One of the most basic characteristics of the image is accompanied by its blur. It was 1962 that I had discovered for the first time in the world that the blur was a Gaussian type. In this paper the outline is described about historical details concerning this circumstances.

An optical FM system using an optical FM LD (laser diode) and an optical frequency discriminator (OFD), in which a nonlinear compensation scheme based on the interaction between its nonlinearities can minimize intermodulation distortion. This paper theoretically investigates the minimization influence for 3rd plus 5th order intermodulation distortion power for an optical FM radio-on-fiber system. The carrier to noise-plus-distortion power ratio (CNDR) is theoretically analyzed in employing the OFD whose transmission characteristic is controlled by a phase shifter. The results show that the designed receiver can achieve higher CNDR in the application of multicarrier transmission.

We present theoretical and experimental results for a microwave photonic oscillator (MPO) that provides a microwave signal and a modulated optical wave simultaneously. Among the different techniques currently in use for optically generating a microwave signal, we have chosen a ring configuration based on an electro-optical Mach-Zehnder modulator (EOM) driven by a 1.55 µm DFB laser diode. An accurate modelling of EOM and the contributions from all noise sources in the oscillation loop allows us to predict performances of our designated MPO in a very good agreement with the measured oscillation power (up to 22 dBm, depending on the DC bias voltage) and phase noise spectral density (-130 dBc/Hz @ 10 kHz away from the carrier). We propose this hybrid microwave photonic source to be used as a local oscillator for a coherent laser radar operating at 1550 nm. A good compromise between a very high tunability range (1-8 GHz) and a high spectral purity (> -120 dBc/Hz @ 10 kHz) is obtained through a dual-loop configuration for the MPO.

Recently, we have discovered wave propagation phenomena which are continuously existing waves of changing phase states between two adjacent oscillators from in-phase to anti-phase or from anti-phase to in-phase in van der Pol oscillators coupled by inductors as a ladder. We named the phenomena as "phase-inversion waves." In this study, phase-inversion waves which exist in the state of in-and-anti-phase synchronization have been found. We observe the phenomena by circuit experiments and computer calculations, and investigate them.

An effective transmitter power control method is indispensable in combating the near-far problem and minimizing the effect of interference on the system capacity. This paper investigates the power control problem for the uplink direct sequence-code division multiple access (DS-CDMA) system. In recent works on power control problem, power levels are assumed to take on any positive real value. However, in practical systems, power levels are discrete. This paper therefore proposes a power control algorithm over a discrete set of power levels in which each base station locally optimizes the power set of all users in its own cell. Also, we investigate its convergence and power consumption properties. Simulation results indicate that the proposed power control algorithm converges faster and provides an improved performance.

This paper proposes a real-time scheduling mechanism for web server that finds a way to solve so-called priority inversion problem between tasks handling real-time web requests with higher priorities and tasks with lower priorities like HTML requests. The priority inversion problem of web server stems from operating two independent schedulers, web scheduler and kernel scheduler, without exchanging scheduling information or considering the requirement of each other. In the proposed mechanism, two schedulers are integrated in a kernel and the integrated scheduler schedules real-time web tasks and other application tasks together based on their priorities. Since the unified scheduler sees all tasks simultaneously in system, it can schedule the tasks with their absolute priorities and reduce the execution delay caused by the priority inversion. The proposed mechanism provides web server with a better chance to efficiently serve real-time web requests. The feasibility and performance of the proposed mechanism are empirically shown on an embedded system.

The conservative mode and the greedy mode scheduling algorithms for OBS switch with shared buffer are presented and discussed. Their performance is evaluated by computer simulations, as well as that of the greedy mode with void-filling algorithm. Simulation results show that the conservative mode and the greedy mode have different characteristics under different input load. The greedy mode and the conservative mode are more applicable in a real system than that with void-filling, owing to their lower computational complexity and FIFO characteristic. Finally, a composite algorithm integrated by the conservative mode and the greedy mode is proposed, which is adapted to the input load with the help of an input load monitor. The simulation results reveal that it has favorable performance under different load.

