• The Korean Journal of Pain
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• v.35 no.1
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• pp.4-13
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• 2022

Changes in diagnostic criteria, for example, the various International Classification of Headache Disorders criteria, would lead to changes in the outcomes of epidemiological studies. International Classification of Headache Disorders-1 was based mainly on expert opinion, yet most of the diagnostic criteria were reliable and valid, but it did not include chronic migraine. In its second version, the classification introduced chronic migraine, but this diagnosis resembled more a high-frequency migraine rather than the actual migraine transformation process. It also introduced medication overuse headache, but it necessitated analgesic withdrawal and subsequent headache improvement to be diagnosed as such. Hence patients having medication overuse headache could only be diagnosed in retrospect, which was an awkward situation. Such restrictive criteria for chronic migraine and medication overuse headache omitted a high proportion of patients. International Classification of Headache Disorders-3 allows a diagnosis of medication overuse headache due to combination analgesics if taken for at least 10 days per month for more than three months. Hence the prevalence rate of medication overuse headache and chronic migraine can increase compared to the previous version of the headache classification. Different criteria have been used across studies to identify chronic migraine and medication overuse headache, and therefore the information acquired from previous studies using earlier criteria becomes uncertain. Hence much epidemiological research would need to be interpreted cautiously or repeated with the most updated criteria, since the subjects in studies that apply the latest criteria may be phenotypically different from those in older studies.

• Journal of Periodontal and Implant Science
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• v.52 no.2
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• pp.127-140
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• 2022

Purpose: In dental avulsion, delayed replantation usually has an uncertain prognosis. After tooth replantation, complex inflammatory responses promote a return to periodontal tissue homeostasis. Various types of cytokines are produced in the inflammatory microenvironment, and these cytokines determine the periodontal tissue response. This study aimed to identify the gene expression profiles of replanted teeth and evaluate the functional differences between immediate and delayed replantation. Methods: Maxillary molars from Sprague-Dawley rats were extracted, exposed to a dry environment, and then replanted. The animals were divided into 2 groups according to the extra-oral time: immediate replantation (dry for 5 minutes) and delayed replantation (dry for 60 minutes). Either 3 or 7 days after replantation, the animals were sacrificed. Periodontal soft tissues were harvested for mRNA sequencing. Hallmark gene set enrichment analysis was performed to predict the function of gene-gene interactions. The normalized enrichment score (NES) was calculated to determine functional differences. Results: The hallmark gene sets enriched in delayed replantation at 3 days were oxidative phosphorylation (NES=2.82, Q<0.001) and tumor necrosis factor-alpha (TNF-α) signaling via the nuclear factor kappa light chain enhancer of activated B cells (NF-κB) pathway (NES=1.52, Q=0.034). At 7 days after delayed replantation, TNF-α signaling via the NF-κB pathway (NES=-1.82, Q=0.002), angiogenesis (NES=-1.66, Q=0.01), and the transforming growth factor-beta signaling pathway (NES=-1.46, Q=0.051) were negatively highlighted. Conclusions: Differentially expressed gene profiles were significantly different between immediate and delayed replantation. TNF-α signaling via the NF-κB pathway was marked during the healing process. However, the enrichment score of this pathway changed in a time-dependent manner between immediate and delayed replantation.

• Journal of the Korea Society for Simulation
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• v.32 no.3
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• pp.67-74
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• 2023

A semiconductor fabrication facility(FAB) is one of the most capital-intensive and large-scale manufacturing systems which operate under complex and uncertain constraints through hundreds of fabrication steps. To improve fab performance with intuitive scheduling, practitioners have used weighted-sum scheduling. Since the determination of weights in the scheduling significantly affects fab performance, they often rely on simulation-based decision making for obtaining optimal weights. However, a large-scale and high-fidelity simulation generally is time-intensive to evaluate with an exhaustive search. In this study, we investigated three sampling methods (i.e., Optimal latin hypercube sampling(OLHS), Genetic algorithm(GA), and Decision tree based sequential search(DSS)) for the optimization. Our simulation experiments demonstrate that: (1) three methods outperform greedy heuristics in performance metrics; (2) GA and DSS can be promising tools to accelerate the decision-making process.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.77-86
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• 2023

