• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.664-670
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• 2018

In modern society, CCTV, which is the eye of surveillance, is being used to collect image data in various ways in daily life. CCTV is used not only for security, surveillance, and crime prevention but also in many fields such as automobile and black box. In this paper, we have developed a STM32F407 ARM chip based camera system for various applications. In order to develop camera system, modeling of camera system based on 3D structure was carried out in SolidWorks environment. The PCB board design was developed to extract the PCB parts from the camera system modeling files into iges files, convert them from the Altium Designer tool into 3D and 2D boards, After designing the camera system circuit and PCB, we have been studying the implementation of the stable system by using TRM (Thermal Risk Management) tool to cope with the heat simulation generated on the board.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.68-78
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• 2019

Recently, housing prices have surged, and the government has implemented various regulations, such as finance and taxes. Because of the policy, the nationwide housing price have stabilized, but polarization has occurred. Some argue that regulation can adversely affect the actual demand. Therefore, not only the correlation between market variables but also ripple effect of policy has to be analyzed in policy planning and analysis from a microscopic point of view. In this study, a simulation model was developed by integrating system dynamics for analyzing market structure and agent-based model for modeling decision process of market participants. This research applied the financial regulation and the tax regulation to the model and evaluated the policy effectiveness. This study reveals which feedback dominates according to the policies, which have same purpose. It is because market participants make different decision for each policy. Furthermore, there were other ripple effects not only in the policy target submarket but also in other submarket.

• Fire Science and Engineering
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• v.32 no.6
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• pp.69-73
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• 2018

This study examined the reduction effect of a hydrodynamic force acting on the vertical wall of a portable water storage tank with a convex bottom floor. For the numerical simulation, the linearized Peregrine's equation was used to analyze the lapping waves in the tank caused by water falling from a supplying nozzle. The hydrodynamic force could be calculated by measuring the maximum run-up wave height at the vertical wall. The initial conditions of the numerical experiments were set up by controlling the positions and heights of the water supplying nozzle. Finally, the hydrodynamic force acting on the vertical wall can be reduced by the convex bottom design of the portable water storage tank so it can be applied to improve the structural stability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.422-428
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• 2019

A tailless or Blended-Wing-Body(BWB) shaped configuration is highlighted for UCAV with low RCS characteristics. The BWB configuration is characterized by its directional static instability and low controllability. To control the directional movement of the BWB configured vehicle, directional thrust vectoring equipment or drag rudder typed control surfaces which utilize the drag differences of the wing can be considered. This paper deals with a BWB shaped configuration using a spoiler and describes the lateral-directional aerodynamic characteristics of the vehicle. In addition, it is shwon that the lateral-directional motion can be controlled effectively by using the classical PI control structure. This control law is verified by flight test and showed adequate for the tailless BWB shaped UAV.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.271-271
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• 2019

하천에서의 식생은 하천의 조도 및 흐름특성을 변화시키는 요인 중 하나로서 하천 내의 식생밀도 변화로 인하여 발생한 하상변동은 장기적으로 하천내의 하중도가 발생하거나, 식생으로 인해한 방향으로 편중된 흐름으로 인하여 제내지 방향으로의 하천 침식이 발생하고, 이에 따라 구조물의 안정성에 영향을 미치는 등 하천의 중 장기 계획 시 고려해야할 중요한 요인이다. 이에 따라 식생 모형을 이용한 다양한 흐름특성 분석 실험들이 수행되었으나, 대부분의 연구에서는 식생을 단순화하여 모형으로 사용하였기 때문에 실제 식생에 대한 영향성을 보기에는 한계가 존재한다. 건설기술연구원의 하천실증연구센터에서는 이러한 식생의 영향을 분석하기 위하여 네덜란드의 Deltares, 핀란드의 Aalto 대학 등과 함께 다년간 국제공동연구를 수행하였으며, 금번 소개하는 실험에서는 식생밀도에 따른 흐름변화, 하상변동 및 환경 변화 등의 검토를 목적으로 하였다. 실험은 총 2가지 유량 조건에 대하여 수행되었으며, 실험 중 흐름의 안정화를 확인하기 위하여, 유출수조에는 6개의 압력식 수위계를 설치하여 실험기간동안 유출수조에서의 수심변화를 측정하였고, 하도에는 실험구간 상 하류에 SonTek의 SL-1500 및 SL-3000을 이용하여 지속적으로 수심을 측정하고, 이 외에도 하류단에 2개의 압력식 수위 측정장비를 설치하여 수심을 모니터링하였다. 실험에 사용된 식생은 높이 약 1.5m의 2가지 밀도로 폭 2m, 길이 4m의 규모로 설치하였고, 광파기와 3차원 레이저 스캐너를 이용하여 실험 전 후의 식생 주변 및 전 실험구간의 하상을 측량하였다. 흐름특성 분석을 위한 수리 측정은 Nortek사의 Vectrino를 이용하여 측정하였고, 총 24개 측선에 대하여 각 측선별 5 ~ 10개의 유속자료를 측정하였으며, 각 측점별로 90초간 자료를 수집하였다. 흐름특성 분석에 사용된 유속자료는 이상치를 제거한 후 수행되었으며, 이상치의 제거는 표준편차의 3배 이상의 편차를 갖거나, 측정자료의 자기상관도가 70% 이하인 값들은 제거한 후 분석을 수행하였다. 흐름 분석을 위한 측정자료를 이 외에도 캠코더를 이용한 표면유속영상 측정기법과 ADCP를 이용한 측정도 병행하였으나, 본 연구에서는 Vectrino로 측정된 결과만을 소개하고자 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.101-110
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• 2003

