• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1190-1196
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• 2016

In this paper, a cross-layer interworking scheme for different protocols is proposed to provide an efficient internet services in very small aperture terminal (VSAT) based satellite communication systems. In addition, we implement the proposed interworking model and prove the feasibility of the proposed system. VSAT based satellite communication systems commonly use digital video broadcasting (DVB)-S2 standard. Unfortunately, DVB-S2 has inefficient parts to support IP based internet services because it has originally been designed to support broadcasting services. Generic stream encapsulation (GSE) protocol, which is a layer 2 protocol, has been proposed to mitigate this inefficiency. We propose a cross-layer interworking scheme to cooperate efficiently between IP and GSE protocols and between GSE protocol and DVB-S2, respectively. In addtion, we implement the proposed interworking schemes via computer softwares and prove the feasibility using NI-USRP and commercial DVB receiver.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.133-136
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• 2019

Recently, many industrial devices are facing protocol compatibility problems with external monitoring and control systems. This paper designed an industrial communication gateway that can support the transformation of industrial communication protocol using multi-layered communication module. Industrial communication gateways have a structure that connects individual communication modules using rs485 serial communication to multiple layers. Each communication module consisted of analog data card, a digital data card LAN, and a CAN-enabled card. The main board processor used Atmega micro-processor, and the rs485 serial slot was placed to have a multi-layer communication module structure. These additive layer type communication modules support analog and digital I/O functions and LAN and CAN for wide use in industrial communication control and monitoring.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.5
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• pp.997-1006
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• 2019

To overcome the difficulties and inefficiencies of the existing power analysis attack, we try to extract the secret key embedded in a cryptographic device using attack model based on MLP(Multi-Layer Perceptron) method. The target of our proposed power analysis attack is the AES-128 encryption module implemented on an 8-bit processor XMEGA128. We use the divide-and-conquer method in bytes to recover the whole 16 bytes secret key. As a result, the MLP-based power analysis attack can extract the secret key with the accuracy of 89.51%. Additionally, this MLP model has the 94.51% accuracy when the pre-processing method on power traces is applied. Compared to the machine leaning-based model SVM(Support Vector Machine), we show that the MLP can be a outstanding method in power analysis attacks due to excellent ability for feature extraction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1673-1678
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• 2019

There are various networks and communication methods are used in industrial communication. Enterprises need to convert communications between industrial devices and networks for production line expansion, factory upgrades, network segmentation, and SI. This requires designers manufactured by many manufacturers to provide communication equipment for data or protocol conversion in order to connect and transmit various other mechanical devices to the network. This paper designed industrial communication gateway that can support the transformation of industrial communication protocol using multi-layered communication module. Industrial communication gateways have a structure that connects individual communication modules using RS485 communication to multiple layers. Each communication module consisted of analog and digital data card, LAN, and CAN-enabled card. The main board processor used Atmega micro-processor, and the RS485 slot was placed to have a multi-layer communication module structure. These additive layer type communication modules support analog and digital I/O functions and LAN and CAN for wide use in industrial communication control and monitoring.

• Journal of the Korean Geosynthetics Society
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• v.21 no.3
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• pp.49-59
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• 2022

This study was conducted to find out the rational and appropriate design of drilled shaft. In other words, in order to find out the variation of ultimate bearing capacity according to the change in the support layer of drilled shaft, back analysis was performed using the bi-directional pile load test performed on drilled shaft. Based on the back-analyzed data, numerical analysis of the pile head load was performed, and the ultimate bearing capacity in the target ground was evaluated using the Davisson method. As a result of numerical analysis of one case where the end of the pile was seated on the top of the weathered rock layer, and three cases where the end of the pile was embedded at different locations in the weathered soil, it was found that sufficient ultimate bearing capacity was secured in all cases. In other words, the case where the end of the pile is seated on the top of the weathered rock layer, not embedded the weathered rock, and the drilled shaft embedded into the weathered soil also have sufficient bearing capacity, so it can be used as a support layer for drilled shaft.

• Steel and Composite Structures
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• v.47 no.1
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• pp.91-102
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• 2023

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train sub-model was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h - 350 km/h train running speed, the limit values of grade I, II, and III of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

• Membrane Journal
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• v.14 no.1
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• pp.57-65
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• 2004

The effect of porous support layer resistance and PDMS (polydimethylsiloxane) coating thickness on ethylene/nitrogen separation of composite membranes was studied with the model of Pinnau and Wijmans〔1〕. To control the support resistance (or permeance), PES porous membranes were prepared by phase inversion process with various PES/NMP dope concentrations. The thickness of selective PDMS top layer was controlled by using a spin coater. Its cross-section and coating thickness were observed by scanning electron microscope (SEM). Pure gas permeation test was done with ethylene and nitrogen, respectively. The experimental result for olefin/nitrogen separation process matched well with theoretical result from the model used. The result shows that optimization between PDMS coating thickness and support resistance is important to get PDMS composite membranes with best performance.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1936-1939
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• 2004

This paper proposes streaming layer for personal robot's middleware. Under assumption that robot has open architecture, i.e. consists of modules created by different vendors and intercommunication between these modules is necessary, we have to consider that there are many different network interfaces. To make communication between modules possible it is necessary to develop new type of middleware. Such middleware has to support different platforms, i.e. OS, network interface, hardware, etc. In addition, it is necessary to implement effective interface between network and application in order to manage inter application communications and use network resources more effectively. Streaming layer is such interface that implements necessary functionality together with simplicity and portability. Streaming layer provides high level of abstraction and makes communication between distributed applications transparent as if are located in same module. With possibility of extension by user defined application interfaces it is suitable for distributed environments, i.e. module based architecture including small-embedded systems like as DSP board. To verify the proposed streaming layer structure it is implemented using C and tested.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.52-55
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• 2004

VMS (virtual manufacturing system) may be defined as a transparent interface/control mechanism to support human decision-making via simulation and monitoring of real operating situation through modeling of all activities in RMS (real manufacturing system). The three main layers in VMS are business process layer, manufacturing execution layer, and facility operation layer, and each layer is represented by a specific software system having its own input modeler module. The current version of these input modelers has been implemented based on its own 'local' framework, and as a result, there are no information sharing mechanism, nor a common user view among them. Proposed in this paper is a unified modeler framework covering the three VMS layers, in which the concept of PPR (product-process-resource) model is employed as a common semantics framework and a 2D graphic network model is used as a syntax framework. For this purpose, abstract class PPRObject and GraphicObject are defined and then a subclass is inherited from the abstract class for each application layer. This feature would make it easier to develop and maintain the individual software systems. For information sharing, XML is used as a common data format.

• Journal of Environmental Impact Assessment
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• v.12 no.4
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• pp.271-279
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• 2003

Temperature and humidity forecasting have been performed using artificial neural networks model(ANN). We composed ANN with multi-layer perceptron which is 2 input layers, 2 hidden layers and 1 output layer. Back propagation algorithm was used to train the ANN. 6 nodes and 12 nodes in the middle layers were appropriate to the temperature model for training. And 9 nodes and 6 nodes were also appropriate to the humidity model respectively. 90% of the all data was used learning set, and the extra 10% was used to model verification. In the case of temperature, average temperature before 15 minute and humidity at present constituted input layer, and temperature at present constituted out-layer and humidity model was vice versa. The sensitivity analysis revealed that previous value data contributed to forecasting target value than the other variable. Temperature was pseudo-linearly related to the previous 15 minute average value. We confirmed that ANN with multi-layer perceptron could support pollutant dispersion model by computing meterological data at real time.