• International Journal of Aeronautical and Space Sciences
• /
• v.5 no.2
• /
• pp.28-34
• /
• 2004

One of the major problem encountered in nuclear plants and satellites design isEMI (Electro-Magnetic Interference) and EMC (Electro-Magnetic Compatibility).Here, our focus is to implement the test board for checking SEU (Single EventUpsets); the effects of protons on the electronic system. The SEU results from thelevel change of stored information due to photon radiation and temperature in thespace environment. The impact of SEU on PLD (Programmable Logic Devices)technology is most apparent in ROM/SRAM/DRAM devices wherein the state ofstorage cell can be upset. In this paper, a simple and powerful test techniques issuggested, and the results are presented for the analysis and future reference. In ourexperiment, the proton radiation facilitv (having the energy of 50 MeV with a beamcurrent of 60 uA of cyclotron) available at KIRAMS (Korea Institute of RadiologicalMedical Sciences) has been applied on a commercially available SRAM manufacturedby Hynix Semiconductor Company.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.2
• /
• pp.417-422
• /
• 2010

When memory devices are exposed to space environments, they suffer various effects such as SEU(Single Event Upset). Memory systems for space applications are generally equipped with error detection and correction(EDAC) logics against SEUs. In this paper, several error detection and correction codes - RS(10,8) code, (7,4) Hamming code and (16,8) code - are analyzed and compared with each other. Each code is implemented using VHDL and its performances(encoding/decoding speed, required memory size) are compared. Also the failure probability equation of each EDAC code is derived, and the probability value is analyzed for various occurrence rates of SEUs which the STSAT-3 possibly suffers. Finally, the EDAC algorithm for STSAT-3 is determined based on the comparison results.

• Journal of Astronomy and Space Sciences
• /
• v.22 no.4
• /
• pp.537-558
• /
• 2005

This paper addresses the results of HAUSAT-2 radiation environment and effect analyses, including TID and SEE analyses. Trapped proton and electron, solar proton, galactic cosmic ray models were considered for HAUSAT-2 TID radiation environment analysis. TID was analyzed through total dose-depth curve and the radiation tolerance of TID for HAUSAT-2 components was verified by using DMBP method and sectoring analysis. HAUSAT-2 LET spectrum for heavy ion and proton were also analyzed for SEE investigation. SEE(SEU, SEL) analyses were accomplished for MPC860T2B microprocessor and K6X8008T2B memory. It was estimated that several SEUs may occur without SEL during the HAUSAT-2 mission life(2 years). Software Hamming Code EDAC has been implemented to detect and correct the SEU. In this study, all radiation analyses were conducted by using SPENVIS software.

• Journal of Astronomy and Space Sciences
• /
• v.11 no.1
• /
• pp.131-145
• /
• 1994

The Cosmic Ray Experiment (CRE) is one of the modules flown on board the KITSAT-1 satellite and consistes of two sub-systems: the Total Dose Experiment (TDE) and the Cosmic Particl Experiment(CPE). The purpose of CRE is to characterize the space radiation environment as encountered by an Earth-orbiting spacecraft. KITSAT-1 orbit is dominated by the inner Van Allen radiation belt. This region has a large population of high energy protons which contributes significantly to both long-term and transient radiation effects. The data shows that the inner Van Allen radiation belt is very stable and the solar activity influences the CPE, TDE data and SEU(Single Event Upset) rates. The result also shows that much larger high energy particle flux is recorded than the predictions of the CREME code.

• Journal of Semiconductor Engineering
• /
• v.1 no.3
• /
• pp.81-87
• /
• 2020

An instrumentation amplifier (IA) and an analog-to-digital converter (ADC) are essential circuit blocks for accurate and robust sensor readout systems. This paper introduces recent advances in radiation-hardening by design (RHBD) techniques applied for the sensor readout integrated circuits (IC), e.g., the three-op-amp IA and the successive-approximation register (SAR) ADC, operating against total ionizing dose (TID) and singe event effect (SEE) in harsh radiation environments. The radiation-hardened IA utilized TID monitoring and adaptive reference control to compensate for transistor parameter variations due to radiation effects. The radiation-hardened SAR ADC adopts delay-based double-feedback flip-flops to prevent soft errors which flips the data bits. Radiation-hardened IA and ADC were verified through compact model simulation, and fabricated CMOS chips were measured in radiation facilities to confirm their radiation tolerance.

• Weed & Turfgrass Science
• /
• v.3 no.2
• /
• pp.130-136
• /
• 2014

Tall fescue is commonly well-adapted for low maintain area because of its wear resistance, deep root system, and drought tolerances. Deep and infrequent irrigation refers to applying large amounts of irrigation, 1.3 to 2.5 cm or more, in a single irrigation event. Light and frequent irrigation is commonly used with small amounts of water, 0.3 to 0.6 cm, every day or every other day. N use for turfgrass management is often unnoticed for water management. The objective of this field study was to evaluate the effects of irrigation frequency and N rates for tall fescue growth. The three irrigation treatments were no irrigation (precipitation only), 0.5 cm applied every other day, and 1.8 cm applied once a week at one irrigation event. The nitrogen (N) treatments were the low, medium, and high N rate treatments. The low, medium, and high N treatments were applied over 2, 4, and 6 applications, respectively. If high main maintenance of tall fescue is not important and water source is limited, irrigation is not necessary and, the $9.8gNm^{-2}yr^{-1}$ of two applications can be recommended for tall fescue under the weather condition of the study.

