• Nutrition Research and Practice
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• v.13 no.6
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• pp.498-508
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• 2019

BACKGROUND/OBJECTIVES: Lower circulating 25-hydroxyvitamin D [25(OH)D] levels are associated with a higher risk of hypertension (HTN); however, it remains unclear whether the relationship is causal. We aimed to evaluate the causal effects of circulating 25(OH)D levels on the prevalence of HTN in the Korean population using the Mendelian randomization (MR) approach. SUBJECTS/METHODS: Epidemiological data, serum 25(OH)D data, and genomic DNA biospecimens were obtained from 2,591 participants, a subset of the study population in the Korea National Health and Nutrition Survey 2011-2012. Five 25(OH)D-related single nucleotide polymorphisms (SNPs; DHCR7 rs12785878, CYP2R1 rs10741657, CYP2R1 rs12794714, CYP24A1 rs6013897, and GC rs2282679), identified a priori from genome-wide association studies, were used as instrument variables (IVs) for serum 25(OH)D levels. In the MR analysis, we performed IV analyses using the two-stage least squares method. RESULTS: In the observational analysis, circulating 25(OH)D levels were found to be inversely associated with the HTN prevalence in ordinary least squares models (odds ratio: 0.97, 95% confidence interval: 0.96, 0.99) after adjusting for the potential confounders. There were differences in the circulating 25(OH)D levels across genotypes of individual SNPs. In the MR analysis, using individual SNPs as IVs, 25(OH)D levels were not associated with the HTN prevalence. CONCLUSIONS: We found no association between genetically determined circulating 25(OH)D levels and HTN in Korean adults. Our results are listed owing to the relatively small sample size and possible weak instrument bias; therefore, further studies are needed to confirm these results.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.46-53
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• 1999

As of July 1999, i,185 lomocotives(excluding metropolitan area electric locomotives) are in Korean National Railroad(KNR). With this limited number of resources assigning locomotives to each trains of timetable is very important in the entire railway management point of view because schedule can be regarded as goods in transportation industry. On a simple rail network, it is rather easier to assign proper locomotives to trains with the experience of operating experts and get optimal assignment solution. However, as the network is getting bigger and complicated, the number of trains and corresponding locomotives will be dramatically increased to rover all the demands required to service all of the trains in timetable. There will be also numerous operational constraints to be considered. Assigning proper locomotives to trains and building optimal cyclic rotations of locomotive routings will result in increasing efficiency of schedule and giving a guarantee of more profit. The purpose of this study is two fold: (1) we consider a planning-level locomotive scheduling problem with the objective of minimizing the wasting cost under various practical constraints and (2) development of implementation prototype program of its assigning result. Not like other countries, i.e. Canada, Sweden, Korean railroad operates on n daily schedule basis. The objective is to find optimal assignment of locomotives of different types to each trains, which minimize the wasting cost. This problem is defined on a planning stage and therefore, does not consider operational constraints such as maintenance and emergency cases. Due to the large scale of the problem size and complexity, we approach with heuristic methods and column generation to find optimal solution. The locomotive scheduling prototype consists of several modules including database, optimization engine and diagram generator. The optimization engine solves MIP model and provides an optimal locomotive schedule using specified optimization algorithms. A cyclic locomotive route diagram can be generated using this optimal schedule through the diagram generator.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.651-669
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• 2018

This study suggests the prediction model to estimate the specific energy of a pick cutter using a gene expression programming (GEP) and particle swarm optimization (PSO). Estimating the performance of mechanical excavators is of crucial importance in early design stage of tunnelling projects, and the specific energy (SE) based approach serves as a standard performance prediction procedure that is applicable to all excavation machines. The purpose of this research, is to investigate the relationship between UCS and BTS, penetration depth, cut spacing, and SE. A total of 46 full-scale linear cutting test results using pick cutters and different values of depth of cut and cut spacing on various rock types was collected from the previous study for the analysis. The Mean Squared Error (MSE) associated with the conventional Multiple Linear Regression (MLR) method is more than two times larger than the MSE generated by GEP-PSO algorithm. The $R^2$ value associated with the GEP-PSO algorithm, is about 0.13 higher than the $R^2$ associated with MLR.

