• Computational Structural Engineering
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• v.8 no.1
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• pp.30-38
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• 1995

이방향 천공 발파공법의 실용성을 입증하여 실시공에 착수하기 위해서는 수치해석을 통하여 사전에 종방향 및 방사방향 천공발파에 따른 지표면에서의 지반진동의 영향을 알아보는 것이 필요하였다. 정확한 현장조건과 발파하중이 주어진 상태에서의 정밀해를 구하기 위해서는 시공상의 발파패턴대로 전체 발파공을 모형화하는 것이 필요하나 앞서 언급한 바와 같이 해석목적상 기존공법과 신공법의 지반응답의 차이를 비교하는 것이 주목적이였기 때문에 해석조건을 동일하게 가정하고 발파공도 대표적인 방향성을 가지는 1개공만을 선택하여 해석을 수행하였다. 기존 종방향 천공 발파공법과 신공법인 이방향 천공 발파공법의 상대적 비교를 위한 3차원 동적 해석결과, 관심의 대상이 되는 터널 직상부의 경우 기존의 종방향 천공 발파에 비해 이방향 천공발파는 진동이 두드러지게 감소함을 알 수 있었으며 이는 발파공의 방향성에 따라 지반응답이 크게 영향을 받는다는 것을 의미한다. 따라서 터널굴착시 문제시 되는 지상구조물의 위치에 따라 발파공의 위치를 적절히 조절함으로써 문제발생 예상지역의 진동치를 감소시킬 수 있을 것이라 판단된다. 그러나 이러한 잇점은 확대발파전 파이롯트 터널이라는 자유공간이 존재할 때만 가능하므로 이방향 천공 발파공법은 TBM의 효용성을 극대화시킨 것이라 할 수 있다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.379-387
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• 2000

In this paper, to transmit and receive the differently polarized wideband signals simultaneously with a single antenna system, the wideband, dual-frequency and dual-polarized(WDFDP) microstrip array antenna is proposed and designed. This antenna operates simultaneously at 14.25 GHz and 12.50 GHz. To extend to two dimensional array, microstrip feed line and coaxial probe through via-hole are used. The experimental results show that the proposed WDFDP microstrip antenna can be used in the compact portable terminals with a single antenna system and the characteristic of the resonators in this antenna produces a greatly enhanced bandwidth.

• Composites Research
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• v.14 no.2
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• pp.43-49
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• 2001

The characteristics of smart skin for wireless LAN system under compression load are investigated. The smart skin structure is composed of 3 layers of face material and 2 layers of core material. Theoretical formula for determining buckling load is derived by Rayleigh-Ritz method and compared with experimental result. The maximum length of specimen that buckling does not occur is determined by assuming that the compression load is sustained by only face material. In the experiment, if buckling occurs obviously then it follows the theoretical result well. In the process of buckling, the load supporting capability and the antenna property such as radiation pattern and reflection coefficient were examined.

• Journal of the Korea Society of Computer and Information
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• v.28 no.8
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• pp.11-19
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• 2023

In this paper, it is confirmed that the metrics used to evaluate image quality can be applied to low-light images. Due to the nature of low-illumination images, factors related to light create various noise patterns, and the smaller the amount of light, the more severe the noise. Therefore, in situations where it is difficult to obtain a clean image without noise, the quality of a low-illuminance image from which noise has been removed is often judged by the human eye. In this paper, noise in low-illuminance images for which ground truth cannot be obtained is removed using Noise2Noise, and spatial resolution and radial resolution are evaluated using ISO 12233 charts and colorchecker as metrics such as MTF and SNR. It can be shown that the quality of the low-illuminance image, which has been evaluated mainly for qualitative evaluation, can also be evaluated quantitatively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1417-1425
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• 1990

In this paper, when the glass plate of fragile material is subjected to impact load, the fracture pattern and the generation phenomenon of cone crack were theoretically clarified by using the analysis method of impulsive stress in the first paper. The numerical analysis results of strain distribution at a distance of 0.1cm, from the impact loading point to 5cm, were compared with experimental results. The main conclusions obtained are as follows; (1) The generation phenomenon of cone crack at the impact fracture of the glass plate can be analytically confirmed by using the three dimensional dynamic theory of elasticity. And the numerical analysis results of strain distribution using this theory are relatively in close agreement with the crack size obtained from the impact fracture experiment. (2) After the stress wave generated at the impact point propagated to the spherical compressive wave, this stress wave reflected from the back surface and reached again at the surface of the plate to the spherical stress wave. Then the generation of cone crack can be confirmed along the stress wave surface. (3) The plate is the thicker, the more is the generation phenomenon of cone crack at the lower impact velocity range (20m/s-35m/s). Because the fracture generate before the maximum tensile stress acting to the glass plate, cone crack was rarely ever generated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.157-167
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• 2003

