• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.6A
• /
• pp.685-692
• /
• 2008

In this paper, we propose a timing recovery loop for Inmarsat mini-m system downlink receiver. Inmarsat mini-m system requires a timing recovery loop which is robust in frequency offset and has fast acquisition because Inmarsat mini-m system specification requires frequency tolerance is required of ${\pm}924$ Hz (signal bandwidth: 2.4 kHz) and acquisition time of UW (Unique Word) signal duration (15ms).Therefore, we propose a timing recovery loop which is suitable for Inmarsat mini-m system. The proposed timing recovery loop adopted noncoherent UW detector and differential ELD which applied differential UW signal for stability and fast acquisition in frequency offset environment. Simulation results show that the proposed timing recovery loop has stable operation and fast acquisition in frequency offset environment for the system.

• Bulletin of the Korean Mathematical Society
• /
• v.52 no.2
• /
• pp.439-452
• /
• 2015

In this paper we introduce and study the new properties ($W_{\Pi}$), ($UW_{{\Pi}_a}$), ($UW_E$) and ($UW_{\Pi}$). The main goal of this paper is to study relationship between these new properties and other Weyl type theorems. Moreover, we reconsider several earlier results obtained respectively in [11], [18], [14], [1] and [13] for which we give stronger versions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.12
• /
• pp.1715-1720
• /
• 2016

In the upcoming 5-generation mobile communication system, various techniques for improving the power efficiency and spectral efficiency have been proposed. 5G mobile communication system also have been studied a lot of multi-carrier-based modulation techniques like the 4G mobile communication system. In this paper, we analyzed the conventional system structure of the Zero-tail DFT-s-OFDM and UW (Unique Word) -DFT-s-OFDM system based on DFT-s-OFDM system in these techniques. UW and zero are added and used each system, and CP is removed. the result of quality of systems for simulation, OOB(Out of Band) power of Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM use the less time resource as long as CP length, also both systems are reduced about 11dB than DFT-s-OFDM system. In these result, Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM system are more effective than DFT-s-OFDM system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.115-118
• /
• 2014

Underwater Wireless Communication System can be useful for research of quality of water, ocean resources exploration, analysis ocean environment and so on. However, there exist security threats including data loss, data forgery, and another variety of security threats, because of characteristics of water, various geographical factors, intended attack, etc. To solve these problem, in this paper, we propose a CCM-UW mode of operation modified form of CCM mode of operation, providing data confidentiality, integrity, origin authentication and anti-attack prevent, for the Underwater Wireless Communication System. By implementing CCM-UW in MACA protocol(Underwater Wireless Communication MAC Protocol) and measuring speed of communication, we confirm the applicability of the security and analyze the communication environment impact.

• Journal of Korean Society of Water and Wastewater
• /
• v.35 no.3
• /
• pp.227-235
• /
• 2021

This study examined the effect of ultraviolet (UV) application on bacterial disinfection in a commercialized humidifier using ultrasonic wave (UW). To accurately examine disinfection kinetics in tap-water condition, tap-water was sterilized using a filter, and then inoculated with pure cultures of E. coli and P. putida with known viable counts. The disinfection kinetic characteristics were experimentally compared when UV alone, UW alone, and UW+UV together were applied in disinfecting the added bacteria in the commercialized humidifier. When UV alone was applied, bacterial disinfection kinetics followed a first-order decay reaction, and showed an approximately 10-time weaker disinfection compared to the typical UV disinfection in water treatment or wastewater treatment. When UW alone was applied, bacterial disinfection kinetics followed a second-order decay reaction with a low disinfection rate constant of 0.0002 min^-1(CFU/mL)^-1. When UV and UW were applied together, however and interestingly, the disinfection rate constant (0.0211 min^-1(CFU/mL)^-1) was approximately 100 times increased than that for the UW alone case. These results revealed that the co-use of UV and UW can provide synergistic effect on bacterial disinfection in a tap-water condition in household humidifiers.

