• 대한전자공학회논문지
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• 제15권6호
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• pp.29-34
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• 1978

아나로그 무선통신계와 디지탈 무선통신계가 각기 동일 무선주파수대의 인접주파수를 사용함에 의한 시스템간 간섭이 존재하는 상태하에서 이들 양 무선통신계가 혼재하기 위해 필요한 최적조건을 구하고자 그의 제일단계로서 아나로그계가 디지탈계에 미치는 시스템간 간섭에 대해 이론적 해석을 행했다. 이에는 특히 이제까지 불분명했던 PSK 신호에 미치는 FM 신호의 간섭영향에 대해서 논했다. 본 연구에서 얻어진 결과는 시스템간 간섭의 존재하에 있어서의 PSK 시스템에 대한 각파수할당 및 대역폭, 전력 등을 정함에 있어 유효한 자료를 제공한다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.179-184
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• 2016

In recent years, the on-resistance, power loss and cell density of Si power devices have not exhibited significant improvements, and performance is approaching the material limits. GaN is considered an attractive material for future high-power applications because of the wide band-gap, large breakdown field, high electron mobility, high switching speed and low on-resistance. Here we report on the Ohmic contact resistance and reverse-bias characteristics of AlGaN/GaN Schottky barrier diodes with and without annealing. Annealing in oxygen at $500^{\circ}C$ resulted in an increase in the breakdown voltage from 641 to 1,172 V for devices with an anode-cathode separation of $20{\mu}m$. However, these annealing conditions also resulted in an increase in the contact resistance of $0.183{\Omega}-mm$, which is attributed to oxidation of the metal contacts. Auger electron spectroscopy revealed diffusion of oxygen and Au into the AlGaN and GaN layers following annealing. The improved reverse-bias characteristics following annealing in oxygen are attributed to passivation of dangling bonds and plasma damage due to interactions between oxygen and GaN/AlGaN. Thermal annealing is therefore useful during the fabrication of high-voltage GaN devices, but the effects on the Ohmic contact resistance should be considered.

• 한국전자파학회논문지
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• 제17권2호
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• pp.152-157
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• 2006

본 논문에서는 새로운 간섭 모델, 실제적인 HAPS(High Altitude Platform Station) 간섭 시나리오, HAPS 시스템과 FWA(Fixed Wireless Access) 시스템에 대한 안테나 패턴, 송신 전력 등과 같은 파라미터들을 이용하여 HAPS 시스템의 지상국(GS: Ground Station)으로부터 P-MP(Point-to-Multipoint) FWA 기지국(BS: Base Station)로의 간섭 및 HAPS 시스템의 GS로부터 FWA 단말국(TS: Terminal Station)으로의 간섭 영향에 대하여 분석하였다. 분석 결과를 보게 되면, HAPS GS로부터 P-MP FWA BS로의 간섭의 경우, 섹터화된 안테나를 사용하는 BS국이 nadir (HAPS 커버리지 중심)의 반대편을 바라보고 있을 때에 두 시스템은 효율적으로 운용될 수가 있다. 그러나 HAPS GS로부터 P-MP FWA TS로의 간섭의 경우에서는 충분한 이격거리가 보장되지 않거나, 간섭 경감 기법을 사용하지 않는다면 이 대역에서 두 시스템은 효율적인 스펙트럼 공유가 불가능하다.

• 복식
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• 제52권5호
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• pp.61-77
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• 2002

The purpose of this study is to investigate difference and likeness on the form in women's Hanbok between the later Chosun Dynasty and modern times based on Belong's observing system for 'Apparel-Body Construct'. Belong's framework is composed 5 pairs of contrast word -'Closed or Open', 'Whole or Par', 'Planar Separation or Planar integration'. 'Flat or Rounded', and 'Determinate or Indeterminate'. Major findings of this study are as follows. First, the form of women's Hanbok in later Chosun Dynasty is 'Variably Closed', 'Part' and 'Rounded', whereas that in modern is 'Open', 'Whole' and 'Flat' Women's Hanbok of modern is lesser convex, and more open than that of later Chosun Dynasty according to increasing use of transparent textiles. Moreover, in comparison with old style, that of modern has the tendency of perceiving primarily whole feature by organic linkage of parts. Because of loose fit of Jeogori and rigid DongJong etc, characteristic of 'Plat' strengthened in modern Hanbok. Secondly, women's Hanbok in the later Chosun Dynasty and modern has common properties of 'Planar Seperation' and 'Determinate'. Women's Hanbok belongs to 'Planar Seperation', because the effect cognized to figure and ground. can be found between small parts and whole of Jegori, or can be found between the head and face. Jeuori and waist band, and Chima and under ware. Further more. it can be classified into 'Determinate'. because it use textiles which have no pattern un it or which show a subtle surface effect by texture changing.

• Applied Microscopy
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• 제20권2호
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• pp.127-159
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• 1990

This study was investigated to elucidate the effect of chlorambucil on the heart in aging rats. Male rat ranging in age from 3 to 36 months were used. Each age groups(3, 6, 12, 18, 24, 36 months) included control and chlorambucil treated rats. As a part of the study, the ultrastructural changes in the left ventricular myocardial cells were described by using the qualitative and morphometric techniques. The results are summarized as follows. Age associated ultrastructural changes included: an increase in vacuoles, protrusion of plasma membranes, lipid droplets, and lipofuscins in myocardium of control groups. These changes which begin to occur at 12 months and continue through 36 months. At the 36 months some instance of unusual formation of contraction band and separation of intercalated discs were encountered. Morever, these changes and contents with chlorambucil treatment were remarkably increased in comparison with control groups. Age-dependent changes of control group measured with morphometry were not observed in the volume densities of mitochondria and myofibrils. But there was increase in interstitium. On the other hand decrease in sarcoplasmic reticulum and T-tubule system. In chlorambucil treated groups, volume densities of mitochondria and interstitium were increased in comparison with those of the control groups. But sarcoplasmic reticulum and T-tubule system were remarkably decreased.

