• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.635-645
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• 2016

In this paper, we showed the phase noise of voltage controlled oscillator(VCO) can be radically improved using FLL(Frequency Locked Loop). At first, a 5 GHz VCO is fabricated using a hair-pin resonator. The fabricated VCO shows a phase noise of -53.1 dBc/Hz at 1 kHz frequency offset. In order to improve the phase noise of the fabricated VCO, a FLL is constructed using the feedback loop that consists of the VCO, a frequency detector composed of 5 GHz resonator, loop-filter, and level shifter. The fabricated FLL is designed to oscillate at a frequency of 5 GHz, and its measured phase noise is about -120.6 dBc/Hz at 1 kHz offset frequency. As a result, the phase noise of VCO can be radically improved by about 67.5 dB applying FLL. In addition, the measured phase noise performance is close to that of crystal oscillator.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.3 s.333
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• pp.25-32
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• 2005

In this papers, we first, therefore, designed VCO(voltage controlled oscillator) that is composed of the dielectric resonator and the varactor diode, and then designed and fabricated PLDRO(phase locked dielectric resonator oscillator) that is combined with the sampling phase detector and loop filter. The measured results of the fabricated PLDRO at 12.05 [GHz] show the output power is 13.54 [dBm], frequency tuning range approximately +/- 7.5 [MHz], and Power variation over the tuning range less than 0.2 [dB], respectively. The phase noise which effects on bits error rate in digital communication is obtained with -114.5 [dBc/Hz] at 100 [KHz] offset from carrier, and The second harmonic suppression is less than -41.49 [dBc]. These measured results are found to be more improved than those of VCO without adopting PLL, and the phase noise and power variation performance characteristics show the better performances than those of conventional PLL.

• Journal of Digital Contents Society
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• v.19 no.8
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• pp.1603-1615
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• 2018

In order to achieve the low complexity and area, power in the design of Optical Image Stabilization (OIS) suitable for the smart phone, this paper presents the following design explorations, such as; optimization of gyroscope sampling rate, simple and accurate gyroscope filters, and reduced operating frequency of motion compensation, optimized bit width in ADC and DAC, evaluation of noise effects due to PWM driving. In experiments of gyroscope sampling frequencies, it is found that error values are unvaried in the frequency above 5KHz. The gyroscope filter is efficiently designed by combining the Fuzzy algorithm, to illustrate the reasonable compensation for the angle and phase errors. Further, in the PWM design, the power consumption of 2MHz driving is shown to decrease up to 50% with respect to the linear driving, and the imaging noises are reduced in the driving frequency above 2MHz driving frequency. The operating frequency could be reduced to 5KHz in controller and 10KHz in driver, respectively, in the motion compensation. For ADC and DAC, the optimized exploration experiments verify the minimum bit width of 11bits in ADC as well as 10bits in DAC without the performance degradation.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.40.1-40.1
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• 2010

The Main payload of the STSAT-3 (Korea Science & Technology Satellite-3), MIRIS (Multipurpose Infra-Red Imaging System) has been developed for last 3 years by KASI, and its Flight Model (FM) is now being developed as the final stage. All optical lenses and the opto-mechanical components of the FM have been completely fabricated with slight modifications that have been made to some components based on the Engineering Qualification Model (EQM) performances. The components of the telescope have been assembled and the test results show its optical performances are acceptable for required specifications in visual wavelength (@633 nm) at room temperature. The ensuing focal plane integration and focus test will be made soon using the vacuum chamber. The MIRIS mechanical structure of the EQM has been modified to develop FM according to the performance and environment test results. The filter-wheel module in the cryostat was newly designed with Finite Element Analysis (FEM) in order to compensate for the vibration stress in the launching conditions. Surface finishing of all components were also modified to implement the thermal model for the passive cooling technique. The FM electronics design has been completed for final fabrication process. Some minor modifications of the electronics boards were made based on EQM test performances. The ground calibration tests of MIRIS FM will be made with the science grade Teledyne PICNIC IR-array.

• Journal of Environmental Health Sciences
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• v.42 no.1
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• pp.53-60
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• 2016

Objectives: Preservatives are commonly used in pharmaceuticals, cosmetics and other products to extend the expiration date and prevent the growth of microorganisms. Preservatives are generally effective in controlling mold and inhibiting yeast growth, and against a wide range of bacterial attacks as well. They also adversely affect the quality of sperm and cause precocious puberty in children. This study was performed to analyze seven preservatives used in pharmaceuticals and personal care products. Methods: Five kinds of pharmaceuticals and personal care products (PPCPs) were examined for analysis with a high performance liquid chromatography-diode array detector. Each sample was homogenized and the targeted compounds were extracted with methanol. The suspended particulate was removed by syringe filter. Next, the sample was injected into an HPLC system. The separation of the seven preservatives was achieved with a C18 column and gradient mode. The accuracies were between 73% and 120% and precision was lower than 11.58% (RSD). Results: All of the calibration curves showed good linearity with a coefficient of determination ($r^2$) over 0.999. Among the PPCP samples, the detection rate of preservatives was 32.5% for pharmaceuticals, 44.8% for toothpaste, 76.9% for mouthwash, 40.0% for body lotion and 56.0% for wet tissues. The average concentrations of the preservatives in PPCPs were BA 1141.0 mg/kg, MP 709.8 mg/kg, EP 624.9 mg/kg, PP 216.9 mg/kg, BP 167.8 mg/kg, and TCS 538.2 mg/kg. The most frequently detected preservatives in pharmaceuticals and personal care products were BA, MP and PP. The concentrations of preservatives exceeded Korean regulatory standards in 11 samples of medicines, three of mouthwash and two of body lotion. Conclusion: We found that most of the PPCP samples contained various preservatives. It is necessary to identify which preservatives were used and to determine the level of preservatives in PPCPs and to assess the health risk to susceptible populations such as children.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.35-48
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• 2013

