• Journal of the Korean Geotechnical Society
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• v.37 no.5
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• pp.47-63
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• 2021

Recently, the demand for three-dimensional (3D) underground maps from the perspective of digital twins and the demand for linkage utilization are increasing. However, the vastness of national geotechnical survey data and the uncertainty in applying geostatistical techniques pose challenges in modeling underground regional geotechnical characteristics. In this study, an optimal learning model based on multi-layer perceptron (MLP) was constructed for 3D subsurface lithological and geotechnical classification in Seoul, South Korea. First, the geotechnical layer and 3D spatial coordinates of each borehole dataset in the Seoul area were constructed as a geotechnical database according to a standardized format, and data pre-processing such as correction and normalization of missing values for machine learning was performed. An optimal fitting model was designed through hyperparameter optimization of the MLP model and model performance evaluation, such as precision and accuracy tests. Then, a 3D grid network locally assigning geotechnical layer classification was constructed by applying an MLP-based bet-fitting model for each unit lattice. The constructed 3D geotechnical layer map was evaluated by comparing the results of a geostatistical interpolation technique and the topsoil properties of the geological map.

• Journal of Korea Water Resources Association
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• v.55 no.3
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• pp.245-255
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• 2022

Evaluating the qualitative the qualitative process of water resources by using various indicators, as one of the most prevalent methods for optimal managing of water bodies, is necessary for having one regular plan for protection of water quality. In this study, zoning maps were developed on a yearly basis by collecting and reviewing the process, validating, and performing statistical tests on qualitative parameters҆ data of the Iranian aquifers from 1995 to 2020 using Geographic Information System (GIS), and based on Inverse Distance Weighting (IDW), Radial Basic Function (RBF), and Global Polynomial Interpolation (GPI) methods and Kriging and Co-Kriging techniques in three types including simple, ordinary, and universal. Then, minimum uncertainty and zoning error in addition to proximity for ASE and RMSE amount, was selected as the optimum model. Afterwards, the selected model was zoned by using Scholar and Wilcox. General evaluation of groundwater situation of Iran, revealed that 59.70 and 39.86% of the resources are classified into the class of unsuitable for agricultural and drinking purposes, respectively indicating the crisis of groundwater quality in Iran. Finally, for validating the extracted results, spatial changes in water quality were evaluated using the Groundwater Quality Index (GWQI), indicating high sensitivity of aquifers to small quantitative changes in water level in addition to severe shortage of groundwater reserves in Iran.

• Journal of Korea Water Resources Association
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• v.55 no.7
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• pp.545-556
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• 2022

It is recommended to use long-term hydrometeorological data for more than the service life of the hydraulic structures and water resource planning. For the purpose of expanding rainfall data, stochastic simulation models, such as Modified Bartlett-Lewis Rectangular Pulse (BLRP) and Neyman-Scott Rectangular Pulse (NSRP) models, have been widely used. The optimal parameters of the model can be estimated by repeatedly comparing the statistical moments defined through a combination of parameters of the probability distribution in the optimization context. However, parameter estimation using relatively small observed rainfall statistics corresponds to an ill-posed problem, leading to an increase in uncertainty in the parameter estimation process. In addition, as shown in previous studies, extreme values are underestimated because objective functions are typically defined by the first and second statistical moments (i.e., mean and variance). In this regard, this study estimated the parameters of the NSRP model using the objective function with the third moment and compared it with the existing approach based on the first and second moments in terms of estimation of extreme rainfall. It was found that the first and second moments did not show a significant difference depending on whether or not the skewness was considered in the objective function. However, the proposed model showed significantly improved performance in terms of estimation of design rainfalls.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1273-1283
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• 2022

