• Journal of Korean Neurosurgical Society
• /
• v.66 no.4
• /
• pp.382-392
• /
• 2023

Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

• Journal of Animal Science and Technology
• /
• v.46 no.4
• /
• pp.517-524
• /
• 2004

The objective of this study was to investigate the environmental effects on duration time of milk flow, peak milk flow, and average milk flow in teats, and to estimate their relationships with milk yields in morning and evening milking, and to provide fimdamental information for the further study on their relationships with clinical mastitis and somatic cell in milk. A total of 6,768 milking records were studied in 72 Holstein cows. The influences of season, parity, lactation month, and milking interval on characteristics of milk flow considering in linear model were significant(p<.05). Duration of milk flow was longest at milking in fall, past first parity and second month of lactation, and with milking interval over than 13.5hrs. Average milk flow rate and peak milk flow rate were highest at milking in summer, past first parity and 8${\sim}$10 months of lactation, and with milking interval over than 13.5hrs. Milk flow rate was positively correlated to milk yield, and negatively correlated to the duration of milk flow. However duration milk flow was positively correlated to the milk yield with high level of correlation coefficient(+.60). For the establishment of optimum selection criteria on these traits, other aspects such as the udder health, disease and respective economic weights of milk flow characteristics in this study must be considered to develop the indices.

• Journal of Environmental Science International
• /
• v.11 no.6
• /
• pp.507-517
• /
• 2002

Cheeka Peak is a unique site for monitoring the background chemistry and aerosol contents of pristine marine air at mid-latitude. During long-range onshore winds that occur frequently throughout the year, it is predicted to have the cleanest air in the northern hemisphere. Measurements of CO and O$_3$were conducted at Cheeka Peak Observatory(CPO) on the northwestern tip of Washington state, USA during March 6 ∼May 29, 2001. The data have been segregated to quantify the mixing ratio of these species in the Pacific marine atmosphere. Also the marine air masses were further classified into four categories based on 10-day backward isentropic trajectories; high, mid, and low latitude and those which had crossed over the Asian industrial region. The diurnal variation of CO and O$_3$at CPO showed a similar to tendency of background measurement site. When marine air mass flowed to CPO, CO concentration was lower and O$_3$was similar or higher than those of total data. The westerly flow from ocean, not easterly from continent occurred the high concentration of CO and O$_3$at CPO. Using the trajectory segregation of marine air mass, the comparison of concentration according to latitude calculated. the CO concentration of Asian trajectory was lower than other latitudes, O$_3$concentration was higher.

• Nuclear Engineering and Technology
• /
• v.30 no.1
• /
• pp.8-16
• /
• 1998

In this work a method to detect the vibrational peak and to decide the vibrational mode of detected peak for core internal vibration monitoring system which is particularly concerned on the core support barrel (CSB) and fuel assemblies is developed. Flow induced vibration and aging process in the reactor internals cause unsoundness of the internal structure. In order to monitor the vibrational status of core internal, signals from the ex-core neutron detectors are transformed into frequency domain. By analyzing transformed frequency domain signal, an analyst can acquire the information on the vibrational characteristics of the structures, i.e., vibration frequencies of each component, vibrational level, modes of vibration, and the causes of the abnormal vibration, if any. This study is focused on the development of the automated monitoring system. Several methods are surveyed to define the peaks in power spectrum and fuzzy theory is used to automatic detection of the vibrational peaks. Fuzzy algorithm is adopted to define the modes of vibration using the peak values from fuzzy peak recognition, phase spectrum, and coherence spectrum.

