• 정보보호학회논문지
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• 제14권2호
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• pp.101-111
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• 2004

ISP 네트워크의 보안수준 진단과 대응방안을 수립하기 위해서는 네트워크상의 정보자산에 대한 취약점과 위협 요인을 식별하고, 피해 발생시 예상되는 손실의 정도를 산정하는 위험분석 절차가 필수적이다. 하지만, 기존의 위험분석 방법론 및 도구들은 대부분 방법론적 분석절차와 수단만을 제공하며, 개별 시스템의 취약점 및 위협요인의 변동정보를 실시간으로 반영할 수가 없다. 따라서. 본 논문에서는 네트워크 침입탐지 시스템과 취약점 분석 시스템의 탐지 정보들을 실시간으로 수집, 분석하여 네트워크 자산에 발생할 수 있는 위험의 가능성을 찾아내고, 정량적인 위험수준을 평가하는 시스템을 제안한다. 또한, 실험을 통해 시스템의 성능수준을 제시하였다.

• Structural Engineering and Mechanics
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• 제76권6호
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• pp.675-685
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• 2020

As the classical response surface method (RSM), the polynomial RSM is so easy-to-apply that it is widely used in reliability analysis. However, the trade-off of accuracy and efficiency is still a challenge and the "curse of dimension" usually confines RSM to low dimension systems. In this paper, based on the univariate decomposition, the polynomial RSM is executed in a new mode, called as DPRSM. The general form of DPRSM is given and its implementation is designed referring to the classical RSM firstly. Then, in order to balance the accuracy and efficiency of DPRSM, its adaptive order revision around the most probable point (MPP) is proposed by introducing the univariate polynomial order analysis, noted as RDPRSM, which can analyze the exact nonlinearity of the limit state surface in the region around MPP. For testing the proposed techniques, several numerical examples are studied in detail, and the results indicate that DPRSM with low order can obtain similar results to the classical RSM, DPRSM with high order can obtain more precision with a large efficiency loss; RDPRSM can perform a good balance between accuracy and efficiency and preserve the good robustness property meanwhile, especially for those problems with high nonlinearity and complex problems; the proposed methods can also give a good performance in the high-dimensional cases.

• International Journal of Computer Science & Network Security
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• 제22권7호
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• pp.352-358
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• 2022

Text mining is an important process used for analyzing the data collected from different sources like videos, audio, social media, and so on. The tools like Natural Language Processing (NLP) are mostly used in real-time applications. In the earlier research, text mining approaches were implemented using long-short memory (LSTM) networks. In this paper, text mining is performed using average-stochastic gradient descent weight-dropped (AWD)-LSTM techniques to obtain better accuracy and performance. The proposed model is effectively demonstrated by considering the internet movie database (IMDB) reviews. To implement the proposed model Python language was used due to easy adaptability and flexibility while dealing with massive data sets/databases. From the results, it is seen that the proposed LSTM plus weight dropped plus embedding model demonstrated an accuracy of 88.36% as compared to the previous models of AWD LSTM as 85.64. This result proved to be far better when compared with the results obtained by just LSTM model (with 85.16%) accuracy. Finally, the loss function proved to decrease from 0.341 to 0.299 using the proposed model

• 전력전자학회논문지
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• 제27권2호
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• pp.165-173
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• 2022

The electrification trend of mobility increases every year due to the development of power semiconductor and battery technology. Accordingly, the development and distribution of fast chargers for electric vehicles (EVs) are in demand. In this study, we propose a design and implementation method of an LLC converter for fast chargers. Two 15 kW LLC converters are configured in parallel to have 30 kW rated output power, and the control algorithm and driving sequence are designed accordingly and verified. In addition, the improved power conversion efficiency is confirmed through zero-voltage switching (ZVS) of the LLC converter and reduction of turn-off loss through snubber capacitors. The implemented 30 kW LLC converters show a wide output voltage range of 200-950 V. Experiments applying various load conditions verify the converter performance.

• Journal of Information Processing Systems
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• 제18권2호
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• pp.258-267
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• 2022

Weak over-the-horizon perception and blind spot are the main problems in intelligent connected vehicles (ICVs). In this paper, a V2V image transmission-based road condition warning method is proposed to solve them. The encoded road emergency images which are collected by the ICV are transmitted to the on-board unit (OBU) through Ethernet. The OBU broadcasts the fragmented image information including location and clock of the vehicle to other OBUs. To satisfy the channel quality of the V2X communication in different times, the optimal fragment length is selected by the OBU to process the image information. Then, according to the position and clock information of the remote vehicles, OBU of the receiver selects valid messages to decode the image information which will help the receiver to extend the perceptual field. The experimental results show that our method has an average packet loss rate of 0.5%. The transmission delay is about 51.59 ms in low-speed driving scenarios, which can provide drivers with timely and reliable warnings of the road conditions.

