• Journal of Korean Society of Water and Wastewater
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• v.34 no.4
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• pp.251-258
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• 2020

Sewer deterioration models are needed to forecast the remaining life expectancy of sewer networks by assessing their conditions. In this study, the serious defect (or condition state 3) occurrence probability, at which sewer rehabilitation program should be implemented, was evaluated using four probability distribution functions such as normal, lognormal, exponential, and Weibull distribution. A sample of 252 km of CCTV-inspected sewer pipe data in city Z was collected in the first place. Then the effective data (284 sewer sections of 8.15 km) with reliable information were extracted and classified into 3 groups considering the sub-catchment area, sewer material, and sewer pipe size. Anderson-Darling test was conducted to select the most fitted probability distribution of sewer defect occurrence as Weibull distribution. The shape parameters (β) and scale parameters (η) of Weibull distribution were estimated from the data set of 3 classified groups, including standard errors, 95% confidence intervals, and log-likelihood values. The plot of probability density function and cumulative distribution function were obtained using the estimated parameter values, which could be used to indicate the quantitative level of risk on occurrence of CS3. It was estimated that sewer data group 1, group 2, and group 3 has CS3 occurrence probability exceeding 50% at 13th-year, 11th-year, and 16th-year after the installation, respectively. For every data groups, the time exceeding the CS3 occurrence probability of 90% was also predicted to be 27th- to 30th-year after the installation.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.3
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• pp.149-153
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• 2022

The degree distribution of the plant-pollinator network was identified by analyzing the data in the ecosystem and reproduced by a model of the growing bipartite mutualistic networks. The degree distribution of pollinator shows power law or stretched exponential distribution, while plant usually shows stretched exponential distribution. In the growth model, the plant and the pollinator are selected with probability P_p and P_A=1-P_p, respectively. The number of incoming links for the plant and the pollinator is l_p and l_A, respectively. The probability that the link of the plant selects the pollinator of the existing network given as $A_{k_i}=k^{{\lambda}_A}_i/{\sum}_i\;k^{{\lambda}_A}_i$, and the probability that the pollinator selects the plant is $P_{k_i}=k^{{\lambda}_p}_i/{\sum}_i\;k^{{\lambda}_p}_i$. When the nonlinear growth index is 𝛌_X=1 (X=A or P), the degree distribution follows a power law, and if 0≤𝛌_X<1, the degree distribution follows a stretched exponential distribution. The cumulative degree distributions of plants and pollinators of 14 empirical plant-pollinators included in Interaction Web Database were calculated. A set of parameters (P_A,P_P,l_A,l_P) that reproduces these cumulative degree distributions and a growth index 𝛌_X (X=A or P) were obtained. We found that animal takes very heterogenous connections, whereas plant takes a more flexible connection network.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.228-230
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• 2002

The relative electron density resolution was discussed by the noise power spectrum (NPS) in the heavy ion CT image. The heavy ion beam $\^$12/C accelerated up to 400MeV/u by RIMAC was used in this study. The two-dimensional (2-D) NPS in the CT image was obtained from the one-dimensional (1-D) NPS of the measured residual range distribution of water phantom for single projection, and the noise variance in the CT image was calculated from 2-D NPS. The technique used in the reconstruction was the filtered back-projection method with Shepp-Logan filter. The calculated value suggests the result of our previous works using the density resolution phantom, assuming that the relative electron density resolution is twice the standard deviation. Therefore, the estimation of the noise in CT images by 2-D NPS obtained the measured residual range distribution is the useful method.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6729-6734
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• 2015

Background: To analyze the mortality distribution of nasopharyngeal carcinoma in China from 1991 to 2013, to predict the mortality in the ensuing five years, and to provide evidence for prevention and treatment of nasopharyngeal carcinoma. Materials and Methods: Mortality data for Nasopharyngeal Carcinoma in China from 1991 to 2013 were used to describe its epidemiological characteristics, such as the change of the standardized mortality rate, sex and age differences, urban-rural differences. Trend-surface analysis was used to study the geographical distribution of the mortality. Curve estimation, time series, gray modeling, and joinpoint regression were used to predict the mortality for the ensuing five years in the future. Results: In China, the standardized mortality rate of Nasopharyngeal Carcinoma increased with time from 1996, reaching the peak values of $1.45/10^5$ at the year of 2002, and decreased gradually afterwards. With males being 1.51 times higher than females, and the city had a higher rate than the rural during the past two decades. The mortality rate increased from age 40. Geographical analysis showed the mortality rate increased from middle to southern China. Conclusions: The standardized mortality rate of Nasopharyngeal Carcinoma is falling. The regional disease control for Nasopharyngeal Carcinoma should be focused on Guangdong province of China, and the key targets for prevention and treatment are rural men, especially after the age of 40. The mortality of Nasopharyngeal Carcinoma will decrease in the next five years.

