• Journal of Korean Society for Atmospheric Environment
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• v.15 no.6
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• pp.757-765
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• 1999

Lagrangian particle dispersion model(LPDM) is an effective tool to calculate the dispersion from a point source since it dose not induce numerical diffusion errors in solving the pollutant dispersion equation. Fictitious particles are released to the atmosphere from the emission source and they are then transported by the mean velocity and diffused by the turbulent eddy motion in the LPDM. The concentration distribution from the dispersed particles in the calculation domain are finally estimated by applying a particle count method or a Gaussian kernel method. The two methods for calculating concentration profiles were compared each other and tested against the analytic solution and the tracer experiment to find the strength and weakness of each method and to choose computationally time saving method for the LPDM. The calculated concentrations from the particle count method was heavily dependent on the number of the particles released at the emission source. It requires lots fo particle emission to reach the converged concentration field. And resulting concentrations were also dependent on the size of numerical grid. The concentration field by the Gaussian kernel method, however, converged with a low particle emission rate at the source and was in good agreement with the analytic solution and the tracer experiment. The results showed that Gaussian kernel method was more effective method to calculate the concentrations in the LPDM.

• Journal of The Korean Society of Grassland and Forage Science
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• v.41 no.3
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• pp.189-197
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• 2021

Climate change effects are particularly apparent in many cool-season grasslands in South Korea. Moreover, the probability of climate extremes has intensified and is expected to increase further. In this study, we performed climate change vulnerability assessments in cool-season grasslands based on the analytic hierarchy process method to contribute toward effective decision-making to help reduce grassland damage caused by climate change and extreme weather conditions. In the analytic hierarchy process analysis, vulnerability was found to be influenced in the order of climate exposure (0.575), adaptive capacity (0.283), and sensitivity (0.141). The climate exposure rating value was low in Jeju-do Province and high in Daegu (0.36-0.39) and Incheon (0.33-0.5). The adaptive capacity index showed that grassland compatibility (0.616) is more important than other indicators. The adaptation index of Jeollanam-do Province was higher than that of other regions and relatively low in Gangwon-do Province. In terms of sensitivity, grassland area and unused grassland area were found to affect sensitivity the most with index values of 0.487 and 0.513, respectively. The grassland area rating value was low in Jeju-do and Gangwon-do Province, which had large grassland areas. In terms of vulnerability, that of Jeju-do Province was lower and of Gyeongsangbuk-do Province higher than of other regions. These results suggest that integrating the three aspects of vulnerability (climate exposure, sensitivity, and adaptive capacity) may offer comprehensive and spatially explicit adaptation plans to reduce the impacts of climate change on the cool-season grasslands of South Korea.

• Journal of Practical Engineering Education
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• v.14 no.3
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• pp.513-522
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• 2022

Course evaluation serves as helpful information to improve the quality of college education and improve lectures. This study derived the factors through preceding research and FGI to explore the factors that constitute course evaluation and identified the relative importance and priority of the factors through the Analytic Hierarchy Process (AHP). For this, it derived five factors and 15 evaluation items as follows. To secure expertise and fairness in the factor development of course evaluation, the researcher conducted a questionnaire surveying students and teachers and collected a total of 20 valid data. The weight of each evaluation item was calculated based on the data that had been verified for consistency. The analysis concluded that students rated class content, class method, class operation, class evaluation, and class plan as the critical factors in the order of importance, while teachers evaluated class content, class operation, class method, class evaluation, and class plan as important, in that order. Based on the results of this study, I hope that various analyses and studies will be conducted to improve the efficiency and reliability of course evaluation for the quality management of college education.

• Geomechanics and Engineering
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• v.30 no.3
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• pp.313-324
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• 2022

With the development of the economy, people's utilization of underground space are also improved, and a large number of cities have begun to build subways to relieve traffic pressure. The choice of subway station construction method is crucial. If an inappropriate construction method is selected, it will not only waste costs but also cause excessive deformation that may also threaten construction safety. In this paper, a subway station construction scheme selects model based on the AHP-fuzzy comprehensive evaluation. The rationality of the model is verified using numerical simulation and monitoring measurement data. Firstly, considering the economy and safety, a comprehensive evaluation system is established by selecting several indicators. Then, the analytic hierarchy process is used to determine the weight of the evaluation index, and the dimensionless membership in the fuzzy comprehensive evaluation method is used to evaluate the advantages and disadvantages of the construction method. Finally, the method is applied to Liaoyang east road station of Qingdao metro Line 2, and the results are verified by numerical simulation and monitoring measurement data. The results show that the model is scientific, practical and applicable.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.1-10
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• 1995

We have analyzed the reliability of failure models in circuit-switched networks. These models are grid topology circuit-switched networks, and each node transmits a packet to a destination node using a Flooding routing method. We have assumed that the failure of each link and node is independent. We have considered two method to analyze reliability in these models : The Karnaugh Map method and joint probability method. In this two method, we have analyzed the reliability in a small grid topology circuit switched network by a joint probability method, and comared analytic results with simulated ones. For a large grid enormous. So, we have evaluated the reliability of the network by computer simulation techniques. As results, we have found that the analytic results are very close to simulated ones in a small grid topology circuit switched network. And, we have found that network reliability decreases exponentially, according to increment of link or node failure, and network reliability is almost linearly decreased according to increment of the number of links, by which call has passed. Finally, we have found an interesting result that nodes in a center of the network are superior to the other nodes from the reliability point of view.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.12
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• pp.705-712
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• 2003

