• 대기
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• 제25권4호
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• pp.659-667
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• 2015

In this study, sensitivity of inflow wind speed and turbulent Schmidt number to pollutant dispersion in an urban street canyon is investigated, by comparing CFD-simulated results to wind-tunnel results. For this, we changed systematically inflow wind speed at the street-canyon height ($1.5{\sim}10.0m\;s^{-1}$ with the increment of $0.5m\;s^{-1}$) and turbulent Schmidt number (0.2~1.3 with interval of 0.1). Also, we performed numerical experiments under the conditions that turbulent Schmidt numbers selected with the magnitude of mean kinetic energy at each grid point were assigned in the street canyon. With the increase of the inflow wind speed, the model underestimated (overestimated) pollutant concentration in the upwind (downwind) side of the street canyon because of the increase of pollutant advection. This implies that, for more realistic reproduction of pollutant dispersion in urban street canyons, large (small) turbulent Schmidt number should be assigned for week (strong) inflow condition. In the cases of selectively assigned turbulent Schmidt number, mean bias remarkably decreased (maximum 60%) compared to the cases of constant turbulent Schmidt number assigned. At week (strong) inflow wind speed, root mean square error decreases as the area where turbulent Schmidt number is selectively assigned becomes large (small).

• Annals of Clinical Neurophysiology
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• 제1권1호
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• pp.31-35
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• 1999

Dignosis of migraine is only based on the medical history, and objective methods to aid the clinical diagnosisare absent. Although transcranial Doppler ultrasonography (TCD) abnormalities in headache-free migraineurs have been reported previously, diagnostic criteria for migraine is still lacking and this may limit the practical application of TCD for migraine. We prospectively studied several abnormal TCD indices in interictal migraineurs and their sensitivity and specificity to define the optimal diagnostic criteria. Young (20 yrs$age=29.0{\pm}6.1yrs$) were compared to 69 controls (M:F=25:44, Mean $age=31.2{\pm}5.5yrs$). Elevated MFV (> 2SD)was observed in 63% of migraineurs while n 12% of control (p<0.01). High AI (>25%) or high HI (>3.0) was present in 17% of migraineurs, while 3% and none in controls (p<0.01). Sensitivity of elevated MFV, high AI, and high HI was 63%, 17%, 17% and specificity was 88%, 97%, 100%, respectively. If all these indices were combined, sensitivity and specificity reached 69% and 86%. These preliminary results suggest pathophysiological implication of vasospasm in interictal migraineurs, and TCD may be practically applicable for migraine. Optimal diagnostic criteria and therapeutic options for patients with abnormal TCD findings remain to bo determined.

• Ocean and Polar Research
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• 제30권2호
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• pp.129-140
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• 2008

As a preliminary effort to establish a data assimilative ocean forecasting system, we reviewed the theory of the Ensemble Kamlan Filter (EnKF) and developed practical techniques to apply the EnKF algorithm in a real ocean circulation modeling system. To verify the performance of the developed EnKF algorithm, a wind-driven double gyre was established in a rectangular ocean using the Regional Ocean Modeling System (ROMS) and the EnKF algorithm was implemented. In the ideal ocean, sea surface temperature and sea surface height were assimilated. The results showed that the multivariate background error covariance is useful in the EnKF system. We also tested the sensitivity of the EnKF algorithm to the localization and inflation of the background error covariance and the number of ensemble members. In the sensitivity tests, the ensemble spread as well as the root-mean square (RMS) error of the ensemble mean was assessed. The EnKF produces the optimal solution as the ensemble spread approaches the RMS error of the ensemble mean because the ensembles are well distributed so that they may include the true state. The localization and inflation of the background error covariance increased the ensemble spread while building up well-distributed ensembles. Without the localization of the background error covariance, the ensemble spread tended to decrease continuously over time. In addition, the ensemble spread is proportional to the number of ensemble members. However, it is difficult to increase the ensemble members because of the computational cost.

