Abstract: Provided is a method of measuring a phase noise of a repetition rate of a femtosecond laser including generating a combined signal using a first wavelength element and a second wavelength element of an optical pulse train generated by the femtosecond laser, which is mode-locked, guiding the combined signal to a first path and a second path, allowing a signal of the second path to interfere with the signal of the first path, and outputting an interfering combined signal, dividing the interfering combined signal into a first interference signal and a second interference signal, converting the interference signals to radio frequency signals, and detecting a baseband signal including a frequency noise of the repetition rate from the radio frequency signals using a mixer.

Abstract: A magnetic resonance imaging apparatus and a diffusion-weighted image acquiring method form a radial k-space through a radial sampling and acquire a diffusion-weighted image from the radial k-space, with the diffusion-weighted image acquiring including receiving an echo signal generated from the subject, and forming a k-space having a plurality of sampling lines by sampling the echo signal that is received, wherein the directions of the diffusion gradient magnetic fields applied at the time of forming the sampling lines that compose the k-space to cross each other at two adjacent sampling lines.

Abstract: The present invention relates to an image processing system for enhancing the image quality of an ultrasound image.

Abstract: Disclosed is a method for fabrication of porous carbon fibers. More particularly, the method for fabrication of porous carbon fibers comprises the steps of: processing starch to prepare a gelled starch solution; adding organic acid to the gelled starch solution to prepare a starch solution; dissolving carbon nanotubes in a solvent and adding fiber formable polymer thereto to prepare a carbon nanotube/fiber formable polymer solution; mixing the starch solution with the carbon nanotube/fiber formable polymer solution obtained from the above steps, in order to prepare a carbon nanotube/starch/fiber formable polymer solution; electro-spinning or wet-state spinning the prepared carbon nanotube/starch/fiber formable polymer solution to produce starch composite fibers; oxidation heating the starch composite fibers, then, executing carbonization and vacuum heat treatment of the heated fibers, so as to fabricate the porous carbon fibers.

Abstract: Disclosed is an apparatus for monitoring an optical signal-to-noise ratio in a WDM optical network. The apparatus includes an orthogonal polarization component module for receiving an optical signal and outputting it after removing a signal component thereof at a specific frequency band; and calculation means for measuring both average signal and noise component intensity of the optical signal outputted from the orthogonal polarization component module. By removing a signal component at a specific frequency bandwidth and passing only a noise component through, it is possible to easily measure the noise intensity within a signal bandwidth that cannot be measured in general. A frequency band is set within a signal bandwidth, and the signal intensity is minimized at the set frequency band, so that it is possible to measure the optical signal-to-noise ratio even for a signal whose amplified spontaneous emission noise spectrum is not flat, irrespective of the signal pattern length.

Abstract: A high density magnetic recording medium which has coercivity suitable to a magnetic record, fine grains, and a uniform grain size distribution, and which includes a FePtC alloy thin film containing an optimum carbon content, and a method of manufacturing the high density magnetic recording medium. The magnetic recording medium includes the FePtC alloy thin film containing 25 volume % carbon, thus having microscopic magnetic and structural properties suitable to the high density magnetic recording medium.

Abstract: An add-drop wavelength filter is described which separates specific wavelength components from optical signals propagating through an optical waveguide or adds specific wavelength components thereto. In general, add-drop wavelength filters serve to separate or add specific channels in channels comprising several different wavelengths in a wavelength division optical communication system, and require good wavelength selectivity, stability and etc. Up to now, several types of add-drop wavelength filters are proposed, however disadvantageously they were not stable or were difficult to fabricate. The add-drop wavelength filter of the present invention comprising a mode discrimination coupler, Bragg gratings in which mode conversion occurs and etc., utilizes mode conversion in a dual mode waveguide and has low loss and stability.