• Transactions on Electrical and Electronic Materials
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• 제15권6호
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• pp.333-337
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• 2014

In this study, the use of a discharging process for charged particles is proposed to achieve an ideal electrical balance or neutralization and to improve the electrical and optical properties of a reflective electronic display. Here, negatively charged particles (white) and positively charged particles (black) are used. The q/m (charge per mass for a particle) values of the black and white particles are $+4.5{\mu}C/g$ and $-4.5{\mu}C/g$, respectively. We compared the movement of the charged particles by varying their discharging time. Stable movement of the charged particles is obtained with an appropriate discharging time, which resulted in improvements of the optical properties of the panel.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.843-847
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the imbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize imbalance correction process time.

• 한국소음진동공학회논문집
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• 제17권8호
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• pp.720-725
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the unbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize unbalance correction process time.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.43-48
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• 2001

Combustor design technique is established by reverse engineering of existing combustor and applying heat & mass balance equations for the combustion process. The ratio of entrained air for each air slot is found to be almost proportional to the area ratio from the result of numerical simulation. The shape of the combustor is modified by the numerical analysis to get circumferentially uniform flow inside the combustion chamber required for the flame stability.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.155-163
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• 1999

A numerical study for simulating a swirling pulverized coal combustion in axisymmetric geometry is done here by applying the weighted sum of gray gases model (WSGGM) approach with the discrete ordinate method (DOM) to model the radiative heat transfer equation. In the radiative transfer equation, the same polynomial equation and coefficients for weighting factors as those for gas are adopted for the coal/char particles as a function of partial pressure and particle temperature. The Eulerian balance equations for mass, momentum, energy, and species mass fractions are adopted with the standard ${\kappa}-{\varepsilon}$ turbulence model, whereas the Lagrangian approach is used for the particulate phase for soot. The eddydissipation model is employed for the reaction rate for gaseous mixture, and the single-step first-order reaction model for the devolatilization process for coal. By comparing the numerical results with experimental ones, the models used here are confirmed and found to be one of good alternatives for simulating the combustion as well as radiative characteristics.

• 한국식품영양학회지
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• 제10권4호
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• pp.462-467
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• 1997

최근 건조 및 탈수공정으로 사용되고 있는 침지(soaking)에 의한 방법인 DIS 공정(dewatering and impregnation soaking process)은 상온에서 침지용액에 식품시료를 담금으로서 시료내의 수분이 탈수되는 현상을 이용한 공정으로서 이 때 용액 속의 용질들이 시료 속의 세포 내로 침투하는 확산현상도 동시에 발생한다. 따라서 영양분의 손실과 관능적 품질저하를 억제할 수 있으며, 건조시의 에너지를 절감하는 등의 특성을 갖는다. DIS 공정에서는 용질의 크기에 따라 원형질막 분리현상과 세포벽 붕괴현상이 발생하며, 시료의 조직상태와 운전조건에 의하여 그 탈수 정도는 차이가 나타난다. DIS 공정을 제어하기 위한 모형화는 주로 비정상상태에서의 Fick의 법칙과 물질수지를 기초로 한 여러 가지 모델들이 제안되어 등온상태에서 시간에 따른 탈수량과 용질 침투량을 정확히 예측하고자 하고 있다.

• Journal of Microbiology and Biotechnology
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• 제12권3호
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• pp.377-381
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• 2002

Recently, interests to remove nitrogen in the nitritation process have increased because of its economical advantages, since it could be a short-cut process to save both oxygen for nitrification and carbon for denitrification compared to a typical nitrification. However, the kinetics related with the nitritation process has not yet been fully understood. Furthermore, many useful models which have been successfully used for wastewater treatment processes cannot be used to estimate effluent nitrite concentration for evaluating performance of the nitritation process, since the process rate equations and population of microorganisms for nitrogen removal in these models have been set up only for the condition of full nitrification. Therefore, the present study was conducted to estimate an effluent nitrite concentration in the nitritation process with a concept of enzymatic inhibition kinetics based on long-term laboratory experiments. Using a nonlinear least squares regression method, kinetic parameters were accurately determined. By setting up a process rate equation along with a mass balance equation of the nitrite-oxidizing step, an effluent nitrite concentration in the nitritation process was then successfully estimated.

• 대한기계학회논문집B
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• 제23권5호
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• pp.670-677
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• 1999

An analysis of generation and growth of multicomponent particles has been carried out to predict the size and composition distributions of particles generated in the Modified Chemical Vapor Deposition(MCVD) process. In MCVD process. scale-up of sintering and micro-control of refractive index may need the Information about the size and composition distributions of $SiO_2-GeO_2$ particles that are generated and deposited. The present work solved coupled steady equations (axi-symmetric two dimensions) for mass conservation, momentum balance. energy and species(such as $SiCl_4$, $GeCl_4$, $O_2$, $Cl_2$) conservations describing fluid flow. heat and mass transfer in a tube. Sectional method has been applied to obtain multi-modal distributions of multicomponent aerosols which vary in both radial and axial directions. Chemical reactions of $SiCl_4$ and $GeCl_4$ were included and the effects of variable properties have also been considered.

• Journal of Welding and Joining
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• 제35권2호
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• pp.13-22
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• 2017

In laser full penetration welding process, full penetration hole(FPH) is formed as a result of force balance between the vapor pressure and the surface tension of the surrounding molten metal. In this work, a three-dimensional numerical model based on a conserved-mass level-set method is developed to simulate the transport phenomena during laser full penetration welding process, including full penetration keyhole dynamics. Ray trancing model is applied to simulate multi-reflection phenomena in the keyhole wall. The ghost fluid method and continuum method are used to deal with liquid/vapor interface and solid/liquid interface. The effects of processing parameters including laser power and scanning speed on the resultant full penetration hole diameter, laser energy distribution and energy absorption efficiency are studied. The model is validated against experimental results. The diameter of full penetration hole calculated by the simulation model agrees well with the coaxial images captured during laser welding of thin stainless steel plates. Numerical simulation results show that increase of laser power and decrease of welding speed can enlarge the full penetration hole, which decreases laser energy efficiency.

• 한국추진공학회지
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• 제4권4호
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• pp.9-17
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• 2000

준안정상인 $\beta$형 HNIW의 용해와 안정상인 $\varepsilon$형 HNIW의 성장 특성을 고려한 모델식을 물질수지와 한께 계산하는 방법으로 결정성장 속도와 용해 속도를 계산하였다. 제시된 모델은 용액을 매체로 하여 진행되는 $\beta$$\longrightarrow$$\varepsilon$전이 현상에 대한 속도론적 데이터를 모사 하는데 유용하였다. 2 단 모델을 이용한 유효 인수로부터, 격정성장 과정에서 표면 축적 단계의 영향은 작으며, 확산 의존성은 ethyl acetate와 chloroform의 혼합 용매 중 chloroform의 함량이 증가함에 따라 감소함을 보였다. 이들 속도론 적 계수들을 이용한 수치모사를 통하여 $\varepsilon$-HNIW의 입자 크기를 예측하는 것이 가능하였다.