• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.1
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• pp.35-50
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• 2022

After the introduction of the central bus lane system, bus traffic was prioritized. This resulted in improved trust from bus users. However, the low capacity at the central bus stop reduces traffic speed and punctuality. In addition, physical constraints are inevitable because the construction of central bus lanes and bus stops considers the city's road geometry. Therefore, this study attempted to optimize the effective green time of the traffic signal system at the entrance and exit of the central bus stop to remedy its insufficient operational capacity. The Transit Capacity and Quality of Service Manual and Korea Highway Capacity Manual were used as the analysis methodologies. The number of stop areas for central bus stops to be built was determined by excluding variable physical factors, and field survey data collected from nine randomly selected central bus stops currently installed in Seoul were used. A scenario analysis was conducted on the central bus stops with insufficient capacity by adjusting the effective green time, and the capacity of the central bus stop was set as the dependent variable. According to the results, 26.7 percent of the central bus stops with insufficient capacity can solve the problem of insufficient capacity. Therefore, the results of this study can be verified by improving the operation level, and it can be effective even if the number of central bus stops calculated by engineering is not guaranteed during the planning stage of the central bus stop. As the number of central bus stops is expected to increase further as the number of central bus stops increases, it is necessary to improve the number of central bus stops. Therefore, it is hoped that the results presented in this study will be used as basic data for the improvement plan at the operational level before introducing the physical improvement plan.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.11
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• pp.471-480
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• 2023

The Korean construction order volume in South Korea grew significantly from 91.3 trillion won in public orders in 2013 to a total of 212 trillion won in 2021, particularly in the private sector. As the size of the domestic and overseas markets grew, the scale and complexity of EPC (Engineering, Procurement, Construction) projects increased, and risk management of project management and ITB (Invitation to Bid) documents became a critical issue. The time granted to actual construction companies in the bidding process following the EPC project award is not only limited, but also extremely challenging to review all the risk terms in the ITB document due to manpower and cost issues. Previous research attempted to categorize the risk terms in EPC contract documents and detect them based on AI, but there were limitations to practical use due to problems related to data, such as the limit of labeled data utilization and class imbalance. Therefore, this study aims to develop an AI model that can categorize the contract terms based on the FIDIC Yellow 2017(Federation Internationale Des Ingenieurs-Conseils Contract terms) standard in detail, rather than defining and classifying risk terms like previous research. A multi-text classification function is necessary because the contract terms that need to be reviewed in detail may vary depending on the scale and type of the project. To enhance the performance of the multi-text classification model, we developed the ELECTRA PLM (Pre-trained Language Model) capable of efficiently learning the context of text data from the pre-training stage, and conducted a four-step experiment to validate the performance of the model. As a result, the ensemble version of the self-developed ITB-ELECTRA model and Legal-BERT achieved the best performance with a weighted average F1-Score of 76% in the classification of 57 contract terms.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.559-567
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• 2012

A level set based topological shape optimization method for nonlinear structure considering hyper-elastic problems is developed. To relieve significant convergence difficulty in topology optimization of nonlinear structure due to inaccurate tangent stiffness which comes from material penalization of whole domain, explicit boundary for exact tangent stiffness is used by taking advantage of level set function for arbitrary boundary shape. For given arbitrary boundary which is represented by level set function, a Delaunay triangulation scheme is used for current structure discretization instead of using implicit fixed grid. The required velocity field in the actual domain to update the level set equation is determined from the descent direction of Lagrangian derived from optimality conditions. The velocity field outside the actual domain is determined through a velocity extension scheme based on the method suggested by Adalsteinsson and Sethian(1999). The topological derivatives are incorporated into the level set based framework to enable to create holes whenever and wherever necessary during the optimization.

• Journal of Broadcast Engineering
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• v.17 no.2
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• pp.207-222
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• 2012

Recently, many consumer electronics manufacturers have produced 3D devices such as 3DTVs and 3D monitors as interests in a stereoscopic video service are getting increased. However, most of 3D services are focused on local storage or bandwidth guaranteed service since 3D stereoscopic video service require bandwidth more stable and larger. This property causes difficulties in seamless stereoscopic video streaming services under IP based open network environment that cannot guarantee quality of services. In order to achieve a seamless video streaming service the international standard organization MPEG (Moving Pictures Experts Group) has developed the adaptive HTTP streaming technology called as DASH (Dynamic Adaptive Streaming over HTTP). However, the DASH doesn't have obvious scheme which can express the two elementary video streams based service-compatible stereoscopic contents in one segment. Therefore, this paper proposes a scheme of efficient 3D adaptive streaming service based on the DASH, which covers not only frame-packing stereoscopic contents but also service-compatible ones. The 3D adaptive HTTP streaming scheme introduced in this paper is able to provide 3D contents with various qualities to user and also has benefit that single 3D content can be applied to a variety of devices.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.87-93
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• 2009

Wireless mesh networks (WMNs) are emerging technologies that provide ubiquitous environments and wireless broadband access. The aggregate capacity of WMNs can be improved by minimizing the effect of channel interference. The IEEE 802.11b/g standard which is mainly used for the network interface technology in WMNs provides 3 multiple channels. We must consider the channel scanning delay and the channel dependency problem to effectively assign channels in like these multi-channel WMNs. This paper proposes a cluster-based channel assignment (CB-CA) algorithm for multi-channel WMNs to solve such problems. The CB-CA does not perform the channel scanning and the channel switching through assigning co-channel to the inter-cluster head (CH) links. In the CB-CA, the communication between the CH and cluster member (CM) nodes uses a channel has no effect on channels being used by the inter-CH links. Therefore, the CB-CA can minimize the interference within multi-channel environments. Our simulation results show that CB-CA can improve the performance of WMNs.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.256-264
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• 2012

