• The Journal of the Acoustical Society of Korea
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• v.21 no.4
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• pp.361-373
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• 2002

In this paper, we propose a channel normalization method to improve the performance of CMS (cepstral mean subtraction) which is widely adopted to normalize a channel variation for speech and speaker recognition. CMS which estimates the channel effects by averaging long-term cepstrum has a weak point that the estimated channel is biased by the formants of voiced speech which include a useful speech information. The proposed Formant-broadened Cepstral Mean Subtraction (FBCMS) is based on the facts that the formants can be found easily in log spectrum which is transformed from the cepstrum by fourier transform and the formants correspond to the dominant poles of all-pole model which is usually modeled vocal tract. The FBCMS evaluates only poles to be broadened from the log spectrum without polynomial factorization and makes a formant-broadened cepstrum by broadening the bandwidths of formant poles. We can estimate the channel cepstrum effectively by averaging formant-broadened cepstral coefficients. We performed the experiments to compare FBCMS with CMS, PFCMS using 4 simulated telephone channels. In the experiment of channel estimation, we evaluated the distance cepstrum of real channel from the cepstrum of estimated channel and found that we were able to get the mean cepstrum closer to the channel cepstrum due to an softening the bias of mean cepstrum to speech. In the experiment of text-independent speaker identification, we showed the result that the proposed method was superior than the conventional CMS and comparable to the pole-filtered CMS. Consequently, we showed the proposed method was efficiently able to normalize the channel variation based on the conventional CMS.

• Journal of Korea Port Economic Association
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• v.28 no.3
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• pp.167-192
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• 2012

The purpose of the study aims to analyse the judgement criterion of arrived ship under voyage charterparty with the Merida Case. A ship is an arrived ship if she is in port and either able to proceed immediately to a berth or in such a position that she is at the immediate and effective disposition of the chaterparty. Identification of the specified destination-whether berth or port-impacts on the incidence of loss occasioned by delay in loading or discharging, when the delay is due to the place at which the vessel is obliged by the terms of the charterparty to load or discharge her cargo being occupied by other shipping. The Merida case is an appeal by the charterers from a final Arbitration award of two very experienced arbitrators, dated 20th April, 2009. The arbitrators held that a voyage charterparty, dated 5th February, 2007, of the vessel, The M/V Merida, entered into between charterers and the owners, was a port rather than a berth Charterparty. The Primary relevance of this distinction does to the allocation, as between owners and charterers, of the risk of delay caused by congestion at load and discharge ports. The question of law arising in this appeal is whether the arbitrators were right to conclude that the charterparty was a port and not a berth charterparty. The arbitrators additionary placed some reliance on a post-contractual e-mail from the agents, which suggested that charterers did not dispute the validity of the NOR-and, hence, that this was a port charterparty.

• Korean Journal of Plant Resources
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• v.25 no.4
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• pp.407-415
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• 2012

Pinus pumila, which occurs in the northeast Asia, is found limitedly in Daecheongbong area of Mt. Seorak in the South Korea. This population was chosen to study spatial pattern, genetic diversity and spatial genetic structure. There were 48 polymorphic and 30 monomorphic I-SSR markers. A total of 65 individuals which distributed in the study site (40 m ${\times}$ 70 m) showed weakly aggregate distribution (Aggregate Index = 0.871). A total of 40 genets were observed from 65 individuals through I-SSR genotype comparison. Proportion of distinguishable genotype (G/N), genotype diversity (D) and genotype evenness (E) were 61.5%, 0.977 and 0.909, respectively. In spite of the small number and the limited distribution, Shannon's diversity index (I = 0.567) was relatively high as compared with those of other plant species. Spatial autocorrelation using Tanimoto's distance showed that the genetic patch was established within 12 m. Based on Mantel tests, there was relatively low correlation between genetic distance and geographic distance. Therefore, it seems the P. pumila population was formed by many parent trees in early stage. For ex situ genetic conservation of P. pumila, the sampling strategy is efficient at least above 12 m between individual trees.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.231-238
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• 2007

This paper describes the availability of the forthcoming integrated GNSS(Global Navigation Positioning System) positioning that includes GPS(Global Positioning System), Galileo, and QZSS(Quasi-Zenith Satellites System). We built a signal propagation model that identifies direct, multipath, and diffraction signals, using the principles of specular reflection and ray tracing technique. The signal propagation model was combined with 3D GIS(three-dimensional geographic information system) in order to measure the satellite visibility and positioning error factors, such as the number of visible satellites, average elevation of visible satellites, optimized DOP(dilution of position) values, and the portion of multipath-producing satellites. Since Galileo and QZSS will not be fully operational until 2010, we used a simulation in comparing GPS and GNSS positioning for a $1km{\times}1km$ developed area in Shinjuku, Tokyo. To account for local terrain variation. we divided the target area into 40,000 $5m{\times}5m$ grid cells. The number of visible satellites and that of multipath-free satellites will be greatly increased in the integrated GNSS environment while the average elevation of visible satellites will be higher in the GPS positioning. Much decreased PDOP(position dilution of precision) values indicate the appropriate satellite/user geometry of the integrated GNSS; however, in dense urban areas, multipath mitigation will be more important than the satellite/user geometry. Thus, the efforts for applying current technologies of multipath mitigation to the future GNSS environment will be necessary.

