• Applied Science and Convergence Technology
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• v.25 no.6
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• pp.133-137
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• 2016

The surface treatment of cover glass for conversion efficiency of photovoltaic cell is important to reduce reflectivity and to increase the incident light. In this work, random textured anti glare (RTAG) glass was prepared by wet surface coating method. Optical properties due to the changes of surface morphology of RTAG glass were compared and conversion efficiency of photovoltaic cell was researched. Grain size and changes of surface morphologies formed with surface etching time greatly affected optical transmittance and transmission haze. Current density (Jsc) were high at the condition when surface morphologies reflection haze were low and transmission haze were high. Jsc was $40.0mA/cm^2$ at glancing angle of $90^{\circ}$. Incidence light source was strongly influenced by surface treatment of cover glass at high incidence angle but was hardly affected light source at the low angle of incidence.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.85-89
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• 2004

The wave interactions with fully submerged and floating dual buoy/vertical porous membrane breakwaters has been investigated in experimentally to validate the developed theory and numerical method in the previous study, in which multi-domain hydro-elastic formulation was carried out in the context of linear wave-body interaction theory and Darcy's law. It is found that the experimental results agrees well with the numerical prediction. Transmission and reflection can be quite reduced simultaneously especially in the region of long waves. The properly tuned system to incoming waves can effectively dissipate wave energy and also offset each other between incident and scattered waves using its hydro-elasticity and geometry.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.9-14
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• 1993

We chose Bessel beamu[$J_o(ar)}$)l in order to investigate image forming property of the optical system with combined filter of amplitude and phase(CFAP). This paper investigated numerically the influence of number of nodes of these beams on the PSF, encircled energy(E), transmission ratio(TR), gain((;) for an aberrated(1aberration-free) optical system. These results showed that the property of PSF differ considerably from the one of the existing amplitude filter and that Bessel beam has super compensating effect for an optical system with spherical aberration. Particularly, the Bessel beam has less the size of central spot than the radius of Airy disk, this result can therefore be applied to the fabrication of semiconductor device.

• Proceedings of the KIEE Conference
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• summer
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• pp.803-805
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• 2004

This paper proposes the calculation method of magnetic coupling coefficient of the contact-less energy transmission system by 3D finite element method with a variation of the secondary core positions. The primary, secondary self and leakage inductances and the capacitances of a resonant circuit are calculated by the finite element analysis results. From these values, the magnetic coupling coefficients are obtained. The secondary voltages and currents at the secondary core positions are calculated by using the resonant circuit and compared.

• Journal of IKEEE
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• v.23 no.1
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• pp.306-309
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• 2019

Wireless charging is a technology of transmitting power through an air gap to an electrical load for the purpose of energy dissemination. Compared to traditional charging with code, wireless power charging has many benefits of avoiding the hassle from connecting cables, rendering the design and fabrication of much smaller devices without the attachment of batteries, providing flexibility for devices, and enhancing energy efficiency, etc. A transmitting coil and a receiving coil for inductive coupling or magnetic resonant coupling methods are available for the near field techniques, but are not for the far field one. In this paper, the wireless power transfer (WPT) circuit by using magnetic resonant coupling method with a resonant frequency of 13.45 Mhz for the low power system is implemented to measure the power transmission efficiency in terms of mutual distance and omnidirectional angles of receiver.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.45-52
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• 2020

In this study, performance experiments were performed on the shape of steel dampers that affect the rocking behavior. Three types of strut shapes of SI type, SV type and SS type were considered as experimental variables. As a result of the experiment, the capacity to resist the moment and drift ratio according to the strut shape of the steel damper was evaluated as very close. Finally, it was evaluated that the SV type steel damper has stable deformation and energy dissipation capability. As a result of the evaluation of the proposed damper transmission force, it is considered that the damper transmission force is evaluated larger than the applied horizontal force, and it is necessary to supplement it.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.10
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• pp.3256-3274
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• 2022

With the rapid development of information and communications technology, the construction of efficient, reliable, and safe Internet of Things (IoT) is an inevitable trend in order to meet high-quality demands for the forthcoming 6G communications. In this paper, we study a secure intelligent reflecting surface (IRS)-assisted IoT system where malicious eavesdropper trying to sniff out the desired information from the transmission links between the IRS and legitimate IoT devices. We discuss the system overall performance and propose a hybrid resource allocation scheme for maximizing the secrecy capacity and secrecy energy efficiency. In order to achieve the trade-off between transmission reliability, communication security, and energy efficiency, we develop a quantum-inspired marine predator algorithm (QMPA) for realizing rational configuration of system resources and prevent from eavesdropping. Simulation results demonstrate the superiority of the QMPA over other strategies. It is also indicated that proper IRS deployment and power allocation are beneficial for the enhancement of system overall capacity.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.1009-1011
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• 2011

With the growth of Smart Grid technologies, security and privacy will become the most important issues and more attention should be paid. There are some existing solutions about anonymization of smart meters, however, they still have some potential threats. In this paper, we describe an enhanced method to protect the privacy of consumer data. When metering data are required by a utility or the electrical energy distribution center for operational reasons, data are delivered not with the real IDs but with temporary IDs. In addition, these temporary IDs are changed randomly to prevent the attackers from analyzing the energy usage patterns. We also describe secure data transmission method for securing data delivered. In this way, we can enhance the privacy of Smart Grid System with low overhead.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.749-755
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• 2023

A new approximation method was proposed for treating the non-resonant spatial self-shielding effects of double heterogeneous region such as the double heterogeneous effect of VHTR fuel compact in the thermal energy range and that of BP compact with BISO. The method was developed based on the effective homogenization method and a spherical unit cell model with explicit coated layers and a matrix layer. The self-shielding factor was derived from the relation between the collision probabilities for a double heterogeneous compact and the effective cross section for the homogenized compact. First, the collision probabilities and transmission probabilities for all layers of the spherical model were calculated using conventional collision probability solver. Then, the effective cross section for the homogenized sphere cell representing the homogenized compact was obtained from the transmission probability calculated using the probability density function of a chord length. The verification calculations revealed that the proposed method can predict the self-shielding factor with a maximum error of 2.3% and the double heterogeneous effect with a maximum error of 200 pcm in the typical VHTR problems with various packing fractions and BP compact sizes.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.216-229
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• 2024

Pipeline steels for hydrogen transmission may cause hydrogen embrittlement due to absorption and diffusion of hydrogen through metals. Hydrogen pipes exhibited similar mechanical properties to atmospheric conditions in terms of tensile and yield strength in a hydrogen atmosphere. This paper aims to provide relevant information regarding hydrogen embrittlement in hydrogen transmission pipeline.