• ETRI Journal
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• v.43 no.3
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• pp.436-446
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• 2021

In this paper, we propose an energy-efficient unmanned aerial vehicle (UAV) relaying network. In this network, the channels between UAVs and ground transceivers are model-free. A UAV acting as a flying relay explores better channels to assist in efficient data delivery between two ground nodes. The full-duplex relaying mode is applied for potential energy efficiency (EE) improvements. With the genetic algorithm, we manage to optimize the UAV trajectory for any arbitrary radio map scenario. Numerical results demonstrate that compared to other schemes (eg, fixed trajectory/speed policies), the proposed algorithm performs better in terms of EE. Additionally, the impact of self-interference on average EE is also investigated.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.653-671
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• 2023

In practice, the interference influence caused by adjacent footings of structures on geo-reinforced loose soil has a considerable impact on their behavior. Thus, the goal of this study is to evaluate the behavior of two strip footings in close proximity on both geocell and geogrid reinforced soil with different reinforcement layers. Geocell was made from geogrid material used to compare the performance of cellular and planar reinforcement on the bearing pressure of twin footings. Extensive experimental tests have been performed to attain the optimum embedment depth and vertical distance between reinforcement layers. Particle image velocimetry (PIV) analysis has been conducted to monitor the deformation, tilting and movement of soil particles beneath and between twin footings. Results of tests and PIV technique were verified using finite element modeling (FEM) and the results of both PIV and FEM were used to utilize failure mechanisms and influenced shear strain around the loading region. The results show that the performance of twin footings on geocell-reinforced sand at allowable and ultimate settlement ranges are almost 4% and 25% greater than the same twin footings on the same geogrid-reinforced sand, respectively. By increasing the distance between twin footings, soil particle displacements become smaller than the settlement of the foundations.

• The Journal of Industrial Distribution & Business
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• v.14 no.4
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• pp.1-10
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• 2023

Purpose: This paper aims to investigate how self-regulatory focus (SRF) influences the relationship between perceived brand localness (PBL) and purchase intentions (PI). This research adopted both domestic and foreign-owned brands to examine the moderating effect of self-regulatory orientations and product types respectively to exclude the interference of brand origin. Research design, data, and methodology: This study surveyed Chinese consumers and collected data using social media applications. ANOVA analysis and PROCESS modeling were adopted to complete the empirical analysis. Results: This research demonstrates that brand origin does not inhibit the positive impact of PBL on purchase intentions regardless of whether it originates from mainland China or not. Study 1 proved that the effect of PBL on PI is more convincing among consumers with promotion focus orientations. In study 2, higher purchase intentions were found for hedonic perceived local brands among promotion-focused consumers while significant preferences were found for utilitarian perceived local brands among prevention-focused consumers. Conclusions: This research complements the literature about the potential psychological factors influencing PBL and contributes to marketers in developing effective marketing strategies and appropriate positioning decisions. Overall, this study has important theoretical and managerial contributions to international marketing, particularly in the context of the current recession.

• ETRI Journal
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• v.46 no.3
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• pp.446-460
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• 2024

In this paper, we mathematically investigate a downlink non-orthogonal multiple access (NOMA) system for short-packet communications (SPC) in which the near users are used as full-duplex (FD) relays to forward intended signals from the source to a far user. In addition, partial relay selection is employed to enhance the performance of the FD relays under the impact of imperfect interference cancellation. At the far user, selection combining (SC) or maximal ratio combining (MRC) is employed to combine the signals received from the source and the selected FD relay. The analytical expressions for the average block error rate (BLER) of two users over flat Rayleigh fading channels are derived. Furthermore, closed-form asymptotic expressions of the average BLERs at the near and far users in high signal-to-noise ratio (SNR) regimes are obtained. The numerical results show that the analytical BLERs of the near user and far user closely match the simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.272-278
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• 2015

This paper analyzed interference impact between wireless headset and Wireless Fidelity which get a high possibility of simultaneously operating in the Industry Science Medical(ISM) bands. Analysis methods of Minimum Coupling Loss(MCL) and Monte Carlo(MC) were applied by using the characters and parameters referenced to Institute of Electrical and Electronic Engineers(IEEE) 802.11b. The protection distance between interferer (WiFi transmitter) and victim (Wireless headset receiver) was calculated through the MCL. The protection distance was obtained for the case of single interferer, and the maximum allowable number of multiple interferers was computed according to the cell radius of a victim system to meet 5 % below of interference probability by using a statistical analysis based on the MC method. The analysis results are expected to be used as a guideline to coexist the wireless headset and low power devices in the ISM band.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.125-132
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• 2007