Recently, forest fires have frequently occurred due to climate change, leading to human and property damage every year. The forest fire monitoring technique using remote sensing can obtain quick and large-scale information of fire-damaged areas. In this study, the Gangneung and Donghae forest fires that occurred in March 2022 were analyzed using the spectral band of Sentinel-2, the normalized difference vegetation index (NDVI), and the normalized difference water index (NDWI) to classify the affected areas of forest fires. The U-net based convolutional neural networks (CNNs) model was simulated for the fire-damaged areas. The accuracy of forest fire classification in Donghae and Gangneung classification was high at 97.3% (f₁=0.486, IoU=0.946). The same model used in Donghae and Gangneung was applied to Uljin and Samcheok areas to get rid of the possibility of overfitting often happen in machine learning. As a result, the portion of overlap with the forest fire damage area reported by the National Institute of Forest Science (NIFoS) was 74.4%, confirming a high level of accuracy even considering the uncertainty of the model. This study suggests that it is possible to quantitatively evaluate the classification of forest fire-damaged area using a spectral band and indices similar to that of the Compact Advanced Satellite 500 (CAS500-4) in the Sentinel-2.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.8
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• pp.331-338
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• 2022

Successor representation (SR) is a model of human reinforcement learning (RL) mimicking the underlying mechanism of hippocampal cells constructing cognitive maps. SR utilizes these learned features to adaptively respond to the frequent reward changes. In this paper, we evaluated the performance of SR under the context where changes in latent variables of environments trigger the reward structure changes. For a benchmark test, we adopted SR-Dyna, an integration of SR into goal-driven Dyna RL algorithm in the 2-stage Markov Decision Task (MDT) in which we can intentionally manipulate the latent variables - state transition uncertainty and goal-condition. To precisely investigate the characteristics of SR, we conducted the experiments while controlling each latent variable that affects the changes in reward structure. Evaluation results showed that SR-Dyna could learn to respond to the reward changes in relation to the changes in latent variables, but could not learn rapidly in that situation. This brings about the necessity to build more robust RL models that can rapidly learn to respond to the frequent changes in the environment in which latent variables and reward structure change at the same time.

• Analytical Science and Technology
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• v.19 no.5
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• pp.400-406
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• 2006

Hydrogen analysis by elastic recoil detection has been performed utilizing polyimide film as a reference sample of known hydrogen content assuming the soundness of ion beam current integration. However beam current integration at higher incidence angle is not reliable. Scattering yield per unit fluence by current integration which is normalized per unit path length decreases as the sample tilt angle is getting higher. Moreover because beam current integration at high tilt angle is incomplete, hydrogen evaluation is very risky by direct comparison of sequentially collected recoil spectra between reference and target sample. In this study, primary ion beam dose is determined by backscattering spectrum that is collected simultaneously with recoil spectrum instead of ion beam current integration in order to reduce uncertainty arising in the process of current integration and to enhance the reliability of quantitative analysis. Three test samples are selected $-7.6{\mu}m$ polyimide film, hydrogen implanted silicondioxide and Au deposited carbon wafer- and analyzed by two methods and compared.

• Asia Marketing Journal
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• v.8 no.1
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• pp.49-76
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• 2006

This study investigates the effect of market orientation of knowledge-based service suppliers on the sourcing process of service recipients. Focusing on a dyadic relationship between a supplier and a buyer, this study proposed a conceptual model of market orientation incorporating the antecedents and consequences of market orientation. This study empirically tested research hypotheses delineated from the conceptual framework. The present study revealed that the impact on the buyer's performance of the supplier's customer and competitor orientation turned out to be more influential than that of inter-departmental cooperation. Also these two dimensions of customer and competitor orientation played a positive role in reducing buyer's perceived risk and uncertainty related to the evaluation of services out-sourced. Interestingly enough, the supplier's perceived importance on the distance between the buyer and supplier remains important especially when the degree of buyer's market orientation is high. This finding is somewhat contrary to the fact that the geographic location of the buyer becomes less important for the internet-based B2B service providers. Based on the findings, this study suggested managerial implications and broadened the scope of academic research in the field of business services. Future research directions and the limitations of this study are also discussed.