• Asia-Pacific Journal of Business
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• v.12 no.1
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• pp.41-56
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• 2021

Purpose - This empirical study examined the influence of post-communist countries sociol-political factor of freedom of expression preconditioning, and trust in agency, mediating performance expectancy of social media users representing the citizens' behavioural intention to utilize social media in a post-communist country, the case of Mongolia. Design/methodology/approach - This research collected 403 valid survey data from citizens those who use social media in Mongolia. The study used Partial Least Squire (PLS) analysis with the research conceptual model founded on the UTAUT model. Findings - The study shown that citizens in post-communist, they strongly willing freedom of expression, which driving as a positive precondition factor, and this has an indirect positive influence, and trust in agency mediates to enhance performance expectancy. Social influence, and effort expectancy factors have direct positive influence on the intention to use of social media systems in the public sector domain of Mongolia. Research implications or Originality - This research proposed a new model to test citizens' intention to use social media as a communication tool to engage with public organizations in the pre-adoption stage of post-communist countries. Theoretically, this research builds up to the unique theoretical contribution with social media by examining a new social media-based third-party intercommunication medium, incorporating intent to utilize for citizens with government in post-communist countries. Practically, this article lays out the directions to aid social media usage for government sector with concerning citizens intentions in the post-communist situation.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.12
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• pp.135-144
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• 2018

This paper deals with preservation and restoration as a universal approach to conserve architectural heritage. The questions on how to preserve or restore them have been always major issues for many old buildings. Reading changes in ways of the thinking to solve such matters in the past helps to grasp the fundamental concepts to conserve cultural heritage at this point in time. The method is an important stage that leads to change our current attitude. Both the ways of the thinking for preservation and restoration should be re-interpreted to preserve memory or to restore identity depending on the current situation, and even should no longer be understood as two opposite options. Therefore, this paper focuses on the epistemological notion and reveals the origin and premise of modern historical perception that has become disconnected from the past works. By taking the writings of $Eug{\grave{e}}ne$-Emmanuel Viollet le Duc, John Ruskin, and Camillo Boito into consideration, the thesis shows that their thought, in the common denominator of the time, is a kind of reflection of consciousness according to particular historical contexts and that their ideas echo three dialectical paradigms derived from past and present, memory and forgetfulness, and history and truth.

• Journal of Gastric Cancer
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• v.20 no.4
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• pp.376-384
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• 2020

Purpose: The role of prophylactic abdominal drainage in total gastrectomy is not well-established. This study aimed to evaluate the efficacy of abdominal drainage in the prevention and management of major intra-abdominal complications after total gastrectomy for gastric carcinoma. Materials and Methods: We retrospectively reviewed the data of 499 patients who underwent total gastrectomy for gastric carcinoma in a high-volume institution. The patients were divided into drainage and non-drainage groups and compared for the development and management of major intra-abdominal complications, including anastomotic leak, abdominal bleeding, abdominal infection, and pancreatic fistulas. Results: The drainage group included 388 patients and the non-drainage group included 111 patients. The 2 groups showed no significant differences in clinicopathological characteristics or operative procedures, except for more frequent D2 lymphadenectomies in the drainage group. After surgery, the overall morbidity (drainage group vs. non-drainage group: 24.7% vs. 28.8%, P=0.385) and incidence of major intra-abdominal complications (6.4% vs. 6.3%, P=0.959) did not significantly differ between the two groups. The non-drainage group showed no significant increase in the incidence rate of major intra-abdominal complications in the subgroups divided by age, sex, comorbidity, operative approach, body mass index, extent of lymphadenectomy, and pathological stage. Abdominal drainage had no significant impact on early diagnosis, secondary intervention or reoperation, or recovery from major intra-abdominal complications. Conclusions: Prophylactic abdominal drainage showed little demonstrable benefit in the prevention and management of major intra-abdominal complications of total gastrectomy for gastric carcinoma.

• BMB Reports
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• v.55 no.5
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• pp.205-212
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• 2022

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disorder characterized by suprapubic pain and urinary symptoms such as urgency, nocturia, and frequency. The prevalence of IC/BPS is increasing as diagnostic criteria become more comprehensive. Conventional pharmacotherapy against IC/BPS has shown suboptimal effects, and consequently, patients with end-stage IC/BPS are subjected to surgery. The novel treatment strategies should have two main functions, anti-inflammatory action and the regeneration of glycosaminoglycan and urothelium layers. Stem cell therapy has been shown to have dual functions. Mesenchymal stem cells (MSCs) are a promising therapeutic option for IC/BPS, but they come with several shortcomings, such as immune activation and tumorigenicity. MSC-derived extracellular vesicles (MSC-EVs) hold numerous therapeutic cargos and are thus a viable cell-free therapeutic option. In this review, we provide a brief overview of IC/BPS pathophysiology and limitations of the MSC-based therapies. Then we provide a detailed explanation and discussion of therapeutic applications of EVs in IC/BPS as well as the possible mechanisms. We believe our review will give an insight into the strengths and drawbacks of EV-mediated IC/BPS therapy and will provide a basis for further development.

