• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.3
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• pp.50-56
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• 2010

In this paper, compact broad-band antenna using circular spiral slot and CPW (coplanar waveguide) feed is proposed. The proposed antenna is designed on the same plane of the substrate by using CPW fed structure, archimediean spiral slot structure. So it was achieved both the size of compact antenna and the broad band. A archimediean spiral slot structure is introduced for resonance of medium band operation. The distances of a CPW feeder line and a ground plane are modified for impedance matching and lower/higher band operation. The proposed antenna has a compact size ($8mm\;{\times}\;13mm$) and it is etched on the FR-4 (relative dielectric constant 4.4, thickness 0.8mm) dielectric substrate. The simulated impedance bandwidth (VSWR $\leq$ 2) and maximum gain of the proposed antenna are 5.98GHz (4.1GHz ~ 10.08GHz) and 3.97dBi, respectively. The measured impedance bandwidth (VSWR $\leq$ 2) and maximum gain of the proposed antenna are 6.02GHz (4.48GHz ~ 10.5GHz) and 2.68dBi, respectively. The simulation and measured result shows good impedance matching and radiation pattern over the interesting frequency bands. It can be applied to antenna of broad-band wireless communication system.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.15 no.1
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• pp.31-36
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• 2004

Background and Objectives : It has been shown that the epilaryngeal tube in the human airway is responsible for vocal ring, or the singer's formant. In previous study, authors showed that in trained tenors, besides the conventional singer's formant in the region of ,5500Hz, another energy peak was observed in the region of 8,000Hz. This peak was interpreted as the second resonance of the epilarynx tube. Singers in other voice categories who produce vocal ring are assumed to have the same peak, but no measurements have as yet been made. Materials and Methods : Fifteen tenors, fourteen baritones, seven sopranos and five mezzo sopranos attending the music college, department of vocal music who could reliably produce the head and chest registers were chosen for this study. Each subject was asked to produce an/ah/sound for at least three seconds for the head register sound(tenors ; G4, barions ; E4 sopranos ; F5 and mezzosopranos ; C5) and for the chest register sound (tenors ; C3, baritones ; D3, sopranos ; D4 and Mezzosoprano ; A3). The sound data was analyzed using the Fast Fourier Transform (FFT)-based power spectrum, Long term average(LTA) power spectrum using the FFT algorithm of the Computerized Speech Lab (CSL, Kay elemetrics, Model 4300B, USA). Statistical analysis was performed using the Mann-Whitney test of the Statistical Package for Social sciences(SPSS). Results : For head register sounds, a significant increase was seen in the 2,200-3,400Hz region(p<0.05) and the Similar to the head register sounds, there was a significant increase in energy in the four trained singer group compared with the untrained group in the 2,200-3,100Hz region(p<0.05), the 7,800-8,400Hz region(p<0.05) for the chest register sounds. Conclusions : When good vocal production was made for the head and chest registers, an energy peak was observed near 2,500Hz, a frequency already known as the "singer's formant', in all subjects in the study group. Another region of increased energy was observed around 8,000Hz that had not been noticed previously. The authors believe this region to be the second singer's formant.

• Journal of the Korean earth science society
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• v.36 no.7
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• pp.632-642
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• 2015

Seismograms are composed of 3 characteristics, that is, seismic source, attenuation, and site amplification. Among them, site amplification characteristics should be considered significantly to estimate seismic source and attenuation characteristics with more confidence. This purpose of this study is to estimate the site amplification characteristics at each site using horizontal to vertical (H/V) spectral ratio method. This method, originally proposed by Nakamura (1989), has been applied to study the surface waves in microtremor records. It has been recently extended to the shear wave energy of strong motion and applied to the study of site amplification. This study analyzed the H/V spectral ratio of 6 ground motions respectively using observed data from 4 sites nearby in Yedang Reservoir. And then, site amplification effects at each site, from 3 kinds of seismic energies, that is, S waves, Coda waves energy, and background noise were compared each other. The results suggested that 4 sites showed its own characteristics of site amplification property in specific resonance frequency ranges (YDS: ~11 Hz, YDU: ~4 Hz, YDD: ~7 Hz). Comparison of this study to other studies using different analysis method can give us much more information about dynamic amplification of domestic sites characteristics and site classification.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.378-386
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• 2018

