• 설비공학논문집
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• 제17권3호
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• pp.262-267
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• 2005

The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate and to model the air-side particulate fouling characteristics of the heat exchangers using accelerated particle loading system. The main variables of the modeling equation are face velocity and dust concentration. The modeling equation shows good agreements with the experimental results at the face velocity of 0.5, 1.0, 1.5 m/s and the dust concentration of 1.28 and $3.84\;g/m^3$. It will be very useful to predict fouling characteristics such as variations of pressure drop and heat transfer capacity in finned-tube heat exchangers of air conditioners.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.306-310
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• 2005

The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. An empirical modeling equation is derived from the experimental results using accelerated tests and it shows good predictions of the fouling characteristics of the slitted finned tube heat exchangers. However the modeling equation predicts only the fouling characteristics of new heat exchangers and it can not predicts fouling characteristics obtained from actual field data. The purpose of this study is to modify the previous modeling equation using the actual field data Therefore an modified modeling equation is proposed and it shows good predictions of the actual fouling characteristics of finned-tube heat exchangers.

• ETRI Journal
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• 제39권5호
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• pp.718-728
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• 2017

Empirical modeling of wireless fading channels using common schemes such as autoregression and the finite state Markov chain (FSMC) is investigated. The conceptual background of both channel structures and the establishment of their mutual dependence in a confined manner are presented. The novel contribution lies in the proposal of a new approach for deriving the state transition probabilities borrowed from economic disciplines, which has not been studied so far with respect to the modeling of FSMC wireless fading channels. The proposed approach is based on equal portioning of the received signal-to-noise ratio, realized by using an alternative probability construction that was initially highlighted by Tauchen. The associated statistical procedure shows that a first-order FSMC with a limited number of channel states can satisfactorily approximate fading. The computational overheads of the proposed technique are analyzed and proven to be less demanding compared to the conventional FSMC approach based on the level crossing rate. Simulations confirm the analytical results and promising performance of the new channel model based on the Tauchen approach without extra complexity costs.

• International Journal of Computer Science & Network Security
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• 제21권7호
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• pp.8-16
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• 2021

The tourism industry is influenced by a large number of factors that affect the development scenarios of the tourism in different ways. At the same time, tourism is an important component of the national economy of any state, forms its image, investment attractiveness, is a source of income and a stimulus for business development. The aim of the article is to conduct an empirical study to identify the importance of cognitive determinants in the development of tourism. The study used general and special methods: systems analysis, synthesis, grouping, systematization, cognitive modeling, cognitive map, pulse method, predictive extrapolation. Target factors, indicators, and control factors influencing the development of tourism in Ukraine are determined and a cognitive model is built, which graphically reflects the nature of the influence of these factors. Four main scenarios of the Ukrainian tourism industry are established on the basis of creating a matrix of adjacency of an oriented graph and forecast modeling based on a scenario approach. The practical significance of the obtained results lies in the possibility of their use to forecast the prospects of tourism development in Ukraine, the definition of state policy to support the industry that will promote international and domestic tourism.

• 한국BIM학회 논문집
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• 제12권3호
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• pp.18-29
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• 2022

Recently, research on the application of BIM has continuously been active not only in architecture but also in civil engineering in order to improve work efficiency across the project's planning, design, construction and maintenance phases. However, the empirical applications of BIM targeting to civil engineering scope of construction sites still lags compared to architectural sized projects. This is because BIM tools are mainly based upon vertical structures of architecture, thereby most of them have difficulties and limitations to get utilized on horizontal structures of civil engineering. Therefore, this study intends to propose automation technology of design using BIM library and to indicate its field availability through case application on a railway project representing linear infrastructure. In addition, it put forward the utilization plan of the automation technology upto 4D and 5D by continue making use of the BIM model created in the project's design stage up through the maintenance stage. The novel method of the technology proposed in this paper incorporates the automatic creation of the BIM library based on two-dimensional tunnel cross-sections and sweeping of it over three-dimensional alignment to create a BIM model of linear infrastructure. The proposed technology is anticipated to improve the efficiecny of modeling process of railway projects based on linear structures.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.635-644
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• 2024

