• Nuclear Engineering and Technology
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• 제56권1호
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• pp.257-264
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• 2024

The sodium cooled fast reactor (SFR) is one of the Gen-IV reactors with the most operating experience accumulated. Although the technology level is the most mature among the Gen-IV reactors, there is still a safety problem that has not been solved, which is the sodium-water reaction. Since sodium and water are separated only by a heat transfer tube with a thickness of only a few mm, there is inherently a risk of a sodium-water reaction (SWR) accident in the SFR. In this study, it is attempted to quantitatively evaluate the resistance of SWR accidents by replacing the shell and tube steam generator with printed circuit steam generator (PCSG) as a method to mitigate the SWR accident. To do this, a CATS-S (Compact Accident Tolerance Steam Generator-SWR) facility was designed and built. And for the quantitative evaluation of accident resistance, a methodology for measuring the impingement wastage rate was established. As a result of this research, the impingement wastage rate caused by SWR generated in a PCSG was measured first time. It was confirmed that the impingement wastage phenomenon was suppressed in the PCSG, and the accident resistance was higher than that of the SWR through comparison with the experimental results performed in the existing shell and tube steam generator. In conclusion, a PCSG is more resistant to impingement wastage as a result of the SWR accident than existing shell and tube steam generators, and it is estimated that a PCSG can mitigate SWR accidents, an inherent problem of SFR.

• 물과 미래
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• 제25권2호
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• pp.79-87
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• 1992

본 연구는 굴곡도(sinuosity)가 작은 정현파형(SWR)하천에서 사행 이행의 크기와 방향 및 제방부근의 하상세굴 위치와 크기를 예측할 수 있는 이행특성 모형을 운동량 방정식, 질량보존법칙, 하상 안정식을 적용하여 개발하였다. 본연구에서 황방향 하상계수 B'와 질량 이송계수 a 는 SWR 하천에서 중요한 역할을 하는 변수임이 확인되었으며, 그 값은 각각 B'는 4.0, a는 0.40이 합리적인 값으로 나타났다. 본 모형은 SWR 하천 유역의 개발계획 및 설계시 유용한 정보를 제공해 줄 것이다.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.94-101
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• 2007

This paper, we analyzed that the measured data of the radiated power spectrum of electromagnetic waves and the standing wave ratio(SWR) of the spark plug cable and spark plug. The measured data are the power strength of the electromagnetic waves radiated from the spark ignition system, the measured frequency ranges are 110 to 610MHz. The results show that the strength of radiated power spectrum and bandwidth have relation to the SWR of the the spark plug cable and spark plug, and the SWR of them is different because of the characteristics of resistor at the spark plug is different with the manufacturers. From the analyzed results, it can be concluded that the less SWR is little, the less maximum level of power spectrum is weak and bandwidth above the reference level is small.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1338-1348
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• 2016

A novel fully passive small modular superheated water reactor (SWR) for underwater deployment is designed to produce 160 MWe with steam at $500^{\circ}C$ to increase the thermodynamic efficiency compared with standard light water reactors. The SWR design is based on a conceptual 400-MWe integral SWR using the internally and externally cooled annular fuel (IXAF). The coolant boils in the external channels throughout the core to approximately the same quality as a conventional boiling water reactor and then the steam, instead of exiting the reactor pressure vessel, turns around and flows downward in the central channel of some IXAF fuel rods within each assembly and then flows upward through the rest of the IXAF pins in the assembly and exits the reactor pressure vessel as superheated steam. In this study, new cladding material to withstand high temperature steam in addition to the fuel mechanical and safety behavior is investigated. The steam temperature was found to depend on the thermal and mechanical characteristics of the fuel. The SWR showed a very different transient behavior compared with a boiling water reactor. The inter-play between the inner and outer channels of the IXAF was mainly beneficial except in the case of sudden reactivity insertion transients where additional control consideration is required.

• Applied Microscopy
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• 제52권
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• pp.1.1-1.8
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• 2022

As semiconductor device architecture develops, from planar field-effect transistors (FET) to FinFET and gate-all-around (GAA), there is an increased need to measure 3D structure sidewalls precisely. Here, we present a 3-Dimensional Atomic Force Microscope (3D-AFM), a powerful 3D metrology tool to measure the sidewall roughness (SWR) of vertical and undercut structures. First, we measured three different dies repeatedly to calculate reproducibility in die level. Reproducible results were derived with a relative standard deviation under 2%. Second, we measured 13 different dies, including the center and edge of the wafer, to analyze SWR distribution in wafer level and reliable results were measured. All analysis was performed using a novel algorithm, including auto fattening, sidewall detection, and SWR calculation. In addition, SWR automatic analysis software was implemented to reduce analysis time and to provide standard analysis. The results suggest that our 3D-AFM, based on the tilted Z scanner, will enable an advanced methodology for automated 3D measurement and analysis.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1991년도 봄 학술발표회 논문집
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• pp.75-80
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• 1991

Results of an experimental investigation of low-rise reinforced concrete shear walls with rectangular cross section under cyclic loads are discussed and evaluated. Two half scale models of test specimens with height to length ratio of 0.75 were experimented. The dimension of all walls is 1500mm wide $\times$ 950 mm high $\times$ 100 mm thick for all specimens and the section of all boundary at both ends is 100 mm $\times$ 200mm. Main variables are : horizontal shear reinforcement ratios and reinforcement details(including crossed diagonal shear reinforcements in SWR2 specimen) In SWR2 specimen, maximum strength and consequently dissipating energy index were 1.15~1.21 and 1.48 times greater than those of SWR1 specimen, respectively.