• 한국콘텐츠학회논문지
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• 제19권4호
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• pp.303-314
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• 2019

본 연구는 외국인 유학생 건강의 유지 및 증진을 위한 기초자료를 마련하고자 건강행태와 칫솔질행태의 실태를 분석하고 건강신념과의 관계를 SPSS WIN 12.0 분석해 유의성 있는 결과를 얻었다(p<.05). 건강신념의 전체적인 총 평균은 3.71이며 지각된 민감성은 2.99, 지각된 심각성은 3.47, 지각된 이익성은 4.35로 가장 높았다. 건강행태와 칫솔질행태에 따른 건강신념은 비음주가 건강신념과 지각된 민감성이 높았고 금연에서 건강신념과 지각된 이익성이 높았다. 칫솔질범위에서 지각된 민감성이 높았으며 칫솔질 교체시기에서 건강신념, 지각된 심각성과 이익성에서 높았다. 회귀분석 결과 비흡연(p=.009), 칫솔질 교환시기가 1-3개월(p=.000)이 건강신념이 높았다. 총괄적으로 유학생의 건강증진을 위해 올바른 건강 및 칫솔질행태에 대한 체계적인 교육이 이루어져야 할 것이다.

• Investigative Magnetic Resonance Imaging
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• 제26권2호
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• pp.125-134
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• 2022

Purpose: The aim of this study was to investigate the change in signal sensitivity over different acquisition start times and optimize the scanning window to provide the maximal signal sensitivity of [1-¹³C]pyruvate and its metabolic products, lactate and alanine, using spatially localized hyperpolarized 3D ¹³C magnetic resonance spectroscopic imaging (MRSI). Materials and Methods: We acquired 3D ¹³C MRSI data from the brain (n = 3), kidney (n = 3), and liver (n = 3) of rats using a 3T clinical scanner and a custom RF coil after the injection of hyperpolarized [1-¹³C]pyruvate. For each organ, we obtained three consecutive 3D ¹³C MRSI datasets with different acquisition start times per animal from a total of three animals. The mean signal-to-noise ratios (SNRs) of pyruvate, lactate, and alanine were calculated and compared between different acquisition start times. Based on the SNRs of lactate and alanine, we identified the optimal acquisition start timing for each organ. Results: For the brain, the acquisition start time of 18 s provided the highest mean SNR of lactate. At 18 s, however, the lactate signal predominantly originated from not the brain, but the blood vessels; therefore, the acquisition start time of 22 s was recommended for 3D ¹³C MRSI of the rat brain. For the kidney, all three metabolites demonstrated the highest mean SNR at the acquisition start time of 32 s. Similarly, the acquisition start time of 22 s provided the highest SNRs for all three metabolites in the liver. Conclusion: In this study, the acquisition start timing was optimized in an attempt to maximize metabolic signals in hyperpolarized 3D ¹³C MRSI examination with [1-¹³C] pyruvate as a substrate. We investigated the changes in metabolic signal sensitivity in the brain, kidney, and liver of rats to establish the optimal acquisition start time for each organ. We expect the results from this study to be of help in future studies.

• Weed & Turfgrass Science
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• 제1권4호
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• pp.69-75
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• 2012

설부소립균핵병 방제를 위한 살균제 반응을 조사하기 위하여 Typhula incarnata 균주를 2012년 용평에 3곳 골프장에서 채집하여 propiconazole, tebuconazole 및 azoxystrobin 살균제에 대하여 감수성을 평가하였다. 50개의 균주에 대한 실내에서 감수성을 평가를 위하여 4개의 다른 농도로 수행하였다. 균사생장을 효과적으로 50%까지 억제하는 농도인 $EC_{50}$은 tebuconazole이 가장 낮았다. Triazole 계인 tebuconazole의 평균 $EC_{50}$은 0.0048 ${\mu}g\;ml^{-1}$이며, 최소 $EC_{50}$은 0.0005 ${\mu}g\;ml^{-1}$ 농도이며, 최대 $EC_{50}$의 농도는 0.014 ${\mu}g\;ml^{-1}$이었다. 반면, Propiconazole의 평균 $EC_{50}$은 0.5825 ${\mu}g\;ml^{-1}$이고, $EC_{50}$의 범위는 0.078 ${\mu}g\;ml^{-1}$에서 1.651 ${\mu}g\;ml^{-1}$이었다. Strobilurin 계인 azoxystrobin은 평균 $EC_{50}$은 0.0278 ${\mu}g\;ml^{-1}$이고, 최소와 최대 $EC_{50}$은 범위는 0.0017 ${\mu}g\;ml^{-1}$에서 0.131 ${\mu}g\;ml^{-1}$이었다. Propiconazole, azoxystrobin 및 tebuconazole 살균제간의 $EC_{50}$ 사이에 상관 관계가 나타나지 않았으며, 이들 균주와 이들 살균제 간에 교차저항성도 없었다. 이 연구 결과 용평에서 채집한 T. incarnata 균주는 3종의 살균제에 대하여 실내감수성 시험에서 저항성 균주가 없다는 것을 확인할 수 있었다.

