• Earthquakes and Structures
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• v.15 no.6
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• pp.667-685
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• 2018

In eccentrically braced steel frames (EBFs), the links are fuse members which enter inelastic phase before other structure members and dissipate the seismic energy. Based on the force-based seismic design method, damages and plastic deformations are limited to the links, and the main structure members are required tremendous sizes to ensure elastic with limited or no damage. Force-based seismic design method is very common and is found in most design codes, it is unable to determine the inelastic response of the structure and the damages of the members. Nowadays, methods of seismic design are emphasizing more on performance-based seismic design concept to have a more realistic assessment of the inelastic response of the structure. Links use ordinary steel Q345 (the nominal yielding strength $f_y{\geq}345MPa$) while other members use high strength steel (Q460 $f_y{\geq}460MPa$ or Q690 $f_y{\geq}690MPa$) in eccentrically braced frames with high strength steel combination (HSS-EBFs). The application of high strength steels brings out many advantages, including higher safety ensured by higher strength in elastic state, better economy which results from the smaller member size and structural weight as well as the corresponding welding work, and most importantly, the application of high strength steel in seismic fortification zone, which is helpful to popularize the extensive use of high strength steel. In order to comparison seismic behavior between HSS-EBFs and ordinary EBFs, on the basis of experimental study, four structures with 5, 10, 15 and 20 stories were designed by PBSD method for HSS-EBFs and ordinary EBFs. Nonlinear static and dynamic analysis is applied to all designs. The loading capacity, lateral stiffness, ductility and story drifts and failure mode under rare earthquake of the designs are compared. Analyses results indicated that HSS-EBFs have similar loading capacity with ordinary EBFs while the lateral stiffness and ductility of HSS-EBFs is lower than that of EBFs. HSS-EBFs and ordinary EBFs designed by PBSD method have the similar failure mode and story drift distribution under rare earthquake, the steel weight of HSS-EBFs is 10%-15% lower than ordinary EBFs resulting in good economic efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.175-181
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• 2019

In the case of a conventional single stage decompression regulator used for large depressurization in the hydrogen fuel cell system of a fuel cell electric vehicle (FCEV), problems can arise, such as pulsation, slow response, hydrogen brittleness, leakage, high weight, and high cost due to high decompression. Most of these problems can be overcome easily using two decompression mechanisms (two-stage structures). In addition, a wide outlet-pressure control range can be secured if an electronic solenoid is applied to the second decompression. Accordingly, it is necessary to improve the precision of the outlet pressure of a two-stage pressure-reducing regulator and develop techniques, such as leakage prevention, durability, light weight, and price reduction. Therefore, to improve the outlet pressure accuracy and prevent leakage, the structural part before and after decompression to improve the air tightness were divided and the analysis was carried out assuming that the valve part was closed (open ratio: 0%) after each initial internal pressure application.

• Journal of Korean Medicine for Obesity Research
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• v.20 no.2
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• pp.69-77
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• 2020

Objectives: In this study, we investigated the antiobesity and antidiabetic effects of polyherbal extract, DM2 consisting of Atractylodis Rhizoma, Anemarrhenae Rhizoma, Cinnamomi Cortex, and Moutan Radicles Cortex in high fat diet-induced obesity mice. Methods: DM2 extract was prepared with a hot water. Six-week-old male C57BL/6N mice were fed a high-fat diet (HFD) for 8 weeks and then administrated with DM2 extract (500 mg/kg, p.o.) for 4 weeks. The changes of physiological markers, body weight (BW), food and water intakes, and the levels of fasting blood glucose (FBG) were measured once a week for 4 weeks in mice. The the serum levels of glucose, insulin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol (T-CHO), triglyceride, and low density lipoprotein cholesterol in sera were measured in mice using autometic chemical analyzer and enzyme linked immunosorbant assay. We also observed the histological changes of liver and pancreatic tissues with Hematoxylin & Eosin staining. Results: In physiological change, the increases of BW, calorie intake, and FBG in HFD-induced obese mice were significantly decreased after administration of DM2 extract for 4 weeks. The decrease of water intake was significantly increased in DM2 extract-administrated mice. In serological change, the administration of DM2 extract in obesity mice was significantly decreased the serum levels of glucose, insulin, T-CHO, AST, and ALT levels. We also found that DM2 extract inhibited the increase of lipid droplets in liver and the structural destruction of pancreatic tissues in obesity mice. Conclusion: Our study demonstrated that DM2 extract has antiobesity antidiabetic effects with body weight loss, decrease of glucose and insulin levels, and lipid accumulation on liver tissue.

