• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.306-310
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• 2002

본 논문에서는 기존의 혼 안테나에 Dielectric rod를 삽입하는 구조를 사용하였다. 입력구조는 Rectangular Waveguide Feed에 Cone을 접목시키는 형태로 구현되었으며 기존의 E-Plane taper구조보다 특성이 양호하며 소형화를 구현해냈다. 제작된 안테나의 중심주파수는 37GHz이며 정재파비 특성 또한 양호하다. 여러 Feeding 구조 중 Bandwidth를 좀더 확장할 수 있는 구조에 초점을 맞추어 대역폭은 13%이상을 구현했으며 시뮬레이션 툴은 Ansoft HFSS V7.0으로 최적화한 후 제작 및 측정하였다. 또한 사용된 Dielectric rod의 제질은 Teflon(ETFE, $\varepsilon$$_{r}$=2.03)을 사용하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1203-1214
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• 1989

본 연구에서는 화이버각도, 경계조건 및 하중형태의 변화에 따라 적층 복합재료원통 셸 구조물의 수치예를 제시하고, NASTRAN수치결과 및 기존 문헌들과 비교하여 구하여진 결과의 타당성을 입증하였다.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.434-439
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• 1996

To investigate influence of the incident beams which have the truncated Gaussian amplitude and of the shapes of bump on read-out signal is an optical disc, and the point spread function on bump, the scalar diffraction theory is used in this paper. We consider the truncated Gaussian amplitudes which are $\sigma$=0, 0.5, 1.5, and 2.5, the height of bump which is given by $n{\Delta}_0={\lambda}/4$, and the phase height of bump which is then given by ${\Phi}_0={\pi}$. We also consider the shapes of the bump which are a rectangular shape, a frustoconical shape, and a conical shape. It is shown that as the truncation of incident beam reduces the radius of central spot on bump decreases, the maximum value of read-out signal increases, and that the size of bump decreases. From these results, we get better read-out signal and the reduced cross-talk in optical disc when the truncation of incident beam reduces. Therefore a laser beam having less truncated Gaussian amplitude may useful for an actual optical disc.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.343-343
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• 2001

최근 전자산업과 전파통신산업의 발달에 따라 불요전자파에 의한 전자파장해가 심각한 수 준에 이르게 되었다. 그 결과 국 . 내외 전자파환경은 나날이 악화되고 있으며, 이로 인한 사 회적 문제가 점차 증가되고 있는 실정이다. 이에 대한 대책으로 CISPR(Comite Internationale S Special des Perturbations Radioelectrique), FCC (Federal Communications Commissions) A ANSI(Amercian National Standards Institute) 둥이 주축이 되어 국제 규정이 제정되어 각종 전자기기들에 대해 방사(EMI) 및 내성(EMS)의 규제가 강화되고 있다. 그러나 국제규정이 요구하는(30 MHz - 18 GHz) 주파수 범위에서의 EMIjEMS 측정을 하기 위해 광대역(Broad-band) 전파무향실(Anechoic Chamber)이 필요하지만1 기존의 Ferrite T Tile 또는 그리드형 전파홉수체는 20 dB 이상 전파를 홉수할 수 잇는 주파수 대역이 30 M MHz - 400 MHz 또는 780 MHz에 불과하기 때문에 상기의 조건을 만족하는 전파무향실 을 구성하기에는 곤란한 실정이다. 본 논문에서는 국제 규격을 만족하는 전파무향실을 위한 광대역 전파홉수체를 개발하기 위해, 다충형으로 구성하고, 전파흡수체의 형상을 변화시켜 등가재료정수법을 사용하여 설계하고 그 특성을 평가함을 그 목적으로 하였다. 따라서 본 논문에서는 본 연구실에서 기폰에 제안한바 있는, 금속판 위에 타일형 페라이 트 충, 그 위에 원추절단형 페라이트 층과 원통형 페라이트 층을 적층시칸 형상의 전파홉수 체는 30 MHz - 6 GHz 정도까지 커버할 수 있으나, 1 GHz 부근의 주파수 대에서 16 dB 정도의 홉수능 밖에 가지지 못하였다. 이를 개선하기 위해, 금속판 위에 타일형 페라이트 층 을 형성하고 그 위에 원통형 페라이트 충, 원추절단형 페라이트 충I 원통형 페라이트 충, 타 원형 페라이트 충을 형성한 새로운 형태의 전파홉수체를 제안하였다. 본 논문에 제안한 새로운 형태의 전파흡수체의 시물레이션 결과 30 MHz - 20 GHz의 주파수 범위에서 전반적으로 25 dB이상의 전파흡수능을 가짐을 확인하였으며/ 특히 기폰에 제안한 전파홉수체와 비교하면,1GHz 부끈에서의 전파홉수능을 10 dB 이상 개선하였다. 나아가서/ 실재로 제작한 전파흡수체의 측정된 주파수특성이 시율레이션에 의한 이론치와 3 30 MHz - 6 GHz의 범위에서 잘 일치함을 확인하였다. 또한y 전파 홉수체의 전체 높이는 2 27 mm 밖에 되지 않으므로 본 연구에서 제안한 전파 홉수체를 사용할 경우 전파무향실의 유 효공간 확보에 매우 유리한 이점을 가진다

• Korean Journal of Plant Resources
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• v.12 no.1
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• pp.50-61
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• 1999