The complexities of many previous scheduling algorithms for IRIS tasks are too high to apply them to practical systems handling many tasks. The high complexities stem from the fact that the algorithms perform scheduling on all tasks in a system, producing an optimal solution. As a way to reduce the complexity of scheduling, we propose a heuristic on-line scheduling algorithm that schedules the IRIS tasks only in a scheduling window, producing a sub-optimal solution. A scheduling window contains W important tasks determined by a selection policy. The performance of the proposed algorithm is verified by simulation.

Full-duplex transmission of 60.0 GHz and 59.6 GHz millimeter-wave (mm-wave) signals of 155.52-Mbit/s differential phase shift keying (DPSK) data, radio-on-fiber (ROF) signals over 25-km-long standard single-mode fibers (SMFs) is experimentally demonstrated for the first time using a single 2-RF-port electroabsorption transceiver (EAT). The simplification of base stations (BSs) is strongly required to realize cost-effective and high-reliability mm-wave wireless access. This single EAT detects a C-band ROF signal modulated by a mm-wave downlink signal and simultaneously modulates the L-band optical carrier by a mm-wave uplink signal. The BS mainly consists of the EAT, leading to a simple and low-cost BS. Optical pilot tones and optical bandpass filters are used for photonic downconversion and photonic upconversion, to convert frequencies between mm-wave signals and intermediate frequency (IF) signals in the optical domain. With the use of optical conversions, these signals have no significant fading problems. The simultaneous transmission of both up- and downlinks has been achieved with the BER of less than 10-9. Also the fading problems due to the fiber dispersion of photonic conversions are analyzed mathematically in this paper. The single-EAT BS will become a promising candidate for a ROF access system.

Computation of scale space images requires numerical integration of partial differential equations, which demands large computational costs especially in nonlinear cases. In this paper, we present a computational scheme for nonlinear scale spaces based on iterated filtering of original images. This scheme is found to be a special case of numerical integration with a particularly adapted integration steplength. We show the stability of the iteration with local windows and that with global ones and analyze the deformation of edge waveforms in the filtering. Computational costs are evaluated experimentally for both local and global windows and finally we apply the nonlinear multi-scale smoothing to contrast enhancement of images.

In the image recognition problem, it is very important how we represent the image. Considering this, we propose a new representational method of images based on the stability in scale-space. In our method, the image is segmented and represented as a hierarchical region graph in scale-space. The object is represented as feature graph, which is subgraph of region graph. In detail, the region graph is defined on the image with the relation of each segment hierarchically. And the feature graph is determined based on the "life-time" of the graph of the object in scale-space. This "life-time" means how long feature graph lives when the scale parameter is increased. We apply our method to the face detection problem, which is foundmental and difficult problem in face recognition. We determine the feature graph of the frontal human face statistical point of view. We also build the face detection system using this feature graph to show how our method works efficiently.

We demonstrate polarization-independent and highly-efficient optical fiber wavelength converters in a 10 Gb/s NRZ transmission system. They are based on synchronous phase or frequency modulations of the two orthogonally polarized pump lights, and can suppress not only the stimulated Brillouin scattering (SBS) but also the spread of the converted spectrum without modulating the signal light.

Discrete cosine transform (DCT) coding has been proven to be an efficient means of image compression coding. A lot of efforts have been made to improve the coding efficiency of DCT based coding. This paper presents an adaptive DCT coding based on geometrical edge representation. This scheme is designed to properly exploit the correlation between edge direction and distribution of DCT coefficients. Edges are extracted from original images first. Then, sub-optimal block-size and scanning order are determined at each block based on the extracted edges. In this way an adaptive DCT scheme taking account of local characteristics of image can be achieved. It is shown through the simulations that the proposed algorithm outperforms a conventional coding scheme in terms of coding efficiency by 10-15%.

