• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.249-257
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• 2022

In recent years, if we order food by easily accessing the online market with our smartphone, we can receive the product in a fresh state at dawn the next day. Cold chain is an industry that can create high added value because it has both the characteristics of general logistics and sensitivity to temperature. Based on the electrical specifications derived from the reefer container capacity requirement investigation, we proved that power supply to up to 33 reefer containers can be made by using three additional auxiliary power supplies which are applied for freight trains in Korea. In this paper, we conducted a research on a design of power supply system for freight train reefer container based on simulation as a basic research necessary for low-temperature distribution and cold chain construction based on the reefer container railroad. Consequently, the simulation was conducted using the three-phase inverter diagram in PSIM and the SVPWM (3-harmonic injection method) control technique, and it was verified that the required power voltage was satisfied with 622V_dc, which is lower than the input voltage of general SPWM of 718V_dc. The details of this paper could be used as a foundational study for constructing cold chains based on a reefer container dedicated to freight trains in the future.

• Geomechanics and Engineering
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• v.31 no.2
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• pp.129-147
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• 2022

The properties of soil are naturally highly variable and thus, to ensure proper safety and reliability, we need to test a large number of samples across the length and depth. In pile foundations, conducting field tests are highly expensive and the traditional empirical relations too have been proven to be poor in performance. The study proposes a state-of-art Particle Swarm Optimization (PSO) hybridized Artificial Neural Network (ANN), Extreme Learning Machine (ELM) and Adaptive Neuro Fuzzy Inference System (ANFIS); and comparative analysis of metaheuristic models (ANN-PSO, ELM-PSO, ANFIS-PSO) for prediction of bearing capacity of pile foundation trained and tested on dataset of nearly 300 dynamic pile tests from the literature. A novel ensemble model of three hybrid models is constructed to combine and enhance the predictions of the individual models effectively. The authenticity of the dataset is confirmed using descriptive statistics, correlation matrix and sensitivity analysis. Ram weight and diameter of pile are found to be most influential input parameter. The comparative analysis reveals that ANFIS-PSO is the best performing model in testing phase (R² = 0.85, RMSE = 0.01) while ELM-PSO performs best in training phase (R² = 0.88, RMSE = 0.08); while the ensemble provided overall best performance based on the rank score. The performance of ANN-PSO is least satisfactory compared to the other two models. The findings were confirmed using Taylor diagram, error matrix and uncertainty analysis. Based on the results ELM-PSO and ANFIS-PSO is proposed to be used for the prediction of bearing capacity of piles and ensemble learning method of joining the outputs of individual models should be encouraged. The study possesses the potential to assist geotechnical engineers in the design phase of civil engineering projects.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3286-3297
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• 2024

Traditional text-based system engineering, which has been used in the design and application of passive residual heat removal system (PRHRS) for lead-cooled fast reactors, is prone to several problems such as low development efficiency, long iteration cycles, and model ambiguity. This study aims to effectively address the abovementioned problems by adopting a model-based system engineering (MBSE) method, which has been preliminarily applied to meet the design requirements of a PRHRS. The design process has been implemented based on the preliminary design of the system architecture and consists of three stages: top-level requirement analysis, functional requirements analysis, and design requirements synthesis. The results of the top-level requirements analysis and the corresponding use case diagram can determine the requirements, top-level use cases, and scenario flow of the system. During the functional requirements analysis, the sequence, activity, and state machine diagrams are used to develop the system function model and provide early confirmation. By comparing these sequence diagrams, the requirements for omissions and inconsistencies can be effectively checked. In the design requirements synthesis stage, the Analytic Hierarchy Process is used to conduct preliminary trade-off calculations on the system architecture, after which a white box model is established during the system architecture design. Through these two steps, the analysis and design of the system architecture are ultimately achieved. The resulting system architecture ensures the consistency of the design requirements. Ultimately, a functional hazard analysis was conducted for a specific incident to validate case requirements and further refine the system architecture. Future research can further reduce the design risk, improve the design efficiency, and provide a practical reference for the design and optimization of PRHRS in digital lead-cooled fast reactors.

• Archives of Metallurgy and Materials
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• v.66 no.3
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• pp.695-698
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• 2021

Influence of Si addition on oxide layer growth of Al-6 mass%Mg alloys in molten state was investigated in this study. After melt holding for 24 h, the melt surface of only Si-free alloy became significantly bumpy, while no considerably oxidized surface was observed even with 1 mass%Si addition. There was no visible change on the appearance of melt surfaces with increasing Si content. As a result of compositional analysis on the melt samples between before and after melt holding, the Si-added alloys nearly maintained their Mg contents even after the melt holding for 24 h. On the other hand, the Mg content in the Si-free alloy showed a great reduction. The bumpy surface on Si-free alloy melt showed a large amount of pores and oxide clusters in its cross-section, while the Si-added alloy had no significantly grown oxide clusters on the surfaces. As a result of compositional analysis on the surfaces, the oxide clusters in Si-free alloy contained a great amount of Mg and oxygen. The oxide layer on the Si-added alloy was divided into Mg-rich and Mg-poor areas and contained certain amounts of Si. Such a mixed oxide layer containing Si would act as a protective layer during the melt holding for a long duration.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.4
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• pp.72-81
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• 2006

