• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.109-121
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• 2007

In this study, an imputation model using circular probability distribution was developed in order to overcome problems of missing data from a traffic survey. The existing ad-hoc or heuristic, model-based and algorithm-based imputation techniques were reviewed through previous studies, and then their limitations for imputing missing traffic volume data were revealed. The statistical computing language 'R' was employed for model construction, and a mixture of von Mises probability distribution, which is classified as symmetric, and unimodal circular probability were finally fitted on the basis of traffic volume data at survey stations in urban and rural areas, respectively. The circular probability distribution model largely proved to outperform a dummy variable regression model in regards to various evaluation conditions. It turned out that circular probability distribution models depict circularity of hourly volumes well and are very cost-effective and robust to changes in missing mechanisms.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.680-685
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• 2012

Ceramic femoral heads are now widely used in Total Hip Replacement (THR). Due to their high biocompatibility and low ductility, ceramic femoral heads are considered to be suitable for young and active patients. However, as in testing the mechanical stability of the femoral head, the conventional proof test (standard ISO 7206-10) has its limit of showing axisymmetric stress distribution on the contact surface, while non-uniformed stress distribution is expected after THR. Since non-uniformed stress distribution can result in the increased probability of ceramic femoral head fracture, it is considerable to evaluate the stress distribution in vivo-like conditions. Therefore, this study simulated the ceramic femoral heads under in vivo-like conditions using finite element method. The maximum stress decreased when increasing the size of the femoral head and stress distribution was concentrated on superior contact surface of the taper region.

• Journal of Korea Water Resources Association
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• v.45 no.6
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• pp.531-544
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• 2012

This study suggested the parameter estimation method for given rainfall events to be properly expressed by the beta distribution. For this purpose, this study compared the characteristics of probability density function with the parameter proposed considering the cases with and without addition to the rainfall peak, and the cases of using the real hyetograph and the rearranged hyetograph about the rainfall peak. As an example, this study analyzed the independent rainfall events at Seoul in 2010 and the annual maximum independent rainfall events from 1961 to 2010. The results derived are as follows. First, this study confirmed the necessity of additional consideration on rainfall peak to mimic the real hyetograph of rainfall events by the beta distribution. Second, this study confirmed the case of using rearranged hyetograph about the rainfall peak derived a better beta distribution to well mimic the characteristics of real rainfall than the case using the real hyetograph.

• The Korean Journal of Applied Statistics
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• v.29 no.5
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• pp.987-998
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• 2016

Auto insurance is an insurance product that requires the proper application of pricing techniques due to intense market competition and the rate regulations of financial authorities. Especially, population change according to aging and rating faction segmentation mainly affect the pricing process. This study suggests a pricing optimization methodology through the proper estimation of age factors. To properly estimate the future distribution of age factor, age change, renewal and conversion of customers are considered as main effects for the optimization of estimation and application. The properness and effectiveness for the suggested method will be proved by a comparison of results applied (one for current distribution and the other for future distribution) at the off-balance process. This study suggests an appropriate risk estimation methodology based on optimization that uses the proper estimation of future distribution to protect from the over or under estimation of risk.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.1
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• pp.38-43
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• 1998

This study examined root growth and distribution under the direct seeding of rice cultivars developed in Korea, Japan, and the U.S. Cultivars from the U.S., especially 'M202' and 'Caloro', had a high ratio of the dry matter partitioning for root and top plant components. Caloro had high root and top growth. 'Koshihikari' from Japan showed the lowest ratio of R/T (root/total dry matter) due to the small amount of root and top plant growth. Most Japanese cultivars except transplanted 'Hatsuboshi' showed low ratio of R/T. Patterns of root distribution for each soil block were recorded by the root box-pin board method. Roots of all cultivars were distributed in blocks A, C, and E in the middle of box, i.e., just below the plant base. Roots of 'Dongjin', M202, and Caloro were distributed deeper than the others. Roots of transplanted Hatsuboshi developed much better than direct seeded Hatsuboshi. Total root weight density was highest in Caloro followed by Dongjin, 'Gancheok', 'Calrose', and the others. The root density of Caloro was twice as much as those of the others except Dongjin. According to cumulative percentages of root distribution on each soil layer, roots of most cultivars were distributed below 20cm. The U.S. cultivars showed vertically well developed root systems as compared to others. A large amount of roots were distributed in the top 15cm of soil layer for Hatsuboshi and Koshinikari, and their root systems appeared to be shallow. In contrast, the rates of root distribution in the top 10cm of soil layer were low for Dongjin, Calrose, and Caloro. These cultivars had relatively deep root systems.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.88-97
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• 2011

