• Nuclear Engineering and Technology
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• 제37권6호
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• pp.525-536
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• 2005

The interfacial area transport equation dynamically models the changes in interfacial structures along the flow field by mechanistically modeling the creation and destruction of dispersed phase. Hence, when employed in the numerical thermal-hydraulic system analysis codes, it eliminates artificial bifurcations stemming from the use of the static flow regime transition criteria. Accounting for the substantial differences in the transport mechanism for various sizes of bubbles, the transport equation is formulated for two characteristic groups of bubbles. The group 1 equation describes the transport of small-dispersed bubbles, whereas the group 2 equation describes the transport of large cap, slug or chum-turbulent bubbles. To evaluate the feasibility and reliability of interfacial area transport equation available at present, it is benchmarked by an extensive database established in various two-phase flow configurations spanning from bubbly to chum-turbulent flow regimes. The geometrical effect in interfacial area transport is examined by the data acquired in vertical fir-water two-phase flow through round pipes of various sizes and a confined flow duct, and by those acquired In vertical co-current downward air-water two-phase flow through round pipes of two different sizes.

• Journal of Preventive Medicine and Public Health
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• 제28권1호
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• pp.73-84
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• 1995

대구시내 중심가의 국민학교 4학년 학생 남녀 각 50명씩들을 대상으로 혈액, 두발 및 조갑 내의 연농도를 정량분석하고 이들 각 시료 내의 연농도의 상관관계를 조사한 연구결과를 요약하면 다음과 같다. 혈액, 두발 및 발들의 평균 연농도는 각각 $6.00{\pm}2.44{\mu}g/dl,\;7.17{\pm}3.28{\mu}g/g,\;7.33{\pm}3.18{\mu}g/g$이었다. 혈중 연농도는 남학생이 $6.43{\pm}2.77{\mu}g/dl$, 여학생이 $5.59{\pm}2.01{\mu}g/dl$, 두발 중 연농도는 남학생이 $7.66{\pm}2.97{\mu}g/g$, 여학생이 $6.68{\pm}3.54{\mu}g/g$로 남학생에서 높았으나 통계적으로 유의하지 않았으며, 발톱의 경우는 남학생에서 $8.19{\pm}3.54{\mu}g/g$, 여학생에서 $6.47{\pm}2.59{\mu}g/g$로 남학생에서 유의하게 높았다. 혈액, 두발과 발톱 중 연농도에 따른 학생들의 분포는 혈액은 남학생에서 $5.0\sim7.4{\mu}g/dl(38%)$, 여학생에서는 $2.5\sim4.9{\mu}g/dl(42%)$에 전체적으로는 $5.0\sim7.4{\mu}g/dl(41%)$에 가장 많이 분포하였다. 두발의 경우 남학생에서 $5.0\sim7.4{\mu}g/g(32%)$, 여학생에서 $2.5\sim4.9{\mu}g/g(34%)$에 전체적으로는 $2.5\sim4.9{\mu}g/g(28%)$에 가장 많이 분포하였다. 발들에서는 남학생에서 $5.0\sim7.4{\mu}g/g(34%)$, 여학생에서 $7.5\sim9.9{\mu}g/g(30%)$에 전체적으로는 $5.0\sim7.4{\mu}g/g(31%)$에 가장 많이 분포하였다. 또한 남학생의 8%, 여학생의 4%로 전체 학생들의 6%에서 혈액 중 연농도가 $10{\mu}g/dl$을 넘었다. 혈액, 두발과 발톱 사이의 연농도의 상관관계를 보면 남학생에서 혈액과 두발의 연농도 사이의 상관계수는 0.4909(p<0.001)(regression equation : Y(두발 중 연농도)=0.5255X(혈액 중 연농도)+4.2810)였으며, 여학생에서의 상관계수는 0.3778(p<0.001) (regression equation : Y(두발 중 연농도)=0.6655X(혈액 중 연농도)+2.9632)이었다. 남학생에서 혈액과 발톱 중 연농도 사이의 상관계수는 0.5533(p<0.01) (regression equation : Y(발톱 중 연농도)=0.7076X(혈액 중 연농도)+3.6472)였으며 여학생에서의 상관계수는 0.2738(regression equation : Y(발톱 중 연농도)=0.3431X(혈액 중 연농도)+4.5570이었다. 남학생에서 두발과 발톱 중 연농도 사이의 상관계수는 0.4148(p<0.001) (regression equation : Y(발들 중 연농도)=0.4956X(두발 중 연농도)+4.3986)였으며, 여학생에서의 상관계수는 0.1159(regression equation : Y(발톱 중 연농도)=0.0825X(두발 중 연농도)+5.9214)이었다. 본 연구의 결과에서 여학생의 두발과 발톱간을 제외하고, 대도시 남자 국민학교 학생들의 혈액, 두발, 발들의 연농도간의 유의한 관련성이 있으므로 혈액, 두발및 발톱을 연 폭로평가의 상호보완, 혹은 대체시료로써 이용의 가능성이 있다고 생각된다.

