has been most widely used in the world, and provided an example of the calculation of air concentration of polycyclic aromatic hydrocarbons (PAHs). As all data tables and equations for this calculation were provided, this method can be used for the conversion of the amount of POPs (ng) in a PUF disk to air concentration ($ng/m^3$).

Calculation of Carrier Electron Concentration in ZnO Depending on Oxygen Partial Pressure

  • Kim, Eun-Dong;Park, Jong-Mun;Kim, Sang-Cheol;Kim, Nam-Kyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.222-232
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    • 2000
  • The relationship between carrier electron concentration(n) and atmosphere oxygen partial pressure($P_{O_2}$ for pure ZnO calculated by the mass-action law, well-known as n ${\propto}P^{-1/m}_{O_2}$ where m = 4 or 6 for the single or the double ionization of the native donor defects due to its nonstoichiometry, respectively, is found in competition with the calculation result on the basis that the total defect concentration is the sum of those of unionized and ionized defects. Definitively, it is found inconsistent with the calculation result by employing the Fermi-Dirac(FD) statistics for their ionization processes. By application of the FD statistics law to the ionization while assuming the defect formation is still ruled by the mass-action law, the calculation results shows the concentration is proportional to $P^{-1/2}_{O_2}$ whenever they ionize singly and/or doubly. Conclusively we would like to propose the new theoretical relation n ${\propto}P^{-1/m}_{O_2}$ because the ionization processes of donors in ZnO should be treated with the electronoccupation probability at localized quantum states in its forbidden band created by the donor defects, i.e. the FD statistics

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Study on Exhaust Gas Composition in the Four Ctcle Gasoline Engind -Nonequilibrium Calculation of $NO_{\chi}$ - (4사이클 가솔린기관의 배기조성에 관한 연구 -$NO_{\chi}$의 비평형 계산-)

  • ;;Oh, Yeong Il
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.1 no.4
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    • pp.171-181
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    • 1977
  • This paper is aiming at calculating NOx concentration, which is one of the harmhul components of emission from the gasoline engine, formed in the combustor through the presess of combustion. Instantaneous temperature and concentration of each components for each division can be determined by the solution of simulatneous equation of reaction equation and equation of energy conservation, inputting the estimated temperature with a considerably wide rage of temperature. After determining instantaneous temperature and instantanous concentration of each components, the nonequilibrium calculation is performed based on the reaction kinetics in order to determine NOx concentration. To summarize the result abtained from the above method ;through the passage of NO concentration, NO concentration is the highest in the first division and it is gradually decreasing through the following divisions In the final division, NO concentation is the lowest.

Hydrogen Supplying System using Metal Hydride (금속 수소화물을 이용한 수소공급시스템)

  • Bae, Sang-Chul;Katsuta, Masafumi
    • 한국신재생에너지학회:학술대회논문집
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    • pp.13-19
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    • 2007
  • To find out the optimum design of hydrogen storage and supply tank using Metal Hydride (briefly MH) and to make clear the performance characteristics under various conditions are our research purpose. In order to use the low-temperature exhaust heat, $LaNi_{4.7}Al_{0.3}$ which operates under the low pressure of 1 MPa is chosen, and we measure the basic properties, namely density, specific heat, PCT(Pressure-Concentration-Temperature) characteristics, and effective thermal conductivity. Then, a numerical calculation model of hydrogen storage using MH alloy is suggested and this thermal diffusion equation of model is solved by the backward difference method. This calculation results are compared with the experimental results of the systems which installed 1kg MH alloy and, it is found out that our calculation model can well predict the experimental results. By the experimental using MH alloy, it is recognized that the hydrogen flow rate can control by the step adjustment of brine temperature.

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Stoichiometric Study for Nitrogen Removal in Anoxic-oxic Process (무산소-산소 공정에서 양론적 질소제거 연구)

  • Lee, Byung-Dae
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.11
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    • pp.1222-1227
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    • 2005
  • Optimal sludge recycling ratio for maximum total nitrogen(TN) removal efficiency was calculated stoichiometrically using nitrification and denitrification reaction with given influent water qualities in anoxic-oxic process which was one of the popular nitrogen removal system. The water quality items for stoichiometric calculation were ammonia, nitrite, nitrate, alkalinity, COD, and dissolved oxygen which could affect nitrification and denitrification. Optimal sludge recycling ratio for maximum TN removal efficiency was expressed by those five influent water qualities. TN concentration calculated stoichiometrically had kept good relationship with reported TN concentration in each tank and final effluent. In addition, it was possible to expect the TN concentration in final effluent by stoichiometric calculation within ${\pm}5.0\;mg/L$.

