• Journal of Wetlands Research
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• 제23권2호
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• pp.173-182
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• 2021

It is important to extract and assess low-flow recession characteristics for water resources management in the upper reaches of a stream. It is difficult to express the groundwater flow recession characteristics for streamflow synthetically. The linear recession model has been widely used by baseflow recession analysis for reason of simplicity and convenience, but recent studies show that nonlinear recession models fit well, and the relationship between the reservoir storage of shallow unconfined aquifers and the groundwater discharge was to be identified as nonlinear in the literature based on the analysis of numerous streamflow recession curves. The objective of the study is to decode these nonlinear characteristics, including evaporation loss, storage, and recharge of groundwater using streamflow. By analyzing the observed time series of streamflow from the study area, which is the Pyeongchang River basin in Korea, the main components of the underlying groundwater balance, namely, discharge, evaporation loss, storage, and recharge, can be identified and quantified. As a result of the study, depletion of groundwater by evapotranspiration losses through the water uptake of tree roots was found to bias the recession curves and the estimated reservoir parameters. The seasonality of both rainfall and potential evaporation, analysis of the recession curves, stratified according to time of the year, allowed the quantification of evapotranspiration loss as a function of a calendar month and stored groundwater storage.

• Journal of Korea Water Resources Association
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• 제35권4호
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• pp.375-384
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• 2002

This study is to suggest a method to estimate the design low-flow based on the runoff hydrology. The recession time model to transform a return period into the recession time is derived under the similarity between dry spell and low-flow runoffs event. The proposed recession model can be applied to the gaging station and the ungaged outlet. This recession time model contains the parameters: for climate conditions, watershed characteristics, and runoff characteristics etc. And the recession model is composed of the parameters which are initial discharge and recession constant. This model is applied to the Yongdam gaging station and the other temporary gaging station. Consequently, it is proved that this model can be used for an alternative practice to estimate the design low-flow at the gaging station with short-term runoff data or the ungaged outlet.

• Safety and Health at Work
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• 제3권4호
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• pp.294-297
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• 2012

Previous studies on the vast increase in suicide mortality in Southeast Asia have indicated that suicide rates increase in parallel with a rise in unemployment or during periods of economic recession. This paper examines the effects of economic recession on suicidal rates amongst agriculture, fisheries, and forestry workers in Korea. Monthly time-series gross domestic product (GDP) data were linked with suicidal rates gathered from the cause of death records between1993-2008. Data were analyzed using generalized additive models to analyze trends, while a polynomial lag model was used to assess the unconstrained time lag effects of changes in GDP on suicidal rate. We found that there were significant inverse correlations between changes in GDP and suicide for a time lag of one to four months after the occurrence of economic event. Furthermore, it was evident that the overall relative risks of suicide were high enough to bring about social concern.

• Journal of The Korean Society of Clinical Toxicology
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• 제3권1호
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• pp.33-39
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• 2005

Purpose: Nowadays the Korean society is in the center of time of the social change. Because of dissociation of traditional family, IMF (International Monetary Fund) crisis and economic recession, the mortality rate of suicidal attempts are increasing annually. The majority of suicidal attempts were by poisoning considering the characteristics of korean society. Therefore we studied to find out the characteristics of suicidal poisoning before and after social economic stress, and to suggest the direction for the proper management. Methods: We reviewed medical records of 547 patients of suicide by poisoning who visited the emergency medical centers of St. Mary's hospitals from 1997 to 2004. For the annual trends analysis, we analyzed the demographic and toxicologic data of these patients compared with before and after IMF crisis (1998) and the economic recession ($2003\~2004$). Results: At the time of IMF and the economic recession, the number of suicidal poisoning increased, especially in fifth decade. The refusal rate of toxicological emergency treatment increased. Also the mortality rate and the admission rate to ICU (Intensive Care Unit) increased during the same period. In the result of the comparison analysis, clinical severity and mortality of social problem group were higher. However they couldn't be treated appropriately because of financial problem and the family indifference. Conclusion: At the economic recession period, the severity of suicidal poisoned patients was high. But the refusal rate of toxicologic treatment also increased, so the patients had lost the chance for proper toxicologic treatment. Therefore they would be supported by medical institution and public health.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제46권9호
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• pp.735-741
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• 2018

In this paper, the surface recession of ablative materials was quantitatively analyzed using a high-speed camera and a three-dimensional profilometer. The ablation tests of the graphite and carbon/phenolic composite samples were performed using a 0.4 MW arc-heated wind tunnel for simulating the atmospheric re-entry environment. The real-time images during the ablation test were captured by the high-speed camera, and analyzed to calculate the surface recession and recession rate. Also, the surface data of samples were obtained using a three-dimensional profilometer, and the surface recession was precisely calculated from the difference of height between the surface data before and after the test. It is effective to complement the two measurement results in the comprehensive analysis of surface recession phenomena.