Although the business model(BM) patents act as a creative bridge between technology and the marketplace, limited scholarly attention has been paid to the content analysis of BM patents. This study aims to contextualize converging BM patents by employing topic modeling technique and clustering highly marketable topics, which are expressed through a topic-market impact matrix. We relied on BM patent data filed between 2010 and 2022 to derive empirical insights into the commercial potential of emerging business models. Subsequently, nine topics were identified, including but not limited to "Data Analytics and Predictive Modeling" and "Mobile-Based Digital Services and Advertising." The 2x2 matrix allows to position topics based on the variables of topic growth rate and market impact, which is useful for prioritizing areas that require attention or are promising. This study differentiates itself by going beyond simple topic classification based on topic modeling, reorganizing the findings into a matrix format. T he results of this study are expected to serve as a valuable reference for companies seeking to innovate their business models and enhance their competitive positioning.

• 한국군사과학기술학회지
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• 제20권5호
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• pp.700-707
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• 2017

Recently, the military need more various education and training because of the increasing necessity of various operation. But the education and training of the military has the various difficulties such as the limitations of time, space and finance etc. In order to overcome the difficulties, the military use Defense Modeling and Simulation(DM&S). Although the participants in training has the empirical knowledge from education and training based on the simulation, the empirical knowledge is not shared because of particular characteristics of military such as security and the change of official. This situation obstructs the improving effectiveness of education and training. The purpose of this research is the systematizing and analysing the empirical knowledge using text mining and network analysis to assist the sharing of empirical knowledge. For analysing texts or documents as the empirical knowledge, we select the text mining and network analysis. We expect our research will improve the effectiveness of education and training based on simulation of DM&S.

• 품질경영학회지
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• 제37권3호
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• pp.54-64
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• 2009

This study conducts an empirical analysis of how the suggestion activity, most widely used in quality control activities, interacts with the dimensions of learning organizations. The study also attempts to analyze the results of Six Sigma based on sub-dimensions of learning organizations, which are infrastructure, culture and system. In order for learning and innovation to take place in implementing a Six Sigma program, the organizational infrastructure and culture are created and sustained and then, a learning organization system would become effective. In this study, a empirical model is used to demonstrate such an association. The sample consists of 134 organizations who have implemented a Six Sigma program for more than three years. Using the version 16.0 of AMOS for structural equation modeling, the study estimates the structural equation model that has a Six Sigma organization's infrastructure, culture and system as independent constructs, the suggestion system as a mediator, and the performance of Six Sigma projects as a dependent construct.

• 천문학회보
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• 제37권1호
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• pp.92.1-92.1
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• 2012

In this work we have examined the performance of the WSA/ENLIL cone model provided by Community Coordinated Modeling Center (CCMC). The WSA/ENLIL model simulates the propagation of coronal mass ejections (CMEs) from the Sun into the heliosphere. We estimate the shock arrival times at the Earth using 29 halo CMEs from 2001 to 2002. These halo CMEs have cone model parameters from Michalek et al. (2007) as well as their associated interplanetary (IP) shocks. We make a comparison between CME arrival times by the WSA/ENLIL cone model and IP shock observations. For the WSA/ENLIL cone model, the root mean square(RMS) error is about 13 hours and the mean absolute error(MAE) is approximately 10.4 hours. We compared these estimates with those of the empirical model by Kim et al.(2007). For the empirical model, the RMS and MAE errors are about 10.2 hours and 8.7 hours, respectively. We are investigating several possibilities on relatively large errors of the WSA/ENLIL cone model, which may be caused by cone model velocities, CME density enhancement factor, or CME-CME interaction.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1807-1813
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• 2018

In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators' (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI's function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.