• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.4
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• pp.21-28
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• 2006

The proportional control solenoid valves as well as the PWM solenoid valves operated by electric signal play an important role in the hydraulic system for automatic transmissions to improve the shift quality. However it is not generally available for the performance data because most of the automotive parts manufacturer don't release the specific test results, especially dynamic performance that is essential to design a shift control algorithm. In this research, a performance test equipment that can be applied to various types of pressure control solenoid valve was developed. It was implemented by 8-bit micro-controller with many useful functions such as adjustable PWM carrier frequency, embedded function generator, current controller, data monitoring and acquisitions, etc. for the test of dynamic performance of solenoid valve as well as the steady-state pressure characteristics. The performance test results for the direct type proportional control solenoid valve show not only the validity of overall functions but also its usefulness as a hydraulic valve tester.

• International journal of advanced smart convergence
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• v.8 no.1
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• pp.141-146
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• 2019

These days, there are many applications using neural networks as parts of their system. On the other hand, adversarial examples have become an important issue concerining the security of neural networks. A classifier in neural networks can be fooled and make it miss-classified by adversarial examples. There are many research to encounter adversarial examples by using denoising methods. Some of them using GAN (Generative Adversarial Network) in order to remove adversarial noise from input images. By producing an image from generator network that is close enough to the original clean image, the adversarial examples effects can be reduced. However, there is a chance when adversarial noise can survive the approximation process because it is not like a normal noise. In this chance, we propose a research that utilizes high-level representation in the classifier by combining GAN network with a trained U-Net network. This approach focuses on minimizing the loss function on high representation terms, in order to minimize the difference between the high representation level of the clean data and the approximated output of the noisy data in the training dataset. Furthermore, the generated output is checked whether it shows minimum error compared to true label or not. U-Net network is trained with true label to make sure the generated output gives minimum error in the end. At last, the remaining adversarial noise that still exist after low-level approximation can be removed with the U-Net, because of the minimization on high representation terms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.826-828
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• 2014

Recently trend of product is miniaturization. As a result, We need products surface as well as products internal defect inspection. Generally, Inspection products in production process uses a lot of optical inspection. However, This is difficult to internal inspection of products. We used optical device instead of X-ray generator. At the same time, We have developed system to determine the product defect. First, obtain X-ray image from Machine vision function. Next, Measured value is recognize suitability within error range. otherwise recognize defect. Results presence of defective products can be stored by user.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.45-53
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• 2019

Thermal-hydraulic passive safety systems (PSSs) are incorporated into many advanced reactor designs on the bases of simplicity, economics and inherent safety nature. Several factors among which are the critical parameters (CPs) that influence failure and reliability of thermal-hydraulic (t-h) passive systems are now being explored. For simplicity, it is assumed in most reliability analyses that the CPs are independent whereas in practice this assumption is not always valid. There is need to critically examine the dependency influence of the CPs on reliability of the t-h passive systems at design stage and in operation to guarantee safety/better performance. In this paper, two multivariate analysis methods (covariance and conditional subjective probability density function) were presented and applied to a simple PSS. The methods followed a generalized procedure for evaluating t-h reliability based on dependency consideration. A passively water-cooled steam generator was used to demonstrate the dependency of the identified key CPs using the methods. The results obtained from the methods are in agreement and justified the need to consider the dependency of CPs in t-h reliability. For dependable t-h reliability, it is advisable to adopt all possible CPs and apply suitable multivariate method in dependency consideration of CPs among other factors.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.3
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• pp.317-327
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• 2021

Low Frequency Active Sonobuoy(hereinafter referred to as LFAS) are being developed in Korea in consideration of compatibility with existing overseas sonobuoys, and a communication device for acoustic signals receiving and operating control of LFAS has been developed. The communication device needs to verify compatibility with the existing Sonobuoy, and for this purpose, the standardized Sonobuoy communication protocol was applied. The communication device is designed/manufactured to transmit the acoustic signal received in real time from the Sonobuoy through VHF band RF communication to the data processing device, and transmit CFS/CSG commands for operation control to the Sonobuoy through UHF band RF communication. In order to verify the manufactured communication device, the communication status and performance were verified by interlocking test through Ultra Electronics' PASS-II equipment and domestically developed electronic device of Sonobuoy. In addition, operability was verified through environmental tests, water tanks, and marine operations. In the future, the communication device of sonobuoy can be used for verification of the Sonobuoy developed in Korea.