• Composites Research
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• v.35 no.5
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• pp.347-358
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• 2022

Carbon fiber is an excellent structural material, which has been proven in many industries, and the shipbuilding industry is no exception. In particular, in advanced maritime countries, special ships of the Navy and Coast Guard with carbon fiber composite hulls have already been deployed. In Korea, carbon fiber composite materials have been applied to a 10-ton class leisure craft or a 30-ton class patrol, but no research has been done on a hundred of tons or more vessels. In this study, the feasibility study of a 500-ton patrol vessel with a carbon fiber composite hull was conducted through an analysis of similar cases abroad. As a result, it was recognized that the developed hull can be reduced in weight by about 21% to 25% compared to the existing aluminum or FRP hull. It was also confirmed that this light-weight effect can induce the improvement of the maximum speed and the improvement of the operating range via simulations.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1054-1065
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• 2021

Objective: We implemented a novel resectable myocardial model for mock myectomy using a hybrid method of three-dimensional (3D) printing and silicone molding for patients with apical hypertrophic cardiomyopathy (ApHCM). Materials and Methods: From January 2019 through May 2020, 3D models from three patients with ApHCM were generated using the end-diastolic cardiac CT phase image. After computer-aided designing of measures to prevent structural deformation during silicone injection into molding, 3D printing was performed to reproduce anatomic details and molds for the left ventricular (LV) myocardial mass. We compared the myocardial thickness of each cardiac segment and the LV myocardial mass and cavity volumes between the myocardial model images and cardiac CT images. The surgeon performed mock surgery, and we compared the volume and weight of the resected silicone and myocardium. Results: During the mock surgery, the surgeon could determine an ideal site for the incision and the optimal extent of myocardial resection. The mean differences in the measured myocardial thickness of the model (0.3, 1.0, 6.9, and 7.3 mm in the basal, midventricular, apical segments, and apex, respectively) and volume of the LV myocardial mass and chamber (36.9 mL and 14.8 mL, 2.9 mL and -9.4 mL, and 6.0 mL and -3.0 mL in basal, mid-ventricular and apical segments, respectively) were consistent with cardiac CT. The volume and weight of the resected silicone were similar to those of the resected myocardium (6 mL [6.2 g] of silicone and 5 mL [5.3 g] of the myocardium in patient 2; 12 mL [12.5 g] of silicone and 11.2 mL [11.8 g] of the myocardium in patient 3). Conclusion: Our 3D model created using hybrid 3D printing and silicone molding may be useful for determining the extent of surgery and planning surgery guided by a rehearsal platform for ApHCM.

• Composites Research
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• v.36 no.1
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• pp.1-15
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• 2023

