• Steel and Composite Structures
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• v.16 no.2
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• pp.157-185
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• 2014

This paper examines the behaviour of two types of practical open beam-to-tubular column connection details subjected to combined moment, axial and/or shear loads. Detailed continuum finite element models are developed and validated against available experimental results, and extended to deal with flexural, axial and shear load interactions. A numerical investigation is then carried out on the behaviour of selected connections with different stiffness and strength characteristics under various load combination scenarios. The influence of applied levels of axial tensile or compressive loads on the bending stiffness and capacity is examined and discussed. Additionally, the interaction effects between shear forces and co-existing bending and axial loads are examined and shown to be comparatively insignificant in terms of stiffness and capacity in most cases. It is also shown that the range of connections considered in this paper can provide rotational ductility levels in excess of those required under typical design scenarios. Based on these findings, a simplified component-based representation is proposed and described, and its ability to represent the connection response under combined loading is verified using results from detailed numerical simulations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.829-835
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• 2010

This paper presents a disposable power generator for microfluidic devices; the power generator has a tubular PEMFC and a $H_2$ generator. The tubular PEMFC has a tubular MEA (diameter: 1.52 mm) that is supported by a spiral wire electrode. The $H_2$ generator supplied $H_2$ to the tubular PEMFC; $H_2$ was generated via the reaction of Al foil (27 mg) and 5 M NaOH (0.12 ml). The open circuit voltage and power density of a unit cell of the tubular PEMFC were 0.81 V and $16.4\;mW/cm^2$ (0.35 V), respectively. The $H_2$ generator generated 11.6 ml $H_2$ for 15min. The power generator was continuously operated for 15 min at 0.64 mW (0.71 V) and for 10 min at 1.06 mW (0.46 V). We experimentally verified that it is feasible to use the proposed power generator as a power source for microfluidic devices; in the experiment, an LED (2.5 mW; 1.8 V) was lit for 10 min by using three serially connected TPEMFCs and one $H_2$ generator.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.973-981
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• 2008

This document presents the JES(Joint Element Structure) method that has been adopted for the firs time in our country for the construction of the structure crossing under the railroad without open excavation. Front Jacking Method, Tubular Roof Construction Method, New Tubular Roof Method and Joint Element Structure Method are commonly used for the construction of structures crossing under the railroad. JES Method, frequently used in Japan recently, is a new method to construct the structures crossing under the railroad in a safe manner and in a relatively short period of time by utilizing the steel elements with the joints through which the load in the vertical angle to the axial direction is transferred to the next element. The elements are tied to each other through the joints to form the permanent walls of a Rahmen structure under the road without open excavation and without limitation to the length in a convenient way. Through the case study in the project of a Subway Box Culvert Improvement for the Gyeonguiseon Railroad in front of Yonsei University using the JES Method, the cost and period of construction in various types of soil is investigated compared to the Front Jacking Method. Furthermore, by analyzing the results of instrumentation measurements carried out throughout the construction, comparison between the actual displacement in the ground and the predicted displacement in the design is made to provide the considerations to be counted for the design. In conclusion, comparison in the field of economic feasibility, constructability and safety between the JES Method and Front Jacking Method, which is most frequently adopted in our country at present, is made to present the JES Method as a new alternative for the non-open excavation construction method for the structures crossing under the railway.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.05a
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• pp.115-116
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• 2001

본 연구에서는 이온 크로마토그래피로 환경오염물질들을 분석하고자 할때의 단전들을 해소하기 위하여 모세관 컬럼 이온 크로마토그래피를 개발하였다. 모세관 컬럼은 두가지 형태로 개발하였는데 하나는 packed capillary 컬럼이며 다른하나는 open tubular capillary 컬럼이다. 또한 위와 같이 모세관 컬럼을 개발하여 사용하게됨을써, 부수적으로 펌프, 시료주입기, 억압장치 그리고 전도도 셀 등을 모두 적은 부피를 다룰 수 있는 구조로 바꾸어 주었다. 따라서 본 연구의 결과로 미량환경오염 물질의 분석에 모세관 컬럼 이온크로마토그래피를 이용할 수 있는 가능성을 확인할 수 있었고, 나아가 이온 크로마토그래피의 소형화로 현장에서 직접 분리, 분석을 할 수 있으리라 기대된다.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.229-236
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• 2022

In this study, a model experiment and field experiment was conducted to introduce the optimal tensile force when constructing a non-open cut tunnel according to the ground conditions of sandy soil. CMR (Concrete Modular Roof) method is economical because of the high precision and excellent durability, and corrosion resistance, and the inserted parts can be used as the main structure of a tunnel. In addition the CMR method has a stable advantage in interconnection because the concrete beam is press-fitted compared to the NTR (New Tubular Roof) method, and the need for quality control can be minimized. The ground conditions were corrected by adjusting the relative density of sandy soil during the construction of non-open cut tunnels, and after introducing various tensile forces, the surface settlement according to excavation was measured, and the optimal tensile force was derived. As a result of the experiment, the amount of settlement according to the relative density was found to be minor. Furthermore, analysis of each tensile force based on loose ground conditions resulted in an average decrease of approximately 22% in maximum settlement when the force was increased by 0.8 kN per segment. Considering these results, it is indicated that more than 2.0 kN tensile force per segment is recommended for settlement of the upper ground.

