• Nuclear Engineering and Technology
• /
• v.52 no.8
• /
• pp.1626-1637
• /
• 2020

This work covers an important point of the benchmark released by the expert group on Uncertainty Analysis in Modeling of Light Water Reactors. This ambitious benchmark aims to determine the uncertainty in light water reactors systems and processes in all stages of calculation, with emphasis on multi-physics (coupled) and multi-scale simulations. The Gesellschaft für Anlagen und Reaktorsicherheit methodology is used to propagate the thermal-hydraulic uncertainty of macroscopic parameters through TRACE5.0p3/PARCSv3.0 coupled code. The main innovative points achieved in this work are i) a new thermal-hydraulic model is developed with a highly-accurate 3D core discretization plus an iterative process is presented to adjust the 3D bypass flow, ii) a control rod insertion occurrence -which data is obtained from a real PWR test- is used as a transient simulation, iii) two approaches are used for the propagation process: maximum response where the uncertainty and sensitivity analysis is performed for the maximum absolute response and index dependent where the uncertainty and sensitivity analysis is performed at each time step, and iv) RESTING MATLAB code is developed to automate the model generation process and, then, propagate the thermal-hydraulic uncertainty. The input uncertainty information is found in related literature or, if not found, defined based on expert judgment. This paper, first, presents the Gesellschaft für Anlagen und Reaktorsicherheit methodology to propagate the uncertainty in thermal-hydraulic macroscopic parameters and, then, shows the results when the methodology is applied to a PWR reactor.

• Korean Chemical Engineering Research
• /
• v.56 no.3
• /
• pp.388-403
• /
• 2018

We investigated design requirements of vent lines for Sodium-Water Reaction Pressure Relief System of Prototype Generation-IV Sodium-Cooled Fast Reactor. We developed design requirements of areas of the rupture disks of the steam generator, a diameter of the gas vent line of the sodium dump tank, a diameter of the gas vent line of the water dump tank, a diameter of the water dump line of the steam generator. With the design requirements, we calculated the time to vent fluid inside the steam generator and analyzed the transient pressure behavior, also evaluated the close pressure value of the isolation valve of the water dump line. Our results are expected to be used as basis information to design Sodium-Water Reaction Pressure Relief System of Prototype Generation IV Sodium-Cooled Fast Reactor.

• Journal of Communications and Networks
• /
• v.11 no.6
• /
• pp.544-555
• /
• 2009

This work continues a trend of developments aimed at exploiting the physical layer of the open systems interconnection (OSI) model to enhance wireless network security. The goal is to augment activity occurring across other OSI layers and provide improved safeguards against unauthorized access. Relative to intrusion detection and anti-spoofing, this paper provides details for a proof-of-concept investigation involving "air monitor" applications where physical equipment constraints are not overly restrictive. In this case, RF fingerprinting is emerging as a viable security measure for providing device-specific identification (manufacturer, model, and/or serial number). RF fingerprint features can be extracted from various regions of collected bursts, the detection of which has been extensively researched. Given reliable burst detection, the near-term challenge is to find robust fingerprint features to improve device distinguishability. This is addressed here using wavelet domain (WD) RF fingerprinting based on dual-tree complex wavelet transform (DT-$\mathbb{C}WT$) features extracted from the non-transient preamble response of OFDM-based 802.11a signals. Intra-manufacturer classification performance is evaluated using four like-model Cisco devices with dissimilar serial numbers. WD fingerprinting effectiveness is demonstrated using Fisher-based multiple discriminant analysis (MDA) with maximum likelihood (ML) classification. The effects of varying channel SNR, burst detection error and dissimilar SNRs for MDA/ML training and classification are considered. Relative to time domain (TD) RF fingerprinting, WD fingerprinting with DT-$\mathbb{C}WT$ features emerged as the superior alternative for all scenarios at SNRs below 20 dB while achieving performance gains of up to 8 dB at 80% classification accuracy.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.7
• /
• pp.1-8
• /
• 2008

We fabricated flexible electrophoretic display(EPD) driven by organic thin film transistors(OTFTs) on plastic substrate. We designed the W/L of OTFT to be 15, considering EPD's transient characteristics. The OTFTs employed bottom contact structure and used Al for gate electrode, the cross-linked polyvinylphenol for gate insulator, pentacene for active layer. The plastic substrate was coated by PVP barrier layer in order to remove the islands which were formed after pre-shrinkage process and caused the electrical short between bottom scan and top data metal lines. Pentacene active layer was confined within the gate electrodes so that the off current was controlled and reduced by gate electrodes. Especially, PVA/Acryl double layers were inserted between EPD panel and OTFT-backplane in order to protect OTFT-backplane from the damages created by lamination process of EPD panel on the backplane and also accommodate pixel electrodes through via holes. From the OTFT-backplane the mobility was $0.21cm^2/V.s$, Ion/Ioff current ratio $10^5$. The OTFT-EPD panel worked successfully and demonstrated to display some patterns.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.34C no.11
• /
• pp.1-11
• /
• 1997