• Progress in Medical Physics
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• v.35 no.2
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• pp.52-57
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• 2024

Purpose: The use of two adjacent radiation beams to treat a lesion that is larger than the maximum field of a machine may lead to higher or lower dose distribution at the junction than expected. Therefore, evaluation of the junction dose is crucial for radiotherapy. Volumetric modulated arc therapy (VMAT) can effectively protect surrounding normal tissues by implementing a complex dose distribution; therefore, two adjacent VMAT fields can effectively treat large lesions. However, VMAT can lead to significant errors in the junction dose between fields if setup errors occur due to its highly complex dose distributions. Methods: In this study, setup errors of ±1, ±3, and ±5 mm were assumed during radiotherapy for treating large lesions in the lower abdomen, and their effects on the treatment dose distribution and target coverage were analyzed using gamma pass rate (GP) and homogeneity index (HI). All studies were performed using a computational simulation method based on our radiation treatment planning software. Results: Consequently, when the setup error was more than ±3 mm, most GP values using a 3%/3-mm criterion decreased by <90%. GP was independent of the direction of the field gap (FG), whereas HI values were relatively more affected by negative values for FG. Conclusions: Therefore, the size and direction of setup errors should be carefully managed when performing dual-isocentric VMATs for large targets.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.651-656
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• 2014

Background: Cervical cancer is the third commonest type of cancer among women in Malaysia. Our aim was to determine the distribution of human papilloma virus (HPV) genotypes in cervical cancer in our multi-ethnic population. Materials and Methods: This was a multicentre study with a total of 280 cases of cervical cancer from 4 referral centres in Malaysia, studied using real-time polymerase chain reaction (qPCR) detection of 12 high risk-HPV genotypes. Results: Overall HPV was detected in 92.5% of cases, in 95.9% of squamous cell carcinomas and 84.3%of adenocarcinomas. The five most prevalent high-risk HPV genotypes were HPV 16 (68.2%), 18 (40%), 58 (10.7%), 33 (10.4%) and 52 (10.4%). Multiple HPV infections were more prevalent (55.7%) than single HPV infections (36.8%). The percentage of HPV positive cases in Chinese, Malays and Indians were 95.5%, 91.9% and 80.0%, respectively. HPV 16 and 18 genotypes were the commonest in all ethnic groups. We found that the percentage of HPV 16 infection was significantly higher in Chinese (75.9%) compared to Malays (63.7%) and Indians (52.0%) (p<0.05), while HPV 18 was significantly higher in Malays (52.6%) compared to Chinese (25.0%) and Indians (28%) (p<0.05). Meanwhile, HPV 33 (17.9%) and 52 (15.2%) were also more commonly detected in the Chinese (p<0.05). Conclusions: This study showed that the distribution of HPV genotype in Malaysia is similar to other Asian countries. Importantly, we found that different ethnic groups in Malaysia have different HPV genotype infection rates, which is a point to consider during the implementation of HPV vaccination.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.2
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• pp.112-120
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• 2010

In this paper time series wave data measured continuously for 24 hours during a storm in Yura Sea Area are used to investigate statistical characteristics of nonlinear waves. The exceedance probability of wave height is compared using the Rayleigh distribution and the Edgeworth-Rayleigh (ER) distribution. Wave data which show stationary state for 10 hours contain 4600 waves approximately. The Gram-Chalier distribution fits the probability of wave elevation better than the Gaussian distribution. The Rayleigh ($H_{rms}$) distribution follows the exceedance probability of wave height in general and predicts the probability of freak waves well. The ER distribution overpredicts the exceedance probability of wave heights and the occurrence of freak waves. If wave data measured for 30 minute period which contains 250 waves are used, the ER distribution can predict the occurrence probability of freak waves well. But it overpredicts the probability of overall wave height If no freak wave occurs, the Rayleigh ($H_{rms}$) distribution agrees well with wave height distribution for the most of wave height ranges. The wave height distribution of freak waves of which height are less than 10 m shows similar tendency compared with freak waves greater than 10 m. The value of $H_{max}/H_{1/3}$ is related to the kurtosis of wave elevation. It seems that there exists threshold value of the kurtosis for the occurrence of freak waves.

