• Computational Structural Engineering
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• v.5 no.3
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• pp.105-112
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• 1992

The design of reactor internals requires the accurate vibration characteristics of each component for subsequent dynamic structural response analysis. For Korean standard nuclear power plant some modifications on the Control Element Assembly shroud from the reference design have been made. Since the shroud is complex in geometry having an array of vertical round tubes and webs in a square grid pattern, and being tied down by preloaded tie rods into position, it is planned to perform a vibration measurement program consisting of both experimental and analytical modal studies upon that component. To determine the proper test conditions, the pre-test analysis has been performed using the general purpose structural analysis program ANSYS. Also the effects of the number of master degrees of freedom, holes in the web and tie-rod preload on the natural frequencies are examined prior to the pre-test analysis. After decision of appropriate finite element model, frequency analysis and harmonic analysis are performed and ideas for the test conditions such as the number of measurement points, their locations, measurement frequency range and the excitation force level are determined.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.1 s.307
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• pp.1-6
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• 2006

The noncontact optical sensor using the hologram laser and automatic power controller is developed to measure a thickness of transparent objects and achieve excellent performance. Due to the contact between the tip of the sensor and the surface of objects, the tip is abraded. In addition the casting glass under high temperature results in extending the size of sensor body. The accuracy of the sensor is degraded due to these reasons. In this paper, to overcome these problems, we proposed a low cost non-contact optical sensor that is composed of a hologram laser unit used for optical pickup of CD player and a plastic lens. Therefore the problems caused by the contact sensor are solved by using the noncontact sensor. The noncontact sensor has to move toward the objects and obtain the focus error signal to measure a position of transparent objects. While the internal temperature of the sensor is controlled under ${\pm}0.1^{\circ}$, many trials shows ${\pm}2{\mu}m$ measurement error as excellent performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.873-881
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• 2002

In this paper, the rectangular reflector antenna with 8-dipole array for PCS band (1,750 MHz ~ l,870 MHz) and IMT-2000 band(1,885 MHz ~ 2,200 MHz) is designed and the radiation characteristics are analyzed using the method of moments and HFSS(High Frequency Structure Simulator). To verify the analysis results, rectangular reflector antenna with 8-dipole array is fabricated and the calculated results are compared with the measured results. The measured results show good agreement with the calculated results. As a result of measurements, bandwidth(VSWR< 1.5) of 450 MHz is achieved at PCS and IMT-2000 band and gain is 16 dBi. The designed antenna can be used as the base station antenna for PCS/IMT-2000.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.405-412
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• 2008

This study was aimed to investigate whether an oxygen inhibition layer (OIL) is essential for the interfacial bonding between resin composite layers or not. A composite (Z-250, 3M ESPE) was filled in two layers using two aluminum plate molds with a hole of 3.7 mm diameter. The surface of first layer of cured composite was prepared by one of five methods as followings, thereafter second layer of composite was filled and cured: Group 1 - OIL is allowed to remain on the surface of cured composite; Group 2 - OIL was removed by rubbing with acetone-soaked cotton; Group 3 - formation of the OIL was inhibited using a Mylar strip; Group 4 - OIL was covered with glycerin and light-cured; Group 5 (control) - composite was bulk-filled in a layer. The interfacial shear bond strength between two layers was tested and the fracture modes were observed. To investigate the propagation of polymerization reaction from active area having a photo-initiator to inactive area without the initiator, a flowable composite (Aelite Flow) or an adhesive resin (Adhesive of ScotchBond Multipurpose) was placed over an experimental composite (Exp_Com) which does not include a photoinitiator and light-cured. After sectioning the specimen, the cured thickness of the Exp_Com was measured. The bond strength of group 2, 3 and 4 did not show statistically significant difference with group 1. Groups 3 and 4 were not statistically significant different with control group 5. The cured thicknesses of Exp_Com under the flowable resin and adhesive resin were 20.95 (0.90) urn and 42.13 (2.09), respectively.

• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.293-301
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• 2013

This study discusses the feasibility of coffee bean residue as a raw material of medium-density fiberboard (MDF). In this relation, the effect of coffee bean residue known as an absorbent material on the physical and mechanical properties of MDF manufactured at its different addition level. Coffee bean residue which is a by-product of coffee mill and large amount of waste left over after processing for instant coffee was added at the level of 3, 6, and 9% on dry basis and urea formaldehyde resin was used as the adhesive. The MDF made with mixture of wood fiber and coffee bean residue was tested for physical and mechanical properties as well as formaldehyde emission. The bending strength and internal bonding strength of the MDF made with mixture of wood fiber-coffee bean residue were higher than that of the KS standard in randomized mat structure type, but not in layered mat structure type. Also, the physical properties of MDF made with mixture of wood fiber-coffee bean residue showed a considerable improvement in thickness swelling over the commercial MDF. More importantly, the formaldehyde emission rate of MDF made with mixture of wood fiber-coffee bean residue met the KS standard and was close to that of commercial MDF. These results showed the feasibility of coffee bean residue as a raw material for the production of environmentally-friendly MDF. Additional works on adhesive-coffee bean compatibility, improvement of moisture absorption effect and reduction the formaldehyde emission rate by carbonization of coffee bean residue may be required.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.126-132
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• 2018