The present paper suggests the original form of the bell pavilion for the King Song-Dok bell which is one of the precious national treasure of Korea. In order to this, many literatures were reviewed including both historical and acoustical references. As the results, the model of the bell pavilion for the King Song-Dok bell is suggested as follows considering acoustical characteristics of the King Song-Dok bell and the traditional Korean bells ; 1) The bell pavilion has the rumbling puddle beneath the bell on the ground floor for resonance of sound 2) Many lumbers are used for columns and beams rather than boards since natural frequencies of the bell are 64 Hz and 168 Hz so that the sound absorption of the low frequency sound may not be occurred. 3) Only some boards may be used for the area between upper and middle molding of lintel in order to prevent of direct sunlight and sea breeze since this type of structure were used for bell pavilion of the same age. 4) Square form with the odd number of 3 or 5 Kans is adopted for bell pavilion considering the weight and the size of the bell which had been used traditionally 5) Finally, half-hipped structure is used for the roof of the bell pavilion which was the predominant form of the age.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2223-2231
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• 2015

In this paper, we propose a built-in antenna for wireless USB dongle which has a modified structure from the existing planar monopole antenna. The proposed antenna implemented a dual-band characteristic by inserting Strip1, Strip2, Strip3 into the monopole structure combined with 'n' shape and feeded 50-Ω using coaxial cable. The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.6, and its overall size is 10 mm × 50 mm × 1mm. Based on the measurement results of the return loss, it was confirmed to satisfy the dual band resonance characteristics of 740 MHz (2.3 ~ 2.7 GHz) and 1,200 MHz (5.15 ~ 5.825 GHz) by -10 dB. In addition, we obtain the omni-directional radiation pattern measurements in the operating frequency bands, and the maximum gain of the proposed antenna has 2.26~3.81 dBi in the 2.4 GHz band and 2.21~5.79 dBi. in the 5.5 GHz band, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.38-42
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• 2005

B$_2$O$_3$ added Ba(Mg$_{1}$3/Nb$_{2}$3/)O$_3$ (BBMN) ceramics were not sintered below 900 $^{\circ}C$. However, when CuO was added to the BBMN ceramic, it was sintered even at 850 $^{\circ}C$. The amount of the $Ba_2$B$_2$O$_{5}$ second phase decreased with the addition of CuO. Therefore, the CuO additive is considered to react with the B$_2$O$_3$ inhibiting the reaction between B$_2$O$_3$ and BaO. Moreover, it is suggested that the solid solution of CuO and B$_2$O$_3$ might be responsible for the decrease of the sintering temperature of the specimens. A dense microstructure without pores was developed with the addition of a small amount of CuO. However, a porous microstructure with large pores was formed when a large amount of CuO was added. The bulk density, the dielectric constant ($\varepsilon$$_{r}$) and the Q-value increased with the addition of CuO but they decreased when a large amount of CuO was added. The variations of those properties are closely related to the variation of the microstructure. The excellent microwave dielectric properties of Qxf = 21500 GHz, $\varepsilon$$_{r}$ = 31 and temperature coefficient of resonance frequency($\tau$$_{f}$) = 21.3 ppm/$^{\circ}C$ were obtained for the Ba(Mg$_{1}$3/Nb$_{2}$3/)O$_3$+2.0 mol%B$_2$O$_3$+10.0 mol%CuO ceramic sintered at 875 $^{\circ}C$ for 2 h.h.2 h.h.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.152-157
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• 2012

Due to the global warming and energy exhaustion, energy efficiency improvement of construction is recognized the stream of times. To improve the efficiency of the building, in order to energy saving, passive elements should be applied. Then the first step be supposed that applying the new standards about the insulation boundary. The current insulation boundary standards are not reasonable as well as does not divide the purposes. As a result, energy is being wasted and many civil complaints are also occurred. To improve these problems, applying the insulation boundary need to divide the heating and non-heating and subdivide the purpose of construction. In this study, accurate real heating and air conditioning areas are presented that work on the new insulation boundary of purposes and applicable standards. This proposed, by the real heating and air conditioning areas, insulation boundary of purposes, matching the reasonable capacity and load of equipment, by working on standards by optimal maintenance can be energy saving, to present guidelines that environment improvement of actual residents as well as energy saving be expected.