• Water Engineering Research
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• 제6권2호
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• pp.73-89
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• 2005

Two kinds of high resolution GCMs with the same spatial resolutions but with different schemes run by domestic and foreign agencies are used to clarify the usefulness and sensitivity of GCM for water resources applications for Korea. One is AMIP-II (Atmospheric Model Intercomparison Project-II) type GCM simulation results done by ECMWF (European Centre for Medium-Range Weather Forecasts) and the other one is AMIP-I type GCM simulation results done by METRI (Korean Meteorological Research Institute). Observed mean areal precipitation, temperature, and discharge values on 7 major river basins were used for target variables. Monte Carlo simulation was used to establish the significance of the estimator values. Sensitivity analyses were done in accordance with the proposed ways. Through the various tests, discrimination condition is sensitive for the distribution of the data. Window size is sensitive for the data variation and the area of the basins. Discrimination abilities of each nodal value affects on the correct association. In addition to theses sensitivity analyses results, we also noticed some characteristics of each GCM. For Korean water resources, monthly and small window setting analyses are recommended using GCMs.

• Child Health Nursing Research
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• 제11권4호
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• pp.415-426
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• 2005

Purpose: The purpose of this study was to identify relations among the parenting stress, maternal sensitivity to infant cues, parenting environment of first-time mothers. Method: The participants were 194 first-time mothers of babies aged 1-6 months who visited well-baby clinics in 5 hospitals. The data were collected from April 15 to June 15, 2003. Results: The parenting stress level was moderate with a mean score of 2.4(range 1-5). The parent domain and parent-child relationship domain of the parenting stress scale were significantly correlated with maternal sensitivity to infant feeding cues (r=-.178, p<.05; r=-.197, p<.01). Parenting stress was significantly correlated with childrearing environment(r=-2.19, p<.01). Parenting stress and childrearing environment were significantly different according to the educational level of the mothers and their prenatal care. Conclusions: Nursing interventions to reduce parenting stress in first-time mothers are needed to improve maternal sensitivity to infant cues and childrearing environment which foster infant development.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.92-99
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• 2013

High oil price and global warming problem are being continued all over the world. For this reason, fuel economy and emission of greenhouse gas are regulated by law in many countries. Therefore many companies are researching and producing hybrid electric vehicles (HEVs) which substitute conventional internal combustion engine vehicle. However, these researches and productions are restricted to mainly passenger cars. Because of cost and physical problems, commercial vehicles are difficult to evaluate fuel economy. So simulations are important and it is necessary to know how sensitive parameters that enter into simulation affect. In this paper, forward simulations using AVL Cruise were conducted for analysis of fuel economy for parallel hybrid bus and were repeated by changing each parameter. Based on these results, root mean square errors (RMSE) are calculated for analysis of fuel economy sensitivity. The number of target parameters are 15. These parameters were classified with high and low sensitivity parameter relatively.

• 대한조선학회논문집
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• 제57권2호
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• pp.80-87
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• 2020

As the Arctic sea ice decreases due to various reasons such as global warming, the demand for ships and offshore structures operating in the Arctic region is steadily increasing. In the case of sea ice, the anisotropy is caused by the uncertainty inside the material. For most of the research, nevertheless, estimating the ice load has been treated deterministically. With regard to this, in this paper, a four-point bending strength analysis of an ice specimen was attempted using a stochastic finite element method. First, spatial distribution of the material properties used in the yield criterion was assumed to be a multivariate Gaussian random field. After that, a direct method, which is a sort of stochastic finite element method, and a sensitivity method using the sensitivity of response for random variables were proposed for calculating the probabilistic distribution of ice specimen strength. A parametric study was conducted with different mean vectors and correlation lengths for each material property used in the above procedure. The calculation time was about ten seconds for the direct method and about three minutes for the sensitivity methods. As the cohesion and correlation length increased, the mean value of the critical load and the standard deviation increased. On the contrary, they decreased as the friction angle increased. Also, in all cases, the direct and sensitivity methods yielded very similar results.