• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.127-141
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• 1996

This paper presents a unique approach to urban traffic network signal control. This paper begins with an introduction to traffic control in general, and then goes on to describe the approach of fuzzy control, where the signal timing parameters at a given intersection are adjusted as functions of the local traffic network condition and adjacent intersection. The signal timing parameters evolve dynamically using only local information to improve traffic signal flow. The signal timing at an intersection is defined by three parameters : cycle time, phase split, off set. Fuzzy decision rules are used to adjust three parameters based only on local information. The amount of change in the timing parameters during each cycle is limited to a small fraction of the current parameters to ensure smooth transition. In this paper the effectiveness of this method is showed through simulation of the traffic signal flow in a network of controlled intersection.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.2
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• pp.113-120
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• 2021

The Distance Measuring Equipment (DME) is a ground-based aircraft navigation system and is considered as an infrastructure that ensures resilient aircraft navigation capability during the event of a Global Navigation Satellite System (GNSS) outage. The main problem of DME as a GNSS back up is a poor positioning accuracy that often reaches over 100 m. In this paper, a novel approach of applying deep reinforcement learning to a DME pulse design is introduced to improve the DME distance measuring accuracy. This method is designed to develop multipath-resistant DME pulses that comply with current DME specifications. In the research, a Markov Decision Process (MDP) for DME pulse design is set using pulse shape requirements and a timing error. Based on the designed MDP, we created an Environment called PulseEnv, which allows the agent representing a DME pulse shape to explore continuous space using the Soft Actor Critical (SAC) reinforcement learning algorithm.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.8
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• pp.937-949
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• 1988

This paper proposes a code optimization algorithm for dealing with hazards which are occurred in pipelined architecture due to resource dependence between executed instructions. This algorithm solves timing hazard which results from resource conflict between concurrently executing instructions, and sequencing hazard due to the delay time for branch target decision by reconstructing of instruction sequence without pipeline interlock. The reconstructed codes can be generated efficiently by considering timing hazard and sequencing hazard simultaneously. And dynamic execution time of program is improved by considering structral hazard which can be existed when pipeline is controlled dynamically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.27-33
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• 2000

Gardner’s algorithm is one of the useful algorithm for NDD(Non-Decision Directed) symbol synchronization in PAM communications. But the algorithm has a weak point such as pattern noises increasing in multi-level PAM. To insert a pre-filter in the algorithm is able to reduce timing jitter and pattern noise. In this paper, we analyze statistical properties of NDD algorithm to find an optimal parameter of the pre-filter for improving timing jitter and PLL locking. As a simulation result, optimum value of pre-filter parameter, $\beta$, is 0.3 and 0.5 at the roll off factor of the channel, $\alpha$, is 0.5 and 1.0, respectively. Optimum parameters of the pre-filter for clock synchronization of all-digital 256-QAM demodulator is shown in the results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.237-244
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• 2003

This paper presents the design of a QPSK/16-QAM downstreams receiver chip. The proposed chip consists of a blind equalizer, a timing recovery block and a carrier recovery block. The blind equalizer uses a DFE sturucture using CMA(Constant Module Algorithm). The symbol timing recovery uses the modified parabolic interpolator. The decision-directed carrier recovery is used to remove the carrier frequency offset, phase offset and phase jitter. The implemented LMDS receiver can support four data rates, 10, 20, 30 and 40 Mbps and can accommodate the symbol rate up to 10 Mbaud. This symbol rate is faster than existing QAM receivers.

• Journal of Korean Institute of Industrial Engineers
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• v.32 no.3
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• pp.180-190
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• 2006

We evaluate the economic value and the optimal investment timing of IMT-2000 in Korea, in the perspective of a service provider who owns the business license for IMT-2000, by using the real options analysis. The result clearly shows the project value with options is positive and delaying the investment is more favorable to the provider. Binomial lattice approach, in which we try to describe American call option and sequential compound option, and sensitivity analysis present the optimal decisions according to future states and enable the management to make decision strategically and proactively.

• Journal of Industrial Technology
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• v.18
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• pp.309-316
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• 1998

The airbag system for automobile is one of the most important passenger protect system. And it is very important whether to inflate or not, and when the airbag will be inflated. This paper focuses on how to find airbag triggering time after the automobile is crashed. In this paper we present an algorithm for airbag triggering time decision and compare the triggering time with the time by the other algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.226-230
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• 2000

In this paper, we implemented the QPSK demodulator with a CPLD chip, and examined the results. DD(Decision Directed)-Gardner algorithm is used for STR loop and Decision-Directed algorithm is used for CPR loop. The speed of the QPSK demodulator implemented in FLEX10K chip can be guaranteed approximately 2[Mbpsl] transmission speed. In practical designed by ASIC, the speed is faster than that of CPLD by 5-6 times.

• Korean System Dynamics Review
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• v.5 no.1
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• pp.127-142
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• 2004

Feedback loop dominance is a key concept to understand structural driving forces of system behavior. In this paper, we propose two kinds of shifts in dominant feedback loops: continuous shifts (CS) and discrete shifts (DS). With the help of questionnaires, we verified three hypotheses regarding cognitive biases in perceiving the shifts in dominant feedback loops: 1) failure in perceiving continuous shifts, 2) tendency of decision making based on discrete shifts, and 3) different perception on the dominant feedback loops between level variables and rate variables. We discussed the implication of these cognitive biases on time delay and timing strategy in decision-making processes.

• Journal of Korea Trade
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• v.24 no.4
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• pp.71-94
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• 2020

Purpose - Multi-National Enterprises (MNEs) tend to face a high level of institutional pressures in regions with high institutional development level. When complying with institutional pressures, firms try to make decisions to maximize profit while minimizing the risks to them. The purpose of this study is to investigate the influence of the institutional development level on institutional compliance timing by MNEs and the relationship between compliance speed and corporate performance. Design/methodology - The research focuses on three main variables, which are the institutional development level (as a determination of the institutional pressure level), the firm's compliance speed (as a determination of the compliance timing), and the firm's financial performance (as a determination of the corporate performance). We collected 19,869 firm-level data from CSMAR (the China Stock Market and Accounting Research), 6,922 CSR data from RKS (the Rankins CSR Ratings), and province and city-level data from the NERIM (National Economic Research Institute Index of Marketization) and NBSC (National Bureau of Statistics of China). The firms in China were chosen for analysis, and the analysis period was from 2008 to 2017. Random Effects GLS Regression was used to test the relationships among the variables. Findings - This study examined the effect of the institutional development level on the firm's compliance speed, together with the effect of compliance speed on the firm's financial performance of the MNEs in China. We found that the institutional development level positively influenced firms' financial performances, which means the firms' financial performances are better in the region with a high institutional development level. The compliance speed of institutional practice by firms was faster in the higher level of institutional development. However, the firm's delayed compliance led to better financial performance. Originality/value - Studies in the resource dependence view of Institutional Theory often fall short in understanding the theory by overlooking the firm's active decision-making. Thus, the findings do not present a full scope of corporate performance in this regard. This study not only found a way to test the role of a firm's independent decision-making (i.e., compliance timing) when facing the institutional pressure but also prove the significant role of the compliance timing on corporate performance. Also, we were able to test the effect of institutional development level, controlling location-specific variables because we used CSR performance data for MNEs operating in China. Lastly, by doing the above, the findings of this study suggest practical implications to the industry practitioners in MNEs.