• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.709-721
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• 2008

This paper is to test the applicability of ModKIMSTORM (Modified KIneMatic Wave STOrm Runoff Model) by applying it to Namgangdam watershed of $2,293km^2$. Model inputs (DEM, land use, soil related information) were prepared in 500 m spatial resolution. Using five typhoon events (Saomi in 2000, Rusa in 2002, Maemi in 2003, Megi in 2004 and Ewiniar in 2006) and two storm events (May of 2003 and July of 2004), the model was calibrated and verified by comparing the simulated streamflow with the observed one at the outlet of the watershed. The Pearson's coefficient of determination $R^2$, Nash and Sutcliffe model efficiency E, the deviation of runoff volumes $D_v$, relative error of the peak runoff rate $EQ_p$, and absolute error of the time to peak runoff $ET_p$ showed the average value of 0.984, 0.981, 3.63%, 0.003, and 0.48 hr for 4 storms calibration and 0.937, 0.895, 8.08%, 0.138, and 0.73 hr for 3 storms verification respectively. Among the model parameters, the stream Manning's roughness coefficient was the most sensitive for peak runoff and the initial soil moisture content was highly sensitive for runoff volume fitting. We could look into the behavior of hyrologic components from the spatial results during the storm periods and get some clue for the watershed management by storms.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.2
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• pp.23-32
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• 2023

Probabilistic and deterministic analyses are implemented for the armor units of rubble foundation mound of composite breakwaters which is needed to protect the upright section against the scour of foundation mounds. By a little modification and incorporation of the previous empirical formulas that has commonly been applied to design the armor units of foundation mound, a new type formula of stability number has been suggested which is capable of taking into account slopes of foundation mounds, damage ratios of armor units, and incident wave numbers. The new proposed formula becomes mathematically identical with the previous empirical formula under the same conditions used in the developing process. Deterministic design have first been carried out to evaluate the minimum weights of armor units for several conditions associated with a typical section of composite breakwater. When the slopes of foundation mound become steepening and the incident wave numbers are increasing, the bigger armor units more than those from the previous empirical formula should be required. The opposite trends however are shown if the damage ratios is much more allowed. Meanwhile, the reliability analysis, which is one of probabilistic models, has been performed in order to quantitatively verify how the armor unit resulted from the deterministic design is stable. It has been confirmed that 1.2% of annual encounter probability of failure has been evaluated under the condition of 1% damage ratio of armor units for the design wave of 50 years return period. By additionally calculating the influence factors of the related random variables on the failure probability due to those uncertainties, it has been found that Hudson's stability coefficient, significant wave height, and water depth above foundation mound have sequentially been given the impacts on failure regardless of the incident wave angles. Finally, sensitivity analysis has been interpreted with respect to the variations of random variables which are implicitly involved in the formula of stability number for armor units of foundation mound. Then, the probability of failure have been rapidly decreased as the water depth above foundation mound are deepening. However, it has been shown that the probability of failure have been increased according as the berm width of foundation mound are widening and wave periods become shortening.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.100-112
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• 2005

Soil temperature was measured from the surface to 40 cm depth at three stations with different heights in tidal flat of Gomso Bay, west coast of Korea, for one month in every season 2004 to examine the thermal structure and the variation. Mean temperature in surface layer was higher in summer and lower in winter than in lower layer, reflecting the seasonal variation of vertically propagating structure of temperature by heating and cooling from the tidal flat surface. Standard deviation of temperature decreased from the surface to lower layer. Periodic variations of solar radiation energy and tide mainly caused short term variation of soil temperature, which was also intermittently influenced by precipitation and wind. Time series analysis showed the power spectral energy peaks at the periods of 24, 12 and 8 hours, and the strongest peak appeared at 24 hour period. These peaks can be interpreted as temperature waves forced by variations of solar radiation, diurnal tide and interaction of both variations, respectively. EOF analysis showed that the first and the second modes resolved 96% of variation of vertical temperature structure. The first mode was interpreted as the heating antl cooling from tidal flat surface and the second mode as the effect of phase lag produced by temperature wave propagation in the soil. The phase of heat transfer by 24 hour period wave, analyzed by cross spectrum, showed that mean phase difference of the temperature wave increased almost linearly with the soil depth. The time lags by the phase difference from surface to 10, 20 and 40cm were 3.2,6.5 and 9.8 hours, respectively. Vertical thermal diffusivity of temperature wave of 24 hour period was estimated using one dimensional thermal diffusion model. Average diffusivity over the soil depths and seasons resulted in $0.70{\times}10^{-6}m^2/s$ at the middle station and $0.57{\times}10^{-6}m^2/s$ at the lowest station. The depth-averaged diffusivity was large in spring and small in summer and the seasonal mean diffusivity vertically increased from 2 cm to 10 cm and decreased from 10 cm to 40 cm. Thermal propagation speeds were estimated by $8.75{\times}10^{-4}cm/s,\;3.8{\times}10{-4}cm/s,\;and\;1.7{\times}10^{-4}cm/s$ from 2 cm to 10 cm, 20 cm and 40 cm, respectively, indicating the speed reduction with depth increasing from the surface.

