• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.99-104
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• 2003

A precision displacement measurement system of 3-DOF micro motions is proposed in this paper. The measurement system is composed of two diode lasers, two quadratic PSDs, two beam splitters and a sphere whose surface is highly reflective. In this measurement system, the sphere reflector is mounted on the platform of positioning devices whose 3-DOF translational motions are to be measured, and the sensitive areas of two PSDs are oriented toward the center point of the sphere reflector. Each laser beam emitted from two diode laser sources is reflected at the surface of sphere and arrives at two PSDs. Each PSD serves as a 2-dimensional sensor, providing the information on the 3-dimensional position of the sphere. In this paper, we model the relationship between the outputs of two PSDs and 3-DOF translational motions of the sphere mounted on the object. Based on a deduced measurement model, we perform measurement simulation and evaluate the performance of the proposed measurement system: linearity, sensitivity, and measurement error. The simulation results show that the proposed measurement system can be valid means of precision displacement measurement of 3-dimensional micro motions.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.97-103
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• 2002

In this paper, a Logarithmic Video Amplifier(LVA) for radar system or satellite communications is described. The proposed LVA is composed of a input stage, amplification stage, and output stage. As well as a novel series-parallel architecture is proposed for the purpose of wide dynamic range and high speed operation, a newly developed input stage is designed in order to control the voltage level between LVA and detector diode. The LVA is fabricated with a 1.5um 2-poly 2-metal n-well Bi-CMOS technology, and the chip area is 1310 um x 1540 um. From the experimental results, it consumes 190 mW at 10V power supply, the chip has 60 dB dynamic range and 100ns falling time.

• Natural Product Sciences
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• v.19 no.3
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• pp.236-241
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• 2013

A high-performance liquid chromatography-diode array detector (HPLC-DAD) method was established for quantitative evaluation of nine constituents of Fraxinus rhynchophylla such as four coumarins, esculin (1), fraxin (2), esculetin (3), fraxetin (4), three lignans, syringaresinol 4,4'-O-${\beta}$-diglucoside (5), pinoresinol 4-O-${\beta}$-glucoside (6), pinoresinol (9), one secoiridoid, oleuropein (7), and one coumarinolignan, cleomiscosin C (8). The preferred chromatographic condition was obtained on Phenomenex Gemini-NX (3 ${\mu}m$, C18 110A, $150{\times}4.60$ mm) and the mobile phase was composed of water and acetonitrile using a gradient elution. The wavelength was set at 220 nm. Extraction condition of these constituents in F. rhynchophylla was also optimized through extraction time, extraction solvent and extraction method using established method. From this study, extraction at $70^{\circ}C$ with the mixture of ethanol and water for more than 12 h was suggested to be good extraction condition for these constituents. Quantitation of nine constituents in different F. rhynchophylla samples was also successfully accomplished with the newly established method.

• Natural Product Sciences
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• v.16 no.3
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• pp.164-168
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• 2010

High-performance liquid chromatographic method with diode-array detector and electrospray ionization with multi-stage tandem mass spectroscopy (HPLC/DAD/ESI-$MS^n$) was used to identify the major constituents in a methanolic extract of Eclipta prostrata. The chromatographic separation was performed on a C18 column. Acetonitrile-water was used as a mobile phase. HPLC/DAD/ESI-$MS^n$ allowed the characterization of constituents of E. prostrata, mainly triterpenoids (eclalbasaponin I, II, III, IV, VI), flavonoids (luteolin 7-O-glucoside, demethylwedelolactone, wedelolactone, luteolin, demetylwedelolactone sulfate, luteolin sulfate, apigenin sulfate) and phenolic acids (5-O-caffeoylquinic acid, 3, 4-O-dicaffeoylquinic acid, 3, 5-O-dicaffeoylquinic acid, 4, 5-Odicaffeoylquinic acid).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.484-493
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• 2004

A new lightwave locking technique which can be used in tuning the wavelength of a local laser diode to the reference wavelength is presented in this paper. The optical frequency from the reference laser source and the optical frequency from the local slave VCO laser are heterodyned on a optical receiver, resulting in the 1.5GHz RF signal corresponding to the difference frequency between two input optical signals. The difference frequency is locked to the reference 1.5GHz oscillator source in off-set frequency locking loop. Using the commercialized microwave components, frequency difference detector can be easily established to lock the lightwave. The optical frequency of 1.55um laser diode which keeps the frequency off-set of 1.5GHz is locked to the input reference optical signal with the locking range of 320MHz.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.1
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• pp.40-46
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• 1974

