• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.1
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• pp.1-6
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• 2020

Fast service access involves keeping track of the location of mobile users, while they are moving around the mobile network for a satisfactory level of QoS (Quality of Service) in a cost-effective manner. The location databases are used to keep track of Mobile Terminals (MT) so that incoming calls can be directed to requested mobile terminals at all times. MT reporting cell system used in location management is to designate each cell in the network as a reporting cell or a non-reporting cell. Determination of an optimal number of reporting cells (or reporting cell configuration) for a given network is reporting cell planning (RCP) problem. This is a difficult combinatorial optimization problem which has an exponential complexity. We can see that a cell in a network is either a reporting cell or a non-reporting cell. Hence, for a given network with N cells, the number of possible solutions is 2^N. We propose a biogeography based optimization (BBO) for design of mobile station location management system in wireless communication network. The number and locations of reporting cells should be determined to balance the registration for location update and paging operations for search the mobile stations to minimize the cost of system. Experimental results show that our proposed BBO is a fairly effective and competitive approach with respect to solution quality for optimally designing location management system because BBO is suitable for combinatorial optimization and multi-functional problems.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.777-786
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• 1995

This paper describes several algorithms for technology mapping of logic functions into interesting and popular FPGAs that use look-up table memories. In order to improve the technology mapping for FPGA, some existing multi-level logic synthesis, decomposition reduction and packing techniques are analyzed and compared. And then new algorithms such as node-pair decomposition, merging fanin, unified reduction and multiple output decomposition which are used for combinational logic design, are proposed. The cost function is used to minimize the number of CLBs and edges of the network. The cost is a linear combination of each weight that is given by user. Finally we compare our new algorithm with previous logic design technique［8］. In an experimental comparison our algorithm requires 10% fewer CLB and nets than SIS-pga.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.179-185
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• 2017

The problem that occurred in the design/fabrication/testing of the wideband transmitting power amplifier for an embedded active SONAR (Sound Navigation and Ranging) system operating underwater was analyzed and the solution of the problem was proposed in this paper. Wideband acoustic SONAR systems had been developed in order to improve the underwater detection performance. The underwater acoustic transmission system had been also developed to achieve the wideband SONAR system. In this paper, the wideband acoustic transmission signal was generated using a 2 Level sawtooth type Class D PWM (Pulse Width Modulation) which was not complicated to implement. When the sonar signals having two or more frequencies were simultaneously generated, parasitic frequencies were added to the original signals by integer multiples of the frequency difference of the original signal. To cope with this problem, we proposed a way to remove the parasitic frequency from the source signal through modeling and simulation of the implemented power amplifier and PWM control hardware using MATLAB and Simulink.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1095-1101
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• 2012

This paper presents a design of a BLDC servo motor control system for the auto process of assembly and supply using DSP(Digital Signal Processor) controller and IGBT driver. The assembly and supply auto processing system needs torque, speed, position control of servo motor for variable action. This paper implements those servo control with vector control and space vector PWM(Pulse Width Modulation) technique. As CPU of controller, TMS320F240 DSP was adopted because it has PWM waveform generator, A/D converter, SPI(Serial Peripheral Interface) port and many input/output port etc. This control system consists of 3-level hierarchy structure that main host PC manages three sub DSP system which transfer downward command and are monitoring the states of end servo controllers. Each sub DSP system operates eight BLDC servo controllers which control BLDC motor using DSP and IPM. Between host system and sub DSP communicate with RS-422, between main processor and controller communicate with SPI port.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.782-789
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• 2018

Multi-Function Display (MFD) of Korean Utility Helicopter (KUH) displays image information(navigation, flight, topographical and maintenance information) delivered from Mission Computer (MC) during flight operation. The abnormal display of MFD such as flickering phenomenon was identified in the system development. It was solved by improving the shielding performance of the DVI cable and changing the DVI cable installation path at the first mass production. However, it was occurred again when the aircraft was operated for one or two years after delivery. It was also identified in the evaluation process of the derivative helicopters. Therefore, a comprehensive review of the aircraft system level has been performed to solve the problem of MFD malfunction at first and then a design improvement plan was derived by improving the DVI cable. In this paper, the causes of MFD anomalies are analyzed and also the process of design improvement are summarized. The validity of the improvement has been verified through the DVI cable assembly comparison test, SIL/ground/flight test.

