Abstract: Provided is a method for forming solid substrates having high density of primary amine group on its surface, in which the primary amine groups on the surface of an aminosilylated substrate are treated with aziridine or an aziridine derivative. The surface density of the primary amine functional groups (—NH2) on the very top surface of a substrate can be drastically increased.

Abstract: A fin tube heat exchanger includes plate-shaped elongated fin members spaced at regular intervals, in parallel with one another. Each fin member has a fin base, through-holes in two rows in a longitudinal direction of the fin member, and raised portions with legs. Heat exchanger tubes are inserted into the through-holes. Each fin member has flat areas at a front and middle regions of a front half and a middle region of a rear half. The raised portion disposed at a rear region of the front half and a front region of the rear half has the legs inclined by a predetermined angle with respect to a traverse centerline which passes through the center of an adjacent through-hole of the front row. The distance from the centerline generally increases with a direction of airflow. A larger volume of air can be directed toward the vicinity of the tubes of the rear row. Each fin member has a front edge and a rear edge.

Abstract: A gallium nitride (GaN) based optical device and a fabrication method thereof are provided. The GaN based optical device includes a substrate, a p-type GaN (p-GaN) layer formed on the substrate, and a p-type ohmic electrode formed on the p-GaN layer, wherein the p-type ohmic electrode is formed of a triple layer comprised of a nickel (Ni) layer, a gold (Au) layer and an indium tin oxide (ITO) layer sequentially formed. The thicknesses of the Ni layer and the Au layer forming the triple layer are smaller than the thickness of the ITO layer. When the p-type ohmic electrode in the GaN based optical device is formed of a triple layer comprised of Ni/Au/ITO, the Ni/Au layers reduce contact resistance and the ITO, which is a transparent, conductive oxide layer, increases transparency and increases luminescence efficiency.

Abstract: A p-type ohmic electrode in a gallium nitride based(GaN based) optical device and a fabrication method thereof. The p-type ohmic electrode in a GaN based optical device is fabricated using a rutile structure transition metal layer, such as an Ru, Ir or Os layer, or an oxide layer thereof, or using a double layer comprised of an Ru layer as a base layer and an Ni layer, an ITO layer or an AuO layer on the Ru layer. Thus, the p-type ohmic electrode is good in light transmittance and is thermally stable while having low contact resistance with the p-GaN layer.

Abstract: A single-stage converter improving the power factor is provided. The single-stage converter comprises a power factor improving unit, a bridge diode unit, a voltage smoothing condenser, a transformer circuit unit, and a main switch. The power factor improving unit is connected to a predetermined input power source, the bridge diode unit is located next to the power factor improving unit and provides a current path, the voltage smoothing condenser stores electric energy provided through the bridge diode unit, the transformer circuit unit is located between the bridge diode unit and the voltage smoothing condenser, and the main switch is connected to each of the bridge diode unit, the voltage smoothing condenser, and the transformer circuit unit and controls provision of voltage to the transformer circuit unit. Thus, the single-stage converter can improve the power factor of the input terminal.

Abstract: An apparatus for measuring thermal properties and making thermomechanical modifications on a material surface using a junction of different metallic wires. The junction of different metallic wires, defined as a Peltier tip, is distinguished from a conventional thermocouple by the fact that it works as a point heat source and as a point temperature sensor simultaneously when an electric current flows into the tip. This novel functionality of the Peltier tip offers a way to thermally characterize a material surface with submicron-scale spatial resolution and high sensitivity, while providing high spatial resolution and speed for thermal modifications since both heating and cooling are possible at the Peltier tip.

Abstract: A sensor prevents automobile crashes by collecting information such as a distance between automobiles, speed, and acceleration by utilizing a phenomenon that a photonic quantum ring laser emits light rays having different wavelengths associated with varying angles of the radiation from the photonic quantum ring. The sensor for preventing automobile crashes includes a photonic quantum ring laser array for lasing light beams having different wavelengths according to the view angle, a reflection unit for reflecting the light beams oscillated from the photonic quantum ring laser array, and a detection unit for detecting the light beams reflected by the reflection unit.

Abstract: A method for manufacturing a hetero-junction field effect transistor (HFET) device, which includes sequentially forming a non-doped GaN semiconductor layer and an AlGaN semiconductor layer on a substrate, separating devices from each other by etching the substrate, forming a photoresist layer pattern on the AlGaN semiconductor layer and forming gate electrodes by depositing a material on the substrate using the photoresist layer pattern, treating the surface of the AlGaN semiconductor layer, and forming a photoresist layer pattern on the substrate and forming ohmic electrodes by depositing a metal on the substrate using the photoresist layer pattern, is provided. Accordingly, it is possible to overcome a difficulty in aligning the gate electrode with the ohmic electrodes and prevent a substrate from having a step difference introduced by the ohmic electrodes because the gate electrode is formed before the ohmic electrodes are formed.

Abstract: Provided is a sample clean-up apparatus for removing low-molecular weight substances such as salts from high-molecular weight biological samples such as proteins by simple molecular diffusion in a laminar flow channel and enabling solvent exchange for samples to be suitable for mass spectrometry.

Abstract: A high-efficiency, high-sensitivity absorbance detection system in a lab-on-a-chip is provided. The absorbance detection system includes detection cells having an optical pathlength ten times and/or much longer than the width of a separation channel to improve detection sensitivity, lens structures for collimating light in the detection cells, and slit structures for preventing scattered light from entering detectors. The detection cells, the lens structures, and the slit structures of the absorbance detection system are fabricated and integrated in a lab-on-a-chip. The absorbance detection system exhibits excellent absorption efficiency, detection limit, and linearity, compared to existing absorbance detection systems, and can be applied for the detection of a variety of samples. The absorbance detection system does not need labeling of the samples which saves time and costs. The absorbance detection system can be used effectively in detecting trace compounds with a high sensitivity.