In this paper, we first define a total of 64 instructions that are considered to be essential and frequently used, construct a datapath diagram, determine the control sequence using a finite state machine, and implement an 8-bit microcontroller using FPGA in VHDL. In the past, only functional simulation results of a rudimentary microcontroller were reported, the microcontroller lacked interrupt handling capability, or it was not implemented in hardware. We have designed a self-contained 8-bit microcontroller such that it can perform data transfer, addition, and logical operations, as well as stack and external interrupt operations. Following timing simulation of the designed microcontroller, we implemented it in an FPGA and verified its operation successfully. The design and implementation has been done under the Altera MAX+PLUS II integrated development environment using the EP1K50TC144-3 chip. The maximum operating frequency, the total number of logic elements used, and the logic utilization were found to be 9.39 MHz, 2813, and 97%, respectively. The result can be used as a microcontroller IP, and as needs arise, the VHDL code can be modified accordingly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.4
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• pp.1-9
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• 1982

Variation of soil properties is studied by permeating injection of chemical grouts, such as cement type, water-glass type and acrylamide type, to the same soil samples with different densities. Moreover, injection tests using specially prepared equipments of 1.0 shot system and 1. 5 shot system are attempted to investigate permeating injection effects in highly compacted soil and in the presence of ground water. The main factor which causes the improvement of cut-off effect and shearing strength is the cohesion of soil. The strength in the loose state is fundamentally governed by the membrane cohesion, meanwhile, in the loose state is governed by the structural cohesion. Injection effects under the ground water flow is considerably decreased, and effective gelling ratio of approximate 45~80% is observed by variation of velocity and gel time, besides grading of injection materials has high relation with permeation and traveling length but has little relation with effective gelling ratio. Permeating injection effects, such as gelling scope, gelling strength in highly compaoted soil conditions can be confirmed by penetration resistance diagram and iso-strength curve.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.819-826
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• 2018

The generalized Hamming weight is one of the important parameters of the linear code. It determines the performance of the code when the linear codes are applied to a cryptographic system. In addition, when the block code is decoded by soft decision using the lattice diagram, it becomes a measure for evaluating the state complexity required for the implementation. In particular, a bit-parallel multiplier on finite fields based on trinomials have been studied. Cellular automata(CA) has superior randomness over LFSR due to its ability to update its state simultaneously by local interaction. In this paper, we deal with the efficient synthesis of the pseudo random number generator, which is one of the important factors in the design of effective cryptosystem. We analyze the property of the characteristic polynomial of the simple 90/150 transition rule block, and propose a synthesis algorithm of the reversible 90/150 CA corresponding to the trinomials $x^2^n+x^{2^n-1}+1$($n{\geq}2$) and the 90/150 reversible CA(RCA) corresponding to the maximum weight polynomial with $2^n$ degree by using this rule block.

• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.97-106
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• 2002

In 3GPP2 standard, MIP is used and a PDSN performs the function of FA to support macro mobility. When a MS is roaming from a PDSN area to another, the mobility supported is called macro mobility, while it is called micro mobility when a MS is roaming from a RN area to another in a PDSN area. Since a PDSN performs the function of FA in 3GPP2 standard, it is possible to support mobility but its mechanism is actually for supporting macro mobility, not for micro mobility, thus it is weak in processing fast and seamless handoff to support micro mobility. In this paper, we suggest the seamless handoff algorithm barred on multicast group mechanism to support micro mobility. Depending on the moving direction and velocity of a MS, the suggested algorithm constructs a multicast group of RNs on the forecasted MS's moving path, and maximally delays RNs'joining to a multicast group to increase the network efficiency. Moreover, to resolve the buffer overhead problem of the existent multicast scheme, the algorithm suggests that each RN buffers data only after the forecasted handoff time. To prove deadlock freeness and liveness of the algorithm. we use state transition diagrams, a Petri-net modeling and its reachability tree. Then, we evaluate the performance by simulation.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.985-994
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• 1995

In this paper, we propose two hot standby architectures which not only provide high system availability but also lose little data on fault occurrence. In order to evaluate the performance of the proposed hot standby architectures, the warm standby architecture. In order to evaluate the performance of the propose d hot standby architectures, the warm standby architecture which is made from the hot standby architecture by eliminating its synchronization unit is considered. After system unavailability for each architecture is computed by using the corresponding Markov state diagram, the results are compared and evaluated. As the results, in most cases, hot standby architectures have higher availability than warm standby architecture. Also, hot standby architecture with external synchronization unit always maintains a little higher availability than hot standby architecture with internal synchronization unit. Active set time and personnel recovery rate for each architecture have little effect on system availability. However, in the case that data recovery time is too long, system availabilities of hot standby architectures and warm standby architecture degrade rapidly. In this case, the performance degradation of hot standby architectures is severe, and system availabilities of hot standby architectures eventually become lower than system availability of warm standby architecture.

• Korean Journal of Construction Engineering and Management
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• v.13 no.4
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• pp.141-151
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• 2012

Infrastructure are the essential element in the country for they are the basic facilities forming the basis of economic activity. In Korea Infrastructure which are subject to the management of government are increasing annually, and subsequently the budget of maintenance costs is expected to rise significantly. For the effective management of the constructed and accumulated infrastructure, the integrated management of the future assets will be needed which includes the determination of the asset status, management subjects, and the location, the maintenance of their performance and state, and the prediction of the cost required to increase their useful lifetime. However, in the domestic cases the road facilities valuation has not been done systematically, and the preparation and research on this is scarce. Thus, the systematic procedure for the road facilities valuation is required. In this paper the following study was conducted to derive the reasonable asset valuation methods. First, the valuation methods was investigated and summarized throughout the domestic and international research literature. Second, to apply the investigated valuation methods to the road facilities the valuation process that reflects domestic conditions and characteristics has been developed. Third, a working Bridge, Highways, and General national ways were applied to the general valuation process, and the results were analyzed. As a final step a schematic diagram of the asset management support by WDRC valuation method was presented.