• Journal of the Korean Geotechnical Society
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• v.24 no.3
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• pp.13-23
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• 2008

In a nonlinear site response analysis which is performed in time domain, small strain damping is modeled as viscous damping through use of various forms of Rayleigh damping formulations. Small strain damping of soil is known to be independent of the loading frequency, but the viscous damping is greatly influenced by the loading frequency. The type of Rayleigh damping formulation has a pronounced influence on the dependence. This paper performs a series of nonlinear analyses to evaluate the degree of influence of the viscous damping formulation on Korean soil profiles. Analyses highlight the strong influence of the viscous damping formulation for soil profiles exceeding 30 m in thickness, commonly used in simplified Rayleigh damping formulation overestimating energy dissipation at high frequencies due to artificially introduced damping. When using the full Rayleigh damping formulation and carefully selecting the optimum modes, the artificial damping is greatly reduced. Results are further compared to equivalent linear analyses. The equivalent linear analyses can overestimate the peak ground acceleration even for shallow profiles less than 20 m in thickness.

• Industry Promotion Research
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• v.8 no.3
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• pp.9-17
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• 2023

The purpose of this study is to look for the trends and rates of change of major passenger modes such as railway, subway, domestic shipping, domestic airline, international shipping and international airline. The data used were selected from the KOSIS, "Domestic Statistics, Statistics by Subject, Transportation and Logistics". The analysis period was 22 years from 1999 to 2020, and the annual rate of change from the previous year was calculated. In descriptive statistics, international shipping and international airlines showed relatively high volatility, whereas railway and subway showed low volatility. In the rise rate analysis, international air and international shipping dropped significantly from 539% and 368% in 2019 to 85% and 20% in 2020 due to Corona. International airline and international shipping fell significantly in 2020, but we expect them to rise again as the shock of Corona disappears in the future. Therefore, it seems that we need a project to prepare for this. International air and international shipping are expected to continue their upward trend as international trade picks up again and international travel regains its momentum.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.3
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• pp.223-228
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• 2023

Sustainable energy supplies without the recharging and replacement of the charge storage device have become increasingly important. Among various energy harvesters, the triboelectric nanogenerator (TENG) has attracted considerable attention due to its high instantaneous output power, broad selection of available materials, eco-friendly and inexpensive fabrication process, and various working modes customized for target applications. In this study, the amount of voltage and current generated was measured by applying the PSD profile random vibration test of the electronic vibration tester and ISTA 3A according to the time of Anodized Aluminum Oxide (AAO) pore widening of the manufactured TENG device Teflon and AAO. The discharge and charging tests of the integrated module during the random simulated transport environment and the recognition distance of RFID were measured while agricultural products (onion) were loaded into the returnable folding plastic box. As a result, it was found that AAO alumina etching processing time to maximize TENG performance was optimal at 31 min in terms of voltage and current generation, and the integrated module applied with the TENG module showed a charging effect even during the continuous use of RFID, so the voltage was kept constant without discharge. In addition, the RFID recognition distance of the integrated module was measured as a maximum of 1.4 m. Therefore, it was found that the surface condition of AAO, a TENG element, has a great influence on the power generation of the integrated module, and due to the characteristics of TENG, the power generation increases as the surface dries, so it is judged that the power generation can be increased if the surface drying treatment (ozone treatment, etc.) of AAO is applied in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.264-283
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• 2023

Unlike conventional vehicle traffic accidents, autonomous vehicles traffic accidents can be caused by various factors, including technical problems, the environment, and driver interaction. With the future advances in autonomous driving technology, new issues are expected to emerge in addition to the existing accident causes, and various scenario-based approaches are needed to respond to them. This study developed autonomous vehicle traffic accident scenarios by collecting autonomous driving accident reports, CA DMV collision reports, autonomous driving mode disengagement reports, and autonomous driving actual accident videos. The scenarios were derived based on the functional safety system failure modes of ISO 26262 and attempted to reflect the various issues of autonomous driving functions. The autonomous vehicle scenarios derived through this study are expected to play an essential role in preventing and preparing for various autonomous vehicle traffic accidents in the future and improving the safety of autonomous driving technology.

• Journal of the Korean Geographical Society
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• v.44 no.2
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• pp.176-186
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• 2009

Transportation policy to facilitate the public mode use is of the foremost importance to the local governments of Metropolitan Seoul, regarding the economic and environmental consequences of the increasing use of car. Understanding the travel behaviour is essential to the establishment of proper policy to guide more people to the use of public modes instead of private. The paper reports a result of sequential analysis of individual travel behaviour in Metropolitan Seoul, using a multi-dimensional motif search technique applied to Smart Card data that integrates individuals' different public mode uses. Groups of travel patterns with similar sequential information identified distinctive travel behaviour between Seoul north and south and between metro and bus uses. Travel patterns are more bounded within north Seoul and south Seoul respectively than crossing Han River between north and south. Within north and south, travel patterns visiting northern CBD and southern CBD, respectively, as well as their local neighbour in north and south, often use metro and metro-local bus combination, while travel patterns visiting only the north and south locals without CBDs more use only the local bus line and even only the areal bus line.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.37-46
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• 2014

