• Journal of Korea Society of Industrial Information Systems
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• v.14 no.4
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• pp.16-29
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• 2009

This paper investigates the kinematic and dynamic analysis of a spherical three degree of freedom parallel joint module, which is used in the exercise equipment for balance and leg-strength improvement of aged people. The joint module has three dyads which consist of two links and three revolute joints, and their all joints intersect at the global point located at the module's center. The paper shows the explicit mathematical procedure for deriving the closed form solutions in the inverse and forward position analysis of this parallel joint module. In velocity and acceleration analysis, we derived relations for joint velocities and accelerations of dyads and rotational velocity and acceleration of the top plate. For applying this module to rehabilitation exercise, we determined the dynamic model of the Korean males in their 50s and examined the model's results by dynamic model simulation.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.23-29
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• 2022

Recently, due to the increase in the use of Internet of Things (IoT) devices, the amount of data transmitted and processed to cloud computing servers has increased rapidly. As a result, network problems (delay, server overload and security threats) are emerging. In particular, edge computing with lower computational capabilities than cloud computing requires a lightweight authentication algorithm that can easily authenticate numerous IoT devices.In this paper, we proposed a key-agreement protocol of a lightweight algorithm that guarantees anonymity and forward and backward secrecy between IoT and edge devices. and the proposed algorithm is stable in MITM and replay attacks for edge device and IoT. As a result of comparing and analyzing the proposed key-agreement protocol with previous studies, it was shown that a lightweight protocol that can be efficiently used in IoT and edge devices.

• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.150-158
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• 2022

This paper presents the results of a sea trial for very long range spread spectrum underwater acoustic communication conducted in the East Sea in September 2021. Signals were collected through 8 vertical sensors, and the range between the transmitter and receiver was about 160 km. 30 bps Multi-Code Spread Spectrum (MCSS) method and 100 bps Chirp Spread Spectrum method were used for the transmitting signal generation. The results show that when the channel coding technique was not used in a single channel, the uncoded bit error rate was high, but when the Equal Gain Combining (EGC) diversity technique was used after frame synchronization in each receiving channel, the uncoded bit error rate was reduced to 0.1 or less.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.11
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• pp.71-79
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• 2017

In this paper, we implemented the exchange rate forecasting neural network using heterogeneous computing. Exchange rate forecasting requires a large amount of data. We used a neural network that could leverage this data accordingly. Neural networks are largely divided into two processes: learning and verification. Learning took advantage of the CPU. For verification, RTL written in Verilog HDL was run on FPGA. The structure of the neural network has four input neurons, four hidden neurons, and one output neuron. The input neurons used the US $ 1, Japanese 100 Yen, EU 1 Euro, and UK £ 1. The input neurons predicted a Canadian dollar value of $ 1. The order of predicting the exchange rate is input, normalization, fixed-point conversion, neural network forward, floating-point conversion, denormalization, and outputting. As a result of forecasting the exchange rate in November 2016, there was an error amount between 0.9 won and 9.13 won. If we increase the number of neurons by adding data other than the exchange rate, it is expected that more precise exchange rate prediction will be possible.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.5
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• pp.761-773
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• 2023

This paper proposes a method to increase the power-analysis resistance of the neural network model's feedforward process by replacing the exponential-based activation function, used in the deep-learning field, with an approximated function especially at the multi-layer perceptron model. Due to its nature, the feedforward process of neural networks calculates secret weight and bias, which already trained, so it has risk of exposure of internal information by side-channel attacks. However, various functions are used as the activation function in neural network, so it's difficult to apply conventional side-channel countermeasure techniques, such as masking, to activation function(especially, to exponential-based activation functions). Therefore, this paper shows that even if an exponential-based activation function is replaced with approximated function of simple form, there is no fatal performance degradation of the model, and than suggests a power-analysis resistant feedforward neural network with exponential-based activation function, by masking approximated function and whole network.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.515-525
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• 2024

Dark patterns refer to intentionally deceptive design techniques used by online service providers to hide necessary information, preventing users from taking desired actions or luring them into unintended behaviors. In this study, we analyzed the prevalence of dark patterns such as banners, advertorials, pop-ups, and video ads, and their impact on users across the top 200 news websites worldwide. The research revealed that there is a minimal correlation between banner ads and user bounce rates or unique visitors. Consequently, the main screen moving banner and headline news screen moving banner were most frequently observed in South America, while the headline news screen fixed banner was most commonly observed in Asia. All other categories were predominantly observed in Europe, making European websites the most diverse and abundant in various dark patterns.

