• Proceedings of the KSR Conference
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• 2006.11b
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• pp.387-391
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• 2006

Insight into behaviour of pedestrians as well as tools to assess passenger flow conditions are important in for instance planning and geometric design of railway station under regular and safety-critical circumstances. Algorithm for passenger flow analysis based on DEM(Discrete Element Method) is newly developed. There are lots of similarity between particle-laden two phase flow and passenger flow. The velocity component of 1st phase corresponds to the unit vector of calculation cell, each particle to passenger, volume fraction to population density and the particle velocity to the walking velocity, etc. And, the walking velocity of passenger is also represented by the function of population density. Key algorithms are developed to determine the position of passenger, population density and numbering to each passenger. To verify the effectiveness of new algorithm, passenger flow analysis for the basic models of railway station is conducted.

• Journal of the Korean Regional Science Association
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• v.35 no.4
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• pp.33-45
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• 2019

Due to the global low growth trend, urban shrinkage is a major issue of urban policy in major industrialized countries. According to the research results of the KRIHS(Korea Research Institute for Human Settlements, 2016), 23 out of 77 cities in Korea were diagnosed as continuous or temporary shrinking cities. However, the criterion for diagnosing shrinking cities remain on the simple demographic side, and the spatial shrinkage pattern of the city is not considered. Therefore, this study diagnosed urban shrinkage phenomenon considering the characteristics of Yeong-ju, a poly-centric city, by using the population gradient curve, which is one of the urban spatial structure analysis methods. As a result of the diagnosis, Yeong-ju turned out to be a shrinking city with the population density and the slope of population density increasing. In the case of area of Dong, a sprawl phenomenon in which the population density of the CBD and the slope of the population density were decreased was shown. And in the case of Punggi-eup, a simple shrinkage phenomenon in which only the population density of the CBD was decreased was shown. The results show that even within a city, the pattern of spatial change can be different for each centers. In the case of a city with a poly-centric structure, the implications for the individual diagnosis of not only the entire city but also the detailed area were drawn.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.83-92
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• 2005

We try to evaluate the stock level of Korean transportation infrastructure comparing Korean SOC stock level with those of OECD countries. In order to do so, we work on indices to show the transportation infrastructure stock levels of various countries. Among several indices, we select the effective road-extension rate per population density and the effective railroad-extension rate per population density corresponding to road and railroad. We compare Korean road and railroad stock levels with those of OECD countries, to make use of the effective road-extension rate per population density and effective railroad-extension rate per population density. We choose the Britain, Greece, Portugal, and Sweden to compare Korea because their sizes of population and territory are similar to those of Korea. Using International comparison, we arrive at the conclusion that Korean road and railroad stock levels are 63.4% and 53.2% of those of four countries respectively. In addition, we estimate the target level of road and railroad stocks and compute the target level of investments in road and railroad based on the result.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.57-69
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• 2011

This study examined the relationship between Phragmites australis' growth and sediment properties at mud tidal flat of Donggum-ri, Gilsang-myeon, Gangwha-gun, Incheon city. Field survey was carried out from May, 2010 to October, 2010. Water content, soil texture, electric conductivity and water table depth for sediment, density, height, dry weight and flowering for P. australis were examined at several plots from the starting point (the coastal embankment) to the end point of the two populations. The result was as follows. Firstly, the water table increased along distance from the embankment at one line (N-line) but was similar at the other line (S-line) in a P. asustralis population. Water tables were higher out of than within a P. australis population at two populations. Secondary, in N-line, the height and dry weight of P. australis decreased along the distance from embankment but, in S-line, those were similar in its population. P. australis' growth was dependent on electric conductivity at lower layer (water table level) rather than upper one (the surface). Thirdly, density of P. australis changed during growing season and was similar in a population, except for the end point of patch. In summary, the growth and distribution of P. australis were dependent on salt content of tidal flat's sediment (water table level) and this was affected by fresh water of the inland.

• Korean journal of applied entomology
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• v.31 no.2
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• pp.133-138
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• 1992

This study investigated species, damage to fruits and population density of Pseudococcidae on pear in Naju, Chonnam province from 1990 to 1991. Three species, Planococcus kraunhiae, Pseudococcus comstocki and Crisicoccus matsumotoi, were identified. Of them P. kraunhiae was most abundant as 80.6%. Rate of fruit damages was greatest in var. Poongsoo as 39.7% but locations of field did not affect the rates. Degree of damages on Singo(late var.), Poongsoo (midseason var.) and Haengsoo(early var.) was 21.2, 18.2 and 13.3%, respectively. Population density of scales within paper bag of fruits began to increase from mid-June and showed the first at mid-July, the second at mid-August and third peak at early October. Rate of fruit damages was 48% at the first peak and 50.6% at 7 days after the second peak. Density increased from early October again but migration was not active presumably because of cold weather.

