• 한국농공학회논문집
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• 제65권1호
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• pp.1-13
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• 2023

Various techniques for bias correction and statistical downscaling have been developed to overcome the limitations related to the spatial and temporal resolution and error of climate change scenario data required in various applied research fields including agriculture and water resources. In this study, the characteristics of three different statistical dowscaling methods (i.e., SQM, SDQDM, and BCSA) provided by AIMS were summarized, and climate change scenarios produced by applying each method were comparatively evaluated. In order to compare the average rainfall characteristics of the past period, an index representing the average rainfall characteristics was used, and the reproducibility of extreme weather conditions was evaluated through the abnormal climate-related index. The reproducibility comparison of spatial distribution and variability was compared through variogram and pattern identification of spatial distribution using the average value of the index of the past period. For temporal reproducibility comparison, the raw data and each detailing technique were compared using the transition probability. The results of the study are presented by quantitatively evaluating the strengths and weaknesses of each method. Through comparison of statistical techniques, we expect that the strengths and weaknesses of each detailing technique can be represented, and the most appropriate statistical detailing technique can be advised for the relevant research.

• Journal of Positioning, Navigation, and Timing
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• 제4권2호
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• pp.43-55
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• 2015

In the case of satellite navigation positioning, the shielding of satellite signals is determined by the environment of the region at which a user is located, and the navigation performance is determined accordingly. The accuracy of user position determination varies depending on the dilution of precision (DOP) which is a measuring index for the geometric characteristics of visible satellites; and if the minimum visible satellites are not secured, position determination is impossible. Currently, the GLObal NAvigation Satellite system (GLONASS) of Russia is used to supplement the navigation performance of the Global Positioning System (GPS) in regions where GPS cannot be used. In addition, the European Satellite Navigation System (Galileo) of the European Union, the Chinese Satellite Navigation System (BeiDou) of China, the Quasi-Zenith Satellite System (QZSS) of Japan, and the Indian Regional Navigation Satellite System (IRNSS) of India are aimed to achieve the full operational capability (FOC) operation of the navigation system. Thus, the number of satellites available for navigation would rapidly increase, particularly in the Asian region; and when integrated navigation is performed, the improvement of navigation performance is expected to be much larger than that in other regions. To secure a stable and prompt position solution, GPS-GLONASS integrated navigation is generally performed at present. However, as available satellite navigation systems have been diversified, finding the minimum satellite constellation combination to obtain the best navigation performance has recently become an issue. For this purpose, it is necessary to examine and predict the navigation performance that could be obtained by the addition of the third satellite navigation system in addition to GPS-GLONASS. In this study, the current status of the integrated navigation performance for various satellite constellation combinations was analyzed based on 2014, and the navigation performance in 2020 was predicted based on the FOC plan of the satellite navigation system for each country. For this prediction, the orbital elements and nominal almanac data of satellite navigation systems that can be observed in the Korean Peninsula were organized, and the minimum elevation angle expecting signal shielding was established based on Matlab and the performance was predicted in terms of DOP. In the case of integrated navigation, a time offset determination algorithm needs to be considered in order to estimate the clock error between navigation systems, and it was analyzed using two kinds of methods: a satellite navigation message based estimation method and a receiver based method where a user directly performs estimation. This simulation is expected to be used as an index for the establishment of the minimum satellite constellation for obtaining the best navigation performance.

• 한국응용과학기술학회지
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• 제37권5호
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• pp.1378-1389
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• 2020

본 연구는 초등학교 비만아동을 위한 통합비만관리프로그램을 개발·적용하여 비만지수, 생활습관 및 자기효능감에 미치는 영향을 파악하기 위한 비동등성 대조군 사전·사후설계이다. 연구대상자는 초등학교 4~6학년 아동으로 실험군 30명과 대조군 28이었다. 통합비만관리프로그램은 교육프로그램 주 1회, 운동프로그램 주 3회로 구성하여 8주간 실시되었다. 수집된 자료는 chi-square test, independent t-test, repeated measure ANOVA를 사용해 분석하였다. 연구결과 실험군에서 체질량지수는 25.83kg/㎡에서 24.82kg/㎡로 감소하였고(p<.05), 체지방률은 대조군에 비해 감소하였으며(p<.05), 비만도도 개선되었다(p<.01). 그러나 근육량은 유의한 변화가 없었다. 중재 후 생활습관(p<.05)), 식이 자기효능감(p<.001), 운동 자기효능감(p<.05)은 향상되었다. 이를 통해 본 연구의 통합비만관리프로그램은 초등학교 비만아동들의 비만도와 비만을 감소시키는 생활습관 개선 및 자기효능감 증진에 효과적인 간호 중재임이 확인되었다.

