• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1346-1353
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• 1999

We propose the MADF(multiplication free adaptive digital filter) algorithm and implement the fractionally spaced equalizer based on it. To evaluate the performance of proposed MADF algorithm, fractionally spaced equalizer(FSE) is used. Especially, we present that this method have the advantages for the condition having the low-frequency and slow speed

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.189-190
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• 2008

In this paper, we evaluate the bit error rate (BER) performance for uplink communication of WiBro system when smart antenna technology is employed. It is shown that, by exploiting beamforming technology, smart antenna-based WiBro system shows improved performance by more than 4 dB in SNR compared to single input single output (SISO) system under one-path Rayhleigh fading channel condition.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.706-711
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• 2003

A numerical method is presented for computing unsteady incompressible two-phase flows with immersed solids. The method is based on a level set technique for capturing the phase interface, which is modified to satisfy a contact angle condition at the solid-fluid interface as well as to achieve mass conservation during the whole calculation procedure. The modified level set method is applied for numerical simulation of bubble deformation in a micro channel with a cylindrical solid block and liquid jet from a micro nozzle.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.9
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• pp.1321-1326
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• 1990

In this paper, the eye-opening conditions are investigated for the minimum bandwidth digital transmission systems where the sinc functions is used as a basic pulse so that only the Nyquist bandwidth is required for the channel. In order for these systems to be tolerant to the timing jitter in the receiver, the eye pattern should be open horizontally. It is proved that an eye opening condition which has been understood only as a sufficiency becomes a necessity as well. As its result, having a spectral null at teh Nyquist frequency is shown to have the same meaning as eye opening.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.969-974
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• 2002

Recently, many studies are performed according to increased interests about factory or room acoustics. In this study, the inside and environmental noise conditions of Diesel-locomotive load test building were investigated by multi-channel noise measurement system. In addition to this, the mitigation effects of environmental noise from this test building were analyzed using commercial software.

• ETRI Journal
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• v.6 no.1
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• pp.10-14
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• 1984

A method for image data compression, Called condtional replenishment, using the interframe correlation of image signal hasbeen studied. In this study, only those picture elements between successive frames are transmitted instead of every picture element in each, frame. A real time test simulator that can demonstrate the functions of conditional replenishment coder with condition of noiseless channel has been realized, and the result shows that the transmitting pixels can be compressed to the 25% of original signal retaining good picture quality.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.85-88
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• 2002

Maintaining a proper level of cell lead, system throughput can be maximized by a transmission rate control over the uplink in DS/CDMA cellular system to support integrated services of real-time and delay-tolerant traffic. We find that the cell load-based rate control scheme can be further enhanced by taking the varying channel condition into account In conjunction with some fair scheduling algorithm. Our simulation results show that the proposed scheme outperforms the original cell load-based rate control with the round-robin sharing scheduling scheme.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.265-267
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• 2004

A blind separation problem in a multiple-input-multiple-output (MIMO) linear time-invariant (LTI) system with finite-alphabet inputs is considered. A discrete-time matrix equation model is used to describe the input-output relation of the system in order to make full use of the advantages of modern digital signal processing techniques. At first, ambiguity problem is investigated. Then, based on the results of the investigation, a new identifiability condition is proposed for the case of an input-data set which is widely used in digital communication. A probability bound such that an arbitrary input matrix satisfies the identifiability condition is derived. Finally, Monte-Carlo simulation is performed to demonstrate the validity of our suggestions.

• Journal of Korean Neurosurgical Society
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• v.40 no.3
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• pp.159-163
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• 2006

Objective : Unique Internal carotid artery angiographic findings have been found especially in very poor grade aneurysmal subarachnoid hemorrhage[SAH] patients before and during the endovascular coiling. The author investigates their patterns and classifies them into lour subtypes. Methods : Among Hunt&Hess grade IV, V SAH patients, the author could gather eight patients who showed abnormal intracranial circulation in cerebral catheter-based angiography. Results : The author introduces new term 'misery collaterals' first and has classified them into four types with the case illustrations. Type 1 is the worst condition defined as almost no intracranial circulation. Type 2 is the condition of little intracranial circulation with contrast filling just only at vessels of brain base, type 3 is of no or little cortical circulation with contrast filling at bilateral large vessels of brain base through circle of Willis channel and type 4 is of visible bilateral cortical circulation but delayed intracranial circulation time. The prognosis of these eight patients showed misery collaterals were disappointed. Conclusion : These finding can be used as the supportive information in deciding a management plan in poor grade SAH patients.

• 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