• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.137-146
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• 2002

In order to remove the intersymbol interference(ISI) phenomenon in data transmission channel, the structure and convergence analysis of the improved multiplication free adaptive digital filter(IMADF) is presented. Under conditions of zero-mean, wide-sense stationary and white Gaussian noise, it is shown that this paper analyze the convergence characteristics of the IMADF with a fractionally-spaced equalizer(FSE). In the experimental results, the convergence characteristics of the IMADF algorithm is almost same as the sign algorithm, but is better than the MADF algorithm. Here, this algorithm has useful characteristics when the correlation of the input signal is highly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1329-1334
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• 2001

This paper deals with the application of a sound-ray method to the analysis of the sound field in an ultrasonic cleaner. In order to include the wave interference phenomenon, the method has been modified to consider the phase of sound rays, The improved algorithm has been implemented by developing a Visual C＋＋ program, The algorithm has been verified by comparing the analysis results of BEM reported earlier. It has been shown that the algorithm can be used to calculate ultrasonic fields in a cleaning- container with an object to be cleaned.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.441-451
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• 2019

When a store is launched, the umbilical plug should be separated from the launcher without any physical interference and fragments. In order to satisfy these conditions, an umbilical plug and an umbilical separating device were designed. The plug is separated from the receptacle of the store while moving along inclined planes by the store thrust and the spring force connected from the launcher to the plug. As a result of the prototype test, the hanger on the store collided with the plug. Several tests were conducted after some actions were taken to prevent the collision. However, not only the same phenomenon was repeated, but also fragmentation occurred. In this study, the non-colliding conditions were analyzed through rigid and flexible multi-body dynamics analysis.

• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.156-159
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• 1996

Element failure occurs with high probability for every array used in the real world ; that is, it is a common phenomenon that there are one or more elements with no output. Element failure produces an elevated sidelobe level and fails to reject the interference signals in an adaptive beamformer. In this paper, we present the adaptive beamforming algorithm for array with element failure. The presented method minimizes the array output power subject to a set of linear constraints which maintain the frequency response in the look direction and force the weights of the inoperative elements to zero. Numerical results have been included.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1291-1293
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• 2007

Due to dense deployment and innumerable amount of traffic flow in wireless sensor networks (WSNs), congestion becomes more common phenomenon from simple periodic traffic to unpredictable bursts of messages triggered by external events. Even for simple network topology and periodic traffic, congestion is a likely event due to dynamically time varying wireless channel condition and contention caused due to interference by concurrent transmissions. In this paper, we have proposed three mechanisms: upstream source count and buffer based rate control and snoop based MAC level ACK scheme to avoid congestion. The simulation results show that our proposed mechanism achieves around 80% delivery ratio even under bursty traffic condition

• Applied Microscopy
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• v.51
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• pp.7.1-7.9
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• 2021

Neuromorphic systems require integrated structures with high-density memory and selector devices to avoid interference and recognition errors between neighboring memory cells. To improve the performance of a selector device, it is important to understand the characteristics of the switching process. As changes by switching cycle occur at local nanoscale areas, a high-resolution analysis method is needed to investigate this phenomenon. Atomic force microscopy (AFM) is used to analyze the local changes because it offers nanoscale detection with high-resolution capabilities. This review introduces various types of AFM such as conductive AFM (C-AFM), electrostatic force microscopy (EFM), and Kelvin probe force microscopy (KPFM) to study switching behaviors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2381-2391
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• 2013

In general, ground's thermal properties, types of heat exchanger, operational method, thermal interference between piles can be considered as key factors which affect the thermal performance of energy pile. This study focused on the effect of these factors on the performance by a numerical model reflecting a real ground condition. Depending on the degree of saturation of ground, pile's heat transfer rate showed a maximum difference of three times, and the thermal resistance of pile made a maximum difference of 8.7%. As for the type of heat exchanger effects on thermal performance, thermal efficiency of 3U type energy pile had a higher value than those of W and U types. The periodic operation (8 hours operation, 16 hours pause) can preserve about 20% of heat efficiency compared to continuous operation, and hence it has an advantage of preventing the thermal accumulation phenomenon. Thermal interference effect in group piles may vary depending on the ground condition because the extent decreases as the ground condition varies from saturated to dry. The optimal separation distance that maintains the decreasing rate of heat efficiency less than 1% was suggested as 3.2D in U type, 3.6D in W type, and 3.7D in 3U type in a general ground condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1631-1636
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• 2015

