• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.77-85
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• 2009

This paper describes the findings obtained from a research project aimed at investigating, via 1 g laboratory model tests, the ground movements caused by multiple side-by-side (sbs) tunnel construction in clay. The ground movements above a second tunnel showed different trends from those observed above a first tunnel. These trends include an increase in the overall volume loss, and a widening of the settlement troughs on the near limb of the trough accompanied by a shift of the maximum settlement towards existing tunnel. This would suggest that the use of simple predictive methods of adopting a Gaussian curve for analysing the ground settlements associated with twin (sbs) tunnel construction is not appropriate. Therefore the current paper adopts a method that modifies the Gaussian curve approach in order to improve the predictions. This paper comments on the parameter selection involved with adopting this new method to apply it to full-scale field situations, and also discusses its limitations.

• Korea Trade Review
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• v.41 no.5
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• pp.89-111
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• 2016

The Mega-FTA is intended for emerging economies, including developed economies, to expand economies of scale in a single market. The Bilateral FTA shall take into account the relevant industries and the inter-country related industries to adjust the origin standard and preferential tariff rates. Therefore, certain competitive industries can expect foreign investment and re-investment in the domestic market as well as expansion of the market in the region. However, the mega-FTA should expand the size of the economy under the same preferential tax rates for many Partner countries. The Mega-FTA can maximize the effectiveness of the agreement by making use of the competitive advantages of the participating countries. In the mega-FTA, Cumulative Criteria should be appropriately used as a supplemental standard of origin. The Cumulative Criteria is an important FTA utilization factor that determines the success of the mega-FTA. Using FTA, Korea should export locally produced materials using cheaper labor force in FTA partner country. In addition, in order to prepare the Mega-FTA, which allows full cumulation, it is necessary to encourage the overseas transfer of low-cost structure materials processing industry so that the material suppliers can be transferred to the area where production cost is lower and raw material supply is easier.

• Nutrition Research and Practice
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• v.17 no.4
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• pp.803-811
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• 2023

BACKGROUND/OBJECTIVES: Nutrition knowledge has been reported to have a weak positive effect on healthy eating behavior. This study aimed to determine if there was a difference in nutrition knowledge depending on the choice of science subject in high school and whether that affected the actual eating habits of college students in Japan. SUBJECTS/METHODS: The subjects were 514 college students, the majority first-year students, in 3 cities in Japan. A questionnaire survey was conducted on elective subjects in science in high school, diet (11 items), lifestyle (5 items), and nutrition knowledge (34 questions). The preliminary survey was conducted on 47 students in the fall of 2019, and the full-scale survey was conducted in May-June and October-November 2021 at the end of lectures for the first-year students. RESULTS: The students in the high-score group (24-31 points, n = 180) had a higher intake of vegetables (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.12-2.82; P = 0.015) and breakfast (OR, 1.64; 95% CI, 1.03-2.60; P = 0.035), and a reduced intake of fast food (OR, 0.27; 95% CI, 0.14-0.51; P < 0.001) than those in the low-score group (6-19 points, n = 150). Only the biology and chemistry students had significantly higher nutrition scores than the other groups (all: P < 0.001), but no significant difference was found between the other groups. Understanding nutrition learned in elementary and junior high school is appropriate, while molecular structure, recommended amount, and food poisoning were insufficient. CONCLUSIONS: Knowledge of nutrition appears to have a positive effect on the actual eating habits of college students. Although biology and chemistry in high school may help students understand the foundations of good nutrition, specialized food education may be required to make informed dietary choices.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.311-318
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• 2006

This paper presents experimental studies on investigating the seismic retrofit performance of reinforced concrete circular columns with poor lap-splice details using GFRP wrapping. Five full-scale model columns have been tested. The prototype structure is an existing circular reinforced concrete bridge piers designed following the pre-seismic codes and constructed in South Korea in 1979. The as-built column will be expected to suffer brittle failure due to the bond failure of lap-spliced longitudinal reinforcement. The retrofitted columns using GFRP wrapping showed significant improvement of seismic performance. However, the predicted flexural failure mode was not achieved and the longitudinal bars were not yielded. Failure modes of the retrofitted columns are considered to be the gradually delayed bond slip in lap-spliced longitudinal reinforcement. Suggested retrofit design methods using GFRP were validated experimentally.

• Land and Housing Review
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• v.15 no.1
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• pp.99-115
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• 2024

This study aims to investigate Marseille's Euromméditerranée project and provide policy implications for revitalizing domestic urban regeneration projects. First, we identify Euroméditerranée as a pivotal urban regeneration effort, executed by EPAEM-an organization fostering governance-driven project advancement through collaboration and investment from both central and local governments. This endeavor has significantly contributed to revitalizing Marseille, enriching the quality of life for its residents. Second, this urban regeneration project has the following notable features: consolidated approach with combination of full redevelopment and rehabilitation, integrated regeneration covering hardware-like physical regeneration and software-like economic, cultural, and environmental regeneration; government-type urban regeneration project structure. Finally, we suggest that policymakers should consider the economic scale in urban regeneration projects, national-level government organizations, and efficient public-private partnerships.

