• Advances in Computational Design
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• v.3 no.4
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• pp.367-384
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• 2018

The consideration of constructability issues at the design stage can lead to improved construction performance with smooth project delivery and savings in time and money. Empirical studies demonstrate the value obtained by integrating construction knowledge with the building design process, and its benefits for owners, contractors and designers. However, it is still a challenge to implement the concept into current design practice. There is a need for a decision support tool to aid designers in reviewing their design constructability, deploying current technological tools, such as BIM. Such tools are beneficial at the conceptual design stage when there is a room to improve the design significantly with less incurred cost. This research investigates how current process- and object-oriented models can be used to assess design constructability. It proposes a BIM-based model using embedded information within the design environment to conduct the assessment. The modelling framework is demonstrated in four key parts; namely, the conceptual design model, the constructability assessment model, the assessment process model and the decision-making phase. Each is associated with a set of components and functions that contribute towards the targeted constructability assessment outcomes. The proposed framework is the first to combine a numerical assessment system and a rule-based system, allowing for both quantitative and qualitative approaches. The modelling framework and its implementation through a prototype are described in this paper. It is believed that this framework is the first to enable users to transfer their construction knowledge and experience directly into a design platform linked to BIM models. The assessment criteria can be customised by the users who can reflect their own constructability preferences into various specialised profiles that can be added to the constructability assessment model. It also allows for the integration of the assessment process with the design phase, facilitating the optimisation of constructability performance from the early design stage.

• Journal of Korea Multimedia Society
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• v.14 no.10
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• pp.1335-1347
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• 2011

The dissemination and use of mobile applications have been rapidly expanding these days. And in such a situation, the security of mobile applications has emerged as a new issue. Although the safety of general software such as desktop and enterprise software is systematically achieved from the development phase to the verification phase through secure coding, there have been not sufficient studies on the safety of mobile applications yet. This paper deals with deriving weakness enumeration specialized in mobile applications and implementing a tool that can automatically analyze the derived weakness. Deriving the weakness enumeration can be achieved based on CWE(Common Weakness Enumeration) and CERT(Computer Emergency Response Team) relating to the event-driven method that is generally used in developing mobile applications. The analysis tool uses the dynamic tests to check whether there are specified vulnerabilities in the source code of mobile applications. Moreover, the derived vulnerability could be used as a guidebook for programmers to develop mobile applications.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.83-92
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• 2005

The purpose of the paper is to analyze an effectiveness before and after implementation of the median arterial bus lanes operation. The paper includes a speed analysis based on the Downs-Thomson Paradox theory, and a reliability analysis based on variance analysis of arrival time. According to the speed analysis, some road sections are now under phase 2 according to the Downs-Thomson Paradox, which is a state in which the bus speeds are greater than the car speeds. In the future it is predicted that cars and buses will reach an equilibrium speed which is in phase 3 of the multi-modal equilibrium theory. According to the reliability analysis of arrival time at each bus stop, in roads of median arterial bus lanes. the variance of arrival time is generally smaller than after the scheme implemented in eight months later.

• Journal of the military operations research society of Korea
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• v.36 no.2
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• pp.53-69
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• 2010

The long-term purpose of Military Acquisition Program Management (MAPM) is to fulfill requested performance, budget, and timing of military capability building. The Defense Acquisition Program Administration was established in 2006 and it adopted Integrated Control System. Moreover, there have no much studies done to examine the condition of Defense Capability Improvement Project in Korea through an empirical research although there are sixty one organizations are operating currently under Defense Capability Improvement Project. The objective of this study is to recognize Military Acquisition Program Management as a single project and to critically review relationship between Critical Success Factors (CSF) and Military Acquisition Program Management. Accordingly, three determinants to lead to successful Military Acquisition Program Management are "Communication" "User Participation" and "User Requirement." This study also demonstrates that Critical Success Factors have distinctive influences on successful Military Acquisition Program Management based on characteristic, size and phase of project. In retrospect, it is meaningful that Integrated Project Team (IPT) could classify priority of management according to characteristic, size and phase of project in the course of implementation.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.1
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• pp.23-28
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• 2016

In this paper, a Multi-Band Ku-band down converter was designed for reception of multi-band digital satellite broadcasting. The Multi-band low-nose down converter was designed to form four local oscillator frequencies (9.75, 10, 10.75 and 11.3GHz) representing a low phase noise due to VCO-PLL with respect to input signals of 10.7 to 12.75GHz and 3-stage low noise amplifier circuit by broadband noise matching, and to select an one band of intermediate frequency (IF) channels by digital control. The developed low-noise downconverter exhibited the full conversion gain of 64dB, and the noise figure of low-noise amplifier was 0.7dB, the P1dB of output signal 15dBm, and the phase noise -73dBc@100Hz at the band 1 carrier frequency of 9.75GHz. The low noise block downconverter (LNB) for receiving four-band digital satellite broadcasting designed in this paper can be used for satellite broadcasting of vessels navigating international waters.

