• 한국지구과학회지
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• 제42권4호
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• pp.445-458
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• 2021

Gravity Recovery and Climate Experiment (GRACE) gravimeter satellites observed the Earth gravity field with unprecedented accuracy since 2002. After the termination of GRACE mission, GRACE Follow-on (GFO) satellites successively observe global gravity field, but there is missing period between GRACE and GFO about one year. Many previous studies estimated terrestrial water storage (TWS) changes using hydrological models, vertical displacements from global navigation satellite system observations, altimetry, and satellite laser ranging for a continuity of GRACE and GFO data. Recently, in order to predict TWS changes, various machine learning methods are developed such as artificial neural network and multi-linear regression. Previous studies used hydrological and climate data simultaneously as input data of the learning process. Further, they excluded linear trends in input data and GRACE/GFO data because the trend components obtained from GRACE/GFO data were assumed to be the same for other periods. However, hydrological models include high uncertainties, and observational period of GRACE/GFO is not long enough to estimate reliable TWS trends. In this study, we used convolutional neural networks (CNN) method incorporating only climate data set (temperature, evaporation, and precipitation) to predict TWS variations in the missing period of GRACE/GFO. We also make CNN model learn the linear trend of GRACE/GFO data. In most river basins considered in this study, our CNN model successfully predicts seasonal and long-term variations of TWS change.

• 지식경영연구
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• 제19권4호
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• pp.59-76
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• 2018

With the arrival of the big data era, customer data and data mining analysis have gradually dominated the process of Customer Relationship Management (CRM). This phenomenon indicates that customer data along with the use of information techniques (IT) have become the basis for building a successful CRM strategy. However, some companies can not discover valuable information through a large amount of customer data, which leads to the failure of making appropriate business strategy. Without suitable strategies, the companies may lose the competitive advantage or probably go bankrupt. The purpose of this study is to propose CRM strategies by segmenting customers into VIPs and Non-VIPs and identifying purchase patterns using the the VIPs' transaction data and data mining techniques (K-means clustering and association rules) of online shopping mall in Korea. The results of this paper indicate that 227 customers were segmented into VIPs among 1866 customers. And according to 51,080 transactions data of VIPs, home product and women wear are frequently associated with food, which means that the purchase of home product or women wears mainly affect the purchase of food. Therefore, marketing managers of shopping mall should consider these shopping patterns when they build CRM strategy.

• 지능정보연구
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• 제23권3호
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• pp.69-94
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• 2017

최근 빅데이터 분석 수요의 지속적 증가와 함께 관련 기법 및 도구의 비약적 발전이 이루어지고 있으며, 이에 따라 빅데이터 분석은 소수 전문가에 의한 독점이 아닌 개별 사용자의 자가 수행 형태로 변모하고 있다. 또한 전통적 방법으로는 분석이 어려웠던 비정형 데이터의 활용 방안에 대한 관심이 증가하고 있으며, 대표적으로 방대한 양의 텍스트에서 주제를 도출해내는 토픽 모델링(Topic Modeling)에 대한 연구가 활발히 진행되고 있다. 전통적인 토픽 모델링은 전체 문서에 걸친 주요 용어의 분포에 기반을 두고 수행되기 때문에, 각 문서의 토픽 식별에는 전체 문서에 대한 일괄 분석이 필요하다. 이로 인해 대용량 문서의 토픽 모델링에는 오랜 시간이 소요되며, 이 문제는 특히 분석 대상 문서가 복수의 시스템 또는 지역에 분산 저장되어 있는 경우 더욱 크게 작용한다. 따라서 이를 극복하기 위해 대량의 문서를 하위 군집으로 분할하고, 각 군집별 분석을 통해 토픽을 도출하는 방법을 생각할 수 있다. 하지만 이 경우 각 군집에서 도출한 지역 토픽은 전체 문서로부터 도출한 전역 토픽과 상이하게 나타나므로, 각 문서와 전역 토픽의 대응 관계를 식별할 수 없다. 따라서 본 연구에서는 전체 문서를 하위 군집으로 분할하고, 각 하위 군집에서 대표 문서를 추출하여 축소된 전역 문서 집합을 구성하고, 대표 문서를 매개로 하위 군집에서 도출한 지역 토픽으로부터 전역 토픽의 성분을 도출하는 방안을 제시한다. 또한 뉴스 기사 24,000건에 대한 실험을 통해 제안 방법론의 실무 적용 가능성을 평가하였으며, 이와 함께 제안 방법론에 따른 분할 정복(Divide and Conquer) 방식과 전체 문서에 대한 일괄 수행 방식의 토픽 분석 결과를 비교하였다.