• Journal of Ocean Engineering and Technology
• /
• v.15 no.4
• /
• pp.73-79
• /
• 2001

Underwater wet bead-on-plate welds were experimentally performed on 11mm thick SS400 steel plate as base metal by using six different types of flux coated electrodes of 3.2mm diameter. Two kinds of different flux coated wet arc electrodes (UW-1, UW-2) were individually designed flux materials, three kinds of the electrodes (E4301, E4311, E4313) were terrestrial electrodes and the another one (TN20) was an imported underwater wet welding electrode. As results, the individually designed flux coated underwater electrode, UW-2 and TN20 had a good starting and the excellent arc stability compared with other electrodes. No significant difference of bead appearance could be detected, but the slag detachability of TN20 electrodes was relatively undesirable. By rapid cooling rate, the hardness value and the portion of martensite of HAZ were increased, but it was considerably maintain stable for TN20 and UW-2 electrodes. The individually designed flux coated electrode, UW-2 could be used in practice for underwater bead welds.

• Journal of Korea Multimedia Society
• /
• v.14 no.12
• /
• pp.1572-1582
• /
• 2011

The rapid growth of UnderWater Acoustic Sensor Networks (UW-ASNs) has led researchers to enhance underwater MAC protocols against limitations existing in underwater environment. We propose the customized robust real-time packet inspection mechanism with addressing the problem of the search for the data packet loss and network performance quality analysis in UW-ASNs, and describe our experiences using this approach. The goal of this work is to provide a framework to assess the network real-time performance quality. We propose a customized and adaptive mechanism to detect, monitor and analyze the data packets according to the MAC protocol standards in UW-ASNs. The packet analyzing method and software we propose is easy to implement, maintain, update and enhance. We take input stream as real data packets from sniffer node in capture mode and perform fully analysis. We were interested in developing software and hardware designed tool with the same capabilities which almost all terrestrial network packet sniffers have. Experimental results confirm that the best way to achieve maximum performance requires the most adaptive algorithm. In this paper, we present and offer the proposed packet analyzer, which can be effectively used for implementing underwater MAC protocols.

• Journal of radiological science and technology
• /
• v.9 no.1
• /
• pp.145-145
• /
• 1986

• Progress in Superconductivity and Cryogenics
• /
• v.25 no.4
• /
• pp.28-31
• /
• 2023

This study presents a comprehensive procedure for the low cycle fatigue test of ultrasonically welded (UW) coated conductor (CC) lap-joints. The entire process is examined in detail, from the robust fabrication of the UW REBCO CC joints to the reliability testing under a low number of repeated cycle fatigue conditions. A continuous I_c measurement system enables real-time monitoring of I_c variations throughout the fatigue tests. The study aims to provide a step-by-step procedure that involves joint fabrication, electromechanical property (EMP) tests under uniaxial tension for stress level determination, and subsequent low-cycle fatigue tests. The joints are fabricated using a hybrid method that combines UW with adding In-Sn soldering, achieving a flux-free hybrid welding approach (UW-HW flux-free). The selected conditions for the low cycle fatigue tests include a stress ratio of R=0.1 and a frequency of 0.02 Hz. The results reveal some insights into the fatigue behavior, irreversible changes, and cumulative damage in the CC joints.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.3
• /
• pp.9-17
• /
• 2000

In this paper we implement computer simulation system of 4FSK signal MODEM using Quadrature detector and analyze overall tranceiver system. We follow the FLEX wireless paging system standards and construct premodulation filter and data frame. We propose an efficient open loop symbol timing recovery algorithm which takes advantage of 128 bit length preamble pattern and also propose a 32 bit UW pattern which Is based on the optimal UW detection method, and excellent aperiodic autocorrelation characteristic. The BER simulation in the fading channel as well as AWGN is performed with BCH coding and Interleaving to the Quadrature detector system and it is shown that a high coding fain occurs in the fading channel rather than AWGN channel.