• Journal of Navigation and Port Research
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• v.37 no.4
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• pp.391-400
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• 2013

Each country has recently established and operated so called Aids to Navigation(AtoN) AIS system collecting and transferring information on the sea state and AtoN's position. Korea has also decided to introduce the system and been establishing it. And it has already installed and operated this system in Incheon and Daesan. For the purpose of giving the national standards of AtoN AIS, this paper is to investigate the present states of AtoN AIS systems in the above two area and to suggest the improvement to the operation of AtoN AIS system. To make it, the paper deals with the international regulations of related AtoN AIS and the cases of foreign's AtoN AIS system installed and also investigates the operation states of the system, in five modules such as system management, system composition, information, function and cooperation. The followings are concluded; improving the inconsistency of system management, reducing operator's confusion caused by excessive display of AtoN AIS system, improving the problem of receiving unnecessary information, improving the functional problems caused by AIS communication inability and improving AtoN AIS information which is presently not used on board.

• The Journal of Engineering Geology
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• v.6 no.3
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• pp.137-153
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• 1996

The purpose of this study is to investigate the possibilities of identifying and detecting underground cavities using seismic waves recorded by the fixed and mobile stations. During 18 months of field work we recorded chemical explosions near the Bongdarn station. Seismic Stations were installed on the free surface and underground inside the Samba mine. The seismograms at the fixed(lorg-term) seismic station show abrupt change of polarization characteristics which can he associated with the appearance of P-to-S converted phase(PS) at 150 ~ 200 msec after the first P arrival. This result indicates that converted phases are generated very near to the Bongdarn station at a depth of 190m. Shear-wave splitting phenomena have also been observeci The time delay between fast shear(fS) and slow shear(sS) waves ranges between 30 and 60 msec(average is 42 msec). However, exact time delay between the fast and the slow shear waves can not be accurately measured because of the very short time delay and limitation of sampling rate. Chemical explosion experiments were recorded at stations along various paths to contrast the seismic response of areas with and without cavities. The seismograms recorded at the stations installed at cavity areas show an abrupt change of polarization characteristics but not on the other stations. Seismic waves propagating through the cavity are characterized by the attenuation of high frequency waves and predominantly low frequency seismic waves after the S wave arrivals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.64-71
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• 2017

A damage estimation method is presented for jacket-type support structure of offshore wind turbine using a change of modal properties due to damage and committee of neural networks for effective structural health monitoring. For more practical monitoring, it is necessary to monitor the critical and prospective damaged members with a limited number of measurement locations. That is, many data channels and sensors are needed to identify all the members appropriately because the jacket-type support structure has many members. This is inappropriate considering economical and practical health monitoring. Therefore, intensive damage estimation for the critical members using a limited number of the measurement locations is carried out in this study. An analytical model for a jacket-type support structure which can be applied for a 5 MW offshore wind turbine is established, and a training pattern is generated using the numerical simulations. Twenty damage cases are estimated using the proposed method. The identified damage locations and severities agree reasonably well with the exact values and the accuracy of the estimation can be improved by applying the committee of neural networks. A verification experiment is carried out, and the damage arising in 3 damage cases is reasonably identified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.26-35
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• 2003

For the recognizing system to be classified the same or different images in the nature the rotation, scale and transition invariant features is to be necessary. There are many investigations to get the feature for the recognition system and the log-polar transform which is to be get the invariant feature for the scale and rotation is used. In this paper, we suggested the character recognition methods which are used the centroid method and the log-polar transform with the interpolation to get invariant features for the character recognition system and obtained the results of the above 50% differential ratio for the character features. And we obtained the about 90% recognition ratio from the suggested character recognition system using the BPEJTC which is used the invariant feature from the Mellin transform method for the reference image. and can be recognized the scaled and rotated input character. Therefore, we suggested the image character recognition system using the Mellin transform method and the BPEJTC is possible to recognize with the invariant feature for rotation scale and transition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.414-421
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• 2015

This paper presents a new method to decompose a duplicated ECG signal, which is measured from two people, to two individual ECG signals. In paper, it is shown that the duplicated ECG signal can be decomposed, provided that their SAECG signals are known. As the SAECG signal is the average of a ECG signal, it is a feature to identify individual ECG signals from the duplicated signal. Since the ECG signal is nearly periodic, so-called heart-rate, the period of each ECG signal can be found by using the autocorrelation of the duplicated signal, That is, the autocorrelation has high peaks at the multiple instants of heart-rate of each person. With the heart-rate of each person obtained by some processing, all R-peaks are identified by the SAECG signals. To be concrete, the SAECG signal of each person is repeatedly placed at the R-peak instants with his heart-rate, and the weight of each SAECG signal is computed by LMSE optimization. Finally, as adding the error signal in the LMSE optimization processing to the weighted SAECG signal, each individual ECG signal is obtained. In experimental results, we demonstrate that the duplicated ECG signal is successfully decomposed into two ECG signals.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.227-236
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• 2003

Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, acoustic emission (AE) sensors and accelermeters are used to detect leak locations which could provide all easier and move efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120m-long pipeline system for experiment is installed and the results with the system show that the algorithm with the AE sensors and accelerometers offers accurate pinpointing of leaks. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.