• Experimental and Molecular Medicine
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• v.50 no.12
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• pp.2.1-2.12
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• 2018

Glucagon-like peptide-1 (GLP-1) has a broad spectrum of biological activity by regulating metabolic processes via both the direct activation of the class B family of G protein-coupled receptors and indirect nonreceptor-mediated pathways. GLP-1 receptor (GLP-1R) agonists have significant therapeutic effects on non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) in animal models. However, clinical studies indicated that GLP-1 treatment had little effect on hepatic steatosis in some NAFLD patients, suggesting that GLP-1 resistance may occur in these patients. It is well-known that the gut metabolite sodium butyrate (NaB) could promote GLP-1 secretion from intestinal L cells. However, it is unclear whether NaB improves hepatic GLP-1 responsiveness in NAFLD. In the current study, we showed that the serum GLP-1 levels of NAFLD patients were similar to those of normal controls, but hepatic GLP-1R expression was significantly downregulated in NAFLD patients. Similarly, in the NAFLD mouse model, mice fed with a high-fat diet showed reduced hepatic GLP-1R expression, which was reversed by NaB treatment and accompanied by markedly alleviated liver steatosis. In addition, NaB treatment also upregulated the hepatic p-AMPK/p-ACC and insulin receptor/insulin receptor substrate-1 expression levels. Furthermore, NaB-enhanced GLP-1R expression in HepG2 cells by inhibiting histone deacetylase-2 independent of GPR43/GPR109a. These results indicate that NaB is able to prevent the progression of NAFL to NASH via promoting hepatic GLP-1R expression. NaB is a GLP-1 sensitizer and represents a potential therapeutic adjuvant to prevent NAFL progression to NASH.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.100-106
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• 2019

Ground and high altitude simulated combustion experiments were conducted using a liquid rocket engine with hydrogen peroxide and kerosene as the propellant. A ground and high altitude simulated combustion test facility was constructed by installing a high altitude model diffuser and TMS (Thrust Measuring System) on a vertical combustion test bench. The thrust characteristics according to altitude were investigated using the combustion test equipment. The diffuser was designed on a 1:4.8 scale to verify the characteristics of the high diffusing diffuser and starting pressure. The cold flow tests were conducted using nitrogen gas, and the performance characteristics and starting characteristics of the scale down diffuser were verified. A diffuser and TMS were installed on the vertical combustion test bench, and the thrust correction equations for the system resistance were derived. The thrust correction equations were derived from the step test and vacuum step test before the actual hot firing test. Nozzles with an operating altitude of 10km were designed. Hot firing tests were conducted to analyze the thrust characteristics according to the operating altitude changes. The actual thrust was calculated using each correction equation with the thrust value measured by the TMS.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.333-340
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• 2019

Tests using a middle velocity propulsion impact machine (MVPIM) were performed to verify the impact resistance capability of sandwich concrete panels (SCP) in a modular liquefied natural gas (LNG) outer tank, and numerical models were constructed and analyzed. $2{\times}2m$ specimens with plain sectional characteristics and specimens including a joint section were used. A 51 kg missile was accelerated above 45 m/s and impacted to have the design code kinetic energy. Impact tests were performed twice according to the design code and once for the doubled impact speed. The numerical models for simulating impact behaviors were created by LS-DYNA. The external steel plate and filled concrete of the panel were modeled as solid elements, the studs as beam elements, and the steel plates as elasto-plastic material with fractures; the CSCM material model was used for concrete. The front plate deformations demonstrated good agreement with those of other tests. However the rear plate deformations were less. In the doubled speed test for the plain section specimen, the missile punctured both plates; however, the front plate was only fractured in the numerical analysis. The impact energy of the missile was transferred to the filled concrete in the numerical analysis.