• Journal of Practical Engineering Education
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• v.13 no.3
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• pp.497-505
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• 2021

Test equipment for strain and vibration measurement was designed for educational purposes. Widely available and affordable materials were put into making this device. Three strain gauges placed on an iron ruler made cantilevered beam were used to measure values according to external load. An electromagnet triggered excitation and a function generator created vibration of the beam. We present three different tests conducted with this equipment regarding production of scales, measurement of resonant frequency, and calculation of the difference between excitation frequency and measured frequency. Overall, this paper presents a piece of simple yet inexpensive test equipment and its corresponding portfolio with expectations of being applied to the educational field for efficient measurement of load and vibration.

• ETRI Journal
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• v.45 no.2
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• pp.346-357
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• 2023

Hardware security primitives, also known as physical unclonable functions (PUFs), perform innovative roles to extract the randomness unique to specific hardware. This paper proposes a novel hardware security primitive using a commercial off-the-shelf flash memory chip that is an intrinsic part of most commercial Internet of Things (IoT) devices. First, we define a hardware security source model to describe a hardware-based fixed random bit generator for use in security applications, such as cryptographic key generation. Then, we propose a hardware security primitive with flash memory by exploiting the variability of tunneling electrons in the floating gate. In accordance with the requirements for robustness against the environment, timing variations, and random errors, we developed an adaptive extraction algorithm for the flash PUF. Experimental results show that the proposed flash PUF successfully generates a fixed random response, where the uniqueness is 49.1%, steadiness is 3.8%, uniformity is 50.2%, and min-entropy per bit is 0.87. Thus, our approach can be applied to security applications with reliability and satisfy high-entropy requirements, such as cryptographic key generation for IoT devices.

• Journal of the Korean Society of Safety
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• v.38 no.1
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• pp.18-24
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• 2023

Severe natural disasters and man-made attacks such as terrorism are causing unprecedented disruptions in power systems. Due to rapid climate change and the aging of energy infrastructure, both the frequency of failure and the level of damage are expected to increase. Resilience is a concept proposed to respond to extreme disaster events that have a low probability of occurrence but cause enormous damage and is defined as the ability of a system to recover to its original function after a disaster. Resilience is a comprehensive indicator that can include system performance before and after a disaster and focuses on preparing for all possible disaster scenarios and having quick and efficient recovery actions after an incident. Various studies have been conducted to evaluate resilience, but studies on economic damage considering the duration of a power outage are scarce. In this study, we propose an optimal algorithm that can identify failures after an extreme disaster and restore the load on the distribution system through emergency distributed power generation input and system reconfiguration. After that, the cost of power outage damage is analyzed by applying VoLL and CDF according to each restoration strategy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.127-130
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• 2022

This paper is a study on singing voice synthesis modeling using a generator loss function, which analyzes various factors that may occur when applying BEGAN among deep learning algorithms optimized for image generation to Audio domain. and we conduct experiments to derive optimal quality. In this paper, we focused the problem that the L1 loss proposed in the BEGAN-based models degrades the meaning of hyperparameter the gamma(𝛾) which was defined to control the diversity and quality of generated audio samples. In experiments we show that our proposed method and finding the optimal values through tuning, it can contribute to the improvement of the quality of the singing synthesis product.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.2
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• pp.48-54
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• 2014

For the element ${\alpha}{\in}GF(p^n)$, two kinds of bases are known. One is a conventional polynomial basis of the form $\{1,{\alpha},{\alpha}^2,{\cdots},{\alpha}^{n-1}\}$, and the other is a normal basis of the form $\{{\alpha},{\alpha}^p,{\alpha}^{p^2},{\cdots},{\alpha}^{p^{n-1}}\}$. In this paper we consider the method of generating normal bases which construct the finite field $GF(p^n)$, as an n-dimensional extension of the finite field GF(p). And we analyze the code sequence generating algorithm and derive the implementation functions of code sequence generator based on the normal bases. We find the normal polynomials of degrees, n=5 and n=7, which can generate normal bases respectively, design, and construct the code sequence generators based on these normal bases. Finally, we produce two code sequence groups(n=5, n=7) by using Simulink, and analyze the characteristics of the autocorrelation function, $R_{i,i}(\tau)$, and crosscorrelation function, $R_{i,j}(\tau)$, $i{\neq}j$ between two different code sequences. Based on these results, we confirm that the analysis of generating algorithms and the design and implementation of the code sequence generators based on normal bases are correct.