• Childhood Kidney Diseases
• /
• v.5 no.1
• /
• pp.9-14
• /
• 2001

Purpose : This study was undertaken to investigate clinical aspects of nutcracker syndrome in children including sexual distribution, age of onset, the ratio of peak flow velocity between the narrowed and dilated portions in the left renal vein and prevalence of hematuria or proteinuria. Materials and Method : The subjects included 30 patients diagnosed with nutcracker syndrome using Doppler sonography from September 1999 to January 2001 in Severance Hospital, Department of Pediatric Nephrology. The diagnostic criteria for nutcracker syndrome was a peak flow velocity of ratio is more than 5.0. Results : Patients consisted of 14 males and 16 females. The mean age was 9.19${\pm}$2.31 years old and the ratio of peak flow velocity was 8.52${\pm}$2.24. Age of onset us higher in males 9.68${\pm}$2.82 year old than in females, 8.76${\pm}$1.72 year old respectively(P<0.05). But there was no difference in the ratio of peak flow velocities ; 8.45${\pm}$2.31 in the male group , 8.58${\pm}$2.25 in the female group(P>0.05). There was no difference in the age of onset and the ratio of peak flow velocity between patients with hematuria and without hematuria. Among patients with nutcracker syndrome, 24 cases of hematuria, 3 cases of proteinuria only, and 3 cases of hematuria with proteinuria. Conclusion : In children of school age, early diagnosis of nutcracker syndrome and consistent follow up is worthy of consideration, especially ill the prevention of sequelae. (J. Korean Soc Pediatr Nephrol 5 : 9-14, 2001)

• Journal of Korea Water Resources Association
• /
• v.30 no.6
• /
• pp.777-785
• /
• 1997

This study was conducted to clarify the hydrological characteristics of subsurface flow through a soil matrix and macropores. The research facility was set up in a 20m-1ong trench excavated down to bedrock at the base of a hillslope in the Panola catchment under USGS Georgia district. 13 macropores were found on the trench face and 6 major macropores were monitored. Matrix and macropore flow were measured during 95.5mm rainfall on March, 6 to 7. 1996. Macropore flow had great influence on formation of peak flow because the delivery time to Peak flow of macropore flow were faster about 10hrs than those of matrix flow. Matrix flow continued to recess for 3 days. On the other hand, macropore flow stopped within 12hrs after the event ceased. This means that matrix flow controls the recession part. The spatial variations of matrix and macropore flow between each trough and collector were very large by a wide range of 8,655.3 $\ell$ to 17.8 $\ell$ . The bed rock surface topography relates closer with the spatial variations of the flow than the surface one.

• Journal of Environmental Health Sciences
• /
• v.30 no.2
• /
• pp.140-148
• /
• 2004

To evaluate the acute effects of fine particles on pulmonary function, a longitudinal study was conducted. This study was carried out for the schoolchildren (3rd and 6th grades) living in Beijing, China. Each child was provided with a mini-Wright peak flow meter and a preformatted health symptom diary for 40 days, and was trained on their proper use. Participants were instructed to perform the peak flow test three times in standing position, three times a day (9 am, 12 pm, and 8 pm), and to record all the readings along with the symptoms (cold, cough, and asthmatic symptoms) experienced on that day. Daily measurement of fine particles (PM$_{10}$ and PM$_{2.5}$) was obtained in the comer of the playground of the participating elementary school for the same period of this longitudinal study. The relationship between daily peak expiratory flow rate (PEFR) and fine particle levels was analyzed using a mixed linear regression models including gender, height, the presence of respiratory symptoms, and daily average temperature and relative humidity as extraneous variables. The total number of students participating in this longitudinal study was 87. The range of daily measured PEFR was 253-501$\ell$/min. In general, the PEFR measured in the morning was lower than the PEFR measured in the evening (or afternoon) on the same day. The daily mean concentrations of PM$_{10}$ and PM$_{2.5}$ over the study period were 180.2$\mu\textrm{g}$/㎥ and 103.2$\mu\textrm{g}$/㎥, respectively. The IQR (inter-quartile range) of PM$_{10}$ and PM$_{2.5}$ were 91.8$\mu\textrm{g}$/㎥ and 58.0$\mu\textrm{g}$/㎥. During the study period, the national ambient air quality standard of 150$\mu\textrm{g}$/㎥ (for PM$_{10}$) was exceeded in 23 days (57.5%). The analysis showed that an increase of 1$\mu\textrm{g}$/㎥ of PM$_{10}$ corresponded to 0.59$\mu\textrm{g}$/㎥ increment of PM$_{2.5}$. Daily mean PEFR was regressed with the 24-hour average PM$_{10}$ (or PM$_{2.5}$) levels, weather information such as air temperature and relative humidity, and individual characteristics including gender, height, and respiratory symptoms. The analysis showed that the increase of fine particle concentrations was negatively associated with the variability in PEFR. The IQR increments of PM$_{10}$ or PM$_{2.5}$ (at 1-day time lag) were also shown to be related with 1.54 $\ell$/min (95% Confidence intervals: 0.94-2.14) and 1.56$\ell$/min (95% CI: 0.95-2.16) decline in PEFR.R.ine in PEFR.ine in PEFR.

