• Environmental Engineering Research
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• v.14 no.4
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• pp.200-210
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• 2009

The modern era of water quality modeling in the United States began in the 1960s. Pushed by advances in computer technology as well as environmental sciences, water quality modeling evolved through five broad periods: (1) initial model development with mainframe computers (1960s - mid 1970s), (2) model refinement and generalization with minicomputers (mid 1970s - mid 1980s), (3) model standardization and support with microcomputers (mid 1980s - mid 1990s), (4) better model access and performance with faster desktop computers running Windows and local area networks linked to the Internet (mid 1990s - early 2000s), and (5) model integration and widespread use of the Internet (early 2000s - present). Improved computer technology continues to drive improvements in water quality models, including more detailed environmental analysis (spatially and temporally), better user interfaces and GIS software, more accessibility to environmental data from on-line repositories, and more robust modeling frameworks linking hydrodynamics, water quality, watershed and atmospheric models. Driven by regulatory needs and advancing technology, water quality modeling will continue to improve to better address more complicated water bodies and pollutant types, and more complicated management questions. This manuscript describes historical trends in water quality model development in the United States, reviews current efforts, and projects promising future directions.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.83-86
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• 2005

This paper presents a method for point-based 3D building reconstruction using LiDAR data and digital map. The proposed method consists of three processes: extraction of building roof points, identification of roof types, and 3D building reconstruction. After extracting points inside the polygon of building, the ground surface, wall and tree points among the extracted points are removed through the filtering process. The filtered points are then fitted into the flat plane using ODR(Orthogonal Distance Regression). If the fitting error is within the predefined threshold, the surface is classified as a flat roof. Otherwise, the surface is fitted and classified into a gable or arch roof through RMSE analysis. Based on the roof types identified in automated fashion, the 3D building reconstruction is performed. Experimental results showed that the proposed method classified successfully three different types of roof and that the fusion of LiDAR data and digital map could be a feasible method of modelling 3D building reconstruction.

• Journal of KIBIM
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• v.10 no.1
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• pp.23-29
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• 2020

The vacant houses commonly observed in urban aging are considered to be representative signs of urban decline. Vacant houses are themselves vulnerable to security, and in particular, they are exposed to disasters due to poor management, which can accelerate the decline of the area. This study is to classify the area and analyze the causes and characteristics of the occurrence of vacant houses by type based on the data through the survey on the vacant houses in Incheon. This research analyze vacant house data survey so to characterized and categorized types of vacant houses. The criteria of vacant houses analysis are population density, population growth, aging extent. In conclusion there are four types of region in Incheon area according to housing types, hazard classes, building age and building areas. Type A is inner city, type B is mixed, type C is expandable and type D is unsular types.

• Journal of Korean Society for Quality Management
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• v.26 no.1
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• pp.99-107
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• 1998

This paper presents a software reliability model that is based on a nonhomogeneous poisson process. The major contribution of this model is combining multiple failure types with imperfect debugging by use of S-shaped mean value function. The software reliability model allows for three different types of errors: Critical errors are the most difficult to detect and the most expensive to remove. Major errors are moderately difficult to detect and fairly expensive to remove. Minor errors are easy to detect and inexpensive to remove. The model also allows for the introduction of any of these types of errors during the removal of an error. A numerical example is provided to illustrate the above techniques.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.11
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• pp.4145-4162
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• 2021

During the period of epidemic prevention and control, contact tracing systems are developed in many countries, to stop or slow down the progression of COVID-19 contamination. However, the privacy issues involved in the use of contact tracing apps have also attracted people's attention. First, we divide contact tracing techniques into two types: Bluetooth Low Energy (BLE) based and Global Positioning System (GPS) based techniques. In order to clear understand the system structure and its elements, we create data flow diagram (DFD) of each types. Second, we analyze the possible privacy threats contained in various types of contact tracing apps by applying LINDDUN, which is a threat modeling technique for personal information protection. Third, we make a comparison and analysis of various contact tracing techniques from privacy point of view. These studies can facilitate improve tracing and security performance to contact tracing apps through comparisons between different types.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.225-238
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• 2022

