• Earthquakes and Structures
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• v.16 no.3
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• pp.349-358
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• 2019

Long span cable-stayed bridges are extremely vulnerable to dynamic excitations such as which caused by traffic load, wind and earthquake. Studies on cable-stayed bridge vibration control have been keenly interested by researchers and engineers in design new bridges and assessing in-service bridges. In this paper, a novel Hybrid-Tuned Mass Damper (H-TMD) is proposed and a hybrid control model named Mixed Logic Dynamic (MLD) is employed to build the bridge-H-TMD system to mitigate the vibrations. Firstly, the fundamental theory and modeling process of MLD model is introduced. After that, a new state switching design of the H-TMD and state space equations for different states are proposed to control the bridge vibrations. As the state switching designation presented, the H-TMDs can applied active force to bridge only if the structural responses are beyond the limited thresholds, otherwise, the vibrations can be reduced by passive components of dampers without active control forces provided. A new MLD model including both passive and active control states is built based on the MLD model theory and the state switching design of H-TMD. Then, the case study is presented to demonstrate the proposed methodology. In the case study, the control scheme with H-TMDs is applied for a long span cable-stayed bridge, and the MLD model is established and simulated with earthquake excitation. The simulation results reveal that the suggested method has a well damping effect and the established system can be switched between different control states as design excellently. Finally, the energy consumptions of H-TMD schemes are compared with that of Active Tuned Mass Damper (ATMD) schemes under variable seismic wave excitations. The compared results show that the proposed H-TMD can save energy than ATMD.

• The Korean Journal of Air & Space Law and Policy
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• v.17
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• pp.111-132
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• 2003

The air transport industry is the most important as means of human exchange between the countries. Because the spread effect and the durability by aviation cooperation between the countries are much higher than any other industry, a research about air transport industry is very important to allied industry field as well as national policy about International cooperation and integration. Specially, according to the economic interchange with North Korea becomes active, the role of air transport as related traffic network with North Korea becomes more important. The number of flights is increasing sharply after South-North summit meeting, and two sides established and are using temporary direct route between South-North Korea. When we consider that the number of flights utilizing temporary direct route is increasing every year, It is not desirable to use temporary routes continuously because the current agreement between South and North cant be reliable far the case of unexpected circumstance. In addition, the current agreement is not based on the international standards. The paper is to study the condition to promote the coordination of civil aviation in the whole Korean peninsula. As known, the aviation system in North Korea is mainly operated by military unit. The study will review the current status of air transport system of South and North and the effective way of cooperation of civil aviation between both sides. The cooperation between governments as well as between airlines is studied. The establishment of Air Traffic Service Agreement is going to be handled heavily because the stable air traffic service is the most required base for the operation of air transport. The authors also try to find a way to support the development of infrastructure of aviation industry in North Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.321-330
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• 2020

The purpose of this study is to present the appropriate standby space for the mechanical parking lot considered parking queue. This analysis is based on the field-study by results of the influential factors on the parking queue of mechanical parking lots in the commercial area of Gwang-ju metropolitan city. In this study, the parking queue was analized through the simple modeling using Vissim based on average service rate and average arrival rate from the result of field-study. As a result of applying the field survey products to the theoretical queue model, no significant result was obtained when the traffic intensity exceeded 1. Therefore, parking queue was analyzed through simple modeling using Vissim, and the model for calculating the proper parking queue size of the mechanical parking lot by size was derived. The model for estimating of an appropriate mechanical parking standby space considering parking queue presented in this study is expected to be a criterion for considering the appropriate parking space of a new building, and also it can be used to minimized the traffic impact due to the parking queue by the lack of standby space.

• Spatial Information Research
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• v.23 no.2
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• pp.49-57
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• 2015

Recently, Through the linkage and opening, the fusion of the spatial information, it is necessary for productive ecosystem to provide a variety of information and to increase the civil use. Depending on the economic growth, demand for quality of life and well-being has been on the increase. Spatial information service contents for the public convenience has emerged to solve the problem such as health, safety, welfare and discomfort of daily life This study aims to implement search services for a tailored residence space through the three-dimensional data modeling on cadastral information. To achieve this goal, we established the requirements for deriving a registered object by investigating recent trend with respect to existing cadastral data model and defined property and relationship. Focusing on Songpa-gu, Jamsil station in Seoul, we implemented search services for a tailored residence space for three-dimensional right analysis in conjunction with residential and commercial complex building. As a result, we derived a way to supply 3D cadastre information through open platforms (VWorld) and to represent efficiently, which is able to improve the quality of spatial information service contents for the public convenience as well as to widen utilization of information.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.101-108
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• 2024

