• The Journal of the Acoustical Society of Korea
• /
• v.16 no.3
• /
• pp.99-105
• /
• 1997

This paper analyzes DLL(Delay lock loop) under the multipath fading effects. The evaluated performance measures include the steady-state timing error probability density function (PDF) and the mean-time-to-lose-lock (MTLL) under multipath fading effects. The discriminator characteristic S(${\epsilon}$) is shown to be zero at the point of timing error ${\epsilon}_{0}$ that is not zero, and the MTLL decreases as the delayed signal power $g_{2}$ and delayed time ${\tau}_{d}$ increase. We approximate the steady-state timing error PDF linearly with these variables and evaluate the steady-state timing error PDF and MTLL. The severe multipath fading effects result lower MTLL, in this case we make MTLL larger by increasing the early-late discriminator offset ${\Delta}$. First, we calculate the timing error point ${\epsilon}_{0}$, and present the performance of DLL under multipath fading. The timing error PDF, MTLL and the performance of DLL with ${\Delta}$ are also investigated. And we conclude that the larger ${\Delta}$ makes a higher MTLL and a better performance of DLL under multipath fading effects.

• Journal of the Korean Society of Radiology
• /
• v.81 no.2
• /
• pp.379-394
• /
• 2020

Purpose To design a scoring system to predict malignancy of additional MRI-detected lesions in breast cancer patients. Materials and Methods Eighty-six lesions (64 benign and 22 malignant) detected on preoperative MRI of 68 breast cancer patients were retrospectively included. The clinico-radiologic features were correlated with the histopathologic results using the Student's t-test, Fisher's exact test, and logistic regression analysis. The scoring system was designed based on the significant predictive features of malignancy, and its diagnostic performance was compared with that of the Breast Imaging-Reporting and Data System (BI-RADS) category. Results Lesion size ≥ 8 mm (p < 0.001), location in the same quadrant as the primary cancer (p = 0.005), delayed plateau kinetics (p = 0.010), T2 isointense (p = 0.034) and hypointense (p = 0.024) signals, and irregular mass shape (p = 0.028) were associated with malignancy. In comparison with the BI-RADS category, the scoring system based on these features with suspicious non-mass internal enhancement increased the diagnostic performance (area under the receiver operating characteristic curve: 0.918 vs. 0.727) and detected three false-negative cases. With this scoring system, 22 second-look ultrasound examinations (22/66, 33.3%) could have been avoided. Conclusion The scoring system based on the lesion size, location relative to the primary cancer, delayed kinetic features, T2 signal intensity, mass shape, and non-mass internal enhancement can provide a more accurate approach to evaluate MRI-detected lesions in breast cancer patients.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.05a
• /
• pp.179-182
• /
• 2008

It needs to consider of turns during a path-finding on real road network. Because a car is delayed by waiting a traffic signal and decreasing speed when drived in a turn road such as cross road and slip road. If a straightness of a path is increased, a real cost of traveling should be able to decrease. An older method, the algorithm with Turn Heuristic, considered of this case. The algorithm, that differently gave weights to left, right and U-turns, improved a straightness of a path, but increased a cost of exploring. In this paper, we propose a improved Turn Heuristic Algorithm. Proposed algorithm uses Dynamic Turn Heuristic. It is able to more decrease a cost of exploring than older method by using the Turn Heuristic in a part of path-finding.

• Journal of Fisheries and Marine Sciences Education
• /
• v.12 no.2
• /
• pp.191-198
• /
• 2000

An experiment was carried out to obtain the fundamental data on the auditory thresholds of fishes for catching method using audible frequency sound, the auditory thresholds of dusky spinefoot Siganus fuscescens(Houttuyn) were measured in the presence of masking noise in the spectrum level range of 74 - 83dB re $1{\mu}Pa/{\sqrt{Hz}}$ by heartbeat conditioning technique using pure tones coupled with a delayed electric shock. The auditory critical ratios were about 23 - 34dB at measurement frequency range. The ratio increased almost linearly with increasing frequency from 200 to 500Hz. The noise spectrum level at the start of masking was about 61 - 73dB within the measurement frequency range. This suggests that hearing of dusky spinefoot is masked in the natural environment with the noise spectrum level above 70dB. The sound pressure level of which the signal sound of 100Hz is recognized by dusky spinefoot under the white noise of 70dB is above 98dB and the critical ratio of them is above 23dB.

• Journal of Trauma and Injury
• /
• v.28 no.3
• /
• pp.190-194
• /
• 2015

Blunt cerebrovascular injury is defined as a vertebral or carotid arterial structural wall injury resulting from nonpenetrating trauma. Complete traumatic internal carotid artery occlusion is very rare condition accounting for 0.08~0.4 0f all trauma patients and believed to be associated with the greatest risk of ischemic stroke reported in 50~90% in a few small series. A 55-year-male was admitted with drowsy mentality and severe headache after a fall down accident. Brain computed tomography showed a subdural hematoma at the both frontal area with a fracture of the occipital skull bone. Two days after admission, he suddenly complained with a right side hemiparesis of motor grade 2. Brain magnetic resonance diffusion demonstrated multiple high flow signal changes from the left frontal and parietal lesion. Computed tomographic angiogram (CTA) revealed absence of the left ICA flow. Trans femoral cerebral angiography (TFCA) showed complete occlusion of the left internal carotid artery (ICA) at ophthalmic segment in the left ICA angiogram and flows on the left whole hemispheric lesions through the anterior communicating artery in the right ICA angiogram. We decided to conduct close observations as a treatment for the patient because of acute subdural hematoma and sufficient contralateral cerebral flow by perfusion SPECT scan. Two weeks after the accident, he was treated with heparin anticoagulation within INR 2~4 ranges. He recovered as the motor grade 4 without another neurologic deficit after 3 months.

