• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.474-474
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• 2015

Horton 지수는 유역에 대한 수문순환의 특성을 정량화하는 지수로서 유역의 습윤량과 기화량의 비로 산출된다. 습윤량과 기화량은 토양 수분과 밀접한 관계를 가지므로 추계학적 거동에 따른 토양수분의 동역학모형을 파악하여 Horton 지수를 산출할 수 있다. 본 연구에서는 추계학적인 토양수분수지 모형을 이용하여 서울, 부산, 대구, 제주 지역을 대상으로 30년간 일 기상자료(강우량, 일 평균기온, 풍속, 상대습도, 일조시간)을 이용하여 Horton 지수를 각각 산출하였으며 Horton 지수에 대한 변동성 분석을 실시하였다. 분석 결과, 모든 대상 유역에서 기후의 계절성에 의하여 Horton 지수가 작아짐을 확인할 수 있었다. 하지만 습윤한 기후를 가진 서울과 건조한 기후를 가진 대구에서는 각각 연 강우량이 많거나 연 강우량이 적은 해에 Horton 지수에 미치는 기후의 계절성의 영향력이 줄어듦을 살펴볼 수 있었다.

• Communications for Statistical Applications and Methods
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• v.3 no.3
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• pp.103-111
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• 1996

정상조건에서는 수명이 상당히 긴 두 개의 부품으로 구성된 병렬형 시스템의 수명검사를 수행하기 위해 고정충격 수명검사의 최적 검사계획에 관하여 고찰하였 다. 시스템을 구성하고 있는 부품의 수명이 서로 독립인 지수분포를 따르는 것으로 가정하여 각 가속조건에서의 부품들의 고장률의 최우추정량을 구하였다. 또한 각 가속조건에서의 부품들의 고장률에 관한 최우추정량의 점근분산의 합을 구하여 이를 최소가 되게 하는 최적 표본 할당비율을 결정하는 방법을 제안하였다.

• Journal of Korea Water Resources Association
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• v.39 no.9 s.170
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• pp.787-800
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• 2006

This study is to develop the drought monitoring system of Korea using drought indices such as PDSI, SPI and MSWSI. To analyze the applicability of three different drought indices, monthly based drought indices have been calculated using various kinds of meteorological and hydrologic data. Also past drought events have been investigated to compare the simulation results, which are the severity, duration and locations using monthly drought indices. The drought map which is made by using PDSI shows the best accordance with past drought events in its severity and duration as well. Also SPI(3) shows good accordance with past drought events. As a results of this study, we concluded that three different drought indices can be used as an effective tool for quantitative drought monitoring.

• The Korean Journal of Applied Statistics
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• v.12 no.2
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• pp.405-414
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• 1999

양쪽중단(doubly censored)된 지수분포에서 모수와 신뢰도함수를 계층적 베이지안(hierarchical Bayesian)방법을 이용하여 추정하였다. 베이즈 계산은 깁스표본기법(Gibbs sampler)을 이용하고 또한 완전조건부 분포(full conditional distribution)의 정량화 상수를 모르는 경우에는 적합기각방법(adaptive rejection sampling)을 이용하였다. 그리고 실제자료를 이용하여 분석을 하였다.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.1
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• pp.155-166
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• 2008

The quantitative bivariate spatial pattern analysis was applied for the water quality and nutrients data of Masan Bay, and for this analysis Pearson's r as aspatial correlation measurement, Moran's I as spatial association measurement and L index as integration of aspatial and spatial measurement methods were used. To understand the aspatial and spatial characteristics implicated in L index, Pearson's r as well as Moran's I were classified into 3 types respectively, and Pearson's r and Moran's I were combined with 9 types, and also quantile of L index value was used for each of those 9 types. Finally, these types were defined as 5 groups having not overlapped L index range. According to the application result of L index groups, bivariate water quality and nutrients showed no aspatial correlation regardless of spatial association in February and July, but they showed aspatial correlation having clustered spatial pattern in May and November. The result of this study providing the guideline for the interpretation of aspatial correlation and spatial association using L index is expected to be helpful for the marine environment pattern analysis using quantitative index for further study.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.397-410
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• 2002

In order to quantitatively identify historical drought conditions and to evaluate their variability, drought indices commonly used. The calculation method for the drought index based on the principal hydrological factors, such as precipitation and reservoir storage, can estimate the duration and intensity of a drought. In this study the Palmer-type formula for drought index is derived for the Nakdong River basin by analyzing the monthly rainfall and meteorological data at 21 stations. The Palmer Drought Severity Index(PDSI) is used for dry land sectors to evaluate the meteorological anomaly in terms of an index which permits time and space comparisons of drought severity. The Surface Water Supply Index(SWSI) is devised for the use in conjunction with the Palmer index to provide an objective indicator of water supply conditions in Nakdong River basin. The SWSI was designed to quantify surface water supply capability of a watershed which depends on river and reservoir water The Standardized Precipitation Index(SPI) is evaluated for various time periods of 1 to 12 months in Nakdong River basin. For the purpose of comparison between drought indices correlation coefficient was calculated between indices and appropriate SPI time period was selected as 10 months for Nakdong River basin. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Nakdong River basin since 1976. It turned out that $'94{\sim}'97$ drought was the worst drought in it's severity. It is found that drought indices are very useful tools in quantitatively evaluating the severity of a drought over a river basin.

