• Convergence Security Journal
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• v.23 no.5
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• pp.57-64
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• 2023

In this study, we analyzed how to steal the target model without training data. Input data is generated using the generative model, and a similar model is created by defining a loss function so that the predicted values of the target model and the similar model are close to each other. At this time, the target model has a process of learning so that the similar model is similar to it by gradient descent using the logit (logic) value of each class for the input data. The tensorflow machine learning library was used as an experimental environment, and CIFAR10 and SVHN were used as datasets. A similar model was created using the ResNet model as a target model. As a result of the experiment, it was found that the model stealing method generated a similar model with an accuracy of 86.18% for CIFAR10 and 96.02% for SVHN, producing similar predicted values to the target model. In addition, considerations on the model stealing method, military use, and limitations were also analyzed.

• Convergence Security Journal
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• v.24 no.2
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• pp.55-61
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• 2024

With the development of IoT technology, wearable services have also developed rapidly. Wearable devices required for this service are used as sensors and controllers in the form of smart bands. Wearable devices implement very concise SWlogic for possible long-term use and use wireless communication protocols to improve convenience. However, because this wearable device aims to be lightweight, it is more vulnerable to security than terminals used for other information services. Many smart healthcare or smart medical services are passive or do not apply security technology. By exploiting this security environment, attackers can obtain or modify important information through access to wearable devices. In this study, we analyzed the technical operating environment of wearable services and identified authentication information reuse attacks, BIAS attacks, battery drain attacks and firmware attacks on wearable devices. And we analyzed the mechanism of each security threat and confirmed the attack effect. In this study, we presented a response plan to respond to the identified security threats. When developing wearable services, it is expected that safer services can be built if the response plan proposed in this study is considered.

• Smart Media Journal
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• v.12 no.11
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• pp.67-76
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• 2023

We propose a visualization method to respond to civil complaints through an analysis of the impact of blasting. In order to analyze the impact of blasting on tunnel excavation, we propose a simulation visualization method considering the mutual influence of the construction infrastructure by linking measurement data and 3D BIM model. First, the level of BIM modeling required for simulation was defined. In addition, vibration measurement data were collected for the GTX-A construction site, terrain and structure BIM were created, and a method for visualizing measurement data using blast vibration estimation was developed. Next, a spherical blasting influence source library was developed for visualization of the blasting influence source, and a specification table that could be linked with Revit Dynamo automation logic was constructed. Using this result, a method for easily visualizing the impact analysis of blasting vibration in 3D was proposed.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.63-73
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• 2015

This work proposes a 2-channel time-interleaved (T-I) 10b 120MS/s pipeline SAR ADC minimizing offset mismatch between channels without any calibration scheme. The proposed ADC employs a 2-channel SAR and T-I topology based on a 2-step pipeline ADC with 4b and 7b in the first and second stage for high conversion rate and low power consumption. Analog circuits such as comparator and residue amplifier are shared between channels to minimize power consumption, chip area, and offset mismatch which limits the ADC linearity in the conventional T-I architecture, without any calibration scheme. The TSPC D flip-flop with a short propagation delay and a small number of transistors is used in the SAR logic instead of the conventional static D flip-flop to achieve high-speed SAR operation as well as low power consumption and chip area. Three separate reference voltage drivers for 4b SAR, 7b SAR circuits and a single residue amplifier prevent undesirable disturbance among the reference voltages due to each different switching operation and minimize gain mismatch between channels. High-frequency clocks with a controllable duty cycle are generated on chip to eliminate the need of external complicated high-frequency clocks for SAR operation. The prototype ADC in a 45nm CMOS technology demonstrates a measured DNL and INL within 0.69LSB and 0.77LSB, with a maximum SNDR and SFDR of 50.9dB and 59.7dB at 120MS/s, respectively. The proposed ADC occupies an active die area of 0.36mm2 and consumes 8.8mW at a 1.1V supply voltage.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.251-258
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• 2012

Recently, NAND Flash memory structure is evolving from SDR (Single Data Rate) to high speed DDR(Double Data Rate) to fulfill the high performance requirement of SSD and SSS. Accordingly, the proper ways of transferring data that latches valid data stably and minimizing data skew between pins by using PHY(Physical layer) circuit techniques have became new issues. Also, rapid growth of speed in NAND flash increases the operating frequency and power consumption of NAND flash controller. Internal voltage variation margin of NAND flash controller will be narrowed through the smaller geometry and lower internal operating voltage below 1.5V. Therefore, the increase of power budge deviation limits the normal operation range of internal circuit. Affection of OCV(On Chip Variation) deteriorates the voltage variation problem and thus causes internal logic errors. In this case, it is too hard to debug, because it is not functional faults. In this paper, we propose new architecture that maintains the valid timing window in cost effective way under sudden power fluctuation cases. Simulation results show that the proposed technique minimizes the data skew by 379% with reduced area by 20% compared to using PHY circuits.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.6
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• pp.18-26
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• 2011

