• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.31-40
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• 2009

This paper presents a new approach of risk evaluation method for the reinforced slopes. In order to perform this study, the existing stability and risk evaluation methods are reviewed and analysed in terms of rainfall, ground condition, and drain conditions. According to the characteristic of the reinforced slopes improved by internal and external reinforcement, the nineteen influence factors are determined in order to develop new risk analysis model based on 'Interaction matrix' approach suggested by Hudson (1991). Using new approach of slope risk analysis model, the weighting values for interaction factors are analysed and determined. Based on new slope risk evaluation approach, the slope risk index, namely SRI (Slope Risk Index) is developed in this study to apply the evaluation of the reinforced slopes. In order to verify the SRI, a total of 15 cases are studied and analysed. The analysed results are compared and evaluated. According to the results, it is deduced that new slope risk evaluation method (SRI approach) IS very useful and practically a reliable method to evaluate the existing slopes.

• The Korean journal of internal medicine
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• v.39 no.1
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• pp.110-122
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• 2024

Background/Aims: Due to limited real-world evidence on the association between time to presentation (T2P) and outcomes following acute myocardial infarction and diabetes (AMI-DM), we investigated the characteristics of patients with AMI-DM and their outcomes based on their T2P. Methods: 4,455 patients with AMI-DM from a Korean nationwide observational cohort (2011-2015) were divided into early and late presenters according to symptom-to-door time. The effects of T2P on three-year all-cause mortality were estimated using inverse probability of treatment weighting (IPTW) and survival analysis. Results: The incidence of all-cause mortality was consistently higher in late presenters than in early presenters (11.4 vs. 17.2%; p < 0.001). In the IPTW-adjusted dataset, the incidence of all-cause mortality was numerically higher in late presenters than in early presenters (9.1 vs. 12.4%; p = 0.072). In the survival analysis, the cumulative incidence of all-cause mortality was significantly higher in late presenters than in early presenters before and after IPTW. In the subgroup with ST-elevation myocardial infarction, late presenters had a higher incidence of cardiac death than early presenters before (4.8 vs. 10.5%; p < 0.001) and after IPTW (4.2 vs. 9.7%; p = 0.034). In the initial glycated hemoglobin (HbA1c)-stratified analysis, these effects were attenuated in patients with HbA1c ≥ 9.0% before (adjusted hazard ratio [HR]: 1.45, 95% confidence interval [CI]: 0.80-2.64) and after IPTW (adjusted HR: 0.82, 95% CI: 0.40-1.67). Conclusions: Late presentation was associated with higher mortality in patients with AMI-DM; therefore, multifaceted and systematic interventions are needed to decrease pre-hospital delays.

• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.543-551
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• 2023

Snow is an essential climate factor that affects the climate system and surface energy balance, and it also has a crucial role in water balance by providing solid water stored during the winter for spring runoff and groundwater recharge. In this study, statistical analysis of Local Data Assimilation and Prediction System (LDAPS), Modern.-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), and ERA5-Land snow depth data were used to evaluate the applicability in South Korea. The statistical analysis between the Automated Synoptic Observing System (ASOS) ground observation data provided by the Korea Meteorological Administration (KMA) and the reanalysis data showed that LDAPS and ERA5-Land were highly correlated with a correlation coefficient of more than 0.69, but LDAPS showed a large error with an RMSE of 0.79 m. In the case of MERRA-2, the correlation coefficient was lower at 0.17 because the constant value was estimated continuously for some periods, which did not adequately simulate the increase and decrease trend between data. The statistical analysis of LDAPS and ASOS showed high and low performance in the nearby Gangwon Province, where the average snowfall is relatively high, and in the southern region, where the average snowfall is low, respectively. Finally, the error variance between the four independent snow depth data used in this study was calculated through triple collocation (TC), and a merged snow depth data was produced through weighting factors. The reanalyzed data showed the highest error variance in the order of LDAPS, MERRA-2, and ERA5-Land, and LDAPS was given a lower weighting factor due to its higher error variance. In addition, the spatial distribution of ERA5-Land snow depth data showed less variability, so the TC-merged snow depth data showed a similar spatial distribution to MERRA-2, which has a low spatial resolution. Considering the correlation, error, and uncertainty of the data, the ERA5-Land data is suitable for snow-related analysis in South Korea. In addition, it is expected that LDAPS data, which is highly correlated with other data but tends to be overestimated, can be actively utilized for high-resolution representation of regional and climatic diversity if appropriate corrections are performed.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.1
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• pp.50-60
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• 2014