• 대한물리치료과학회지
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• 제30권1호
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• pp.10-22
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• 2023

Background: The purpose of this study was to investigate the effect of brain education-based exercise and KPEM manual therapy integrated program on the sleep and quality of life of cancer patients. Design: Seventy subjects who were diagnosed with cancer and were undergoing treatment volunteered to participate in this study. All subjects used a nonequivalent control group pretest-posttest design for either the experimental group or the control group. In the final analysis, there were 25 subjects in the experimental group and 18 subjects in the control group. Methods: For 12 weeks, the experimental group performed brain education-based exercise (20 minutes) and KPEM manual therapy (50 minutes), and the control group performed basic physical therapy and autonomous exercise. For evaluation, the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K) and the quality of life index were measured after intervention using the European Organization for Research and Treatment of Cancer (EORTC-3.0Ver). Effect between groups, time effect over time, and group^*time interaction were analyzed through a pre-test before and after the 12-week intervention period, and repeated measure ANOVA after 12 weeks of the integrated program intervention. All statistical significance levels were set at α=.05. Results: The PSQI in the time effect (p=.001) and the group^*time interaction (p<.001) were statistically significant. In terms of EORTC, QL2 and PF2 were significant in time effect (p=.024; p=.021) and group^*time interaction (p=.007; p=.021), whereas in RF2, significance was only found in group^*time interaction (p=.028). In symptom indicators, time effect was the only significant factor in FA, SL, AP, and CO, respectively (p=.002; p=.028; p=.041; p =.005) and in DY, there were significant differences in the time effect (p=.016) and group^*time interaction (p=.002). Conclusion: The brain education-based exercise and KPEM manual therapy integrated program effectively improves the sleep and quality of life of cancer patients. It is considered that this exercise and therapy can be actively used as a psychological, emotional, and physically complementary physical therapy intervention to improve the quality of life of cancer patients.

• 보건행정학회지
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• 제7권1호
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• pp.155-182
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• 1997

Objectives : This study was designed to compare North Korea and South Korea in measures of the quality of life (physical quality of life index and human development index) and to investigate the impact of selected medical and socioeconomic factors on PQL variables. Data and Methods : The World Bank, the United Nations Development Programme, and Population Reference Bureau were the principal sources of statistical data of 121 countries. Variables included infant mortality, life expectancy at birth, literacy rate, secondary school enrollment (male and female), GNP per capita, population per doctor, daily calorie supply per capita, and a composite PQL index. The Ordinary Least Square model was employed for cross-countries analysis. Findings : Both countries under quite different political and economic systems saw big improvememts in the quality of life, reducing mortality and prolonging life expectancy during the past three decades. In recent decad, however, North Korea has experienced abrupt exacerbation in the quality of life. Significant improvements in infant mortality of the population wer attributable mainly to GNP per capita and the secondary school enrollemt of female. The principal predictors of life expectancy at birth were population per doctor, infant mortality, and literacy rate. The secondary school enrollment of female and population per doctor were significantly associated with improvements in the physical quality of life index (PQLI). Conclusion : The results of this study confirmed a point illustrated by other studies : The association between quality of life as a measure of health status and socioeconomic factors was strong and positive. The important contribution of educational attainment in general, female education level in particular to improvements in the quality of life deserves good news for building an integrated health care system in the reunified Korea, taking into account the high level of education two koreas are enjoying. Meanwhile, when a sharp drop in the quality of life has been observed in North Korea under serious economic difficulties and food shortage in recent decade, the significant contribution of economic development to improvements in the quality of life poses bad nows for reunifying Korean health care in economic terms.

• 한국수자원학회논문집
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• 제39권9호
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• pp.801-812
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• 2006

본 연구에서는 PDSI, SPI, MSWSI 등의 가뭄지수를 이용하여 가뭄을 단계별로 모니터링 할 수 있는 통합가뭄지수를 개발하였으며 개발된 통합가뭄지수에 의해 작성된 한반도의 가뭄도를 과거 가뭄과 비교 검증한 결과 매우 잘 일치하는 결과를 얻을 수 있었다. 따라서 통합가뭄지수가 가뭄을 정량적으로 모니터링 하는데 유용한 지표로 활용될 수 있을 것으로 판단된다 또한, 기상청에서 시행하고 있는 기온, 강수량의 장 단기 예보자료를 이용하여 가뭄지수의 예측치를 산정 한 후, 미래에 가뭄상황이 어떻게 진행될 것인가에 대한 가뭄전망기법을 개발하였으며 한반도 전역에 대한 실시간 가뭄전망이 가능하도록 전체 시스템을 구축하였다. 뿐만 아니라 가뭄기초 자료 관리, 가뭄지수 산정 및 가뭄현황도 작성 등 종합적인 가뭄정보 분석을 위한 가뭄 모니터링시스템을 개발하여 웹을 통하여 일반인들에게 제공할 수 있도록 시스템을 구축하였다.

