• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.866-881
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• 2012

Han River is a complex water system consisting of many lakes. The water quality of Lake Paldang is significantly affected by incoming flows, which are the South and North branches of the Han River, and the Kyungan Stream. In order to manage the water quality of the Lake Paldang, we should consider the entire water body where the incoming flows are included. The objectives of this study are to develop an integrated river and lake modeling system for Han River system using a multidimensional dynamic model and evaluate the model's performance against field measurement data. The integrated model was calibrated and verified using field measurement data obtained in 2007 and 2008. The model showed satisfactory performance in predicting temporal variations of water level, flow rate and temperature. The Root Mean Square Error (RMSE) for water temperature simulation were $0.88{\sim}2.13^{\circ}C$ (calibration period) and $1.05{\sim}2.00^{\circ}C$ (verification period) respectively. And Nash-Sutcliffe Efficiency (NSE) for water temperature simulation were 1089~0.98 (calibration period) and 0.90~0.98 (verification period). Utilizing the validated model, we analyzed the spatial and temporal distributions of temperature within Han River system. The variations of temperature along the river reaches and vertical thermal profiles for each lakes were effectively simulated with developed model. The suggested modeling system can be effectively used for integrated water quality management of water system consisting of many rivers and lakes.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.710-718
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• 2011

An integrated water quality management of reservoir and river would be required when the quality of downstream river water is affected by the discharge of upstream dam. In particular, for the control of downstream turbidity during flood events, the integrated modeling of reservoir and river is effective approach. This work was aimed to develop a laterally-averaged two-dimensional hydrodynamic and water quality model (CE-QUAL-W2), by which water quality can be predicted in the downstream of Yongdam dam in conjunction with the reservoir model, and to validate the model under two different hydrological conditions; wet year (2005) and drought year (2010). The model results clearly showed that the simulated data regarding water elevation and suspended solid (SS) concentration are well corresponded with the measured data. In addition, the variation of SS concentration as a function of time was effectively simulated along the river stations with the developed model. Consequently, the developed model can be effectively applied for the integrated water quality management of Yongdam dam and downstream river.

• Clean Technology
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• v.28 no.2
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• pp.138-146
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• 2022

Electricity has become a factor that dramatically affects the market economy. The day-ahead system marginal price determines electricity prices, and system marginal price forecasting is critical in maintaining energy management systems. There have been several studies using mathematics and machine learning models to forecast the system marginal price, but few studies have been conducted to develop, compare, and analyze various machine learning and deep learning models based on a data-driven framework. Therefore, in this study, different machine learning algorithms (i.e., autoregressive-based models such as the autoregressive integrated moving average model) and deep learning networks (i.e., recurrent neural network-based models such as the long short-term memory and gated recurrent unit model) are considered and integrated evaluation metrics including a forecasting test and information criteria are proposed to discern the optimal forecasting model. A case study of South Korea using long-term time-series system marginal price data from 2016 to 2021 was applied to the developed framework. The results of the study indicate that the autoregressive integrated moving average model (R-squared score: 0.97) and the gated recurrent unit model (R-squared score: 0.94) are appropriate for system marginal price forecasting. This study is expected to contribute significantly to energy management systems and the suggested framework can be explicitly applied for renewable energy networks.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.405-413
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• 2004

Traditionally, electrical power systems had the vertically-integrated industry structures based on the economics of scale. However power systems have been recently reformed to increase the energy efficiency of the power system. According to these trends, Korean power industry has been partially restructured, and the competitive generation market was opened in 2001. In competitive electric markets, correct demand data are one of the most important issue to maintain the flexible electric markets as well as the reliable power systems. However, the measuring load data can have the uncertainty because of mechanical trouble, communication jamming, and other things. To obtain the reliable load data, an efficient evaluation technique to adust the missing load data is needed. This paper analyzes the load pattern of historical real data and then the turned ARIMA (Autoregressive Integrated Moving Average) model, PCHIP(Piecewise Cubic Interporation) and Branch & Bound method are applied to seek the missing parameters. The proposed method is tested under a variety of conditions and tested with historical measured data from the Korea Energy Management Corporation (KEMCO).

