• Steel and Composite Structures
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• v.13 no.6
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• pp.571-586
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• 2012

The paper addresses some key issues related to the design of composite slabs with cold-formed profiled steel sheets. An experimental programme is first presented, involving six composite slab specimens tested with a view to evaluating Eurocode 4 (EC4) provisions on testing of composite slabs. In four specimens, the EC4-prescribed 5000 load cycles were applied using different load ranges resulting from alternative interpretations of the reference load $W_t$. Although the rationale of the application of cyclic loading is to induce loss of chemical bond between the concrete plate and the steel sheet, no such loss was noted in the tests for either interpretation of the range of load cycles. Using the recorded response of the specimens the values of factors m and k (related to interface shear transfer in the composite slab) were determined for the specific steel sheet used in the tests, on the basis of three alternative interpretations of the related EC4 provisions. The test results confirmed the need for a more unambiguous description of the m-k test and its interpretation in a future edition of the Code, as well as for an increase in the load amplitude range to be used in the cyclic loading tests, to make sure that the intended loss of bond between the concrete slab and the steel sheet is actually reached. The study also included the development of a special-purpose software that facilitates design of composite slabs; a parametric investigation of the importance of m-k values in slab design is presented in the last part of the paper.

• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.129-136
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• 2021

Radiation shields used in medical institutions mainly use lead to manufacture products and fitments. Although lead has excellent processability and economic efficiency, its use is being reduced due to environmental issues when it is disposed of. In addition, when used for a long time, there is a limit to using it as a shielding film, shielding wall, medical device parts, etc. due to cracking and sagging due to gravity. To solve this problem, copper, tin, etc. are used, but tungsten is mostly used because there is a difficulty in the manufacturing process to control the shielding performance. However, it is difficult to compare with other shielding materials because the characteristics according to the type of tungsten are not well presented. Therefore, in this study, a medical radiation shielding sheet was manufactured in the same process using pure tungsten, tungsten carbide, and tungsten oxide, and the particle composition and shielding performance of the sheet cross-section were compared.As a result of comparison, it was found that the shielding performance was excellent in the order of pure tungsten, tungsten carbide, and tungsten oxide.

• Composites Research
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• v.32 no.2
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• pp.113-119
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• 2019

The objective of this research is to study the mechanical and vibration characteristics of vibration damping aluminum panels for automotive parts. For this purpose, the test and simulation results of aluminum-resin hybrid materials and aluminum sheet materials were compared. Tensile strength and elastic modulus of the hybrid material were approximately 10% lower than aluminum sheet. Also, it was showed that the hybrid material have lower natural frequency than aluminum sheet, and it was confirmed that loss factor increases as the thickness of resin increases. Finally, it is confirmed that the test results and the analysis results are similar with each other and the performance prediction of the materials are possible by FEA.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.811-817
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• 2019

Radiation-therapy causes the adverse radiation effect. It is called osteoradionecrosis. A protein-therapy is carried out in order to cure osteoradionecrosis. The typical method of the protein-therapy is using BMP-2. Considering to bone damage, it is more important that maintains enough to circumstance regeneration for osteoblast differentiation on damage site of bone. Thus, this study is on a tissue regeneration to cure radiation critical damage. I observed that the formation of new regeneration bone by injection of collagen sheet BMP-2 on irradiated mouse. Consequently, I examined new bone formation with collagen sheet BMP-2 on irradiated mouse after 8weeks. Therefore I suggested that using collagen sheet BMP-2 which can be good for new bone regeneration effect on radiation side effect area.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.119-126
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• 2021

Radiation shielding clothing for medical institutions is used based on lead equivalent of 0.25 mmPb. However, this study intends to study the shielding suit that can guarantee the user's activity while considering the sensitivity of each part of the body. By manufacturing based on eco-friendly shielding material, it was attempted to solve the weight problem and environmental problem of existing lead aprons, and to present the same shielding performance as lead equivalent in thickness. The fabric of the produced shielding sheet was manufactured through a calendar process that adjusts the thickness of the shielding sheet from lead equivalent 0.12 mmPb to 0.32 mmPb. In addition, the usability evaluation of the manufactured shielding clothes was conducted for the subjects who were workers in medical institutions. As a result, the activity became easier and the weight was reduced by 0.26 kg. In the future, it is thought that it is necessary to improve the shielding suit design considering the activity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.567-576
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• 2023

In general, RC beam members are designed as flexural members, considering only the bending load. However, in actual buildings, axial and bending load are simultaneously applied due to the continuity between members. As a result, the bending strength of the RC beam member increases, but the displacement decreases, and cracks are mainly concentrated in the center of the beam. Therefore, in this study, the bending performance of both normal and strengthened RC beam using carbon fiber sheets subjected to combined axial and bending load was experimentally evaluated. The carbon fiber sheets were wrapped around the middle of the specimens, and axial and bending load were applied simultaneously to the beams. The magnitude of the axial force and the effects of carbon fiber sheet reinforcement on the deformed shape, bending strength, deflection, and ductility of the RC beams were analyzed. The results show that as the applied axial force increased, the maximum bending strength increased, but the ductility decreased 64%. The bending strength of the strengthened beams increased up to 27%, the maximum deflection decreased around 8% and the ductility increased by up to 43%.

