• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.111-119
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• 2011

The main objective of this study was to evaluate the effects of control-release fertilizer (CRF) on pollutant loadings from a small watershed. The Baran watershed, 386 ha in size, was selected as the study site, and the AGNPS (Agricultural Non-point Source Pollution) model was used to evaluate the effects of fertilizer types. Digital maps of digital elevation (DEM), slope distribution, channel, flow direction, landuse, soil, and curve number were extracted from the study watershed. Model parameters related to hydrology and water quality were calibrated and validated by comparing model predictions with the observed data collected for 2 years (1999 to 2000). Calibration and validation resulted in $R^2$ values of 0.75-0.91 for all the water quality parameters. All the paddy fields (21.2 %) of the study watershed were sprayed by either CRF or NPK (standard fertilizer). In CRF application, total nitrogen (TN) load was 4.9% less than NPK application, however total phosphorus (TP) load was 0.7 % more than NPK application. In CRF application, considering only paddy fields in the study area, TN load was 38.7 % less than NPK application. Using CRF in paddy fields could be one of the ways to reduce pollutant loadings from agricultural watersheds, however, in order to confirm it, more researches about effects of using CRF are necessary.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2153-2166
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• 2017

Web apps have a problem that they cause same data to be repetitively retrieved, processed, and displayed when web browsers load different web pages. To resolve the problem, this paper presents and evaluates a new method for restructuring of Java web apps. This approach dynamically analyzes Java web apps from the MVC (Model-View-Controller) architecture point of view and identifies redundant data by using the composite view pattern. Then the input apps are restructured in order not to load the redundant data when users make requests for new pages. This restructuring generates new web apps that conform to the MVC architecture and improve the performance of input web apps. The experimental results showed that when compared to legacy web apps, the restructured apps' response time was reduced on desktop PCs and mobile devices by 38% and 55%, respectively. In addition, case studies using open-source web apps showed the applicability of the proposed approach.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.3
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• pp.269-276
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• 2001

Ultrasonic testing of composite materials is much more difficult than that of isotropic materials, because of the beam skew phenomenon caused by their elastic anisotropy. An established analytical method exists for elastic wave propagation in anisotropic media as a result of previous research efforts. Yet, due to the complexity of the analytical method, solution of real problems must resort to the numerical method. In this work, analytical solutions have first been obtained for the wavefield due to a point source in a unidirectional fiber-reinforced composite, which may be modeled as transversely isotropic. Then, the corresponding numerical solutions have been obtained using the mass-spring lattice model(MSLM). The two solutions have agreed well with each other. Other problems such as reflection from free boundaries and scattering from cracks have also been solved numerically, and the results have been investigated from the viewpoint of wave mechanics. The numerical model whose validity has been confirmed by this work will be of great use in simulating ultrasonic testing of composite materials.

• Journal of Korea Water Resources Association
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• v.40 no.3
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• pp.251-263
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• 2007

In this paper, we constructed the integrated watershed model system, SWAT-Nak Dong that include areal mean precipitaiton, runoff and water balance components in the Nak Dong river basins and with this model system we are capable of estimating streamflows for ungaged river stations and analyzing the variations of the streamflows. SWAT(Soil and Water Assessment Tool) is a conceptual, continous time model that was developed in the early 1990s to assist water resource managers in assessing the impact of management and climate on water supplies and non-point source pollution III watersheds and large river basins. Using the SWAT-Nak Dong system and various scenarios, we analyzed and evaluated the dams and water uses effects on the streamflows.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.640-652
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• 2012

Many studies have investigated the smart grid architecture and communication models in the past few years. However, the communication model and architecture for a smart grid still remain unclear. Today's electric power distribution is very complex and maladapted because of the lack of efficient and cost-effective energy generation, distribution, and consumption management systems. A wireless smart grid communication system can play an important role in achieving these goals. In this paper, we describe a smart grid communication architecture in which we merge customers and distributors into a single domain. In the proposed architecture, all the home area networks, neighborhood area networks, and local electrical equipment form a local wireless mesh network (LWMN). Each device or meter can act as a source, router, or relay. The data generated in any node (device/meter) reaches the data collector via other nodes. The data collector transmits this data via the access point of a wide area network (WAN). Finally, data is transferred to the service provider or to the control center of the smart grid. We propose a wireless cooperative communication model for the LWMN.We deploy a limited number of smart relays to improve the performance of the network. A novel relay selection mechanism is also proposed to reduce the relay selection overhead. Simulation results show that our cooperative smart grid (coopSG) communication model improves the end-to-end packet delivery latency, throughput, and energy efficiency over both the Wang et al. and Niyato et al. models.

