• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.4
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• pp.637-659
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• 2021

Since the creation of the first Bitcoin blockchain in 2009, the number of cryptocurrency users has steadily increased. However, the number of hacking attacks targeting assets stored in these users' cryptocurrency wallets is also increasing. Therefore, we evaluate the security of the wallets currently on the market to ensure that they are safe. We first conduct threat modeling to identify threats to cryptocurrency wallets and identify the security requirements. Second, based on the derived security requirements, we utilize attack trees and Bayesian network analysis to quantitatively measure the risks inherent in each wallet and compare them. According to the results, the average total risk in software wallets is 1.22 times greater than that in hardware wallets. In the comparison of different hardware wallets, we found that the total risk inherent to the Trezor One wallet, which has a general-purpose MCU, is 1.11 times greater than that of the Ledger Nano S wallet, which has a secure element. However, use of a secure element in a cryptocurrency wallet has been shown to be less effective at reducing risks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.29-36
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• 2011

Near Field Communication is an emerging short-range wireless connectivity technology that offers proximity and different operating modes. Particularly, NFC technology has the potential to revolutionize mobile applications like payment and ticketing because NFC is more complex and mutual connectivity than RFID as the simple tag reader. Finally, NFC security technology defines the robust security protocols. This paper will specify and analyze the NFC security technology, and study the chance and its beneficial effect of the UICC card as the NFC Secure Element.

• Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.28-34
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• 2012

Structural integrity evaluation is important item in the aircraft certification. Recently, it is designed for limit load, material weakness about fatigue and corrosion, damage by bird strike in flight to evaluate structural integrity of aircraft. And static/fatigue analysis are performed to secure structural integrity, it was verified by static and fatigue tests. To evaluate the structural integrity of small aircraft tail, structural integrity was calculated by the finite element analysis. In the present study, finite element analysis are performed to pick out load cases in flight occurrence, and secure margin of safety to evaluate structural integrity of KC-100 tail unit. The proprieties of finite element analysis results are compared with the static structure test results. The estimation process of structural integrity for small aircraft tail may help the design.

• Journal of applied mathematics & informatics
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• v.41 no.4
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• pp.839-848
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• 2023

Let G be a simple undirected graph. A planar graph known as a Halin graph(HG) is characterised by having three connected and pendent vertices of a tree that are connected by an outer cycle. A subset S of V is said to be a dominating set of the graph G if each vertex u that is part of V is dominated by at least one element v that is a part of S. The domination number of a graph is denoted by the γ(G), and it corresponds to the minimum size of a dominating set. A dominating set S is called a secure dominating set if for each v ∈ V＼S there exists u ∈ S such that v is adjacent to u and S₁ = (S＼{v}) ∪ {u} is a dominating set. The minimum cardinality of a secure dominating set of G is equal to the secure domination number γ_s(G). In this article we found the secure domination number of Halin graph(HG) with perfet k-ary tree and also we determined secure domination of rooted product of special trees.

• Journal of the Korean Society of Safety
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• v.31 no.6
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• pp.1-5
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• 2016

A bicycle is one of the most popular sporting goods in view of a sport activity and a human health. Metallic materials such as steel, aluminum, etc. were mainly used to the bicycle fork in the past. Nowadays, the carbon fiber reinforced composite materials are widely used to the manufacturing of a bicycle fork to reduce the weight and to increase the efficiency. Safety is a most important design parameter of a bicycle fork even if the weight and cost reduction are important. Bicycle failure may happen at the critical spot of a bicycle fork and cause the accident. In this paper, the composite bicycle fork will be analyzed to secure the safety and detect a critical spot by using the finite element method with Tsai-Wu failure criterion. The stress data were obtained for the laminated composites with various number of plies and fiber orientation under the bending load. Thus, design concept of a bicycle fork was proposed to secure the safety of a bicycle. The finite element analysis results show that the connection area between a steer tube and a fork blade is critical spot, and 75 or more layers of 0 degree are needed to secure the safety of a bicycle fork.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.1
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• pp.151-160
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• 2024