Purpose : This study systematically assessed 9 emotion-function programs for schizophrenic individuals that have been implemented over the past 10 years in Korea and abroad, with the objective of providing clinical grounds and data for further programs. Methods : This study identified 2,558 studies from among those registered in the RISS, KISS, EMbase, PubMed and Scopus databases from 2013 to September 2023, using 'schizophrenia' AND 'emotion' AND ('program' OR 'therapy') as keywords. Of the 2,558 studies retrieved from electronic databases, 602 duplicate papers were excluded. After this process, 1,915 papers that did not meet the study's inclusion and exclusion criteria were excluded based on their titles and abstracts. Following a review of the texts of the remaining 41 papers, nine papers were finally selected, excluding 32 papers according to the selection and exclusion criteria. Results : Programs for the emotional function of patients with schizophrenia have continued to be researched. The results of an evaluation on the quality of the selected literature confirmed that a majority of the reviewed items were "uncertain", confirming that there was a risk of bias. The interventions for emotions included art, cognitive-behavioral, and physical programs, of which art programs were frequently applied. Most of the interventions were implemented in hospitals. The dependent variables for evaluating emotions included emotional expression, depression, anxiety, and positive emotions, and among them, emotional expression was used most frequently. Accordingly, the Berkeley expressivity questionnaire was commonly used as an evaluation tool. Conclusion : This study is significant for intending to analyze domestic and overseas programs for the emotions of patients with schizophrenia, thereby proposing the direction for planning and applying interventions in clinical settings. In follow-up studies, it will be necessary to develop a protocol that confirms interventions according to the settings and patient characteristics of programs and expands the scope of literature reviews.

• Journal of Korea Trade
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• v.26 no.6
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• pp.41-60
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• 2022

Purpose - The policy implications of free trade agreements have traditionally been a matter of debate among economists. The official signing of the Korea-China Free Trade Agreement provides economists with a quasi-natural experiment to analyze the FTA's policy effects. This article aims to more accurately understand the impact of Korea's FTA accession on the macro economy. Design/methodology - This study adopts the counterfactual method based on panel data to find common factors in the generation process of macro data to fit the counterfactual path, to accurately evaluate the effect of the macro policy. Findings - Our research results show that the signing of the Korea-China FTA has a relatively significant short-term positive effect on Korea's economic growth. On average, Korea's real GDP growth rate has increased by 2.1%. This study finds evidence in support of FTA signing not having a significant impact on Korea's GDP growth in the long run. Additionally, we evaluated the impact of the FTA on Korea's imports and exports and found that it had a significant positive impact in the short term, but the trade effect of the FTA is significantly affected by the external macro-environment. Originality/value - First, this study uses macro panel data at the national level to examine the impact of the Korea-China FTA on Korea, and more accurately describes the policy effect of the FTA. Second, our empirical results show that the Korea-China FTA policy impact is subject to occasional changes in the external environment, such as the geopolitical conflict (crisis) between Korea and China, and the US-China trade war. Finally, the analysis shows that the short-term effect of FTA is significant but the long-term is uncertain, which provides empirical evidence for the debate on whether joining FTA can promote national economic growth.

• The Journal of Bigdata
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• v.7 no.1
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• pp.75-87
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• 2022

This study investigates a dynamic flexible flow shop scheduling problem under uncertain rework operations for an automobile pipe production line. We propose a weighted dispatching rule (WDR) based on the multiple dispatching rules to minimize the weighted sum of average flowtime and tardiness. The set of weights in WDR should be carefully determined because it significantly affects the performance measures. We build a discrete-event simulation model and propose a genetic algorithm to optimize the set of weights considering complex and variant operations. The simulation experiments demonstrate that WDR outperforms the baseline dispatching rules in average flowtime and tardiness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.617-626
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• 2006

The purpose of contingency estimate is to manage the increase in construction cost and the extension of the term of works due to the inevitable occurrence of uncertain situations. The aim of contingency strategies have two intentions. One thing, can be called a passive strategy, gets ready for construction cost increase due to uncertainty factors, the other thing, can be called a active strategy, gets rid of the obstruction factors of work prior to construction performance. Therefore, from the view point of medium and long term, there is necessary to accumulate data in conjunction with design modification cases and carefully analyze uncertainty factors from construction types and characters. Therefore, this thesis will analyze design modification case at a special work such as highway and select factors that affect construction cost and present contingency estimate process using regression analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.57-65
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• 2024

