• Journal of the korean society of oceanography
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• v.34 no.2
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• pp.73-85
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• 1999

When typhoons passed around the Korea Strait, some observation in this strait carried out by Mizuno et al. (1986) gives us the following oceanographic features; 1) the direction of the observed current was opposite to the northeasterly wind, 2) temperature rapidly increased having a time lag as the depth deepens, after then decreased with oscillation. A primitive equation ocean model that makes use of a sigma-coordinate system and incorporates a typhoon model was used to examine the mechanism to generate these phenomena. The model region covers the East China Sea, the Yellow Sea, and a portion of the East Sea (Japan Sea). The model well reproduces the observed features, especially in temperature field, and clearly manifests how the above observed features happened. From early time when the typhoon was located in low latitude, an alongshore northward current in the west of Kyushu (hereafter the West Kyushu Current) is generated by an alongshore wind in the typhoon. This current flows into the eastern channel, as a coastal jet, regardless to the wind field within the Korea Strait during this period. The above observed phenomena are generated by this current. The model results indicate that when typhoons pass around the Korea Strait, the West Kyushu Current is generated, and oceanographic condition in the strait should be greatly influenced by this current.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.110-120
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• 2006

There have been developed many structural and fluid rotorcraft analysis models in rotorcraft community, and also lots of investigations have been conducted to combine these two models. These investigations turn out to be good at predicting the airloads precisely, but they have not taken the blade nonlinear deflection into account. For this reason, the present paper adopts a sophisticated structural model which can describe three-dimensional nonlinear deflection of the blade. And it is combined with two types of aerodynamic model. First one is generalized Greenberg type of finite-time aerodynamic model, which is originally established for a fixed wing, but later modified to be suitable for coupled flap-lag-torsional aeroelastic analysis of the rotor blade. Second aerodynamic model is based on the unsteady source-doublet panel method coupled with a free wake model. The advantages of the present method are capabilities to consider thickness of the blade and more precise wake effects. Transient responses of the airloads and structural deflections in time domain are mainly analyzed in this paper.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.5
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• pp.868-889
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• 2022

Fashion companies are using a big data approach as a key strategic analysis to predict and forecast sales. This study investigated the effectiveness of the past sales, web search volume, information amount, brand promotion, and the advertising endorser on the sales forecasting model. The study conducted the autoregressive distributed lag (ARDL) time series model using the internal and external social big data of a national fashion brand. Results indicated that the brand's past sales, search volume, promotion, and amount of advertising endorser information amount significantly affected the sales forecast, whereas the brand's advertising endorser search volume and information amount did not significantly influence the sales forecast. Moreover, the brand's promotion had the highest correlation with sales forecasting. This study adds to information-searching behavior theory by measuring consumers' brand involvement. Last, this study provides digital marketers with implications for developing profitable marketing strategies on the basis of consumers' interest in the brand and advertising endorser.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.4
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• pp.406-413
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• 1993

Among 2-dimensional coastal hydrodynamic finite element models time stepping ADCIRC and STEPM. and harmonic FUNDY and TEA models were compared in order to find out their characteristics and analyze ernr. General feasibility and capability of models were studied by comparing model results with an analytical solution on some reference points and L$_2$norm error in quarter annular domain where analytical solution can be obtained. According to these tests harmonic models FUNDY and TEA were nearly coinciding with analytical solutions and gave better results than time stepping models. STEPM was at least 5 times better than ADCIRC in L$_2$norm error test and it was 7 times worse than harmonic models. It was expected and concluded that these errors might come from phase lag due to cold start condition and nonlinear effect in basic equations of time stepping models.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.92-95
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• 2002

Bioavailability study was conducted to elucidate the relationship between sorption/desorption and biodegradation of sorbed phenanthrene in seven different soils. Mineralization kinetics was determined for phenanthrene-sorbed soil slurries inoculated with Pseudomonas putida (ATCC strain 17484). Two biodegradation models were used to fit mineralization kinetics; (i) a first-order degradation model and (ii) a coupled degradation-desorption model. The biodegradation rates were in order of vermicompost >Bion peat > 50% organoclay > Pahokee > blank (no soil, medium only) > montmorillonite > Ohio shale. The mineralization rate constants increased as desorption-resistance of phenanthrene increased. Among the tested sorbents, active biodegradation of phenanthrene was observed in vermicompost and Bion peat. Biodegradation in these two sorbents exhibited little lag time and a high maximum mineralized capacity. The role of sorption/desorption in bioavailability of phenanthrene sorbed in soils was discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.26-35
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• 2004