Abstract: A programmable high speed frequency divider, in which flip-flops for forming a frequency divider which is capable of being programmed with a programmable dividing ratio is simplified increase the speed of the frequency divider. By simplifying the least significant bit flip-flops, including the flip-flop representing the least significant bit, among flip-flops forming a frequency divider, the speed of the counter in the frequency divider is increased and the frequency limit of an input clock which can be divided is raised.

Abstract: A linear amplifier using a low frequency 2nd intermodulation feed-forwarding method to offset the 3rd intermodulation component of a fundamental signal is provided. This linear amplifier includes a transistor for amplifying the power of the fundamental signal, a first filter unit, one end of which is connected to the gate of the transistor, for filtering a 2nd order intermodulation signal from the fundamental signal, a low frequency amplifier connected to the other end of the first filter unit, for amplifying the 2nd order intermodulation signal with a predetermined voltage gain, and a second filter unit connected in series between the output port of the low frequency amplifier and the drain output port of the transistor, for filtering the amplified 2nd intermodulation signal and feeding the same to the output port of the transistor.

Abstract: A thermal conduction vacuum gauge using a Peltier tip is provided. The vacuum gauge for measuring the pressure in a vacuum chamber includes: a signal generator that drives an electric current; an ammeter connected to the signal generator for measuring the current; a bridge circuit consisting of junctions of thermocouple wires, which is connected to the ammeter, wherein one junction of the dissimilar metallic wires is made in the form of a Peltier tip inserted into the vacuum chamber; and a lock-in amplifier connected to the two symmetrical points of the bridge circuit for detecting a voltage signal due to the temperature oscillation at the Peltier tip and thus measuring the pressure in the vacuum chamber.

Abstract: A remote center compliance system having a variable center, an upper plate, a lower plate, and elastic bodies installed between the upper and lower plates, includes lower rotary plates, each having a rotation axis parallel to a center axis passing the center of the lower plate and the center of the upper plate, coupled to a lower end of each of the elastic bodies and coupled to the lower plate for rotating, and upper rotary plates, each being coupled to an upper end of each of the elastic bodies and concurrently coupled to the upper plate for rotating about the rotation axis of the lower rotary plate. A center axis of each of the elastic bodies is inclined with respect to the rotation axis of the lower rotary plate to which each of the elastic bodies is coupled. Thus, when parts having different lengths are to be assembled, the assembly of the parts can be easily performed only by rotating the rotary plates and the elastic bodies without changing the RCA system to cope with various lengths of the parts.

Abstract: A method for forming a chromium oxide film on the surface of a stainless steel sample. The method includes: (a) placing a sample having stainless a steel surface into a vacuum furnace, evacuating the vacuum furnace to a pressure of 2×10−7 to 3×10−7 Torr, and heating the vacuum furnace to 450 to 600° C. at a rate of 5 to 10° C./min; (b) maintaining the vacuum furnace for 10 to 20 minutes at a temperature of 450 to 600° C. to remove foreign materials from the surface of the stainless steel sample and to extract chromium atoms from the stainless steel substrate; and (c) supplying oxygen to the vacuum furnace while maintaining the temperature until oxygen partial pressure reaches 1×10−9 to 2.5×10−7 Torr, so the extracted chromium atoms react with oxygen, producing a chromium oxide (Cr2O3) film on the surface of the stainless steel.

Abstract: Cucurbituril derivatives, their preparation methods and uses.

Abstract: A programmable high speed frequency divider, in which the construction of flip-flops for forming a frequency divider which is capable of programming the dividing ratio of an input clock frequency is simplified in order to increase the operation speed of the frequency divider, is provided. By simplifying the structures of least significant bit flip-flops, including the flip-flop representing the least significant bit, among flip-flops forming a frequency divider, the operation speed of the counter in the frequency divider is increased and the frequency limit of an input clock which can be divided is raised.

Abstract: An apparatus and method for measuring an electrochemical impedance at high speed. The method for measuring the electrochemical impedance of an electrolyte at high speed includes applying a direct current (DC) voltage having the reaction potential of the electrolyte to the electrolyte via a counter electrode and, after a delay, applying a signal voltage, including a DC voltage added to a differentiated or integrated Dirac-delta function voltage, to the electrolyte; computing a digital data value related only to the differentiated or integrated Dirac-delta function voltage, obtained by converting signal current flowing in a working electrode via the electrolyte into a voltage, integrating or differentiating the voltage, and Fourier transforming the result of the integration or differentiation; and obtaining changes in magnitude and phase as a function of frequency based on the Fourier transform, to compute the impedance.

Abstract: A current-mode bidirectional input/output buffer circuit for impedance matching and operation at a high speed. The current-mode bidirectional input/output buffer circuit communicates with an external chip having the same current-mode bidirectional input/output buffer. In the buffer, a transmitting-receiving average voltage output unit converts an average current value between a transmission signal to be transmitted to the external chip and a receiving signal transmitted from the external chip, into an average voltage. A reference voltage output unit converts a reference current value selectively generated according to a voltage level of the transmission signal, into a reference voltage. A comparator compares the voltage from the transmitting-receiving average voltage output unit to the voltage from the reference voltage output unit to provide a logic signal corresponding to the received signal transmitted from the external chip.