• Journal of Distribution Science
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• v.13 no.12
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• pp.85-94
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• 2015

Purpose - The purpose of this paper is to provide a political registration point for analyzing the economic impacts on the national economy from the REITs distribution industry in our country. The REITs distribution industry was introduced in 2001 to accelerate the corporate restructuring process and advance the real estate market. During its establishment, the REITs distribution industry faced difficulties; however, the industry grew rapidly through interest from institutional investors, thus mitigating the establishment problems by 2006. In Korea, more than 108 REITs were operating as of the end of June 2015. REITs contribute significantly to the national economy. The economic impacts on the national economy of the REITs distribution industry was analyzed using input-output (I-O) analysis with respect to production, imports, value-added, and employment. Research design, data, and methodology - The research used an I-O analysis of the activities of the REITs distribution industry in the national economy. The I-O analysis methodology analyzes the economic effects that influence other industries with respect to one unit of external investment. The data for this analysis were the I-O table of 2013 as published by the Bank of Korea in 2014. Results - The findings of this study are as follows. First, if an external input to the REITs distribution industry is 1 won, the overall impact of the product is 1.3869 won, the import induction is 0.0002 won, and the value-added induction is 0.7656 won. A new investment of 659.9 billion won into the REITs industry was estimated to produce a gross effect of 915.2 billion won. Second, if an external input to the REITs distribution industry is 1 billion won, the employment-inducing effects are estimated at 19.6394 individuals. The employment-inducing coefficient of 19.6394 for the REITs distribution industry indicates that the industry created significant employment-more than other industries-because the coefficient was 2.2 times the 2013 industry average employment-inducing coefficient of 8.8. Third, the investment effects of the REITs distribution industry on production induction, value-added induction, and employment induction are assumed to be large in business support services, financing, communications and broadcasting, and professional, scientific, and technical services. Conclusions - The REITs distribution industry was analyzed as having a strong employment inducing, high value added effect. The REITs distribution industry is an excellent alternative for the government authority to create multilateral jobs. Because the REITs distribution industry has a significant positive impact on the national economy, it should be developed. However, the I-O methodology has restrictions with respect to the fixation and timing of the input coefficient. Follow-up research is expected to supplement the analysis method at a specific point in time.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.5
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• pp.278-284
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• 2014

Water temperature due to climate change can be estimated using the air temperature because the air and water temperatures are closely related and the water temperatures have been widely used as the indicators of the environmental and ecological changes. It is highly necessary to estimate the frequency distribution of the air and water temperatures, for the climate change derives the change of the coastal water temperatures. In this study, the distribution function of the air temperatures is estimated by using the long-term coastal air temperature data sets in Korea. The candidate distribution function is the bi-modal distribution function used in the previous studies, such as Cho et al.(2003) on tidal elevation data and Jeong et al.(2013) on the coastal water temperature data. The parameters of the function are optimally estimated based on the least square method. It shows that the optimal parameters are highly correlated to the basic statistical informations, such as mean, standard deviation, and skewness coefficient. The RMS error of the parameter estimation using statistical information ranges is about 5 %. In addition, the bimodal distribution fits good to the overall frequency pattern of the air temperature. However, it can be regarded as the limitations that the distribution shows some mismatch with the rapid decreasing pattern in the high-temperature region and the some small peaks.

• Korean Journal of Plant Taxonomy
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• v.50 no.2
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• pp.154-165
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• 2020

Coastal regions are experiencing habitat changes due to coastal development and global warming. To estimate the future distribution of coastal plants on the Korean Peninsula due to climate change, the potential distribution of ten species of coastal plants was analyzed using the MaxEnt program. The study covered the eastern, western, and southern coastal areas of the Korean Peninsula. We used the distributional data of coastal plants of the East Asian region and the 19 climate variables of WorldClim 2.0. The future potential distribution was estimated using future climate variables projected from three general circulation models (CCSM4, MIROC-ESM, and MPI-ESM-LR), four representative concentration pathways (2.5, 4.5, 6.0, and 8.5), and two time periods (2050 and 2070). The annual mean temperature influenced the estimation of the potential distribution the most. Under predicted future distribution scenarios, Lathyrus japonicus, Glehnia littoralis, Calystegia soldanella, Vitex rotundifolia, Scutellaria strigillosa, Linaria japonica, and Ixeris repens are expected to show contracted distributions, whereas the distribution of Cnidium japonicum is expected to expand. Two species, Salsola komarovii and Carex kobomugi, are predicted to show similar distributions in the future compared to those in the present. The average potential distribution in the future suggests that the effects of climate change will be greater in the west and the south coastal regions than in the east coastal region. These results will be useful baseline data to establish a conservation strategy for coastal plants.