In this paper, to reduce the resonant length of patch, microstrip patch antenna of linear polarization which is suppressed at two radiation edges is designed and fabricated at the frequency of 1.575 GHz. The result is like that the resonant length of patch is 45 mm and the length reduction effect is 43.8 % when it is compared with that(80 mm) of plane type. The gain is 4.4 dBd and -3 dB beamwidths are 112$^{\circ}$ and 66$^{\circ}$ in the E-plane and H-plane, respectively. Also, to reduce the size of patch, microstrip patch antennas those are suppressed at four radiating comers are designed and fabricated at the same frequency in the linear and circular polarization, respectively. For linear polarization, at the 1.2 of width/length(W/L) ratio, the patch area is 53 mm $\times$ 63.6 mm and the size reduction effect is 56.1 % when compared with that(80 mm $\times$ 96 mm) of plane type. The gain is 4.3 dBd and the -3 dB beamwidths are 120$^{\circ}$ and 78$^{\circ}$ in the E-plane and H-plane, respectively. For circular polarization, the patch size(54.2 mm $\times$ 61.5 mm) is reduced by 47.2 % than that(76 mm $\times$ 83 mm) of plane type. -3 dB beamwidth of horizontal polarization in the z-x plane and vortical polarization in the y-z plane are 108$^{\circ}$ and 93$^{\circ}$, respectively and this means the increasement in both planes by 52$^{\circ}$ and 27$^{\circ}$ than those of plane type. The maximum gain is 2.5 dBd in the horizontal polarization in the z-x plane. Axial ratio is 1.5 dB at 1.575 GHz and the 2 dB axial ratio bandwidth(ARBW) is 20 MHz(1.3 %).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.3
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• pp.31-37
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• 2015

In this paper, newly proposed dual-band microstrip antennas using stacked inverted-L-shaped parasitic elements are presented for GPS $L_1(1.575GHz)$ and $L_2(1.227GHz)$ bands. For making dual band which has large interval, ${\lambda}/4$($L_1$ band) inverted-L-shaped parasitic elements were stacked at both side of radiation apertures on the half-wavelength($L_2$ band) patch antennas. The resonance in the parasitic elements occurs through coupling to the patch. Next, due to using circular polarization at GPS, ${\lambda}/4$($L_1$ band) inverted-L-shaped parasitic elements was stacked using sequential rotation technique on the patch and both side of the diagonal corners of the antenna were eliminated to make dual-band circular polarization. The designed circular polarized antenna's dimensions are $0.43{\lambda}L{\times}0.43{\lambda}L{\times}0.06{\lambda}L$ (${\lambda}L$ is the free-space wavelength at 1.227 GHz). Measured -10 dB bandwidths was 120 MHz(7.6%) and 82.5 MHz(6.7%) at GPS $L_1$ and $L_2$ bands. and 3 dB axial ration bandwidths are 172 MHz(10.9%) and 25 MHz(2.03%), respectively. All of these cover the respective required system bandwidths. Within each of the designed bands, broadside radiation patterns were observed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.226-231
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• 2020

Polyvinyl pyrrolidone nanofibers including nickel, zinc, and iron precursors were fabricated via the electrospinning method. To convert as-spun nanofibers to Ni0.5Zn0.5Fe2O4 oxide nanof ibers which is capable of shielding an electromagnetic wave, heat treatment conditions were optimized. To obtain the heat treatment condition that can exclude amorphous carbon black and secondary crystal phase, samples were taken at each temperature while the calcination process and analyzed. According to the X-ray diffraction (XRD) analysis, the Ni0.5Zn0.5Fe2O4 crystal phase started to appear from 300℃, but it was confirmed through energy dispersive spectroscopy (EDS) analysis that heat treatment of 500℃ or more was required to remove most of the carbon black. When the calcination temperature exceeds 650℃, crystal nuclei starts to grow and the fiber surface condition becomes rough, so it was confirmed that the heat treatment conditions should be selectively determined according to the application field.

• Archives of design research
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• v.17 no.1
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• pp.25-36
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• 2004

The purpose of this study is to analyse and interpret the way of differentiated expression and changing creative trend following 5-day workweek which has been recently adopted. For this aim 11 pieces of distinctive advertising text were analysed. The criteria for selection of analysing text were relativeness with 5-day workweek and cognitive inconsistency. These texts were negative phrases, exaggerated expression, and excessively humorous appeals. The study revealed the followings: First, 5-day workweek concerned advertising texts were considered as high attention getting and successful in stimulating advertising audiences' curiosity by using the elements opposing the value and belief system formed in the existing audience. Second, consumption-driving lifestyle was found in most expressions for credit cards advertising. Third, hedonic need-oriented lifestyle was typical in young consumer products category. Fourth, family centered lifestyle emphasized meaning of rest and solidarity of family.

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.208-213
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• 2007

A 15 kg 6-year-old intact male Jindo dog with a history of a respiratory distress, hindlimb paralysis with necrosed skin of dorsal digit for three weeks was referred to Animal Medical Center, Chonbuk National University. Heartworm infection was identified by kit examination. In plain thoracic radiographs, dilated pulmonary arteries reverse D sign and focal interstitial pattern was compatible with heartworm infection and possible pulmonary thromboembolism. Abdominal radiographs showed poor serosal detail indicating fluid accumulation within peritoneal cavity. No evidence of musculoskeletal abnormalities was found. Ultrasonography presented focal wedge-shaped hyperechogenecity on the both poles of left kidney, weak or absent pulse on the distal to the external iliac artery as well as ascites and irregular liver margin. Multi-organ failure was strongly supposed by blood profile including leukocytosis, anemia, hemoglobinuria bililubinemia, hypoalbuminemia, imbalance of electrolytes, and increased hepatic and renal function values. Interestingly, the glucose level is remarkably lower in pelvic limb compared to thoracic limb. Suspected pulmonary thromboembolism, renal infarction and femoral arterial embolization causing hindlimb paralysis and dermatic necrosis were confirmed by 3D reconstructed CT imaging. Prior to taking a consideration of euthanasia, interventional radiology was experimentally attempted but failed due to not recovered from general anesthesia. Early and accurate diagnosis of thromboembolism is valuable and 3D reconstructed CT images might be very useful to show the correct way to treat effectively.