• 지역연구
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• 제33권4호
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• pp.3-17
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• 2017

본 연구는 Oxford Economics에서 제공하는 Global Cities Forecast 자료(2013)를 이용하여 한국의 7대 광역시를 포함한 전 세계 주요도시의 경쟁력지수 및 분배지수를 산출하고 그 종합순위를 정리하였다. 도시경쟁력지수는 규모지표, 비율지표, 성장률지표 등 총 18개 경제관련 지표를 선택하였고, 분배지수로서 지니계수를 이용하였다. 경쟁력지수와 지니계수 간의 관계를 분석하기 위하여 LOGIT 회귀모형을 이용하여 분석하였으며 추정결과 소득불평등(지니계수) 증가는 5년 시차로 볼 때 도시경쟁력지수 또한 경제성장률 변화에 음(-)의 영향을 미치고 있으며 통계적으로 유의하였다. 지니계수가 높을수록 도시경쟁력에 부정적으로 영향을 미친다는 추정결과에 따라 도시경쟁력지수에 분배지수를 포함시켜 총 19개 지표로 세계주요 도시 및 국내 7대 광역시의 글로벌 도시경쟁력 위상을 정리하였다. 2012년 실질가치 기준으로 계산된 서울의 도시 종합경쟁력 순위는 2010년 세계 59위, 2015년 세계 74위, 2030년에는 세계 185위로 급격히 하락하는 것으로 나타나고 있으며 나머지 6대 광역시의 종합경쟁력지수도 모두 하락하는 것으로 나타났다. 도시경쟁력 하락은 장기적으로 국가경쟁력 하락을 의미하므로 도시경쟁력 확보를 위한 문제점 진단과 전략적 방안의 강구가 절실히 요구된다.

• Journal of Korea Trade
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• 제27권5호
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• pp.113-136
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• 2023

Purpose - Global production chains and their impacts on economic growth have drawn extensive attention from researchers. Close relationships among global production chains, export and economic growth have been illuminated, as evidenced by the fast and stable economic growth of East Asian economies. These economies perform various roles within global production chains using offshoring, in which the impact of import on domestic gross output is as strong as that of export. The impact of import on economic growth would depend on whether imported inputs substitute or complement domestic inputs production, which is likely to vary according to individual countries' functions within global production chains. The economic growth of concerned countries would also be diverse. However, little attention has been paid to the impact brought by imports compared to its significance. Design/methodology - The principal methodology used in this paper is structural decomposition analysis (SDA), widely chosen to elucidate the impact of various factors on domestic gross output using input-output tables. This paper extracts trade data of six Asian economies from the World Input-Output Database (WIOD) 2016 release that covers 43 countries for the period 2000-2014. The extracted data is then categorised into 37 sectors. First, this paper calculates the Feenstra-Hanson Offshoring Index (OSI) of each country. It then applies SDA to measure the changes in each economy's gross output, export, import input coefficients, and domestic input coefficients. Finally, after taking the first difference from pooled time-series data, it estimates the correlations between imported input coefficients and OSI using the ordinary least square (OLS) method. Findings - The main findings of this paper can be summarised as follows. Firstly, all six countries have increasingly engaged in global production chains, as evidenced by the growing size of OSI. Secondly, there are negative correlations in five countries except Japan, with sectoral differences. Thirdly, changes in import input coefficients are not negative in all six countries, indicating that offshoring does not necessarily substitute for domestic inputs production but does complement it and, therefore, fosters their economic growth. This is observed in China, Indonesia, Korea and Taiwan. Offshoring has led to an increase in the use of imported inputs, which has, in turn, stimulated domestic inputs production in these countries. Originality/value - While existing studies focus on the role of export in evaluating the impact of participating global production chains, this paper explicitly examines the unexplored impact of import on domestic gross output by considering both the substitution and the complementary effect, using the WIOD. The findings of this paper suggest that Asian economies have achieved fast and stable economic growth not only through successful export management but also through effective import management within global production chains. This paper recommends that the Korean government and enterprises carefully choose offshoring strategies to minimise disruption to domestic production chains or foster them.

• 대한한의학회지
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• 제25권2호
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• pp.127-137
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• 2004

Objectives : The purpose of this investigation was to evaluate the effects of Sohaphyang-won (SH) on the alteration in gene expression in a hypoxia model using cultured rat cortical cells. Methods : E18 rat cortical cells were grown in neurobasal medium containing B27 supplement. On 12 DIV, SH was added ($20\mu\textrm{g}/ml$) to the culture media for 24 hrs. On 14 DIV, cells were given a hypoxic insult (2% O2/5% CO2, $37^{\circ}C$, 3 hrs), returned to normoxia and cultured for another 24 hrs. Total RNA was prepared from SH-untreated (control) and -treated cultures and alteration in gene expression was analyzed by microarray using rat 5K-TwinChips. Results : Effects on some of the genes whose functions are implicated in neural viability are as follows: 1) For most of the genes altered in expression, the global M values were between -05 to +0.5, Among these, 1517 genes were increased in their expression by more than global M +0.1, while 1480 genes were decreased by more than global M -0.1. 2) The expression of apoptosis-related genes such as Bad (global M =0.35), tumor protein p53 (T53) (global M =0.28) were increased, while v-akt murine thymoma viral oncogene homolog 1 (Akt1) was decreased. 3) The expression of hemoglobin alpha 1 (probably neuroglobin) was increased by about 3.2-fold (global M =1.7). 4) The expression of antioxidation-related catalase gene was increased (global M =0.26). 5) The expression of PKCzeta (prkcz), an upstream kinase of MAPK, was increased (global M =0.29). 6) The expression of retinoic acid receptor alpha (RAR), which may regulate transcription in hypoxic stress, was increased (global M =10.27). Conclusions : In summary, the microarray data suggest that SH doesn't increase the expression of oxygen capture-, anti-oxidation- and 'response to stress' -related genes but decreases some anti-apoptosis genes which would help protect the hypoxic cells from apoptosis.

