• Nuclear Engineering and Technology
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• 제51권8호
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• pp.1871-1885
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• 2019

The deterministic MOC code STREAM of the Computational Reactor Physics and Experiment (CORE) laboratory of Ulsan National Institute of Science and Technology (UNIST), was initially designed for the calculation of pressurized water reactor two- and three-dimensional assemblies and cores. Since fast reactors play an important role in the generation-IV concept, it was decided that the code should be upgraded for the analysis of fast neutron spectrum reactors. This paper presents a coupled code - TULIP/STREAM, developed for the fast reactor assembly and core calculations. The TULIP code produces self-shielded multi-group cross-sections using a one-dimensional cylindrical model. The generated cross-section library is used in the STREAM code which solves eigenvalue problems for a two-dimensional assembly and a multi-assembly whole reactor core. Multiplication factors and steady-state power distributions were compared with the reference solutions obtained by the continuous energy Monte-Carlo code MCS. With the developed code, a sensitivity study of the number of energy groups, the order of anisotropic P_N scattering, and the multi-group cross-section generation model was performed on the k_eff and power distribution. The 2D core simulation calculations show that the TULIP/STREAM code gives a k_eff error smaller than 200 pcm and the root mean square errors of the pin-wise power distributions within 2%.

• 한국건강관리협회지
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• 제4권1호
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• pp.28-38
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• 2006

Background : Phentermine classified by "sympathomimmetic amie", is a stimulant of sympatheic tone But there has been no concrete study which presents the influence of phentermine on autonomic nervous system. Analysis of Heart rate variability is reliable, non-invasive and very useful for evaluating function of autonomic nervous system. We tried to elucidate the influence of phentermine on autonomic nervovs system by heart rate variability. MethodsAmong the 70 candidates who participated in the double-blind case control study whichwas designed in purpose of approving whether- Adipekⓓ is effective for treatment of obesity, 45persons were folled up. From April, 2005 to May 2005, HRV of the candidates who takes phentermine or placebo for 1month, was recorded using BFM-5000ⓓ(medi-core) for 5 minutes in resting state. HRV measures were assessed by time-domain and by frequency- domain analysis. Time domain parameters contain SDNN(Standard Deviation of NN intervals) and RMSSD(Root-Mean-Square of Successive Differences), etc and frequency domain Parameters contain Total Power(TP), Low frequency(LF'0.04-0.15Hz) power. High Frequency(HF:0.15-0.4Hz) power and LF/HF ratio etc. Results: Intakes of phentermine reduce HRV significant1y. SDNN & RMSSD, the main tine domain parameters of HRV, were decreased significantly(P=0.007. 0.016). PSI(Physical Stress Index of Pressure Index) was increase significantly(P=0.002)The main frequency domain parameters(TP, LF & VLF), also decreased significantly. (P=0.024,0.033, 0.015)Conclusion: The result showed that intakes of phentermine reduce heart rate variability and influence on most parameters of HRV. So phentermine not only accelerates sympathetic tone, but also inhibit the balance and function of autonomic nervous system.

• 비파괴검사학회지
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• 제29권5호
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• pp.466-472
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• 2009

고온, 고압의 원자력 배관 누설 판별을 위해 음향방출기법(AE)을 이용한 누설감지 시스템인 ALMS 기법이 적용되고 있다. 이 시스템은 단지 AE 센서로 전해진 신호의 RMS값을 이용하여 누설의 유무만을 판단할 뿐, 누설 발생시 누설부의 크기나 형태를 평가하는 것에는 어려움이 있었다. 따라서 본 논문에서는 이러한 문제를 해결하기 위하여 AE센서와 가속도센서를 동시에 이용한 이중 센서 시스템을 제안하였다. 빠른 학습 속도와 정확성을 위해 Levenberg-Marquardt 학습 알고리즘을 이용한 인공신경회로망을 적용시키고, 이를 통해 신뢰성 있는 분석 결과를 얻을 수 있다. 배관내 압력과 누설부의 크기와 모양에 따른 실험신호들을 학습시키고 그 판별 정확성을 확인하였다. 추가적으로 배관 두께에 따라 발생하는 파(wave)의 종류와 특성이 달라지는 것을 이론과 실험을 통하여 알아보았다.