The purpose of this study is to explore the performance characteristics and laws of the symbol mark design of representative regional history museums in China, as well as the preferences of Chinese audiences for the symbol marks of different types of Chinese regional history museums. First, the performance theme, performance type, and type performance tendency of symbol mark modeling of the regional history museums among the top 100 museums in China are analyzed. Second, design laws based on the interrelationship of performance theme types and design performance types are explored. Finally, the questionnaire survey is carried out to explore preference from the aspects of attention, readability, closeness, originality, aesthetics and comprehensiveness. According to the results, the theme of regional history is the most in terms of themes. As for the modeling performance types, the concrete type and the visualization of Chinese character are the most. According to the content characteristics of different performance types, the following model characteristics are formed: expressing the theme of regional history, architecture, and regional natural ecological environment through the concrete type, expressing the concept through the abstract type, and expressing the concept and implying some building features through the geometric abstract figure. The three forms of the literal type, the concrete type expressing architecture, regional history, and regional natural ecological environment theme content, and the abstract type expressing concept are combined with each other, and expressed through the visualization of character, the mixture of abstract and literal type, the mixture of concrete and abstract type, and the mixture of concrete and abstract literal type in the mixture type. According to the survey results, Chinese audiences have higher preference for the concrete type in the symbol mark performance type and the regional historical theme in the performance content.

• Communications for Statistical Applications and Methods
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• v.25 no.6
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• pp.605-618
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• 2018

Risk management has been a crucial part of the daily operations of the financial industry over the past two decades. Value at Risk (VaR), a quantitative measure introduced by JP Morgan in 1995, is the most popular and simplest quantitative measure of risk. VaR has been widely applied to the risk evaluation over all types of financial activities, including portfolio management and asset allocation. This paper uses the implementations of multivariate GARCH models and copula methods to illustrate the performance of a one-day-ahead VaR prediction modeling process for high-dimensional portfolios. Many factors, such as the interaction among included assets, are included in the modeling process. Additionally, empirical data analyses and backtesting results are demonstrated through a rolling analysis, which help capture the instability of parameter estimates. We find that our way of modeling is relatively robust and flexible.

• Transactions on Electrical and Electronic Materials
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• v.14 no.6
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• pp.283-290
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• 2013

This paper illustrates the possibilities of using the program ATP-Draw (Alternative Transient Program) for the modeling of power networks to study power quality problems with highly detailed analyses. The Program ATP-Draw is one of the most widespread and oldest programs. A unique characteristic of this program is its public domain and the existence of forums and study committees where new application cases and modification are presented and shared publicly. In this paper, to study the propagation of harmonics through a power network, a part of an industrial power network was modeled. The network contains different types of electric components, such as transformers, transmission lines, cables and loads, and there is a source of harmonics that injects $3^{rd}$, $5^{th}$, $7^{th}$, $9^{th}$ and $11^{th}$ harmonic currents into the network, causing a distortion of the wave form of the currents and voltages through the power network.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.96-99
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• 2003

Land cover map is a typical GIS database which shows the Earth's physical surface differentiated by standardized homogeneous land cover types. Satellite images acquired by Landsat TM were primarily used to produce a land cover map of 7 land cover classes; however, it now becomes to produce a more accurate land cover classification dataset of 23 classes thanks to higher resolution satellite images, such as SPOT-5 and IKONOS. The use of the newly produced high resolution land cover map of 23 classes for such activities to estimate non-point sources of pollution like water pollution modeling and atmospheric dispersion modeling is expected to result a higher level of accuracy and validity in various environmental monitoring results. The estimation of pollution from non-point sources using GIS-based modeling with land cover dataset shows fairly accurate and consistent results.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.109-116
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• 2016

A flexible concrete mattress (FCM) is a structural system for protecting submarine power or communication cables under various load types. To evaluate its of protection performance, a numerical analysis of an FCM under an anchor collision was performed. The explicit dynamics of the finite element analysis program ANSYS were used for the collision analysis. The influences of the steel reinforcement modeling and collision angle of the anchor on the collision behavior of the FCM were estimated. The FCM damage was evaluated based on the results of the numerical analysis considering the numerical modeling and collision environment.