Patents by Inventor Sang H. Choi
Sang H. Choi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8174695Abstract: A spectrometer system includes an array of micro-zone plates (MZP) each having coaxially-aligned ring gratings, a sample plate for supporting and illuminating a sample, and an array of photon detectors for measuring a spectral characteristic of the predetermined wavelength. The sample plate emits an evanescent wave in response to incident light, which excites molecules of the sample to thereby cause an emission of secondary photons. A method of detecting the intensity of a selected wavelength of incident light includes directing the incident light onto an array of MZP, diffracting a selected wavelength of the incident light onto a target focal point using the array of MZP, and detecting the intensity of the selected portion using an array of photon detectors. An electro-optic layer positioned adjacent to the array of MZP may be excited via an applied voltage to select the wavelength of the incident light.Type: GrantFiled: July 23, 2009Date of Patent: May 8, 2012Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Sang H. Choi, Yeonjoon Park, Glen C. King, James R. Elliott
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Patent number: 8094306Abstract: A spectrometer includes a micro-ring grating device having coaxially-aligned ring gratings for diffracting incident light onto a target focal point, a detection device for detecting light intensity, one or more actuators, and an adjustable aperture device defining a circular aperture. The aperture circumscribes a target focal point, and directs a light to the detection device. The aperture device is selectively adjustable using the actuators to select a portion of a frequency band for transmission to the detection device. A method of detecting intensity of a selected band of incident light includes directing incident light onto coaxially-aligned ring gratings of a micro-ring grating device, and diffracting the selected band onto a target focal point using the ring gratings. The method includes using an actuator to adjust an aperture device and pass a selected portion of the frequency band to a detection device for measuring the intensity of the selected portion.Type: GrantFiled: June 19, 2009Date of Patent: January 10, 2012Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Yeonjoon Park, Glen C. King, James R. Elliott, Sang H. Choi
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Patent number: 8089677Abstract: A dynamic optical grating device and associated method for modulating light is provided that is capable of controlling the spectral properties and propagation of light without moving mechanical components by the use of a dynamic electric and/or magnetic field. By changing the electric field and/or magnetic field, the index of refraction, the extinction coefficient, the transmittivity, and the reflectivity of the optical grating device may be controlled in order to control the spectral properties of the light reflected or transmitted by the device.Type: GrantFiled: June 8, 2008Date of Patent: January 3, 2012Assignee: The United States of America as represented by the Administrator of the National Aeuronautics and Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, Sang-Hyon Chu
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Patent number: 8059273Abstract: A spectrometer system includes an optical assembly for collimating light, a micro-ring grating assembly having a plurality of coaxially-aligned ring gratings, an aperture device defining an aperture circumscribing a target focal point, and a photon detector. An electro-optical layer of the grating assembly may be electrically connected to an energy supply to change the refractive index of the electro-optical layer. Alternately, the gratings may be electrically connected to the energy supply and energized, e.g., with alternating voltages, to change the refractive index. A data recorder may record the predetermined spectral characteristic.Type: GrantFiled: July 2, 2009Date of Patent: November 15, 2011Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott
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Patent number: 8044294Abstract: New thermoelectric materials comprise highly [111]-oriented twinned group IV alloys on the basal plane of trigonal substrates, which exhibit a high thermoelectric figure of merit and good material performance, and devices made with these materials.Type: GrantFiled: October 20, 2008Date of Patent: October 25, 2011Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott, Noel A. Talcott
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Patent number: 8020805Abstract: A new High Altitude Airship (HAA) capable of various extended applications and mission scenarios utilizing inventive onboard energy harvesting and power distribution systems. The power technology comprises an advanced thermoelectric (ATE) thermal energy conversion system. The high efficiency of multiple stages of ATE materials in a tandem mode, each suited for best performance within a particular temperature range, permits the ATE system to generate a high quantity of harvested energy for the extended mission scenarios. When the figure of merit 5 is considered, the cascaded efficiency of the three-stage ATE system approaches an efficiency greater than 60 percent.Type: GrantFiled: July 31, 2007Date of Patent: September 20, 2011Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Sang H. Choi, James R. Elliott, Jr., Glen C. King, Yeonjoon Park, Jae-Woo Kim, Sang-Hyon Chu
