• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.346-347
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• 2020

This paper presents the two combination methods for leakage current reduction in photovoltaic system PCS. The leakage current in the photovoltaic system generated from the parasitic capacitance existing between the photovoltaic system and ground relevance to common mode voltage caused by PWM switching. Firstly, Leakage current reduced by a PWM method using two carriers with 180-degree phase different. Secondly, the leakage current is more reduced by connecting LCL filter to the mid-point of DC link. This combining method is revealed in PSIM simulation with 1 uF parasitic capacitance.

• Steel and Composite Structures
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• v.51 no.3
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• pp.305-323
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• 2024

Previous experimental studies have effectively demonstrated the remarkable efficiency of the stiffened channel link in connecting circular columns and I-shaped beams. This research aims to present design criteria and assess the seismic properties of this specific connection type through numerical modeling. Various parameters, including stiffener type and geometric properties of the stiffened channel element, were duly taken into account. The findings from over 136 nonlinear finite element analyses (FEAs) reveal that the recommended detailing scheme reliably satisfies all the regulations specified for rigid beam-to-column connections in special moment frames.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.117-130
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• 2005

In both deteministic user Optimal Traffic Assignment Model (UOTAM) and stochastic UOTAM, travel time, which is a major ccriterion for traffic loading over transportation network, is defined by the sum of link travel time and turn delay at intersections. In this assignment method, drivers actual route perception processes and choice behaviors, which can become main explanatory factors, are not sufficiently considered: therefore may result in biased traffic loading. Even though there have been some efforts in Stochastic UOTAM for reflecting drivers' route perception cost by assuming cumulative distribution function of link travel time, it has not been fundamental fruitions, but some trials based on the unreasonable assumptions of Probit model of truncated travel time distribution function and Logit model of independency of inter-link congestion. The critical reason why deterministic UOTAM have not been able to reflect route perception cost is that the route perception cost has each different value according to each origin, destination, and path connection the origin and destination. Therefore in order to find the optimum route between OD pair, route enumeration problem that all routes connecting an OD pair must be compared is encountered, and it is the critical reason causing computational failure because uncountable number of path may be enumerated as the scale of transportation network become bigger. The purpose of this study is to propose a method to enable UOTAM to reflect route perception cost without route enumeration between an O-D pair. For this purpose, this study defines a link as a least definition of path. Thus since each link can be treated as a path, in two links searching process of the link label based optimum path algorithm, the route enumeration between OD pair can be reduced the scale of finding optimum path to all links. The computational burden of this method is no more than link label based optimum path algorithm. Each different perception cost is embedded as a quantitative value generated by comparing the sub-path from the origin to the searching link and the searched link.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.71-85
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• 2017

The $4^{th}$ industrial revolution is a super connection society. It connects all things between things and things, PC and mobile phone, human and human and human and things. In Jeju island, 'Batdam' and 'Sandam' are conneted like 'black dragon ten thousand Li', and stone walls are connected to each other as the stone network, which is called as the 'Goendam' (and conventionally is told as the 'Goendang') and is related to the Family network. Also, IoT(Internet of Things) makes the connection between the stone network and people. The Jeju's fourth industrial revolution is a its testbed. 'Goendang' connection in 4G industrial revolution is shown to be important Node and Link in socially and mathematically. In this paper, we review the historical background of the Goendang and find combinations of stones on the various types of stone field using the algebraic geometry.

• The Journal of Korean Association of Computer Education
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• v.14 no.2
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• pp.47-59
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• 2011

Linked Data is about using the web to link related data that wasn't linked previously. To publish linked data, people should be able to represent, share, and link pieces of data, information, and knowledge by using URIs and RDF. However, building linked data is not easy for the common users who do not know the knowledge or skill about using URIs and RDF. In this paper, we present a system that the common users can create linked data by connecting data originated from different RDFs. They build linked data by adding new links to connect between RDF data saved in their computers or searched from Swoogle. We can apply the proposed system to creating educational contents. For example, teachers can develop various learning contents by building linked data that connects different data suited to the learning level of their students.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.361-367
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• 2014