• Korean Journal of Hydrosciences
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• v.7
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• pp.37-49
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• 1996

This study aims at suggesting an alternative to improve flood controling capacity according to the cument design criteria for the existing Soyanggang Multi-purpose Dam which was constructed 20 years ago as the largest dam in Korea. The peak inflow of the adopted probable maximum flood (PMF) at the time of construction was 13,500 $m^3$/s. However, the newly estimated peak inflow of the PMF is 18,000 $m^3$/s which is 1.34 times bigger than the original one. This is considered to be due to the accumulation of the reliable flood and storm event records after construction, and due to the increasing tendency of the local flood peaks according to the influence of world-wide weather change. The new estimation of the probable maximum precipitation (PMP) was based on the hydro-meteorological method suggested by the guideline of the World Meteorological Organization (WMO). The unit hydrograph which was applied for the estimation of PMF was derived through linear programming algorithm by minimizing the sum of absolute deviations of the calculated and recorded flood hydrographs. In order to adopt the newly estimated PMF as a design flood, following four alternatives were compared : (1) allocation of more flood control space by lowering the normal high water level, (2) construction of a new spillway in addition to the existing spillway, (3) construction of a new dam which has relevant flood control storage at the upstream of the Soyanggang dam, (4) raising the existing dam crest. The preliminary evaluation of these alternatives resulted in that the second alternative is most economic and feasible. So as to stably cope with the newly estimated PMF by meeting all the current functions of the multipurpose dam, a detailed study of an additional spillway tunnel has to be followed.

• The Journal of Sustainable Design and Educational Environment Research
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• v.17 no.3
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• pp.35-45
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• 2018

The purpose of this study is to analyze the types of present situation data related to school facilities through existing literature and related systems and to develop indicators related to improvement of educational environment that can have an important influence on students' education and life in general. In this study, we conducted a second Delphy Survey to establish the educational environment improvement index. As a result, a total of 88 education environment improvement indicators were set, including 43 indicators on the quantitative aspects of the area, adequacy of general classrooms, and appropriateness of multi-purpose steel sugar, 34 indicators on the qualitative aspects such as the level of seismic performance, age of fire facilities, aging of toilets, and aging of finishing materials, and 11 indicators on operational aspects such as energy usage and user satisfaction.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.1
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• pp.11-18
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• 2019

There is a growing demand for public rental housing since housing price increased rapidly and socially vulnerable people need more stable housing. The purpose of this study is to investigate housing evaluation (satisfaction), moving plan, and residential service according to the type of the public rental housing and the characteristics of the resident, and to suggest the development direction for comprehensive housing services including the community level. Data used for analysis in this study are from 2016 Seoul panel survey of public rental housing residents. A total of 3009 questionnaire from public rental households were collected in 2016 Seoul panel survey. In order to investigate housing requirements, we analyzed household characteristics, housing satisfaction, moving plans, welfare services, residential activities and community facilities, social environment. In this study, the difference of residential satisfaction, moving plan, and residential service according to the type of the public rental housing and the characteristics of the resident is analyzed to identify their housing demands. As a result, there were differences in residential satisfaction, moving plan, and residential service depending on type of public rental housing and characteristics of residents. Residents in public rental housing modified from the multi-family housing after purchase showed lower residential satisfaction, and higher intention for moving plan compared to residents living in other type of public rental housing. In the residential service, residents in permanent lease type have higher experience of housing service as well as demand on housing service. Especially single household, elderly household, female household, or household with handicapped person indicated higher demand for housing services.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.3
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• pp.464-480
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• 2022

With the steady development of Artificial Intelligence (AI), online stores are adopting chatbot services as virtual shopping assistants. This study proposes the concept of para-social presence to explore the undiscovered role of fashion chatbots' emotional and relational characteristics on service acceptance. Based on the Technology Acceptance Model (TAM), this study investigates the effect of a chatbot's para-social presence on service acceptance intention through consumers' beliefs. The web-based experiment was conducted on adult consumers who experienced chatbot services in an online shopping situation. A total of 247 responses were analyzed using confirmatory factor analysis, structural equation modeling, and multi-group SEM by AMOS 21.0 and SPSS 23.0. The findings illustrate that the chatbot's intimacy positively influenced consumers' perceived enjoyment, while the chatbot's understanding had a significant effect on perceived usefulness and ease of use. The chatbot's involvement had a positive effect on all consumer beliefs. Moreover, perceived ease of use had a positive influence on usefulness. A greater level of perceived usefulness and enjoyment positively heightened consumers' service acceptance intention. This study also verifies the moderating role of a need for human interaction. Consumers with a high need for human interaction have a relatively low tendency to perceive chatbot services as useful.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.4
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• pp.699-707
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• 2023

DevSecOps is a concept that adds security procedures to the operational procedures of DevOps to respond to the short development and operation cycle. Multi-step vulnerability scanning process should be considered to provide reliable security while supporting rapid development and deployment cycle in DevSecOps. Many open-source vulnerability scanning tools available can be used for each stage of scanning, but there are difficulties in evaluating the security level and identifying the importance of information in integrated operation due to the various functions supported by the tools and different security results. This paper proposes an integrated security metric design plan for scurity results and the combination of open-source scanning tools that can be used in security stage when building the open-source based DevSecOps system.