• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.673-676
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• 1998

Future land remote sensing satellite systems will kikely be constrained in terms of communication band-width. To alleviate this limitation, the data must be compressed. Image data obtained from satellite exhibit a high degree of spatial and spectral correlations that must be properly exploited. In this paper we propose multispectral image data compression using wavelet transform and selective predicted vector quantization. Th eproposed method is based on accuratly predicting other band from reference band and reducing bit rate through threshold map. we can achieve better compression effeciency than conventional methods.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.92-98
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• 1998

The transform limited optical short pulses are generated by compression of pulses from a gain switched distributed feedback laser at 5 GHz repetition rate. The gain-switched pulses have the minimum pulse width of 27 psec with the spectral width of 1.1 nm. Thus the output pulses have a large amount of linear chirp and nonlinear chirp. We suppress the nonlinear chirp by passing the pulses through the optical band pass filter with 3 dB band width of 0.55 nm which is narrower than spectral width of the input pulses and generate 7.1 psec pulses by compressing the output with the dispersion compensating fiber. The pulses have time-bandwidth product of 0.49 which is close to the transform limited gaussian pulse. These pulses can be utilized as optical sources in 40 Gbit/s time division multiplexed optical transmission system.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.12-21
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• 2000

In this paper, we propose a novel hearing aid algorithm for sensorinural hearing loss restoration with multi-channel(band) dynamic range compression and psychoacoustics. In this way, we can present a normal perception condition to the impaired listener. The proposed algorithm make loudness scaling function achieve proper loudness level, and analysis masking property for the signal will be perceived to impaired listener, and then, restore normal spectral contrast using SMR(signal-to-masking ratio) defined by distance between the level of each frequency and masking threshold.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.601-603
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• 2004

Multi-Spectral Camera(MSC) is a payload on the KOMPSAT -2 satellite to perform the earth remote sensing. The instrument images the earth using a push-broom motion with a swath width of 15 km and a ground sample distance (GSD) of 1 m over the entire field of view (FOV) at altitude 685 Km. The instrument is designed to have an on-orbit operation duty cycle of $20\%$ over the mission lifetime of 3 years with the functions of programmable gain! offset and onboard image data compression/storage. MSC instrument has one(1) channel for panchromatic Imaging and four(4) channel for multi-spectral Imaging covering the spectral range from 450nm to 900nm using TDI CCD Focal Plane Array (FPA). In this paper, the configuration, the interface of MSC hardware and the MSC operation concept are described. And the method of the MSC calibration are described and the design of MSC calibration operation to measure the change of MSC after Launch & Early Operation(LEOP) and normal mission operations are discussed and analyzed.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3
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• pp.315-322
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• 2002

In this paper, a new temporal decomposition method is proposed. which takes into consideration not only spectral distortion but also bit rates. The interpolation functions, which are one of necessary parameters for temporal decomposition, are obtained from the training speech corpus. Since the interval between the two targets uniquely defines the interpolation function, the interpolation can be represented without additional information. The locations of the targets are determined by minimizing the bit rates while the maximum spectral distortion maintains below a given threshold. The proposed method has been applied to compressing the LSP coefficients which are widely used as a spectral parameter. The results of the simulation show that an average spectral distortion of about 1.4 dB can be achieved at an average bit rate of about 8 bits/Frame.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.825-827
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• 2003

Multi-Spectral Camera(MSC) is a payload on the KOMPSAT-2 satellite to perform the earth remote sensing. The instrument images the earth using a push-broom motion with a swath width of 15 km and a ground sample distance (GSD) of 1 m over the entire field of view (FOV) at altitude 685 Km. The instrument is designed to have an on-orbit operation duty cycle of 20% over the mission lifetime of 3 years with the functions of programmable gain/ offset and on-board image data compression/storage. The MSC instrument has one(1) channel for panchromatic imaging and four(4) channel for multi-spectral imaging covering the spectral range from 450nm to 900nm using TDI CCD Focal Plane Array (FPA). In this paper, the architecture and function of MSC hardware including electrical interface and the operation concept which have been established based on the mission requirements are described. And the design and the preparation of MSC system operation are analyzed and discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3543-3557
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• 2017

Compression is a very important technique for remotely sensed hyperspectral images. The lossless compression based on the recursive least square (RLS), which eliminates hyperspectral images' redundancy using both spatial and spectral correlations, is an extremely powerful tool for this purpose, but the relatively high computational complexity limits its application to time-critical scenarios. In order to improve the computational efficiency of the algorithm, we optimize its serial version and develop a new parallel implementation on graphics processing units (GPUs). Namely, an optimized recursive least square based on optimal number of prediction bands is introduced firstly. Then we use this approach as a case study to illustrate the advantages and potential challenges of applying GPU parallel optimization principles to the considered problem. The proposed parallel method properly exploits the low-level architecture of GPUs and has been carried out using the compute unified device architecture (CUDA). The GPU parallel implementation is compared with the serial implementation on CPU. Experimental results indicate remarkable acceleration factors and real-time performance, while retaining exactly the same bit rate with regard to the serial version of the compressor.

• The Journal of the Acoustical Society of Korea
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• v.31 no.5
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• pp.273-279
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• 2012

In this thesis, a nonlinear compression fitting method was studied for each frequency channel of a 64 channel digital hearing aid. Unlike conventional fitting formula method done from the result of the hearing loss test, the present fitting method uses the auditory threshold of sound pressure measured near the tympanic membrane while ITE (In-The-Ear) hearing aid is fitted into the user's ear canal. Also, the spectral distribution of the voice sound pressure was used for realizing of output sound pressure compression curves against input sound pressure level. Theoretical research results of FFT-iFFT compression algorithm has been evaluated by experimental gain measurements at each different input sound pressure level 50 dB, 70 dB, 90 dB respectively.

• ETRI Journal
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• v.27 no.3
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• pp.330-333
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• 2005

The Inter-Channel Level Difference (ICLD) is a cue parameter to estimate spectral information in a binaural cue coding that has been recently in the spotlight as a multichannel audio signal compression technique. Even though the ICLD is an essential parameter, it is generally distorted by quantization. In this paper, a new modified ICLE representation method to minimize the quantization distortion is proposed by adopting a flexible determination of the reference channel and the unidirectional quantization. Our experimental result confirms that the proposed method improves the multichannel audio output quality even with the reduced bit-rate.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.432-435
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• 2004

MSC (Multi Spectral Camera) system is a remote sensing payload to obtain high resolution ground image. In this application, uniformity characteristic is important as well as GSD (Ground Resolved Distance) and SNR (Signal to Noise Ratio). MSC image chain is consisted of OM (Optical Module), CCD, Video processor, NUC and DCSU (Data Compression and Storage Unit). Each block makes and corrects MSC's nonuniformity response. This paper shows the cause of nonuniformity error and the correction scheme of MSC system from the electronic point of view.