• Advances in robotics research
• /
• v.2 no.2
• /
• pp.161-182
• /
• 2018

This paper proposes a novel receding horizon control (RHC) algorithm for formation control of a swarm of unmanned surface vehicles (USVs) using particle swarm optimization (PSO). The proposed control algorithm provides the coordinated path tracking of multi-agent USVs while preventing collisions and considering external disturbances such as ocean currents. A three degrees-of-freedom kinematic model of the USV is used for the RHC with guaranteed stability and convergence by incorporating a sequential Monte Carlo (SMC)-based particle initialization. An ocean current model-based estimator is designed to compensate for the effect of ocean currents on the USVs. This method is compared with the PSO-based RHC algorithms to demonstrate the performance of the formation control and the collision avoidance in the presence of ocean currents through numerical simulations.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.22 no.3
• /
• pp.37-58
• /
• 1997

An AI approach with tabu search is designed to solve multi-level knapsack problems. The approach performs intelligent actions with memories of historic data and learning effect. These action are developed ont only by observing the attributes of the optimal solution, the solution space, and its corresponding path to the optimal, but also by applying human intelligence, experience, and intuition with respect to the search strategies. The approach intensifies, or diversifies the search process appropriately in time and space. In order to create a good neighborhood structure, this approach uses two powerful choice rules that emphasize the impact of candidate variables on the current solution with respect to their profit contribution. "Pseudo moves", similar to "aspirations", support these choice rules during the evaluation process. For the purpose of visiting as many relevant points as possible, strategic oscillation between feasible and infeasible solutions around the boundary is applied. To avoid redundant moves, short-term (tabu-lists), intemediate-term (cycle-detection), and long-term (recording frequency and significant solutions for diversfication) memories are used. Test results show that among the 45 generated problems (these problems pose significant or insurmountable challenges to exact methods) the approach produces the optimal solutions in 39 cases.lutions in 39 cases.

• The Journal of the Korea Contents Association
• /
• v.12 no.5
• /
• pp.525-540
• /
• 2012

The purpose of the present study is to examine the causal relationship and invest the difference among isolation, interaction, content satisfaction, achievement and persistence in cyber university education by employment status. For this study, 104 students at A cyber university in Korea completed surveys in the fall semester of 2011. The result of this study indicated that there was a meaningful effect of interaction on isolation. Secondly, there was a meaningful effect of interaction on content satisfaction. Thirdly there was a meaningful effect of interaction on achievement. Lastly there were meaningful effects of isolation and interaction on persistence. In addition, according to multi-group analysis, there were no significant differences of structural path coefficients between two groups. Based on these results, this study suggests instructional design methods and management strategies to improve the quality of learning in cyber universities.

• Journal of Korea Technology Innovation Society
• /
• v.17 no.1
• /
• pp.146-173
• /
• 2014

Extant studies have explained that firm's innovations including technological product and process innovations contribute to its competitive advantage and growth, thereby supporting competitiveness and growth of industry. These studies, however, have focused mainly on the role and effect of technological change that is primarily measured by the patent numbers and R&D intensity. Aside from these traditional streams, there has been growing interest on the impact by various dimensions of innovation including non-technological innovations. Apart from the discussions on the dimensions and scope of innovation, stages or processes of innovation also have been studied. Extant studies on innovation process model, however, has limited its interests in the structure of the transformation of knowledge. This study have established a comprehensive model embracing operational and financial performance to investigate the causal paths between innovation and firm performance. Using multi-level generalized linear model with path analysis, this study have found results as follows: First, the processes from innovative activities to innovation output and outcomes including operational and financial performance at firm level were verified. Secondly, the influence of innovation decreases gradually as the distance away from the direct outputs of the innovation increase in the direction of financial outcomes. Third, the effect of innovation on the sales growth rate is higher for small businesses than for medium-sized businesses. The effect of innovation on the profit rate, however, is significant only for medium-sized businesses. For large businesses, innovation has no positive significant impact on any financial performance at all. Fourth, Fourth, the appropriability of innovation has positive impacts on innovative performance, patent applications, and operational performance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.8A
• /
• pp.741-747
• /
• 2011

Matrix Pencil method is one of the promising method to estimate DOA in non-stationary, multi-path coherent environment. Not only the Matrix Pencil Method offers better resolution than the conventional approach using covariance matrix, but also it is computationally very efficient. In this paper, we presented an effect of unbalanced data weighting in the formulation of the Matrix Pencil method. A new formulation has been suggested to mitigate the effect of unbalanced data weighting. Numerical simulation demonstrated that the proposed method can successfully eliminate the problem of unbalanced data weighting.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.35 no.7
• /
• pp.841-855
• /
• 2011

