• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.20-26
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• 2019

In this paper, we propose measurement based numerical resistivity model for low energy exploding foil initiator (LEEFI) of electronic safety and arming device(ESAD). A resistivity model describes a behavior of variable resistance in LEEFI by firing current. The previous resistivity model was based on high energy detonator applications as explosive bridge wire and exploding foil initiator. Therefore, to estimate the voltage, current, and burst time of LEEFI, a resistivity model suitable for LEEFI is needed. For the modeling of resistivity of LEEFI, we propose a specific action based equation which represents a behavior of LEEFI when firing current is applied. To verify the proposed model, we analyze a firing current transmission path to obtain parasitic impedance. We experimentally verify that the proposed resistivity model offers precise estimation for the behavior of variable resistance in LEEFI.

• International Journal of Contents
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• v.2 no.4
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• pp.19-24
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• 2006

In this paper, the performance of pre-equalization technique which can be applicable for the B-WLL uplink is evaluated and compared to post-equalization technique under three kinds of rain attenuation channels such as rain, intermittent light rain and thundershower. The BER performance comparisons of two algorithms (LMS and RLS) are investigated in the context of channel models and the length of training sequence. From the simulation results, it is shown that the post-equalization outperforms only at quite good channel conditions such as AWGN, while the pre-equalization can guarantee better BER performance at every channel conditions, especially performance gain increases as the severity of channel increases. It is concluded that the pre-equalizer using LMS algorithm is preferable at delay-tolerant situation where the complexity of algorithm is not a strict factor, while one using RLS is suitable for fast burst transmission with a relatively short training sequence.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1811-1818
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• 2009

This paper is about the research to maintain and enhance the flow of data of the wireless traffic control. Various types of burst traffic that were found at TCP window flow control have been removed or mitigated using the two-way traffic control. Currently, TCP ACK Compression problem appears during the transmission of the wireless communication control channel because the queues are mostly located at the end system. Therefore, in this paper, the periodic bursty characterist of the source IP queue wilt be analyzed to predict the maximum value of queues. And then the prediction tool will be applied to wireless communication traffic control to handle symmetric traffic as to increase the throughput and improve the performance.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.1
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• pp.37-43
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• 2009

In this study, the physical properties of base paper for the manufacture of mulching mat for afforestation seedling were investigated. The base paper for mulching mat was prepared by stock conditions of PAE and AKD addition into the screened slurry of KOCC for the strengthening effects of wet tensile and burst strength. The optimum additions of PAE and AKD were considered at 2% and 0.5%, respectively. The accelerated aging by ISO 5630-1 and wet heat aging method under hot water for 2 kinds of commercial mulching and wet strength paper were compared with the base paper prepared for mulching mat manufacture. The accelerated aging test for the base paper prepared for mulching mat manufacture resulted in the same tendency of physical properties as two kinds of commercial products. However, the results of wet heat aging test under hot water indicated that the physical strength for base paper prepared was much higher than others. In addition, the opacity behavior for base paper prepared was enough effects to obstruct weeds growth by isolating transmission of sunlight.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.341-357
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• 2010

Forward Error Correction (FEC) techniques have been adopted to overcome packet losses and to improve the quality of video delivery. The efficiency of the FEC has been significantly compromised, however, due to the characteristics of the wireless channel such as burst packet loss, channel fluctuation and lack of Quality of Service (QoS) support. We propose herein an Adaptive Cross-layer FEC mechanism (ACFEC) to enhance the quality of video streaming over 802.11 WLANs. Under the conventional approaches, FEC functions are implemented on the application layer, and required feedback information to calculate redundancy rates. Our proposed ACFEC mechanism, however, leverages the functionalities of different network layers. The Automatic Repeat reQuest (ARQ) function on the Media Access Control (MAC) layer can detect packet losses. Through cooperation with the User Datagram Protocol (UDP), the redundancy rates are adaptively controlled based on the packet loss information. The experiment results demonstrate that the ACFEC mechanism is able to adaptively adjust and control the redundancy rates and, thereby, to overcome both of temporary and persistent channel fluctuations. Consequently, the proposed mechanism, under various network conditions, performs better in recovery than the conventional methods, while generating a much less volume of redundant traffic.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.183-186
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• 2004