• Development and Reproduction
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• v.23 no.3
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• pp.223-229
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• 2019

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance (IR). T2DM is correlated with obesity and most T2DM medications have been developed for enhancing insulin sensitivity. Silk protein fibroin (SPF) from spiders has been suggested as an attractive biomaterial for medical purposes. We generated transgenic rice (TR) expressing SPF and fed it to diabetic $BKS.Cg-m+/+Lepr^{db}$ mice to monitor the changes in blood glucose levels and adipose tissue proteins associated with energy metabolism and insulin signaling. In the present study, the adipocyte size in abdominal fat in TR-SPF-fed mice was remarkably smaller than that of the control. Whereas the adenosine monophosphate-activated protein kinase (AMPK)-activated protein kinase and insulin receptor substrate 1 (IRS1) protein levels were increased in abdominal adipose tissues after TR-SPF feeding, levels of six-transmembrane protein of prostate 2 (STAMP2) proteins decreased. Phosphorylation of AMPK at threonine 172 and IRS1 at serine 307 and tyrosine 632 were both increased in adipose tissues from TR-SPF-fed mice. Increased expression and phosphorylation of IRS1 at both serine 307 and tyrosine 632 in adipose tissues indicated that adipocytes obtained from abdominal fat in TR-SPF-fed mice were more susceptible to insulin signaling than that of the control. STAMP2 protein levels decreased in adipose tissues from TR-SPF-fed mice, indicating that STAMP2 proteins were reducing adipocytes that were undergoing lipolysis. Taken together, this study showed that TR-SPF was effective in reducing blood glucose levels in diabetic mice and that concurrent lipolysis in abdominal adipocytes was associated with alterations of AMPK, IRS1, and STAMP2. Increased IRS1 expression and its phosphorylation by TR-SFP were considered to be particularly important in the induction of lipolysis in adipocytes, as well as in reducing blood glucose levels in this animal model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.533-541
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• 2021

Retaining walls have been used to prevent slope failure through resistance of earth pressure in railway, road, nuclear power plant, dam, and river infrastructure. To calculate dynamic earth pressure and determine the characteristics for seismic behavior, many researchers have analyzed the nonlinear response of ground and structure based on various numerical analyses (FLAC, PLAXIS, ABAQUS etc). In addition, seismic fragility evaluation is performed to ensure safety against earthquakes for structures. In this study, we used the FLAC2D program to understand the seismic response of the inverted T-type wall with a backfill slope, and evaluated seismic fragility based on relative horizontal displacements of the wall. Nonlinear site response analysis was performed for each site (S2 and S4) using the seven ground motions to calculate various seismic loadings reflecting site characteristics. The numerical model was validated based on other numerical models, experiment results, and generalized formula for dynamic active earth pressure. We also determined the damage state and damage index based on the height of retaining wall, and developed the seismic fragility curves. The damage probabilities of the retaining wall for the S4 site were computed to be larger than those for the S2 site.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.209-217
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• 2021

This paper investigates the effect of high strength hooked-end steel fiber content and aspect ratio on the compressive and flexural performance of concrete. A total of ten mixtures were prepared and tested. Concretes with specific compressive strength of 30 MPa were reinforced with three different aspect ratios (l/d) of steel fibers 64, 67, and 80 and three different percentages of steel fibers 0.25, 0.50, and 0.75% by volume of concrete. Tensile strengths of steel fibers with l/d of 64, 67, and 80 are 2,000, 2,400, and 2,100 MPa, respectively. The compressive and flexural properties of plain and steel fiber-reinforced concrete (SFRC) mixtures were evaluated and compared. The experimental results indicated that the incorporation of high-strength hooked-end steel fibers had significant effects on the compressive and flexural performance of concrete. With the increase of steel fiber content, compressive performances, such as Poisson's ratio and toughness, of concrete were improved. The steel fibers with the least l/d of 67 resulted in a larger enhancement of compressive performances. The residual flexural strength, that is, post-cracking flexural resistance and toughness, of concrete is mainly depended on the dosage and aspect ratio of steel fibers. The residual flexural strength at serviceability (SLS) and ultimate limit state (ULS) defined in fib Model Code 2010 (MC2010) is increased as the fiber content and aspect ratio increase.