Biodiesel is an alternative diesel fuel which can be obtained from the transesterification of vegetable oils, animal fats and waste cooking oil. The objective of this study is to evaluate the properties of biodiesel obtained from different feedstocks (soybean, waste cooking, rapeseed, cottonseed and palm oils). The biodiesel derived from different feedstocks was analyzed for FAME (fatty acid methyl esther) content, kinematic viscosity, flash point, CFPP (cold filter plugging point) and glycerin content. The quality of biodiesel was tested according to the Korean and European standard (EN14214, requirements and test method for biodiesel fuel). The biodiesels derived from soybean, waste cooking, rapeseed and cottonseed oils contain high amount of unsaturated fatty acid, while palm biodiesel is dominated by saturated fatty acid. The fuel properties of biodiesel, such as low temperature performance, kinematic viscosity and oxidation stability are correlated with the FAME composition components in biodiesel.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.319-326
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• 2004

To help network intrusion detection systems(NIDSs) keep up with the demands of today's networks, that we the increasing network throughput and amount of attacks, a radical new approach in hardware and software system architecture is required. In this paper, we propose a Network Processor(NP) based In-Line mode NIDS that supports the packet payload inspection detecting the malicious behaviors, as well as the packet filtering and the traffic metering. In particular, we separate the filtering and metering functions from the deep packet inspection function using two-level searching scheme, thus the complicated and time-consuming operation of the deep packet inspection function does not hinder or flop the basic operations of the In-line mode system. From a proto-type NP-based NIDS implemented at a PC platform with an x86 processor running Linux, two Gigabit Ethernet ports, and 2.5Gbps Agere PayloadPlus(APP) NP solution, the experiment results show that our proposed scheme can reliably filter and meter the full traffic of two gigabit ports at the first level even though it can inspect the packet payload up to 320 Mbps in real-time at the second level, which can be compared to the performance of general-purpose processor based Inspection. However, the simulation results show that the deep packet searching is also possible up to 2Gbps in wire speed when we adopt 10Gbps APP solution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.27-36
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• 2019

The demand for a low dispersion lens with a small refractive index and a high refractive index is increasing, and accordingly, there is an increasing need for a releasable protective film with high heat resistance and abrasion resistance. On the other hand, the optical industry has not yet established a clear standard for the manufacturing process and quality standards for mold-releasing protective films used in aspheric glass lens molding. Optical lens manufacturers treat this technology as proprietary information. In this study, an experiment was conducted regarding the optimization of ion etching, magnetron, and arc current at each source and filter part, and bias voltage in FCVA (filtered cathode vacuum arc)-based Ta-C thin film coatings. This study found that compared to iridium-rhenium alloy thin film sputtering products, the coating conditions were improved by approximately 50%, 20%, and 40% in terms of thickness, hardness, and adhesive strength of the film, respectively. The thin-film coating process proposed in this study is expected to contribute significantly to the development and utilization of glass lenses, which will help enhance the minimum mechanical properties and quality of the mold-release thin film layer required for glass mold surface forming technology.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.571-575
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• 2016

Monte Carlo simulations are widely used as the most accurate technique for dose calculation in radiation therapy. In this paper, the GATE6(Geant4 Application for Tomographic Emission ver.6) code was employed to calculate the dosimetric performance of the photon beams from a linear accelerator(LINAC). The treatment head of a Varian 21EX Clinac was modeled including the major geometric structures within the beam path such as a target, a primary collimator, a flattening filter, a ion chamber, and jaws. The 6 MV photon spectra were characterized in a standard $10{\times}10cm^2$ field at 100 cm source-to-surface distance(SSD) and subsequent dose estimations were made in a water phantom. The measurements of percentage depth dose and dose profiles were performed with 3D water phantom and the simulated data was compared to measured reference data. The simulated results agreed very well with the measured data. It has been found that the GATE6 code is an effective tool for dose optimization in radiotherapy applications.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.355-363
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• 2015

Advancement in the medical field provides an opportunity for the development of medical equipment and also enable accurate diagnosis for the inspection and the treatment of diseases. The aging of equipment due to the frequent operation produce uncertainty in the patient exposure dose, so a quality control was implemented by establishing a safety management system on a regular basis. The x-ray tube voltage (kVp), which is directly involved in the patient exposure dose and the life of the equipment, needs periodic performance for the quality control, but it has a limitation due to the time and the cost. In this study, we proposed a new method for measuring the kVp with ease by using the Y and Cu to solve the problem of the time and cost. We also evaluated the usefulness and the effectiveness of the new method and its accuracy through the kVp measurement. After securing the condition, the amount of the tube current and evaluating the usefulness and effectiveness of kVp measured using Y and Cu. The density range used was at 0.5-1.0, kVp was in the range of ${\pm}10%$, then, we recorded the change in concentration as % of Y and Cu. This experiment showed that when Cu and Y was at 75 kVp, concentration was the same, and when the kVp was changed to 65 ~ 85 %, a gradual increase in concentration to 85 ~ 110 % was noted.