• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.925-932
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• 2009

Precise temperature monitoring is the major preconditioning to supervise quality losses within the transport chain for fresh products. ISO/IEC18000-6REV1 defines new protocols supporting BAP(Battery Assisted Passive) RFID tag which is completely compatible with EPCglobal Class1 Generation2 specification. In this paper, we designed a modem supporting BAP RFID tag with FPGA(Field Programmable Gate Array) and implemented sensor data processing function defined in ISO/IEC18000-6REV1. The transmit block of the modem supports pulse shaping filter and the output signal of the implemented RFID reader is satisfied with the spectrum mask defined in the standard. The receive block of the modem uses Gardner TED to synchronize timing of symbol. In this paper, we designed a modem supporting ISO/IEC18000-6REV1 standard and developed a RFID reader sndard. The developed RFID reader sndard can recognize sensor tag and passive tag in the wireless environment and supports real-time processing of the sensor data in the embedded linux platform.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.3
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• pp.159-166
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• 2018

Herein, a non-Foster matching circuit is designed to improve the impedance matching characteristics of small antennas in the VHF and UHF bands. The proposed non-Foster circuit is designed to operate with negative capacitance in a wide frequency band from 50 MHz to 1,000 MHz for use in various communication bands. To ensure the stability of the non-Foster circuit with conditional stability, the open-circuit stability condition of Linvill was satisfied, and the circuit was fabricated using the FR-4 substrate. The fabricated non-Foster circuit was combined with a small antenna to verify its performance by measuring the return loss and received power in the FM, DMB, and GSM bands. The measured return loss was improved from -6 dB to -30 dB, and the measured received power was improved from 0.5 dBm to 5.2 dBm.

• Journal of Environmental Science International
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• v.15 no.12
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• pp.1093-1101
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• 2006

In the present study we studied the growth, photosynthetic traits and protective mechanisms against oxidative stress in the primary loaves of cucumber (Cucumis sativus L.) seedlings with or without UV-B treatment. Cucumber seedings were irradiated with UV-B for 10 days in environment-controlled growth chambers. The primary leaves irradiated with UV-B showed reduction in leaf length and decreased biomass production. The reduced biomass production seemed to be due to a negative effect of UV-B radiation on the photosynthetic process. Changes in chemical properties of leaf, such as chi a/b ratio affected photosynthesis. UV-B significantly affected chl b content compared with chi a in the light harvesting complex resulting reduced photosynthetic activity Fv/Fm decreased with an UV-B stress, suggesting that the photosynthetic apparatus, and particularly, PS II was damaged under UV-B stress. Malondialdehyde(MDA) concentration which represents the state of membrane lipid peroxidation Increased significantly under UV-B stress confirming an oxidative stress. UV-B exposure with SA solution(0.1-1.0 mM) can partially ameliorated some of the detrimental effects of UV-B stress. Leaf injuries including loss of chlorophyll and decreased ratio of Fv/Fm were reduced with combined application of UV-B and SA. ABA and JA showed similar mode of action in physiological effects on photosynthetic activities though the levels were lower than those from SA treated plants. Chloroplast ultrastructure was also affected by UV-B exposure. The thickness of leaf tissue components decreased and the number of grana and thylakoids was reduced in chloroplast applied UV-B or SA alone. At combined stress granal and stromal thylakoids were less affected. The leaves under combined stress acquired a significant tolerance to oxidative stress. From these results, it can be suggested that SA may have involved a protective role against UV-B induced oxidative damage.

• Fire Science and Engineering
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• v.30 no.2
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• pp.43-48
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• 2016

One of the main problems with gaseous fire extinguishers is the decrease in fire suppression capability due to the leakage of the fire extinguishing agents, either naturally or caused by obsolete equipment. Therefore, in this study, a real-time detector module for monitoring pressure leakages was developed and an assessment on its performance was carried out. Currently, there are no domestic or global standards for testing pressure leakage detection systems. Therefore, similar global standards, such as ISO 7240 and FM 1421, and the domestic law on "Receiver type-approval and technical standards for product inspection" were used as a reference for assessing the performance of the newly developed module. Its basic performance was assessed by applying compressed air to the module, and, as a result, the minimum working pressure was identified as 0.3 bar. Its environmental qualification was carried out to confirm the proper functioning of the module in different climates and the module was confirmed to function properly at both high ($50^{\circ}C$) and low ($-10^{\circ}C$) temperatures.

• Journal of Technologic Dentistry
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• v.39 no.2
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• pp.83-91
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• 2017

Purpose: The objective of this study was to evaluate influence of mechanical properties of gingival shade composite resins(GSCRs) according to thermocycling treatment. Methods: The material utilized in this study was Crea.lign(CGR), Twiny flow(TGF) and Twiny(TGP). Total sixty specimens were fabricated with a dimension of $25{\times}2{\times}2mm$ according to the ISO 4049. After fabrications, specimens of before and after thermocycling(to $55^{\circ}C$ from $5^{\circ}C$) were stored in the distilled water for 24 hours at the $37^{\circ}C$. Three-point flexural test was performed in universal testing machine(Instron 5966, USA) at a crosshead speed of 1 mm/min. Flexural strength, flexural modulus and work of fracture according to the thermocycling were analyzed using a one-way ANOVA analysis. Surface analysis of GSCRs after thermocycling evaluated using the scanning electron microscope. Results: : The highest FS was measured in TGP group of NTC group and lowest in CGR group after TC. After TC, FS and FM decreased in CGR and TGP groups, but TGF increased. There was a statistically significant difference between FS and WOF in GSCRs(p<0.05). But FM did not show any significant difference after TC (p>0.05). The strength of the characteristic exceeded the flexural strength required by ISO 4049(> 80 MPa). Weibull modulus(m) showed the highest reliability in the TGP group (m = 14.22), and the reliability of the TGF and TGP groups after TC decreased. Conclusion: Thermocycling treatment is important factor influence of mechanical properties with gingival shade composite resins. Therefore, we recommended that mechanical properties need to get useful information and accuracy for life-span expectancy according to the thermocycling treatment.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.40.2-40.2
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• 2010