With the advance of wireless communication technology in terrestrial area, underwater communication is also evolving very fast from a simple point-to-point transmission to an elaborate networked communications. Underwater acoustic channel has quite different features comparing with the terrestrial radio channel in terms of propagation delay, Doppler shift, multipath, and path loss. Thus, existing technologies developed for terrestrial communication might not work properly in underwater channel. Especially medium access control (MAC) protocols which highly depend on propagation phenomenon should be newly designed for underwater network. CSMA/CA has drawn lots of attention as a candidate of underwater MAC protocol, since it is able to resolve a packet collision and the hidden node problem. However, a received signal could be degraded by the interferences from the nodes locating outside the receiver's propagation radius. In this paper, we study the effects of interference on the CSMA/CA based underwater network. We derived the SNR with the interference using the sonar equation and analyzed the degradation of the RTS/CTS effects. These results are compared with the terrestrial results to understand the differences. Finally we summarized the design considerations in CSMA/CA based underwater network.

• Journal of Oral Medicine and Pain
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• v.34 no.2
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• pp.217-225
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• 2009

As Pain is a comprehensive, biopsy chosocial phenomenon, improved understanding and successful management of pain need assessment of health-related quality of life and psychological states. The purpose of this study was to evaluate pain severity and pain-related interference to daily lives for patients with non-dental, orofacial pain(OFP) and a possible relation of OFP with psychological morbidity. Relation with such factors as gender, age, pain duration and diagnosis was also assessed. Inclusion criteria was all new patients with non-dental OFP attending the oral medicine.orofacial pain clinic of Dankook University Dental Hospital over 3 months' period, who completed the questionnaires of the Brief Pain Inventory (BPI) and Hospital Anxiety and Depression Scale (HADS). Prior to the first consultation, the patients were asked to fill out the questionnaire in the waiting room and were diagnosed through consultation and clinical examination. Total subjects were 163 with M:F ratio of 1:1.5 and mean age of 34.6${\pm}$17.7 years. Mean duration of pain was 13.3${\pm}$26.2 months and all patients were divided into; Trigeminal Neuralgia group (TN, N=8), Neuropathic Pain group (NeP, N=9), Persistent Idiopathic Facial Pain group (PIFP, N=8), and Temporomandibular Disorders group (TMD, N=138), subdivided into muscle problem (TMD-m, N=73), joint problem (TMD-j, N=24) and muscle-joint combined problem (TMD-c, N=41). OFP patients showed moderate pain severity and moderate pain-related interference. There was no gender difference in overall pain severity and interference and levels of anxiety and depression. Elderly patients aged ${\geq}$ 60 years showed higher pain severity (p<0.05). Patients with chronic pain ${\geq}$ 3 months reported more increased level of anxiety and depression than those with acute pain (p<0.05). Compared to TMD patients, patients with TN, NeP and PIFP suffered from higher level of pain and pain-related interference and reported higher level of anxiety and depression (p<0.05). Pain interference was closely correlated with their pain severity and with psychometric properties such as anxiety and depression. Pain severity was weakly correlated with levels of anxiety and depression. The results suggest a need for psychosocial assessment and support for successful management of OFP in addition to control of pain itself.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.351-356
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• 2012

Ultrasonic cavitation is a physical phenomenon that generates and collapses microbubbles in media (mainly fluids) under conditions of strong ultrasonic irradiation. In this study, changes in the ultrasonic acoustic characteristics of bubble clouds in relation to ultrasonic irradiation were observed by the quantitative evaluation of cavitation yields. Concave-type single ultrasonic transducers with center frequencies of 500 kHz and 1.1 MHz were used to produce cavitation, and 2.25 MHz interference ultrasonic waves that would traverse any bubble clouds generated were used to analyze the cavitation. The parameters used for the evaluation of cavitation yields (changes in the center frequency, attenuation characteristics, and the propagation time of penetrating waves) were analyzed in relation to the cavitation-generating conditions (irradiation intensity, excitation signal, and center frequency). On the basis of these results, correlations between the changes in the center frequency and irradiation intensity were identified. Although the correlation coefficient was low, notable changes were observed in the center frequency under certain irradiation conditions. Attenuation trends in the interference ultrasonic waves showed high correlations with all the irradiation conditions, and it was noted that these trends were not affected by the forms of cavitation generated. No differences in the propagation time were observed among different irradiation conditions. These findings suggest that bubble yields can be quantitatively evaluated effectively by evaluating the diverse irradiation conditions and that such a quantitative evaluation could be used to study the basic cavitation phenomenon occurring in high-intensity ultrasonic wave treatment.