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Patent number: 8018815Abstract: An embodiment generally relates to an optical device suitable for use with an optical medium for the storage and retrieval of data. The optical device includes an illumination means for providing a beam of optical radiation of wavelength ? and an optical path that the beam of optical radiation follows. The optical device also includes a diffractive optical element defined by a plurality of annular sections. The plurality of annular sections having a first material alternately disposed with a plurality of annular sections comprising a second material. The diffractive optical element generates a plurality of focal points and densely accumulated ray points with phase contrast phenomena and the optical medium is positioned at a selected focal point or ray point of the diffractive optical element.Type: GrantFiled: June 24, 2009Date of Patent: September 13, 2011Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Sang H. Choi, Yeonjoon Park, Glen C. King, James R. Elliott
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Patent number: 7998368Abstract: Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.Type: GrantFiled: November 18, 2008Date of Patent: August 16, 2011Assignee: United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Jae-Woo Kim, Cheol Park, Sang H. Choi, Peter T. Lillehei, Joycelyn S. Harrison
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Patent number: 7906358Abstract: Hetero-epitaxial semiconductor materials comprising cubic crystalline semiconductor alloys grown on the basal plane of trigonal and hexagonal substrates, in which misfit dislocations are reduced by approximate lattice matching of the cubic crystal structure to underlying trigonal or hexagonal substrate structure, enabling the development of alloyed semiconductor layers of greater thickness, resulting in a new class of semiconductor materials and corresponding devices, including improved hetero-bipolar and high-electron mobility transistors, and high-mobility thermoelectric devices.Type: GrantFiled: October 20, 2008Date of Patent: March 15, 2011Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King
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Publication number: 20110024609Abstract: An optical apparatus includes an optical diffraction device configured for diffracting a predetermined wavelength of incident light onto adjacent optical focal points, and a photon detector for detecting a spectral characteristic of the predetermined wavelength. One of the optical focal points is a constructive interference point and the other optical focal point is a destructive interference point. The diffraction device, which may be a micro-zone plate (MZP) of micro-ring gratings or an optical lens, generates a constructive ray point using phase-contrasting of the destructive interference point. The ray point is located between adjacent optical focal points. A method of generating a densely-accumulated ray point includes directing incident light onto the optical diffraction device, diffracting the selected wavelength onto the constructive interference focal point and the destructive interference focal point, and generating the densely-accumulated ray point in a narrow region.Type: ApplicationFiled: July 30, 2009Publication date: February 3, 2011Applicants: Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott
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Publication number: 20100197508Abstract: Integrated universal chemical detector in a micro-optical chip in which chemical/bio-sensitive micro/nano-pixels are aligned to create diffraction patterns that can be visually or instrumentally categorized in order to identify a substantial plurality of agents. By using a diffraction method to create a macroscopic diffraction image, a single small array can effectively detect hundreds or even thousands of different chemicals. The apparatus can be further automated by analyzing the diffraction patterns electronically.Type: ApplicationFiled: February 3, 2009Publication date: August 5, 2010Applicant: The Administrator of the National Aeronautics and Space Administration, United States of AmericaInventors: Dustin S. Carter, Yeonjoon Park, Glen C. King, Sang H. Choi
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Publication number: 20100118683Abstract: An embodiment generally relates to an optical device suitable for use with an optical medium for the storage and retrieval of data. The optical device includes an illumination means for providing a beam of optical radiation of wavelength ? and an optical path that the beam of optical radiation follows. The optical device also includes a diffractive optical element defined by a plurality of annular sections. The plurality of annular sections having a first material alternately disposed with a plurality of annular sections comprising a second material. The diffractive optical element generates a plurality of focal points and densely accumulated ray points with phase contrast phenomena and the optical medium is positioned at a selected focal point or ray point of the diffractive optical element.Type: ApplicationFiled: June 24, 2009Publication date: May 13, 2010Inventors: Sang H. Choi, Yeonjoon Park, Glen C. King, James R. Elliott
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Publication number: 20100039643Abstract: A spectrometer system includes an optical assembly for collimating light, a micro-ring grating assembly having a plurality of coaxially-aligned ring gratings, an aperture device defining an aperture circumscribing a target focal point, and a photon detector. An electro-optical layer of the grating assembly may be electrically connected to an energy supply to change the refractive index of the electro-optical layer. Alternately, the gratings may be electrically connected to the energy supply and energized, e.g., with alternating voltages, to change the refractive index. A data recorder may record the predetermined spectral characteristic.Type: ApplicationFiled: July 2, 2009Publication date: February 18, 2010Applicant: US of America as represented by the Administratior of the National Aeronautics & Space AdministratioInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott
