• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.643-650
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• 2020

The phased array antenna has an advantage enabling rapid beam aim without the mechanical rotation of the antenna, because it arranges multiple elements in a linear or planer (grid or circular) and electronically controls the phase for each element. The planar array antenna is generally used a grid array and a circular array, and the circular form has the higher resolution comparing to the grid form due to the its structural characteristics. However, a concentric circular array (CCA) or a concentric ring array (CRA) with multiple circular arrays which each has different radius is used in the limited area, because the entire radius should be increased for the circular array with a number of elements. In this paper, we introduce the angle-of-arrival (AOA) estimator for an adaptive beamforming satellite system based on CRA and provide the simulation results for performance evaluation. In addition, simulation results are compared and analyzed to the case for the circular array antenna.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.05a
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• pp.80-80
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• 2002

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.4
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• pp.157-162
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• 1987

The basic experiments on the plastic sea eel pots used in fishing were carried out in order to investigate the elasticity of the funnel ribs, hydrodynamic resistance, sinking time and diffusion of the bait from June to October, 1987. The elasticity of the bamboo funnel ribs was higher than that of the polypropylene ribs up to the load 150g. The hydrodynamic resistance R (kg) of the pots towing to the head direction horizontally in relation to towing velocity V (m/sec) was expressed as following formula; R=0.36V super(2.01) and coefficient of drag C sub(D) was 0.52. The sinking times of the covered pots by tape fully or partially were late 1-2 second than the typical pots within the water depth 7.5m. The diffusion tendency through the covered pots using dye and sardine extracts solution was concentrated to the entrance more than the typical pots. However, fishing efficiency as number and weight of fish per pots for nine times fishing operation was revealed no difference between the covered pots and the typical pots.

• Sim-seong Yeon-gu
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• v.30 no.2
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• pp.111-144
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• 2015

Chilseongpul-i is a Korean shamanic myth in which the life story full of hardships of seven sons is told, until they will take up the sacredness of Chilseong god. The seven sons, who were born from Chilseongnim and his wife Okneobuin, are abandoned by their father, Chilseongnim. But sometime later they are born with new characters after going through a special growth process of suffering, dying, and rebirth. They finally recover the sacred position to save their mother. As considered by the analytical psychology, the fact that the seven sons became Chilseong gods shows an individuation process of the heroic mythology. The individuation process might be regarded as a symbol of Self-archetype of Koreans. Self-archetype functions as a healing which gets one's split heart and mind together. An imago dei of healers should be projected upon the seven gods by ancestors.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.242-251
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• 2011

The effects of top and bottom lids on the natural convection heat transfer phenomena inside vertical cylinders were investigated experimentally for $Ra_{Lw}$ from $9.26{\times}10^9$ to $7.74{\times}10^{12}$. Using the concept of analogy between heat and mass transfer, a cupric acid-copper sulfate electroplating system was employed as mass transfer experiments replacing heat transfer experiments. The natural convection heat transfer of both-open cylinders in laminar and turbulent flows was in good agreement with the existing heat transfer correlations developed for vertical plates. The effects of top and bottom lids on the heat transfer rates were very similar to the studies of Krysa et al. and Sedahmed et al. and Chung et al. With the copper lids, the bottom-closed cavity showed the highest heat transfer rates and then followed both-closed, top-closed, both-open ones in both laminar and turbulent flows. However with the acryl lids, the similar trends were observed except that the heat transfer rates for both-open were higher than top-closed one. The use of the copper lids increased the heat transfer rates compared to the acryl lids due to the hydrodynamic interaction of the flows developed for the different heated faces. This study extended the ranges of flow conditions of the existing literatures and proposed the empirical correlations.

• Korean Journal of Plant Resources
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• v.13 no.3
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• pp.179-187
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• 2000

The achene morphology about 16 taxa of Korean Aster L. sensu lato were investigated to estimate its taxonomic values. The achene shapes were divided into four types; oblanceolate-oblong, obovate, oblong and obovate-oblong. The trichome shape on achene six types; uniseriate-conical, filiform, cylindrical, capitate type, long stalk capitate and globular. Their distributional features on upper part of achene four types; absent, sparse distribution of conical trichome, dense distribution of conical trichome and mixed distribution of conical and capitate trichome. The achene shapes and trichome characteristics were regarded to be a good characters in delimiting taxa because these did not differ among individuals in same taxa, but differ among the taxa. If Korean Aster L. sensu late were divided into Kalimeris, Heteropappus, Aster, Cymnaster, the capitate forms and mixed distribution of conical and capitate trichome were recognized as the good characters in delimting above section such as genus Kalimeris and Heteropappus, section Pseudocalimeris of Aster L. sensu stricto.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.49-50
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• 2014

In this paper, a wideband loop antenna for UWB applications is studied. The proposed wideband loop antenna consists of a circular loop and circular sectors. Circular sectors with a ultra-wideband characteristic are used to connect the circular loop and the center feed points. Optimal design parameters are obtained by analyzing the effects of the gap between the circular sectors and the radius of the circular loop on the input reflection coefficient and gain characteristics. The optimized wideband loop antenna is fabricated on an FR4 substrate with a dimension of $41mm{\times}41mm$. Experimental results show that the antenna has a desired UWB characteristic with a frequency band of 3.1-11.0 GHz for a VSWR < 2.25.

