• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.1
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• pp.46-56
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• 2018

This paper aimed to identify main factors of community characters, which have an effect on the land surface temperature(LST) change and estimate the impacting coefficient(ratio) of factors in a significant level of statistics. Chungcheongbuk-do province was selected and then partitioned into city and county areas for the sake of convenience of modeling. LST time series data and the community character data were developed based on Terra Satellite MODIS data and collected from the National Statistical Office, respectively. By the cause and effect relationship between community characters and LST, regression coefficients were estimated using a penal model. In a panel modeling, LST and community characters were used as a dependent variable and explanatory variables, respectively. Panel modeling analysis was carried out using statistical package STATA14 and one-way fixed effect model was selected as the most suitable model to evaluate the regression coefficients in the study area. The impacting ratio of LST change by any explanatory variable derived from the regression coefficients of the panel model fixed. Impacting ratios for industrial areas, elevation ${\times}$ building, energy usage, average window speed, non-urban management area, agricultural, nature and environmental conservation, average precipitation were 3.746, 2.856, 2.742, 0.553, 0.102, 0.071 and 0.003, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.619-622
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• 2005

적용대상 유역은 낙동강수계로 하였으며 소유역 분할은 총 25개로 하였으며, 강우관측소의 선정과 Thiessen 계수의 산정은 최근에 한국수자원공사에서 새로 추가한 강우관측소를 위주로 대상 연도별로 달리하여 강우관측소를 선정하였다. 강우자료의 결측치는 RDS 방법을 사용하여 보완하였다. 대상연도별 소유역별로 일간 유역 평균 강우량을 산정하였다. 적용 모형의 선정은 한국수자원공사 실무부서에서의 적용사례가 빈번한 SSARR 모형을 최종적으로 선정하였다. SSARR 모형의 입력자료를 물리적 매개변수, 수문기상 매개변수 및 내부처리 매개변수로 구분하여 구축하였고 매개변수의 민감도분석과 함께 모형의 보정을 실시하였다. 민감도 분석 결과, 유역유출과 관련된 매개변수에서는 고수시와 저수시의 경우 지표수와 복류수의 분리하는 매개변수에서 민감도가 크게 나타났다. 저수시의 경우 지하수 중 회귀지하수가 차지하는 비율이 크게 나타났고, 지표수, 복류수, 지하수 및 회귀지하수의 저류시간에서 비교적 큰 민감도를 나타내었다. 1983년부터 2003년까지 21개년에 걸쳐 25개 소유역별로 일평균 자연유출량을 산정하여 이를 이용한 반순, 순, 월 및 연평균 자연유출량을 산정하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.444-444
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• 2022

하천 수심 계측은 수심을 사람이 직접 계측하거나 초음파 기반 유속계 (ADCP) 등 최신 계측기기를 이용하여 간접적으로 계측을 실시하고 있다. 하지만 사람이 직접 하천에서 수심을 측정하는 것은 위험이 동반되고, 수심자료의 측정오차가 크게 발생한다. 따라서 수심측정에서 직접 측정 방식의 한계를 극복하기 위해, 초분광 영상의 반사도와 수심이 높은 상관관계를 보이는 것을 활용하여, 초분광 영상 기반 수심 산정 기법을 개발하였다. 초분광 영상 기반 수심 산정 기법은 복수의 파장이 존재하는 초분광영상으로부터 두 개의 파장대의 밴드를 추출하여 모든 경우의 수에 대해 밴드비를 산정한 후, 실측수심과 밴드비 간의 회귀분석을 실시하여 상관계수가 가장 높은 회귀식을 찾아내는 방식이 최적 밴드비 분석법에 기반한다. 최적 밴드비 분석법을 통해 획득된 높은 상관성의 밴드비-수심 관계식을 이용하여 수심을 추정할 수 있다. 이러한 방법은 직접 수심 측정 방식에 비해, 높은 해상도와 밀도, 양질의 데이터를 수집할 수 있는 장점이 있다. 과거 연구에 따르면 저수심부에서의 높은 정확도의 수심추정 결과를 보였지만, 고수심부에서는 실측수심과의 오차도 높아지는 등 정확성이 떨어지는 경향을 보인다. 따라서 본 연구에서는 보다 효율적인 수심계측을 할 수 있도록 최적 밴드비 분석법을 활용한 수심추정에서 신뢰성 있는 수심의 범위를 파악할 수 있는 방법을 제시하고자 한다. 본 연구에서는 대상지역으로 낙동강 본류와 황강 지류 합류부로 선정하였고, 초음파 기반 유속계(ADCP)와 드론을 활용하여 실측수심과 초분광 영상을 취득하였다. 민감도 분석을 위한 수심자료를 0.5m 단위로 분할하였으며, 구간별로 최적 밴드비 분석을 실시하였다. 그 결과, 구간별로 산정된 상관계수와 평균제곱근오차 (RMSE)를 통해 정확도가 높은 구간을 구별할 수 있었다. 또한 해당 구간을 초과하는 수심은 초분광 영상을 통해 추정이 어려운 것으로 판단되며, 분석한 구간까지를 최대 추정 가능 수심으로 정의하였다. 마지막으로 검증을 위해 최대추정가능수심으로 판단된 구간까지의 데이터만 활용하여 최적 밴드비 분석법을 적용하여 상관계수나 평균제곱근오차 결과의 개선여부 확인을 통해, 본 연구에서 제시한 방법이 정확한 최대추정가능수심 구간을 산정할 수 있는지 확인하였다.