• Current Photovoltaic Research
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• 제11권1호
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• pp.27-33
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• 2023

In this paper, a machine learning model by using a regression algorithm is proposed to estimate the power generation performance of the BIPV system. The physical model formula for estimating the generation performance and the proposed model were compared and analyzed. For the physical model formula, simple efficiency model, temperature correction model, and regressive physics model for changing an irradiance were used. As a result, when comparing the regressive physics model for changing an irradiance and the proposed model with the actual generation measured data, the respective RMSE values are 0.1497 kW, 0.0451 kW and the accuracy values are 86.44%, and 96.56%. Therefore, the proposed model implemented in this experiment can be useful in estimating power generation.

• 한국정보통신학회논문지
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• 제14권8호
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• pp.1901-1906
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• 2010

걸음걸이 패턴 분류는 많은 응용분야가 있을 뿐만 아니라 매우 중요한 연구 분야이다. 따라서 본 연구에서는 허리에 부착된 가속도 모듈로부터 획득된 신호를 이용하여 천천히 걷기(slow walking, S.W), 일반 걷기(normal walking, N.W), 빠르게 걷기(fast walking, F.W) 등의 보행 패턴을 분류하고자한다. 11명의 성인으로부터 블루트스 모듈을 이용하여 100Hz로 샘플링된 3축 가속도 신호를 획득하였다. 획득된 데이터는 웨이브렛 변환을 이용하여 분석하였다. 걸음걸이 패턴은 두가지의 파라미터들을 이용하여 분석되어지는데, 하나는 운동에 해당하는 웨이브렛 계수의 에너지(power)와 전 후방향의 전체 에너지사이의 비율(RPA)이고, 다른 파라미터는 전 후 방향과 상 하 수직 방향 사이에서 웨이브렛 계수의 제곱근 평균 비율(RAV)이다. 천천히 걷기는 다른 걷기와 비교했을 때 작은 RPA값을 가지게 되어 분류가 용이하며, 천천히 걷기는 RAV를 이용하여 일반 걷기와 구별되어 질 수 있었다. 따라서 본연구는 건강한 성인에게서 3축 가속도 신호를 획득한 후 웨이브렛 파라미터를 이용하여 걷기 패턴을 잘 구별할 수 있는 연구임을 확인 하였다.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2107-2119
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• 2022

Accurate remaining useful life (RUL) prediction for critical components of nuclear power equipment is an important way to realize aging management of nuclear power equipment. The electric gate valve is one of the most safety-critical and widely distributed mechanical equipment in nuclear power installations. However, the electric gate valve's extended service in nuclear installations causes aging and degradation induced by crack propagation and leakages. Hence, it is necessary to develop a robust RUL prediction method to evaluate its operating state. Although the particle filter(PF) algorithm and its variants can deal with this nonlinear problem effectively, they suffer from severe particle degeneracy and depletion, which leads to its sub-optimal performance. In this study, we combined the whale algorithm with regularized particle filtering(RPF) to rationalize the particle distribution before resampling, so as to solve the problem of particle degradation, and for valve RUL prediction. The valve's crack propagation is studied using the RPF approach, which takes the Paris Law as a condition function. The crack growth is observed and updated using the root-mean-square (RMS) signal collected from the acoustic emission sensor. At the same time, the proposed method is compared with other optimization algorithms, such as particle swarm optimization algorithm, and verified by the realistic valve aging experimental data. The conclusion shows that the proposed method can effectively predict and analyze the typical valve degradation patterns.

• 산업경영시스템학회지
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• 제28권3호
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• pp.75-86
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• 2005

To investigate the fatigue characteristic of upper limbs, this study analyzed RMS(root mean square) and MPF(mean power frequency) value between initial and terminal stages of each experiment condition. And the effect of intermittent endurance time was evaluated using the Borg's CR10 value that was measured for the parts of upper limb. According to the results of ANOVA on RMS value, there were significant difference on the %MVC about push, pull, and down force exertion. Particularly the ANOVA of up force exertion was significant difference on shoulder flexion, elbow flexion and rest time as well as %MVC. The results of ANOVA for MPF value were significant difference on the %MVC in regard of the push and up force exertion. In case of up force exertion, MPF value tended to shift low frequency at all of the experiment conditions. According to the analysis of duty cycle, RMS value considerably increased over 50% duty cycle and as the %MVC increased, the duty cycle affected the increase of RMS value. MPF value for up and down force exertion decreased at 33%, 50% and 67% duty cycle for all of %MVC. Borg CR10 value of hand and forearm were below the 3-point to the 40% of endurance time at 30%MVC and to the 20% of endurance time at 50%MVC with the exception of up force exertion. But Borg CR10 values of upper arm and shoulder at up force exertion were more than 3-point to the 20% of endurance time at 30%MVC and in the start point of endurance time at 50%MVC.