As part of thrust control technology research on turbopump-fed type liquid-propellant rocket engine system, the low frequency dynamic characteristics of turbopump was investigated. It can be described that a turbopump system has a 1st-order lag element. When the value, which was resulted by subtraction of the variation of turbine moment with respect to the variation of revolution number from the variation of pump moment with respect to the variation of revolution number, was positive, the time constant of the 1st-order lag element was positive which stood for a stable system. Increasing the above-mentioned valve within positive range leaded to the increase of response and to the decrease of controllability.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.1
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• pp.121-128
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• 2019

This study analyses the relationship between the real estate market and economic growth in Vietnam, a country with a fledgling real estate market. Research data included economic growth rate and growth rate of the real estate market in Vietnam. The research used quarterly data for the period from 2005: Q1 to 2018: Q1. With the characteristics of Vietnam, there has been no real estate index up to now; therefore, the research used data on growth rates of the real estate market. In addition, the real estate market in Vietnam is still young, so the data series is very short, which is a limitation of this research. With qualitative and quantitative methods especially with the Vector Auto Regressive (VAR) model; the results of the study indicate new findings, unlike previous studies, including: (1) The real estate market positively impacts Vietnam's economic growth, most noticeably in the second quarter lag and the fourth quarter lag, and then its trend impacts inversely; (2) The real estate market and economic growth in Vietnam have fluctuated over time with many risks that are affected by the past shocks of these factors. From these findings, we proposed some managerial implications for managing the real estate market with economic growth in Vietnam sustainably.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.61-68
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• 2021

The exchange rate is considered a tool improving the volume of exports and reducing imports. This paper aims to determine the impact of the exchange rate on exports and imports between Vietnam and the United States in the context of the trade war. The research uses Autoregressive Distributed Lag (ARDL) and Nonlinear Autoregressive Distributed Lag (NARDL) Model in the time-series data from 2010:1 to 2020:9. The ARDL's results support that real exchange rate impact on export and import volumes, but less than the trade war. The trade war helps trade balance increase 0.35%, while the exchange rate increases trade balance 0.191% when the Vietnamese currency devalues 1% in the long run. In the short term, the real exchange rate makes the trade balance decrease. Therefore, the J curve exists between Vietnam and the U.S. The NARDL expresses that the exchange rate is asymmetric both in the short term and the long term. The findings of this study point to two important elements. Firstly, the exchange rate plays a minor role in exports and imports. Secondly, trade war plays a vital role in increasing exports and imports volume between two countries, and the J curve exists between the two countries.

• Asia pacific journal of information systems
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• v.32 no.4
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• pp.707-727
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• 2022

Industrial revolution 4.0 makes business competition more challenging and will impact the instability of the company's financial performance. Dynamic environmental conditions make it difficult for companies to make predictions in making decisions. Investing in information technology (IT) is one way for companies to maintain financial stability and competitive advantage in dynamic competition. Resource-Based Theory (RBT) explains that information technology (IT) is a resource that can create a competitive advantage for the company. This study aims to examine the moderating role of dynamic industrial environments and IT strategic emphasis on the relationship between a lag effect of IT investment and firm's financial performance volatility. Using the data of companies listed on the Indonesia Stock Exchange (IDX) for five years starting from 2013-2017, the method used to estimate the research model's parameters is the generalized method of moments (GMM) approach. The results show that the industrial environment and the emphasis on IT strategy have a role in moderating and strengthening the relationship between the time lag in IT investment in reducing the firm's financial performance volatility.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.27-36
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• 2014

This paper presents an adaptive wide-area damping controller (WADC) based on generalized predictive control (GPC) and model identification for damping the inter-area low frequency oscillations in large-scale inter-connected power system. A recursive least-squares algorithm (RLSA) with a varying forgetting factor is applied to identify online the reduced-order linearlized model which contains dominant inter-area low frequency oscillations. Based on this linearlized model, the generalized predictive control scheme considering control output constraints is employed to obtain the optimal control signal in each sampling interval. Case studies are undertaken on a two-area four-machine power system and the New England 10-machine 39-bus power system, respectively. Simulation results show that the proposed adaptive WADC not only can damp the inter-area oscillations effectively under a wide range of operation conditions and different disturbances, but also has better robustness against to the time delay existing in the remote signals. The comparison studies with the conventional lead-lag WADC are also provided.