Demand for energy consumption reduction is increasing according to the development expectations of future mobility. Lightweight structural materials are known as a method to reduce greenhouse gas emissions and improve energy efficiency. In particular, fiber reinforced polymer composite (FRP) is attracting attention as a material that can replace existing metal alloys due to its excellent mechanical properties and light weight. In this paper, industrial applications and research trends of carbon fiber reinforced composites (CFRP, carbon FRP) and self-reinforced composites (SRC) were reviewed based on the reinforcement, polymer matrix, and manufacturing process. In order to overcome the expensive process cost and long manufacturing time of the epoxy resin-based autoclave method, which is mainly used in the aircraft field, mass production of CFRP-applied electric vehicles has been reported using a high-pressure resin transfer molding process including fast-curing epoxy. In addition, thermoplastic resin-based CFRP and interface enhancement methods to solve the recycling issue of carbon fiber composites were reviewed in terms of materials and processes. To form a perfect matrix-reinforcement interface, which is known as the major factor inducing the excellent mechanical properties of FRP, studies on SRC impregnated with the same matrix in polymer fibers have been reported. The physical and mechanical properties of SRC based on various thermoplastic polymers were reviewed in terms of polymer orientation and composite structure. In addition, a copolymer matrix strategy for extending the processing window of highly drawn polypropylene fiber-based SRC was discussed. The application of CFRP and SRC as lightweight structural materials can provide potential options for improving the energy efficiency of future mobility.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.1
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• pp.83-85
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• 2007

A glycine and proline-rich antibacterial protein was cloned from larvae of a beetle, Protaetia brevitarsis. The DNAs encoded a deduced propeptide of 127 amino acid residues with predicted molecular weight of 14.0 kDa and PI of 7.89. Structural analysis of this protein indicated the presence of a recognition sequence for the cleavage site within the constitutive secretory pathway(Arg-Xaa-Lys/Arg-Arg), suggesting that mature portion(72 amino acid residues) is produced by cleavage of signal peptide and propeptide from 127 amino-acid-long precursor protein. Mature portion sequence of this protein showed 72% similarity to that of Oryctes rhinoceros Rhinocerosin and 91% to that of Holotrichia diomphalia holotricin 2. The mRNA expression was reached the highest level at 4 hrs after E. coli injection and then declined gradually.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.515-525
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• 2000

The purpose of this paper was to develop size & shape optimization programming algorithm of plane trusses. The optimum techniques applied in this study were extended penalty method of Sequential Unconstrained Minimization Techniques(SUMT) and direct search method with multi-variables proposed by Hooke & Jeeves. Upper mentioned two methods were used iteratively at each level of size and shape optimization routines. The design variables of size optimization were circular steel tube(structural member) diameter and thickness, those of shape optimization were joint coordinates, and the objective function was represented as total weight of truss. During the optimum design, two level procedures of size and shape optimization were interacted iteratively until the final optimum values were attained. At the previous studies about shape optimization of truss, the member sectional areas and coordinates were applied as design variables. So that they could not apply the buckling effect of compression member. In this paper, actual sizes of member and nodal coordinates are used as design variables to consider the buckling effect of compression member properly.

• The Journal of Internal Korean Medicine
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• v.29 no.4
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• pp.1025-1036
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• 2008

Objectives : The aim of present study was to investigate recovery effects of gypsum, which has been used clinically in diabetes therapy. Methods : We established three groups, normal, control, and gypsum, and assigned 6 rats to each group. The normal group was not treated by any process and fed normal saline. The control & gypsum groups were administered streptozotocin(STZ) to induce diabetes. Gypsum extract was orally administered to the gypsum group for 10 days. After 8 weeks, the rats were sacrificed and their body weight, 24hrs urinary protein excretion, glucose, albumin, BUN, creatinine, total-cholesterol, LDL-cholesterol, triglyceride in blood, level of glycation end-product (AGE) and transforming growth factor ($TGF-{\beta}1$) in serum were measured. Morphological profiles and morphometric studies of the kidney cortex. renal transforming growth factor ($TGF-{\beta}1$) expression, macrophage/monocyte antigen (ED-1), and type IV collagen expression were studied. Results : The following results were obtained. The protein amount in urine per 24hrs of the gypsum-treated group as compared to the control was significantly reduced. The BUN and creatinine level in serum of the gypsum-treated group as compared to the control was significantly inhibited. The construction change in the kidneys of the gypsum-treated group as compared to the control was significantly inhibited. The factor of the gypsum-treated group as compared to the control was significantly inhibited. which induced the structural change in the kidneys. Conclusions : The above results suggest that gypsum partially improved kidney function.