• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.5-13
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• 2002

고도의 산업화성장에 따라 도시의 기능이 지역간의 완전분리가 아닌 경제적 사회적 상호 연관성이 점점 증가하고 그 내용도 복잡하고 다양해짐에 따라 이에 대한 체계적인 분석이 필요하게 되었으며, 그에 대한 연구 또한 활발히 진행되고 있다. 그러나 기존에 연구에서 제시하고 있는 각 지역단위별로 취업자수에 대한 고용자수 비율 또는 출근통행의 유출량에 대한 유입량 비율 등의 단순지표를 이용한 지역간의 경제적 의존성을 설명하는 데는 한계가 있다고 할 수 있다. 따라서 본 연구는 지역간의 경제적 연관관계 즉 경제적 의존성을 복합적이고 표준화 할 수 있는 계량치로 추정하기 위해 두 변수 집합간의 연관성을 추정하는데 매우 유용한 분석기법인 정준상관분석 기법을 이용하여 추정하고자 하였다. 이에 수도권 72개존의 출근통행자료을 이용하여 지역간의 경제적 의존성을 측정하였으며, 각 존들로 구성된 지역간의 정준상관계수 및 각 존들의 정준가 중계수를 통해 통계적으로 정산되어진 표준화된 계수를 산출하였다. 그 결과 대존의 경우 경기도와 인천시는 각각 0.9753. 0.2968 정도의 서울에 대한 경제적 의존정도를 보이는 것으로 나타나 서울에 대한 경기도의 경제적 의존성이 높은 것으로 나타났으며, 산출된 정준가중계수를 살펴보면 분당구와 서울시의 중구는 서울에 대한 경기도의 경제적 의존성에 가장 높은 영향을 미친 것으로 나타났으며, 또한 중존에 해당되는 인천의 3개 권역, 경기의 16개 권역의 서울 5개 권역에 대한 경제적 의존성도 분석되었다.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.405-410
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• 1983

Bei Verteilungskoeffizient-Werten von 1,3 bis 325 wurde eine lineare Abhangigkeit sowohol der Halbwertsbreite als auch des Elutionsmaximums vom Verteilungskoeffizient gefunden. Die Elutionsversuche an Natrium und Casium haben gezeigt, $da\beta$ eine lineare Abhangigkeit zwischen Sauleulange und Elutionsmaximum besteht. Dieses Verhalten konnte bei 30cm bis 540cm Saulenlange bestatigt werden. Es ist keine lineare Abhangigkeit zwischen Saulenlange und Halbwertsbreit. Es ist zu sehen, $da\beta$ die Halbwertsbreite mit $gro{\beta}er$ wendendem Saulenlange schwach abfallen. Das starkere Abbiegung der Halbwertsbreite bei wachsender Saulenlange fur Substanzen mit geringeren Verteilungskoeffizientunterschied weist auf eine deutliche Verbesserung der Trennung bei Verwendung von $gro{\beta}en$ Saulenlangen hin.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.15-24
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• 2007

This paper will present a simple approach (or predicting layer deformation of unbound pavement materials with stress-dependent material properties. The approach is based on an uncoupled formulation in which the resilient and deformation response of unbound materials are considered separately. As a result, an uncoupled approach incorporating a resilient stiffness and Poisson's ratio model is able to simulate field measured deformation in pavement foundations. In addition, a sensitivity analysis is conducted to identify the significant factors in the stress-dependent modulus and Poison's ratio model. The predicted trends of deformation from this analysis are presented and discussed.

• Composites Research
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• v.14 no.3
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• pp.69-76
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• 2001

This paper proposes a double cantilever sandwich-beam method fur evaluating the frequency dependence of dynamic characteristics of rubbers. The flexural vibration of a double cantilever sandwich-beam specimen with an inserted rubber layer was studied using a finite element simulation in combination with the sine-sweep test. Quadratic relationships of dynamic elastic modulus and material loss factor of rubbers with frequency were suggested employing the least square error method.