• Korean Journal of Construction Engineering and Management
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• v.8 no.4
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• pp.99-109
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• 2007

Risk elements of highway safety facilities are affected by complex environments. Thus, risk-based approach for traffic safety facilities is needed. For this, in this study, qualitative and quantitative risk assessment methodology and procedure for highway safety facilities is proposed, which can be used as risk-based approach incorporating VE process. Also, for the quantitative risk assessment, event tree using EPDO(Equivalent Property Damage Only) with respect to frequency and magnitude of risk events is introduced. As a result, risk index of alternative 1(140cm) and 2(127(cm) which can be used as performance factor in VE approach are estimated.

• Journal of Preventive Medicine and Public Health
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• v.29 no.3 s.54
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• pp.529-538
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• 1996

We investigated the occurrence of color vision loss in 70 organic solvent mixtures exposed workers and in 47 controls. Color Vision was assessed with a color arrangement test designed to identify the defective color sense, the Han Double 15-Hue Test. The results of the test were no significant difference between exposed workers and controls in the proportion of subjects who committed one or two errors. Quantitative analysis, using color confusion index(CCI), showed no signicant difference between exposed workers and controls. A significant linear correlation was present between age and CCI in both exposed workers (CCI=0.0056age + 0.94; r=0.23; p<0.05) and controls(CCI=0.0066age + 0.86; r=0.33; p<0.05). Qualitative analysis of the patterns on the hue circle showed that the prevalence of acquired dyschromatopsia was 21% in both and no significant difference. Multiple regression analyses showed that age was significantly related to color vision loss. These results did not provide evidence of a relationship between organic solvents exposure and incidence of color vision loss. In field studies for monitor the people at risk of the acquired color vision loss involving low-dose organic solvents exposed workers, both quantitative and qualitative information should be considered.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.227-238
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• 2006

Line density index(LDI) was developed to quantify a densely isothermal line rate as standard index in the ocean environment. Theoretical background on the LDI development process restricting index range 0 to 100 was described. And validation test was done for the LDI application condition that total line length is not greater than 1/10 of unit area. NOAA SST(Sea Surface Temperature) data were used for the experimental application of LDI in the South Sea of Korea. Using GIS, $0.1^{\circ}C$ isothermal lines were linearized as vector data form SST raster data, and unit area were built as polygon data. For the LDI calculation, spatial overlapping(line in polygon) was implemented. To analyze the effect of unit area size for the LDI distribution, two cases of unit area size were designed and descriptive statistics was calculated including performing normality test. The results showed no change of LDI's essential characteristics such as mean and normality except for the range of value, variance and standard deviation. Accordingly, it was found that complex structure of thermal front and even smaller scale of front width than unit area size could influence on the LDI distribution. Also, correlation analysis performed between LDI and difference of temperature(${\Delta}T^{\circ}C$), and horizontal thermal gradient(${\Delta}T^{\circ}C/km$) on the front was obtained from linear regression model. This obtained value was compared with the results from previous researches. Newly developed LDI can be used to compare the thermal front regions changing spatio-temporally in the ocean environment using absolute index value. It is considered to be significant to analyze the relationship between thermal front and marine environment or front and marine organisms in a quantitative approach described in this study.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.4
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• pp.60-74
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• 2007

For quantitative analysis of spatio-temporal distribution pattern on marine environment, spatial autocorrelation statistics on the both global and local aspects was applied to the observed data obtained from Gwangyang Bay in South Sea of Korea. Global indexes such as Moran's I and General G were used for understanding environmental distribution pattern in the whole study area. LISAs (local indicators of spatial association) such as Moran's I ($I_i$) and $G_i{^*}$ were considered to find similarity between a target feature and its neighborhood features and to detect hot spot and/or cold spot. Additionally, the significance test on clustered patterns by Z-scores was carried out. Statistical results showed variations of spatial patterns quantitatively in the whole year. Then all of general water quality, nutrients, chlorophyll-a and phytoplankton had strong clustered pattern in summer. When global indexes showed strong clustered pattern, the front region with a negative $I_i$ which means a strong spatial variation was observed. Also, when global indexes showed random pattern, hot spot and/or cold spot were/was found in the small local region with a local index $G_i{^*}$. Therefore, global indexes were useful for observing the strength and time series variations of clustered patterns in the whole study area, and local indexes were useful for tracing the location of hot spot and/or cold spot. Quantification of both spatial distribution pattern and clustering characteristics may play an important role to understand marine environment in depth and to find the reasons for spatial pattern.