The transient current components of the dRAM are analyzed and the sensing current, data path operation current and DC leakage current are revealed to be the major curretn components. It is expected that the supply voltage of less than 1.5V with low VT MOS witll be used in multi-giga bit dRAM. A low voltage dual VT self-timed CMOS logic in which the subthreshold leakage current path is blocked by a large high-VT MOS is proposed. An active signal at each node of the nature speeds up the signal propagation and enables the synchronous DRAM to adopt a fast pipelining scheme. The sensing current can be reduced by adopting 8 bit prefetch scheme with 1.2V VDD. Although the total cycle time for the sequential 8 bit read is the same as that of the 3.3V conventional DRAM, the sensing current is loered to 0.7mA or less than 2.3% of the current of 3.3V conventional DRAM. 4 stage pipeline scheme is used to rduce the power consumption in the 4 giga bit DRAM data path of which length and RC delay amount to 3 cm and 23.3ns, respectively. A simple wave pipeline scheme is used in the data path where 4 sequential data pulses of 5 ns width are concurrently transferred. With the reduction of the supply voltage from 3.3V to 1.2V, the operation current is lowered from 22mA to 2.5mA while the operation speed is enhanced more than 4 times with 6 ns cycle time.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.6
• /
• pp.91-98
• /
• 2004

This paper proposes a PCB plane model for generic SPICE circuit simulators. The proposed model reflects two frequency-dependent losses, namely skin and dielectric losses. After power/ground plane pair is divided into arrays of unit-cells, each unit-cell is modeled using a transmission line and two loss models. The loss model is composed of a resistor for DC loss, series HL ladder circuit for skin loss and series RC ladder circuit for dielectric loss. To verify the validity of the proposed model, it is compared with SPICE ac analysis using frequency-dependent resistors. Also, we show that the estimation results using the proposed model have a good correlation with that of VNA measurement for the typical PCB stack-up structure of general desktop PCs. With the proposed model, not only ac analysis but also transient analysis can be easily done for circuits including various non-linear/linear devices since the model consists of passive elements onl.

• Korean Journal of Biological Psychiatry
• /
• v.13 no.2
• /
• pp.103-109
• /
• 2006

Objective : Associations of vascular risk/disease or apolipoprotein E ${\varepsilon}4$(APOE4) with geriatric depression has been unclear at a population level. This study aimed to evaluate whether there would be interactions of vascular risk/disease and APOE4 on depression in a Korean elderly population. Methods : 732 community residents aged 65 or over were assessed for depression(GMS), information on vascular risk/disease(reported stroke, transient ishemic attack, heart disease, hypertension, diabetes, smoking), examinations for vascular risk/disease(blood pressure, blood tests for glucose and lipid profiles, body size), APOE genotypes, demographic characteristics(age, gender, education), physical health, and cognitive function(MMSE). Results : Previous stroke and lower level of high density lipoprotein(HDL) cholesterol were significantly associated with geriatric depression independent of demographic characteristics, physical illnesses, and cognitive function. These associations were statistically significant only in those with APOE4, although the interaction terms didn't reach to statistical significance. Conclusion : Associations between vascular risk/disease and geriatric depression might be more prominent in those with APOE4. However further research would be needed to clarify this issue.

• The Journal of Internal Korean Medicine
• /
• v.37 no.1
• /
• pp.8-15
• /
• 2016

Objectives: To provide information on the safety of GST (Gami-Sasangja-tang), we carried out a single oral dose-increasing toxicity test of GST in beagle dogs.Materials and Methods: Six beagle dogs (three males and three females) were randomly assigned to two groups (experimental group: n=4, control group: n=2). The experimental group (two males, two females) was given oral doses of GST in increasing order (1,250, 2,500, and 5,000 mg/kg) at three-day intervals. After administration, the participants’ mortality, clinical signs, and body weight changes were monitored for two weeks. After two weeks, all dogs were sacrificed for autopsy.Results: Temporary vomiting was observed according to increasing dosage (n=1, 250 mg/kg; n=4, 2,500 and 5,000 mg/kg). Transient diarrhea was observed on the second and third dosing day (n=1, 2,500 mg/kg; n=2, 5,000 mg/kg). Temporary salivation was noted on the third dosing day (n=3, 5,000 mg/kg). Compound-colored stool was observed in all dogs fed the GST on all dosing days and also on the following days. We found no mortality and no abnormalities in the clinical signs, body weight, and gross findings in any of the dogs tested.Conclusions: The maximum tolerated dose was over 5,000 mg/kg for both male and female dogs.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.3
• /
• pp.150-157
• /
• 2002

A nonlinear shaping method for a wire antenna is presented to improve the limited pulse radiation ability due to the frequency characteristics with nulls which are found in the conventional straight or V antennas. The developed scheme is based on the minimization of frequency-dependence of the radiated electric field intensity over wide band, hence giving the ripple-type frequency characteristics. It is shown that the synthesized shape has more advantage in the case of shorter pulse. That is, we found that for shorter pulse exciting, the radiated peak value of the synthesized antenna is larger than that of the conventional linear antenna. The inverse discrete Fourier transform based on the moment method is used for the transient analysis of current distribution and far field electric field.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.37 no.5
• /
• pp.11-116
• /
• 2000

A topology decreased switching loss and voltage stress by zero voltage switching is presented in this paper. Generally, Switching mode converting productes voltage stress and power losses due to excessive voltage and current. which affect to performance of power supply and reduce overall efficiency of equipments. Virtually, In flyback converter, transient peak voltage and current at switcher are generated by parasitic elements. To solve these problems, present ZVS flyback converter topology applied a auxiliary circuit. Incorporation of auxiliary circuit into a conventional flyback topology serves to reduce power losses and to minimize switching voltage stress. Snubber capacitor in auxiliary circuit serves ZVS state by control voltage variable time at turn on and off of main switch, then reduces voltage stress and power losses. The proposed converter has lossless switching in variable load condition with wide range. A detailed analysis of the circuit is presented and the operation procedure is illustrated. A (50W 100kHz prototype) ZVS flyback converter using a auxiliary circuit is built which shows an efficiency improvement as compared to a conventional hard switching flyback converter.