• Journal of Digestive Cancer Research
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• v.5 no.2
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• pp.86-90
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• 2017

Background: The aim of this study was to investigate clinicopathologic features of type 3 gastric neuroendocrine neoplasm (NEN) by treatment modality. Methods: The Korean Society of Gastrointestinal Cancer conducted the Korean Gastroenteropancreatic Neuroendocrine Tumor Registry, a retrospective registry database of gastroenteropancreatic neuroendocrine tumors from 16 hospitals in Korea. The normal serum gastrin level range was defined as <100 pg/mL, and gastric NEN patients with normal gastrin level were selected for analysis. Results: Among 358 patients with gastric NEN, 21 (5.9%) patients were classified with type 3 gastric NEN. The median age was 53 years (range 30-74). According to the WHO 2010 classification, 13 (61.9%) patients had grade 1, and 8 (38.1%) patients had grade 2 or 3. Endoscopic treatment was performed in 14 (66.7%) patients, and surgery was performed in 7 (33.3%) patients. The tumor size was smaller in the endoscopic treatment group than in the surgery group (0.6 cm vs 1.3 cm, p=0.006). After treatment, there was one recurrence in the surgery group. Conclusion: In small size Type 3 gastric NEN, endoscopic treatment was associated with a good prognosis, compared to surgery. Thus, endoscopic treatment can be used an alternative modality in selected cases of type 3 gastric NEN.

• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.229-237
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• 2023

The use of artificial sources such as explosives and mechanical vibrations for seismic exploration in urban areas poses challenges, as the vibrations and noise generated can lead to complaints. As an alternative to artificial sources, the surface waves generated by traffic noise can be used to investigate the subsurface properties of urban areas. However, traffic noise takes the form of plane waves moving continuously at a constant speed. To apply existing surface wave processing/inversion techniques to traffic noise, the recorded data need to be transformed into a virtual shot gather format using seismic interferometry. In this study, various seismic interferometry methods were applied to traffic noise data, and the optimal method was derived by comparing the results in the Radon and F-K domains. Additionally, the data acquired using various receiver arrays were processed using seismic interferometry, and the results were compared and analyzed to determine the most optimal receiver array direction for exploration.

• Journal of Life Science
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• v.33 no.11
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• pp.876-886
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• 2023

In some cases of head and neck cancers (HNC), surgical interventions may result in the loss of organs and/or changes to their functions, thereby significantly affecting the patient's quality of life. As a result, the surgical treatment of HNC patients is often limited to specific cases, and alternative treatment modalities, such as chemotherapy, are considered. However, serious adverse effects caused by chemotherapy, such as severe nausea and vomiting, necessitate the need for the development of adjunctive methods to minimize patient suffering. Chuanxiong, Ligusticum chuanxiong (L. chuanxiong), is a natural herb used in Eastern medicine to treat cerebrovascular disorders and headaches. This study aimed to predict the effect and potential of L. chuanxiong as an auxiliary anticancer drug through network-based pharmacology and molecular docking analysis. The study results showed that 40 out of 41 genes of L. chuanxiong shared common targets of HNC and their proteins could be used to target HNC cells to prevent cancer progression. The results of the functional enrichment analysis confirmed that L. chuanxiong is associated with the neuroactive-ligand metabolism and neurotransmitter pathways, indicating its potential medicinal value as an adjuvant in HNC treatment. Lastly, our findings demonstrated that the active ingredient of L. chuanxiong, (Z)-Ligustilide, has the ATP binding site of heat shock protein 90, a protein known to promote the activation of cancer cells. These results suggest that L. chuanxiong is a promising candidate for developing auxiliary anticancer drugs, and further research could potentially lead to the discovery of newer and safer anti-cancer agents.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.542-549
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• 2023

Since the growing interest in surrogate modeling, there has been continuous research aimed at simulating nonlinear chemical processes using data-driven machine learning. However, the opaque nature of machine learning models, which limits their interpretability, poses a challenge for their practical application in industry. Therefore, this study aims to analyze chemical processes using Explainable Artificial Intelligence (XAI), a concept that improves interpretability while ensuring model accuracy. While conventional sensitivity analysis of chemical processes has been limited to calculating and ranking the sensitivity indices of variables, we propose a methodology that utilizes XAI to not only perform global and local sensitivity analysis, but also examine the interactions among variables to gain physical insights from the data. For the ammonia synthesis process, which is the target process of the case study, we set the temperature of the preheater leading to the first reactor and the split ratio of the cold shot to the three reactors as process variables. By integrating Matlab and Aspen Plus, we obtained data on ammonia production and the maximum temperatures of the three reactors while systematically varying the process variables. We then trained tree-based models and performed sensitivity analysis using the SHAP technique, one of the XAI methods, on the most accurate model. The global sensitivity analysis showed that the preheater temperature had the greatest effect, and the local sensitivity analysis provided insights for defining the ranges of process variables to improve productivity and prevent overheating. By constructing alternative models for chemical processes and using XAI for sensitivity analysis, this work contributes to providing both quantitative and qualitative feedback for process optimization.