• The Journal of Internal Korean Medicine
• /
• v.26 no.3
• /
• pp.575-586
• /
• 2005

FC(free choresterol) plays an important role in normal and pathophysiological cells including that of messenger molecule or dilator of blood vessels in such illnesses as artheriosclerosis, hypertension and myocardial infarction. Smooth muscle and endothelial cell functions in the arteria wall are unified by complex intercellular signalling processes. In arteria comprised of one layer of smooth muscle cells surrounding the endothelium, the close apposition of the two cell types enables a signal derived from one cell to rapidly diffuse to neighboring cells. Experimentation was conducted to investigate the potential contribution of Sohaphyangwon(SHHW) on levels of FC generated by goaded microphages, and mechanisms of protection against ACAT inhibitor. It was found that J774 macrophages, which normally do not express FC were expressed by oxLDL and ACAT inhibitor. SHHW protected cells were found to be resistant to oxLDL and delayed death following the FC. Inhibition of FC formation abolished the protective effect against ACAT inhibitor exposure. Cadiovascular diseases include abnormalities of blood vessels dysfunction of the renin-angiotension system. What relation herbal medicine may have with vessel endothelium necrosis was here studied. In Oriental Medicine, SHHW water extract used for diseases in relation to cardiovascular systems. The resistence to cardiovascular disease of ACAT inhibitor induced J774 macrophage cells were studied through analysis of cell morphological patterns and immunochemistry of SHHW. The results of this study suggest that SHHW has protective effects on the cardiovascular system, and that it is effective in both prevention and treatment of diseases of the cardiovascular system, particularity against necrosis of blood.

• Journal of Intelligence and Information Systems
• /
• v.5 no.1
• /
• pp.103-123
• /
• 1999

Input filtering as a preprocessing method is so much crucial to get good performance in time series forecasting. There are a few preprocessing methods (i.e. ARMA outputs as time domain filters, and Fourier transform or wavelet transform as time-frequency domain filters) for handling time series. Specially, the time-frequency domain filters describe the fractal structure of financial markets better than the time domain filters due to theoretically additional frequency information. Therefore, we, first of all, try to describe and analyze specially some issues on the effectiveness of different filtering methods from viewpoint of the performance of a neural network based forecasting. And then we discuss about neural network model architecture issues, for example, what type of neural network learning architecture is selected for our time series forecasting, and what input size should be applied to a model. In this study an input selection problem is limited to a size selection of the lagged input variables. To solve this problem, we simulate on analyzing and comparing a few neural networks having different model architecture and also use an embedding dimension measure as chaotic time series analysis or nonlinear dynamic analysis to reduce the dimensionality (i.e. the size of time delayed input variables) of the models. Throughout our study, experiments for integration methods of joint time-frequency analysis and neural network techniques are applied to a case study of daily Korean won / U. S dollar exchange returns and finally we suggest an integration framework for future research from our experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.10
• /
• pp.2317-2323
• /
• 2010

When the muscle is contracted by continuous and same, the force takes fatigue and stiffness. The aim of this study was to know how the fatigue and muscle stiffness change during an isometric contraction. Surface Electro myography(EMG) signal monitoring system and ultrasonic transducer set up the same muscle stem, subjects contract his right femoris muscle by submaximal isometric contraction(50% of MVC) until exhaustion. Before and after the test, muscle stiffness was measured and EMG was measured during the contraction. As time goes by, muscle fatigue was increased. and the stiffness was shown strongly after the contraction. These results show if the muscle becomes more and more fatigued, the circulation of muscle is delayed although the contraction doesn't happen. So muscle stiffness is increased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.270-275
• /
• 2016

The characteristics of the fuel quantity, injection rate and macro spray development was investigated under a range of diesel fuel temperatures. The actual injection quantity decreased despite the same signal of the injection start and injection duration as the fuel temperature decreased. The injection rate measurements confirmed that the actual injection commencement was delayed and the actual injection duration was shortened under lower fuel temperature conditions, which explains why the injection quantity decreased. Spray tip penetration with a lower fuel temperature was longer than that with a higher fuel temperature due to the deteriorated atomization. As a pre-test for the combustion experiment under low temperature conditions, piston targeting with pilot injection was accomplished, which showed that the fuel droplet from pilot injection was introduced into the crevice area. This suggests that the pilot injection quantity and timing should be chosen with careful consideration for actual applications.

• Journal of Korea Multimedia Society
• /
• v.15 no.3
• /
• pp.299-311
• /
• 2012

Recently, H.264 SE(scalable extension) has become a standard of next generation multimedia service which is one source, multi-user service in the telecommunication environment of different kinds of networks and terminal equipments. But existing DRM schemes for multimedia service are not fit for H.264 SE system. Because the amount of transmitted multimedia data is changed considering network environment and terminal equipments' performance by the system, but in the existing DRM schemes, the amount of handled multimedia data are not variable according to network environment and terminal equipments' performance. In this paper, an information security scheme combined video watermarking and encryption is presented for H.264 SE. Amount of watermarks and embedding positions are calculated by the frame number of enhancement layers which are created according to the state of networks and terminal equipments. In order to minimize delayed time by video watermarking and encryption, the video data are watermarked and encrypted in the H.264 SE compression process. In the experimental results, we confirmed that proposed scheme is robust against video compression, general signal processing and geometric processing.