• Design Convergence Study
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• v.15 no.1
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• pp.37-48
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• 2016

Nowadays, CAD has became an essential tool for designers due to its easy edition and manipulation as well as the capability of communication between designers. Differences between design tool interfaces can cause gaps when visualize designer's ideas. This study is about the differences between various levels of metaphor interface language which is based on the theory of the Hutchins that high-level language interface can reduce the steps of process to visualize the idea of the designers than low-level language interface. This research is based on the assumption that high-level language interface will less interrupt the flow of the design thinking and make more various visual outcomes than the low-level language interface. We verified the hypothesis by analyzing differences of design thinking flow between user groups who used two different animation software. Hopefully, the verification of the hypothesis in this study can be able to guide the use pattern of the CAD tools.

• Journal of Software Assessment and Valuation
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• v.10 no.1
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• pp.19-26
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• 2014

In this paper, we propose a method for protecting Android applications against reverse engineering attacks. In this method, the server encrypts the original executable code (DEX) included in an APK file, inserts into the APK file a stub code that decrypts the encrypted DEX later at run-time, and distributes the modified APK file. The stub code includes an integrity validation code to detect attacks on itself. When a user installs and executes the APK file, the stub code verifies the integrity of itself, decrypts the encrypted DEX, and loads it dynamically to execute. Since the original DEX is distributed as an encrypted one, we can effectively protect the intellectual property. Further, by verifying the integrity of the stub code, we can prevent malicious users from bypassing our method. We applied the method to 15 Android apps, and evaluated its effectiveness. We confirmed that 13 out of them operates normally.

• Journal of IKEEE
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• v.28 no.2
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• pp.123-130
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• 2024

As technology advances swiftly and the lifespan of products becomes increasingly short, there is a demand to fasten the pace of research outcomes, product development, and market introduction. As a result, the researchers and developers need a computational experiment environment that enables rapid verification of the experiment and application of research findings. Such an environment must efficiently harness all available computational resources, manage simulations across diverse test scenarios, and support the experimental data collection. This research introduces the design and implementation of an experimental frame based on a microservice architecture. The experimental frame leverages scripts to utilize computing resources optimally, making it more straightforward for users to conduct simulations. It features an experimental frame capable of automatically deploying scenarios to the computing components. This setup allows for the automatic configuration of both the computing environment and experiments based on user-provided scenarios and experimental software, facilitating effortless execution of simulations.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.386-392
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• 2024

This paper constructs a precise dynamics model using flightlab, a specialized program for rotor modeling and performance analysis, to simulate urban air mobility (UAM). flightlab is well-suited for detailed modeling of UAM, particularly requiring detailed aerodynamic characteristics under high-altitude and urban wind conditions. The study focuses on implementing and analyzing a lift-cruise UAM model with distributed propulsion using flightlab. The lift-cruise model integrates motors for vertical take-off and fixed-wing flight. Given the limited specific examples of such UAM models in flightlab and challenges in evaluating with conventional fixed-wing or drone models, this research implements and verifies the lift-cruise model using matlab, comparing its performance against flightlab results to validate the modeling approach. This research aims to explore the potential of flightlab for detailed UAM modeling and contribute to technological advancements in future urban transportation.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.9
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• pp.375-384
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• 2021

Deep learning techniques have been proven to have high performance in image processing and are applied in various fields. The most widely used methods for validating a deep learning model include a holdout verification method, a k-fold cross verification method, and a bootstrap method. These legacy methods consider the balance of the ratio between classes in the process of dividing the data set, but do not consider the ratio of various features that exist within the same class. If these features are not considered, verification results may be biased toward some features. Therefore, we propose a deep learning model validation method based on data feature coverage for image classification by improving the legacy methods. The proposed technique proposes a data feature coverage that can be measured numerically how much the training data set for training and validation of the deep learning model and the evaluation data set reflects the features of the entire data set. In this method, the data set can be divided by ensuring coverage to include all features of the entire data set, and the evaluation result of the model can be analyzed in units of feature clusters. As a result, by providing feature cluster information for the evaluation result of the trained model, feature information of data that affects the trained model can be provided.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1071-1077
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• 2022

