• Wind and Structures
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• 제4권4호
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• pp.279-298
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• 2001

The greatest suction on the cladding of flat roof low-rise buildings is known to occur beneath the conical vortices that form along the roof edges for cornering winds. In a companion paper, a model of the vortex flow mechanism has been developed which can be used to connect the surface pressure beneath the vortex to adjacent flow conditions. The flow model is experimentally validated in this paper using simultaneous velocity and surface pressure measurement on a 1 : 50 model of the Texas Tech University experimental building in a wind tunnel simulated atmospheric boundary layer. Flow visualization gives further insight into the nature of peak suction events. The flow model is shown to account for the increase in suction towards the roof corner as well as the presence of the highest suction at wind angles of $60^{\circ}$. It includes a parameter describing vortex suction strength, which is shown to be related to the nature of the reattachment, and also suggests how different components of upstream turbulence could influence the surface pressure.

• Structural Engineering and Mechanics
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• 제55권4호
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• pp.687-702
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• 2015

A method based on derivatives of eigen-parameters is presented for damage detection in discrete systems with dampers. The damage is simulated by decrease on the stiffness coefficient and increase of the damping coefficient. In the forward analysis, the derivatives of eigen-parameters are derived for the discrete system. In the inverse analysis, a derivative of eigen-parameters based model updating approach is used to identify damages in frequency domain. Two numerical examples are investigated to illustrate efficiency and accuracy of the proposed method. Studies in this paper indicate that the proposed method is efficient and robust for both single and multiple damages and is insensitive to measurement noise. And satisfactory identified results can be obtained from few numbers of iterations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.532-535
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• 2000

We have fabricated a sensor system for on-line monitoring the oxygen permeability and diffusivity of six different polymer films using the miniaturized 6 cathode(Ag)-single anode(Ag/AgCl) type hexagonal oxygen electrode. This system consists of multiple input front-end electronics, signal conditioning circuit using the embedded microcontroller 80C196KC, PC interface circuit and PC with the OS for microcontroller and the operating program for this system. The digital low-[ass filter was programmed and the simulated filter characteristics were enough to eliminate the noise from sensor signal. According to the experimental results, the linearity coefficients of the output voltage to oxygen partial pressure for each sensor electrode of six cathode type oxygen sensor are 0.998, 0.997, 0.998, 0.997, 0.997, 0.997 respectively, and the response times are all within 4 minutes.

• Proceedings of the KIEE Conference
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1170-1172
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• 1996

Analog-digital converter boards for use in personal computers have recently being improved markedly, many kinds of high speed(1 MHz - 10 MHz sampling rale) and over 12-bit vertical resolution A/D boards released. It can be applicable to high frequency magnetic measurements. In measurement of magnetic properties of high frequency, digitizing oscilloscope or trasient recorder are being used. but, those price are often expensive, we constructed PC controlled A-C B-H loop tracer that can measure Bs, Br, He, permeability and may be applied about 100 Hz - 20 kHz range. it use IBM PC compatible 1 M Sample/s, 12 bit A/D converter board with SSH(Simultaneous Sample and Hold).

• Journal of Powder Materials
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• 제11권3호
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• pp.242-246
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• 2004

FePt nanoparticles for high-density magnetic recording media were synthesized by the simultaneous chemical reduction of Fe(acac) $_2$ and Pt(acac) $_2$ with 1,2-hexadecanediol as the reducing reagent. TEM images showed that the shape of as-synthesized FePt nanoparticle was spherical and average particle size was 3 nm. Also, SAD pattern showed that crystal structure was disordered FCC (face centered cubic). These FCC structured nanoparticles were transformed FCT (face centered tetragonal) structure by annealing at 55$0^{\circ}C$ for 30 min in Ar atmosphere. XRD analysis revealed that as-synthesized FePt nanoparticles were transformed from disordered FCC to ordered FCT. Finally, the coercivity of 2 kOe for FePt nanoparticles with FCT structure was obtained by VSM measurement.

• Bulletin of the Korean Chemical Society
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• 제12권1호
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• pp.87-92
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• 1991

A dual capillary column system is described for the simultaneous measurement of retention index (RI) and area ratio (AR) values of each peak on two capillary columns of different polarity, DB-5 & DB-1701. Both capillary columns were connected to a common splitless injector via a deactivated fused-silica capillary tubing of 1 m length and a 'Y' splitter, the dead volume effect of which was found to be negligible. RI and AR were measured with high reproducibility(${\leq}$0.05% RSD) and with high accuracy (<10% RE), respectively. When applied to the test samples of the organic acid mixture, each acid was positively identified by the combined computer RI library search-AR comparison.

• ETRI Journal
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• 제43권4호
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• pp.594-602
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• 2021

Recently, quantitative and repetitive inspections of the old urban area were conducted because many structures exceed their designed lifetime. The health of a building can be validated from the condition of the outer wall, while the slant angle of the wall widely serves as an indicator of urban regeneration projects. Mostly, the inspector directly measures the inclination of the wall or partially uses 3D point measurements using a static light detection and ranging (LiDAR). These approaches are costly, time-consuming, and only limited space can be measured. Therefore, we propose a mobile mapping system and automatic slant map generation algorithm, configured to capture urban environments online. Additionally, we use the LiDAR-inertial mapping algorithm to construct raw point clouds with gravity information. The proposed method extracts walls from raw point clouds and measures the slant angle of walls accurately. The generated slant angle map is evaluated in indoor and outdoor environments, and the accuracy is compared with real tiltmeter measurements.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.250-255
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• 1993

A dual capillary column system is described for the simultaneous analysis of a given sample and measurement of retention index (RI) and area ratio (AR) values of each peak on two capillary columns of different polarity, DB-5 & DB-1701 from a single injection. Both capillary columns were connected to either a splitless injector or an on-column injector via a deactivated fused-silica capillary tubing of 1 m length and a 'Y' splitter. Both injection modes allowed to measure RI and AR values with high reproducibility (<0.01% RSD) and high accuracy (<10% RE), respectively with the exception that the trace and high boiling solutes required the on-column mode for the accurate quantification and AR comparison. When the dual capillary column system in on-column injection mode was applied to the blind samples containing organic acids, each acid was positively indentified by the combined computer RI library search-AR comparison.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.615-616
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• 2022

Indoor positioning technology is being used in various application services due to the spread of smart devices. In addition to precisely positioning the location, simultaneous positioning of multiple users has been raised as a new problem. In addition, providing Internet services simultaneously with location measurement is essential for use in various applications. This paper aims to solve both of these problems by designing and implementing an indoor positioning system with the IEEE 802.11az standard

• The Bulletin of The Korean Astronomical Society
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• 제46권1호
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• pp.27.4-28
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• 2021

Since the first direct detection of the gravitational waves in 2015, more than 50 events coming from the merging of compact binaries composed of black holes and neutron stars have been observed. The simultaneous detection of gravitational waves and electromagnetics waves from the merging of neutron stars opened up multi-messenger astronomy. The forthcoming observations with better sensitivity by the network of ground based detectors will enrich the gravitational wave source populations and provide valuable information regarding stellar evolution, dynamics of dense stellar systems, and star formation history across the cosmic time. The precision of the Hubble constant from the distance measurement of gravitational sources will improve with more binary neutron star events are observed together with the aftweglows. I will also briefly cover the expected scientiic outcomes from the future detectors that are sensitive to much lower frequenies than current detectors.