• Tuberculosis and Respiratory Diseases
• /
• v.72 no.1
• /
• pp.24-29
• /
• 2012

Background: Measurement of peak expiratory flow rate (PEFR) in a follow-up examination for a chronic airway disease is useful because it has the advantages of being a simple measurement and can be repeated during examination. The aim of this study was to examine the annual decrease of PEFR in asthma and chronic obstructive pulmonary disease (COPD) patients and to confirm the factors which influence this decrease. Methods: From May, 2003 to September, 2010, the annual decrease of PEFR was obtained from asthma and COPD patients attending an outpatient pulmonary clinic. PEFR was measured using a Mini-Wright peak flow meter (Clement Clarke International Ltd. UK), and we conducted an analysis of factors that influence the change of PEFR and its average values. Results: The results showed an annual decrease of $1.70{\pm}12.86$ L/min the asthmatic patients and an annual decrease of $10.3{\pm}7.32$ L/min in the COPD patients. Age and $FEV_1$ were the predictive factors influencing change in asthma, and $FEV_1$ and smoking were the predictive factors influencing change in COPD. Conclusion: We confirmed the annual decreasing PEFR in patients with chronic airway disease and identified factors that work in conjunction with $FEV_1$ to influence the change.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.8 no.1
• /
• pp.1011-1034
• /
• 1966

This thesis is the final report which has long been studied by the author to obtain the design basis for various hydrological constructions with the specific system suitable to the natural environmental conditions in Korea. This report is divided into two parts: one is to estimate runoff volume from watersheds and the other to estimate the peak discharge for a single storm. According to the result of observed runoff record from watersheds, it is known that Kajiyama formula is useful instrument in estimating runoff volume from watersheds in this country. But it has been found that this formula shows us 20-30% less than the actual flow. Therefore, when wihed to bring a better result, the watershed characteristics coefficient in this formula, that is, f-value, should be corrected to 0.5-0.8. As for the method to estimate peak discharge from drainage basin, the author proposes to classify it in two ways; one is small size watershed and the other large size watershed. The maximum -flood discharge rate $Q_p$ and time to peak Pt obtained from the observed record on the small size watershed are compared by various methods and formulas which are based upon the modern hydrological knowledge. But it was fou.d that it. was not a satisfied result. Therefore, the author proposes. tocomputate $Q_p$, to present 4.0-5.0% for the total runoff volume ${\Sigma}Q$.${\Sigma}Q$ is computed under the assumption of 30mm 103s in watershed per day and to change the theoritical total flow volume to one hour dura tion total flow rate when design daily storm is given. Time to peak Pt is derived from three parameters which are u,w,k. These are computed by relationship between total runoff volume (ha-m unit)and $Q_p$. (C.M.S. unit). Finally, the author checked out these results obtained from 51 hydrographs and got a satisfied result. Therefore the author suggested the model of design dimensionless unit-hydrograph. And the author believes that this model will be much available at none runoff record river site. In the large size watersheds in Korea when the maximum discharge occurs, the effective rainfall is two consequtive stormy days. So the loss in watershed was assutned as 6Omm/2days,and the author proposed 3-hour-daration hydrograph flow distribution percentage. This distribution percentage will be sure to form the hydrograph coordinate.

• Journal of Korean Society for Geospatial Information Science
• /
• v.15 no.2 s.40
• /
• pp.33-42
• /
• 2007

A physical-based aggregation method was suggested to estimate surface roughness, which adequately represents the spatial heterogeneity of vegetation factors, from land cover property obtained from the remote sensing data. For the sensitivity analysis of surface roughness, the peak flow, peak time, and total volume were simulated by the NWS-PC. Effects of surface roughness estimated by three different integration methods (predominant, arithmetic mean, and aggregation approach) on the conceptual rainfall-runoff model parameters was analyzed. In the preliminary sensitivity test to surface roughness, the peak time had 10% variation and total volume had 2% variation. The peak time increased with surface roughness. A physical-based aggregation method was better than the existing method in the Soyanggang Dam basin for the results of STDEV, RMSE, NSE, and PME, but difference between them were small. The parameters related on the total baseflow were changed significantly with change of the surface roughness.