As means to increase the use of concrete with recycled coarse aggregate (RCA), this study aims to evaluate the applicability for flexural strengthening of reinforced concrete beam with high-strength concretes and RCA on which FRP plates, used for repair and strengthening of old and low-durability reinforced concrete structures, is applied. In order to increase the adhesive force of epoxy and FRP plate, FRP plate was installed according to Near-Surface-Mounted (NSM) method. 12 specimens were manufactured using substitution rate of RCA (30%), concrete strengths (40MPa, 60MPa), diameters of deformed bar (D10, D13), and types of FRP plate (AFRP, CFRP) as variables to analyse flexural performance according to FRP plate and substitution rate of recycled aggregate. As a result, in all specimens, specimens strengthened by FRP plate showed a maximum of 17% increase in performance compared to specimens without FRP plate and strengthening performance of CFRP was found to be higher than AFRP. When modulus of rupture was used, the value of cracking moment was similar to that of the reference equation. As bending moment of some specimens strengthened by FRP plate failed to satisfy the criteria of KCI 2012 and ACI 440-2R, additional experiment is deemed as necessary.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.335-341
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• 2018

With the improvement of medical state, patients' expectations for the most advanced medical equipment are increasing. Particularly, Magnetic Resonance Image (MRI) is used as one of the core image diagnosis methods in all clinical area. However, it has been reported that many of patients who go through the examination suffer from anxiety to the severe noise level during the examination. In this study, both the noise reduction evaluation of headsets with sound-blocking materials added to existing sound-absorbing materials and the existence of sound blocking materials as artifacts on the examination image are tested. An MRI test noise is recorded as a speaker by cross-ordination the sound material (sponge) and the sound material (acrylic plate, copper plate, and 3D copper plate) inside the headset made from 3D pring. A quantitative assessment of headsets showed that the average headset value was 81.8 dB. The average dB value of the most soundproof material combination(Copper, acrylic plate, sponge, sponge) headsets on headsets with added charactering material was measured at 70.4 dB, and MRI showed that the copper was diamagnetic substance and excluded. The second most soundproof headset(Sponge, acrylic plate, 3D copper plate, sponge) was measured at 70.6 dB and MRI showed no artifacts. The same simulation of the material printed with a 3D copper PLA containing approximately 40 % copper powder resulted in no artifacts, therefore, the material output as a 3D printing was better suited for use. For MRI related research, the mutual development of 3D printing is highly anticipated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.672-681
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• 2018

This study was conducted to test the validity and reliability of the Korean version of the Professional Quality of Life Scale-Short Form (ProQOL-K-SF). Survey data were collected from 191 staff involved in long-term care insurance who worked for National Health Insurance Services. Construct validity using exploratory factor analysis and the internal consistency reliability were determined using SPSS/WIN (21.0). Factor analysis of the ProQOL-K-SF demonstrated that it has a two-factor structure (compassion satisfaction and compassion fatigues) and 13 items that support construct validity. Factor loadings of the compassion satisfaction ranged from 0.70-0.86, factor loading of the compassion fatigues ranged from 0.71-0.82 and the total variance was 60%. The ProQOL-K showed interanal consistency based on Cronbach's ${\alpha}$, with a total scale and two sub scale values of 0.76-0.90. Compassion fatigue and compassion satisfaction of 30 items of the ProQOL-K were positively correlated with those of 13 items of the ProQOL-K-SF. The results support that the ProQOL-K has satisfactory construct validity and is a reliable measure of professional quality of life in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3559-3566
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• 2009

Heating and cooling plate are separately used for heating and cooling cast dies for footwear parts. However, this has a disadvantage that it takes a long time to manufacture footwear parts etc.. In the present study, the pipe-inserted cast die for press forming process was proposed to substitute heating and cooling plate. The temperature distribution on the pipe-inserted cast die was analyzed by numerical work using a FEM. And its temperature was measured by LabView. A manufacturing by the pipe-inserted cast die for press forming process was effectively verified, especially in a productivity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.591-597
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• 2003

In this paper, a compact and broadband PIFA(Planar Inverted F Antenna) which has an additive short-circuit plate along the patch length was designed. For more compact PIFA short-circuit Plate along the patch width is reduced and an additive short-circuit plate along the patch length is used to broaden the bandwidth. The effect of an additive-short-circuit plate along the patch length was verified in single band PIFA and also verified in dual-band PIFA. The commercial software, IE3D, was used to design a PIFA and its performance was verified by comparing simulated results with measurement results.