본 논문에서는 수중 초음파 통신용 QPSK 버스트 수신기를 DSP시스템을 이용하여 구현하기위한 시스템 설계에 대하여 논한다. 본 논문에서 고려하는 시스템은 25kHz의 반송주파수를 사용하고, 심벌율은 5kHz이며, 데이터 전송율은 10,000bps이다. 송신기에서 심벌정보를 전송하기 위해 펄스성형필터를 거친 신호를 디지털 믹서기를 이용하여 디지털 영역에서 반송주파수 대역으로 신호를 변조한 후 200kHz로 샘플링하는 D/A변환기를 이용하여 전송 아날로그 신호를 생성한다. 수신기에서는 수신 신호를 디지털로 처리하기 위하여 100kHz로 free running하는 A/D 변환기를 이용하여 수신 데이터를 얻는다. 수신기에서는 32심벌 길이의 프리앰블을 이용하여 프레임 동기를 찾음과 동시에 개략적인 심벌시간 동기와 위상편이를 추정한다. 추정한 위상편이값은 2차 PLL (phase-looked loop)의 초기값으로 사용하여 위상 추적을 수행하는 전송 시스템이다. 또한, 된 논문에서는 실해역 전송 시험 테이터를 통하여 조류의 변화에 의해 발생하는 Doppler 편이를 보상하기 위하여 PLL이 필수적으로 필요함을 보인다.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1629-1635
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• 2016

A novel bacteriophage, PBES 02, infecting Cronobacter sakazakii was isolated and characterized. It has a spherical head of 90 nm in diameter and a tail of 130 nm in length, and belongs to Myoviridae as observed under a transmission electron microscope. The major virion protein appears to be 38 kilodaltons (kDa) in size. The latent period of PBES 02 is 30 min and the burst size is 250. Infectivity of the phage remained intact after exposure to temperatures ranging from 4℃ to 55℃ for 1 h. It was also stable after exposure to pHs ranging from 6 to 10 for 1 h. The phage effectively removed contaminating Cronobacter sakazakii from broth infant formula. PBES 02 has a double-stranded DNA genome of 149,732 bases. Its GC ratio is 50.7%. Sequence analysis revealed that PBES 02 has 299 open reading frames (ORFs) and 14 tRNA genes. Thirty-nine ORFs were annotated, including 24 related to replication and regulation functions, 10 related to structural proteins, and 5 related to DNA packaging. The genome of PBES 02 is closely related to that of two other C. sakazakii phages, CR3 and CR8. Comparison of DNA sequences of genes encoding the major capsid protein revealed a wide geographical distribution of related phages over Asia, Europe, and America.

• Geomechanics and Engineering
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• v.16 no.1
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• pp.85-95
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• 2018

Water affects the mechanical properties of coal and stress wave propagation. To comprehensively investigate the effect of water content on the properties of coal, laboratory tests including X-Ray Diffraction (XRD) analysis, P-wave test, S-wave test, static and dynamic compression test with different water contents were conducted. The compressive strength, elastic modulus and failure strain and their mechanism of coal specimen under coupled static-dynamic load with the increased water content were observed. Meanwhile, energy transmission and dissipation characteristics of a stress wave in coal specimens with different water contents under dynamic load and its relation with the failure features, such as fragmentation and fractal dimension, of coal was analyzed. Furthermore, the dynamic interpretation of water infusion to prevent coal burst based on water infusion model of coal seam roadway was provided.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.2
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• pp.20-26
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• 2009

The dominant incidents category for onshore and offshore natural gas transmission pipelines in the world is associated with outside forces. Incidents in the outside forces category embrace acts of nature, which typically cause widespread structural damage, as well as act of man, whose effects tend to cause dents and/or gouges localized at point of contact that are referred to as mechanical damage. Therefore, these damage types must be better addressed to avoid unnecessary and costly repairs and the possibility of catastrophic events. First of all, the characterizing features of mechanical damage in gas pipelines were evaluated by using of excavator or boring machine. There is no reliable method for evaluating the safe operating pressure of pipeline affected by mechanical damage. It is especially important to evaluate the remaining strength of damaged pipelines due to outside force. Therefore, the full scale burst tests were conducted to evaluate the remaining strength of pipe with mechanical damage that combines a dent and a gouge. This paper is supposed to provide information that will assist in developing a criterion to assess serviceability in pipelines with mechanical damage.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1946-1954
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• 2018

The aim of this study was to isolate and characterize a lytic Yersinia enterocolitica-specific phage (KFS-YE) as a biocontrol agent. KFS-YE was isolated and purified with the final concentration of ($11.72{\pm}0.03$) log PFU/ml from poultry. As observed by transmission electron microscopy, KFS-YE consisted of an icosahedral head and a contractile tail, and was classified in the Myoviridae family. KFS-YE showed excellent narrow specificity against Y. enterocolitica only. Its lytic activity was stable at wide ranges of pH (4-11) and temperature ($4-50^{\circ}C$). The latent period and burst size of KFS-YE were determined to be 45 min and 38 PFU/cell, respectively. KFS-YE showed relatively robust storage stability at -20, 4, and $22^{\circ}C$ for 40 weeks. KFS-YE demonstrated a bactericidal effect in vitro against Y. enterocolitica and provided excellent efficiency with a multiplicity of infection as low as 0.01. This study demonstrated the excellent specificity, stability, and efficacy of KFS-YE as a novel biocontrol agent. KFS-YE may be employed as a practical and promising biocontrol agent against Y. enterocolitica in food.