• Journal of Distribution Science
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• v.15 no.3
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• pp.81-89
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• 2017

Purpose - Universities are fostering the development of closer relationships with students due to the increase in competition among universities. Universities are placing greater emphasis on relationship quality as a source of competitive advantage. Thus relationship marketing has become an important strategic theme in higher education. The purpose of this study is to investigate the effects of faculty trustworthiness on relationship building process in the context of relationship marketing. For this study, faculty trustworthiness is divided into competence, benevolence, and integrity. And relationship development variables are composed of satisfaction, commitment, positive WOM, and negative WOM. Research design, data, and methodology - To empirically evaluate the proposed research model, this study was carried out using the survey with undergraduate students who were taking business courses. The 270 questionnaires were asked, and a total of 245 respondents provided complete and usable data. The sample consisted of 143 males(58.4%) and 102 females(41.6%). The variables of proposed model were measured on a 5-point Likert scale. The structural equation modeling analysis was used for the hypothesis test. Results - The overall fit of the model was acceptable(χ²=579.7(df=264, P=0.00), GFI=0.935, NFI=0.949, CFI=0.956, RMR=0.040). The results supported 6 hypotheses except for

and

. First, competence and benevolence were positively related to satisfaction, while integrity was not significant. A key result of the analysis was that benevolence has the strongest effect on satisfaction. Second, satisfaction had a positive impact on commitment and positive WOM but didn't significantly affect negative WOM. Third, commitment significantly enhanced positive WOM and reduced negative WOM. Conclusions - This study emphasizes the role of faculty trustworthiness based on a long-term relationship. And the findings suggest that the dimensions of faculty trustworthiness have differing effects on satisfaction. In particular, benevolence is found to be the most important factor. This study provides university managers with the following managerial implications. In order to increase the satisfaction of the students, university managers should focus on the faculty's competence and benevolence. Also, it is important that university managers take a relationship approach to maximize WOM effect.

• The KIPS Transactions:PartD
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• v.13D no.5 s.108
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• pp.717-724
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• 2006

The cost estimation of software is getting more important as the portion of software is increasing in acquiring weapon systems. However, the cost estimation of embedded software in a weapon system follows the cost estimation method for general purpose softwares and uses the PRICE S model as a tool. However, any validation result of the estimated cost through an evaluated software size is not well known. Hence, we propose an approach to estimate the cost through evaluating the embedded software site in weapon systems. In order to achieve our research goal, we evaluate the software size of using the line of codes and function points which are produced by the PRICE S model. Finally, we compare the estimated cost data the actual cost data provided by the production company. As a result, we propose an approach to estimate the size and the cost of embedded software in weapon systems which are not easy to estimate objectively. We also expect that the Proposed approach is used for the cost validation and negotiation in the acquisition of weapon systems in the future.

• (The) Korean Journal of Advertising
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• v.28 no.6
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• pp.7-34
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• 2017

The debate surrounding advertising effectiveness is not to be overstated as a major source of advertising research. However, there is still a lack of discussion on the model for measuring the effects of government and public service advertising. This study focuses on this point and develops an index model that can evaluate government advertising. For this purpose, we conducted a survey of 800 respondents in 7 major cities. Based on the creativity evaluation factors (originality, clarity, and appropriateness) of government advertising and the evaluation factors (interest, avoidance, and relevance) of policy contents, a causal model that affects the cognition, attitude, and behavioral responses of the audience was set up. As a result of analysis, originality, clarity, interest, and relevance except for appropriateness and avoidance were meaningful variables for creating government advertising effect such as policy understanding, audience attitude, word of mouth intention of policy. In addition, policy understanding and audience attitude were the main mediating variable influencing the word of mouth intention of policy. Based on research results, this paper discussed the direction for creating effective government and public service advertising in the future.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1253-1260
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• 2022

This paper reports the control method for the core power of the China initiative Accelerator Driven System (CiADS) facility. In the CiADS facility, an intense external neutron source provided by a proton accelerator coupled to a spallation target is used to drive a sub-critical reactor. Without any control rod inside the sub-critical reactor, the core power is controlled by adjusting the proton beam intensity. In order to continuously change the beam intensity, an adjustable aperture is considered to be used at the Low Energy Beam Transport (LEBT) line of the accelerator. The aperture size is adjusted based on the Proportional Integral Derivative (PID) controllers, by comparing either the setting beam intensity or the setting core power with the measured value. To evaluate the proposed control method, a CiADS core model is built based on the point reactor kinetics model with six delayed neutron groups. The simulations based on the CiADS core model have indicated that the core power can be controlled stably by adjusting the aperture size. The response time in the adjustment of the core power depends mainly on the adjustment time of the beam intensity.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.1-12
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• 2022

Estuary reservoirs were artificial reservoir with seawalls built at the exit points of rivers. Although many water resources can be saved, it is difficult to manage due to the large influx of pollutants. To manage this, it is necessary to analyze watersheds and reservoirs through accurate modeling. Therefore, in this study, we linked the Hydrological Simulation Program-FORTRAN (HSPF), Environmental Fluid Dynamics Code (EFDC), and Water quality Analysis Simulation Program (WASP) models to simulate the hydrology and water quality of the watershed and the water level and quality of estuary lakes. As a result of applying the linked model in stream, R² 0.7 or more was satisfied for the watershed runoff except for one point. In addition, the water quality satisfies all within 15% of PBIAS. In reservoir, R² 0.72 was satisfied for water level and the water quality was within 15% of T-N and T-P. Through the modeling system, We applied upstream pollutant management scenarios to analyze changes in water quality in estuary reservoirs. Three pollution source management were applied as scenarios, the improvement of effluent water quality from the sewage treatment plant and the livestock waste treatment plant was effective in improving the quality of the reservoir water, while the artificial wetland had little effect. Water quality improvement was confirmed as a measure against upstream pollutants, but it was insufficient to achieve agricultural water quality, so additional reservoir management is required.