The leaf morphological and anatomical characters about 17 taxa of Aster and its allied taxa were investigated to estimate taxonomic values. Leaf shapes of the treated taxa were divided into five types; elliptic, spathulate, lanceolate, linear, ovatodeltoid. These types were fixed in same taxa, but variable among different taxa, therefore useful as taxonomic character. Leaf margins were divided into four types; entire, serrate, dentate, incised, these types were invariable in most taxa, but variable among individual in same taxa such as Kalimeris incise, Aster spathulifolius. The size and shape of leaf epidermal cell, the size and distributional numbers per 10$\textrm{mm}^2$ of stomata, deposit feature of cuticle were not distinguished clearly from treated taxa, but presence of stomata on adaxial surface, size and distributional numbers per 10$\textrm{mm}^2$ of stomata were useful taxonomic characters in some taxa such as Gymnaster koraiensis, Aster altaicus var. uchiyamae, Aster tripolium, Heteropappus arenarius. The leaf trichomes were divided into five types by basic form, sculpturing on their outer surface and cell arrangement; uniseriate granulate conical type, uniseriate psilate conical type, uniseriate psilate filiform type, globular type, biseriate vesicular capitate type. In spite of various habitat, basic morphology of trichomes were not changed, therefore, it was thought to be good taxonomic character.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.288-300
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• 1997

Morphology and anatomy of the fruit and seed of eight species of Rhus (Anacardiaceae) were investigated. The inflorescence of R. typhina was an apical and erect thysus, that of R. javanica was panicle. while that of the others were an axillary and pendulous panicle. Anatomical investigation of the pericarp showed that exocarp and mesocarp in R. javanica and R. typhina were integrated, but its in the others were disintegrated and uniform. In all these species, endocarp consisted of distinctly three lignified cell layers (outer, middle and inner endocarp) and crystal layers. The surface sculpturing of mature seed was variable and also contributed to understanding of species delimitation and relationships within the genus. Categorization by cluster analysis with 27 characters obtained from morphological and anatomical features of the fruit and seed resulted in two groups : R. trichocarpa - R. javanica group vs. R. ambigua - R. verniciflua - R. sylvestris - R. succedanea group. Taxonomic significance for the genus by these characters was supported by results of principal component analysis. The keys for the genus Rhus were provided using morphological and anatomical characters of the inflorescence, and fruit and seed.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.488-496
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• 2010

Dens evaginatus is a tooth with cylindrical enamel projection which forms a nodule on occlusal surface. It could be explained as outward overgrowth of inner enamel epithelium or localized hyperplasia of pulpal mesenchymal tissue during tooth development. A problem is that it is likely to be worn out or fractured by mastication ensuing pulpal inflammation. It is occasionally found on the lingual surface of upper anterior teeth as well, called talon cusp. Dens invaginatus is a tooth with deep lingual pit made by invagination of lingual enamel epithelium during tooth development while it is considered normal in terms of size and shape. Radiographically, a part of cervical enamel shows inward growth forming cavity and it is reasonable to say that the base is possibly open to pulpal cavity since they are very close. Talon cusp and dens invaginatus are relatively common abnormality of shape. However it becomes the opposite if the two exist in the same tooth. Once the talon cusp is broken by occlusal force or fissure between cusps is decayed, the complicated structure of canals makes the pulpal treatment difficult. Preventive treatments such as occlusal equilibrium and sealant, and regular oral examination should be preceded and thorough understanding of canal shape, using radiography, is required when pulpal treatment is necessary. This report is about a 9- year-old boy(lower left central incisor), a 8-year-old girl(upper right central incisor), and a 7-year-old boy(upper right central incisor), who have dens invaginatus and talon cusp in the same teeth. The first and the second patients are under pulpal treatments, and the last one is being observed showing no pathologic impressions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.1
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• pp.36-43
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• 1978

Ears collected from 500 regions were phenotypically observed for their ear and kernel characters. Characters studied included ear shape, kernel color, kernel density, ear row number, starch quality, pop corn and waxy corn, ear length, ear diameter, kernel length, kernel width, kernel weight, ear weight, and 100 kernel weight. The Korean local corn collected were mostly flint type and were very diverse in all the characters studied. The collected local corn would be very promising for providing good germplasm for corn breeding in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.413-420
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• 2009

We propose a novel feed network for a $2{\times}2$ array antenna to form a sectoral conical beam. The proposed feed network, which is a symmetrical structure, consists of four $90^{\circ}$ hybrids, a crossover, and four $90^{\circ}$ delay lines. To verify the performance of the feed network a $2{\times}2$ array antenna and the feed network are fabricated on a microstrip structure, and the radiation patterns are measured at the center frequency of 2.57 GHz. The maximum radiation is measured at the $45^{\circ}$ elevation angle and at the $45^{\circ}$, $135^{\circ}$, $225^{\circ}$, and $315^{\circ}$ azimuth angles depending on the choice of the input port of the feed network.

• Korean Journal of Plant Taxonomy
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• v.43 no.1
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• pp.56-62
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• 2013

Echinochloa oryzoides (Ard.) Fritsch (Na-do-non-pee), was found at paddy fields of Jeonranamdo on a large scale after a first discovery at Masan, Kyeongsangnamdo. This species was not easily distinguished from rice before flowering at the paddy field because of a similar morphology to rice. It is, however, distinguished from other species of the Korean Echinochloa by reliable morphological characters such as horizontal or drooping panicles at maturity, lower glumes with usually 1/4-2/5 as long as the spikelets, awned lower lemmas, and the number of chromosomes, 2n = 54. Echinochloa oryzicola (Vasinger) Vasinger was distinguished from E. oryzoides by erect panicles, lower glumes with at least 1/2 as long as the spikelets, and the number of chromosomes, 2n = 36.