• Korean Journal of Organic Agriculture
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• v.6 no.2
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• pp.75-80
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• 1998

Organically cultured rice fields were surveyed to compare the population density and the structure of microarthropod communities between chemically controlled and un-controlled fields. In rice fields, microarthropod communities were also compared among four treatments based on different input of fertilzer : 1)No fertilizer, 2)Chemical fertilizer(N-P2O5-K2O = 11 - 7 - 8 kg/10a, 3) Compost (5,000kg/10a), 4) Compost com-plemented with chemical N. Richness index of microarthropod communities in rice fields was greater in the chemically uncontrolled field than controlled field. Within field. the compost plot had greater value of richness index for microarthopod commuities than the non-fertilizer polt. A total of 9 aquatic insects species were identified in the water of organic farming rice field the population density was found to be higher in the compost plot than the other plot. The population of insect pests was found to be high in the late stage of plant whereas the population of insects was high in the early stage of rice plant.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.877-884
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• 2011

Although peak loading coefficient is one of critical design factors for sewer works, its detailed affecting factors were not analyzed because of limited data availability. This study analyzed the affecting factors on peak loading coefficient with plenty data obtained from several newly constructed sewer works. Simple and multiple regression analysis methods were adopted to analyze the relationships of each variable with or without data filtering. Drainage population, drainage area, population density, and daily sewage flow per person showed very weak relationships under diverse characteristics of cities. However, daily sewage flow per person showed stronger relationships with peak loading when daily sewage flow per person was splitted into two ranges. Population density (i.e., drainage population divided by drainage area) and daily sewage flow per person considerably were related with peak loading coefficient when daily sewage flow per person is less than about 400 Lpcd.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.702-707
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• 1999

A percoll density gradient technique was developed for producing high quality turkey semen and improving the fertility by removing deleterious cellular components, including spermiophages, bacteria, abnormal or dead spermatozoa, and other cellular debris. The combination of three different percoll densities, 1.05, 1.07, and 1.08 showed the best resolution and was selected to prepare a discontinuous percoll density gradient to obtain healthy spermatozoa from semen smples. Bacteria, spermiophages, and abnormal or dead spermatozoa were detected from the density range from 1.05, 1.05 to 1.07, and 1.07 to 1.08, respectively. Healthy spermatozoa were collected from the density greater than 1.08. Spermatozoa obtained from percoll density gradient centrifugation showed better sperm motility than those from unprocessed pooled semen. Bacteria including Escherichia coli, Staphylococcus aureus, and Proteus spp., were predominant contaminants in turkey semen, and the numbers of cells were approximately $5{\times}10^5$ to $1{\times}10^9cfu/ml$. The overall fertility rates in hens inseminated with processed percoll density gradient were higher than those in hens with unprocessed semen especially for unhealthy sperm. In conclusion, semen quality can be improved by percoll density gradient centrifugation, which augmented the fertility of turkey breeders.

• The Journal of the Acoustical Society of Korea
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• v.24 no.8
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• pp.447-453
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• 2005

Laboratory measurements were performed in a uni-algae medium Cochlodinium polykrikoides (Phytoplankton, dinoflagellates) using an Underwater Ultrasound $(5\~15\;MHz)$ to study Characteristics of Acoustic Backscattering of Harmful algae. In an effort to detect the harmful algal scatterers with population density of less than 300 cells/ml that corresponds to the precaution stage of red tide, backscattered signals from various scatterer-density samples were obtained and analyzed. Correlations between volume backscattering strength (Sv) and population density (cells/ml) of scatterers in the medium have been investigated. Comparison of Volume Backscattering Strengths calculated with the fluid-sphere model [1] and the measured values showed an agreement.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.2
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• pp.120-131
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• 2009

This study measured the centripetal force and effective scope of the population spread from urban center and subcenters in order to diagnose the urban spatial structure of the formation of a multicentric city structure in Busan. The study analyzed the variability of the determination coefficient value (R square) with a negative exponential function derived from the population density model by extending the circular region into 5-km units. The aim of this study was to measure changes in the effective scope of the population centripetal force of the urban center and subcenter in 5-year intervals from 1995 to 2005 using census data. The explanatory adequacy of the population density function was examined with the bias of the function to calculate the distance error between the real location of the urban center and the optimal location, according to the population density function. To summarize the results, the value for the area of Jungangdong showed a continuous reduction, whereas Seomyeon (Bujeondong) maintained explanatory adequacy without a large change. As a whole, Busan was in the process of continuous diversification, in spite of its reduced population. Therefore, it appears necessary to strengthen the function of the urban center and subcenter and to supply adequate dwelling zones close to downtown to form a more efficient urban spatial structure. The results of the present study will be utilized as basic data for the formulation of a political approach to the efficient reorganization of spatial structure by correlating concrete spatial information with the population variability of Busan's urban center and subcenter.