• Sleep Medicine and Psychophysiology
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• v.3 no.1
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• pp.47-55
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• 1996

Narcolepsy is characterized by sleep attack with excessive daytime sleepiness(EDS), cataplexy, sleep paralysis, and hypnagogic hallucination. Paradoxically, narcoleptics tend to complain of frequent arousals and shallow sleep during the night time despite their excessive sleepiness. However, nocturnal sleep fragmentation in narcoleptics is relatively ignored in treatment strategies, compared with sleep attack/EDS and cataplexy. In our paper, we attempted to investigate further on the poor nocturnal sleep in narcoleptics and to discuss possible treatment interventions. Out of consecutively seen patients at Seoul National University Sleep Disorders Clinic and Division of Sleep Studies, we recruited 57 patients, clinically assessed as having sleep attack and/or EDS. Nocturnal polysomnography and multiple sleep latency test(MSLT) were done in each of the subjects. We selected 19 subjects finally diagnosed as narcolepsy(mean age $26.0{\pm}18.3$ years, 16 men and 3 women) for this study, depending on the nocturnal polysomnographic and MSLT findings as well as clinical history and symptomatology. Any subject co-morbid with other hypersomnic sleep disorders such as sleep apnea or periodic limb movements during sleep was excluded. Sleep staging was done using Rechtschaffen and Kales criteria. Sleep parameters were calculated using PSDENT program(Stanford Sleep Clinic, version 1.2) and were compared with the age-matched normal values provided in the program. In narcoleptics, compared with the normal controls, total wake time was found to be significantly increased with significantly decreased sleep efficiency(p<.01, p<.05, respectively), despite no difference of sleep period time and total sleep time between the two groups. Stage 2 sleep%(p<.05), slow wave sleep%(p<.05), and REM sleep%(p<.01) were found to be significantly decreased in narcoleptics compared with normal controls, accompanied by the significant increase of stage 1 sleep%(p<.01). Age showed negative correlation with slow wave sleep%(p<.05). The findings in the present study indicate significant fragmentation of nocturnal sleep in narcoleptics. Reduction of REM sleep% and the total number of REM sleep periods suggests the disturbance of nocturnal REM sleep distribution in narcoleptics. No significant correlations between nocturnal polysomnographic and MSLT variables in narcoleptics suggest that nocturnal sleep disturbance in narcoleptics may be dealt with, in itself, in diagnosing and managing narcolepsy. With the objective demonstration of qualitative and quantitative characteristics of nocturnal and daytime sleep in narcoleptics, we suggest that more attention be paid to the nocturnal sleep fragmentation in narcoleptics and that appropriate treatment interventions such as active drug therapy and/or circadian rhythm-oriented sleep hygiene education be applied as needed.

• Journal of Convergence for Information Technology
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• v.9 no.3
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• pp.104-111
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• 2019

The purpose of this study is to know the change of brain wave with stress by SUKI pressure alternative therapy. The experiment group was 12 students(male 6/female 6) with complained upper trapezius pain. Calculated the brain wave before and after stimulate the upper trapezius trigger point by SUKI and the stimulate time was 3min each persons(FP2, F3, F4, FP1, T3, T4, P3, P4). the experimet periods was 5times in a weeks with EEG(QEEG-S). The Date collecting used by Telescan(LXE5209). All the data was analyzed with SPSS 22.0 for window program. To compare the differences before and after the point pressure method, a corresponding sample of t-test was performed, and the statistical significance level was p<.05. The results was followed. The points of Fp2, F3, F4(*p<0.049, *p<0.042, *p<0.019) of EEG was showed a significant differences but Fp1, T3, T4, P3, P4 points did not showed. The SUKI alternative medicine techniques had a reduced effects for the some kind of brain stress. It is need to continuous research in the future.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.1
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• pp.41-52
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• 2017

This paper presents a numerical and experimental study of sloshing loads on liquefied natural gas (LNG) vessels. Conventional LNG carriers with membrane-type cargo systems have filling restrictions from 10% to 70% of tank height. The main reason for such restrictions is high sloshing loads around these filling depths. However, intermediate filling depths cannot be avoided for most LNG vessels except the LNG carrier. This study attempted to design a membrane-type LNG tank with a modified lower-chamfer shape that allows all filling operations. First, numerical sloshing analysis was carried out to find an efficient height of the lower-chamfer that can reduce sloshing pressure at partially filled conditions. The numerical sloshing analysis program SHI-SLOSH was used for numerical simulation; this program is based on SOLA-VOF. The effectiveness of the newly designed tanks was validated by 1:50-scale three-dimensional tank tests. A total of three different tanks were tested: a conventional tank and two modified tanks. As test conditions, various filling depths and wave periods were considered, and the same test conditions were applied to the three tanks. During the test, slosh-induced dynamic pressures were measured around the corners of the tank wall. The measured pressure data were post-processed and the pressures of the three different tanks were statistically compared in several ways. Experimental results show that the modified tanks were quite effective in reducing sloshing loads at low filling conditions. This study demonstrated the possibility of all filling operations for LNG cargo containment systems.

