• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.163-167
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• 2003

Based on the transient finite difference solution of Richards' equation, an infiltration model is developed to analyze temporal variation of precipitation recharge in the region of monsoon climates. Simulation results obtained by using time series data of 20-year daily precipitation and pan evaporation indicate that a linear relationship between the annual precipitation and the annual recharge holds for the soils under the monsoon climates with varying degrees of the correlation coefficient depending on the soil types. A sensitivity analysis reveals that the water table depth has little effects on the recharge for the sandy soil, whereas, for the loamy and silty soils, rise of the water table at shallow depths causes increase of evaporation by approximately 100㎜/yr and a corresponding decrease in recharge. A series of simulations for two-layered soils illustrate that the amount of recharge is dominantly determined by the soil properties of the upper layer, although the temporal variation of recharge is affected by both layers.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.887-889
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• 2016

본 연구는 전도성 섬유를 양말에 부착하여 발바닥에서 심전도(ECG, Electrocardiogram) 신호를 검출하였다. 발바닥에서 측정한 심전도 신호와 손목에서 측정한 심전도 신호에 Pan-Tompkins algorithm을 적용하였고 R-R interval을 검출하였다. 이후 발바닥과 손목에서 측정된 심전도의 유의성을 검출하기 위해 비모수 검정법인 Spearman검정을 사용하여 상관분석을 수행하였다. 상관분석 결과, 유의확률 p=0.00에서 correlation coefficient=0.901로 두 데이터는 강한 양의 선형 관계에 있는 것으로 나타났다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.613-618
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• 2007

The real vehicle crash experiment is the best way to evaluate the performance of a guardrail. However the experiment is very expensive because of high cost of vehicles and guardrail installation. Thus in this study, crash simulation of a vehicle against a steel guardrail is performed using LS-DYNA. There are many researches on the impact of a vehicle against a guardrail. However the friction between a vehicle and a guardrail is not considered, although it affects considerably the behavior of a guardrail. In this paper, the friction coefficient is applied to evaluate correctly the performance of a guardrail.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.378-383
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• 2000

The daily streamflow in the Yalu watershed located in the north-estern part of China was simulated by the DAWAST model. The parameters of model were calibrated by optimization technique with the input data of daily rainfall and pan evaporation occurred from 1997 to 1998, and they were Umax of 404mm, Lmax of 39mm, FC of 104mm, CP of 0.018, and CE of 0.003, respectively. Model verification tests were carried out with a data of 1996, and the results were generally satisfactory. Root mean square error was 0.3mm and Percent error in volume was 9.7%, and Correlation coefficient was 0.941.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.250-253
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• 2004

Emphasis has been placed on thin plate fabrication of plain woven carbon fabric reinforced Al matrix composites using liquid pressing process. The composite has potential applications for PDP rear plate. The process is to use the low pressure for infiltration of Al melt into plain woven carbon fabric as the Al melt is pressurized directly. The minimum pressure required for the infiltration was calculated from force balance equation, permeability measurements and compaction behavior of carbon fiber. Also, the melting temperature and the holding time have been optimized. In order to measure coefficient of thermal expansion (CTE) of the composites, the thermal strain measurement using strain gage was performed and the thermal conductivity of the composites was measured using laser flash method. The constituent materials of the composite are PAN type carbon fibers as reinforcements and 6061 Al alloys as matrices.

• Journal of Korean Public Health Nursing
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• v.24 no.2
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• pp.197-210
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• 2010

Purpose: The study investigated the relationships among perceived stress, mental health, and social support in community residents. Method: A self-reporting questionnaire was completed by 302 community residents aged 19-64-years-of-age from October 7 to November 30, 2008. Assessment tools were an The established perceived stress scale, standardized mental health scale, and established social support scale. The data was analyzed by descriptive statistics, t-test, one-way ANOVA, Scheffe's test, and Pearson's correlation coefficient using the SPSS WIN 12.0 program. Result: Significantly negative correlations were evident between perceived stress and social support, and between social support and mental health. But, there was a significantly positive correlation between perceived stress and mental health. Conclusion: It is necessary to develop a strategy to decrease perceived stress, improve mental health, and increase social support for community residents.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.230-235
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• 2014

Two-step quadrature phase-shifting digital holography based on the calculated intensity of a reference wave is proposed. In the Mach-Zehnder interferometer (MZI) architecture, the method only records two quadrature-phase holograms, without reference-wave intensity or object-wave intensity measurement, to perform object recoding and reconstruction. When the reference-wave intensity is calculated from the 2D correlation coefficient (CC) method that we presented, the clear reconstruction image can be obtained by some specific algorithm. Its feasibility and validity were verified by a series of experiments with 2D objects and 3D objects. The presented method will be widely used in real-time or dynamic digital holography applications.

