• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.46-51
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• 2001

As a rule, in case of CFT for high-rise building, high strength concrete is required since it should have high fluidity, segregation resistance and large proportion of cement per unit considering the fi11ing beneath the diaphragm. However, regarding the low-rise building under 20 stories, it is somewhat difficult to use high strength concrete. This is a fundamental study to develop a concrete with normal strength and high fluidity for CFT of low-rise building, whose purposes are in speculating several kinds of changes in concrete's characteristics through various experiments and offering basic documents for practicalization in si to and production through mock-up test.

• Journal of Sensor Science and Technology
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• v.22 no.6
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• pp.439-443
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• 2013

A wireless optical fiber interferometer arterial pulse wave sensor system is developed for remote sensing. The wireless optical fiber sensor system consists of Zigbee communication modules and an optical fiber interferometer arterial pulse wave sensor. The optical fiber arterial pulse wave sensor is an in-line Michelson interferometer enclosed with steel reinforcement in a heat-shrinkable tube. The Zigbee communication modules are composed of an ATmega128L microprocessor and a CC2420 Zigbee chip. The arterial pulse waves detected by the optical fiber sensor were transmitted and received via the Zigbee communication modules. The experimental results show that the wireless optical fiber sensor system can be used for monitoring the arterial pulse waves remotely.

• 연구논문집
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• s.31
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• pp.149-156
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• 2001

Hydrogen damage affects carbon steel tubes in many fossil-fuel-fired boilers, often causing large tube ruptures that necessitate an immediate shutdown. Therefore, equipment handling high-temperature, high-pressure hydrogen must undergo careful periodic inspection because of its susceptibility to hydrogen attack. This paper describes the application of an ultrasonic technique for detecting the presence of hydrogen damage in utility boiler tubes. The accuracy of the technique has been shown in laboratory tests. However, it is difficult to evaluate hydrogen attack quantitatively by this technique, because ultrasonic wave is influenced by the test conditions and the material itself.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.3
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• pp.165-172
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• 2004

Compared with the hydroforming technology for steel, the hydroforming technology for aluminum has not been actively investigated. Recently, the hydroforming of high strength aluminum tubes has attracted great interest because of its good strength to weight ratio. In this study, front side member (FSM) is fabricated with the hydroforming of aluminum tube and the mechanical properties and dimensional accuracy of the hydroformed FSM is investigated. For hydroforming process, extruded aluminum tubes with ribs to improve the structural rigidity are used. To ensure the mechanical properties, the aluminum tubes are T6 heat-treated before hydroforming.

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1183-1191
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• 2001

The metallorganic chemical vapor deposition (MOCVD) method has been used to prepare TiO2 thin films for the degradation of hazardous organic compounds, such as 2-chlorophenol (2-CP). The effect of supporting materials and metal doping on the photocatalytic activity of TiO2 thin films also has been studied. TiO2 thin films were coated onto various supporting materials, including stainless steel cloth(SS), quartz glass tube (QGT), and silica gel (SG). Transition metals, such as Pd(II), Pt(IV), Nd(III) and Fe(III), were doped onto TiO2 thin film. The results indicate that Nd(Ⅲ) doping improves the photodegradation of 2-CP. Among all supporting materials studied, SS(37 ${\mu}m)$ appears to be the best support. An optimal amount of doping material at 1.0 percent (w/w) of TiO2-substrate thin film gives the best photodegration of 2-CP.

• International Journal of High-Rise Buildings
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• v.8 no.2
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• pp.83-94
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• 2019

Diagrid structures have emerged in recent decades as an innovative solution for tube tall buildings, capable of merging structural efficiency and aesthetic quality. This paper investigates the effect of the building slenderness (grossly quantified by means of the aspect ratio, i.e., the ratio between the height and the plan dimension) on the structural behavior and on the optimal design parameters of diagrid tall buildings. For this purpose, building models with different slenderness values are designed by adopting preliminary design criteria, based on strength or stiffness demands; in addition, a design method based on a sizing optimization process that employs genetic algorithms is also proposed, with the aim to compare and/or refine the results obtained with simplified approaches.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.1
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• pp.56-63
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• 2021

The feedwater ring is an assembly in steam generator internal piping, which distributes feedwater into the secondary side of the steam generator. It consists of an assembly of carbon steel piping, pipe fittings and J-nozzles which are inserted into the top of the feedwater ring and welded to the diameter of the ring. The feedwater ring at the attachment region of the J-nozzle may be susceptible to flow accelerated corrosion (FAC) due to flow turbulence which increases local fluid velocities. If a J-nozzle becomes a loose part, it can cause damage to tubing near the tube sheet. In this paper, the structural stress analysis for a wall thinned feedwater ring and integrity evaluations under assumed loading conditions are carried out in compliance with ASME B&PV SecIII, NB-3200.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.4
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• pp.383-391
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• 1987

An experimental investigation has been conducted to determine the flow pattern for two-component , two-phase mixtures which flow vertically upwards in concentric annuli based on the measurement for the local void fraction and the distribution of the local void fraction in various radial locations in the annular gap. The annular test section consists of a lucite outer tube whose inside diameter is 38mm and a stainless steel rod, The rod diameter is either :2mm,16mm or 20mm. It is demonstrated that the probability density function of the fluctuations in void fraction may be used as an flow pattern indicator and the local void fraction distribution depends on the flow pattern and radial location in the annular passage.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.33-42
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• 2004

Making use of SN steel in the building structure should be a prerequisite to adopt the design strength of said steel. As a preceding study, the material properties of STKN400B/490B tubes and SPAP235/325 and SPAR295 square pipes manufactured using SN400B/490B plates were evaluated. Compared with the yield and ultimate strengths of SN400B/490B plates, those of STKN400B/490B tubes increase. Nonetheless, the yield and ultimate strengths of STKN400B/490B tubes satisfied the design codes of STKN400B/490B tubes even though the tubes were fabricated via roll bending or press forming. On the other hand, the yield and ultimate strengths at the edges of SPAP235/325 square pipes did not satisfy the design codes based on the values at the sides. The maximum tensile and compressive residual stresses at the SN490B tube were equal to and 40% of the yield strength of the SN490B plate, respectively, In the case of the SPAP325 square pipe, both the maximum tensile and compressive residual stresses were 80% of the yield strength of the SN490B plate. The axial compressive loaded column test results snowed that the buckling strengths were not very different regardless of the mode of fabrication of STKN490B tunes. i.e., through roll bending or press forming. On the other hand, the buckling strength of the SPAP325 square pipe was higher than that of the built-up square pipe.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.35-45
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• 2013

The concrete-filled tube column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. It suggests that pipe should be produced by welding two sides together where two shapes are joined after a channel is pre-welded onto the three sides in order to form an internal diaphragm. The upper diaphragm of the connection used the horizontal plate and the lower diaphragm used the Vertical plate. This research performed 6 monotonic tension experiments describing the connection upside and downside in order to evaluate the structural capability of the offered connection. And the cyclic loading experiment was performed about 2 T-Type column to beam connections. As to the experimental result edge cutting geometry, there was no big effect. An increase in the number of holes of the plate ultimate strength was increased by 5% and The thickness of the plate increases, the maximum strength was increased by 4%. T-Type connections until it reaches the plastic moment showed a stable behavior.