• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.43-51
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• 2004

In this study, gas permeation and separation characteristics of $CO_2$ and $N_2$ on nano-porous TPABr(Tetrapropylammoniumbromide) templating silica/alumina composite membrane were studied by using GMS (Generalized Maxwell Stefan) model. Since the transport mechanisms of meso-porous alumina support are Knudsen diffusion and viscous diffusion(or poiseulle flow), they can be identified by DGM (dusty gas model). The transport mechanism of TPABr templating silica layer, which would contribute mainly to the separation of $N_2/CO_2$ mixture, showed surface diffusion rather than pore diffusion. Therefore, the oermeationjseparation mechanisms in multi-component suface diffusion were successfully analyzed by the GMS model. In the separation of $N_2/CO_2$ mixture using the composite membrane, $CO_2$, the strongadsorbate, was permeated through the membrane more than Na due to the pore-blocking phenomena of $CO_2$ by adsorption isotherm and solace diffusion.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.914-918
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• 1992

The preferential transport phenomena of neutral cation-anion moieties in neutral macrocycle-facilitated emulsion liquid membrane were described in this study. Emulsion membrane systems consisting of (1) aqueous source phase containing 0.001M $M(NO_3)_2$ (M = $Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Sr^{2+}$, $Cd^{2+}$, $Pb^{2+}$) (2) a toluene membrane containing 0.02M ligand (DB$N_3O_2$, DB18C6) and the surfactant span 80 (sorbitan mono oleate) (3% v/v) and (3) aqueous receiving phase containing $Na_2S_2O_3$ or $NaNO_3$ were studied with respect to the disappearence of metal ions from the source phase as a function of time. Cation transport rates for various two component equimolar mixture of metal ions were determinded. $Cd^{2+}$ was transported higher rates than the other $M^{2+}$ in the mixture solution.

• Journal of the Korean Society for Railway
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• v.11 no.5
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• pp.455-464
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• 2008

This paper examines the situation and tasks of competitive systems of EU transport market focusing on railways. Recently, the EU transport market has changed radically, thanks to an increasingly competitive rail market. The European Commission has stimulated the creation of a competitive environment that will enhance the position of rail. Some scholars have insisted that the rail market is more monopolistic than competitive. However, the case of UK rail privatization suggests this is not the case. Moreover, some countries have a rail market that is more competitive. We draw on a wide range of sources including statistics and analyses of recent phenomena. These demonstrate the emergence of competitive markets in EU rail and the difficulty of developing a competitive market. With regard to the adoption of the competitive market, we examine three things. First, we observe recent cases and trends in competitive markets. Second, we compare the result of competitive markets and non-competitive markets within EU nations. Third, we demonstrate factors of formation of competitive markets and the possible expansion. We identified differences within open market policies amongst EU nations. Although a competitive EU rail market may have some difficulties, it will steadily begin to overcome technological differences and a lack of funds, because EU countries have a common goal, which is to develop the railways, solving, wherever possible both environmental and energy problems. Through this analysis, we found that the free market in EU rail will be extended to deliver efficiency and quality service.

• Journal of the Korean Geographical Society
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• v.31 no.1
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• pp.19-37
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• 1996