For Korean design provisions are not equipped for skewed steel box girder bridges, when American provisions are adopted, load distribution factors different from real behavior are determinated. Furthermore the possibility of over or under estimated bridge design involves. The aim of this study is to provide more rational load distribution factor formulas based on real behavior for shear at obtuse corner of skewed steel box girder bridges. In order to accomplish the aim finite element analysis for a variety of skewed steel box girder bridge structural models is carried out, and each parameters degree of influence on wheel load distribution factors of skewed steel box girder bridges are analyzed. Then multiple regression analysis is fulfilled in order to propose formulas for determinating shear force load distribution factor of skewed steel box girder bridges.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.99-109
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• 2009

In this study, often the spatial distribution of precipitation was analyzed using the quantile with regional frequency analysis and spatial analysis to find out the detail distribution of extreme precipitation for preventing the disaster in the region of Gangwon. The hourly precipitation data of 66 stations in Gangwon were used. As the results of regional frequency analysis, it shows that the generalized logistic (GLO) distribution is the best for the region of Gangwon. As the results of spatial analysis, the quaniles have high vaules nearby Seolakdong, Daegwallyeong and Cheongil as the duration of precipitation increase, and the change of spatial distribution occurs severely according to the duration of precipitation. The spatial characteristics of precipitation appears clearly as the return period of quantile increases. As the results of the spatial distribution of precipitation in Gangwon heavy quantiles usually are appeared in Yongdong, and the spatial distributions of quantile in Yongseo are various according to the duration and the return period of quantile. Therefore, to estimate more accurate quantiles in Gangwon, various geographical and weather conditions are considered additionally for the regional precipitation frequency analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2217-2222
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• 2011

In this paper, the relationship of potential and charge distribution in channel for double gate(DG) MOSFET has been derived from Poisson's equation using Gaussian function. The relationship of subthreshold swing and oxide thickness has been investigated according to variables of doping distribution using Gaussian function, i.e. projected range and standard projected deviation, The analytical potential distribution model has been derived from Poisson's equation, and subthreshold swing has been obtained from this model for the change of oxide thickness. The subthreshold swing has been defined as the derivative of gate voltage to drain current and is theoretically minimum of 60 mS/dec, and very important factor in digital application. Those results of this potential model are compared with those of numerical simulation to verify this model. As a result, since potential model presented in this paper is good agreement with numerical model, the relationship of subthreshold swing and oxide thickness have been analyzed according to the shape of doping distribution.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.598-605
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• 2015

Effective alerts will drastically mitigate the disaster impacts. One way to enhance the effectiveness is to prepare multiple alert distribution channels. In this paper, we propose a new emergency alert distribution system that will solve the weaknesses of the current distribution systems, such as Cell Broadcasting System and T-DMB Automatic Emergency Alert Service. The weaknesses are: the limitation of message length, small portions of terminals that can receive and display the alert signal, and one-way communication service. To solve these problems, we propose an emergency alert distribution system over the Internet with RSS (Rich Site Summary) format. The system also has the capability of adaptive alert filtering according to the receiver characteristics. We analyzed the characteristics of RSS as an alerting format, and draw functional requirements satisfying use case scenarios. We designed the system only with major requirements and verified it on our test bed. Sending richer message contents through various receiving terminals, the system will achieve more effective emergency alert service.

• The Journal of the Korean Society for Microbiology
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• v.19 no.1
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• pp.85-108
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• 1984

In order to study the relationship between resistance of tumor cells to anticancer drugs and immunologic cytotoxicity and their chromosome number, a line of cancer cells (NS-1) was exposed to BCNU and CCNU in vitro. Characteristics of the distribution of chromosome number of the survived cells were then comparatively analyzed. Effect of immune mediated cytotoxicity, i.e. complement and cell-mediated cytotoxicity, on the ploidy characteristics was observed in the same way. NS-1 cells were found to be a population of neoplastic cells of heterogeneity having 5 to 115 chromosomes per cell in metaphase. The majority of the cells were belong to the class of chromosome number 56 to 60 which were considered as the stem cell line. Dramatic changes in the distribution of chromosome number following drug treatment were not observed. However the range of chromosome distribution was slightly changed. Characteristics of chromosomal distribution of drug treated cells were not significantly varied by different doses of drug treated. Changed chromosomal distribution patterns of drug treated cells were reversible, especially the cells having 56 to 60 chromosomes recovered rapidly. Cells having 41-60 and 61-80 chromosomes among cells treated with BCNU and cells with 41-60 chromosomes after CCNU treatment were the major population which regenerated continuously. Following BCNU treatment cells having 61-80 chromosomes were not varied much whereas CCNU treatment affects the population in the same class. Chromosomal aberrations were significantly enhanced by BCNU and CCNU treatment. The frequency of chromosomal aberrations was greater in cells having more than 40 chromosomes compared with that in cells having less than 40 chromosomes. Changes in ploidy characteristics of the cells following complement mediated and cell mediated cytotoxicity were not significant. Therefore it was tentatively concluded that association of numerical distribution pattern of NS-1 cells with the response to the treatment used in this experiment was not recognized.