• Transactions of Materials Processing
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• v.31 no.3
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• pp.129-135
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• 2022

The purpose of this study was to quantitatively evaluate the influence of hardness of tool materials on wear resistance in the sheet metal forming process. Punches used in the wear test were made of STD-11 and K340 tool material, and the tempering temperature was set to 530℃ and 500℃, respectively, to control the hardness of the tool materials. The punches mimic the shape of stamping tool of automotive body component to reflect its plastic deformation, and are designed to concentrate wear on the curvature region of punches. Progressive die and coil sheet were used to save time, cost, and raw sheet materials. By quantitatively measuring the wear depth of the punches, the wear behavior and mechanism of the punches were investigated, and characteristics of hardness and wear resistance according to tool materials and tempering temperatures were evaluated. Testing results indicate that the punch made of K340 tool steel with higher hardness had better wear resistance than that of STD-11 tool steel, and the hardness and wear resistance of tool steel were significantly impacted by the tempering temperature.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.431-439
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• 2016

This paper dealt with contents of the quality evaluation method of lattice girder utilizing non-destructive method. Quality evaluation of ordinary lattice girder is performed through the tensile strength test of structural steel and visual inspection. The tensile strength test of structural steel is performed by collecting samples of lattice girder brought into the site, during which lattice girder must be damaged to obtain sample. In addition to such disadvantage, tensile strength tester is not available at the site in most cases, requiring an inconvenient service from test certification agency. In addition, it is substituted by mile sheet issued during the production of structural steel, which inevitably lacks reliability. Furthermore, visual inspection at the site entails a problem of lack of reliability, thereby requiring a method of easily and quickly evaluating the quality of lattice girder without damaging the material. Accordingly, this study comparatively analyzed the yield strength of tensile strength test and the yield strength of instrumented indentation test with same sample. The test results ensured over 95% precision level for the instrumented indentation test, based on which a quality evaluation method based on instrumented indentation test that allowed onsite direct quality evaluation is proposed.

• Journal of Korea Association of Health Promotion
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• v.4 no.1
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• pp.1-11
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• 2006

"본 논문은 대한외과학회지 2006년 제70권제1호에 실렸던 논문으로 대한외과학회 편집위원회 승인을 득하고 본 협회지에 게재함. Purpose: Malnutrition has been frequently reported for patients on their admission to the hospital and it has been associated with an increase in morbidity, mortality and the length of the hospital stay. Although a number of screening tools have been developed to identify those patients at risk for malnutrition, there is no' gold standard' for defining malnutrition and the malnourished patients remain largely unrecognized. The aim of this study is to evaluate the efficacy of a nutritional screening tool for use in Dankook University Hospital. Methods Nutritional evaluation was performed for 53 patients who were admitted to the department of surgery and internal medicine between October and December 2004. The screening tool was completed by the ward nurse and the nutritional support team nurse on the same patients within24 hours of admission. The nutritional support team nurse performed the full assessment. The screening sheet included 4 questions regarding body mass index, recent unintentional weight loss, food intake and disease severity. Each answer was scored and a total of 5 was tested as the criterion fey malnutrition. The full assessment included current body weight, recent weight loss, triceps skinfold thickness, mid-arm muscle circumference, serum albumin)in and total lymphocyte count. Malnutrition was defined by 3 or more values below the reference values. The reliability of the screening tool was assessed using kappa statistic. Sensitivity, specificity and accuracy were calculated to evaluate the validity of the screening tool. The receiver operating characteristic(ROC) curve was drawn to choose a cutoff valve that maximizes sensitivity and specificity. Results' The level of agreement between the ward nurse and the NST nurse was good for BMI and food intake and moderate for weight loss and disease severity. The full assessment identified7 patients(13.2%) as malnourished. The screening sheet had a sensitivity of 86% and a specificity of 80%. According to the ROC curve, a score of 5 points provided the best validity. Conclusion The nutritional screening tool is reliable when completed by different observers and it is valid for nutritional assessment.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.214-221
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• 1999

Spot welding is very important and useful technology in fabriaction of the thin sheet structure such as the automobile, train and air craft, Because fatigue strength of the spot welding point is however considerably lower than base metal due to stress concentration at the nugget edge, reasonable fatigue strength evaluation of spot welded lap joint is very important to estimate the reliability and durability of th spot welded structure and to establish a criterion of ling life fatigue design. For reasonalbe fatigue strength evaluation, it is necessary to estimate the fatigue strength of spot welded lap joints, systematically. So far, many investigators have numerically and experimentally studied on the systematic fatigue strength estimation for various spot welded lap joints, and the methods suggested has been considerably accumulated. By the way, for applying them in practical fatigue design of the thin sheet structure fabricated by spot welding ,it is also necessary to verify their efficiency and reliability on the predicted results, Therefore, in this study, a statistical fatigue strength estimation method for spot welded lap joints was developed by using the Weibull probability distribution function. From the result, it was found that fatigue strength and fatigue life of the spot welded lap joints having various dimension were able to be statically predicted . And also, a reliable criterion for long life fatigue design of the spot welded lap joint could be established.