• The Journal of Bigdata
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• v.6 no.1
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• pp.91-113
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• 2021

Despite the influence of real estate in the Korean asset market, it is not easy to predict market trends, and among them, apartments are not easy to predict because they are both residential spaces and contain investment properties. Factors affecting apartment prices vary and regional characteristics should also be considered. This study was conducted to compare the factors and characteristics that affect apartment prices in Seoul as a whole, 3 Gangnam districts, Nowon, Dobong, Gangbuk, Geumcheon, Gwanak and Guro districts and to understand the possibility of price prediction based on this. The analysis used machine learning algorithms such as neural networks, CHAID, linear regression, and random forests. The most important factor affecting the average selling price of all apartments in Seoul was the government's policy element, and easing policies such as easing transaction regulations and easing financial regulations were highly influential. In the case of the three Gangnam districts, the policy influence was low, and in the case of Gangnam-gu District, housing supply was the most important factor. On the other hand, 6 mid-lower-level districts saw government policies act as important variables and were commonly influenced by financial regulatory policies.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5B
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• pp.449-457
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• 2011

Recently, increasing heavy rainfalls due to climate change and/or variability result in hydro-climatic disasters being accelerated. To cope with the extreme rainfall events in the future, hydrologic frequency analysis is usually used to estimate design rainfalls in a design target year. The rainfall data series applied to the hydrologic frequency analysis is assumed to be stationary. However, recent observations indicate that the data series might not preserve the statistical properties of rainfall in the future. This study incorporated the residual analysis and the hydrologic frequency analysis to estimate design rainfalls in a design target year considering the non-stationarity of rainfall. The residual time series were generated using a linear regression line constructed from the observations. After finding the proper probability density function for the residuals, considering the increasing or decreasing trend, rainfalls quantiles were estimated corresponding to specific design return periods in a design target year. The results from applying the method to 14 gauging stations indicate that the proposed method provides appropriate design rainfalls and reduces the prediction errors compared with the conventional rainfall frequency analysis which assumes that the rainfall data are stationary.

• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.861-869
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• 2001

Objective : In this study, we investigated the relationship between the histologic grading of meningiomas and proliferative potentials determined by the Ki-67, proliferating cell nuclear antigen(PCNA) and flow cytometry (FCM) with the aim of determining whether these potentials can be used as a parameter to the proliferative activity, in particular of atypical and malignant meningiomas. Methods : This study consisted of 47 meningiomas(6 malignant, 14 atypical, and random sampled 27 benign meningiomas). By immunohistochemical staining of Ki-67 and PCNA on formalin-fixed, paraffin-embedded sections, the anti-human rabbit polyclonal antibody against Ki-67 antigen and anti-PCNA monoclonal antibody(PC10) scores were counted. FCM was also performed on paraffin-embedded tissue using a selective staining technique for DNA. DNA ploidy, S-phase fraction, and proliferative index(PI)) were determined. Results : The results are summarized as follows ; 1) Proliferation rates as assessed by Ki-67 and PCNA closely correlated with the degree of anaplastic histologic features. 2) Proliferative potentials determined by FCM(S-phase fraction and PI) were not able to distinguish between benign and atypical/malignant meningiomas. 3) DNA ploidy was not a useful indicator of histologic grade in these tumors. 4) Proliferative potentials such as Ki-67 staining index(SI) and PCNA SI did not correlate with the ploidy pattern. 5) There was a linear correlation between Ki-67 SI and PCNA SI, but we could not find a correlation between Ki-67 SI and S-phase fraction or PI. Our results also did not show a statistically signficant correlation between PCNA SI and S-phse fraction or PI. Conclusions : We conclude that evaluation of the proliferative potentials with Ki-67 and PCNA is important as an additional factor for the prediction of malignancy in meningiomas. A dual study of Ki-67 and PCNA SIs on the same tissue might improve the accuracy with which the proliferative potential of a tumor can be predicted. We demonstrated that FCM in meningiomas is not valuable in predicting the behavior of these neoplasms, but we did observe a trend toward more malignancy with higher percent S-phase fraction and higher PI. Analysis of the S-phase fraction and PI might therefore be a useful tool to discriminate among histologic grades of meningiomas.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.605-611
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• 2015

A synthetic strain of ducks (Anas platyrhynchos) was developed by introducing genes for long duration of fertility to be used as mother of mule ducklings and a seven-generation selection experiment was conducted to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. Reciprocal crossbreeding between Brown Tsaiya LRI-2 (with long duration of fertility) and Pekin L-201 (with white plumage mule ducklings) ducks produced the G0. Then G1 were intercrossed to produce G2 and so on for the following generations. Each female duck was inseminated 3 times, at 26, 29, and 32 weeks of age. The eggs were collected for 14 days from day 2 after AI. Individual data regarding the number of incubated eggs (Ie), the number of fertile eggs at candling at day 7 of incubation (F), the total number of dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) with plumage colour were recorded. The selection criterion was the breeding values of the best linear unbiased prediction animal model for F. The results show high percentage of exhibited heterosis in G2 for traits to improve (19.1% for F and 12.9% for H); F with a value of 5.92 (vs 3.74 in the Pekin L-201) was improved in the G2. Heritabilities were found to be low for Ie ($h^2=0.07{\pm}0.03$) and M ($h^2=0.07{\pm}0.01$), moderately low for Dm ($h^2=0.13{\pm}0.02$), of medium values for H ($h^2=0.20{\pm}0.03$) and F ($h^2=0.23{\pm}0.03$). High and favourable genetic correlations existed between F and Dm ($r_g=0.93$), between F and H ($r_g=0.97$) and between Dm and H ($r_g=0.90$). The selection experiment showed a positive trend for phenotypic values of F (6.38 fertile eggs in G10 of synthetic strain vs 5.59 eggs in G4, and 3.74 eggs in Pekin L-201), with correlated response for increasing H (5.73 ducklings in G10 vs 4.86 in G4, and 3.09 ducklings in Pekin L-201) and maximum duration of the fertile period without increasing the embryo mortality rate. The average predicted genetic response for F was 40% of genetic standard deviation per generation of selection. The mule ducklings' feather colour also was improved. It was concluded that this study provided results for a better understanding of the genetics of the duration of fertility traits in the common female duck bred for mule and that the selection of a synthetic strain was effective method of improvement.