The purpose of this study is to identify characteristics and improvements of the climate change vulnerability analysis methods to build a safe city from disasters. For this, an empirical analysis on sea level rise disasters was performed focusing on Heaundae-gu in Busan. For the analysis, Census output areas and Dongs were set as analysis unit and their disaster vulnerability was analyzed. Improvements were reviewed through the comparison and review of analysis process and results. According to analysis results, Modifiable Areal Unit Problem(MAUP) which gives different results according to aggregate unit occurs. Improvements were induced by analysis process, and it was found that in spatial unit setting stage that becomes the base of analysis, analysis unit adjustment, score computation method adjustment, and clearer analysis method for each disaster type would be needed. In analysis execution stage, it was thought that weighting according to variables, diversification of variables, and exclusion of subjective analysis selection method would be needed. It is expected that accurate the total disaster vulnerability analysis will be the base for the improvement of efficiency in urban resilience responding to future weather changes.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.600-607
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• 2010

In 2008, multiple episodes of large-scale transport of natural airborne particles and anthropogenically affected particles from different sources in the East Asian continent were identified in the National Oceanic and Atmospheric Administration (NOAA) satellite RGB-composite images and the mass concentrations of ground level particulate matters. To analyze the aerosol size distribution during the large-scale transport of atmospheric aerosols, both aerosol optical depth (AOD; proportional to the aerosol total loading in the vertical column) and fine aerosol weighting (FW; fractional contribution of fine aerosol to the total AOD) of Moderate resolution Imaging Spectroradiometer (MODIS) aerosol products were used over the East Asian region. The six episodes of massive natural airborne particles were observed at Cheongwon, originating from sandstorms in northern China, Mongolia and the loess plateau of China. The $PM_{10}$ and $PM_{2.5}$ stood at 70% and 16% of the total mass concentration of TSP, respectively. However, the mass concentration of $PM_{2.5}$ among TSP increased as high as 23% in the episode in which they were flowing in by way f the industrial area in east China. In the other five episodes of anthropogenically affected particles that flowed into the Korean Peninsula from east China, the mass concentrations of $PM_{10}$ and $PM_{2.5}$ among TSP reached 82% and 65%, respectively. The average AOD for the large-scale transport of anthropogenically affected particle episodes in the East Asian region was measured at $0.42{\pm}0.17$ compared with AOD ($0.36{\pm}0.13$) for the natural airborne particle episodes. Particularly, the regions covering east China, the Yellow Sea, the Korean Peninsula, and the east Korean sea were characterized by high levels of AOD. The average FW values observed during the event of anthropogenically affected aerosols ($0.63{\pm}0.16$) were moderately higher than those of natural airborne particles ($0.52{\pm}0.13$). This observation suggests that anthropogenically affected particles contribute greatly to the atmospheric aerosols in East Asia.

• Korean Journal of Psychosomatic Medicine
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• v.31 no.2
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• pp.108-117
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• 2023

