• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.29-33
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• 2002

A procedure of free span and fatigue analysis of offshore pipelines was made per DNV-RP-F105, 2002. The new method includes the axial force and deflection load in pipelines. The screening criteria were used to calculate the allowable span lengths. The screening criteria allow small amplitudes of vortex-induced vibration due to wave and current loading. However, the induced pipe stress is very small and usually below the limit stress of a typical S-N curve. A simplified method was established to calculate the fatigue damage due to long-term current distribution. The long-term current statistics was assumed with a 3-parameter Weibull distribution. The fatigue damage was estimated for the span lengths obtained from the screening criteria for various conditions. Sample calculations show the effect of axial force for various boundary conditions.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.383-391
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• 2014

Long-term changes in the hydrological characteristics of a small forest watershed were examined using a master baseflow recession curve and the measured rainfall-runoff data from the experimental forest watershed in the measured years 2003-2011. The results of the study showed that the recession coefficient of direct runoff was lower than that of baseflow. In small forested watershed, the direct flow was lower than that of large scale watershed, flow due to its shorter period of occurrence. And baseflow was similar to large scale watershed's. A regression equation $y=0.7528e^{-0.022x}$($R^2=0.8938$, range 0.3~0.8 mm) was obtained using the master baseflow recession curve for the study period and the recession coefficient was calculated as K = 0.978. Changes between master baseflow recession curve and runoff showed great association and relevance such as increasing runoff was associated with the gentle slope of master baseflow recession curve and decreasing runoff was associated with the slope of master baseflow recession curve contrary. In the later years of the study period, the slope of the master baseflow recession curve appreciably became more gentle due to increases in baseflow. This suggests that the forested experimental watershed exhibit improved structural functioning of normal flood control and reduced occurrence of water shortage problems.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.313-316
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• 2004

Model selection is the process that sets up the regularization parameter in the support vector machine or regularization network by using the external methods such as general cross validation or L-curve criterion. This paper suggests that the regularization parameter can be obtained simultaneously within the learning process of neural networks without resort to separate selection methods. In this paper, extended kernel method is introduced. The relationship between regularization parameter and the bias term in the extended kernel is established. Experimental results show the effectiveness of the new model selection method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.64-74
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• 1997

A CELTHYM(CEll-based Long-term HYdrologic Model), a pre-processor and a post-processor that can be integrated with geographic information system(GIS) were developed to predict the stream flow from the small agricultural watershed on the daily basis. The CELTHYM calculates the direct runoff from a grid using SCS curve number method and then sum up all of cells with respect to a sub-catchment area belonged to a stream grid and integrated to an outlet. Base flow of a watershed outlet was computed by integrating of the base flow of each stream grid that was averaged the sub-catchment deep-percolation and calculated with the release rate. Two kind of water budget equation were used to compute the water balance in a grid that was classified into not paddy field and paddy field. One of the two equation is a soil water balance equation to account the soil moisture of the upland, forest and excluding paddy field grid. The other is a paddy water balance equation for the paddy field, calculating the ponding depth, the effective rainfall, the deep percolation and the evapotranspiration.

• Korea Trade Review
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• v.44 no.1
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• pp.17-30
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• 2019

This study is to investigate the effect of real exchange rate on bilateral trade balance between Korea and ASEAN 10 countries. Using quarterly data from 1991 to 2017 the paper analyzes whether or not the real depreciation of Korea's won could improve the trade balance in the short and long term. Based on Autoregressive Distributed Lag(ARDL) model, the empirical results show that trade balance, GDP, and real exchange rate are all cointegrated, representing the long-run relationship among variables. In the consideration of long-run relationship, the increases in ASEAN countries' GDP could have a negative impact and Korea's GDP positive impact on trade balance between Korea and ASEAN countries unexpectedly. For the main variable, the paper did not find the long-term effect of real exchange rate on the trade balance, for the short-term effect of the real exchange rate it was found that there exists the J-curve effect only in the case of Vietnam and Brunei. Therefore, these results imply that the intended policy concerning the exchange rate in the free-floating exchange rate system could be limited to improve the trade balance between Korea and ASEAN countries.

• Geomechanics and Engineering
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• v.28 no.2
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• pp.157-169
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• 2022

Preloading of soft clays is a common ground stabilization method for improvement of compressibility and the undrained shear strength. The waiting period under preload is a primary design criterion controlling the degree of improvement obtained. Upon unloading the overconsolidation attained with respect to actual loads defines the long term performance. This paper presents a laboratory study for investigation of creep behavior of Famagusta Bay alluvial soft soil preloaded under various effective stresses for analysis of long term performance based on the degree of overconsolidation. Traditional one-dimensional consolidation tests as well as modified creep tests are performed on reconstituted soft specimens. Compressibility parameters are precisely backcalculated using one dimensional consolidation theory and the coefficient of creep is determined using the traditional Cassagrande method as well as two modified methods based on log cycles of time and the inflection of the creep curve. The test results indicated that the long term creep can be successfully predicted considering the proposed method. The creep coefficients derived as part of this method can also be related to the recompression index (recompression index, swelling index) considering the results of the testing method adopted in this study.