• Structural Engineering and Mechanics
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• 제81권6호
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• pp.769-780
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• 2022

This paper studies the dynamic behavior of laminated composite circular cylindrical shells interacting with a fluid. The mathematical formulation of the dynamic problem for an elastic body is developed based on the variational principle of virtual displacements and the relations of linear elasticity theory. The behavior of an ideal compressible fluid is described by the potential theory, the equations of which together with boundary conditions are transformed to a weak form. The hydrodynamic pressure exerted by the fluid on the internal surface of the shell is calculated according to the linearized Bernoulli equation. The numerical implementation of the mathematical formulation has been done using the semi-analytical finite element method. The influence of the ply angle and lay-up configurations of laminated composites on the natural vibration frequencies and the hydroelastic stability boundary have been analyzed for shells with different geometrical dimensions and under different kinematic boundary conditions set at their edges. It has been found that the optimal value of the ply angle depends on the level of filling of the shell with a fluid. The obtained results support the view that by choosing the optimal configuration of the layered composite material it is possible to change upwards or downwards the frequency and mode shape, as well as the critical velocity for stability loss over a wide range.

• Steel and Composite Structures
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• 제47권4호
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• pp.467-488
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• 2023

Seismic retrofit of an existing steel-reinforced concrete hospital building that features innovative use of a continuous energy-dissipative steel column (CEDC) system is presented in this paper. The special system has been adopted to provide an efficient solution taking into account the difficulties of applying traditional intervention techniques to minimize the impact on architectural functionality and avoid the loss of building function and evacuation during the retrofit implementation. The lateral stiffness and strength of the CEDC system were defined based on the geometric and mechanical properties of the steel strip dampers. The hysteretic behavior under cyclic loadings was defined using a simplified numerical model. Its effectiveness was validated by comparing the results of full-scale experimental data available from the literature. All the main design considerations of the retrofitting plan are described in detail. The effectiveness of the proposed retrofitting system was demonstrated by nonlinear time-history analyses under different sets of earthquake-strong ground motions. The analysis results show that the CEDC system is effective in controlling the deformation pattern and significantly reducing damage to the existing structure during major earthquakes.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.126-129
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• 2021

기존의 배수설비 관리 시스템은 체계적으로 전산화되어 있지 않으며, 각 배수설비의 정보 및 위치 관리가 미흡하여 현장에서의 관리에 어려움을 겪고 있다. 현재 배수설비 관리에서는 수리 기사가 현장에서 QR코드를 인식하여 배수설비의 정보를 파악하고 있다. 이러한 방법은 현장에서 QR코드의 위치를 찾는데 어려움이 있고, QR코드 부착물의 분실 및 파손으로 인해 추가적인 유지보수비용이 든다는 문제점이 있다. 본 논문에서 제안하는 GPS 기반 배수설비 관리 시스템은 각 배수설비를 GPS 정보를 포함하여 저장, 관리하므로 현장에서 어플리케이션을 통해 사용자의 위치 데이터를 기반으로 배수설비의 위치 및 정보를 제공하는 방법을 사용할 수 있고, 웹 기반 관리 시스템에서 배수설비 및 하수관거 민원, 시설물의 관리를 함께 하여 배수설비 관리의 효율을 증가시킬 수 있다.

• Journal of Information Technology Applications and Management
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• 제30권6호
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• pp.69-80
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• 2023

Ship collision accidents not only cause loss of life and property damage, but also cause marine pollution and can become national disasters, so prevention is very important. Most of these ship collision accidents are caused by human factors due to the navigation officer's lack of vigilance and carelessness, and in many cases, they can be prevented through the support of a system that helps with situation awareness. Recently, artificial intelligence has been used to develop systems that help navigators recognize the situation, but the sea is very wide and deep, so it is difficult to secure maritime traffic datasets, which also makes it difficult to develop artificial intelligence models. In this paper, to solve these difficulties, we propose a method to build a dataset with characteristics similar to actual maritime traffic datasets. The proposed method uses segmentation and inpainting technologies to build a foreground and background dataset, and then applies compositing technology to create a synthetic dataset. Through prototype implementation and result analysis of the proposed method, it was confirmed that the proposed method is effective in overcoming the difficulties of dataset construction and complementing various scenes similar to reality.

• 한국산업융합학회 논문집
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• 제26권5호
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• pp.867-874
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• 2023

In this paper, a wireless communication-based sensor data monitoring device with an explosion-proof (Exd IIC) case was implemented to enable installation at explosion-risk industrial sites such as plants. In existing industrial plant sites, most of the temperature sensors and vibration and impact sensors are wired up to several kilometers, which takes a lot of time and money to bury long pipes and cables. In addition, there are not many cases where some wireless devices have been applied to actual plant industry sites due to communication quality problems. Therefore, in order to solve this problem, zigbee mesh wireless communication was applied to provide high reliability wireless communication quality to industrial plant sites, and the time and cost incurred in new or additional installation of sensors could be greatly reduced. In particular, in the event of loss or error of some wireless communication devices, the communication network is automatically bypassed or recovered to enable real-time data monitoring.