• Nuclear Engineering and Technology
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• 제35권6호
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• pp.566-580
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• 2003

To resolve the concern of the SWR possibility in LMR and improve the economic feature of LMR, relative performance of various SG designs using a double tube bundle configuration is evaluated and a new SG design concept is proposed. The new steam generator design houses two tube bundles that are functionally different and its tube bundle region is radially divided into two. It prevents the occurrence of sodium water reaction while sodium is still used as the coolant for the primary heat transport system. The feasibility of the SG with a double tube bundle for actual use in an LMR plant is evaluated by setting up the skeleton of the NSSS for various possible configurations of the SG tube bundles. The evaluation revealed the relative advantages and disadvantages of the configurations and the new SG design concept performs good and can be actually used in an LMR plant.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.190-195
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• 2003

We developed a loading sleeve for Automobile, which has the PCS and IMT-2000 frequency bands. The electric characteristics of the designed sleeve monopole has SWR<1.311 and 3.0dBi in average gain for that frequency bands. In this study, the designed sleeve monopole was installed at a roof and trunk lid of vehicle. The characteristics of designed sleeve monopole was investigated by measuring SWR, input impedance and radiation pattern. The experimental results show that the efficiency of the sleeve monopole is superior th that of domestic and foreign commercial PCS antenna.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.385-390
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• 2006

This paper examines the sampling and jitter specifications and considerations for Global Navigation Satellite Systems (GNSS) software receivers. Software radio (SWR) technologies are being used in the implementation of communication receivers in general and GNSS receivers in particular. With the advent of new GPS signals, and a range of new Galileo and GLONASS signals soon becoming available, GNSS is an application where SWR and software-defined radio (SDR) are likely to have an impact. The sampling process is critical for SWR receivers, where it occurs as close to the antenna as possible. One way to achieve this is by BandPass Sampling (BPS), which is an undersampling technique that exploits aliasing to perform downconversion. BPS enables removal of the IF stage in the radio receiver. The sampling frequency is a very important factor since it influences both receiver performance and implementation efficiency. However, the design of BPS can result in degradation of Signal-to-Noise Ratio (SNR) due to the out-of-band noise being aliased. Important to the specification of both the ADC and its clocking Phase- Locked Loop (PLL) is jitter. Contributing to the system jitter are the aperture jitter of the sample-and-hold switch at the input of ADC and the sampling-clock jitter. Aperture jitter effects have usually been modeled as additive noise, based on a sinusoidal input signal, and limits the achievable Signal-to-Noise Ratio (SNR). Jitter in the sampled signal has several sources: phase noise in the Voltage-Controlled Oscillator (VCO) within the sampling PLL, jitter introduced by variations in the period of the frequency divider used in the sampling PLL and cross-talk from the lock line running parallel to signal lines. Jitter in the sampling process directly acts to degrade the noise floor and selectivity of receiver. Choosing an appropriate VCO for a SWR system is not as simple as finding one with right oscillator frequency. Similarly, it is important to specify the right jitter performance for the ADC. In this paper, the allowable sampling frequencies are calculated and analyzed for the multiple frequency BPS software radio GNSS receivers. The SNR degradation due to jitter in a BPSK system is calculated and required jitter standard deviation allowable for each GNSS band of interest is evaluated. Furthermore, in this paper we have investigated the sources of jitter and a basic jitter budget is calculated that could assist in the design of multiple frequency SWR GNSS receivers. We examine different ADCs and PLLs available in the market and compare known performance with the calculated budget. The results obtained are therefore directly applicable to SWR GNSS receiver design.

• 한국자기학회지
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• 제24권6호
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• pp.165-170
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• 2014

본 연구에서는 두께가 다른 비정질 CoFeB 박막 재료에서 측정한 강자성 및 스핀파 공명 신호를 비교 분석하였다. 강자성 공명 자기장($H_{FMR}$)은 두께에 거의 무관하게 일정한 값을 갖는 반면 스핀파 공명 자기장($H_{SWR}$)은 CoFeB의 두께에 의존하는 스핀파 모드들에 대한 이론 값과 일치하였다. 수평면에서 자기장 각도에 따른 $H_{FMR}$ 측정 결과로부터 CoFeB 재료의 일축이방성 자기장은 37 Oe였다. 한편 $H_{SWR}$은 $H_{FMR}$과 동일한 각도 의존성을 보였으며, 스핀파 공명 신호의 크기는 강자성 공명 신호에 비하여 약 5.7배 증가하였다. 이러한 증가는 비정질 재료의 작은 감쇠 상수에 의한 저감이 작은 스핀파의 진행 특성 및 균일한 자화에 의한 이상적인 정상파 형성 조건에 기인함을 알 수 있었다.