• Journal of the Korea Concrete Institute
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• v.25 no.2
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• pp.145-153
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• 2013

Recently, accelerated chloride diffusion coefficients are used for an evaluation of chloride behavior. Similar as apparent diffusion coefficients, accelerated diffusion coefficients decrease with time. In this study, decrease in diffusion coefficient with time is simulated with porosity. Utilizing DUCOM-program, porosities from 15 mix proportions are obtained and diffusion coefficients are modelled with regression analysis of porosity for 270 days. Considering non-linear binding capacity which means the relation between free and bound chloride ion, chloride behavior in high performance concrete is evaluated. Through utilizing the previous test results for concrete under chlorides for 180 days, the applicability of the proposed technique is verified. The proposed technique is evaluated to reasonably predict the chloride behavior in concrete with various w/c (water to cement) ratios and mineral admixtures (GGBFS and FA). It is also shown that decrease in chloride diffusion should be considered for chloride prediction in concrete with mineral admixture since it has very clear decrease in diffusivity with time.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.83-91
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• 2015

With varying conditions of concrete surface, induced chloride contents are changed and this is a key parameter for steel corrosion and service life in RC (Reinforced Concrete) structures. Many surface enhancement techniques using impregnation have been developed, however the evaluation techniques for chloride behavior through doubly layered media and time-dependent diffusion are rarely proposed. This paper presents an analysis technique considering double-layer concrete and time-dependent diffusion behavior, and the results are compared with those from the previous test results through reverse analysis. The chloride profiles from the surface-impregnated concrete exposed to atmospheric, tidal, submerged zone for 2 years are adopted. Furthermore surface chloride contents and diffusion coefficients are obtained, and are compared with those from Life365. Through consideration of time effect, the relative error decreases from 0.28 to 0.20 in atmospheric, 0.29 to 0.11 in tidal, and 0.54 to 0.40 in submerged zone, respectively, which shows more reasonable results. Utilizing the diffusion coefficients from Life365, relative errors increases and it needs deeper penetration depth (e) and lower diffusion coefficient ratio ($D_1/D_2$) due to higher diffusion coefficient.

• Proceedings of the KSEEG Conference
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• 2000.04b
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• pp.235-236
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• 2000

• Nuclear Engineering and Technology
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• v.16 no.4
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• pp.195-201
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• 1984

A state-of-the-art mechanistic model has been developed to accurately predict the void fraction in the subcooled boiling region having axial nonuniform heat flux. In this study, the void-dependent drift-flux parameters of the Lahey/Ohkawa model were introduced and the mass flux-dependent condensation coefficient were determined by fitting with the experimental data. This model was tested against several experimental data sets to verify its accuracy. Finally the comparison between the predicted void fraction profiles with this model and the profile-fit model for the hot assembly of Kori-Unit 1, Cycle 1 has been performed. It is conclusive that the results show the good agreement between the measured and predicted void fractions, and the profile-fit model has been found to underestimate the void fraction in the subcooled boiling region.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.460-464
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• 2000

As device dimensions are lastly scaled down, impact ionization(I.I.) events are very important to analyze hot carrier transport in high energy region, and the exact model of impact ionization is demanded on device simulation. We calculate full band model by empirical pseudopotential method and the impact ionization rate is derived from modified Keldysh formula. We calculate impact ionization coefficients by full band Monte Carlo simulator to investigate temperature-and field-dependent characteristics of impact ionization for GaAs. Resultly impact ionization coefficients are In good agreement with experimental values at 300k. We know energy is increasing along increasing the field. while energy is decreasing along increasing the temperature since the phonon scattering rates for omission mode are very high at high temperature. The logarithmic fitting function of impact ionization coefficients is described as a second orders function for temperature and field. The residuals of the logarithmic fitting function are mostly within 5%. We know, therefore, logarithm of impact ionization coefficients has quadratic dependence on temperature and field, and we can save time of calculating the temperature- and field-dependent impact ionization coefficients.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.8-15
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• 2019

When RC(Reinforced Concrete) structures are exposed to harsh environment, deterioration phenomenon occurs, and the corrosion in rebar due to chloride intrusion is known as representative deterioration, so called chloride attack. In this paper, chloride resistance performance of 2 years aged concrete is evaluated considering 3 levels of water to binder ratio(0.37, 0.42, and 0.47) and 2 levels of substitution ratio of fly ash(0% and 30%). Accelerated chloride diffusion coefficient tests referred to Tang's method, total passed charge tests referred to ASTM C 1202, and compressive strength tests referred to KS F 2405 are performed. With adaptation of the previous test results and the results from this study, time-dependent chloride diffusion characteristics are analyzed for each concrete. The FA(Fly Ash) concrete has higher chloride resistance performance than OPC(Ordinary Portland Cement) concrete. According to the evaluation standard of ASTM C 1202, the FA concrete has "Moderate" grade after 49 days while OPC concrete does "Moderate" grade after 365 days. As the results of time-parameter for chloride diffusion, OPC concrete and FA concrete show the decreasing behavior of time-parameters with increasing water to binder ratio. Also, FA concrete has 1.57~2.74 times of time-parameter than OPC concrete. That's cause is thought that the time-parameter indicates the gradient of decreasing of diffusion coefficient. FA concrete has higher time-parameters than OPC concrete by pozzolanic reaction of FA.