Artificial Neural Networks that enabled Artificial Intelligence are being used in many fields. However, the application to mechanical structures has several problems and research is incomplete. One of the problems is that it is difficult to secure a large amount of data necessary for learning Artificial Neural Networks. In particular, it is important to detect and recognize external forces and forces for safety working and accident prevention of mechanical structures. This study examined the possibility by applying the Current Neural Network of Artificial Neural Networks to detect and recognize the load on the machine. Tens of thousands of data are required for general learning of Recurrent Neural Networks, and to secure large amounts of data, this paper derives load data from ANSYS structural analysis results and applies a stacked auto-encoder technique to secure the amount of data that can be learned. The usefulness of Stacked Auto-Encoder data was examined by comparing Stacked Auto-Encoder data and ANSYS data. In addition, in order to improve the accuracy of detection and recognition of load data with a Recurrent Neural Network, the optimal conditions are proposed by investigating the effects of related functions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.6
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• pp.1113-1120
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• 2022

Recently, the investigation has been difficult due to the emergence of messengers that encrypt and store data for the purpose of protecting personal information and provide services such as end-to-end encryption with a focus on security. Accordingly, the number of crime cases using security messengers is increasing, but research on data decoding for security messengers is needed. Element security messengers provide end-to-end encryption functions so that only conversation participants can check conversation history, but research on decoding them is insufficient. Therefore, in this paper, we analyze the instant messenger Element, which provides end-to-end encryption, and propose a plaintext verification of the history of encrypted secure chat rooms using decryption keys stored in the Windows Credential Manager service without user passwords. In addition, we summarize the results of analyzing significant general and secure chat-related artifacts from a digital forensics investigation perspective.

• Transactions of Materials Processing
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• v.17 no.6
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• pp.429-435
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• 2008

In this paper, the serrated forming process is analyzed with finite element method. The seal should secure the overlapping portions of ligature, which has teeth for ligature to prevent from slipping each other after clamping. In the simulation, rigid-plastic finite element model has been applied to the serration forming process. Serration or teeth forming characteristics has been analyzed numerically in terms of teeth geometry based on different forming conditions. Analyses are focused to find the influence of different die movements and geometries on the tooth geometry, which is crucial for securing overlapping portions of ligature. Two major process variables are selected, which are the face angle and entry angle of punch, respectively. Extensive investigation has been performed to reveal the influences of different entry and face angles on the geometry of teeth formation in the simulation. Three different face angles of punch have been selected to apply to each simulation of serrated sheet forming process with every case of punch entry angles. Furthermore, tooth geometries predicted from simulation have been applied to the indention process for comparing proper tooth geometries to secure the sealing.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.958-967
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• 2023

Purpose: This study aims to analyze the fire resistance performance applied to plant facilities with high fire risk in Korea, secure suitable fire resistance performance, and ensure the fire safety of plant facilities. Method: Using the finite element analysis program Ansys, thermal transfer analysis and structural analysis were performed with fire load and fireproof coating as variables, and the fire resistance performance of plant facilities was analyzed based on the analysis results. Result: The fireproof coating applied to domestic plant facilities failed to secure fire resistance performance when the fire load of hydrocarbon fire presented in UL 1709 was applied, and it was confirmed that the deformation of steel after the fire was also significant. Conclusion: The current fire resistance performance applied to plant facilities in Korea cannot secure fire resistance performance in sudden fire growth and large fire loads like petrochemical plants, and it is necessary to secure fire safety by evaluating suitable fire resistance performance through performance evaluation of plant facilities.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.94-109
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• 2006

An improved meshfree method called the Petrov-Galerkin natural element (PG-NE) method is introduced in order to secure the numerical integration accuracy. As in the Bubnov-Galerkin natural element (BG-NE) method, we use Laplace interpolation function for the trial basis function and Delaunay triangles to define a regular integration background mesh. But, unlike the BG-NE method, the test basis function is differently chosen, based on the Petrov-Galerkin concept, such that its support coincides exactly with a regular integration region in background mesh. Illustrative numerical experiments verify that the present method successfully prevents the numerical accuracy deterioration stemming from the numerical integration error.