• Proceeding of KASS Symposium
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• 2008.05a
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• pp.15-18
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• 2008

A Spatial structure, having a curvature with a curved surface, is an extremely efficient mechanical creation considering the external load. It is resisted the out-of-plane direction load by in-plane forces using the structure's curvature. Spatial Structures include many types of structures, such as: space frames or grids; cable-and-strut and tensegrity; air-supported or air-inflated; self-erecting and deployable; cable net; tension membrane; lightweight geodesic domes; folded plates; and thin shells. Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. It is very important that effects by wind load than seismic and dead load. And, wind load is different by surrounding and shape of building In this study, we analyze the results of design wind load and wind tunnel tests about the 2 stadiums which are constructed on sensitive sites by effect of wind loads.

• Geomechanics and Engineering
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• v.27 no.6
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• pp.537-550
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• 2021

There are various technical problems need to be solved in the construction process of pre-setting an isolation wall into a double lane in the outburst prone mine. This study presents a methodology that pre-setting an isolation wall into a double lane without a coal pillar. This requires the excavation of two small section roadways to dig a wide section roadway, followed by construction of the separation wall. During this process the connecting lane is reserved. In order to ensure the stability of the separation wall, the required bearing capacity of the isolation wall is 4.66 MN/m and the deformation of the isolation wall is approximately 25 cm. To reduce the difficulty of implementing support the roadway is driven by 5 m/d. After the construction of the separation wall, the left side coal wall is brushed 1.5 m to make the width of the gas roadway reach 2.5 m and the roadway support utilizes anchor rod, ladder beam, anchor cable beam and net configuration. During construction, the concrete pump and removable self-propelled hydraulic wall mold are used to pump and pour the concrete of the isolation wall. In the process of mining, the stress distribution of coal body and isolation wall is detected and measured on site. The results demonstrate that the deformation of the surrounding rock of roadway and separation of roof in the roadway is small. The stress of the bolt and anchor cable is within equipment tolerance validating their selection. The roadway is well supported and the intended goal is achieved. The methodology can be used for reference for similar mine gas control.

• Journal of KIISE:Information Networking
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• v.37 no.3
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• pp.187-197
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• 2010

The fusion stream of recent broadcasting and communication make multimedia content served in the area of broadcasting into IPTV service which transmits it through high-speed internet, cable TV net and satellite net in realtime. However, as the digital broadcasting service is extended to various media, the security of IPTV service content provided to users by service provider is not fully supported by CAS(Conditional Access System) provided by existing broadcasting system. This paper proposes interactive certification protocol which can efficiently distinguish the receiving-qualification of user between Set-Top Box and Smart Card which are parts of configurations for IPTV system. The proposed protocol uses hash function to make Set-Top Box transmit receiving-qualification about the channel fee which user pays more properly than existing protocol. Also, the proposed protocol uses session key generated between receiver and smart card through inter certification process and encrypts EMM not the service to be used by anyone illegally.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.68-75
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• 2013

Recently IPTV that transmits multimedia contents in real time through internet, cable TV net and satelite net gets the limelight. But IPTV service that gives service to users by various media has a problem of not supporting user certification fully. This paper suggests a certification model which prevents getting access permission of IPTV service by sending illegal certification information by adolescent through integrating mobile communication technique with RFID(Radio Frequency IDentification) technique which is a key technique of Ubiquitous environment. This model performs the process of adult certification by keeping synchronization with user's certificaiton information that is saved in data-base of certification server and contents server after getting the system of class categorization in contents server to overcome disadvantage of simple adult certification system that is popular in the existing internet. Also, it adapts double hash chain technique not to down load illegally contents without the permission of manager even if an adolescent gets manager's approval key.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.229-240
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• 2010

Most of all researchs and analyses in the field of television industry of Korea were related to Cable Television SO(System Operator), but few about PP(Program Provider) from the viewpoint of Industrial Theory in Korea. However, there wasn't a comprehensive research analysis in terms of the co-relationship of the market structure, market conduct and market performance of PP. This research analyzes co-relationship and dynamics of the market structure of PP, its market conduct and market performance in a comprehensive way in Cable TV industry. Especially this paper focuses on the analysis of 1)relationship and its influence between market structure and market conduct, 2) relationship and its influence between their market conducts and market performances and 3) relationship and its influence between market structure and market performance among 40 commercial PPs in terms of the theory of Industrial Organization in Korea. This paper is delated and reported as follows in conclusion : 1)the type of horizontal integration has an effect on the price and scale in the relationship between the structure and its conduct. 2)the price has effect on the revenue and viewing rate between the conduct and performance. And high dependency of the Cable TV license fee has an effect on viewing rate and revenue per subscribers(ARPU) between the conduct and performance. 3)The horizontal integration between the structure and performance had a positive effect on viewing rate and its product differentiation has an effect on the revenue per subscribers. Net cost of the product had a negative effect on the rate of profit.

• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.1-7
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• 2004

In addition to wired communication technology, wireless communication technology has been driving communication revolution nowadays. Bluetooth technology carries out data/voice communication making pico-net and the various application services are supported by access network connected to public network. This paper presents educational software development of bluetooth protocol stack including HCI, L2CAP, RFCOMM, SDP and profiles including GAP, SPP, GEOP, FTP. This software which supports programming environment of these protocol monitoring and emulation is implemented basically step by step for education based on H connected to the bluetooth device through RS-232-C, UART or USB cable. Application program coded by Visual C is operated over the firmware loaded on the bluetooth device connected to the PC. Additionally ftp and chatting function are developed to enhance educational efficiency.

• Journal of Communications and Networks
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• v.18 no.6
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• pp.962-974
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• 2016

We are concerned with whether a vertically integrated broadband and content provider can unreasonably advantage itself over competing content providers, either by selling quality-of-service (QoS) to content providers at unreasonably high prices, or by refusing to provide access to QoS to competing content. We address this question by modeling the competition between one such vertically integrated provider and one over-the-top (OTT) content provider. The broadband provider decides whether to deploy QoS, and if so it also determines the QoS price if sold to either the OTT content provider or directly to users. We analytically determine when the broadband provider will sell QoS and when the OTT content provider or users will purchase QoS. We characterize the optimal QoS and video service prices. The Internet service provider (ISP)'s market share increases with the difference in the value of the two video services and decreases with the difference in the corresponding costs. Numerical results illustrate the effect of QoS price on content price, the variation of prices and profit with QoS price, and the variation of prices and market shares with the benefit of QoS. The ISP may sell QoS to users at a lower price than when QoS is sold to the OTT provider.

• Smart Structures and Systems
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• v.29 no.1
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• pp.63-75
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• 2022

The raw data collected by structural health monitoring (SHM) systems may suffer multiple patterns of anomalies, which pose a significant barrier for an automatic and accurate structural condition assessment. Therefore, the detection and classification of these anomalies is an essential pre-processing step for SHM systems. However, the heterogeneous data patterns, scarce anomalous samples and severe class imbalance make data anomaly detection difficult. In this regard, this study proposes a convolutional neural network-based data anomaly detection method. The time and frequency domains data are transferred as images and used as the input of the neural network for training. ResNet18 is adopted as the feature extractor to avoid training with massive labelled data. In addition, the focal loss function is adopted to soften the class imbalance-induced classification bias. The effectiveness of the proposed method is validated using acceleration data collected in a long-span cable-stayed bridge. The proposed approach detects and classifies data anomalies with high accuracy.

• Journal of Information Technology Applications and Management
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• v.26 no.6
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• pp.103-117
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• 2019

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.2
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• pp.47-59
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• 2017

This study aims to assess offshore wind energy resources around Jeju Island using the InVEST Offshore Wind model. First the wind power density around the coast of Jeju was calculated using reanalysis data from the Korean Local Analysis and Prediction System (KLAPS). Next, the net present value (NPV) for the 168MW offshore wind farm scenario was evaluated taking into consideration factors like costs (turbine development, submarine cable installation, maintenance), turbine operation efficiency, and a 20year operation period. It was determined that there are high wind resources along both the western and eastern coasts of Jeju Island, with high wind power densities of $400W/m^2$ calculated. To visually evaluate the NPV around Jeju Island, a classification of five grades was employed, and results showed that the western sea area has a high NPV, with wind power resources over $400W/m^2$. The InVEST Offshore Wind model can quickly provide optimal spatial information for various wind farm scenarios. The InVEST model can be used in combination with results of marine ecosystem service evaluation to design an efficient marine spatial plan around Jeju Island.