• Korea Trade Review
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• v.45 no.4
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• pp.137-152
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• 2020

The increase in national income, the expansion of transportation network, the increase in leisure time, and the influx of foreign tourists in the era of internationalization, the influx of the outside population of Jeju region increased rapidly until 2020. However, the corona 19 (Covid-19) incident that began in January 2020 has hit the entire industry, and the tourism industry in Jeju has also been greatly damaged. However, in the second half of 2020, with some calming of the Corona 19 situation and difficult to leave overseas, the number of visitors to Jeju Island is increasing again as Koreans choose Jeju Island as their domestic tourism. This study analyzed the capacity of Jeju's external population based on the Contingent Valuation Method, and based on this, attempted to suggest policy recommendations for Jeju. The size of accommodations such as the density of visitors, toilets, and rest areas were excluded from consideration, and the level of securing the parking lot already exceeded the capacity, and the rate of securing the parking lot was 93.4%. In the case of accommodation, the total number of available rooms is 88,691, even if one guest per room is assumed, which is 32,372,215 per year, which is sufficient in terms of visitor capacity. To analyze the aspects of psychological capacity, this study analyzed whether the residents are feeling psychological discomfort through three methods of road congestion, garbage disposal, and sewage treatment through Contingent Valuation Method. However, the inconvenience caused by the increase of visitors and the effect of continuous population influx is working in combination, and it has the limitation that the effects of these independent factors cannot be specifically separated. As a result of the study, discomfort has already been recognized in terms of psychological capacity among the factors of capacity, and it was estimated that a cost of about 45 billion won per year was incurred as a result of deriving psychological costs through Contingent Valuation Method. In the future, a policy review is needed to resolve or maintain the perception of this discomfort through continuous management. Accordingly, it is necessary to recognize that the increase of visitors leads to the psychological discomfort of the residents, and to seek a policy alternative that can simultaneously increase the number of visitors and the comfort of the residence.

• Tunnel and Underground Space
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• v.33 no.6
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• pp.435-444
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• 2023

In the licensing application for the deep geological disposal system of high-level radioactive waste in Finland, the disposal tunnel backfilling has been changed from the block/pellet (for the construction) to the granular type (for the operation). Accordingly, for establishing the design concept for backfilling, it is necessary to examine applicability to the domestic facility through analyzing problems of the existing method and improvements in the alternative design. In this paper, we first reviewed the principal studies conducted for changing the backfill method in the licensing process of the Finnish facility, and identified the expected problems in applying the block/pellet backfill method. In addition, we derived the evaluation factors to be considered in terms of technical and operational aspects for the backfilling solution, and then conducted a comparative analysis for two types of backfill methods. This analysis confirmed the overall superiority of the design change. It is expected that these results could be utilized as the technical basis for deriving the optimum design plan in development process of the Korean-specific deep disposal facility. However, applicability should be reviewed in advance based on the latest technical data for the detailed evaluation factors that must be considered for selecting the backfilling method.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.1
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• pp.229-249
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• 2022

This paper investigates machine learning models for predicting the designation of administrative issues in the KOSDAQ market through various techniques. When a company in the Korean stock market is designated as administrative issue, the market recognizes the event itself as negative information, causing losses to the company and investors. The purpose of this study is to evaluate alternative methods for developing a artificial intelligence service to examine a possibility to the designation of administrative issues early through the financial ratio of companies and to help investors manage portfolio risks. In this study, the independent variables used 21 financial ratios representing profitability, stability, activity, and growth. From 2011 to 2020, when K-IFRS was applied, financial data of companies in administrative issues and non-administrative issues stocks are sampled. Logistic regression analysis, decision tree, support vector machine, random forest, and LightGBM are used to predict the designation of administrative issues. According to the results of analysis, LightGBM with 82.73% classification accuracy is the best prediction model, and the prediction model with the lowest classification accuracy is a decision tree with 71.94% accuracy. As a result of checking the top three variables of the importance of variables in the decision tree-based learning model, the financial variables common in each model are ROE(Net profit) and Capital stock turnover ratio, which are relatively important variables in designating administrative issues. In general, it is confirmed that the learning model using the ensemble had higher predictive performance than the single learning model.