MIRIS 우주관측카메라는 과학기술위성 3호의 주탑재체로서 $0.8{\sim}2.0{\mu}m$의 근적외선영역에서 우주배경복사와 우리은하 평면의 Pa-$\alpha$ survey 관측을 목적으로 한다. 이러한 임무를 수행하기 위해 MIRIS 우주관측카메라에는 MCT(HgCdTe) IR 검출기가 사용되고 6개의 필터를 장착할 수 있는 필터휠이 설계되었으며, 열잡음을 줄이고 원하는 SNR을 얻기 위해 모두 100K 이하로 냉각이 요구된다. 효과적인 냉각 및 저온유지를 위해서 외부의 열을 1차적으로 차단하는 Cryostat 외부용기와 100K 이하로 냉각되는 내부 Cold Box의 이중구조를 가지는 Dewar가 설계 되었다. 내부 Cold Box의 냉각은 소형 stirling cooler로 이루어지고 외부의 열 유입량이 Cooler의 냉각용량을 넘지 않도록 설계하였다. Cryostat 외부용기는 radiation cooling으로 냉각되어 200K 이하의 온도를 유지하며 내부 Cold Box로의 열유입을 최소화하기 위해 GFRP(Glass Fiber Reinforced Plastic) 단열 지지대와 MLI(Multi Layer Insulation)가 사용된다. 또한 100K으로 냉각시 필터고정부와 Cold Box 구조에서 일어날 수 있는 구조적인 피로도를 줄이고 열변형에 의한 문제를 방지하기 위한 고려가 설계에 포함되었다. FM(Flight Model)은 고진공 환경의 우주공간에서 문제가 발생하지 않도록 설계되었다. 또한 EQM 진동시험결과를 토대로 발사환경에서 발생하는 강한 진동을 견딜 수 있도록 FEM(Finite Elements Method) 구조해석을 통하여 필터고정부에 flexible structure 설계와 완충제를 추가하고 필터휠 구동부와 harness 고정부 및 cooler 지지부를 비롯한 전체 구조물에서 충분히 진동을 극복할 수 있도록 설계하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.11
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• pp.12-17
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• 2009

This paper presents a tag emulator for a UHF band RFID system. The tag emulator supports the 1800-6C and EPC global class 1 generation 2 standards. The transmitted signal from a reader is generated using the PIE coding and ASK modulation methods. Signals of a tag are from the FM0 coding and ASK modulation methods. The ARM7 processor carries out the overall control of the system and signal analysis of incoming data. The verification of the tag emulator employs the application platform implemented in C++. Users can define parameter values for protocol during the application run. The tag emulator presented in this paper allows evaluating various design alternatives of the target RFID system in real applications.

• Journal of Digital Contents Society
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• v.7 no.3
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• pp.147-151
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• 2006

In recent years, the Internation Standard ISO/IEC 18000-6 is announced and a new scheme of Type C is added to conventional standard. Among the RFID systems the ISO/IEC 18000-6 standard is the most interesting to companies due to its potential market growth. The operating frequency is between 860-960 MHz, and three kinds of RFID system are included in the standard, i.e. type A, B and C. In this paper, we implemented the data frame of type C with baseband coding using VHDL. The data frame is encoded based on Miller code and FM0. We showed the implementation results with waveforms. The data frame was proved that it is properly implemented by the experiment of transmission and receiving operation.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.244-251
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• 2015

The paper evaluates the effect of the physical property, fineness modulus (FM) and replacement ratio of crushed sand on the characteristics of concrete. This is intended to use crushed sand from Daegu-Kyungbuk region as the fine aggregate of concrete. The experimental result indicates that the replacement ratio of crushed sand needs to be less than 50% to satisfy the mixed gradation of both natural and crushed sand when their FMs are 2.0 and 3.2, respectively. The slump of concrete with crushed sand increased as the replacement ratio of crushed sand increased, while the workability of concrete with the replacement ratio of more than 75% was significantly reduced. The air content and bleeding rate of concrete was reduced as the replacement ratio increased. Furthermore, due to the enhancement of the concrete adhesive regardless of the FM of crushed sand, compressive strength of concrete tended to improve as the replacement ratio increased.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.199-206
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• 2023

In this paper, the current status of domestic radio use was compared with foreign countries such as the UK and the US. As a result of the comparison, it was found that the radio reach in both the UK and the US was very high at around 90%, but in Korea it was found to be very low at 21.7%. In addition, in the UK and the US, radio broadcasting is recognized as an important medium for delivering disaster warning messages in the event of a disaster, but in Korea, the importance of radio broadcasting in disaster situations was assessed at 0.7%, confirming that its importance is being overlooked. And the measures to increase the domestic radio broadcasting usage rate are 'Improving service quality such as expanding radio reception coverage', 'Awareness of the importance of radio broadcasting as a disaster warning medium', 'Introduction of digital radio' and 'Introduction of FM radio data broadcasting'. are presented.