• 대기
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• 제29권2호
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• pp.149-164
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• 2019

The purpose of this study is to introduce the improvement of current operational climate prediction system of KMA and to compare previous and improved that. Whereas the previous system is based on GloSea5GA3, the improved one is built on GloSea5GC2. GloSea5GC2 is a fully coupled global climate model with an atmosphere, ocean, sea-ice and land components through the coupler OASIS. This is comprised of component configurations Global Atmosphere 6.0 (GA6.0), Global Land 6.0 (GL6.0), Global Ocean 5.0 (GO5.0) and Global Sea Ice 6.0 (GSI6.0). The compositions have improved sea-ice parameters over the previous model. The model resolution is N216L85 (~60 km in mid-latitudes) in the atmosphere and ORCA0.25L75 ($0.25^{\circ}$ on a tri-polar grid) in the ocean. In this research, the predictability of each system is evaluated using by RMSE, Correlation and MSSS, and the variables are 500 hPa geopotential height (h500), 850 hPa temperature (t850) and Sea surface temperature (SST). A predictive performance shows that GloSea5GC2 is better than GloSea5GA3. For example, the RMSE of h500 of 1-month forecast is decreased from 23.89 gpm to 22.21 gpm in East Asia. For Nino3.4 area of SST, the improvements to GloSeaGC2 result in a decrease in RMSE, which become apparent over time. It can be concluded that GloSea5GC2 has a great performance for seasonal prediction.

• 한국농림기상학회지
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• 제12권4호
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• pp.232-237
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• 2010

작물모형의 필수 입력자료인 일간 누적일사량은 다른 기상요소들에 비해 관측밀도가 낮아 대안으로서 일조 시간을 기반으로 한 Angstrom-Prescott 모형 추정값이 널리 사용되고 있다. 추정의 간편성 때문에 월 단위 일사량 및 일조시간 자료가 모형의 계수(Angstrom-Prescott coefficients, 이하 A-P 계수) 도출에 사용되고 있지만 작물생육모형에서 요구하는 일간 일사량을 추정하는 데는 한계가 있다. A-P 계수 도출에 월 단위 자료 대신 일 단위 자료를 사용함으로써 기대되는 개선효과를 판정하기 위해 일사량과 일조시간을 동시에 관측하는 국내 18개 기상대의 25년 간(1983~2007) 일 단위 및 월 단위 자료로부터 A-P 계수를 각각 도출하였다. 이 계수들의 공간분포로부터 일사 미관측 기상대 8곳의 A-P 계수를 추출하고 지점별 일 단위 및 월 단위 계수를 실측 일조시간자료에 적용하여 2008년 9월부터 2009년 8월까지 일사량을 일별로 추정하였다. 같은 기간 중 이들 일사 미관측기상대에 검증용 일사계를 설치하여 얻은 실측 일사량자료와 비교한 결과 일 단위자료 기반의 추정오차가 월 단위자료 기반 오차에 비해 평균 9.3% 적었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.715-720
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• 2002

There are many global/continental or large area land cover mapping projects because land cover is one of key parameters in environmental studies. Though ground truth collection is a important and difficult task in land cover mapping, it is usually performed independently in each project without any cooperation between them. This is the background of the development of Global Land Cover Ground Truth (GLCGT) database by the cooperation of many projects and researchers. The developed GLCGT database will be used freely by any researcher. This cooperative and common development of GLCGT database will realize reliable and continuously improved land cover ground truth data. It also eliminates duplicated efforts of ground truth collection among projects.

• 품질경영학회지
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• 제43권1호
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• pp.43-56
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• 2015

Purpose: In this research, We made the conceptual frameworks for SEM(Structural Equation Modeling) on Global quality's origin and empirical research. Developing conceptual frameworks is an important step in theory building and theory testing. This research model was developed by strong theoretical foundation which is quality and systematical model. Methods: Questionnaire was developed, and data was collected and analyzed for this study. The analysis was conducted using SEM(Structural Equation Modeling). Results: Results show that process quality and interaction quality are important drivers in customer satisfaction. Customer satisfaction is strongly impact on customer loyalty(repeated purchase). Conclusion: In turbulent business era, Global company require not only excellent quality but also create customer oriented culture and control over operation in the foreign country.