• Information Systems Review
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• v.24 no.1
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• pp.21-37
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• 2022

Drug repositioning, one of the methods of developing new drugs, is a useful way to discover new indications by allowing drugs that have already been approved for use in people to be used for other purposes. Recently, with the development of machine learning technology, the case of analyzing vast amounts of biological information and using it to develop new drugs is increasing. The use of machine learning technology to drug repositioning will help quickly find effective treatments. Currently, the world is having a difficult time due to a new disease caused by coronavirus (COVID-19), a severe acute respiratory syndrome. Drug repositioning that repurposes drugsthat have already been clinically approved could be an alternative to therapeutics to treat COVID-19 patients. This study intends to examine research trends in the field of drug repositioning using machine learning techniques. In Pub Med, a total of 4,821 papers were collected with the keyword 'Drug Repositioning'using the web scraping technique. After data preprocessing, frequency analysis, LDA-based topic modeling, random forest classification analysis, and prediction performance evaluation were performed on 4,419 papers. Associated words were analyzed based on the Word2vec model, and after reducing the PCA dimension, K-Means clustered to generate labels, and then the structured organization of the literature was visualized using the t-SNE algorithm. Hierarchical clustering was applied to the LDA results and visualized as a heat map. This study identified the research topics related to drug repositioning, and presented a method to derive and visualize meaningful topics from a large amount of literature using a machine learning algorithm. It is expected that it will help to be used as basic data for establishing research or development strategies in the field of drug repositioning in the future.

• Journal of Wetlands Research
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• v.26 no.1
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• pp.32-40
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• 2024

The purpose of this study is to collect basic information about Narrow-mouthed Toad (Kaloula borealis) by analyzing the morphological characteristics of Narrow-mouthed Toad (Kaloula borealis) caught in pitfall traps. The study site is in Godeok-dong, Gangdong-gu, Seoul, and a total of 1,063 individuals were captured using pitfall traps for a total of four years from July 2016 to November 2020. Narrow-mouthed Toad (Kaloula borealis) were classified into adult and immature individuals based on length (SVL), and differences in sex ratio and shape were confirmed for adults. As a result, all adult males had a pair of white bands observed in the abdomen, and females had eggs identified in the abdomen. Through previous studies, a pair of white bands on the abdomen were determined to be male gonads, and were also confirmed in some immature individuals. The sex of the Narrow-mouthed Toad (Kaloula borealis) could be distinguished by the presence or absence of a pair of white bands located on the abdomen, and it is believed that this can be used as a sex classification method that can be confirmed in the field. During the study period, the adult sex ratio was confirmed to be 697 male (65.57%) and 366 female (34.43%), with more males. It is expected that this method of sex ratio and male/female sex ratio will be used not only for species restoration and monitoring of migration and alternative habitats due to development, but also as basic data for various ecological studies.

• Korean Journal of Radiology
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• v.25 no.3
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• pp.289-300
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• 2024

Objective: To prospectively evaluate the outcomes of ultrasound (US)-guided radiofrequency ablation (RFA) in tertiary hyperparathyroidism (THPT). Materials and Methods: Patients with THPT underwent RFA between September 2017 and January 2022. Laboratory parameters, including serum intact parathyroid hormone (iPTH) levels, were monitored for 48 months after RFA and compared with the levels at baseline. Complications related to RFA and changes in hyperparathyroidism-related clinical symptoms were recorded before and after RFA. Results: A total of 42 patients with THPT were recruited for this study. Ultimately, 36 patients with renal failure and 2 patients who underwent successful renal transplantation (male:female, 17:21; median age, 54.5 years) were enrolled. The follow-up time was 21.5 ± 19.0 months in the 36 patients with renal failure. In these 36 patients, iPTH levels were significantly decreased to 261.1 pg/mL at 48 months compared with the baseline value of 1284.9 pg/mL (P = 0.012). Persistent hyperparathyroidism, defined as iPTH levels maintained at > 585.0 pg/mL for 6 months after treatment, occurred in 4.0% of patients (1/25). Recurrent hyperparathyroidism, defined as iPTH levels > 585.0 pg/mL after 6 months, were 4.0% (1/25) and 0.0% (0/9) at 6 months and 4 years after treatment, respectively. In two patients with THPT after successful renal transplantation, iPTH decreased from the baseline value of 242.5 and 115.9 pg/mL to 171.0 and 62.0 pg/mL at 6 months after treatment. All complications resolved within 6 months of ablation without medical intervention, except in 10.5% (4/38) patients with permanent hypocalcemia. The overall symptom recovery rate was 58.8% (10/17). The severity scores for bone pain, arthralgia, and itchy skin associated with hyperparathyroidism improved after treatment (P < 0.05). Conclusion: US-guided RFA is an effective and safe alternative to surgery in the treatment of patients with TPTH and improves hyperparathyroidism-related clinical symptoms.