The total number of railroad stations managed in Korea is 322 (including general and wide-area railways), and a considerable number of stations are aging. In terms of the size of the existing railway station and the number of entrances, it has not been possible to secure adequate service capacity, and the demand for station improvement is increasing due to changes in surrounding conditions such as urban development. In the past, railroad stations were focused on the simple function of a connection passage in terms of maintenance or management, but in recent years, railroad stations are also changing to an atmosphere that they should be reborn as a user-centered comfortable, convenient, and safe service provision space. In this study, a case study related to the improvement of the old railway station was conducted to derive an improvement plan that meets the improvement standard of the old station, and the service level evaluation standard was developed. By introducing the concept of service level (LOS) in the development model, station congestion, station movement convenience, and station safety were selected as evaluation indicators. In addition, this development model applied an analytical stratification technique to divide various evaluation elements of each indicator into major and detailed elements and derive the relative importance of the elements by class. Priority for improvement was derived using the ratio of the number of E and F on the LOS for each facility. Based on this study, it is expected to be helpful in using it as an evaluation criterion for improving objective and equitable railway station.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1029-1044
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• 2017

The Discrete Element Method (DEM) is one of the useful numerical methods to analyze the behavior of the ground formation by computing the motion and interaction using particles. The DEM has not been applied in civil engineering but also a wide range of industrial fields, such as chemical engineering, pharmacy, material science, food engineering, etc. In this study, to review a performance of the spoke-type earth pressure balance (EPB) shield TBM (Tunnel Boring Machine), the commercial software based on the DEM technology was used. An analysis of the TBM during excavation was conducted according to two pre-defined excavation conditions with the different rotation speed of a cutterhead. During the analysis, the resistant torque at the face of the cutterhead, the compressive force at the cutterhead and shield surface, the muck discharge at the screw auger were measured and compared. Upon the two kinds of excavation conditions, the applicability of the DEM analysis was reviewed as a modelling method for the TBM.

• Journal of Korea Multimedia Society
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• v.24 no.8
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• pp.1138-1148
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• 2021

In this study, we developed a 'shared-use mobility'-mounted local particulate matter monitoring terminal technology to measure the actual particulate matter concentration around me. As a mobile terminal device in the form of an IoT sensor platform, it is designed to be separated into a control module and a sensor module to minimize interference between sensors and to consider the optimal observation position of each sensor. As a result of the field test, it was confirmed that particulate matter was locally different depending on time and space even within the same area. In addition, it was confirmed that the concentration of particulate matter in the relevant section differed by up to 100 times compared to the surrounding area due to specific sources of particulate matter such as unpaved roads. In addition, we positively reviewed the applicability of the service in the real-time metaverse environment using this result. Through technological advancement and application of multiple shared-use mobilities, we expect to be able to provide new services for practical smart city air environment monitoring, such as localized particulate matter information, air pollution event information, and identification of causes of particulate matter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.645-654
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• 2009

This study started with necessity of historical spatial planning skills in U-city planning. Though U-city technology and information are very important, U-city development should be considered on the base of various experience of spatial planning. This study explored spatial planning indexes change in the recent newtown plans. In particular, safety and security were intensively analyzed. In addition, many theories on safe urban space, ubiquitous technology, traditional defensible space, and CPTED (Crime Prevention through Environmental Design) are compared. The findings are as follows. First, each planning is not integrated and there is lack of network among each planning. Specifically, from the crime prevention perspective, there is only mechanical monitoring such as CCTV without architectural approach. Even though CCTV is social needs, it is necessary to adopt it with architectural environment in order to improve the synergy effect of spatial planning and non-spatial planning.

• The Korean Journal of Air & Space Law and Policy
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• v.12
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• pp.246-274
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• 2000

This paper discusses the qualification criteria for international hub airport and suggests the strategies for Inchon International Airport (IIA) to be the hub airport in the East Asia. Recently, many East and Southeast Asia countries have invested on large scale international airports like Chap Lak Kok airport, Pudong airport etc.. as Korea have done on IIA. IIA to be open in 2001 will face a serious competition with these airport. Being a hub airport requires geographic proximity. sufficient volume of local traffic. uncongested infrastructure, a good accessibility to surrounding industrial centers. high quality of service to the airline. In order to promote airlines to land at IIA. Korea Government need to establish Open Sky Policy to many countries and national flag carriers of Korea need to be involved in a global alliance. Developing vicinity of IIA as free trade zone will generated more local traffic which makes IIA as more attractive candidate for airlines. The Korea airspace is one of the most restricted area in the world becuase of the national security. which limits civil aircraft maneuvers. The airspace need to be re-structured to exploit the full capacity of IIA.

• Journal of Astronomy and Space Sciences
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• v.20 no.1
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• pp.1-10
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• 2003

A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position. p-KOD utilizes the precise GPS orbits and ground stations data from International GPS Service (IGS) so that the only unknown parameters to be solved are positions of the satellite at each epoch. Currently, the 3-D accuracy off-KOD applied to CHAMP (CHAllenging Min-isatellite Payload) shows better than 35 cm compared to the published rapid scientific orbit (RSO) solution from GFZ (GeoForschungsZentrum Potsdam). The data screening for cycle slips is a particularly challenging procedure for LEO, which moves very fast in the middle of the ionospheric layer. It was found that data screening using SNR (signal to noise ratio) generates best results based on the residual analysis using RSO. It is expected that much better accuracy are achievable with refined prescreening procedure and optimized geometry of the satellites and ground stations.