Debates concerning the competitive edge of leading 3DTV technology of the shutter glasses (SG) 3D and the film-type patterned retarder (FPR) are flaring up. Although SG technology enables Full-HD 3D vision, it requires complex systems including the sync transmitter (emitter), the sync processor chip, and the LCD lens in the active shutter glasses. In addition, the transferred sync-signal is easily affected by the external noise and a 3DTV viewer may feel flicker-effect caused by cross-talk of the left and right image. The operating current of the sync processor in the 3DTV active shutter glasses is gradually increasing to compensate the sync reconstruction error. The proposed chip is a low-power hardware sync processor based discrete-event SoC(system on a chip) designed specifically for the 3DTV active shutter glasses. This processor implements the newly designed power-saving techniques targeted for low-power operation in a noisy environment between 3DTV and the active shutter glasses. This design includes a hardware pre-processor based on a universal edge tracer and provides a perfect sync reconstruction based on a floating-point timer to advance the prior commercial 3DTV shutter glasses in terms of their power consumption. These two techniques enable an accurate sync reconstruction in the slow clock frequency of the synchronization timer and reduce the power consumption to less than about a maximum of 20% compared with other major commercial processors. This article describes the system's architecture and the details of the proposed techniques, also identifying the key concepts and functions.

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.108-113
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• 2017

The OBCP called 'operator on board' is that of a procedure to be executed on-board, which can be easily be loaded, executed, and also replaced, without modifying the remainder of the FSW. The use of OBCP enhances the on-board autonomy capabilities and increases the robustness to ground stations outages. The OBCP engine which is the core module of OBCP component in the FSW interprets and executes of the procedures based on script language written using a high-level language, possibly compiled, and it is relying on a virtual machine of the OBCP engine. FSW team in KARI has studied OBCP since 2010 as FSW team's internal projects, and made some OBCP engines such as Java KVM, RTCS/C and KKOMA on ERC32 processor target only for study. Recently we have been studying ESA's OBCP standard and implementing Lua and MicroPython on LEON2-FT/AT697F processor target as the OBCP engine. This paper presents the design and implementation of Lua for the OBCP engine on AT697F processor with VxWorks RTOS, and describes the evaluation result and performance of the OBCP engine.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.50-58
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• 2017

Recently, some methods of converging heterogeneous fire sensor data have been proposed for effective fire detection, but the rule-based methods have low adaptability and accuracy, and the fuzzy inference methods suffer from detection speed and accuracy by lack of consideration for images. In addition, a few image-based deep learning methods were researched, but it was too difficult to rapidly recognize the fire event in absence of cameras or out of scope of a camera in practical situations. In this paper, we propose a novel fire detection system combining a deep learning algorithm based on CNN and fuzzy inference engine based on heterogeneous fire sensor data including temperature, humidity, gas, and smoke density. we show it is possible for the proposed system to rapidly detect fire by utilizing images and to decide fire in a reliable way by utilizing multi-sensor data. Also, we apply distributed computing architecture to fire detection algorithm in order to avoid concentration of computing power on a server and to enhance scalability as a result. Finally, we prove the performance of the system through two experiments by means of NIST's fire dynamics simulator in both cases of an explosively spreading fire and a gradually growing fire.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.15-25
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• 2007

This paper aims at testing the applicability of RFID (radio frequency identification) based link travel time estimation algorithm in urban street settings in Jeju island Korea. For this, we developed algorithm and compared link travel times derived from the RFID probe based algorithm with those from (already available) GPS based link travel time estimation algorithm and with the actual link travel times from survey. RFID readers are composed of master reader and slave reader and the participating passenger cars were supposed to be equipped with RFID tag inside the vehicle. The data were sent to traffic information center and we used those data in comparison. The algorithm produced link travel times in a successful manner and the accuracy of those link travel times was about 88%. For the same link segments, the accuracy of GPS based link travel times was 93%. The t-test showed that both RFID and GPS based link travel times were not different in accuracy from statistical point of view. The applicability of RFID was tested successfully and the algorithm proposed seemed to be used in similar urban settings. Some limits and future research agenda have also been presented.

• Journal of the Korean earth science society
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• v.38 no.7
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• pp.496-510
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• 2017

This study presents a new nationwide quantitative precipitation estimation (QPE) based on the hybrid surface rainfall (HSR) technique using the weather radar network of Korea Meteorological Administration (KMA). This new nationwide HSR is characterized by the synthesis of reflectivity at the hybrid surface that is not affected by ground clutter, beam blockage, non-meteorological echoes, and bright band. The nationwide HSR is classified into static (STATIC) and dynamic HSR (DYNAMIC) mosaic depending on employing a quality control process, which is based on the fuzzy logic approach for single-polarization radar and the spatial texture technique for dual-polarization radar. The STATIC and DYNAMIC were evaluated by comparing with official and operational radar rainfall mosaic (MOSAIC) of KMA for 10 rainfall events from May to October 2014. The correlation coefficients within the block region of STATIC, DYNAMIC and MOSAIC are 0.52, 0.78, and 0.69, respectively, and their mean relative errors are 34.08, 30.08, and 40.71%.