• Asia-Pacific Journal of Business
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• v.13 no.1
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• pp.37-52
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• 2022

Purpose - The objective of this study is to investigate what motivates global FDI inflows in the different economic development level and to clarify the FDI motivation type in the level of qualitative economic growth. Design/methodology/approach - Major macroscopic social·economic factors induced FDI inflows were analyzed using fixed-effect panel regression with 30-year panel data of 28 countries from 1985 to 2014. For analysis in the stage of economic growth, two category of developed and developing countries was used. And to analyze FDI motivation type in the level of qualitative economic growth, 4 shares of GDP; consumption·government·investment expenditure and export, was used as explanatory variable. Findings - In developed country, TFP(total factor productivity) and GDP have a great influence on FDI inflows, and consumption and labor compensation have a slight effect. This result indicates that the market seeking-driven, horizontal type investment is shown along with efficiency seeking investment. In developing country, human capital and TFP is shown to have greater impact on FDI inflows and labor compensation, exports, investment and government expenditures also have impacts. Thus it has confirmed that not only efficiency-seeking vertical investment for using low cost well educated laborer, but also government-driven economic growth and export policies could affect the FDI inflows. Research implications or Originality - The FDI investment decision making of multinational companies is decided by their own purpose. But, in the concept of as follows; 1) FDI is a long-term capital flowing for maximization of economic utility with limited global resource, 2) Thus FDI could be affected by macro socio·economic factors of host country. 3) Also such macro factors is different by each economic growth qualitative level. Therefore macro socio·economic factors of each country could be affected by the qualitative level of their own economic growth. To attract FDI inflows, it is desirable to implement differentiated incentive policies in the qualitative level of economic growth. Furthermore in developing countries it is recommended to implement government driven economic growth policies as follows; fostering well educated human resources, improving technology productivity in the relative lower cost labor market compared to developed countries and boosting international export volume.

• Asia-Pacific Journal of Business
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• v.12 no.4
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• pp.289-297
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• 2021

Purpose - This study analyzed the correlation between economic liberalization and foreign direct investment. The purpose of this study is to seek ways to attract foreign direct investment from developing countries. Design/methodology/approach - This study analysed with observations of 19 from 2000 to 2018 using a fixed effect model, a random effect model, and a two-way fixed effect model. Findings - First, it was found that economic liberalization had a positive effect on attracting foreign direct investment in the early stages of economic liberalization. Second, it was found that economic liberalization in the deepening stage of economic liberalization had a negative effect on attracting foreign direct investment. In general, it was found that the higher the level of economic liberalization in developing countries is not accompanied by innovative changes in the industrial structure, the higher the level of economic liberalization is likely to decrease the inducement of foreign direct investment due to negative factors such as an increase in labor costs. Overall, this study approved that Economic liberalization have a non-linear (inverted U-shape) relationship with the inflow of foreign direct investment. Research implications or Originality - First, this study attempted to expand the variables for the determinants of FDI by analyzing economic factors which is a determinent of FDI. Second, economic liberalization generally has a positive effect on foreign direct investment, but it proved that it does not have only positive effects as a factor of attracting foreign direct investment in developing countries. The advantage of low wages in ASEAN countries acts as a factor for foreign direct investment, but as the degree of economic liberalization increases, the environment such as government size, guarantee of property rights, international trade freedom, fiscal soundness, and regulations change positively. On the other hand, it can be suggested that if the industrial level is less, it may lead to a loss of comparative advantage and a decrease in investment.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1825-1834
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• 2022

Performing high-fidelity computational fluid dynamics (HF-CFD) to predict the flow and heat transfer state of the coolant in the reactor core is expensive, especially in scenarios that require extensive parameter search, such as uncertainty analysis and design optimization. This work investigated the performance of utilizing a multi-fidelity reduced-order model (MF-ROM) in PWR rod bundles simulation. Firstly, basis vectors and basis vector coefficients of high-fidelity and low-fidelity CFD results are extracted separately by the proper orthogonal decomposition (POD) approach. Secondly, a surrogate model is trained to map the relationship between the extracted coefficients from different fidelity results. In the prediction stage, the coefficients of the low-fidelity data under the new operating conditions are extracted by using the obtained POD basis vectors. Then, the trained surrogate model uses the low-fidelity coefficients to regress the high-fidelity coefficients. The predicted high-fidelity data is reconstructed from the product of extracted basis vectors and the regression coefficients. The effectiveness of the MF-ROM is evaluated on a flow and heat transfer problem in PWR fuel rod bundles. Two data-driven algorithms, the Kriging and artificial neural network (ANN), are trained as surrogate models for the MF-ROM to reconstruct the complex flow and heat transfer field downstream of the mixing vanes. The results show good agreements between the data reconstructed with the trained MF-ROM and the high-fidelity CFD simulation result, while the former only requires to taken the computational burden of low-fidelity simulation. The results also show that the performance of the ANN model is slightly better than the Kriging model when using a high number of POD basis vectors for regression. Moreover, the result presented in this paper demonstrates the suitability of the proposed MF-ROM for high-fidelity fixed value initialization to accelerate complex simulation.