This paper aims at examining the regional difference of changes in the business organization of retailing in the Seoul metropolitan areas, as an attempt to understand regional structure of retailing within metropolitan areas showing the trend of suburbanization. On the national level, retail sales have concentrated on the large metropolitan areas, especially on the Seoul metropolitan area, with the concentration of population and income. Within metropolitan areas, the suburbanization of retailing has made the larger structure of retail and multi-store retail appeared. In order to confirm such phenomenon, this paper is to analyze and to compare the industrial composition of retailing using industry data of 1979 and 1991. And this paper is to analyze the regional changes in the characteristics of business organization of retailing, with the index including the percentages of establishments with less than under four employees, juridical establishments, employees of ordinary times, and the annual sales per establishment of detailing. The characteristics of business organization of retailing in analyzed by principal components analysis, and the types with component in each district (city, county, ward) is analyzed by cluster analysis(Ward method). The data of 1979 were obtained from the statistics in the Census of Wholesale and Retail Trade published by the National Bureau of Statistics of Economic Planning Board, and that of 1991 were obtained from the statistics in the Report on Establishment Census (Vol.3 Wholesale and Retail Trade) published by the National Statistics Office. The following are resultant findings. 1. In Seoul metropolitan area, changes in the industrial composition of retailing with annual sales from, 1979 to 1991 show very higher composition rates of 'general merchandise stores' and 'retailing of personal transport equipment and gasoline service stations', but comparatively lower composition rates of 'retailing of food, beverages and tobacco', 'retailing of textiles, clothing, footwear and apparel accessaries', 'general retail trade, n.e.c.',and 'retailing of household fuel'. 2. The characteristics of business organization of retailing in Seoul metropolitan area presents the prevailence of small, personal business organization and especially larger employees of ordinary times. 3. Business components of retailing by principal components analysis in Seoul metropolitan area are follows: 1 All retaining industries are larger business scale. 2. Larger business take the 'retailing of taxtiles, clothing, footwear and apparel accessories', 'retailing of furniture, home furnishing and equipment', and 'retailing of jewellery and watches' is main characteristic legal organization and employees of ordinary times. 4. Types changes in business organization of retailing in Seoul metropolitan area represent legal organization and employees of ordinary times taking the 'retailing of textiles, clothing, footwear and apparel accessories', 'retailing of furniture, home furnishing and equipment',and 'retailing of jewellery and equipment', and 'retailing of jewellery and watches', and legal organization taking 'general retail trade, n.e.c.' in 1979. All retailing industries are changed into larger business scale, in 1991. These phenomena of business changes appeared southeastern regions in Kyunggi-do(province). And larger business scale taking the 'retailing of textiles, clothing, footwear and apparel accessories', 'retailing of jewellery and watches', and 'general retail trade, n.e.c.; are appeared in the legal organization in 1979. 'Retailing of personal transport equipment and gasoline service stations' are appeared in employees of ordinary times in 1991. These phenomena of business changes in appeared in eastern and northern regions in Kyunggi-do. 5. Changes in the business organization of retailing in Seoul metropolitan area is appeared in legal organization and employees of ordinary times for some industries in 1979, larger business scale of retailing and employees of ordinary times in 'retailing of personal transport equipment and gasoline service stations' are the characteristics in 1991.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.140-147
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• 2005

We investigated the interactions between coastal waters of the Yeongil Bay, Korea, and oceanic waters of the Eastern Sea, as wet 1 as the development mechanism of vertical circulation currents in the bay. The oceanic waters of the bay have an average water temperature of $12.2{\sim}18.4^{\circ}C$ and salinity of $33.32{\sim}34.43$ PSU. Results of spectral analysis have shown that the period of revolution between oceanic and coastal waters is about 0.84-0.91 years in the surface waters and 1.84 years in the bottom layer. The wind direction in the bay shifts between SW and NE, with the main wind direction being SW during the winter period, and water mass movement is influenced by such seasonal variations in wind direction. Vertical circulation currents in the bay are structured by two phenomena: the surface riverine outflow layer from the Hyeong-san River into the open sea and the bottom oceanic inflow layer with high-temperature and salinity into the bay. These phenomena start the spring when the water mass is stable and become stronger in the summer when the surface cold water develops over a 10-day period. Consequently, tidal currents have little influence in the bay; rather, these vertical and horizontal circulation currents play an important role in the transport of the pollutant load from the inner bay to the open sea.

• Journal of Korea Water Resources Association
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• v.43 no.10
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• pp.911-920
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• 2010

The closed water bodies, such as reservoirs and lakes, could be contaminated by an inflow of pollutants in the upstream as well as a stratification caused by seasonal natural phenomena. The vertical circulation particularly plays an important role in reduction of environmental pollutants. The factors of the vertical circulation are the temperature, wind, thermal diffusivity and sunlight. The wind is probably the most significant factor among them. Thus, it is necessary to describe the validation and application of a three-dimensional numerical model of wind-induced circulation in a thermally stratified flow. In this paper, a three-dimensional numerical model for the thermally stratified flows is presented. The model is conducted in three steps to calculate the velocity components from the momentum equations in x- and y- axis directions, the elevations from the free surface equation and the temperature from the scalar transport equation. Numerical predictions are compared with available analytical solutions for the sloshing free surface movement in a rectangular basin. The numerical results generally show a reasonable agreement with analytical solutions. And the model is applied to the circulation for the wind induced flow in a thermally stratification. Consequently, the developed model is validated by two verifications and phenomena of the internal flow.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.639-650
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• 2022

In areas where large-scale sediment transport occurs, it is important to apply appropriate countermeasure method because the phenomenon tends to accelerate by time duration. Among the various countermeasure methods applied so far, beach nourishment needs to be reviewed as an erosion prevention measure because the erosion pattern is mitigated and environmentally friendly depending on the particle size. In the case of beach nourishment. a detailed review is required to determine the size, range, etc., of an appropriate particle diameter. In this study, we investigated the characteristics of the related topographic change using the change in the particle size of nourishment materials, the application of partial area, and the condition under the coexistence of waves and wind as variables because those factors are hard to be analyzed and interpreted within results and limitation of that the existing numerical models are not able to calculate and result out so that it is required that phenomenon or efforts are reviewed at the same time through physical model experiments, field monitoring and etc. So we attempt to reproduce the tendency of beach erosion and deposition and predict possible phenomena in the future using machine learning techniques for phenomena that it is not able to be interpreted by numerical models. we used the hydraulic experiment results for the training data, and the accuracy of the prediction results according to the change in the training method was simultaneously analyzed. As a result of the study it was found that topographic changes using machine learning tended to be similar to those of previous studies in short-term predictions, but we also found differences in the formation of scour and sandbars.