• Journal of Korea Water Resources Association
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• v.57 no.2
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• pp.139-150
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• 2024

This study introduced a method of estimating water surface evaporation using the physical-based Penman combination equation (PCE) and the Penman wind function (PWF). A set of regression parameters in the PCE and PWF models were optimized by using the observed evaporation data for the period 2016-2017 in the Yongdam Dam watershed, and their effectiveness was explored. The estimated evaporation over the Deokyu Mountain flux tower demonstrated that the PWF method appears to have more improved results in terms of correlation, but both methods showed overestimation. Further, the PWF method was applied to the observed hydro-meteorological data on the surface of Yongdam Lake. The PWF method outperformed the PCE in the estimation of water surface evaporation in terms of goodness-of-fit measure and visual evaluation. Future studies will focus on a regionalization process which can be effective in estimating water surface evaporation for the ungauged area by linking hydrometeorological characteristics and regression parameters.

• Journal of Korean Home Economics Education Association
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• v.35 no.3
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• pp.117-133
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• 2023

This study investigates the perceptions, Stages of Concern (SoC), and Levels of Use (LoU) regarding process-based assessment among Home Economics (HE) teachers to determine the necessary support for its implementation in schools. Data were gathered from a survey administered to HE teachers. The results are as follows. First, HE teachers viewed process-based assessment favorably, valuing its multifaceted evaluation approach over result-based assessment. The feedback from process-based assessments was seen as an opportunity for reflection for both educators and students. While some teachers expressed uncertainty about the optimal timing of implementation, they generally demonstrated a sound understanding of the feedback concept within the assessment process. HE teachers were predominantly concerned with their own professional expertise and the learning outcomes of their students. The majority of HE teachers have utilized process-based assessments for at least one semester. None deemed it irrelevant to their practice or showed disinterest in its adoption. Those who had yet to implement it were either in the first(introduction) or the second(preparation) stages.

• Journal of Preventive Medicine and Public Health
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• v.33 no.3
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• pp.334-342
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• 2000

Objectives . This study was conducted in order to investigate the degree of recognition, acceptability, and altitude towards day surgery of patients who were hospitalized with diseases that were candidates for day surgery; in order to analyze the average length of stay for treatment of the ailments; and to analyze the percentage of patients who could be discharged on the same day after the surgery ,using the post-anesthesia discharge scoring system. Methods : Data was collected between February 1 and March 31, 1999 from 353 patients who received surgery for cataract, adenoid hypertrophy, inguinal hernia, strabismus, ptosis, cholelithiasis, hemorrhoid, or anal fistula, at a general hospital in Daegu city. The patients were interviewed and surveyed by a post-anesthesia discharge scoring system(PADS) in order to collect data on patient condition such as vital signs, activity and mental status, pain, nausea and vomiting, surgical bleeding, intake and output after the surgery. Results : Among the 353 patients, 52.7% were after of the day surgery and 52.7% were interested in day surgery. Of the respondents, 43.1% said 'my ailment was not serious and the surgery was simple' and 30.4% said 'according to my condition rest at home was desirable' as the reasons for wanting day surgery Alternatively, 56.5% of those declining day surgery said the 'uncertainty of staying home' was the reason. The greatest concern in discharging within 24 hours after surgery was a post-op emergency situation. On the other hand, the shortened hospitalization was the largest advantage of day surgery with 39.1% responding this way, followed by the savings in hospitalization costs (25.8%) and emotional stability (13.7%). The majority of those surveyed (47.6%) believed that discharge should be determined within 1-2 days after the surgery. The average hospital stay was 3.1 days for dischargeable ailments. Pain (45.6%), nausea and vomiting (10.5%), and headache (7.9%) were the common symptoms following surgery. The percentage of patients who were able to be discharged within 24 hours after surgery revealed 95.2% were dischargeable after approximately 3 hours, 99.2% dischargeable after 12 hours, and 100% dischargeable after 24 hours. Conclusions : According to the PADS score, the cataract extract and strabismus correction patients were eligible for day surgery and the further evaluation concerning the reason for delayed recovery of the other diseases is needed.