• Journal of Periodontal and Implant Science
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• 제48권6호
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• pp.395-404
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• 2018

Purpose: The purpose of this study was to propose a technique for periodontal biotype modification through thickening of the entire facial aspect using a volume-stable collagen matrix and autogenous subepithelial connective tissue graft (CTG) for the treatment of gingival recession. Methods: Four systemically healthy patients showing Miller class I or class II gingival recession in the mandibular incisor area were included in this study. Full-mouth scaling and root planing procedures were performed at least 4 weeks prior to periodontal plastic surgery. A split-thickness flap with a horizontal intrasulcular incision and 2 vertical incisions was used in cases 1-3, and the modified tunnel technique was used in case 4 for coronal advancement of the mucogingival complex. After the exposed root surfaces were debrided thoroughly, double-layered volume-stable collagen matrix was placed on the apical part of the recession and a subepithelial CTG harvested from the palatal area was placed on the coronal part. The amount of root coverage at 3 months postoperatively was evaluated in cases 1-3, and facio-lingual volumetric changes were analyzed in cases 1 and 2. Results: Healing was uneventful in all 4 cases and complete root coverage was shown in cases 1-3. In case 4, reduction of gingival recession was observed at 3 months after surgery. In cases 1 and 2, a comparison of stereolithographic files from the preoperative and postoperative time points demonstrated that the entire facio-lingual volume had increased. Conclusions: The surgical technique suggested herein, using a volume-stable collagen matrix and autogenous subepithelial CTG, may be an effective method for periodontal biotype modification through thickening of the entire facial aspect for the treatment of gingival recession.

• Korean Journal of Agricultural and Forest Meteorology
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• 제7권1호
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• pp.78-90
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• 2005

The spatial and temporal distribution of soil moisture was characterized from soil moisture data through the intensive monitoring using Time Domain Reflectometry (TDR). The recession of soil moisture after a rainfall event was characterized and the empirical equation was used in the recession curve analysis. Recession analysis provides features of soil moisture variation such as recharge and stability depending upon locations of monitoring. The wetness index was useful for explaining spatial and temporal distributions of soil moisture and recession characteristics at hillslope scale.

• Journal of the Korean Society of Clothing and Textiles
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• 제39권5호
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• pp.755-764
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• 2015

This study investigates if the relationships between hemline and macro-economic factors (rGDP, recession, and unemployment) are still applicable as well as analyzes time lags that reflect economic factors on the hemline index using U.S. data. The hemline theory and fashion cyclical theory were applied to propose the relationships studied. The data for the hemline measurements of women's day-wear were obtained from US Vogue spring and fall editions from 1950 to 2014. Data were standardized by dividing the length from shoulder to hemline by the length from the shoulder to ankle. I aggregated 2260 samples and hemline data to create a yearly average. This study used OLS of Stata 13 program to explore the relationship between macro-economic factors and hemline. The main findings were the recession and unemployment influenced hemline length for four years in a positive direction. Furthermore, the effects of previous recession and unemployment on the current hemline were very close to the significant level respectively. This finding supports the hemline theory in that a recessionary economy is related to longer hemlines and hemlines become shorter in flourishing economic periods.

• The Journal of the Korea Contents Association
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• 제18권9호
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• pp.366-374
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• 2018

In this paper the relationship between the business performance and the importance perception of management activities is analyzed. The analysis is conducted by dividing the analysis time-frame into before and after the economic recession. In addition, we consider the type of industry and the type of government support policy that the companies participate in. According to the results, the management activities, such as the introduction of domestic external technologies and the release of new products, are to have a significant impact on business performance for both before and after the economic recession. The introduction of foreign external technologies is significant before the economic recession, but after the economic recession the fund raising activity is shown to be significant. Management activities that affect business performance of large/small businesses, IT/non-IT companies, high/low R&D firms and the companies participated in various government support policies are different. In other words, it can be found that the support of management activities that can enhance performance should be done in an appropriate way considering the characteristics of the company rather than being provided to all companies in common.

• The Journal of the Korea Contents Association
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• 제18권10호
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• pp.498-506
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• 2018

Considering that firms' view on R&D activities may differ depending on the economic situation, in this paper, R&D policies that significantly affect the business performance are identified. The analysis is conducted by dividing the analysis time-frame into before and after the economic recession. In addition, we analyze by considering the type of industry, the proportion of R&D investment, and the type of government support policy that the companies participate in. According to the results of the empirical analysis, the provision of global market and technology information is recognized to give a significant impact on business performance for both before and after the economic recession. It is shown that recognizing the importance of 'supporting self-technology development', 'enhancing technical cooperation with foreign countries', and 'enhancing the contract and intellectual property protection system' that had significant effects before the recession did not significantly affect the business performance after the recession. The analysis results could give meaningful implications to the government for deciding which R&D activities should be supported.