• Korean Journal of Social Welfare
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• v.64 no.2
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• pp.185-212
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• 2012

This study examines changes in income inequality and income mobility associated with a transition to old age. In understanding the dynamics of income distribution over the later life course, it is important to explore the changes in income dispersion and the changes in relative income positions jointly. Data come from Korean Labor and Income Panel Study(KLIPS) 2nd, 7th, 12th wave. The results are as follows. First, a transition to old age is associated with an increase in income inequality. The Gini index of inequality increased steadily over the life course. Second, a transition to old age is associated with substantial income mobility. The Spearman's rank correlation coefficient between two periods was the lowest at the time of the transition. Increasing income dispersion and significant income mobility can be conceptualized as "income insecurity", since the older population are less likely to cope with income fluctuations. Third, in explaining such changes over time, changes in work life during old age and a subsequent decrease in earnings seem to be the most influential factor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.679-686
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• 2020

In this study, the seismic vulnerability of public river levees was analyzed quantitatively. Input seismic waves were generated in Pohang seismic waves in return periods of 200, 500, 1000, and 2400 years. The behavior of the levee was analyzed by seismic vulnerability analysis according to the return period. The displacement that occurs during an earthquake showed the same tendency as the input seismic wave and was largest in the return period of 2400 years. An analysis of the sliding stability revealed a 31.5% and 26.7% decrease in the sliding safety factor for the return period of 2400 for the landside and waterside, respectively. An examination of liquefaction by the q/p' ratio showed that the seepage line inside the embankment rises due to earthquakes. As a result, in the case of a return period of 2400 years, most embankments generate liquefaction, making them vulnerable to earthquakes. Through this research, it will be necessary to re-establish domestic seismic-design standards and establish clear standards for the results through a dynamics method.

• Journal of Ecology and Environment
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• v.35 no.3
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• pp.213-225
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• 2012

Sap flux density (SFD) measurements were used, in combination with morphological characteristics of trees and forest structure, to calculate whole-tree transpiration, stand transpiration (St) and mean canopy stomatal conductance (Gs). Analysis based on the relationships between the morphological characteristics of trees and whole tree water use, and on the responses of SFD and Gs to short wave radiation (RR), vapor pressure deficit (VPD) and soil water content (SWC) during drought and non-drought periods were conducted. The results showed a strong positive correlation between whole tree transpiration and both tree diameter at breast height (DBH) ($r^2$ = 0.95, P < 0.05) and sapwood area (SA) ($r^2$ = 0.98, P < 0.05). Relationships between SFD and DBH ($r^2$ = 0.25), as well as SA ($r^2$ = 0.17) were weak. Daily SFD of Quercus serrata Thunb was closely related to VPD and RR. Although operating at different time scales, RR and VPD were important interacting environmental controls of tree water use. SFD increased with increasing VPD (<1 kPa) and RR. SWC had a considerable effect on stand transpiration during the drought period. The relationships between SFD, VPD and RR were distorted when SWC dropped below 35%.

• Journal of Periodontal and Implant Science
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• v.33 no.2
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• pp.139-147
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• 2003

The roots of teeth exposed by gingival recession, may be successfully covered by various type of gingival grafting procedures. Vascularization of the recipient site is an essential determinant of the grafts' survival during the first healing stages. It has been suggested that a procedure by which they stimulate the periosteum presurgically will induce the proliferation of neo-endothelium in the site to be operated. The purpose of this study is to evaluate the variations in the gingival blood flow during 4weeks after periosteal stimulation in patient scheduled to receive gingival grafts and to compare variations in the gingival blood flow between smoker and non-smoker. Laser Doppler Flowmetry(floLAB(R), Moor Instruments Ltd, England ; wave length = 780mm. Max. power =l.6mW) was used to measure the gingival blood flow. 112 sites of 68 male patients (32 smokers and 36 non-smoker), aged between 23 and 48 years (smoker : 24-44 years. mean=32.6, non-smoker : 23-48 years, mean=28.5) were monitored for the blood flow. Gingival blood flow measured at before periosteal stimulation, 1-, 2-, 3-, and 4-weeks after periosteal stimulation from 10 a.m. to 2 p.m. The difference of blood flow in each measuring time, each measuring site and between smokers and non-smokers were statistically analyzed by MANOVA. The results were as follows : (1) Blood flow stayed increased for 2 weeks, and then, it was a tendency to decrease(p<0.05). (2) There was no statistically significant difference of blood flow change between smokers and non-smokers. (3)The blood flow at middle site had lower than mesial and distal site during the measuring periods(p<0.05). The present study suggested that blood flow change following periosteal stimulation was significant difference, thus periosteal stimulation before gingival graft might induce favorable results in gingival recession patient.