Jae-hoon Jeong

Time-Domain Analysis of a Lossy Nonuniform Transmission Line

An analytical solution of the coupled Telegraphers equations for the voltage and current on a homogeneous lossy transmission line is presented. The resulting expression is obtained in the form of an exact time-domain propagator operating on the line voltage and current. It is shown that an application of Simpsons rule yields a simple accurate numerical representation of the propagator that can be used to analyze both homogeneous and inhomogeneous transmission lines. Numerical dispersion in lossy media is examined proving that this method has no numerical dispersion.

Dual channel noise reduction method using phase difference-based spectral amplitude estimation

We present a dual-channel noise reduction method for small mobile devices. Our method incorporates phase difference between channels into the conventional MMSE spectral amplitude estimator. It is possible to suppress unwanted directional noise signals, whose incident direction is different from that of the target speech signal. Experimental results show that the proposed method outperformed conventional dual-channel noise reduction methods in SNR and PESQ evaluations in a noisy environment.

Adaptive noise power spectrum estimation for compact dual channel speech enhancement

We present a novel noise power estimation method based on smoothed spectral minima tracking and subtractive blocking matrix for dual-channel speech enhancement. By combining spectral characteristics of the noisy mixture signals with spatial null beam-forming, noise over- and under-estimation problem can be substantially mitigated. The proposed noise estimation tested on the real-life nonstationary noise conditions outperformed other single-channel noise estimation based on minima tracking and dual-channel phase error based enhancement algorithm.

Dominant speech enhancement based on SNR-adaptive soft mask filtering

In this paper, we present a SNR-adaptive soft mask filter for multi-channel noisy speech enhancement. Incorporating frame-by-frame spectral magnitude ratios into the time-frequency(T-F) mask filter framework, the adaptive filter can be designed robust to changing environments. Experimental results show that the proposed adaptive mask filter can effectively suppress non-stationary noise components even in a closely-spaced microphone pair. Moreover, the soft mask compressed with sigmoidal nonlinearity can reduce musical noises so that improved PESQ values are obtained.

Semi-blind disjoint non-negative matrix factorization for extracting target source from single channel noisy mixture

We present a semi-blind non-negative matrix factorization(NMF) approach to suppress interference noise signals from a single channel mixture signal. By enforcing a disjointness constraint into the NMF error criterion under the semi-blind denoising framework, it is possible to decompose the mixture spectrogram into target and noise components by minimizing overlaps in the time-frequency domain. Experimental results show that the proposed semi-blind disjoint NMF algorithm can significantly suppress non-stationary noise components in the noisy mixture.

On reducing of core dump file size

In this paper a solution to minimize the size of core dump in computing machinery with limited resources is proposed. The proposed technique describes how to reduce some sections in core dump and yet still keeps the ability to debug with this reduced information on embedded systems.

Study on design rule verification procedure of semiconductor memory devices by using design based metrology (DBM)

At the early stage of development of semiconductor memory devices, design rule should be defined for providing design guidelines to the design engineers. Those design rules are usually expressed in terms of minimum sizes of simple patterns which describe lithography and process limitations. However the real chip designs consist of a variety of complex patterns, so minimum size design rules of simple patterns are not enough for optimizing design layout. Therefore, design rules considering various design patterns are more advisable rather than simple minimum rules. But it is not easy to setup those design rules due to the difficulties of a large number of pattern verification. In our work, we evaluate design rule verification procedure by using Design Based Metrology (DBM) to overcome the difficulties of inspecting many type of patterns. We designed a large number of test patterns including various 1D and 2D design structure. And those patterns could be inspected at a fast speed with a design based metrology. From all the measurement data, the proper design rules successfully introduced and verified. Finally we found out the suggested procedure is a suitable method for verifying design rules.

Method for automatic detection of the reasons of unusual system behavior by evaluation of correlation between events in monitoring tool

This article describes the method related to simplifying detection of the problem reason in applications by using automatic analyzing of monitoring data on embedded system. Usually, dependencies in monitoring data are not obvious and usually it is very complicated to find the relationship between error symptom and the reason of the problem. The suggested method finds dependencies in system behavior automatically that gets the chance to detect hidden reasons of the problem in huge amount of monitoring data. In particular, the proposed method detects the unusual system behavior and tries to find the most probable reason of such behavior by using statistical data mining algorithms. It structures monitoring data by special way and most probable reason of the problem is colored by monitoring tool to help the developer to analyze the system behavior more comfortable and more precise. The experiments show that this method can detect a wide set of problems in system behavior that accelerates and improves the analysis of system behavior according to monitoring information.

System-wide analyzer of performance: Performance analysis of multi-core computing systems with limited resources

In this paper a new dynamic performance analyzer intended for uni- and multi-core computing systems with limited resources is presented and described. This analyzer is called SWAP (System-Wide Analyzer of performance). Initial version of SWAP tool, called as ELP1 (Embedded Linux Probe 1), was developed in Samsung Research Center (SRC) in 2006. This tool uses functional interface of Kprobes to provide the dynamic instrumentation of Linux kernel for ARM and MIPS architectures. ELP1 functionality allowed collecting raw data information (suc as register values, memory dump, etc) for any user predefined function of Linux kernel. Next revision of ELP1 tool, ELP2, was developed in SRC in 2007. ELP2 functionality allowed collecting traces from predefined functions in Linux kernel that contains general information of system characterization. Traces in ELP2 contained information from main Linux kernel functions such as arguments, return values and content of global kernel structures. ELP2 had pseudo-graphical interface on target that allows stand-alone monitoring of the system without any network connection. SWAP can monitor both kernel and application levels of the Linux system. Additional to ELP2 functionality, SWAP provides evaluation of the set of important system characteristics for main Linux subsystems (such as Memory Management, Process Management, File System and Network). Also SWAP has some automatic performance analysis features such as trace comparison, automatic bottleneck region localization, etc.

The role of prosodic boundaries in comprehension of Korean pseudo‐cleft sentences

A large prosodic boundary triggers, in general, a high attachment of an ambiguously attached phrase (e.g., Susie learned that Bill called // on Monday). The informative boundary hypothesis (IBH), however, claims that such an effect of a local prosodic boundary is neutralized by the presence of another boundary (e.g., Susie learned // that Bill called // on Monday). According to the IBH, it is not the absolute size of the later boundary (here, pre‐PP boundary) but its size relative to any earlier boundary before a constituent containing only the lower attachment site. Since the IBH implies nothing about the interpretation of an ambiguous phrase whose attachment sites appear later, the current study, as an extension of the IBH, investigates whether the effectiveness of a prosodic boundary can be determined by its size relative to a relevant subsequent boundary. The results showed that the interpretation of the sentence‐initial subject NP was affected by the absolute size of the post‐NP boundary, but the later boundary type had nothing to do with the interpretation. This provides further evidence that prosodic information is processed in an incremental fashion (left‐to‐right) and perceivers tend to impose prosodic structures as fast as possible.