• 한국습지학회지
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• 제19권3호
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• pp.311-317
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• 2017

본 연구에서는 낙동강수계에서의 수질 모니터링 자료를 이용하여 수질지수를 산정하고 생활환경기준과 비교를 통해 수질상태를 검토하였다. 수질지수는 환경부에서 현재 시행되고 있는 실시간수질지수(RWQI) 방법인 CCME-WQI을 사용하였으며 수질항목은 pH, DO, EC, 수온, TOC, T-N, T-P에 대해 7개 평가항목으로 선정하였다. 평가기간은 최근 3년간(2013년~2015년)으로 선정하였으며 해당 기간 내 측정된 수질 모니터링 자료를 이용하였다. 평가결과, 전 기간 평가 결과는 지수와 생활환경기준이 비슷한 경향을 보이나 월별 평가는 지수와 BOD, T-P 결과가 다르게 나타났다. 따라서 효율적인 하천관리를 위해서는 단일 수질항목만의 평가보다 복합적인 평가가 보다 필요할 것으로 신뢰성이 있는 것으로 검토되었다.

• Journal of the Korean Data and Information Science Society
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• 제22권2호
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• pp.335-351
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• 2011

오경주와 김태윤 (2007) 등은 위기 관련 데이터의 희귀성 에서 발생하는 문제를 해결하기 위해 과거 금융시장이 안정적이었던 구간을 기준 구간으로 설정하고 기준 구간의 금융시장 움직임을 점 근 자기회귀 모형으로 적합한 후 현재의 금융시장 상황과 비교하여 불안정 지수를 도출할 것을 제안하였다. 그러나 비모수 기법인 신경망을 사용하여 도출된 불안정 지수가 기준 구간의 데이터에 지나치게 의존하는 관계로 불안정 지수가 종종 실제 경제상황을 제대로 반영하지 못하는 것으로 관찰되고 있다. 본 연구에서는 비모수 기법인 신경망과 모수 기법인 선형모형을 이용하여 기준구간에 대한 적합을 독립적으로 수행하여 두 종류의 불안정성 지수들을 도출한 후 이 둘을 결합한 통합 불안정성 지수를 사용할 것을 제안한다. 두 지수의 적절한 통합을 위해 신경망과 선형모형을 통해 도출된 두 지수의 최적 결합비율을 부여하는 방법을 제안하며 제안기법의 타당성을 국내 주식시장 대상으로 검증하였다.

• 한국컴퓨터정보학회논문지
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• 제26권5호
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• pp.47-53
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• 2021

희소한 평가 데이터는 사용자들 간의 신뢰할만한 유사도 산출을 저해하기 때문에 추천 시스템을 위한 메모리 기반의 협력 필터링 기법의 성능을 저하시킨다. 기존 연구의 많은 결과물은 이 데이터 희소성 문제를 해결하기 위해 개발되었으며, 가장 단순하고 대표적인 업적은 자카드 계수를 활용하는 방법들이다. 이 계수는 두 사용자의 공통 평가 항목수를 반영하며, 그들 간의 유사도를 보다 정확하게 계산하기 위해 전통적인 유사도 척도와 통합된다. 그러나, 그러한 통합은 데이터 희소성의 정도를 고려하지 않은 매우 단순한 방법이다. 본 연구는 두 사용자의 자카드 계수값에 의거하여 다른 유사도 척도를 적용하는 새로운 아이디어를 제시한다. 제안 방법에서 사용하는 파라미터의 최적값을 구하기 위하여 성능 실험을 진행하였고, 다른 관련된 방법들과 비교 평가하였다. 결과로서, 제안 방법은 예측 정확도와 추천 정확도에 있어서 가장 우수하거나 대등한 성능을 보였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.164-164
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• 2023

This study investigates the importance of flood-influencing factors on the accuracy of flood risk mapping using the integration of remote sensing-based and machine learning techniques. Here, the Extreme Gradient Boosting (XGBoost) and Random Forest (RF) algorithms integrated with GIS-based techniques were considered to develop and generate flood risk maps. For the study area of NAPA County in the United States, rainfall data from the 12 stations, Sentinel-1 SAR, and Sentinel-2 optical images were applied to extract 13 flood-influencing factors including altitude, aspect, slope, topographic wetness index, normalized difference vegetation index, stream power index, sediment transport index, land use/land cover, terrain roughness index, distance from the river, soil, rainfall, and geology. These 13 raster maps were used as input data for the XGBoost and RF algorithms for modeling flood-prone areas using ArcGIS, Python, and R. As results, it indicates that XGBoost showed better performance than RF in modeling flood-prone areas with an ROC of 97.45%, Kappa of 93.65%, and accuracy score of 96.83% compared to RF's 82.21%, 70.54%, and 88%, respectively. In conclusion, XGBoost is more efficient than RF for flood risk mapping and can be potentially utilized for flood mitigation strategies. It should be noted that all flood influencing factors had a positive effect, but altitude, slope, and rainfall were the most influential features in modeling flood risk maps using XGBoost.