A bi-directional and multi-channel wireless telemetry capsule, 11 mm in diameter, is presented that can transmit video images from inside the human body and receive a control signal from an external control unit. The proposed telemetry capsule includes transmitting and receiving antennas, a demodulator, decoder, four LEDs, and CMOS image sensor, along with their driving circuits. The receiver demodulates the received signal radiated from the external control unit. Next, the decoder receives the stream of control signals and interprets five of the binary digits as an address code. Thereafter, the remaining signal is interpreted as four bits of binary data. Consequently, the proposed telemetry module can demodulate external signals so as to control the behavior of the camera and four LEDs during the transmission of video images. The proposed telemetry capsule can simultaneously transmit a video signal and receive a control signal determining the behavior of the capsule itself. As a result, the total power consumption of the telemetry capsule can be reduced by turning off the camera power during dead time and separately controlling the LEDs for proper illumination of the intestine.

In this paper, we propose an efficient requantization method for transcoding of MPEG video. Transcoding is the process of converting a compressed video format to another different compressed video format. We propose an simple and efficient transcoding by requantization in which MPEG coded video at high bit-rate is converted into MPEG bitstream at lower bit-rate. To reduce a image quality degradation, we use HVS (Human Visual System). By using this effect, the part of image in high activity region is coarsely quantized without seriously degrading the image quality. Experimental results show that the proposed method can provide good performance.

A LiNbO3 piezoelectric actuator controls the Au-Au contact gap. The control accuracy of the actuator is within the sub-micron range. Contact voltage, contact current, displacement of electrodes and driving voltage of the actuator were continuously and synchronously recorded by an A/D converter and send to a computer. The measured oscillograph data for 1500 contact operation were processed by the computer. Factors of discharge and bridge phenomena were derived at a contact operation. The delay time between displacement and driving signal of the actuator increased when one side of electric contact were vibrated. The resonance was seen in the actuator, and the dependency to the current and the amplitude was seen.

A voltage-controlled ring oscillator with an RC delay as an additional delay to vary the oscillation frequency is proposed. The use of MOS resistors provides a wide range tuning ability from 40 Hz to 366 MHz. The proposed circuit also enables implementation of a low frequency voltage-controlled ring oscillator with relatively smaller devices than the conventional one.

Some electromechanical devices and systems produced using MEMS fabrication processes are detailed. Two precision measurement metrologies for inspecting electromechanical products are also described. As the trend of electromechanical devices has been towards smaller and smaller sizes possessing robust mechanisms and powerful functions, micro-electric-mechanical system (MEMS) devices are becoming more the choice for meeting such requirements. Three MEMS examples are discussed in detail in this paper: CMOS compatible sensors, RF/microwave components, and packaged and integrated passive devices. The design thinking of a new free-fall sensor, which is an accelerometer and possesses a surprisingly low frequency response and broad bandwidth, is mentioned. In addition, an AVID (dvanced ibrometer/nterferometer evice) system for measuring tiny displacement as well as a Morphinscope system that has the advantage of a confocal microscope combined with a photon tunneling microscope and both developed by NTU's MEMS/NEMS group, are discussed. The excellent sensing ability of the free-fall sensor and the accuracy resolution of the two measurement systems are proved by experimental verification.

Various optical fiber connectors have been developed during the 20 years since optical fiber communications systems were first put into practical use. As the domain of optical fiber communication systems expanded from trunk lines to subscriber lines and customer premises the main focus changed from performance improvement to miniaturization and cost reduction. This paper describes the technical background, recent trends in standard optical connectors, and recent issues related to photonic connection technologies.

This paper proposes an enhanced method for multiple description coding (MDC) using whitening transform. The MDC using correlating transform is an error resilient coding technique that explicitly adds correlation between two descriptions to enable the estimation of one set from the other when one set is dropped in channel. This paper proposes a method to overcome practical problems that decoder must know statistics of original image in the conventional correlating transform method. The MDC using whitening transform does not need additional statistical information to reconstruct a image because the coefficients whitening transformed have uni-variance statistics. Our experimental results show that the proposed method achieves a good trade-off between the coding efficiency and the reconstruction quality. We obtain that PSNR of image reconstructed from two descriptions is about 0.93 dB higher at the 1.0BPP and PSNR from only one description is about 1.88 dB higher than conventional method at the same rate of 'Lena' image.