A security SoC that can be used to implement elliptic curve cryptography (ECC) based public-key infrastructures was designed. The security SoC has an architecture in which a hardware accelerator for the elliptic curve digital signature algorithm (ECDSA) is interfaced with the Cortex-A53 CPU using the AXI4-Lite bus. The ECDSA hardware accelerator, which consists of a high-performance ECC processor, a SHA3 hash core, a true random number generator (TRNG), a modular multiplier, BRAM, and control FSM, was designed to perform the high-performance computation of ECDSA signature generation and signature verification with minimal CPU control. The security SoC was implemented in the Zynq UltraScale+ MPSoC device to perform hardware-software co-verification, and it was evaluated that the ECDSA signature generation or signature verification can be achieved about 1,000 times per second at a clock frequency of 150 MHz. The ECDSA hardware accelerator was implemented using hardware resources of 74,630 LUTs, 23,356 flip-flops, 32kb BRAM, and 36 DSP blocks.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2500-2505
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• 2007

The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compact and environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the electromagnetic behaviors of high-current vacuum arcs for two different types of AMF contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.

• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.863-868
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• 2005

Hardware and software codesign framework called PeaCE(Ptolemy extension as a Codesign Environment) was developed. It allows to express both data flow and control flow which is described as fFSM which extends traditional finite state machine. While the fFSM model provides lots of syntactic constructs for describing control flow, it has a lack of their formality and then difficulties in verifying the specification. In order to define the formal semantics of the fFSM, in this paper, firstly the hierarchical structure in the model is flattened and then the step semantics is defined. As a result, some important bugs such as race condition, ambiguous transition, and circulartransition can be formally detected in the model.

• Journal of KIISE:Software and Applications
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• v.26 no.8
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• pp.988-999
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• 1999

본 논문은 SCR 방법으로 작성된 요구사항 명세의 정형적인 의미론을 제안한다. 먼저 우리는 SCR 명세를 시간적전이시스템으로 변환함으로써 SCR 명세의 의미론을 정의한다. 그리고 우리는 SCR 방법을 실시간 시스템의 명세를 위하여 확장하며, 확장된 SCR 명세의 의미론 또한 시간적전이시스템으로의 변환을 통하여 정의한다. 이러한 의미론은 SCR 명세의 병행성과 시간 개념을 제대로 나타낼 수 있으며, 시간적전이시스템에서의 검증 방법을 SCR 명세의 검증에 직접 적용할 수 있게 하는 장점이 있다.Abstract This paper presents a formal semantics for requirements specifications written in the SCR method. We define a semantics for SCR specifications by a translational approach into timed transition systems. Then we extend the SCR method for real-time systems and define a semantics for timed SCR specifications. The main benefit from providing such semantics is that it provides a natural modeling of concurrency and time in SCR specifications. The semantics enables us to directly apply verification methods for timed transition systems to SCR specifications.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.269-281
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• 2014

This paper examines the suitability of using the Computational Fluid Dynamics (CFD) tools, ANSYS-CFX, as an initial analysis tool for predicting the drag and propulsion performance (thrust and torque) of a concept underwater vehicle design. In order to select an appropriate thruster that will achieve the required speed of the Underwater Disk Robot (UDR), the ANSYS-CFX tools were used to predict the drag force of the UDR. Vertical Planar Motion Mechanism (VPMM) test simulations (i.e. pure heaving and pure pitching motion) by CFD motion analysis were carried out with the CFD software. The CFD results reveal the distribution of hydrodynamic values (velocity, pressure, etc.) of the UDR for these motion studies. Finally, CFD bollard pull test simulations were performed and compared with the experimental bollard pull test results conducted in a model basin. The experimental results confirm the suitability of using the ANSYS-CFX tools for predicting the behavior of concept vehicles early on in their design process.