This study examines the structured model of building fashion customer loyalty by service recovery and scrutinizes the effect of explanations on perceived justice and the proposed model. The data of a total of 300 women were collected through an online survey. Employing structural equation modeling, this study demonstrated that both distributive and interactional justice had a positive impact on customers' satisfaction with service encounter that subsequently led to overall satisfaction with the brand. Overall satisfaction influenced the attitudinal loyalty of customers that induced their behavioral loyalty. To examine the effect of explanations on perceived justice and the process of building fashion customer loyalty by service recovery, t-test and multi-group SEM were employed. The result displayed that the group who received explanations after service failure perceived higher level of justice than the one who did not. There was a significant difference between two groups on the direct path from interactional justice to overall satisfaction with the brand. This study clarifies how perceived justice influences fashion customer loyalty mediating by satisfaction in and confirms the critical role of explanations in service recovery context. By implying the understanding of the important role of explanations in service recovery context, this study provides fashion marketers with insight for delivering more successful service recovery strategies that enhance customer loyalty.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.48 no.1
• /
• pp.37-49
• /
• 2024

This study confirmed the relationship between variables developed by qualitative ground theory through quantitative research. The purpose of the study is to explain the effect of core sales tasks on sales services and the mediating effect of organizational member relationships on sales services. The data were collected through a survey of fashion brand salespeople in Gwangju from September to October 2020 with data from 235 responses analyzed using SPSS 27.0 and AMOS 26.0. The validity of the research model verified the confirmatory factor analysis and the research hypothesis was verified through path analysis and multi-mediated analysis of the structural model. The research results were as follows. First, sales management did not directly affect sales services, and customer management affected sales services. Second, a meaningful causal relationship was shown to exist between organizational member relationships and sales management, but organizational member relationships and customer management did not have a significant relationship. Third, the total and individual indirect effects of headquarters relations, colleague relations, and customer management were all statistically significant.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.11a
• /
• pp.101-105
• /
• 1999

Electronic Toll Collection(ETC) System makes the telecommunication possible between the Beacon and the On Board Unit(OBU) in vehicle at the highway. In this paper, the propagation path of microwave is modelled and the induced voltage of receiving antenna is analyzed numerically according to multi-path fading effort. In this modelling, we consider the weather condition, polarization and antenna radiation pattern. Also, we suggest the diversity technique in order to re duce the fading effect. In the result, the lading effort is reduced significantly in case of the vertical polarization at the rain condition. The circular polarization is the most desirable in this application. The antenna which has the high directivity, is also desirable. Using the space diversity technique at the Beaten, the fading effect is reduced as the distance increases between the Beacon and OBU. These results are presented at the graphs whose axes are related to the magnitude of received voltage(dB) and the distance of the beacon and a vehicle.

• International Journal of Human Ecology
• /
• v.13 no.2
• /
• pp.69-86
• /
• 2012

This study determined the influence of personality patterns on marital adjustments mediated by communication effectiveness for 298 international marriages in South Korea. The results are as follows: (a) The mediator effects of personality patterns and communication effectiveness on the marital adjustment of international marriages were found to be significant; in addition, a mediator path with marital adjustment as a dependent variable was verified. (b) The extroversion, agreeableness, and openness of husbands were found to have a positive effect on their communication and marital adjustment in regards to the personality patterns of international. (c) Conscientiousness was identified as the only factor that affects the marital adjustment of a wife in regards to personality patterns. The implications of this study will be discussed in the conclusion part.

• Proceedings of the IEEK Conference
• /
• 2001.09a
• /
• pp.305-308
• /
• 2001

We analyze mathematically a VSB (vestigial side-band) transceiver system for the Advanced Television Systems Committee (ATSC) digital television standard and extract a near-baseband equivalent VSB channel model. This model shows the multi-path fading effect of the quadrature component on the in-phase component. Also, we obtain a simplified model of the VSB transceiver system, which is represented by convolution of the transmission signal (before modulation) and the VSB channel. This simplified model is efficiently used for simulation of VSB systems to improve its performances, especially in an equalization part. Applying the DTV channel specifications tested by the Advanced Television Test Conter (ATTC) to the channel model, we obtain an equivalent VSB channel and show the equalization result by using the conventional derision-feedback equalize (DFE).