• Journal of the Korean Society of Radiology
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• v.82 no.3
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• pp.682-687
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• 2021

Systemic-to-pulmonary artery fistulas are rare. This condition may be congenital, post-traumatic, or post-inflammatory and can cause infection, hemorrhage, or pulmonary hypertension. Here, we report a case of an intercostal-to-pulmonary artery fistula, incidentally detected during the evaluation of dyspnea in a 67-year-old female. Retrograde transcatheter coil embolization in a dilated draining pulmonary artery was initially attempted. However, another draining pulmonary artery developed after 5 months. The intercostal arteries or systemic feeders were successfully embolized through a transarterial access. At the 10-month follow-up, the abnormally dilated vessels had regressed, and dyspnea had improved. Sequential or simultaneous retro- and antegrade transcatheter embolization may successfully treat pleural arterio-arterial fistulas.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.657-665
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• 2019

In this study, we conducted a study on the transcranial magnetic electrode, a method for the study of dementia and muscle pain, a neurodegenerative disease caused by an aging society, which is becoming a problem worldwide. In particular, transcranial magnetic electrodes have been studied to improve their ability to be deteriorated by dementia symptoms such as speech, cognitive ability, and memory by outputting magnetism deep into the brain using coils on the head epidermis. In this study, simulation was performed using Maxwell 3D program for the design of coil, the core of transcranial magnetic electrode. As a result of the simulation comparison between the coil designed by the previous research and the coil through the research and development, the output was found to be superior to the conventional designed coil. The graphs of the coil outputs of B-Field and H-Field are found to be symmetrical, but the symmetry between each coil is pseudo-symmetrical and not accurate. Based on these results, an experiment was conducted to confirm whether the output of the head epidermis through both coils is possible. In the magnitude field of the reverse-coil 2-coil analysis, the maximum output was 3.3920e + 004 H [A_per_meter], and the vector field showed the strongest magnetic field around 35 to 165 degrees. It was confirmed that the magnetic output canceled due to the magnetic output. In the case of the forward 2-coil, a maximum of 3.2348e + 004H [A_per_meter] similar to the reverse coil was observed, but in the case of the vector field, the magnetic output regarding the forward output and the head skin output was confirmed. However, when the height change in the output coil, the magnetic output was reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.351-360
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• 2016

The purpose of this study is to predict visual-spatial working memory performance through the characteristics of an electroencephalogram (EEG) in the resting state. The 31 study participants, middle school students with various to academic performance, were underwent visual-spatial working memory test in the Comprehensive Attention Test (CAT) on December in 2014. Each 7 and 6 participants were divided into an Excellent Working Memory (EWM) group and Poor Working Memory (PWM) group depending on the forward/backward working memory scores. The EEG measurements and analysis of the data from a Brain Function Tester were performed by the two groups. A Mann-Whitney Test was used to examine the statistical differences between them. The activation of high beta (${\beta}H$) at the Fp1 and Fp2 sites in the left and right hemisphere, and that of the low beta (${\beta}L$) in the right hemisphere in the EWM group was significantly higher than that in the PWM group. In conclusion, there is a correlation between the visual-spatial working memory performance and the activation of ${\beta}H$ and ${\beta}L$ in the resting state and a close correlation that of ${\beta}L$ in the right hemisphere in terms of mental activity and faculty. Therefore, the visual-spatial working memory performance can be predicted by the activation of ${\beta}H$ and ${\beta}L$ in the resting state. The activation of EEG can be applied as an assessment tool and provide basis data for visual-spatial working memory performance.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.640-644
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• 1998

We have fabricated Sb/SiC(4H) Schottky barrier diode (SBD) of which characteristics compared with that of Ti/SiC(4H) SBD. The donor concentration of the n-type SiC(4H) obtained by capacitance-voltage (C-V) measurement was about $2.5{\times}10 ^{17}{\textrm}cm^{-3}$. The ideality factors of 1.31 was obtained from the slope of forward current-voltage (I-V) characteristics of Sb/SiC(4H) SBD at low current density. The breakdown field of Sb/SiC(4H) SBD under the reverse bias voltage was about $4.4{\times}10^2V$/cm. The built-in potential and the Schottky barrier height (SBH) of Sb/SiC(4H) SBD were 1.70V and 1.82V, respectively, which were determined by the analysis of C-V characteristics. The Sb/SiC(4H) SBH of 1.82V was higher than Ti/SiC(4H) SBH of 0.91V. However, the current density and reverse breakdown field of Sb/SiC(4H) were low as compared with those of Ti/SiC(4H). The Sb/SiC(4H), as well as the Ti/SiC(4H), can be utilized as the Shottky barrier contact for the high-power electronic device.