• International conference on construction engineering and project management
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• 2013.01a
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• pp.169-172
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• 2013

Building Information Modeling (BIM) is an effective decision-making platform that helps to save project cost and enhance quality of construction. By generating and linking a wide variety of objects data, BIM can be effectively utilized, and it should be ensured that object properties maintain consistency throughout the project period of design, estimates, construction, maintenance and repair. This study examined how to utilize BIM data in a construction project, by linking cost and schedule data in web environment, to better utilize the information and maintain consistency of the BIM information. To do so, the model integrated WBS data and CBS data, linked them with BIM model to realize 5D simulation in web environment. As a result, cost and schedule data could be simultaneously acquired, and object properties-cost, schedule, location-as well. These are expected to contribute to developing a BIM-based automatic data-processing system in web environment.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.202-210
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• 2017

For the target tracking in cluttered environment using a bistatic sonar whose transmitter and receiver are separately positioned, it is necessary to use data association algorithm via applying a proper measurement modelling to the bistatic sonar. The measurements obtained from the interval of ownship's maneuver have an increased error due to uncertainty of the position of transmitter and receiver. Using the measurements from this interval results in poor target tracking performance. In this paper, an improved tracking performance for the proposed data association based multiple model algorithm is validated by a monte carlo simulation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.241-246
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• 2008

Design of a high-speed railway line requires collaboration of heterogeneous application systems and of engineers with different background. Object-based 3D models with metadata can be a shared information model for the effective collaborative design. In this paper, railway infrastructure information model is proposed to enable integrated and inter-operable works throughout the life-cycle of the railway infrastructures, from planning to maintenance. In order to develop the model, object-based 3-D models were built for a 10km railway among Korea high-speed railway lines. The model has basically three information layers for designers, contractors and an owner, respectively. Prestressed concrete box-girders are the most common superstructure of bridges. The design information layer has metadata on requirements, design codes, geometry, analysis and so on. The construction layer has data on drawings, real data for material and products, schedules and so on. The maintenance layer for the owner has the final geometry, material data, products and their suppliers and so on. These information has its own data architecture which is derived from similar concept of product breakdown structure(PBS) and work breakdown structure(WBS). The constructed RIIM for the infrastructures of the high-speed railway was successfully applied to various areas such as design check, structural analysis, automated estimation, construction simulation, virtual viewing, and digital mock-up. The integrated information model can realize virtual construction system for railway lines and dramatically increase the productivity of the whole engineering process.

• The Journal of Society for e-Business Studies
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• v.1 no.1
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• pp.173-194
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• 1996

In order to adapt today's short product life cycle and rapid technology changes., integrated systems should be extended to support PDM (Product Data Management) or CE(Concurrent Engineering). A PDM/CE environment has been developed and a prototype is Presented in this paper. Features of the PDM/CE environment are 1) integrated product information model (IPIM) includes both data model and integrity constraints, 2) database systems are organized hierarchically so that working data C8Mot be referenced by other application systems until they are released into the global database, and 3) integrity constraints written in EXPRESS are validated both in the local databases and the global database. By keeping the integrity of the product data, undesirable propagation of illegal data to other application system can be prevented. For efficient validation, the constraints are distributed into the local and the global schemata. Separate triggering mechanisms are devised using the dependency of constraints to three different data operations, i.e., insertion, deletion, and update.

• Journal of the Korean Data and Information Science Society
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• v.26 no.2
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• pp.495-504
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• 2015

The Gaussian geostatistical model has been widely used for modeling spatial data. However, this model suffers from a severe difficulty in computation because inference requires to invert a large covariance matrix in evaluating log-likelihood. In addressing this computational challenge, three strategies have been employed: likelihood approximation, lower dimensional space approximation, and Markov random field approximation. In this paper, we reviewed statistical approaches attacking the computational challenge. As an illustration, we also applied integrated nested Laplace approximation (INLA) technology, one of Markov approximation approach, to real data to provide an example of its use in practice dealing with large spatial data.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.4
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• pp.66-76
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• 2008

In medium-sized enterprises that comprise of multiple business branches and companies, various types of information systems are constructed and operated. One of the difficult problems these enterprises face is that integrated information cannot be delivered due to loosely managed mater data. This paper proposes an effective master data management framework for these enterprises. The framework is designed after comparing a tightly controlled centralization model with a coordinated centralization model. Through a case study on a customer master data integration project, the practicality of the framework is explored.