Secure and reliable group communication is an increasingly active research area prompted by the growing popularity of many types of group-oriented and collaborative applications. The central challenge is secure and efficient group key management. While centralized methods are often appropriate for key distribution in large multicast-style groups, many collaborative group settings require distributed key agreement techniques. Most of prior group key agreement protocols have been focused on reducing the computational costs. One exception is STR protocol that optimizes communicational cost. On the other hand, it requires O(n) number of modular exponentiations. In this paper, we propose a new group key agreement protocol that modifies STR protocol by utilizing pairing based cryptography. The resulting protocol reduces computational cost of STR protocol while preserving the communication cost.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.125-136
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• 2011

The vulnerabilities existed in Korean electricity control systems is unexposed because it is being operated in a closed network with superior security. The threat will become greater once the closed network develops into a smart grid environment with superior intelligence. Security will have a greater impact once each household will be connected to the power plant via the smart meter. This research focuses on stable data transfer in harsh external environment and whole-nation coverage network, and suggested standardized and optimized Virtual Private Network (VPN) Gateway architecture to support Power Line Communication (PLC). The functionality and stability of the prototype has been verified with field tests. For implementation of outdoor type VPN device for smart grid, we adopted PLC low voltage remote-meter-net for data communication. Also, IPSec type tunneling and ARIA algorithm based encryption of data collected by PLC low voltage remote meter is transmitted.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.7
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• pp.956-962
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• 2020

Recently, as the size of data used in an embedded system increases, the need for an ECC decoding operation to robustly receive a massive data is emphasized. In this paper, we propose a method to accelerate the execution of computations that derive syndrome vectors when ECC decoding is performed using Hamming code in an embedded system with a built-in GPU. The proposed acceleration method uses the matrix-vector multiplication of the decoding operation using the CSR format, one of the data structures representing sparse matrix, and is performed in parallel in the CUDA kernel of the GPU. We evaluated the proposed method using a target embedded board with a GPU, and the result shows that the execution time is reduced when ECC decoding operation accelerated based on the GPU than used only CPU.

• Journal of Advanced Navigation Technology
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• v.26 no.4
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• pp.226-234
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• 2022

With advances in autonomous vehicles and networked control, there is a growing interest in the consensus control of a multi-agents system to control multi-agents with distributed control beyond the control of a single agent. Since consensus control is a distributed control, it is bound to have delay in a practical system. In addition, it is often difficult to have a very accurate mathematical model for a system. Even though a reinforcement learning (RL) method was developed to deal with these issues, it often experiences slow convergence in the presence of large uncertainties. Thus, we propose a slide RL which combines the sliding mode control with RL to be robust to the uncertainties. The structure of a sliding mode control is introduced to the action in RL while an auxiliary sliding variable is included in the state information. Numerical simulation results show that the slide RL provides comparable performance to the model-based consensus control in the presence of unknown time-varying delay and disturbance while outperforming existing state-of-the-art RL-based consensus algorithms.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.113-119
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• 2021

This study compared business performance and earnings quality before and after the COVID-19 pandemic for information and communication companies whose sales increased due to the impact of the COVID-19 pandemic. For this, 4 indicators of ROA, growth potential, liquidity, and stability are used for business performance, and for earnings quality, the standard deviation of the residuals measured by the Dechow and Dichev(2002) model and Francis et al.(2005) model was used. As a result of the analysis, ROA, a representative business performance indicator, increased after xthe period compared to the period before the pandemic, but liquidity was rather deteriorated. As for the quality of earnings, it was confirmed that earnings sustainability is maintained in the post-pandemic period compared to the previous period, similar to ROA. Overall, the profit level and earnings quality of information and communications companies seemed to be improving, while liquidity was deteriorating. This confirms that companies that have overcome the immediate crisis are not ready to pay off their debts right away. Therefore, it suggests that companies need restructuring to reduce their increased debt from the time the COVID-19 subsides.