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.2
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• pp.23-29
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• 1987

This study was fulfilled by the floating lysimeter method at the experimental farm of Kon-Kuk University from August to November of 1986 to investigate the amount of evapotranspiration by the growing periods, evapotranspiration ratio, amount of watering per one time, days of intermission, soil moisture extraction pattern and crop coefficient of the Chinese cabbage cultivated in the sandy loam soil at the watering point of pF2.O. The results obtained are summarized as follows: 1.The total evapotranspiration during the growing period was 267.2mm, which was 3. 99mm by daily average, and the maximum evapotranspiration showed in the mid ten days of September with the value of 5.81mm I day. 2.The evapotranspiration ratio by the growing stages increased from the last ten days of September and showed maximum in the beginning of October, and the average evapotranspiration ratio was 1.4. 3.The days of watering intermission at the watering point of pF2.O was 2.4 days, and the average yield per plant was 3,228 g. 4. The soil moisture extraction pattern in the initial stage was 78.9 % in the 1st and 2nd soil layer and 21.1 % in the 3rd and 4th layer, and the mid-season stage, the moisture extraction proportion of the under layer accounted for 38.8 % which showed that the root elongated to the lowest soil layer. 5.The average crop coefficient(Kc) of the tested crop during the growing period was 0.67 by Penman equation and 2.36 by Pan Evaporation equation, which showed high difference by the calculation methods, and the changes of crop coefficient by the growing stages by Penman equation was favorable than those calculated by other met-hods.

• Journal of the Korean Professional Engineers Association
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• v.2 no.6_7
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• pp.12-23
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• 1969

The purpose of this study is to find out the reasonable amount of evapo-transpiration required for the paddy rice plant during the whole growing season. So, on the basis of the 3year experimental data concerning the evapo-transpiration from 1966 to 1968, the author obtained the following results. 1) The leaf area index in the densely planted plot is generally higher than that in the conventionally planted one during the first half of growing season. So, the coefficient of transpiration in the former plot is some what higher than in the latter, and the coefficient of water surface evaporation under the plant cover has the inverse relation between both plots. 2) It is unreasonable that coefficient of evapo-transpiration is applied to the calculation of the evapo-transpiration requirments of each growing stage, because a certain degree of variation in meteorological factors and in the thickness of the plant growth is involved in it. 3) It is most reasonable that the rate of transpiration and of the water surface evaporation is applied to the calculation of the transpirated amount and evaporated one in each growing stage because it shows almost constant value in spite of any meteorological conditions in so far as the variety of rice, planted density and control of applying fertilizer are same and the disease and blight are negligible. 4) The ratio of the amount of transpiration to the weight of the whole air dried yields has the tendency of decreasing as that of the yields increase, having almost constant value despite the amount of pan evaporation; and the value is about 210 when the weight of root parts is included to that of the yields. 5) Although the required amount of transpiration during the whole growing season can be calculated with the above ratio, fig. 7 showing the relation between the amount of transpiration and the weight of the yields is more reasonable and will be convinient to find it. And the requirements of water surface evaporation during the same season can also be directly found with the weight of air dried straw refering to fig.8.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.733-740
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• 1994

Oxidized-PAN fiber reinforced composite(OFRP), carbon fiber reinforced composite(CFRP), aramid fiber reinforced composite(AFRP), and glass fiber reinforced composite(GFRP) were fabricated with phenolic resin matrix by hot press molding. We tested the friction coefficient and wear rate varying with fiber weight fraction and observed the effect of fibers according to characteristics of individual reinforcement. When the amount of aramid fiber was 45wt%, average friction coefficient was maximum value of 0.353~0.383, where as, when the amount of pitch based carbon fiber was 45wt%, average friction coefficient was the lowest value of 0.164~0.190. The wear rate of AFRP and CFRP was low, but that of GFRP and OFRP increases drastically in the case of increasing of fiber weight fraction. Wear diagram of OFRP was unstable, but that of CFRP and AFRP was a bit stable. Through very unstable diagram of GFRP, we found that friction stability of GFRP was the lowest.