• Journal of Preventive Medicine and Public Health
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• v.56 no.6
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• pp.495-503
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• 2023

Objectives: While older adults using community care services are known to be vulnerable for depression, community care utilization (CCU) may help to improve the mental health of these elderly. To date, however, it is much less clear how CCU affects depressive symptoms in the elderly population. This study focuses on the trajectory of depressive symptoms across years of CCU among older adults in Korea. Methods: Using the 2006-2019 Korean Welfare Panel Survey, this study is focused on elderly born in 1940 or earlier and selected 3281 persons for baseline interviews in 2006. This consisted of 35 800 person-year observations during a period of 14 years. Panel data analysis were employed to construct years of CCU. Results: After controlling for covariates, linear term of years using community care was negatively associated with depressive symptoms, but a quadratic term was positively significant. The trajectory of depressive symptoms across the years of CCU follows a U-shaped curve. Older adults in the first year of using community care reported the highest level of depressive symptoms. However, a significant and steady decrease in depressive symptoms was observed during the following 9 years of CCU, which then gradually increased. The level of depressive symptoms at the 14th year of using community care remains significantly lower than the level at the outset of its utilization. Conclusions: This finding implies that CCU could be beneficial for improving mental health among older adults.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.860-870
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• 2010

Long term monthly monitoring data showed that the water quality of streams flowing into Lake Paldang has been improved by various strategy for water. However, the effect of quality on Lake Paldang is still insufficient because of nonpoint source from watershed. In order to evaluate quantifying methods for pollution source and make a suggestion on improvements, Storm Water Management Model (SWMM) was constructed by using data set from the water quality and streamflow monitoring network in the Kyoungan watershed for Total Maximum Daily Loads (TMDLs). Load duration curve (LDC) based on the result of the Kyoungan watershed SWMM indicated that the water quality criterion on $BOD_5$ was often exceeded in up-stream than down-stream. From flowrate-load correlation curve, SS load significantly increased as streamflow increases. 75.3% of streamflow and 62.1% of $BOD_5$ loads is discharged especially in the zone of high flows, but monitoring data set didn't provide proper information about the conditions and the patterns associated with storm events. Therefore, it is necessary to acquire representative data set for comparing hydrograph and pollutograph through monitoring experimental watershed and to establish methods for quantifying point and nonpoint source pollutant loads.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.2 s.5
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• pp.85-93
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• 2002

This paper is to derive the Intensity-Duration-Frequency Curve at Kong-Ju area after estimating probable rainfall depths using Rainfall Frequency Atlas of Korea. It has been suggested that the probable rainfall intensity formulas should be classified by short and long term basis in this area. The coefficients of determination of the probable rainfall intensity formulas are calculated as high as 0.9924 through 0.9971. Four types of rainfall intensity formulas such as Talbot type, Sherman type, Japanese type, General type are considered to determine the best type for the Kong-Ju area. Sherman type applied in this study can be determined as the representative probable rainfall intensity formula in the area. Therefore the rainfall intensity formulas for the selected return period in this study provide valuable insight into the estimation of the rainfall intensity. The developed Intensity-Duration-Frequency Curve can be used to provide a better hydraulic design at Kong-Ju area.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.1 no.2
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• pp.11-20
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• 2006

Objectives: The aim of this study is to investigate clinical effects of Chuna treatment on the neck pain patient with hypolordotic cervical spine. Methods: From June 2006 to August 2006, 20 cases of neck pain patient with hypolordotic cervical spine were divided into 2 groups. Control group(n=10) was treated only acupuncture therapy, and sample group(n=10) was treated Chuna after acupuncture therapy same as control group. Degrees of pain were measured with Visual Analogue Scale(VAS), and the change of cervical curvature was assessed Depth of cervical curve, Method of Jochumsen, and Angle of cervical curve. Results: 1. After 3th and 5th treatment, there was statistical significance between control and sample group in VAS. 2. After 5th treatment, there was not statistical significance between control and sample group in Depth of cervical curve, Method of Jochumsen, and Angle of cervical curve. Conclusions: On treating the neck pain patient with hypolordotic cervical spine, Chuna treatment is more effective than only acupuncture therapy in reducing neck pain, but Chuna treatment for short-term is not more effective than only acupuncture therapy in restoring cervical curvature.