• Journal of IKEEE
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• v.21 no.4
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• pp.412-415
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• 2017

In this paper, we propose a multi license plate recognition system using high resolution $360^{\circ}$ omnidirectional IP camera. The proposed system consists of a planar division part of $360^{\circ}$ circular image and a multi license plate recognition part. The planar division part of the $360^{\circ}$ circular image are divided into a planar image with enhanced image quality through processes such as circular image acquisition, circular image segmentation, conversion to plane image, pixel correction using color interpolation, color correction and edge correction in a high resolution $360^{\circ}$ omnidirectional IP Camera. Multi license plate recognition part is through the multi-plate extraction candidate region, a multi-plate candidate area normalized and restore, multiple license plate number, character recognition using a neural network in the process of recognizing a multi-planar imaging plates. In order to evaluate the multi license plate recognition system using the proposed high resolution $360^{\circ}$ omnidirectional IP camera, we experimented with a specialist in the operation of intelligent parking control system, and 97.8% of high plate recognition rate was confirmed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.426-435
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• 2013

In this paper, we propose the MIMO circular polarization feed network to enhance the communication performances from the previous $2{\times}2$ MIMO channel to $4{\times}4$ channel for Land Mobile Satellite communication system. The only possibility to extend the communication channel is to use the additional satellite because of the limitation of satellite spaces to install additional antennas. For overcoming this problems, we propose the MIMO circular polarization feed network to secure the isolation characteristics without the distant antenna space. The port isolation characteristics and each port impedance matching conditions are numerically verified and we suggest the $4{\times}4$ MIMO channel model of the proposed system and the performances are verified. The fabricated circular polarization patch antennas with the proposed feed network are measured in the reverberation chamber and 7~10 dB of diversity gain and 80 % increasement of channel capacity are obtained.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.347-348
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• 2001

마이크로스트립 안테나가 가지는 가장 큰 단점인 협대역 특성을 개선하기 위해 그 동안 수많은 연 구와 방법들이 제안되었는데 특히 원형편파 안테나는 임피던스 대역폭 외에 축비 대역폭까지도 고려 되어야 하므로 더욱 심화된 협대역의 특성을 가지게 되어 설계에 많은 어려움이 있었다. 일반적으로 원형편파 마이크로스트립 안테나를 설계하는 방법 중 급전 구조면에서는 크게 단일 급전 방식과 하이 브리드 형태의 급전방식이 있다. 단일 급전 방식의 원형편파 안테나는 구조가 간단하고y 제작이 간편 하며, 안테나의 물리적 크기를 줄일 수 있어 배열시 장점이 있으나 구조의 특성상 협대역의 축비 대역 폭을 가지며I 하이브리드 급전 원형편파 안테나는 구조가 복잡하고, 제작이 어려우며, 안테나의 물리적 크기가 커진다는 단점이 있으나 광대역의 축비 대역폭을 가진다. 따라서 원형편파 안테나의 설계시 축 비 대역폭과 안테나의 물리적 크기 간의 trade-off를 고려하여야한다. 최근에는 이를 고려한 단일 급전 을 이용하면서도 개선된 축비특성올 얻을 수 있도록 십자개구 개구를 통해 두 개의 직교 모드를 방사 패치에 급전하는 구조가 제안되기도 하였다. 하지만 이는 일반적인 단일 급전 방식보다 개선된 축비 대역폭을 얻을 수 있었으나 중심주파수에서 2.5%에 불과하였다. 본 논문에서는 단일 급전 십자개구 결합 방식이 가지는 협대역의 축비 대역폭을 개선하기 위해 단 일 급전으로 하이브리드 급전의 효과를 가져올 수 있는 직렬 급전 십자개구 결합 마이크로스트립 안 테나를 제안하였으며, 기존에 발표된 단일 급전 십자개구 결합 안테나와의 축비 대역폭, 이득, 방사패 턴, 그리고 임피던스 대역폭 둥과 비교하여 개선된 특성을 제시하고 제안된 안테나의 타당성을 보였 다. 실제로 2.4GHz의 주파수에서 제안한 직렬 급전 십자개구 결합 단일 마이크로스트립 안테나의 측 정결과 기존에 연구된 안테나보다 약 2배정도 증가된 4.6%의 축비 대역폭, 10%의 임피던스 대역폭 (VSWR<1.5), 그리고 8.2dBi의 최대이득 특성을 확인할 수 있었으며, 이를 바탕으로 시권셜 로테이션 기법올 사용한 $2\times2$ 배열 안테나는 17.5%의 축비 대역폭, 20.8%의 임피던스 대역폭(VSWR<1.5), 그리 고 12.5dBi의 최대이득을 얻을 수 있었다. 이에 해당하는 제안된 단일 안태나와 $2\times2$ 배열 안테나의 구조, 측정된 축비 대역폭 및 이득특성, 그리고 입력 반사손실을 그림 I, 2, 3에 각각 나타내었다.