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Publication number: 20100039644Abstract: A spectrometer system includes an array of micro-zone plates (MZP) each having coaxially-aligned ring gratings, a sample plate for supporting and illuminating a sample, and an array of photon detectors for measuring a spectral characteristic of the predetermined wavelength. The sample plate emits an evanescent wave in response to incident light, which excites molecules of the sample to thereby cause an emission of secondary photons. A method of detecting the intensity of a selected wavelength of incident light includes directing the incident light onto an array of MZP, diffracting a selected wavelength of the incident light onto a target focal point using the array of MZP, and detecting the intensity of the selected portion using an array of photon detectors. An electro-optic layer positioned adjacent to the array of MZP may be excited via an applied voltage to select the wavelength of the incident light.Type: ApplicationFiled: July 23, 2009Publication date: February 18, 2010Applicant: United States of America as represented by the Administrator of the National Aeronautics and SpacInventors: Sang H. Choi, Yeonjoon Park, Glen C. King, James R. Elliott
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Publication number: 20100039641Abstract: A spectrometer includes a micro-ring grating device having coaxially-aligned ring gratings for diffracting incident light onto a target focal point, a detection device for detecting light intensity, one or more actuators, and an adjustable aperture device defining a circular aperture. The aperture circumscribes a target focal point, and directs a light to the detection device. The aperture device is selectively adjustable using the actuators to select a portion of a frequency band for transmission to the detection device. A method of detecting intensity of a selected band of incident light includes directing incident light onto coaxially-aligned ring gratings of a micro-ring grating device, and diffracting the selected band onto a target focal point using the ring gratings. The method includes using an actuator to adjust an aperture device and pass a selected portion of the frequency band to a detection device for measuring the intensity of the selected portion.Type: ApplicationFiled: June 19, 2009Publication date: February 18, 2010Applicant: United States of America as represented by the Adminstrator of the National Aeronautics and SpaceInventors: Yeonjoon Park, Glen C. King, James R. Elliott, Sang H. Choi
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Publication number: 20090303598Abstract: A dynamic optical grating device and associated method for modulating light is provided that is capable of controlling the spectral properties and propagation of light without moving mechanical components by the use of a dynamic electric and/or magnetic field. By changing the electric field and/or magnetic field, the index of refraction, the extinction coefficient, the transmittivity, and the reflectivity of the optical grating device may be controlled in order to control the spectral properties of the light reflected or transmitted by the device.Type: ApplicationFiled: June 8, 2008Publication date: December 10, 2009Applicant: USA as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, Sang-Hyon Chu
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Publication number: 20090231677Abstract: An optical assembly includes a zone plate and electro-optic material disposed on one side of the zone plate. The electro-optic material's index of refraction is controlled to adjust the optical properties of the optical assembly.Type: ApplicationFiled: March 13, 2008Publication date: September 17, 2009Applicant: USA as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott
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Publication number: 20090220047Abstract: “Super-hetero-epitaxial” combinations comprise epitaxial growth of one material on a different material with different crystal structure. Compatible crystal structures may be identified using a “Tri-Unity” system. New bandgap engineering diagrams are provided for each class of combination, based on determination of hybrid lattice constants for the constituent materials in accordance with lattice-matching equations. Using known bandgap figures for previously tested materials, new materials with lattice constants that match desired substrates and have the desired bandgap properties may be formulated by reference to the diagrams and lattice matching equations. In one embodiment, this analysis makes it possible to formulate new super-hetero-epitaxial semiconductor systems, such as systems based on group IV alloys on c-plane LaF3; group IV alloys on c-plane langasite; Group III-V alloys on c-plane langasite; and group II-VI alloys on c-plane sapphire.Type: ApplicationFiled: October 20, 2008Publication date: September 3, 2009Applicants: Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott
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Publication number: 20090203196Abstract: Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.Type: ApplicationFiled: December 4, 2008Publication date: August 13, 2009Applicants: National Institute of Aerospace Associates, USA as represented by the Administrator of the National Aeronautics and Space AdministrationInventors: Jae-Woo KIM, Sang H. CHOI, SR., Peter T. LILLEHEI, Sang-Hyon CHU, Yeonjoon PARK, Glen C. KING, James R. ELLIOTT, JR.
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Publication number: 20090165837Abstract: New thermoelectric materials comprise highly [111]-oriented twinned group IV alloys on the basal plane of trigonal substrates, which exhibit a high thermoelectric figure of merit and good material performance, and devices made with these materials.Type: ApplicationFiled: October 20, 2008Publication date: July 2, 2009Applicants: Space AdministrationInventors: Yeonjoon Park, Sang H. Choi, Glen C. King, James R. Elliott, Noel A. Talcott