In a fire-resistant structure, uncertainties arise in factors such as ventilation, material elasticity modulus, yield strength, coefficient of thermal expansion, external forces, and fire location. The ventilation uncertainty affects thefactor contributes to uncertainties in fire temperature, subsequently impacting the structural temperature. These temperatures, combined with material properties, give rise to uncertain structural responses. Given the nonlinear behavior of structures under fire conditions, calculating fire fragility traditionally involves time-consuming Monte Carlo simulations. To address this, recent studies have explored leveraging machine learning algorithms to predict fire fragility, aiming to enhance efficiency while maintaining accuracy. This study focuses on predicting the fire fragility of a steel moment frame building, accounting for uncertainties in fire size, location, and structural material properties. The fragility curve, derived from nonlinear structural behavior under fire, follows a log-normal distribution. The results demonstrate that the proposed method accurately and efficiently predicts fire fragility, showcasing its effectiveness in streamlining the analysis process.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.19 no.5
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• pp.61-84
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• 2024

The purpose of this study is to deeply analyze the career transition experience and the essence of the entrepreneurial process of women who experienced a career break in middle age, to understand the career transition experience of women who experienced a career break in middle age, and to present a theoretical framework for the entrepreneurial settlement process. The research participants were 17 women who got a job in middle age after a career break or started a business through a career change during their career. Based on this, data were collected through in-depth interviews, and a qualitative analysis was conducted by applying the grounded theory research method proposed by Strauss and Corbin (2008, 2001). The results are as follows. First, 220 concepts, 58 subcategories, and 23 categories were derived. Second, the paradigm of the entrepreneurship process through the career transition experience of middle-aged women with a career gap was derived by setting the exhaustion of work and career identity due to decreased autonomy in uncertain jobs, and the limitations of the immediate jobs and job roles in middle age as the causal situations, and setting the employment barriers after the career gap, re-employment attempts, and job changes in middle age as the contextual situations, setting entrepreneurial efficacy and job maintenance awareness as the mediating conditions of middle-aged entrepreneurial transition, and setting entrepreneurial challenges as actions/interactions in the process of executing career transition behaviors, and setting the process of realizing entrepreneurial vision and business vision through career development. Third, the entrepreneurial decision-making process model through the career transition experience of middle-aged female entrepreneurs with a career gap was implemented in six stages: 'career gap and job maintenance stage', 'mid-aged career limitation recognition stage', 'subjective career and independent life accompanying stage', 'career transition and entrepreneurship execution stage', 'entrepreneurial career capacity building stage', and 'entrepreneurial career growth and change stage'. Fourth, the core category through the story outline was found to be 'career development and career development efforts and entrepreneurship tasks for overcoming adversity through career transition experience'. Through each category of the core category and paradigm model, the career transition experience and entrepreneurship competency performance in the entrepreneurship process of middle-aged female entrepreneurs were classified into three entrepreneurship types: entrepreneurship career development expansion type, entrepreneurship career meaning pursuit type, and entrepreneurship career stability maintenance type. This study presented what middle-aged start-up women with career interruptions actually experience in the entrepreneurship process through career transition experience. The significance of this study lies in revealing the entrepreneurship path of middle-aged women who recognize entrepreneurial efficacy by utilizing their strengths and competencies through career transition and work life after career interruption and pursue career development through the process of entrepreneurial challenge and settlement. Based on these results, the career transition experience and entrepreneurship path of middle-aged women who start a business after career interruption were discussed, and suggestions for the significance of this study and follow-up research were made.

• Korean Journal of Construction Engineering and Management
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• v.9 no.1
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• pp.187-198
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• 2008

There are usually plenty of material inventories in a construction site. More inventories can meet unexpected demands, and also they may have an economical advantage by avoiding a probable escalation of raw material costs. On the other hand, these inventories also cause negative aspects to increase costs for storing redundant inventory as well as decreasing construction productivity. Therefore, a proper method of deciding an optimal level of material inventories while considering dynamic variations of resources under uncertainty is very crucial for the economical efficiency of construction projects. This research presents a stochastic modelling method for construction operations, particularly targeting a work process involving on-site fabrication of raw materials like iron-rebar process (delivery, cut and assembly, and placement). To develop the model, we apply the concept of factory physics to depict the overall components of a system. Then, an optimal inventory management model is devised to support purchase decisions where users can make timely actions on how much to order and when to buy raw materials. Also, optimal time lag, which minimizes the storage time for pre-assembled materials, is obtained. To verify this method, a real case is applied to elicit an optimal amount of inventory and time lag. It is found that average values as well as variability of inventory level decreased significantly so as to minimize economic costs related to inventory management under uncertain project condition.