• 대한기계학회논문집B
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• 제29권2호
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• pp.232-238
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• 2005

The 'Mixing Index($D_I$)' is used as a conventional guidance measuring the degree of mixing for multiphase flows. For the case when insoluble solutions flow in a passive micromixer, a new method to calculate $D_I$ is proposed. The 'Vortex Index(${\Omega}_I$)' is suggested and formulated. We infer that ${\Omega}_I$ relates to the degree of chaotic advection. Various arbitrary shaped microchannels were tested to calculate the $D_I\;and\;{\Omega}_I$, and then a simple algebraic equation, $D_I=Aexp(B{\Omega}_I)$, is obtained. This equation may be used instead of the conventional partial differential equation, concentration equation, to estimate the degree of mixing.

• 상하수도학회지
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• 제19권5호
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• pp.619-624
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• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.199-203
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• 2016

An enzyme-free optical method is proposed for estimating high concentrations of glucose in a glucose-lactose mixture, based on a predictive equation that takes advantage of the reflective optical power observed at two discrete wavelengths. Compared to the conventional absorption spectroscopy method based on Beer's Law, which is mainly valid for concentrations below hundreds of mg/dL, the proposed scheme, which relies on reflection signals, can be applied to measure higher glucose concentrations, of even several g/dL in a glucose-lactose mixture. Two probe wavelengths of 1160 and 1300 nm were selected to provide a linear relationship between the reflective power and pure glucose/lactose concentration, where the relevant linear coefficients were derived to complete the predictive equation. Glucose concentrations from 2 to 7 g/dL in a glucose-lactose mixture were efficiently estimated, using the established predictive equation based on monitored reflective powers. The standard error of prediction was 1.17 g/dL.

• Ocean and Polar Research
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• 제29권1호
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• pp.9-31
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• 2007

Most seismic sea waves in the East Sea originate from earthquakes occurring near the Japanese west coast. While the waves propagate in the East Sea, they are deformed by refraction, diffraction and scattering. Though the Boussinesq equation is most applicable for such wave phenomena, it was not used in numerical modelling of seismic sea waves in the East Sea. To examine characteristics of seismic sea waves in the East Sea, numerical models based on the Boussinesq equation are established and used to simulate recent tsunamis. By considering Ursell parameter and Kajiura parameter, it is proved that Boussinesq equation is a proper equation for seismic sea waves in the East Sea. Two models based on the Boussinesq equation and linear wave equation are executed with the same initial conditions and grid size ($1min{\times}1min$), and the results are compared in various respects. The Boussinesq equation model produced better results than the linear model in respect to wave propagation and concentration of wave energy. It is also certified that the Boussinesq equation model can be used for operational purpose if it is optimized. Another Boussinesq equation model whose grid size is $40sec{\times}30sec$ is set up to simulate the 1983 and 1993 tsunamis. As the result of simulation, new propagation charts of 2 seismic sea waves focused on the Korean east coast are proposed. Even though the 1983 and 1993 tsunamis started at different areas, the propagation paths near the Korean east coast are similar and they can be distinguished into 4 paths. Among these, total energy and propagating time of the waves passing over North Korea Plateau(NKP) and South Korea Plateau(SKP) determine wave height at the Korean east coast. In case of the 1993 tsunami, the wave passing over NKP has more energy than the wave over SKP. In case of the 1983 tsunami, the huge energy of the wave passing over SKP brought about great maximum wave heights at Mukho and Imwon. The Boussinesq equation model established in this study is more useful for simulation of seismic sea waves near the Korean east coast than it is the Japanese coast. To improve understanding of seismic sea waves in shallow water, a coastal area model based on the Boussinesq equation is also required.

