• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.406-406
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• 2022

댐은 물을 담아두어 강수량에 따른 유량을 조절하거나, 하천의 물을 끌어와 사용할 수 있게 하는 역할 또는 모래, 자갈 등을 막아 걸러주는 역할 등을 수행한다. 우리나라의 경우 지역별, 계절별 강수량의 차이가 크며, 그로 인해 유량이 지역과 계절에 영향을 크게 받는다. 이런 변동성을 조절하기 위해 치수와 이수, 두 분야 모두에서 댐의 중요성이 크다. 이뿐만 아니라 기후변화로 인한 변동성의 극대화로 인해 그 중요성이 나날이 커지고 있다. 댐을 운영하기 위해서는 강수량에 따른 댐 유입량의 예측을 하여, 적절한 방류 시기 및 방류량을 결정하는 것이 가장 중요한 요소이다. 기후변화로 인한 변동성의 증대로 홍수와 가뭄과 같은 재해의 빈도와 심도가 커지면서 댐 유입량의 예측이 어려워지고 있다. 댐의 설계나 유지관리를 위해 홍수에 대해서는 많은 연구가 이루어졌던 것에 비해, 갈수기의 경우 물 부족으로 인해 유량이 적어져 댐 유입량에 대한 정확한 산정이 어려워 가뭄 시 댐 유입량에 관한 연구가 홍수 시에 비해 적게 연구된 것이 실정이다. 따라서 가뭄 시 댐 연구를 위해 갈수기의 댐 유입량에 대한 정확한 산정 및 예측의 필요성이 대두되고 있다. 이번 연구에서는 댐 주변의 지하수위와 하천수위의 관계성을 보이고 각각 다른 변량 간의 시간적 종속성을 고려하는 동시에 상호연관된 변량의 시간적 종속성을 동시에 고려한VARX(vector autoregressive-exogenous) 모델을 이용하여 정확한 댐의 유입량을 산정 및 예측하고 그에 대한 검증을 시행하여, 댐 분야에서 가뭄에 대비할 수 있는 근간을 마련하였다.

• Journal of Distribution Science
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• v.14 no.4
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• pp.47-53
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• 2016

Purpose - The objective of this study is to investigate the dynamic relationships among Advertising Cost (AD), Newly Registered Users(NRU), and Buying Users(BU) of Social Network Game(SNG). SNG is getting pervasive mainly due to the rapid growth of mobile game and Social Network Service(SNS). It would be helpful for marketing researchers interested in SNG and related practitioners to understand the changes in AD, NRU, and BU with time as well as the effects on one another in mutual and dynamic way. Research Design, Data, and Methodology - Necessary data were collected from Social Network Game(SNG) company. AD, NRU, and BU are endogenous variables, but new event such as launching (event) and holidays(holiday) are exogenous dummy variables. Vector Auto regression (VAR) model is generally used to examine and capture the dynamic relationships among endogenous variables. VAR model can easily capture dynamic and endogenous relationships among time-series variables. Vector Auto regression with Exogenous variables(VARX) is a model in which exogenous variables are added to VAR. To investigate this study, VARX is applied. Result - By estimating the VARX model, the author finds that the past periods' NRU affect negatively and significantly the present AD, and past periods' BU have a positive and significant impact on the increase of AD. In addition, the author shows that the past periods' AD and BU have a positive and significant effect on the increase of NRU, and the past periods' AD affect positively and significantly BU. While the impact of AD on NRU happens after 3 or 4 days (carryover effect), that of AD on BU comes about within just 1 or 2 days (immediate effect). The effect of BU on NRU can be considered as word of mouth (WOM effect). Therefore, SNG companies can obtain not only the growth of revenue but also the increase of NRU by increasing BU. Through those results, the author can also find that there are significant interactions between endogenous variables. Conclusion - This study intends to investigate endogenous and dynamic relationships between AD, NRU, and BU. They also give managerial implications to practitioners for SNS and SNG firms. Through this study, it is found that there exist significant interactions and dynamic relationships between those three endogenous variables. The results of this study can have meaningful implications for practitioners and researchers of SNG. This research is unique in that it deals with "actual" field data and intend to find "actual" relationships among variables unlike other related existing studies which intend to investigate psychological factors affecting the intention of game usage and the intention of purchasing game items. This study is also meaningful by showing that the increase of BU can be a good strategy for "killing birds with one stone" (i.e., revenue growth and NRU increase). Although there are some limitations related with future research topics, this research contributes to the current research on SNG marketing in the above mentioned ways.

• Knowledge Management Research
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• v.22 no.4
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• pp.135-155
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• 2021

With the emergence of various types of social media and the diversification of their roles, it has become essential for marketers to understand how different types of social media influence consumers' purchase decisions differently and derive more detailed strategies by social media types. This study classifies social media into two types-expression-focused social media and relationship-focused social media-and investigates the relationship between consumer purchases and social media mentions by type. Using the Seoul bike-sharing data and time-series data for social media mentions, we apply the VAR model with Exogenous Variables (VARX). We find that the increase of product mentions in expression-focused social media positively affects both the number of new customers (customer acquisition) and the number of shared bike rentals, while that in relationship-focused social media negatively affects the number of new customers only. In addition, as new customers increase, the product mentions in both types of social media increase. On the other hand, the number of bike rentals has no significant effect in increasing social media mentions regardless of type. This study contributes to the social media and sharing economy literature and provides managerial implications for establishing sophisticated social media marketing in bike-sharing businesses.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.1
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• pp.189-201
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• 2022

The study empirically examines the impact of monetary fundamentals along with global oil prices on the Pak-rupee exchange rate using the monthly data over 2001-2020. Employing the cointegrating vector autoregressive with exogenous variables (VARX) and vector error correction model with exogenous variables (VECMX), the study analyzes the impact of domestic monetary fundamentals while considering the foreign variables as weakly exogenous. In order to account for the structural breaks in the data, the Lagrange multiplier (LM) unit root test with two structural breaks has been used (Lee & Strazicich, 2003). The empirical results reveal that the domestic and foreign monetary variables significantly explain the exchange rate movements in Pakistan both in the long run and in the short run. The dynamic properties of the monetary model of exchange rate have been analyzed using the persistence profile analysis and generalized impulse response functions (GIRFs). The results reveal that the responses of shocks to domestic monetary fundamentals are consistent with the predictions of the monetary model of the exchange rate. Furthermore, being a net oil importer, a rise in global oil prices significantly depreciated the Pak-rupee exchange rate over the period of study. The global financial crisis (GFC) and pandemic (COVID-19) were also found to cause the Pak-rupee exchange rate depreciation.