• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.42-51
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• 2000

The performances of the simple expansion, perforated tube, and conical-connector type as an exhaust muffler are shown in this study. Applying a model in which the method of four-pole parameter is used makes theoretical estimation of the insertion loss. Experiment is performed for the measurement of the insertion loss under four cases according to the variation of the tail pipe length. By comparing the theoretical prediction with the experimental results, the validity of the modeling using the method of four-pole parameter is verified. The personal computer simulation programs for the above mentioned theory on the muffler design have been developed and exhaust sound level measurements have been carried out for simple expansion muffler, conical-connector muffler, perforated tube mufflers and the combined type of conical-connector and simple expansion muffler. The measured results for attenuation characteristics of noise for each muffler are compared with the computed theoretical results to verity the confidence and applicable limits of the theoretical equation derived.

• Journal of KIBIM
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• v.5 no.4
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• pp.47-52
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• 2015

This paper presents a case study using Building Information Modeling (BIM) for planning, simulating, and implementing complex site logistics in a headquarter office building construction project in Silver Spring, MD. As part of the project a prefabricated 92ft structural tube steel pedestrian connector bridge was installed between two adjacent buildings in the city of Silver Spring, MD. There were multiple significant challenges to deliver, offload, prepare, and install the connector bridge safely, on time, and with the minimum disturbances to the neighbors. BIM was of the foremost importance to visualize, simulate, analyze, improve, and communicate the site logistics plan from delivery to installation of the connector bridge. As a result of the effort, GC of the project was able to prepare a highly detailed plan, communicate it effectively to all stakeholders, and flawlessly execute the work as planned. This case study would provide a useful reference for contractors who are seeking a better planning method that enables generation of more accurate, implementable, optimized plans for complex site logistics.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1488-1489
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• 2007

This paper described the current rating methodology of high voltage connectors used for high efficient vehicles. Typically, temperature rise at rated current has been used to rate power contacts in automotive connector. However, for automotive applications, they are required to meet severe environmental conditions and high connector reliability. Therefore, it is very important to rate correctly an allowable current of automotive connector. We have measured the contact characteristics through current cycling at room temperature and at high temperature, as well as temperature rising and current carrying capacity by de-rating. From the above results, we have developed high reliable contacts with about 80 Amperes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.2
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• pp.131-137
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• 2000

In order to evaluate the design shear strength of composite slabs with truss-shaped shear connectors(TSC), a series of push-out tests on several types of specimens was carried out. The test results for the two parameters of bearing area and solid angle of the connector were compared to obtain the design shear force of the truss-shaped connectors. The results obtained from this study are as follows: (1) The slip-coefficients of TSC ranges from 0.87 to 3.12(${\times}10^6kgf/cm$). (2) The slip stiffness and the shear strength of TSC with $60.6cm^2$ bearing area are greater than those with $14.6cm^2$. (3) For estimating the allowable shear force of TSC, a design equation that is based on the bearing strength of the connector is suggested. (4) The mean safety factors of the critical force and the ultimate force are 2.38 and 4.62. respectively.

• Structural Engineering and Mechanics
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• v.80 no.5
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• pp.595-608
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• 2021

To investigate the mechanical behavior of large stud shear connector embedded in hybrid fiber-reinforced concrete (HFRC), a refined 3D nonlinear finite element (FE) model incorporating the constitutive model of HFRC was developed using ANSYS. Firstly, the test results conducted by the authors (He et al. 2017) were used to validate FE model of push out tests. Secondly, a total of 27 specimens were analyzed with various parameters including fiber volume fractions of HFRC, diameter of studs and HFRC strength. Finally, an empirical equation considering the contribution of steel fiber (SF) and polypropylene fiber (PF) was recommended to estimate the ultimate capacity of large stud shear connector embedded in HFRC.

• Steel and Composite Structures
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• v.49 no.2
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• pp.197-213
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• 2023

To investigate the static properties of large high strength bolt shear connector in hybrid fiber-reinforced concrete (HFRC) and normal concrete (NC), eight push-out test specimens with single/double nut and HFRC/NC slabs were designed and push-out tests were conducted. A fine 3D nonlinear finite element (FE) model including HFRC constitutive model was established by using ANSYS 18.0, and the test results were used to verify FE models of the push-out test specimens. Then a total of 13 FE models were analyzed with various parameters including fiber volume fractions of HFRC, bolt diameter and thickness of steel flange. Finally, the empirical equations considering the contribution of polypropylene fiber (PF) and steel fiber (SF) obtained from the regression of the test results and FE analysis were recommended to evaluate the load-slip curve and ultimate capacity of the large high strength bolt shear connector embedded in HFRC/NC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.481-492
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• 2018

The steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, the SPC beam was composed of folding steel plates and concrete, without a headed stud. The folding steel plate was assembled by a high strength bolt instead of welding. To improve the workability in a field construction, a hat-shaped cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode to analyze the flexural strength of the SPC beam using a cap as the shear connector. Five specimens with shear connector types, protrusion length, and different thickness of steel plates were constructed and tested. The experimental results were analyzed through the relationship between the shear strength ratio and flexural strength in KBC 2009. The test results showed a shear strength ratio of more than 40 %. In the case of using a cap-like specimen as the shear connector, the flexural strength was 70% of the value calculated as a fully composite beam. In addition, the cap showed a smaller shear strength than the stud, but the cap served as a shear connection. When the thickness of the steel plate was taken as a variable, the steel plate exhibited a bending strength of approximately 70% compared to a fully formed steel plate, and exhibited similar deformation performance. Local buckling occurred due to incomplete composite behavior, but local buckling occurred at a 5% higher strength for a relatively thick steel plate. The buckling width also decreased by 15%.

• Journal of Advanced Navigation Technology
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• v.6 no.3
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• pp.195-202
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• 2002

Recently, as the range of mobile communication services is extended, the interference between adjacent base-stations is increased. Nowdays, one of the important factors causing interference is IMD (Inter-Modulation Distortion) problems. Not only active IMD but also passive IMD effects must be considered to design a CDMA system. In this study, we design and implement 7/16" DIN connectors which have a various intensity of surface illumination, thickness and quality of plating material to analyze the effects of PIMD. And propose the methods for improving the PIMD characteristics: First, it is more profitable to use the metal which has good intensity of surface illumination where most of all electric currents passes through it. Secondly, we should plate metals more than $5{\mu}m$ for RF energy enough to propagate in a medium. Thirdly, it is necessary to select a metal having high conductivity and specific heat to protect the aging phenomenon of plate material. And it is required to develop a new plating material to replace the current materials, such as the alloy of three components for cost reduction. We have to know that the plate which has intensity of surface illumination 6 S and the thickness of plating material $5{\mu}m$ satisfy the domestic PIMD specification (KTF) -150 dBc, regardless of the plate material in case of 7/16" DIN connector.

• Journal of Korean Society of Steel Construction
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• v.28 no.6
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• pp.467-476
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• 2016

For the connections between modular units in modular buildings, the bolted joints with connector plates are used commonly. The strength of structure is determined by the weakest part of structure and the connections may be weaker than the members being joined. Therefore, to check the safety of modular building, the structural performance of connections between modular units as well as that of beam-to-column connections should be evaluated. In this study, the behavior of module to module connection with straight and cross shaped connector plates is investigated by lateral cyclic tests according to KBC2009 0722.2.4 which shall be conducted by controlling the story drift angle in the width and the longitudinal direction respectively. All of test results generally show the stable ductile behavior up to 0.04rad drift levels and the tests in longitudinal direction show a superior energy dissipation per cycle in each of the load steps. However, the straight shaped connector plates have the degradation of stiffness with cyclic loading and the larger drift angle of column than the cross shaped connector plates.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.55-69
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• 1987

The purpose of this study was to evaluate the stress distributions of the fixed partial denture with five unit intermediate abutment. This fixed partial denture was attached to a three dimensional photoelastic epoxy resin model. Three dimensional photoelastic models were used, with the stress areas recorded photographically. A vertical load was applied to the second molar, which is the most posterior abutment of the fixed partial denture. Similarly, a vertical load was applied to the first molar because this tooth receives the heaviest masticatory load. These loads were added to two types of fixed partial denture. the rigid connector, and the nonrigid connector which was connected on the distal side of the intermediate abutment by a key and keyway device. After the stress patterns in surrounding tissues were observed, the following conclusions were as follows: 1. When the vertical load was applied to the first and second molars on the occlusal surfaces, the surrounding tissues of the roots of the canine, the second premolar, and the second molar were all compressive stresses. 2. When the vertical load was applied on the occlusal surface of the second molar, the tissue surrounding the roots of the canine, the second premolar, and the second molar all showed more stresses with the nonrigid connector than with the rigid connector. 3. When the vertical load was applied to the occlusal surface of the first molar, the stress concentration on the canine and the second molar was similar, whether the rigid or nonrigic connectors were used. However, on the second premolar, the stress concentration shown by the nonrigid connector was noticeably more than that shown by the rigid connector. 4. Whether the rigid or nonrigid connectors were used, when the load was placed on the first molar, the stress concentration on the canine and the second premolar was greater than that observed for the second molar. When the load was placed on the second molar, the load affected the second molar more than the canine and the second premolar.