• Computers and Concrete
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• v.13 no.4
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• pp.517-529
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• 2014

In order to increase the load carrying capacity and/or increase the service life of existing circular reinforced concrete bridge columns, Carbon Fiber Reinforced Polymer (CFRP) composites could be utilized. Transverse wrapping of circular concrete columns with CFRP sheets increases its axial and shear strengths. In addition, it provides good confinement to the concrete column core, which enhances the bending and compressive strength, as well as, ductility. Several experimental and analytical studies have been conducted on CFRP strengthened concrete cylinders/columns. However, there seem to be lack of thorough investigation of the effect of elevated temperatures on the response of CFRP strengthened circular concrete columns. A concrete confinement model that reflects the effects of elevated temperature on the mechanical properties of CFRP composites, and the efficiency of CFRP in strengthened concrete columns is presented. Tensile strength and modulus of CFRP under hot conditions and their effects on the concrete confinement are the primary parameters that were investigated. A modified concrete confinement model is developed and presented.

• Advances in concrete construction
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• v.4 no.4
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• pp.243-261
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• 2016

This research study focuses on utilizing sandstone which is overburden waste rock in coal mines to use in concrete as a replacement of fine aggregate. Physical properties of sandstone like water absorption, moisture content, fineness modulus etc., were found to be similar to conventional fine aggregate. Scanning Electron Microscope (SEM) analysis was carried out for analysing elemental composition of sandstone. There was no sulphur content in sandstone which is a good sign to carry the replacement. Fine aggregate was replaced with sandstone at 25%, 50%, 75% and 100% by volume and moulds of concrete cubes and cylinders were prepared. Compressive strength of concrete cubes was tested after 3, 7 and 28 days and split tensile & flexural strength was determined after 28 days. The strength was found to be increasing marginally with increase in sandstone content. Fine aggregate that was replaced by 100% sandstone gave highest strength among all the replacements for the compressive, split tensile and flexural strengths. Though increase in strength was marginal, still sandstone can be an effective replacement for sand in order to save the natural resource and utilize the waste sandstone.

• Economic and Environmental Geology
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• v.18 no.2
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• pp.159-166
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• 1985

The computation of gravity anomalies by multi pole expansion is derived and compared with exact calculation for right rectangular prisms and right circular cylinders. For sources near field points, the multipole expansion results in a better approximation in volume integrals than in surface integrals. Nonetheless two approximate methods are coincident in the far-field of the general geophyical prospecting.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.212-214
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• 2015

독성가스는 반도체, LCD, 태양전지 등 첨산 산업 발달로 그 수요가 증가하고 있으나, 독성가스 용기 무단폐기 등 관리 및 유통에 대한 체계가 열악한 실정이다. 독성가스를 제조 유통하는 시설이 2013년 기준으로 2,774개소가 있으며, 2012년 가스사용량은 2010년 대비 62.5% 급증하였다. 대학교, 연구소 등 사용량은 적으나 독성가스를 사용하지만 고압가스안전관리법의 검사 대상에서 제외되는 기관도 4천개 이상이 되는 상태에서 이에 대한 유통 이력 추적 관리는 매우 중요한 상태이다. 이에 따라 본 연구에서는, RFID를 이용하여 독성가스 용기의 제조, 유통, 충전 및 폐기 전 영역에서 이력정보를 관리하는 독성가스 용기 유통 이력추적관리기술을 개발하였으며, 본 기술을 통하여 투명하고 추적 가능한 독성가스 용기 관리 체계를 갖추었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.1-16
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• 1993

It is widely recognized that exhaust emissions, fuel economy and engine torque are affected by engine temperature, and logic would suggest that a cooling system offering a better compromise of engine temperature would improve both overall engine performance and economy. Author measured coolant temperature of some parts and flow rate which are necessary to heat transfer in a engine. And Author determined parameters necessary for the optimum design of a thermostat to keep the best engine performance ; determined the optimum operating temperature of electric cooling fan. A summary of this study is followed. 1. Study of the effects of cooling condition to combustion character in a engine. 2. Analyze of heat transfer surrounding engine cylinders. 3. Study of the effects of cooling character to engine heat rejection, determination of the optimum collant temperature for keeping the optimum engine performance and determination of the optimum design of a thermostat for keeping that temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.49-59
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• 1993

A new signal processing technique is applied to four-cylinder spark and compression ignition engines for the diagnosis of power faults inside the cylinders. This technique utilizes two-sided directional power spectra(예S) of complex vibration signals measured from engine blocks as the patterns for engine cylinder power faults. The dPSs feature that they give not only the frequency contents but also the directivity of the engine block motion. For the automatic detection/diagnosis of cylinder power faults, pattern recognition method using multi-layer neural networks is employed. Experimental results show that the sucess rate for diagnosis of cylinder power faults using dPSs is higher than that using the conventional one-sided power spectra. The proposed technique is also tested to check the robustness to the sensor position and the engine rotational speed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.533-534
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• 2006

In this paper we propose a new model of a mini-pump with peristaltic motion and present the results of the finite element analysis of an electromagnetic micro actuator. The mini-pump consists of three diaphrams made of PDMS, three permanent magnets in cylinders, printed copper coils on glass substrates, and input and output port. The size of the mini-pump is $14\;{\times}\;40\;{\times}\;5.4$ mm3 and the permanent magnet diameter 6.2 mm $\times$ thickness 2 mm. The electromagnetic force applied on the magnet was about 0.84 N when the current of coils was 1 A, then the maximum displacement of the PDMS diaphram was about 2mm.

• Macromolecular Research
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• v.16 no.4
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• pp.267-292
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• 2008

Block copolymers that two or more polymer chains are covalently linked have drawn much attention due to self-assembly into nanometer-sized morphology such as lamellae, cylinders, spheres, and gyroids. In this article, we first summarize the phase behavior of block copolymers in bulk and thin films and some applications for new functional nanomaterials. Then, future perspectives on block copolymers are described.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.198-201
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• 2000

Using the Finite-Difference Time-Domain (FDTD) method that analyzes the Maxwell equations in time domain, we simulated the characteristics of optical wave propagation and defect modes in two-dimensional photonic crystals composed of dielectric cylinders located on triangular, square, and honeycomb lattices. In particular, we investigated the properties of defect modes as the permittvity of the defects is varied. aried.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.159-164
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• 2006

In recent, the marine engine of a large size is being realized a lower speed, longer stroke and a small number of cylinders for the energy saving. Consequently the variation of rotational torque became larger than former days because of the longer delay-time in fuel oil injection process and an increased output per cylinder. It was necessary that algorithms have enough robustness to suppress the variation of the delay-time and the parameter perturbation. This paper shows the structure of hybrid F-NFC against the delay-time and the perturbation of engine parameter as modeling uncertainties, and the design of the robust speed controller by hybrid F-NFC for the engine. And, The Parameter values of linear equation are determined by RC-GA for F-NFS. The hybrid F-NFC is combined the F-NFC and PID controller for filling up each.