The directional algebraic reconstruction technique (DART) using the trigonometric current pattern is one of the image reconstruction algorithms in electrical impedance tomography (EIT). This method needs to compute resistances between electrode pairs as using relation between the injected currents and measured voltages for the reconstruction of the inner image. The delay time is incurred in this process. Therefore this paper proposes modified directional algebraic reconstruction technique (mDART) using the adjacent current pattern instead of the trigonometric current pattern to solve the delay time for initial resistance values. The proposed method uses measured voltages instead of computed resistances in the reconstruction algorithm. Hence this method can eliminate the delay time because it does not use the resistances. In conclusion, the proposed method improves image quality and image reconstruction time by using the adjacent current pattern. To prove performance of the proposed method, we carried on computer simulation of various cases.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.128-138
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• 2010

In this paper, we propose a new bit assignment scheme for Wyner-Ziv video coding. Distributed video coding (DVC) is a new video coding paradigm which enables greatly low complexity encoding because it does not have any motion prediction module at encoder. Therefore, it is very well suited for many applications such as video communication, video surveillance, extremely low power consumption video coding, and other portable applications. Theoretically, the Wyner-Ziv video coding is proved to achieve the same rate-distortion (RD) performance comparable to that of the joint video coding. However, its RD performance has much gap compared to MC-DCT-based video coding such as H.264/AVC. Moreover, Transform Domain Wyner-Ziv (TDWZ) video coding which is a kind of DVC with transform module has difficulty of exact bit assignment because the entire image is treated as a same message. In this paper, we propose a feasible bit assignment algorithm using adaptive quantization matrix selection for the TDWZ video coding. The proposed method can calculate suitable bit amount for each region using the local characteristics of image. Simulation results show that the proposed method can enhance coding performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.4
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• pp.84-91
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• 2011

Recently, WBAN(Wireless Body Area Network) which has progressed standardization based on IEEE 802.15.6 standardization is a network for the purpose of the short-range wireless communications within around 3 meters from the inner or outer human body. Effective QoS control technique and data efficient management in limited bandwidth such as audio and video are important elements in terms of users and loads in short-range wireless networks. In this paper, for high-speed WBAN IEEE 802.15.6 standard, the dynamic allocation to give an efficient bandwidth management and weighted fair queueing algorithm have been proposed through the adjustment of the super-frame about limited data and Quality of Service (QoS) based on the queuing algorithm. Weighted Fair Queueing(WFQ) Algorithm represents the robust performance about elements to qualitative aspects as well as maintaining fairness and maximization of system performance. The performance results show that the dynamic allocation expanded transmission bandwidth five times and the weighted fair queueing increased maximum 24.3 % throughput and also resolved delay bound problem.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.551-564
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• 2012

The purpose of this study is to gain knowledge about the influence of running time of 3D stereoscopic video on audience perceptions. This study compares the influence of running time between 20 minutes and 40 minutes of 3D stereoscopic music shows on audience perceptions such as perceived characteristics, impression, presence, entertainment, fatigue and unnatural looking images. After experiment with 40 samples, the present research found that when people watched shorter 3D stereoscopic music video, they perceived more 3D functionality, such as depth, image conveyance and message conveyance. The results also suggest that people who watched shorter 3D stereoscopic video felt more impression such as definiteness and freshness from the 3D images. Moreover, the result confirm that when watching shorter 3D images, people felt more a sense of presence. Findings of this study have important practical implications how running time is important to 3DTV viewers. Since the nature of this study is exploratory, more research about segmented running time and genre, etc. of 3D stereoscopic videos will be needed.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.197-203
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• 2015

Particulate matter (PM) has emitted in many regions of the world and is causing many health-related problems. Thus reasonable politics and solutions are needed to reduce PM in Seoul. Further it is required to clearly explain the major portions of chemical components contained in $PM_{10}$ to figure out the characteristics of $PM_{10}$, and to develop effective reduction measures in order to decrease the adverse effects of $PM_{10}$. $PM_{10}$ samples were collected in Seoul and analyzed their ions to examine the physical and chemical characteristics of ionic species. Since hydrogen ion ($H^+$) and carbonate ion (${CO_3}^{2-}$)) cannot be analyzed by Ion chromatography (IC), concentrations of $H^+$ and ${CO_3}^{2-}$ were initially estimated by pH and equivalent differences between anions and cations in this study. Starting from the study findings, good combination results for compositional patterns between anions and cations were obtained by applying a mathematical modelling technique that was based on the mass balance principle. The ions in $PM_{10}$ were combined with $H^+$, ${CO_3}^{2-}$, and supplement for $NO_3{^-}$, $Cl^-$ formed such compounds $NH_4Cl$, $NH_4NO_3$, $CaSO_4$, $(NH_4)_2SO_4$, $NaNO_3$, NaCl, $Na_2CO_3$, and $(NH_4)_2CO_3$ in the study area.