Objectives : Somatic symptom disorder (SSD) is characterized by the manifestation of a variety of physical symptoms, but little is known about differences in autonomic nervous system activity according to symptom severity, especially within patient groups. In this study, we examined differences in heart rate variability (HRV) across symptom severity in a group of SSD patients to analyze a representative marker of autonomic nervous system changes by symptoms severity. Methods : Medical records were retrospectively reviewed for patients who were diagnosed with SSD based on DSM-5 from September 18, 2020 to October 29, 2021. We applied inverse probability of treatment weighting (IPTW) methods to generate more homogeneous comparisons in HRV parameters by correcting for selection biases due to sociodemographic and clinical characteristic differences between groups. Results : There were statistically significant correlations between the somatic symptom severity and LF (nu), HF (nu), LF/HF, as well as SD1/SD2 and Alpha1/Alpha2. After IPTW estimation, the mild to moderate group was corrected to 27 (53.0%) and the severe group to 24 (47.0%), and homogeneity was achieved as the differences in demographic and clinical characteristics were not significant. The analysis of inverse probability weighted regression adjustment model showed that the severe group was associated with significantly lower RMSSD (β=-0.70, p=0.003) and pNN20 (β=-1.04, p=0.019) in the time domain and higher LF (nu) (β=0.29, p<0.001), lower HF (nu) (β=-0.29, p<0.001), higher LF/HF (β=1.41, p=0.001), and in the nonlinear domain, significant differences were tested for SampEn15 (β=-0.35, p=0.014), SD1/SD2 (β=-0.68, p<0.001), and Alpha1/Alpha2 (ß=0.43, p=0.001). Conclusions : These results suggest that differences in HRV parameters by SSD severity were showed in the time, frequency and nonlinear domains, specific parameters demonstrating significantly higher sympathetic nerve activity and reduced ability of the parasympathetic nervous system in SSD patients with severe symptoms.

• Journal of Gifted/Talented Education
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• v.27 no.1
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• pp.17-35
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• 2017

The purpose of this study is to analyze the learning objectives characteristics of educational programs of centers for the university affiliated science-gifted education using semantic network analysis, we examined the applicability of semantic network analysis in analyzing learning objectives by comparing the results of analysis with Bloom's revised taxonomy. For this purpose, 702 learning objectives presented in 169 science subjects were selected as subjects to be analyzed. After classifying and coding the learning objectives according to Bloom's revised taxonomy, we conducted a semantic network analysis to investigate the relationship between learning objectives. The results of the analysis are as follows. First, we looked at the number of learning objectives used for each subject, and about 3 elementary school levels and about 6 middle school levels were used. Second, the knowledge dimension such as 'factual and conceptual knowledge' and cognitive process dimension such as 'remember', 'understand', and 'create' was high regardless of the research method and school level. Third, the results of analysis based on the weighting through the semantic network analysis method, the elementary school level emphasize activities th be applied to the actual experimental process through learning about scientific facts, while the middle school level emphasize the understanding of scientific facts and concepts themselves. As a result, it can be seen that the semantic network analysis can analyze characteristics of various learning objectives rather than the conventional simple statistical analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1773-1785
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• 1997

The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.

• Journal of Korea Multimedia Society
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• v.14 no.11
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• pp.1467-1477
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• 2011

This paper proposes a HPPS(Hybrid Preference Prediction System) design using the analysis of user profile and of the similarity among users precisely to predict the preference for custom-tailored service. Contrary to the existing NBCFA(Neighborhood Based Collaborative Filtering Algorithm), this paper is designed using these following rules. First, if there is no neighbor's commodity rating value in a preference prediction formula, this formula uses the rating average value for a commodity. Second, this formula reflects the weighting value through the analysis of a user's characteristics. Finally, when the nearest neighbor is selected, we consider the similarity, the commodity rating, and the rating frequency. Therefore, the first and second preference prediction formula made HPPS improve the precision by 97.24%, and the nearest neighbor selection method made HPPS improve the precision by 75%, compared with the existing NBCFA.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.19-34
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• 2018

This study analyzed specific ports' marketing strategies through interviews and, using fuzzy TOPSIS methodology, derived marketing strategies for the Incheon and Pyeongtaek-Dangjin ports by comparing them with the Busan port. Previous studies had concentrated on the Busan port, and the majority of these studies analyzed the present conditions and suggested 4P strategies using a marketing mix. After weighting all of the respondents' answers, the results show that among all marketing strategies, incentive provisions ranked the highest, followed by the intermediary role between the relevant agencies and companies, and last- the agent system for establishing local networks. The fuzzy TOPSIS analysis results showed that the Busan port had the best marketing performance. The most sensitive strategies, based on the sensitivity analysis, were the intermediary role between relevant agencies and companies in the Incheon port, and the incentive provision in Pyeongtaek-Dangjin port. The implications of this study are that the port management agencies' actual marketing strategies were similar to the marketing promotion strategies suggested by previous research, and thus, each port's marketing targets and their characteristics should be clearly defined.