• Journal of the Korean Statistical Society
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• v.27 no.1
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• pp.67-90
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• 1998

In this paper we analytically study model misspecification that arises in regression analysis of nonstationary seasonal time series. We assume the underlying data generating process is a seasonally or a regularly and seasonally integrated process. We first study consequences of totally misspecified cases where seasonal indicator variables, a linear time trend, or another statistically independent seasonally integrated process are used as predictor variables in order to model the nonstationary seasonal behavior of the dependent variable. Then we study consequences of partially misspecified cases where the dependent variable and a predictor variable are cointegrated at some, but not all of the frequencies corresponding to the nonstationary roots.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.143-146
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• 2021

This work presents an automated transistor biasing scheme for analog integrated circuits. In order to effectively bias the transistor at a desired operating point, the proposed method uses a linearized transistor circuit model along with the curve fitted expressions obtained from the pre-simulated I-V characteristics of the actual transistor. As a result, the transistor size that leads to the desired operating point can be easily determined without heavily relying on the circuit simulator, which will lead to significant design time reduction. Furthermore, the proposed method is applied to an actual amplifier circuit where the design time based on the proposed biasing method showed 10× faster than the conventional design approach using the circuit simulator.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.4
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• pp.316-324
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• 2022

This paper uses seasonal auto-regressive integrated moving average (S-ARIMA), which is efficient in seasonality between time-series models, to predict the degradation tendency for lithium-ion batteries and study a method for improving the predictive performance. The proposed method analyzes the degradation tendency and extracted factors through an electrical characteristic experiment of lithium-ion batteries, and verifies whether time-series data are suitable for the S-ARIMA model through several statistical analysis techniques. Finally, prediction of battery aging is performed through S-ARIMA, and performance of the model is verified through error comparison of predictions through mean absolute error.

• Journal of information and communication convergence engineering
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• v.3 no.4
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• pp.209-212
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• 2005

This study proposes hybrid case-based reasoning and genetic algorithms model for customer classification. In this study, vertical and horizontal dimensions of the research data are reduced through integrated feature and instance selection process using genetic algorithms. We applied the proposed model to customer classification model which utilizes customers' demographic characteristics as inputs to predict their buying behavior for the specific product. Experimental results show that the proposed model may improve the classification accuracy and outperform various optimization models of typical CBR system.

• Ocean and Polar Research
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• v.34 no.2
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• pp.185-195
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• 2012

This paper focused on forecasting a short-term production of oysters, which have been farmed in Korea, with distinct periodicity of production by year, and different production level by month. To forecast a short-term oyster production, this paper uses monthly data (260 observations) from January 1990 to August 2011, and also adopts several econometrics methods, such as Multiple Regression Analysis Model (MRAM), Seasonal Autoregressive Integrated Moving Average (SARIMA) Model, and Vector Error Correction Model (VECM). As a result, first, the amount of short-term oyster production forecasted by the multiple regression analysis model was 1,337 ton with prediction error of 246 ton. Secondly, the amount of oyster production of the SARIMA I and II models was forecasted as 12,423 ton and 12,442 ton with prediction error of 11,404 ton and 11,423 ton, respectively. Thirdly, the amount of oyster production based on the VECM was estimated as 10,425 ton with prediction errors of 9,406 ton. In conclusion, based on Theil inequality coefficient criterion, short-term prediction of oyster by the VECM exhibited a better fit than ones by the SARIMA I and II models and Multiple Regression Analysis Model.

• Advances in aircraft and spacecraft science
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• v.7 no.6
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• pp.553-570
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• 2020

To address the problems caused by the strong coupling of an airbreathing hypersonic vehicle's airframe and propulsion to the integrated control system design, an integrated airframe-propulsion model is established, and the coupling characteristics between the aircraft and engine are analyzed. First, the airframe-propulsion integration model is established based on the typical nonlinear longitudinal dynamical model of an air-breathing hypersonic vehicle and the one-dimensional dual-mode scramjet model. Thrust, moment, angle of attack, altitude, and velocity are used as transfer variables between the aircraft model and the engine model. The one-dimensional scramjet model can accurately reflect the working state of the engine and provide data to support the coupling analysis. Second, owing to the static instability of the aircraft model, the linear quadratic regulator (LQR) controller of the aircraft is designed to ensure attitude stability and height tracking. Finally, the coupling relationship between the aircraft and the engine is revealed through simulation examples. The interaction between vehicle attitude and engine working condition is analyzed, and the influence of vehicle attitude on engine safety is considered. When the engine is in a critical working state, the attitude change of the aircraft will not affect the engine safety without considering coupling, whereas when coupling is considered, the attitude change of the aircraft may cause the engine unstart, which demonstrates the significance of considering coupling characteristics.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.165-172
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• 2009

Integrated management model (SNMP/SMI) for lubiquitous egacy remote communication network or service make possible combination of various architecture. However, legacy management system cannot be applied some problems such as inefficient, complexly, implement and large network by reason of integration of voice and data, wired and wireless, and service area between service provider. For improve this, supplied JMX(Java Management eXtensions) on network management technology from SUN. JMX is integrated architecture for existing network management and monitoring. In this paper, we design and implement for integrated network management through multi-protocol agent using JMX.

• Journal of Information Technology Applications and Management
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• v.15 no.1
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• pp.83-97
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• 2008

Today's competitive global market makes most enterprise endeavor to specialize their business areas, and co-operate with trading partners in supply chain by the forms of collaboration, information and business process sharing. However, even the supply chain plan generated by co-operation often fails to be executed successfully, because it was generated without capacities of suppliers and more over nested suppliers. To overcome this limitation, the supply chain plan of an enterprise should be generated truly integrated way. In this paper, we classify business patterns based on scenarios about quotation processing and supply chain planning in self-integrated environment. And we present business process models about four business patterns and describe them, which are classified by whether request for quotation includes information about price, required time periods, and quantity for each required time period and whether it is received from customer or sent to supplier. In addition, we describe the types of supply chain planning problem.

• Spatial Information Research
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• v.21 no.2
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• pp.99-106
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• 2013

Through the rapid economic growth, modern society have achieved the industrialization but needed to respond to climate change and low-carbon green growth on a scale of urban area. Many studies about the low-carbon city and the green city are on going, but most of them are not integrated but go along in each area(construction, transportation, energy, etc) In this paper, we surveyed the current status of researches about information system to design low-carbon city or green city, and define the method to integrate the outcomes from the each area. As a result integrated model of 'Low-carbon Urban Planning integrated System' in the paper, Individual system is developed by way of C/S form because web system raised problems for data load in analysis. The integrated system was decided to develop by way of Web form, and integrated system was developed by can use the analysed DB in the individual system. We expect this study can help future researches to develop more economical and efficient integrated information system model to design the low-carbon city and the green city.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.108-112
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• 2016

This study is established the data-centric design concept, which is the latest design technique, by analyzing existing study literature for its application on the nuclear power plant industry in Korea. This study investigated the data-centric design cases in the advanced companies and suggests a data-centric design integrated system framework by analyzing the major functions of the commercial 3D CAD system, which is globally used in the plant architect engineering. In order to apply the data-centric design integrated system framework to the nuclear power plant industry in Korea, the main functions of a nuclear power plant design information integrated system framework, which can manage the design products of each EPC step and the related information in integrated way, is suggested by analyzing the supplier design, field design process and field design drawings, which have close relation with the plant Architect Engineering (A/E). It is expected that the result of this study would contribute in the dramatic enhancement in the job efficiency of nuclear power plant design process in Korea.