• Management & Information Systems Review
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• v.38 no.1
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• pp.1-21
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• 2019

This study focuses on (1) the relationship between the network intensity of top managers and the R&D investment of Korean firms, and (2) the moderating effects of the type (related-division vs. unrelated-division) and system (physical division vs. spin-offs) of corporate division on this relationship. The sample of this study was all type and/or system of corporate division implemented by Korean firms during 18-years (1999-2016) study periods. The results of multiple regression analyses as follow. First, as was expected in hypothesis 1 the network intensity of top managers has a strong positive linear relation with the R&D investment of Korean firms. Second, regarding the moderating effect of division type the results show that related-divisions significantly intensify the positive relationship of the network intensity of top managers with the R&D of Korean firms although unrelated-divisions did not. Third, in the analysis of moderating effect of corporate division system the results present the stronger positive moderating effect of spin-offs rather than physical divisions. The findings of the study implies that strong network intensity of top managers can be beneficial to long-term decision such as R&D investment of Korean firms. They accords to network theory that emphasize the importance of strong network effect among top managers based on their trust. The findings also implies that researchers and practitioners should consider organizational-level factors such as organizational structure, culture, corporate governance, etc as well as individual-level factors such as the characteristics and relationships of organizational members when making the decision for firm.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1253-1262
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• 2014

Regression tree is a tree-structured solution in which a simple regression model is fitted to the data in each node made by recursive partitioning of predictor space. There have been many efforts to apply tree algorithms to various regression problems like logistic regression and quantile regression. Recently, algorithms have been expanded to the panel data analysis such as RE-EM algorithm by Sela and Simonoff (2012), and extension of GUIDE by Loh and Zheng (2013). The algorithms are briefly introduced and prediction accuracy of three methods are compared in this paper. In general, RE-EM shows good prediction accuracy with least MSE's in the simulation study. A RE-EM tree fitted to business survey index (BSI) panel data shows that sales BSI is the main factor which affects business entrepreneurs' economic sentiment. The economic sentiment BSI of non-manufacturing industries is higher than that of manufacturing ones among the relatively high sales group.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.30-38
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• 2006

A new calibration method for five-hole pressure probe is presented. This method provides accuracies better than those based on the traditional regression method. The calibration algorithm uses a single sector interpolation response surface calculated by comparing the regression curve fits with the actual calibration data. A five-hole pressure probe with hemispherical tip was fabricated and calibrated at Reynolds number of $4.11{\times}10^6$/m and flow angle of ${\pm}48$ degrees. Two data prediction models, the least-square regression and a single sector error interpolation, were evaluated. The comparison of these two calibration methods to a five-hole probe is described and discussed. An evaluation of the calibration accuracy is also given.