A Thermodynamic Calculation of Equilibrium Concentration for the CVD of SiC (SiC의 화학증착에 대한 열역학적 평형농도계산)

  • So, Myoung-Gi
    • Journal of Industrial Technology
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    • v.5
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    • pp.73-79
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    • 1985
  • Thermodynamic calculation for the CVD of SiC from methyltrichlorosilane(MTS) was done in some range of deposition condition to identify optimum condition. The results show that the most considerable chemical species are chloride and chlorosilane for silicon source and methane and acetylene for carbon source. In order to yield single phase ${\beta}$-SiC it is believed that optimum temperature range is between 1500 and $1700^{\circ}k$. With increasing temperature, stable phase is changed from Si+SiC phase to C+SiC phase. It is believed because equilibrium concentration of silicon source decrease and equilibrium concentration of carbon source increases with increasing temperature.

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A Development of Lagrangian Particle Dispersion Model (Focusing on Calculation Methods of the Concentration Profile) (라그란지안 입자확산모델개발(농도 계산방법의 검토))

  • 구윤서
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.6
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    • pp.757-765
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    • 1999
  • Lagrangian particle dispersion model(LPDM) is an effective tool to calculate the dispersion from a point source since it dose not induce numerical diffusion errors in solving the pollutant dispersion equation. Fictitious particles are released to the atmosphere from the emission source and they are then transported by the mean velocity and diffused by the turbulent eddy motion in the LPDM. The concentration distribution from the dispersed particles in the calculation domain are finally estimated by applying a particle count method or a Gaussian kernel method. The two methods for calculating concentration profiles were compared each other and tested against the analytic solution and the tracer experiment to find the strength and weakness of each method and to choose computationally time saving method for the LPDM. The calculated concentrations from the particle count method was heavily dependent on the number of the particles released at the emission source. It requires lots fo particle emission to reach the converged concentration field. And resulting concentrations were also dependent on the size of numerical grid. The concentration field by the Gaussian kernel method, however, converged with a low particle emission rate at the source and was in good agreement with the analytic solution and the tracer experiment. The results showed that Gaussian kernel method was more effective method to calculate the concentrations in the LPDM.

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An Excel Program for Dk Calculation of Contact Lens (엑셀 프로그램을 이용한 콘택트렌즈의 Dk 결정)

  • Kim, Dae Soo
    • Journal of Korean Ophthalmic Optics Society
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    • v.16 no.1
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    • pp.107-116
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    • 2011
  • Purpose: The review article was written to establish an excel program that could calculate minimal Dk of contact lens without $O^2$ deficiency and actual $O^2$ concentration on cornea when contact lens were being fitted by changing lens-related factors. Methods: An excel program was formulated to calculate the thickness of post-lens lacrimal layer, Dk of contact lens and $O^2$ concentration on cornea. Results: With the excel program established, minimal $O^2$ concentration needed on cornea could be calculated when the thickness of post-lens lacrimal layer was changed by varying lens-related factors. A different route in the excel program was needed to choose based on the shape of lacrimal layer. The thickness of lacrimal layer was determined by the shape of meniscus made of tear between lens edge and cornea with flat fit. Thus, the $O^2$ concentration showing negative number in calculation decreased on peripheral cornea with flatter fitting and actual $O^2$ concentration would be zero on cornea. With tight fitting, the thickness of post-lens lacrimal layer is much thicker than lens itself thus negative number in calculation by the excel program is shown indicating zero oxygen on cornea. It can cause $O^2$ deficiency regardless of Dk of contact lens. Conclusions: The calculation of thickness of post-lens lacrimal layer and $O^2$ concentration on cornea by the established excel program is suggested to avoid $O^2$ deficiency when fitting state is varied by changing lens-related factors.

The Finite Element Analysis on the Characteristics of the Hydrogen Diffusion for the Cr-Mo Steels (Cr-Mo강의 수소확산 특성에 관한 유한요소해석)

  • Lee, Hwi-Won;Ha, Min-Su
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.2
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    • pp.115-121
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    • 2011
  • The size of hydrogen molecule is not so small as to invade into the lattice of material, and therefore, hydrogen invades into the material as atom. Hydrogen movement is done by diffusion or dislocation movement in the near crack tip or plastic deformation. Hydrogen appeared to have many effects on the mechanical properties of the Cr-Mo steel alloys. The materials for this study are 1.25Cr-0.5Mo and 2.25Cr-1Mo steels used at high temperature and pressure. The hydrogen amount obtained by theoretical calculation was almost same with the result solved by finite element analysis. The distribution of hydrogen concentration and average concentration was calculated for a flat specimen. Also, finite element analysis was employed to simulate the redistribution of hydrogen due to stress gradient. The calculation of hydrogen concentration diffused into the material by finite element method will provide the basis for the prediction of delayed fracture of notched specimen. The distribution of hydrogen concentration invaded into the smooth and notched specimen was obtained by finite element analysis. The hydrogen amount is much in smooth specimen and tends to concentrate in the vicinity of surface. Hydrogen embrittlement susceptibility of notched specimen after hydrogen charging is more remarkable than that of smooth specimen.