• Journal of Information Technology Services
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• v.12 no.3
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• pp.323-330
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• 2013

In this paper, miniaturized patch antenna operating at ISM band has been designed by applying the fractal technique. Various type of antenna structure, microstrip patch antenna and koch curve microstrip patch antenna has been proposed and simulated using Ansoft HFSS (High Frequency Structure Simulator). The area of microstrip patch antenna and koch microstrip patch antenna is 1,058 $mm^2$, and 891 $mm^2$ respectively, showing the size reduction ratio of 16%. The finally made koch curve microstrip patch antenna resonates at 2.45GHz with return loss of 22.69dB, VSWR of 1.2142, and antenna radiation gain of 3.26dBi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2823-2830
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• 2014

The antenna miniaturization technique involves the increment of the electrical length of the resonator the variation of the physical appearance of the antenna. The most typical method of size reduction is designing helical antenna, meander antenna, and fractal antenna. Size reduction using fractal antenna is proposed in this paper. Fractal koch curve has been etched in microstrip patch antenna to downsize the antenna at ISM (Industrial Scientific and Medical) frequency band of 2.45 GHz koch curve microstrip patch antenna ha FR4 epoxy substrate with dielectric constant 4.7, loss tangent equal to 0.02 and dielectric high of 1.6 mm. The designed antenna is fabricated using etching process. The fabricated antenna has return loss of 2.45 GHz, VSWR of 1.1492, and impedance is matched to $46{\Omega}$.

• Communications of the Korean Mathematical Society
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• v.28 no.1
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• pp.155-162
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• 2013

Although the snowflake curve, the boundary of the Koch snowflake, is one of the well-known fractals, there is no iterated function system (IFS) for it in the literature. In this study, we give an IFS for this familiar closed curve.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.1005-1012
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• 2010

In this paper, a novel log periodic cantor koch dipole antenna(LPCKDA), which is composed of the cantor Koch dipole elements instead of the Koch dipole elements, is proposed to reduce the size of the log periodic koch dipole antenna(LPKDA). To investigate the reliability of the proposed antenna, the LPCKDA is designed and analyzed at 0.5~1.5 GHz and compared with the LPKDA(Log Periodic Koch Dipole Antenna) characteristic. It is shown that although the proposed LPCKDA has a decreases of 5 % in the length of the dipole elements, radiation characteristics of LPCKDA are similar to radiation characteristics of the LPKDA.

• Bulletin of the Korean Space Science Society
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• 2001.04a
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• pp.21-21
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• 2001

No Abstract, See Full Text

• The Mathematical Education
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• v.37 no.1
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• pp.115-138
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• 1998

We seek the possibility of introduction of Fractals to the high school math. curriculum through identifying Fractals teaching programs appropriate for the scopes and sequences in math. education for the high school students. We presented the contents of Fractal theory suitable for the high school students. The following subjects were chosen to be introduced; self-similarity, Fractal dimension, Cantor set, Sierpinsky triangle, Sierpinsky carpel Koch curve, Koch island, perimeter estimate of rugged profiles drawn on paper, and chaos game. We developed the working papers and the criteria for appraisal. Each working paper focuses on the activities in which students can solve the given problems, understanding the characteristics and ideas of Fractals. The working papers were given to the second year students who take science course, and the degree of achievements were analyzed based on the appraisal criteria. The results show that it is possible to introduce Fractals to the high school students.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1242-1246
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• 2007

In this study, FSS(Frequency Selective Surface) with Koch Fractal Curve slot is positioned on the conventional single layer microstrip patch antenna. Numerical results of the proposed antenna bandwidth and the antenna gain are increased compared with those of the conventional single layer microstrip patch antenna. In the future, the fractal geometry of the slot in FSS(Frequency Selective Surface) as a supplementary microstrip patch is researched for the enhancement of the microstrip patch antenna characteristics.

• Korean journal of applied entomology
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• v.13 no.1 s.18
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• pp.25-31
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• 1974

This survey was aimed to accumulate basic data of aphid population at the Horticultural Experiment Station at Suweon. The yellow pan traps were setted at five locations (Fig.1.), and ran from May 1 to October 31. 1970. About one hundred and twenty species of aphids were trapped, including 24 species of plant vims vectors. Of these, dominant species were as follows: (Asterisk shows virus vector) Aphid species No. of catches * Aphis spiraecola PATCH 2,635, * Aphis craccivora KOCH 2,377, * Myzus persicae SULXER 2,111, Capitophorus hippophaes javanicus H.R. LAMBERS 2,051, Anoecia fulviabdominalis SASAKI 1,480, * Aphis gossypii GLOVER 867, * Macrosiphum avenae FABRICIUS 859, Cervaphis quercus TAKAHASHI 692, * Lipaphis erysimi KALTENBACH 645, Pleotrichophorus chrysanthemi THEOBALD 489, The above 10 species consisted $76.5\%$ of total catches and the 24 vector species consisted $55.5\%$. The curve of the seasonal occurrence of flying aphids at Horticultural Experiment Station shows bimodal, typical for the temperate region. The total number of trapped aphids at the Station from May to September, 1970, were less than that of average yearly catches at the College of Agriculture from 1967 to 1970. Thi, low numbers at Horticultural Experiment Station may attribute to the frequent spraying of insecticides from Spring to Summer on growing crops there. But the aphids population increase suddenly in the middle of October. This might be resulted from cease of insecticide applications and migration of aphids from summer host to winter host plants.