• 한국측량학회지
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• 제36권5호
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• pp.343-353
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• 2018

Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

• 대한의생명과학회지
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• 제16권3호
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• pp.201-206
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• 2010

In order to develop procedures for the rapid isolation of recombinant sugar transporter in functional form from away from the endogenous insect cell transporter, gene fusion techniques were exploited. Briefly, BamH1-digested human HepG2 type glucose transport protein cDNA was first cloned into a transfer vector pBlueBacHis, containing a tract of six histidine residues. Recombinant baculoviruses including the human cDNA were then generated by allelic exchange following transfection of insect cells with wild-type BaculoGold virus DNA and the recombinant transfer vector. Plaque assay was then performed to obtain and purify recombinant viruses expressing the human transport protein. All the cell samples that had been infected with viruses from the several blue plaques exhibited a positive reaction in the immnuassay, demonstrating expression of the glucose transport protein. In contrast, no color development in the immunoassay was observed for cells infected with the wild-type virus or no virus. Immunoblot analysis showed that a major immunoreactive band of apparent Mr 43,000~44,000 was evident in the lysate from cells infected with the recombinant baculovirus. Following expression of the recombinant fusion protein with the metal-binding domain and enterokinase cleavage site, the fusion protein was recovered by competition with imidizole using immobilized metal charged resin. The leader peptide was then removed from the fusion protein by cleavage with porcine enterokinase. Final separation of the recombinant protein of the interest was achieved by passage over $Ni^{2+}$-charged resin under binding conditions. The expressed transport protein bound cytochalasin B and demonstrated a functional similarity to its human counterpart.

• 한국정보통신학회논문지
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• 제15권9호
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• pp.1840-1846
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• 2011

FM-CW 레이다 시스템에서는 이동 목표물 및 기상 현상 등의 정밀한 원격탐지를 위하여 대상 목표물의 거리 및 이동 속도에 따른 주파수 변이 와 수신 신호의 크기 정도를 정확하게 추출하여야 한다. 따라서 이러한 목적으로 최종 수신 단에서 얻어진 비트 신호에 대한 스펙트럼 추정을 하게 된다. 그러나 대부분의 레이다 운용환경에서는 매우 큰 클러터 반사가 나타나게 되며 레이다 시스템에서의 위상잡음은 이러한 강력한 클러터들뿐만 아니라 목표물반사 신호의 스펙트럼들도 추가적으로 확산시키게 된다. 따라서 본 논문에서는 이러한 위상잡음이 클러터 및 목표물 신호의 비트 스펙트럼에 미치는 영향을 분석하였다. 위상잡음의 특성에 따라 클러터와 비트신호가 확산되며 그정도에 따라 인접신호의 분리 가능정도가 결정됨을 확인할 수 있다.

• 한국환경복원기술학회지
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• 제4권2호
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• pp.36-44
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• 2001

The main purpose of this study was to classify forest vegetation effectively using Landsat Thematic Mapper data(June, 1994) in mountainous region. The research area was the Mt. Wolak Experimental Forest of Chungbuk National University, near Chungju and Jecheon city, Chungcheongbuk-do. To classify forest vegetation effectively, Normalized Difference Vegetation Index(NDVI) was used to reduce topographic effects. This NDVI was modified and transformed to the value of 0 to 255, and then the modified values were combined with other Landsat Thematic Mapper bands. To classify forest and land cover types, unsupervised classification method was used. The results of this study are summarized as follows. 1. Combinations of band "3, 5, NDVI" in Landsat Thematic Mapper data showed a good separation with high accuracy. The expected classification accuracy was 95.1% in Landsat Thematic Mapper data. 2. The Land Cover types were classified into six groups : coniferous forest, deciduous forest, mixed forest, paddy and grass, non-forest, and other undetectable areas. As these classified results were compared with the reconnaissance survey and aerial black and white infrared photographs, the overall classification accuracy was 76.5% in Landsat Thematic Mapper data. 3. The portion of non-forest in Mt. Wolak area was 1.9%. The percentages of coniferous, deciduous and mixed forests were 30.9%, 35.7% and 26.4%, respectively. 4. As these classified results were compared with other reference data, the percentages of coniferous, deciduous and mixed forests increased, but the portion of non-forest was exceedingly diminished. These differences are thought to be from the different research method and the different season of received Landsat Thematic Mapper data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.213-213
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• 2013

Even weak van der Waals (vdW) adhesion between two-dimensional solids may perturbtheir various materials properties owing to their low dimensionality. Although the electronic structure of graphene has been predicted to be modified by the vdW interaction with other materials, its optical characterization has not been successful. In this report, we demonstrate that Raman spectroscopy can be utilized to detect a few % decrease in the Fermi velocity ($v_F$) of graphene caused by the vdW interaction with underlying hexagonal boron nitride (hBN). Our study also establishes Raman spectroscopic analysis which enables separation of the effects by the vdW interaction from those by mechanical strain or extra charge carriers. The analysis reveals that spectral features of graphene on hBN are mainly affected by change in vF and mechanical strain, but not by charge doping unlike graphene supported on $SiO_2$ substrates. Graphene on hBN was also found to be less susceptible to thermally induced hole doping.