We estimated the distribution of predator-prey interaction strengths for 12 species of herbivores (including amphipods, isopods, gastropods, and sea urchins) and made a regression model that may be applicable to other species. Laboratory experiments were used to determine per capita grazing rate (PCGR; g seaweeds/individual/day). Relationship between the biomass of individual grazers and fourth-root transformed PCGR was fitted to power curve ($y=0.2310x^{0.3290}$, r=0.8864). This finding supported that the grazing efficiency was not even as individual grazers increase in size (biomass). Therefore, the biomass-normalized PCGR was estimated and revealed that smaller size herbivores were more effective grazers. Grazing impact considering density of each taxon was calculated. The sea hare Aplysia kurodai had greatest grazing impact on the seaweed bed and the sea urchin Strongylocentrotus nudus and S. intermedius were ranked in descending order of the impact. The amount of seaweed grazed by the amphipod Elasmopus sp. (>4,000 $ind./m^2$) and Jassa falcata (>2,000 $ind./m^2$) were 3.435 and $1.697mg/m^2/day$ respectively. The combined grazing amount of herbivores was $5,045mg/m^2/day$ in the seaweed bed. Although sea hare and sea urchin had strong impacts on seaweeds, the effects of dense, smaller species could not be seen as negligible. Surprisingly, the calculated grazing potential of sea urchins with a mean density of 3 $ind./m^2$ exceeded the mean production of seaweed cultured in domestic coastal waters in Korea (ca., 5 ton/ha). Small crustaceans were also expected to consume up to 16% of the seaweed production if their densities were rising under weak predation conditions. Considering that the population density of herbivores are strongly controlled by fish, human interference like overfishing may have strong negative effects on persistence of seaweeds communities.

• Korean Institute of Interior Design Journal
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• v.22 no.6
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• pp.98-107
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• 2013

Space evolves from the concept of deterministic static location to a dynamic, connected area through the interference of the user. While this does incorporate physical changes of the space, it also reflects the changes of the program or characteristics of the space through the actions and changes of the user. Therefore, in this study we plan to review the characteristic of time appearing within space, thereby discussing the impact of changing of condition in time-space to the decision making of the user. Further, we plan to analyze the specific causes, and subsequently introduce a new perspective over space. In order to achieve this, we need to first understand the reason why the attribute of time needs to be discussed in space, and perform a fundamental analysis of factors for the changes of the users' actions following changes in space-time condition. This means that space is not limited to merely satisfying its innate objective as an area, but may have a basis for modifying its role to help the decision making of the users caused by changes in space-time conditions. Accordingly, we analyze the factors for change of environment that can appear in space following the flow of time caused by correlation in space-time, as well as psychological factors and variables for decision making by the users. Based on this, we analyze cases to study the influence of condition changes in time-space on the action decision judgment of the users. Through this, we propose that the actions of the users can be determined following changes in time-space conditions, and discuss the need for changes in our perspective of space.

• Journal of Power Electronics
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• v.15 no.3
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• pp.621-633
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• 2015

This paper proposes the analysis and design of a DC-side symmetrical zero-current-switching (ZCS) Class-D current-source driven resonant rectifier to improve the low power-factor and high line current harmonic distortion of lighting applications. An analysis of the junction capacitance effect of Class-D ZCS rectifier diodes, which has a significant impact on line current harmonic distortion, is discussed in this paper. The design procedure is based on the principle of the symmetrical Class-D ZCS rectifier, which ensures more accurate results and provides a more systematic and feasible analysis methodology. Improvement in the power quality is achieved by using the output characteristics of the DC-side Class-D ZCS rectifier, which is inserted between the front-end bridge-rectifier and the bulk-filter capacitor. By using this symmetrical topology, the conduction angle of the bridge-rectifier diode current is increased and the low line harmonic distortion and power-factor near unity were naturally achieved. The peak and ripple values of the line current are also reduced, which allows for a reduced filter-inductor volume of the electromagnetic interference (EMI) filter. In addition, low-cost standard-recovery diodes can be employed as a bridge-rectifier. The validity of the theoretical analysis is confirmed by simulation and experimental results.

• Journal of Korean Society of Forest Science
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• v.64 no.1
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• pp.64-73
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• 1984

As data basic to policy in nature conservation, the Degree of Green Naturality (DGN) survey was usually carried out. This also explains the impact of human interference to natural environment. Gongju gun and Yeongi gun were surveyed in the summer of 1983 to determine the DGN of these districts. Then, the surveyed DGN was compared to the existing standard. The results obtained appeared that the average DGN of these districts ranged about 5.1 to 5.9 and especially the ratio of DGN 7-graded area was high. Because of difficulties in applying the existing standard directly to middle part of Korea, further improvement on the existing standard for ranking or surveying the DGN should be reconsidered.

• Journal of Urban Science
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• v.6 no.2
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• pp.29-34
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• 2017

Although the supply of public parking lots in major cities is steadily increasing, there is still a shortage of parking spaces that take into account the characteristics of actual available parking spaces. These parking problems are caused by conflicts between users, illegal occupation and privatization of roads, interference with traffic roads, and business stagnation in commercial areas and illegal parking problems. In addition, despite various parking demand management policies and continuous supply of public parking facilities, the solution to the parking problem is uneasy due to increased construction costs and changes in social conditions. In order to solve this problem, it was judged that it would be necessary to utilize the existing public parking lots efficiently. Therefore, we collect the variables expected to affect the turnover, and use multiple regression models. The results are summarized as follows. Firstly, public parking lots can be classified into four types using utilization rate and turnover rate. Secondly, influencing factors are found including index of public transportation usage convenience, index of illegal parking, and land use characteristics in central commercial district. Thirdly, it was shown that there was little impact by the size of public parking lots, separation distance to subway distance, separation distance to bus stops, transfer zone, residential zone, and second-rated lots by parking costs. Finally, it is found that public parking lots can be improved by proving accessibility of public transit, enforcement of illegal parking, active approaches supporting public parking lots. It is also recommended that public parking cost rating system based mainly on land use characteristics should be remedied and rearranged.