• Korean Journal of Materials Research
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• v.9 no.9
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• pp.943-947
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• 1999

The crystal structure and the microwave dielectric properties of $La(Mg_{1/2}Ti_{1/2})O_3$ ceramics have been investigated. $La(Mg_{1/2}Ti_{1/2})O_3$ has the 1:1 ordered monoclinic structure with the lattice parameters of $a = 5.5467(3){\AA}, b = 5.5616(3){\AA}, c = 7.8426(5) {\AA} and \beta = 89.9589 (2)^{\circ}$ The spacegroup of LMT is $P2_1/n$. Monoclinic LMT has the in­phase and anti-phase tilting of octahedra with the $a^_a^_c^_$ tilting system. Anti-parallel shift of A-site cations was also found in LMT. The relative density of the specimens sintered above $1600^{\circ}C$ was ranged between 95 % and 96 % of the theoretical density and the dielectric constant of specimens was about 28. The highest $Q\timesf$ achieved in this investigation was 63,100 for the specimen sintered at $1630^{\circ}C$ for 5 hr. Temperature coefficient of resonance frequency ranged from $>-74 ppm/^{\circ}C ~ -79 ppm/^{\circ}C$.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.3
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• pp.325-332
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• 2006

Statement of problem. Primary implant stability has long been identified as a prerequisite to achieve osseointegration. So the application of a simple, clinically applicable noninvasive test to assess implant stability and osseiointegratation are considered highly desirable. Purpose. The purpose of this study was to evaluate the ISQ value and the insertion torque of the 3 different implant system, then to evaluate whether there was a correlation between ISQ value and insertion torque; and to determine whether implant design has an influence on either insertion torque or ISQ value. Material and method. The experiment was composed of 3 groups: depending on the implant fixture design. Group1 was Branemark type parallel implant in $3.75{\times}7mm$. Group2 was Oneplant type straight implant in $4.3{\times}8.5mm$. Group3 was Oneplant type tapered implant in $4.3{\times}8.5mm$. Depending on the density of the bone, 2 types of bone were used in this experiment. Type I bone represented for cortical bone, type II bone represented for cancellous bone. With the insertion of the implant in type I and type II bone, the insertion torque was measured, then the ISQ value was evaluated, and then the correlation between insertion torque and ISQ value was analyzed Result and conclusion. Within the limitations of this study, the following conclusions were drawn. 1. Within the 3 different implants, the insertion torque value and ISQ value were higher in type I bone, when compared with type II bone.(p<0.05) 2. In type I and type II bone, Oneplant type tapered implant has the highest value in insertion torque.(p<0.05) 3. In type I and type II bone, there was no difference in ISQ values among the 3 types of implant. (p>0.05) 4. Significant linear correlation was found in $Br{\aa}nemark$ type parallel implant: $3.75{\times}7mm$ in type II bone.

• Journal of Periodontal and Implant Science
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• v.38 no.sup2
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• pp.363-372
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• 2008

Purpose: This study compared the effects of coating implants with hydroxyapatite (HA) using an ion beam-assisted deposition (IBAD) method prepared with machined, anodized, sandblasted and large-grit acid etched (SLA) surfaces in minipigs, and verified the excellency of coating method with HA using IBAD. Material and Methods: 4 male Minipigs(Prestige World Genetics, Korea), 18 to 24 months old and weighing approximately 35 to 40 kg, were chosen. All premolars and first molars of the maxilla were carefully extracted on each side. The implants were placed on the right side after an 8 week healing period. The implant stability was assessed by resonance frequency analysis (RFA) at the time of placement. 40 implants were divided into 5 groups; machined, anodized, anodized plus IBAD, SLA, and SLA plus IBAD surface implants. 4 weeks after implantation on the right side, the same surface implants were placed on the left side. After 4 weeks of healing, the minipigs were sacrificed and the implants were analyzed by RFA, histology and histometric. Results: RFA showed a mean implant stability quotient (ISQ) of $75.625{\pm}5.021$, $76.125{\pm}3.739$ ISQ and $77.941{\pm}2.947$ at placement, after 4 weeks healing and after 8 weeks, respectively. Histological analysis of the implants demonstrated newly formed, compact, mature cortical bone with a nearby marrow spaces. HA coating was not separated from the HA coated implant surfaces using IBAD. In particular, the SLA implants coated with HA using IBAD showed better contact osteogenesis. Statistical and histometric analysis showed no significant differences in the bone to implant contact and bone density among 5 tested surfaces. Conclusion: We can conclude that rough surface implants coated with HA by IBAD are more biocompatible, and clinical, histological, and histometric analysis showed no differences when compared with the other established implant surfaces in normal bone.