• Journal of Korean Theatre Studies Association
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• no.48
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• pp.421-446
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• 2012

The purpose of this paper is to shed light onto the historical significance and limitations of the Tsukiji Little Theater's modern performances. The Tsukiji Little Theater holds a position of great importance to the history of both Japanese and Korean modern theater. Some, however, are under the completely opposite impression. There are also mixed opinions about whether the Tsukiji Little Theater is a "model example" of the modern theatrical movement or a "bad example". Based on this controversy, we look into the definitive characteristics of the Tsukiji Little Theater based mostly on "the controversy over translated foreign plays", "the controversy of foreign plays versus original plays", "the value of kabuki" and "Shinpa as a rival". This paper looked into the differences in controversy over translated foreign plays in the Tsukiji Little Theater and the controversy in existing translated foreign plays. It mostly looks at the "casuistry of foreign plays" and the "cultural engineering theory of foreign plays"to get a grasp on the controversy surrounding existing translated foreign plays. Meanwhile, the "internally critical meaning" towards the original plays of renowned writers was strong in the controversy of foreign plays in the Tsukiji Little Theater. Kaoru Osanai defined the 1920s as a dark period, and persisted that because of the activity of the Shingeki movement, foreign plays were needed instead of low-level original plays. This study examines the characteristics of original plays and foreign plays publicly performed at the Tsukiji Little Theater to analyze the "controversy of translated foreign plays versus original plays". The Tsukiji Little Theater mostly put on shows with a strong sense of resistance or that defied the old times. This caused there to be a lot of emphasis put on the rebellious mindset towards old conventions and ideologies for most of the plays, both foreign and original, and the problem arises that little mind was paid to the integrity or beauty of the works. In looking at the "value of kabuki", this paper looked into Kaoru Osanai, who was deeply involved in kabuki actors. He evaluated traditional Japanese arts highly not because of the literary value of their scripts, but because he recognized the value of how they were performed. In order to create a new spectacle, music, dance and mime was taken in from countries around the world, and kabuki was regarded highly as a means of expression on stage. Finally, we also examine the recognized reasons for treating Shinpa as a rival. There is a relationship between these reasons and a complex about the audiences they drew. The Shinpa performances always had many spectators and were successful, but those at the Tsukiji Little Theater were so unpopular with the public that it was hard for them to financially run their theater group. The empty seats in their theater constantly made the modern intellectuals in the Shingeki movement feel inferior.

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.31-38
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• 2019

Recently, there has been an increasing number of ground subsidence (sink-hole) in the downtown areas, and in such a case, it is important to minimize accidents and passages through prompt recovery. With respect to the present recovery method for ground subsidence, the methods of applying the back filling after excavating the ground subsidence or using the grouting injected materials to restore the ground are mostly used, but there has been few studies on materials used for recovering the ground subsidence. Therefore, in order to clarify the characteristics of back filling materials used in the ground subsidence, this study uses the environment-friendly hardening agent to improve the dredged clay, and then, the mixture ratio of hardening agent and mixture ratio of decomposed granite soil is changed to cure for 3, 7, 14 and 28 days to analyze the intensity characteristics of the unconfined compression, and it was compared with the unconfined compression intensity for the previously used cement, a hardening agent. In order to evaluate the characteristics of intensity on the back filling materials, the C.B.R test was carried out, and for the review on whether the back filling materials influence on corrosion of water and sewer pipes and others, the soil non-resistance test was carried out. As a result of the test, for the case of the recovery work of the ground subsidence that requires urgency, it is considered as prudent if the hardening agents of 12% are integrated to cure for 3 days or longer, and for not having the influence on the corrosion of the gas tube or water pipes, it is proposed to mix for 30% or more of the decomposed granite soil. Door model test were conducted To confirm the bearing capacity characteristics of the solidified layer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.8-14
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• 2019

Bird-strike is one of the most important design factors for safety in the aviation industry. Bird-strikes have been the cause of significant damage to aircraft and rotorcraft structures and the loss of life. This study used DYTRAN software to simulate the transient response of an Euler-Lagrangian composite helicopter blade that has been impacted by a bird. The Arbitrary Lagrangian Eulerian (ALE) method and a suitable equation of state were applied to model the bird. ALE was applied to the bird-strike analysis due to the large difference between the properties of the blade and bird. The debris of the bird was assumed to be a fluid and applied as Euler elements after the collision. Through the analysis of bird impacts, the leading-edge of the rotor blade (50.8 mm) was used to identify a positive margin of 1.18 based on the TSAI-FILL criteria. The results are assessed to be sufficiently reliable and may be evaluated to replace tests with various analysis conditions. The structural stability of the rotor blade could be assessed by applying various load conditions and different modeling methods in the future.

• 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.