• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1174-1180
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• 2011

Field Programmable Gate Array(FPGA)s are replacing traditional integrated circuits for space applications due to their lower development cost as well as reconfigurability. However, they are very sensitive to single event upset (SEU) caused by space radiation environment. In order to mitigate the SEU, on-board computer of STSAT-3 employed a triple modular redundancy(TMR) and scrubbing scheme. Experimental results showed that upset threshold energy was improved from 10.6 MeV to 20.3 MeV when the TMR and the scrubbing were applied to the on-board computer. Combining the experimental results with the orbit simulation results, calculated bit-flip rate of on-board computer is 1.23 bit-flips/day assuming in the worst case of STSAT-3 orbit.

• Journal of Power Electronics
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• v.13 no.4
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• pp.679-691
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• 2013

High-power electromagnetic transmitter power supplies are an important part of deep geophysical exploration equipment. This is especially true in complex environments, where the ability to produce a highly accurate and stable output and safety through redundancy have become the key issues in the design of high-power electromagnetic transmitter power supplies. To solve these issues, a high-frequency switching power cascade based emission power supply is designed. By combining the circuit averaged model and the equivalent controlled source method, a modular mathematical model is established with the on-state loss and transformer induction loss being taken into account. A triple-loop control including an inner current loop, an outer voltage loop and a load current forward feedback, and a digitalized voltage/current sharing control method are proposed for the realization of the rapid, stable and highly accurate output of the system. By using a new algorithm referred to as GAPSO, which integrates a genetic algorithm and a particle swarm algorithm, the parameters of the controller are tuned. A multi-module cascade helps to achieve system redundancy. A simulation analysis of the open-loop system proves the accuracy of the established system and provides a better reflection of the characteristics of the power supply. A parameter tuning simulation proves the effectiveness of the GAPSO algorithm. A closed-loop simulation of the system and field geological exploration experiments demonstrate the effectiveness of the control method. This ensures both the system's excellent stability and the output's accuracy. It also ensures the accuracy of the established mathematical model as well as its ability to meet the requirements of practical field deep exploration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.954-961
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• 2011

To apply Wi-Fi technique to the Broadcast field, we have to study features of IEEE 802.11 Broadcast packet. IEEE 802.11 Broadcast technique cannot guarantee successful packet delivery than IEEE 802.11 Unicast. A promising solution to this problem is the use of FEC(Forward Error Correction) mechanisms. However, the adjustment of the FEC redundancy rate is not a trivial issue due to the dynamic wireless environment. In order to explore the above issues we conducted an experimental study of the packet loss behavior of the IEEE 802.11g protocol. In order to study, we implemented a broadcast test bed. Based on the experimental results, we provide guidelines on wireless lan parameters(packet size, transmission rate(11g), background traffic). From this experimental study, we provide FEC redundancy rate.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.2
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• pp.10-18
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• 1988

In the three-dimensional analysis and deformation analysis of large structures, efficient is the use of the multiple method of close range photogrammetry which approaches the object distance. This study analyzes the influence of errors according to the overlap, the control points, and the object distance, to solve the problems which are raised in the multiple method. A wall-board, 7 meters by 3 meters, was used as a test field on which a total of 225 unknown points were equally disposed. The photographs with changing the overlap and object distance were taken by P-31 camera system. a total of 143 negatives are used in this study for computing 3-dimensional coordinates and its standard errors, and bundle adjustment of strips and blocks developed with on-line system is applied. In case of decreasing the number of control points, simulation error increases but actual error decreases and increases again. Due to the changed of object distances Z error represents largely compared to X, Y error, but good results in Z can be obtained by increasing the redundancy. And simulation error or actual error shows best results at the endlap of about 70%. To sum up this study, approprate arrangement of control points and overlap is meaningful, and multiple method by short object distance will be widely used to precision and deformation analysis of critical structures.

• Korean Journal of Environment and Ecology
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• v.22 no.1
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• pp.43-58
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• 2008

For this study, which was conducted in the summer from $2004\sim2007$, 10 small and medium sized streams in Korea were selected(Munsan and Gokreung Stream in the Han River watershed, Mi, Ssanggye and Nam Stream in the Nakdong River watershed, Gapeong and Jojong Stream in the Bukhan River watershed, Cheongmi, Yanghwa and Bokha Stream in the Namhan River watershed), and plant surveys were performed using the belt transect method on the most natural 1km sections of each stream in order to clarify the natural environment condition of the plants in each stream. In the results of the plant survey, the total number of plant species recorded was 296. After selecting 121 species of those surveyed plant in order of frequency, an RDA(Redundancy Analysis) and a Pearson Correlation Analysis were performed to determine the correlation between the selected plant species and environmental factors( such as distance from channel, size of bed material, number of bars, altitude, bed slope, width of channel, and measured data of water quality) of the study sites. There was no significant correlation between the 121 plant species and altitude, bed slope, and number of bars at the research sites, but the correlation of plant species with size of bed material, width of channel, electrical conductivity, and phosphate$(PO_4-P)$ concentration was from very high to moderate. Also, the spectrum of these plant species reflects the actual environmental conditions so the method used in the study seems to be correct, but owing to the range of diversity, the results of the study seem to be difficult to extend to other streams. Nevertheless, it is expected that this data can be used as a basic material for researching plants by stream characteristics or in selecting plant species for streams.