In this paper, we propose new unified methodologies of reliability and its cost evaluation in power distribution systems. The unified method means that the proposed reliability approaches consider both conventional evaluation factor, i.e. sustained interruptions and additional ones, i.e. momentary interruptions and voltage sags. Because the three voltage quality phenomena generally originate from the outages on distribution systems, the basic and additional reliability indices are summarized considering the fault clearing mechanism. The proposed unified method is divided into the reliability evaluation for calculating the reliability indices and reliability cost evaluation for assessing the damage of customer. The analytic and probabilistic methodologies are presented for each unified reliability and its cost evaluation. The time sequential Monte Carlo technique is used for the probabilistic method. The proposed DVL(Demand Varying Load) model is added to the reliability cost evaluation substituting the average load model. The proposed methods are tested using the modified RBTS(Roy Billinton Test System) form and historical reliability data of KEPCO(Korea Electric Power Corporation) system. The daily load profile of the each customer type in domestic are gathered for the DVL model. Through the case studies, it is verified that the proposed methods can be effectively applied to the distribution systems for more detail reliability assessment than conventional approaches.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.1
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• pp.66-71
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• 2015

The purpose of the study is to establish priorities in integrated medicine policy. Delphi method was used in conducting a survey on integrated medicine specialists regarding the policies of integrated medicine and actions. For specialists in integrated medicine, total 17 persons selected included scholars who performed minimum one study on integrated medicine, medical staff who performing integrated medical service at institutions that implemented integrated medical care or those who were involved in creating or implementing policies on integrated medicine. The first Delphi-method survey conducted from Apr. 14 through 18, while the second survey was carried out from Apr. 21 through 25. To prioritize the policies based on the results of the mini Delphi-method survey, Analytic Hierarchy Process(AHP) was performed for 15 persons answered to mini Delphi-method from May 2 through 16, 2014. From the Delphi-method survey, four policies and 16 actions were obtained. AHP showed the first priority placed on 'Building the Infrastructure of Industrialization in the Integrative medicine' of the 4 policies and 'Developing new diagnostic and treatment instruments' was given the highest priority of the 16 actions. For implementation of integrated medicine policy, the 4 policies and the 16 actions found in this research require government support and should be urgently implemented according to its priority.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.115-120
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• 2000

The analysis of flux distribution under stead-state in large power reactors with assymetry reactivity insertions requires the use of three-dimensional diffusion calculations. For the purpose, consistently formulated modern nodal methods based on higher order interface techniques have become popular tools for flux distributions in large commercial nuclear reactors. Among the earlier developments, the nodal Green's function method obtains its nodal interface equation from the transverse-integrated integral diffusion equation using a finite-medium Green's function. In this method, the outgoing current from a node surface is formulated as a response of the incoming currents and the spatially integrated neutron source within the same node. The well-known nodal expansion method is also based on an interface partial current formulation. Nodal methods high-level interface variables, i.e., interface net current and flux, may be more computationally efficient than the nodal Green's function method because they have one fewer unknown per interface. The Analytic Nodal Method(ANM), which can be classified as an interface net current technique and, was faster in solving some standard benchmark problems than the other two methods.(omitted)

• Fire Science and Engineering
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• v.28 no.2
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• pp.76-81
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• 2014

Structural stability of structural beams at high temperature had been evaluated though a horizontal furnace and a standard fire curve. If a structural method and a material are satisfied with the fire test, those are seemed to be guaranteed the safety of residences, fire services men, and properties of the buildings. However, that requires not only longer period but higher cost for making and testing of each structural element. That restrained from developing new methods and new fire protective materials. In this study, an analytic method was executed to demonstrate whether the analytic method using mechanical properties of structural steel at high temperature with heat transfer theory works is working. In this paper, the surface temperature rising and variance of structural stability of a simple H-section beam with a standard fire curve were evaluated and structural stabilities of H-section beam according to differences from length of beam were suggested.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.180-189
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• 2014

Display quality assessment has been a long standing issue due to the diversity of display devices and the rapid growth of display technology. The conventional display quality assessment methods are mostly those methods which evaluate qualities of a display by measuring physical quantities, but the results from the methods are not equal to the perceived results which are acquired with subjective experiments. Thus, we need to solve the above contrariety as well as establish the quantitative correlation between physical and perceived results. This paper proposes the systematic method of evaluating relative perceived qualities among various display devices and quantifies these relative perceived qualities. The proposed method is based on Analytic Network Process(ANP), which is one of the most popular decision making methods in the business administration field. We also adopted three evaluation criteria, which consist of color, shape and depth, in order to reflect the human visual system and chose eight sub-criteria related to display characteristics via question investigation. We carried out a subjective experiment and the proposed method which evaluated perceived qualities of two display devices(TFT-LCD, OLED) in order to prove the similarity between their results. As a result, it is proved that the order relationship between perceived qualities was the same as the order of results got through the subjective experiment.