• Asian Journal of Atmospheric Environment
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• v.7 no.2
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• pp.65-71
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• 2013

Japanese cedar (Cryptomeria japonica) pollinosis is the most popular pollinosis in Japan. It has been reported that Cryptomeria japonica pollen allergenic species are suspended as fine particles in the urban atmosphere. These allergenic fine particles are responsible for inducing asthma by breaking into the lower respiratory tract. It has also been found that pollinosis symptoms on the sufferers appear mainly at night-time by the results from epidemiological studies. However, the exact reason for these phenomena is not yet clarified. In this study, the diurnal and nocturnal behaviours of Cryptomeria japonica pollen grains and their allergenic species in the urban area of Saitama city of Kanto Plain were investigated. Airborne pollen grains and allergenic Cry j 1 concentrations in total suspended particulate matter (TSP) were investigated at two sampling sites, a heavy traffic road (roadside site) and at the balcony of the $10^{th}$ floor of the Building of Research and Project of Saitama University (general urban site). The latter sampling site where located about 300 m away from the roadside site was used as a general urban site unaffected by automobile traffic. The airborne pollen counts were measured with a real-time pollen monitor. Cry j 1 particles were collected with two high volume air samplers, and these concentrations were measured by surface plasmon resonance method with a Biacore J system. The diurnal variation of the airborne pollen counts was similar to the trends of temperature and wind speed during the day-time; whereas its tendency with wind speed trend was not observed during the night-time. Airborne pollen counts were lower with northern wind than with southern wind because the pollen comes from the mountainous areas, and the mountains in the south are closer, about half the distance to the northern mountains. It is suggested that the peaks of airborne pollen counts during night-time in the sampling site occurred by transport of pollen grains released during day-time in the mountainous forest areas, located c.a. 100 km away from the sampling site. On the roadside site the allergenic Cry j 1 concentrations were higher than at the general urban site, nevertheless pollen grains counts were lower. These results suggested that worsening of pollinosis symptoms during night-time in urban area was caused by transport of pollen grains during day-time in the mountainous forest areas. Moreover, pollen allergenic species become different morphology from pollen grain at roadside site, and the subsequent pollen grains re-suspension by automobile traffic.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.1-12
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• 2006

In order to estimate a dynamic origin and destination demand between on and off-ramps in the freeways, a traffic flow theory can be used to calculate a link distribution proportion of traffics moving between them. We have developed a dynamic traffic estimation model based on the three-phase traffic theory (Kerner, 2004), which explains the complexity of traffic phenomena based on phase transitions among free-flow, synchronized flow and moving jam phases, and on their complex nonlinear spatiotemporal features. The developed model explains and estimates traffic congestion in terms of speed breakdown, phase transition and queue propagation. We have estimated the link, on and off-ramp volumes at every time interval by using traffic data collected from vehicle detection systems in Korea freeway sections. The analyzed results show that the developed model describes traffic flows adequately.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.116-126
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• 2016

In this study, lane-wise traffic flow characteristics were analysed on uninterrupted flow using a new notion of "lane-wise travel speed reversal (LTSR)" which is defined as a phenomena that travel speed in the median lane is lower than other lanes. Mathematical formulation was also proposed to calculate the strength of LTSR. The experiment road site is Seoul Outer Ring Expressway (Jayuro-IC~Jangsoo-IC), and travel trajectories for each four lane were collected for weekdays (Mon. through Fri.) during morning peak. Comparing lane-wise travel speeds for entire test road section, no LTSR was observed, meaning that the travel speed in the median lane is the fastest, followed by 2nd, 3rd, and 4th lane as in order. Howerver, the result of microscopic analysis using 100-meter discrete road section based data shows that LTSR occurs many times. Especially the strength of LTSR is higher in congestion area and freeway merge and diverge segment. It is expected that these results could be used as a fundamental data when establishing lane-by-lane traffic operation strategy and developing lane-wise traffic information collection and dissemination technology.