• Journal of the Korean Electrochemical Society
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• v.12 no.4
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• pp.329-334
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• 2009

This study is to develop a fuel cell system applicable to an in situ NMR (Nuclear magnetic resonance) diagnosis. The in situ NMR can be used in real time monitoring of various reactions occurring in the fuel cell, such as oxidation of fuel, reduction of oxygen, transport phenomena, and component degradation. The fuel cell for this purpose is, however, to be operated in a specifically designed tubular shape toroid cavity detector (TCD), which constrains the fuel cell to have a tubular shape. This may cause difficulties in effective mass transport of reactants/products and uniform distribution of assembly pressure. Therefore, a new flow field designed in a particular way is necessary to enhance the mass transport in the tubular fuel cell. In this study, a tubular-shaped close-type flow field made of non-magnetic material is developed. With this flow field, oxygen is effectively delivered to the cathode surface and the produced water is readily removed from the membrane-electrode assembly to prevent flooding. The resulting DMFC (direct methanol fuel cell) outperforms the open-type flow field and exhibits $36\;mW/cm^2$ even at room temperature.

• Journal of Veterinary Clinics
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• v.26 no.6
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• pp.644-646
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• 2009

A 5-year-old intact male black gibbon (Hylobates concolor) was referred for evaluation of the right pelvic limb lameness following a fight against other black gibbons. Fractures of the right tibia and fibula were suspected on physical examination and palpation of the right pelvic limb, but no other injuries or abnormalities were detected. While the black gibbon was sedated, pelvic limb radiographs were taken, which revealed diaphyseal oblique fractures of the right tibia and fibula. Open reduction of the fractures was performed. The tibial fracture was repaired by use of an internal fixation technique that included a tubular dynamic compression plate and cortical screws secured along the craniomedial aspect of the tibia. There were no complications during the postoperative rehabilitation period. At 9 weeks, radiographs revealed that bridging callus was well formed over the cortices of the tibial and fibular fracture area. The cast was removed 9 weeks after surgery. The black gibbon exhibited no evidence of lameness and was released back into the group. Presently, there are no published reports of internal fracture fixation in a black gibbon where a tubular dynamic compression plate and cortical screws provided excellent stabilization of the tibia and complete fracture healing allowing normal ambulation.

• Steel and Composite Structures
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• v.49 no.5
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• pp.533-546
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• 2023

Cost-effective solutions provided by composite construction are gaining popularity which, in turn, promotes the appearance on the market of new types of composite sections that allow not only to take advantage of the synergy of steel and concrete working together at room temperature, but also to improve their behaviour at high temperatures. When combined with high performance materials, significant load-bearing capacities can be achieved even with reduced cross-sectional dimensions. Steel-reinforced concrete-filled steel tubular (SR-CFST) columns are one of these innovative composite sections, where an open steel profile is embedded into a CFST section. Besides the renowned benefits of these typologies at room temperature, the fire protection offered by the surrounding concrete to the inner steel profile, gives them an enhanced fire performance which delays its loss of mechanical capacity in a fire scenario. The experimental evidence on the fire behaviour of SR-CFST columns is still scarce, particularly when combined with high performance materials. However, it is being much needed for the development of specific design provisions that consider the use of the inner steel profile in CFST columns. In this work, a new experimental program on the thermo-mechanical behaviour of SR-CFST columns is presented to extend the available experimental database. Ten SR-CFST stub columns, with circular and square geometries, combining high strength steel and concrete were tested. It was seen that the circular specimens reached higher failure times than the square columns, with the failure time increasing both when high strength steel was used at the embedded steel profile and high strength concrete was used as infill. Finally, different proposals for the reduction coefficients of high performance materials were assessed in the prediction of the cross-sectional fire resistance of the SR-CFST columns.

• Steel and Composite Structures
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• v.23 no.1
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• pp.115-130
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• 2017

A new type of moment-resisting bolted connection was developed for use in composite steel- concrete construction to connect composite open section steel beams to concrete filled steel square tubular columns. The connection was made possible using anchored blind bolts along with two through bolts. It was designed to act compositely with the in-situ reinforced concrete slab to achieve an enhanced stiffness and strength. The developed connection was incorporated in the design of a medium rise (five storey) commercial building which was located in low to medium seismicity regions. The lateral load resisting system for the design building consisted of moment resisting frames in two directions. A major full scale test on a sub-assembly of a perimeter moment-resisting frame of the model building was conducted to study the system behaviour incorporating the proposed connection. The behaviour of the proposed connection and its interaction with the floor slab under cyclic loading representing the earthquake events with return periods of 500 years and 2500 years was investigated. The proposed connection was categorized as semi rigid for unbraced frames based on the classification method presented in Eurocode 3. Furthermore, the proposed connection, composite with the floor slab, successfully provided adequate lateral load resistance for the model building.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.691-695
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• 2002

A low temperature anode-supported tubular solid oxide fuel cell was developed. The anode-supported tube was fabricated using extrusion process. Then the electrolyte layer and the cathode layer were coated onto the anode tube by slurry dipping process, subsequently. The anode tube and electrolyte were co-fired at $140^{\circ}C$, and the cathode was sintered at $1200^{\circ}C$. The thickness and gas permeability of the electrolyte depended on the number of coating and the slurry concentration. Anode-supported tube was satisfied with SOFC requirements, related to electrical conductivity, pore structure, and gas diffusion limitations. At operating temperature of $800^{\circ}C$, open circuit voltage of the cell with gastight and dense electrolyte layer was 1.1 V and the cell showed a good performance of 450 mW/$\textrm{cm}^2$.