This paper deals with the self-excited mixer using tunnel diode oscillator operated as a microwave source and Doppler signal detector. The system impedance, the oscillation condition and the frequency conversion theory including moving target are investigated. The oscillating frequency and the output of tunnel diode oscillator are 2.035 GHz and 0.1 mW. The input signal frequency which is equivalent to Doppler signal is lower than tunnel diode oscillator frequency by 125 MHz. TDe conversion loss has been investigated as a functicn of input signal level. This loss is greater than 67 db for the large pump mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.377-377
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• 2007

A simplified integration process including packaging is presented, which enables the realization of the portable fluorescence detection system. A fluorescence detection microchip system consisting of an integrated PIN photodiode, an organic light emitting diode (OLED) as the light source, an interference filter, and a microchannel was developed. The on-chip fluorescence detector fabricated by poly(dimethylsiloxane) (PDMS)-based packaging had thin-film structure. A silicon-based integrated PIN photo diode combined with an optical filter removed the background noise, which was produced by an excitation source, on the same substrate. The active area of the finger-type PIN photo diode was extended to obtain a higher detection sensitivity of fluorescence. The sensitivity and the limit of detection (LOD S/N = 3) of the system were $0.198\;nA/{\mu}M$ and $10\;{\mu}M$, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.12
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• pp.545-552
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• 2003

When a Si PIN diode is exposed to fast neutrons, it results in displacement damage to the Si lattice structure of the diode. Defects induced from structural dislocation become effective recombination centers for carriers which pass through the base of a PIN diode. Hence, increasing the resistivity of the diode decreases the current for the applied forward voltage. This paper involves the development of a neutron sensor based on the phenomena of the displacement effect damaged by neutron exposure. The neutron effect on the semiconductor was analyzed. Several PIN diode arrays with various thickness and cross-section area of the intrinsic layer(I layer) were fabricated. Under irradiation tests with a neutron beam, the manufactured diodes have a good linearity to neutron dose and show that the increase of thickness of I layer and the decrease of cross-section of PIN diodes improve the sensitivity. Newly developed PIN diodes with thicker I layer and various cross section, were retested and then showed the best neutron sensitivity at the condition that the I layer thickness was similar to a side length. On the basis of two test results, final discrete PIN diodes with a rectangular shape were manufactured and the characteristics as neutron detectors were analyzed through the neutron beam test using on-line electronic dosimetry system. Developed PIN diode shows a good linearity as dosimetry in the range of 0 to 1,000cGy(Tissue) and its neutron sensitivity is 13mV/cGy at constant current of 5mA, that is three times higher than that of commercially available neutron detectors. And the device shows little dependency on the orientation of the neutron beam and a considerable stability in annealing test for a long period.

• Korean Journal of Optics and Photonics
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• v.35 no.2
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• pp.61-70
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• 2024

We demonstrate a laser power meter calibration system based on 12-diode laser sources coupled to single-mode fibres in a wavelength range from 400 to 1,600 nm. In our system, three laser power controllers ensure that the output power uncertainty of all laser sources is less than 0.1% (k=2). In addition, all laser beams are adjusted to have similar beam sizes of approximately 2 mm (1/e²-width) at the measurement position to minimise unmeasured laser power on a detector. As a reference detector, we use an integrating sphere combined with silicon and indium gallium arsenide photodiodes to minimise the non-uniformity and non-linearity of responsivity. The minimum uncertainty of the calibration system is estimated to be 1.1% (k=2) for most laser wavelengths.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.10-17
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• 2009

Transillumination system used by radiation is widely applied to industrial imaging system. In this study, the linear detector array constructed with scintillator and pin diode, and a multi-channel data acquisition system was developed for precision inspection of end-milling. The detector module consists of $16-CdWO_4$crystal scintillator and photodiode array. The detector and data acquisition system was applied to precision inspection of end-mill and the images of the end-mill were successfully reconstructed. The total system can analyze the Detector Quantum Efficiency(DQE) of each system. The performance of developed photodiodes equipment was compared with each other for different crystal geometry and its characteristics. Finally fine details of the end-mill phantom were constructed for industrial application. The image acquired contains several objects on a real time data transfer and the linear X-ray scanning system can be applied to many fields of a industry.