• 대한한방부인과학회지
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• 제28권3호
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• pp.11-20
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• 2015

Objectives This study is performed to recognize the relationship between atrophic vaginitis and stress that have an affect on autonomic nervous system. Methods We studied 47 patients who visited Kangnam Kyunghee Korean Hospital Medical Examination Center from November, 2013 to June, 2014. They were devided into two groups, atrophic vaginitis group (AV, n=18) and non-atrophic vaginitis group (NAV, n=29). We compared the result of HRV between the two groups. Results The mean of The standard deviation of NN intervals (SDNN), the square root of the mean squared difference of successive NNs (RMSSD) in AV group was lower than NAV group, but there was no significant difference between the two groups. Total power (TP), low frequency (LF) and very low frequency (VLF) of AV group was significantly lower than NAV group. There was no significant difference in high frequency (HF). Conclusions Women with atrophic vaginitis is expected to have low adaptive capacity against stress.

• 대한한방내과학회지
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• 제26권4호
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• pp.844-852
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• 2005

Objectives : Through spectral analysis of heart rate variability(HRV) to study autonomic nervous system dysfunction of Hwabyung, culture related disease in Korea. Methods : HRV of 18 patients diagnosed as Hwabyung was measured against 13 healthy controls. HRV was measured by SA-2000p(Mediocre, Korea) for five minutes after 5 minutes resting. Results : 1. In time domain analysis, mean pulse rate(PRT) of in Hwabyung group was significantly higher than healthy controls. Standard deviation of all normal P-P intervals(SDNN), the square root of the mean of the sum of the squares of differences between adjacent normal P-P intervals(RMS-SD) in Hwabyung group was lower than healthy controls, but not significant. 2. As for frequency domain analysis, In TP(logarithmic total power), In VLF(logarithmic very low frequency), and In LF(logarithmic low frequency )in Hwabyung group was significantly lower than healthy controls. Ln HF(logarithmic high frequency), LF/HF ratio in Hwabyung group was also lower but not significant. Conclusions : This study suggests tile activity and imbalance of cardiac autonomous nervous system in Hwabyung patient is significantly lower than healthy individuals.

• 한국지진공학회논문집
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• 제28권3호
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• pp.121-128
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• 2024

There are growing concerns that the recently implemented Earthquake Early Warning service is overestimating the rapidly provided earthquake magnitudes (M). As a result, the predicted damages unnecessarily activate earthquake protection systems for critical facilities and lifeline infrastructures that are far away. This study is conducted to improve the estimation accuracy of M by incorporating the observed S-wave seismograms in the near source region after removing the site effects of the seismograms in real time by filtering in the time domain. The ensemble of horizontal S-wave spectra from at least five seismograms without site effects is calculated and normalized to a hypocentric target distance (21.54 km) by using the distance attenuation model of Q(f)=348f^0.52 and a cross-over distance of 50 km. The natural logarithmic mean of the S-wave ensemble spectra is then fitted to Brune's source spectrum to obtain the best estimates for M and stress drop (SD) with the fitting weight of 1/standard deviation. The proposed methodology was tested on the 18 recent inland earthquakes in South Korea, and the condition of at least five records for the near-source region is sufficiently fulfilled at an epicentral distance of 30 km. The natural logarithmic standard deviation of the observed S-wave spectra of the ensemble was calculated to be 0.53 using records near the source for 1~10 Hz, compared to 0.42 using whole records. The result shows that the root-mean-square error of M and ln(SD) is approximately 0.17 and 0.6, respectively. This accuracy can provide a confidence interval of 0.4~2.3 of Peak Ground Acceleration values in the distant range.