• Journal of Internet Computing and Services
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• v.22 no.2
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• pp.89-107
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• 2021

This paper explores the empirically analyzes the competitive nature of the five social media by analyzing the proper SNS service such as Facebook, Instagram, YouTube, Pinterest, and Twitter. In this study, we surveyed the use and satisfaction of social media for SNS users by using the proper theory. A total of 224 users were selected for analysis. Based on the results of the questionnaire, factor analysis was carried out to extract common factors such as relationship, sociality, convenience, daily life, and entertainment. As a result of the research using proper analysis, Facebook showed the widest narrowness in sociality (.627) and convenience (.636) in the first place, and YouTube showed the lowest in daily life (.670) and entertainment (.615) In the relationship (.520), the Instagram was the widest. In terms of five factors, Facebook and YouTube have the greatest overlap in relationship (1.826) and sociality (2.696), while Pinterest and Twitter are the most common in daily life (1.937) and entertainment (2.263) There is redundancy, and for convenience (2.583), YouTube and Twitter have the most redundancy. Facebook, Instagram, and YouTube have a competitive advantage over Pinterest in terms of relationships, sociality, convenience, routine, and entertainment, and are competitive across all factors except Facebook, Instagram, and YouTube Twitter It is possible to confirm that it is superior.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3194-3216
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• 2018

Slow Feature Discriminant Analysis (SFDA) is a supervised feature extraction method inspired by biological mechanism. In this paper, a novel method called Two Dimensional Slow Feature Discriminant Analysis via $L_{2,1}$ norm minimization ($2DSFDA-L_{2,1}$) is proposed. $2DSFDA-L_{2,1}$ integrates $L_{2,1}$ norm regularization and 2D statically uncorrelated constraint to extract discriminant feature. First, $L_{2,1}$ norm regularization can promote the projection matrix row-sparsity, which makes the feature selection and subspace learning simultaneously. Second, uncorrelated features of minimum redundancy are effective for classification. We define 2D statistically uncorrelated model that each row (or column) are independent. Third, we provide a feasible solution by transforming the proposed $L_{2,1}$ nonlinear model into a linear regression type. Additionally, $2DSFDA-L_{2,1}$ is extended to a bilateral projection version called $BSFDA-L_{2,1}$. The advantage of $BSFDA-L_{2,1}$ is that an image can be represented with much less coefficients. Experimental results on three face databases demonstrate that the proposed $2DSFDA-L_{2,1}/BSFDA-L_{2,1}$ can obtain competitive performance.

• Computers and Concrete
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• v.17 no.5
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• pp.579-596
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• 2016

This paper describes a method of the refined plastic hinge approach in the framework of the higher-order element formulation that can efficaciously evaluate the limit state capacity of a whole reinforced concrete structural system using least number of element(s), whereas the traditional design of a reinforced concrete structure (i.e. AS3600; Eurocode 2) is member-based approach. Hence, in regard to the material nonlinearities, the efficient and economical cross-section analysis is provided to evaluate the element section capacity of non-uniform and arbitrary concrete section subjected to the interaction effects, which is helpful to formulate the refined plastic hinge method. In regard to the geometric nonlinearities, this paper relies on the higher-order element formulation with element load effect. Eventually, the load redistribution can be considered and make full use of the strength reserved owing to the redundancy of an indeterminate structure. And it is particularly true for the performance-based design of a structure under the extreme loads, while the uncertainty of the extreme load is great that the true behaviour of a whole structural system is important for the economical design approach, which is great superiority over the conservative optimal strength of an individual and isolated member based on traditional design (i.e. AS3600; Eurocode 2).

• The Journal of Asian Finance, Economics and Business
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• v.5 no.3
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• pp.179-183
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• 2018

This study aims to explore the relationship between organizational justice and social loafing of organizations in Ho Chi Minh City through quantitative analysis from the survey data for the 228 employees are working at the Organizations in Ho Chi Minh City. The instrument of collecting data was a questionnaire. The collected data were analyzed using SPSS version 22 and employing exploratory factor analysis (EFA), Cronbach's alpha, multiple regression analysis. The results showed that only two factors are Distributive justice and Procedural justice is to have the reverse effect on social loafing of employee. From the results of the study showed, Distributive justice and Procedural justice has the opposite effect of social loafing, which demonstrates that when individuals feel that their work is spent on Perform tasks in a clearly divided and they will receive a worthwhile result in the group when performing the task then the individual's collective indifference to the organization will decrease. And motivate the employee to make more efforts to work and contribute for the organization. In addition, the factor of Procedural justice also has the opposite effect of collective redundancy, which demonstrates that employees are more concerned about fairness in official policies and organizational procedures.

• Korean Journal of Construction Engineering and Management
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• v.2 no.4 s.8
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• pp.48-61
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• 2001

This study aims at improving work reliability. It proposes a way to overcome the limitations of current scheduling methods by providing a new framework, CPAM(Construction Process Analysis Model) based on the lean principles. It suggests methods which improve work reliability and production effectiveness with variability control methods. Also it suggests methods which reduce inventories of materials and equipment and WIP(Work In Process) using two techniques; Lookahead Schedule and Weekly Work Plan. The contribution of this research also includes that it assumes planning as a process of reducing uncertainty and maximizing throughput, counter-posing plan reliability to resource redundancy as alternative strategies for managing in conditions of uncertain work flow.