This paper is related to a new solar power conditioner for a built-in step-up chopper function. In the first step-up chopper proposed solar PV power conditioner for mutually connected in series with the input voltage of the bypass diodes are respectively connected to the positive terminal should install the mutual boosting chopper diode connected in series with the boost chopper switching element between the two power supply and at the same time the first and the second was connected to a second diode and a resonance inductor and a snubber capacitor in series with each other. And the common connection point between the bypass diode and the step-up chopper and the step-up chopper diode common connection point of the switching elements of the input voltage was set to the boost inductor for storing energy. In addition, between the step-up chopper and the step-up chopper diode and a switching element of a joint connection point of the first auxiliary diode and the second common connection point of the auxiliary diode was provided, the resonance capacitor. Between the step-up chopper and the step-up chopper diode and a switching element of a joint connection point and the common connection point of the resonance inductor snubber capacitor and connecting the third secondary diode, between two power supply lines is characterized by configuring the DC link capacitor bus lines in parallel. Therefore, it is possible to suppress the switching loss through, DC link bus lines, as well as there could seek miniaturization and weight reduction of the power conditioner itself by using a common capacitor of the non-polar non-polar electrolytic capacitor having a capacitor, the service life of the circuit can be extended and it is possible to greatly reduce the loss can be greatly improve the reliability of the product and the operation of the product itself.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.528-531
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• 2004

This paper presents the design and implementation of a QoS based IrDA in mobile phones. The IrDA standards have arised from the need to connect various mobile devices together. But currently, we have a difficult to connecting various mobile devices together. The difficult thing is to adjust the minimum turn around time. The minimum turn around time in IrDA deals with the time needed for a receiver circuit to recover following saturation by transmissions from the same device (turn around latency). This parameter corresponds to the required time delay between the last byte of the last frames sent by a station and the point at which it is ready the first byte of a frame from another station. This parameter comes into play when the link is turned around and is negotiated independency for each station. We solve this matter by using the Dynamic Adjustment Algorithm (DAA). The dynamic adjustment algorithm adjusts the minimum turn around time according to the numbers of devices. We apply our direct adjustment algorithm to our QoS based IrDA in mobile phones and show the improved performance of connection with various mobile phones together.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.11
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• pp.37-44
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• 2008

Recently, there have been intensive researches on the wireless Internet access through WiFi WLAN using WiBro network as backhaul link in the Internet service providing business area. However, in the wireless Internet access method, we need to solve the compatibility problem for different user authentications between licensed WiBro network and unlicensed WiFi network for billing and user management. In this paper, we propose an authentication method for WiFi users by BWAN operators through WiNNERs which is RS connecting the two networks, and discuss the effectiveness of the method.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.164-171
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• 2006

In this paper, the fault tolerant system for BLDC motor has been proposed to maintain control performance under an open switch fault of inverter. The fault identification is proposed to two methods, which are using the difference between reference and actual current, and adding voltage sensors across lower legs of inverter. The reconfiguration scheme is achieved by the four-switch topology connecting a faulty leg to the middle point of DC-link using bidirectional switches. The proposed fault tolerant system quickly recovers control performance by short fault detecting time and reconfiguration of system topology. Therefore, continuous free operation of the BLDC motor drive system after faults is available. The superior performance of the proposed fault tolerant system is proved by simulation.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1011-1017
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• 2009

In pursuit of the Trans-Korea Railway (TKR) project connecting the Korean peninsular by a rail link, it is critical that the two railway systems in ROK and DPRK are comparable in criteria and standards. Yet, there is substantial divergence of the construction criteria between the two sides, which hinders from conducting the TKR project as well as the railway modernization of DPRK. In this regard, study and comparison of the criteria are a prerequisite for mitigating the hinderance. This study investigated the laws and regulations relating to the railway technologies and construction and in particular conducted a comparative analysis of both railway systems with a focus on railway facilities such as track, structures, electric power and signaling. The results of this study will provide a useful information for the improvement of existing lines and the construction of new lines in DPRK.