• 한국물환경학회지
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• 제22권1호
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• pp.166-171
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• 2006

The objectives of the present paper were to investigate the concentration of total coliform in wastewater effluents and the effect of water chemical and physical characters in it. The most correlated parameter with total coliform was COD. It means that the wastewater treatment efficient effects on total coliform concentration. And we developed predictive model for the total coliform concentration. The estimated parameters for model were COD, temperature, nitrite, chloride, Mn and regression model equation was determined; log (Total Coli.) = 1.861+0.065[COD]+0.038[temperature]-0.0004[$Cl^-$]+3.697[Mn]-0.32 [$NO_2-N$] The developed model provided very strong correlation ($R^2:0.82$) between total coliform and regression equation. The parameters having high sensitivity were COD and temperature. So the study indicated that if the temperature and COD of wastewater effluent were known, we would estimate the concentration of total coliform and decide the most effective usage of chlorine.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.6-7
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• 2019

Asbestos has been widely used for construction materials due to its sound absorption and insulation properties. Despite the announcement that asbestos may cause cancer, asbestos demolition work has become more active. Asbestos was scattered by demolition work and the government started to regulate it. This study was started to predict the scattering asbestos concentration according to the research that it can cause cancer even if the concentration of asbestos meets legal standards. Therefore, in this paper, a regression analysis was conducted to derive a predictive equation after collecting and arranging the variables affecting scattering asbestos. As well as, artificial neural network analysis was used to make a more suitable prediction model.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권3호
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• pp.65-72
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• 2013

Adsorption of melamine was examined using columns packed with granular activated carbon (GAC). Raw GAC was sieved with 20, 40, 60 and 80 mesh to determine the influence of adsorbent particle size on reaction and diffusion. The mass ratio of the adsorption capacity of GAC for melamine ranged from 9.19 to 11.06%, and adsorption rates increased with decreasing particle size within this range. Rate constants between 3.295 ~ 4.799 $min^{-1}$ were obtained using a pseudofirst-order equation that was used to determine adsorption kinetics. A surface diffusion model was adapted to take into account the unsteady-state equation of a spherical adsorbent by converting the surface concentration from a constant to a variable governed by a dispersion equation. The calculated values were fit with the experimental results by using the diffusion coefficients as regression parameters. The modified equation exhibited a more precise agreement with respect to the sum of the absolute error (SAE).

• 공업화학
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• 제29권6호
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• pp.789-798
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• 2018

고분자전해질 연료전지(PEMFC)의 성능을 예측할 수 있는 empirical equation의 역할이 중요하게 대두되고 있다. 본 연구에서는 polarization curve에서 activation loss, ohmic loss, mass transfer loss 영역을 분리하였고, 현재까지 개발된 model 중 Kim의 model과 Hao의 model을 선정하여 각 영역의 fitting을 시행하였다. 온도, 압력, 산소 농도 및 막 두께를 운전변수로 설정하여 조건 변화에 대한 각 loss의 변화를 비교하였다. 기존 model은 전반적으로 좋은 fitting 정확도를 보였지만, 분리된 loss 영역에서는 부정확한 fitting 결과를 보이기도 하였다. 연료전지 성능 예측의 정확도를 개선하기 위하여 converge coefficient를 도입한 새로운 model을 제안하였다. 본 연구에서 제안한 model을 연료전지 성능 예측에 적용한 경우에 신뢰도 평가에서 개선된 결과를 얻을 수 있었다.