• Journal of Korea Water Resources Association
• /
• v.40 no.2 s.175
• /
• pp.101-112
• /
• 2007

In this study, a methodology was developed to evaluate the effects produced in the event of joint-operation of dams from the viewpoint of water use. It was applied to evaluating the actual results of dam operation in the Han River basin. In order to evaluate the effects of real joint-operation in terms of water supply and flow conditions, the methodology used the satisfaction rate of water requirement and the stability of flow conditions at the evaluation site as indicator. In order to evaluate the effects of joint-operation in terms of power generation, the total power generation produced by dams was used as evaluation indicator. Actual operation results were evaluated by comparison of evaluation indicators relating to single dam operation by which the notified mont of water was supplied, as well as to optimization models. Results of actual joint-operation of the Han River basin, from 2001 to 2004, were compared yearly with results from single operation and optimization model; in terms of water supply, the satisfaction ratio of water requirement stood at $94.36{\sim}99.68%$ for single operation, $97.16{\sim}99.90%$ for actual joint-operation, and 100.0 % for optimization model for all four years. The stability of flow condition was evaluated by the coefficient of river regime and coefficient of flow conditions definitely, indicating that flow conditions were more stable in case of actual operation and optimization models than in case of single operation. The actual total power generation was compared with that generated by other operation rules, indicating that the optimization model increased the power generation by $-3.47{\sim}6.54%$ compared with the actual total power generation, and that the single operation decreased the power generation amount by $12.68{\sim}38.94%$ compared with the actual total power generation.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.4
• /
• pp.35-41
• /
• 2008

When memory devices are exposed to a space environment. they suffer various effects such as SEU(Single Event Upset). For these reasons, memory systems for space applications are generally equipped with error detection and correction(EDAC) logics against SEUs. In this paper, the error detection and correction strategy in the Mass Memory Unit(MMU) of the STSAT-3 is discussed. The probability equation of un-recoverable SEUs in the mass memory system is derived when the whole memory is encoded and decoded by the RS(10,8) Reed-Solomon code. Also the probability value is analyzed for various occurrence rates of SEUs which the STSAT-3 possibly suffers. The analyzed results can be used to determine the period of scrubbing the whole memory, which is one of the important parameters in the design of the MMU.

• The Korea Journal of Herbology
• /
• v.36 no.5
• /
• pp.69-79
• /
• 2021

Objectives : In clinical practice, there are many cases of co-administration of herbal medicine and synthetic drugs. This study tried to identify whether the combined administration of herbal medicine and synthetic drugs including amoxicillin increases Helcicobacter pylori eradication rate compared to the single administration of synthetic drugs or the combined administration of synthetic drugs and placebo herbal medicine through systematic review. Methods : Relevant randomized controlled trials were searched in PubMED database. The risk of biases was assessed through the Cochrane Risk of Bias criteria. Three reviewers were extracted the characteristics and outcomes of each study. Meta-analysis of eradication rate and adverse event was conducted. Results : Four RCTs were selected. In meta-analysis, the combination of herbal medicine and synthetic drugs showed eradication effect, but it was not statistically significant (Odds Ratio [OR] 0.46; 95% confidence interval [CI] 0.17 to 1.24; p=0.13; I²=56%) than administration of synthetic medicine alone. Combination of herbal medicine and synthetic medicine did not increased the incidence of adverse event(OR 1.07; 95% CI 0.72 to 1.59; p=0.68, I²=0%) compared to single administration of synthetic medicine. Conclusion : Although no significant difference was observed between the two groups in the eradication rate and the incidence rate of adverse events, it was difficult to draw a clear conclusion due to the heterogeneity between studies and the low quality of reporting. A number of studies that have overcome these limitations in the future will lead to definite conclusions.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4422-4430
• /
• 2022

Studying the effects of gamma radiation on the instrumentation and control (I&C) system of a nuclear power plant is critical to the successful and reliable operation of the plant. In the accidental scenario, the adverse environment of ionizing radiation affects the performance of the I&C system and it leads to inaccurate and incomprehensible results. This paper reports the effects of gamma radiation on the AT89C51RD2, a commercial-off-the-shelf 8-bit high-performance flash microcontroller. The microcontroller, selected for the device under test for this study is used in the remote terminal unit for a nuclear power plant. The custom circuits were made to test the microcontroller under different gamma doses using a ⁶⁰Co gamma source in both ex-situ and in-situ modes. The device was exposed to a maximum dose of 1.5 kGy. Under this hostile environment, the performance of the microcontroller was studied in terms of device current and voltage changes. It was observed that the microcontroller device can operate up to a total absorbed dose of approximately 0.6 kGy without any failure or degradation in its performance.