• Spatial Information Research
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• v.23 no.3
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• pp.23-33
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• 2015

Most data used for urban planning is aggregated by administrative district. Thus, a fundamental limit to analysing the changes of micro-geographical units exists. The object of this study is to estimate spatial development patterns based on characteristic city indicators. Gangnam, an area that was analysed, was divided into hexagon polygons. The development density and characteristic city indicators were input into each polygon. Moreover, this study analysed the influence of characteristic city indicators on development density using multinomial regression analysis. According to the results, distance between a polygon and both a road and a bus stop led to a decrease of development density in the polygon. However, distance between a polygon and a river led to an increase of development intensity. The method of this analysis and the results can be used to disaggregate the zonal data in the urban planing area.

• Journal of Korea Water Resources Association
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• v.43 no.12
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• pp.1029-1038
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• 2010

In meteorology Korea has 2/3 of rain of annual total rainfall at the month of Jun through Sept and it has possibility to have serious flood damage because geographically it is composed of mountainous area with steep slope which account for 70% of its country. Also, the increase of impervious layer due to industrialization and urbanization causes direct runoff, which deteriorates contamination of rivers by moving the contaminated material on the surface at the beginning of rain. In particular, the area of leisure facilities needs the management of water quality absolutely because dense population requires space of park function and place to relax and increases moving capability of non-point pollution source. For disposition of rainfall & runoff, the standard of initial rainfall, which is to be used for the computation of disposition volume, is significant factors for the runoff study of non-point pollution source, Until now, a great deal of study has been done by many researchers. However, it is the current reality that the characteristics of runoff varies according to land protection comprising river basin and the standard of initial rainfall by each researcher is not clearly defined yet. Therefore, in this research, it is suggested that, with the introduction of SOM (Self-Organizing Map), the standard of initial rainfall be determined after analyzing each sectional data by executing pattern classification about runoff and water quality data measured at the test river basin for this research.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.2917-2932
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• 2018

Many researches are accomplished as a result of the efforts of developing the production predicting model to solve the supply imbalance of onions which are vegetables very closely related to Korean food. But considering the possibility of storing onions, it is very difficult to solve the supply imbalance of onions only with predicting the production. So, this paper's purpose is trying to build a sentiment dictionary to predict the price of onions by using the internet articles which include the informations about the production of onions and various factors of the price, and these articles are very easy to access on our daily lives. Articles about onions are from 2012 to 2016, using TF-IDF for comparing with four kinds of TF-IDFs through the documents classification of wholesale prices of onions. As a result of classifying the positive/negative words for price by k-means clustering, DBSCAN (density based spatial cluster application with noise) clustering, GMM (Gaussian mixture model) clustering which are partitional clustering, GMM clustering is composed with three meaningful dictionaries. To compare the reasonability of these built dictionary, applying classified articles about the rise and drop of the price on logistic regression, and it shows 85.7% accuracy.

• Radiation Oncology Journal
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• v.4 no.2
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• pp.89-97
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• 1986

Using as assay for jejunal crypt stem cell survival, dose-response curves for the reproductive capacity of crypt stem cells of mouse jejunum exposed to multifractionated gamma-ray irradiation (single, 2, 3, 4, 5, 8, 10, 12, and 16 fractions) were analyzed and single-dose survival curve of these cells was constructed. The following conclusion were drawn: 1) Survival curves for higher numbers of dose fractions were displaced to higher dose, and characterized by increasingly shallower slopes. 2) The single-dose survival curve had broad shoulder, Dq=460 cGy, remaining near-exponential over initial dose range 0 to 300 cGy, with initial slope 1Do=474 cGy. 3) At fractionated dose En the range of 180 to 450 cGy, the average recovered dose per fraction interval was approximately $50\%$ of the dose per fraction. 4) The value of $\alpha/\beta$ ratio by using of linear regression analysis for the reciprocal dose plots was 8.3 Gy which lied in the range of 6-14 Gy for early-reacting tissues. 5) The linear-quadratic model for dose-response formula offers valid approximations for at 1 doses to be used in radiotherapy, only two parameters to be determined, and considerable convenience in practical applications.