• Smart Structures and Systems
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• v.33 no.2
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• pp.119-131
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• 2024

Drift angle is a significant index for diagnosing post-event structures. A common way to estimate this drift response is by using modal parameters identified under natural excitations. Although the modal parameters of shear structures cannot be identified accurately in the real environment, the identification error has little impact on the estimation when measurements from several floors are used. However, the estimation accuracy falls dramatically when there is only one accelerometer. This paper describes the susceptibility of single sensor identification to modelling error and simulations that preliminarily verified this characteristic. To make a robust evaluation from measurements of one floor of shear structures based on imprecisely identified parameters, a novel scheme is devised to approximately correct the mode shapes with respect to fictitious frequencies generated with a genetic algorithm; in particular, the scheme uses constrained minimization to take both the mathematical aspect and the realistic aspect of the mode shapes into account. The algorithm was validated by using a full-scale shear building. The differences between single-sensor and multiple-sensor estimations were analyzed. It was found that, as the number of accelerometers decreases, the error rises due to insufficient data and becomes very high when there is only one sensor. Moreover, when measurements for only one floor are available, the proposed method yields more precise and appropriate mode shapes, leading to a better estimation on the drift angle of the lower floors compared with a method designed for multiple sensors. As well, it is shown that the reduction in space complexity is offset by increasing the computation complexity.

• Monthly Notices of the Royal Astronomical Society
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• v.501 no.4
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• pp.5616-5645
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• 2021

We analyse the large-scale clustering in Fourier space of emission line galaxies (ELG) from the Data Release 16 of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey. The ELG sample contains 173 736 galaxies covering 1170 deg² in the redshift range 0.6 eff = 0.845 we measure D_V(z_eff)/r_drag = 18.33^+0.57_-0.62, with D_V the volume-averaged distance and r_drag the comoving sound horizon at the drag epoch. In combination with the RSD measurement, at z_eff = 0.85 we find fσ₈(z_eff) = 0.289^+0.085_-0.096, with f the growth rate of structure and σ₈ the normalization of the linear power spectrum, D_H(z_eff)/r_drag = 20.0^+2.4_-2.2 and D_M(z_eff)/r_drag = 19.17 ± 0.99 with D_H and D_M the Hubble and comoving angular distances, respectively. These results are in agreement with those obtained in configuration space, thus allowing a consensus measurement of fσ₈(z_eff) = 0.315 ± 0.095, D_H(z_eff)/r_drag = 19.6^+2.2_-2.1 and D_M(z_eff)/r_drag = 19.5 ± 1.0. This measurement is consistent with a flat ΛCDM model with Planck parameters.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.41-48
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• 2004

We may consider the inducement of demand to public transportation as a solution to relieve traffic congestion and pollution. Subway has merits as moving on schedule, transporting more people than bus. But subway is required a vast investment in the early stage of construction has a huge debt. So it runs into red figures, and on this account, services of subway are falling more and more. Development of subway's operation cost function is useful to understand structure of subway's operation and catch the relations of operation cost and actual results. In addition, we can present the policy that is a helpful to the operation as development of operation cost function. But there are short of studies about operation cost deal with a subway comparison with local train. Because local train has many lines and data, on the other hand, subway has one to four lines and less data. Most of previous studies sought the operation cost function of Seoul. So this study aimed to develop and apply the operation cost function of Seoul, Incheon, Busan and Daegu area using full allocation method. In this study, we considered the number of passengers, track-km, train-km, revenue as actual results. By appling the operation cost function, we compared the average cost of each city and confirmed the existence of economies of scale about the number of passengers, train-km.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.78-86
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• 2019

This paper describes the stiffness optimization of the torsion spring hinge of the large SAR antenna considering the deployment performance. A large SAR antenna is folded in a launch environment and then unfolded when performing a mission in orbit. Under these conditions, it is very important to find the proper stiffness of the torsion spring hinge so that the antenna panels can be deployed with minimal impact in a given time. If the torsion spring stiffness is high, a large impact load at the time of full deployment damages the structure. If it is weak, it cannot guarantee full deployment due to the deployment resistance. A multi-body dynamics analysis model was developed to solve this problem using RecurDyn and the development performance were predicted in terms of: development time, latching force, and torque margin through deployment analysis. In order to find the optimum torsion spring stiffness, the deployment performance was approximated by the response surface method (RSM) and the optimal design was performed to derive the appropriate stiffness value of the rotating springs.

• Tunnel and Underground Space
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• v.30 no.6
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• pp.509-518
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• 2020

This study constructed a new simulation platform, including mesh generation process, numerical simulation, and post-processing for results analysis based on exploration data to perform real-scale numerical analysis considering the actual geological structure efficiently. To build the simulation platform, we applied for open-source programs. The source code is open to be available for code modification according to the researcher's needs and compatibility with various numerical simulation programs. First, a three-dimensional model(3D) is acquired based on the exploration data obtained using a drone. Then, the domain's mesh density was adjusted to an interpretable level using Blender, the free and open-source 3D creation suite. The next step is to create a 3D numerical model by creating a tetrahedral volume mesh inside the domain using Gmsh, a finite element mesh generation program. To use the mesh information obtained through Gmsh in a numerical simulation program, a converting process to conform to the program's mesh creation protocol is required. We applied a Python code for the procedure. After we completed the stability analysis, we have created various visualization of the study using ParaView, another open-source visualization and data analysis program. We successfully performed a preliminary stability analysis on the full-scale Dokdo model based on drone-acquired data to confirm the usefulness of the proposed platform. The proposed simulation platform in this study can be of various analysis processes in future research.