Industrialization and urbanization have led automobiles to transform into more than just modes of transportation; they have become daily necessities as well as extensions of living spaces where a variety of activities can be done and automotive applications of the latest information technology are accelerated. Though material abundance has increased in the modern society, the conflicts and the stress emerging from a social structure focused on competition have increased as well. Such lifestyles generate a need for personal space and media content for healing the body and the mind. This research explores the automotive application of video content with the goal of refreshing the minds of the passengers. To this end, previous studies have investigated the emotional effect of videos, focusing on the responses of diverse groups of adults (age group of 20 to 60) who frequently used automobiles, which had video displays installed in them. The results showed that watching video contents on a full window inside a car influenced the creation of positive feelings7 and emotional satisfaction. The research attempts to study the methods of providing video contents and the effects of watching them that could aid the emotional well-being of passengers, and presents the possibility of emotional satisfaction created by a convergence of cars and multimedia contents in the future.

• Journal of the Economic Geographical Society of Korea
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• v.9 no.3
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• pp.379-395
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• 2006

The purpose of this study is to analyze the spatial characteristics of travel patterns and travel behaviors of transit users in the Metropolitan Seoul area. We apply the data mining techniques to explore the travel patterns of transit users from the T-money card database which has been produced over 10,000,000 transaction records per day. The database contains the information of locations and times of origin, transfer, and destination points for each transaction as well as the informations of transit modes taken via the transaction. We develop an data mining algorithm to explore traversal patterns from the enormous information. The algorithm determines the travel sequences of each passenger, and produce the volumes of support on each points (stops) of transportation networks in the Metropolitan Seoul area. In order to visualize the spatial patterns of travel demands for transit systems we apply GIS techniques, and attempt to investigate the spatial characteristics of travel patterns and travel demand. Subway stops located in the Gangnam area appear the highest peak for the travel origin and destination, while the CBD in the Gangbuk stands at the second position. Two or three sub-peaks appear at the densely populated residential areas developed as the high-rise apartment complex. Subway stations located along the Subway Line 2, especially from Guro to Samsung receive heavy travel demand (total support), while bus stops located at the CBD in the Gangbuk stands the highest travel demand by bus.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.163-172
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• 2003

As concrete structures are getting larger, higher, longer, and specialized, it is more required to develop steel fiber concrete and apply to the real world. In this research, it is aimed to have fatigue strength examined, varying the steel fiber content by 0%, 0.75%, 1.00%, 1.25%, by experimental study of Two-spans Beam with Steel Fibrous with repeated loads. The ultimate load and the initial load of flexural cracking were measured by static test. In addition, the load versus strain relation, load versus strain relation, load versus deflection relation, crack pattern and fracture mode by increasing weight was observed. On the other hand, the crack propagation and the modes of fracture according to cycle number and the relation of cycle loading to deflection relation and strain relation was observed by fatigue test. As the result of fatigue test, Two-spans Beam without Steel Fibrous was failed at 60~70% of the static ultimate strength and it could be concluded that fatigue strength to two million cycle was around 67.2% by S-N curve. On the other hand, that with Steel Fibrous was failed at 65~85% of the static ultimate strength and it could be concluded fatigue strength to two million cycle around 71.7%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.2
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• pp.119-126
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• 1983

The purposes of this study are to analyze/model the mode choice behavior of the regional traveler by express bus/express train and to offer useful source in deciding the public transportation policy. The data analyzed were trips of both modes from March, 1980 to November, 1981, between Seoul and other nineteen cities; the data were grouped as five groups according to the change of service variables. Service variables were travel time(unit: minute), cost(:won), average allocation time(:won), service hour(:hour), and dummy variables by mode. As model Logit Model with linear or log utility function were postulated. As the result of this study, some reseanable models were constructed at Model Type I(eq. 2. of this paper) based on the above data except the dummy. It was judged that the parameters calibrated by Group III and Group IV data in table 4, were optimal. Among the parameters, the parameter of travel cost was most reliable. There was a tendency preferring express bus to train in October and November. With the constructed model and Pivot-Point Method. the demand change of express train caused by the service variables' change could be forecasted over 99%.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.43-51
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• 2017

As per current seismic design codes, diagonally reinforced coupling beams are restricted to coupling beams having aspect ratio below 4. However, a grouped diagonally reinforcement detail makes distribution of steel bars in the beam much harder, furthermore it may result in poor construction quality. This paper describes the experimental results of concrete coupling beam reinforced with high-strength steel bars (SD500 & SD600 grades). In order to improve workability for fabricating coupling beams, a headed large diameter steel bar was used in this study. Two full-scale coupling beams were fabricated and tested with variables of reinforcement details and aspect ratio. To reflect real behavior characteristic of the beam coupling shear walls, a rigid steel frame system with linked joints was set on the reaction floor. As a test result, it was noted that cracking and yielding of reinforcement were initially progressed at the coupling beam-to-shear wall joint, and were progressed to the mid-span of the coupling beam, based on the steel strain and failure modes. It was found that the coupling beams have sufficient deformation capacity for drift ratio of shear wall corresponding to the design displacement in FEMA 450-1. In this study, the headed horizontal steel bar was also efficient for coupling beams to exhibit shear performance required by seismic design codes. For detailed design for coupling beam reinforced with high-strength steel, however, research about the effect of variable aspect ratios on the structural behavior of coupling beam is suggested.