• The Journal of Korean Association of Computer Education
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• v.11 no.4
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• pp.71-83
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• 2008

The recent advances of the information technology have motivated lots of research efforts to develop new computer-aided teaching and learning methodologies on various computer science topics, such as data structures, operating system, computer networks, and computer architecture. However, there have been only few studies to educate the database subject although it is one of the most important topics in the computer science. Specifically, among the various issues in the database subject, a learner often suffers to understand the mechanism of the concurrency control and recovery of database transaction in the database because it highly interacts with other functions in the database. Obviously, an intelligent visualization tool can help a learner to understand the process of the concurrency control and the recovery of database transaction. The purpose of this study is to develop an efficient visualization tool which can help users understand the two phase locking protocol (2PLP)-based concurrency control. Specifically, this visualization tool is designed to encourage a users' participation and raise their interest by visualizing the process of transactions and allowing users to specify and manipulate their own transactions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.668-674
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• 2009

In this paper, we design and implement a high speed power-line communication modem, supported up to the transmission rate of 480kbps in a lower frequency band of under 450kHz. The power-line channel model is discussed in the sense of the lower frequency band, and the transmission technique of OFDM(Orthogonal Frequency Division Multiplexing) is considered to improve the throughput effectively. According to the power-line channel variation, the designed modem can select the modulation mapping between a 16-QAM(Quadrature Amplitude Modulation) or a QPSK(Quadrature Phase Shift Keying). Thus, it makes a sufficient QoS even in a poor channel environments. With a implementation result, we show that it gives a variable transmission rate of 480kbps or 240kbps in the signal bandwidth of $50kHz{\sim}450kHz$.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.3
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• pp.163-170
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• 2008

Switching characteristics in both linear and nonlinear loads are analysed for a 3-phase voltage disturbance generator applicable to the performance test of custom power devices. Since the line current of the linear load is continuous the natural commutation of the SCR thyristors comprising the generator is carried out with ease. However, in case of nonlinear load the natural commutation scheme is different from that of the linear load due to the discontinuous load current. Through the analysis it is found that a specific switching condition can provide the voltage sag, swell, outage, and voltage unbalance generation in nonlinear load too. The operation of the voltage disturbance generation is described and the usefulness of the generator is verified through simulation and experimental results. It is expected that the generator can be used in the performance test of the custom power devices with low implementation cost and easy control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7C
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• pp.713-724
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• 2006

The purpose of this study is to design, implement and verify the pre-modulation filter with the variable -3dB cutoff frequency and linear phase response for bandlimiting the allocation of radio frequency bandwidth for PCM/FM transmission. For the design of this required filter, the digital FIR filter, DAC system and tuneable 2nd order LPF have been constructed and simulated according to the attenuation characteristic requirement of the amplitude frequency response by each stage. From these results, we have implemented the filter and verified the analog conversion hardware part which is composed of DAC system and tuneable 2nd order LPF for the interpolation of the discrete sequences. Especially this paper proposes and carries out the verification processes using the tone generator and the calibration procedures for more precise frequency response of the filter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.2
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• pp.77-85
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• 2014

Recently, utilization of MIMO(Multi-Input Multi-Output) system using array antennas is evaluated significantly according to the extension of high-capacity and high-speed communication services. However, MIMO system has disadvantages such as high-complexity and high-power-consumption, because RF(Radio Frequency) chain is required as antenna number, and several array antenna is used in conventional MIMO system. In order to solve these problems, research about beamspace MIMO system using ESPAR(Electronically Steerable Parasitic Array Radiator) antenna that has single RF chain by using one active antenna and several parasitic elements has been studied actively. Beamspace MIMO system using ESPAR antenna is possible to solve the problems of conventional MIMO system, because this system is composed by single RF chain. In this paper, in order to improve the system security, chaos communication algorithm that has characteristics such as non-periodic, non-predictability, easy implementation and initial condition is applied to QPSK (Quadrature Phase Shift Keying) modulated beamspace MIMO system. We design the chaos QPSK modulated beamspace MIMO system, and evaluate SER performance of this system.