• Korean Journal of Crystallography
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• v.3 no.2
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• pp.85-97
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• 1992

EBFZM( Electron Beam Floating Zone Melting) 법을 이용하여 몰리브덴에서의 금속계 불순물과 침입형 불순물의 정련기구 및 단결정 성장기구를 연구하 였다. Fe, Cr, Co등의 금속계 불순물은 몰리브덴과의 평형증기압의 차이에 따른 불순물의 선택적 증발에 의하여 우수한 정련효과를 나타내며, 몰리브덴보다 응점이 높은 Ta, W는 잘 제거되지 않았다. 한편 대역 정제에 의한 정련효과는 미약함을 확인하였다. EBF ZM은 C,0,N등의 침입형 불순물의 정련에도 효과적 이었다. 본 연구의 모든 조건에서 몰리브덴은 단결정으로 성장하였으며 2차 재결정 epitaxy에 의한 단결 정 성장기구가 제시되었다. 몰리브덴 단결정 내의 전 위밀도는 strain-anneal법에 의한 단결정의 경우보다 높았으며,본 실험의 열처리 조건에서는 변화하지 않았다. The purification and single crystal growth mechanisms of molybdenum were analysed in EBFZM ( electron beam floating zone melting). Metallic impurities of Fe, Cr, Co were purified efficiently but Ta and W were not removed well in this study. It was due to a preferential evaporation of the elements caused by the difference in equillibrium vapor pressure between the elements and molybdenum. The pu- rification effect by zone refining was not significant. The EBFZM also refined the interstitial impurities of C, 0 and N, effectively. The single crystals of molybdenum were grown regardless of the experimental conditions and the secondary recrystallization epitaxy was surge sled as a growth mechanism. The dislocation density in single crystal was higher than that by strain-anneal method, and was not reduced by heat treatments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.11
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• pp.77-84
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• 2003

This paper presents a multi-functional microstrip spital antenna that operates in dual frequency bands. Several types of beam shape can be selected by controlling the phase difference of two spiral arms with the phase shifters located on each feed line. It has a normal beam at the lower frequency band, and four different patterns at the higher frequency band: normal beam, conical beam and two types of tilted beam. The antenna exhibits more than 10% of bandwidth at each band. The antenna is fabricated with conductor backed electromagnetic absorber in order to attain unidirectional radiation pattern and confirmed the multi-functionality by measurements.

• Journal of the Korea Society of Computer and Information
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• v.20 no.3
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• pp.75-80
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• 2015

Vulnerability management is in compliance with security policies, and then, this is to ensure the continuity and availability of the business. In this paper, the application vulnerability management and IT infrastructure of the system is that it must be identified. And a viable vulnerability management plan should be drawn from the development phase. There are many that are not defined vulnerability in the area of identification and authentication, encryption, access control in identification and classification of vulnerabilities. They define the area without missing much in technical, managerial, and operational point of view. Determining whether the response of the identified vulnerability, and to select a countermeasure for eliminating the vulnerability.

• Information Systems Review
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• v.15 no.3
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• pp.141-149
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• 2013

When evaluating effectiveness of a government's supporting program, there is a tendency to simply compare the performances of the treated before and after the program or to compare the differences in the performances of the treated and untreated before-after the program. However, these ways of evaluating effectiveness have problems because they can't account for environmental changes affecting the treated or effects coming from the differences between the treated and the untreated. Therefore, in this paper, sequential applications of PSM and DID are suggested as a means to overcome those problems. It turns out that this approach enables us to eliminate self-selection bias and thus better evaluate effectiveness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.48-48
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• 2009

최근 나노광전소자 응용에 큰 관심을 받는 물질인 산화물 나노선은 앞으로 불어 올 나노소재 시대를 여는 선두 물질이다. 이러한 산화물 나노선 가운데 가장 큰 관심을 받는 물질로는 산화아연 나노선을 들 수 있다. 삼화아연 나노선은 상온에서 큰 엑시톤 결합에너지 및 큰 밴드갭을 가지고 있으며 투명성 및 소자구동시 안정성을 지니고 있어 그 응용이 기대된다. 하지만 이러한 나노선을 이용한 광전소자 응용은 bottom-up 방식을 기초로 한 대면적 소자제작이 어렵다. 이러한 bottom-up 방식의 나노소자 제작에서 필요한 나노선 성장기술은 금속 catalyst 없이 대면적 성장, 나노선 수직어레이, 나노선의 고온성장, 기판 사이에 발생하는 자발적 계면층 제거 등으로 대표된다. 또한 나노선의 결정성 및 광특성 향상을 위해서는 고온성장이 불가피한데, 실리콘 기판과 같이 격자상수 불일치도가 큰 기판에서는 나노선 성장이 이루어지지 않고 다시 탈착되어 구조물이 성장되지 않는다. 본 연구에서는 선택적 삼원계 단결정 씨앗층을 이용하여 길이/직경 비가 매우 향상된 MgZnO 나노와이어를 interfacial layer 없이 수직으로 고온에서 성장하여 산화물 전계방출 에미터로서의 가능성을 확인하였다.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.69-71
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• 2000

Redox-active calix[4]arenes with carboxylic acid and disulfide groups were prepared and spontaneous deposition on silver and gold surfaces was observed. Owing to their unusual structure, the calix[4]arenes exhibit selective affinity fur alkaline earth metal ions in aqueous media. When annular ionophores are immobilized on the surface, voltammetric and spectroscopic studies show the entrapment of metal ions. Furthermore, it was possible to reversibly capture and remove the ions using strong chelating agents such as ethylenediaminetetraacetic acid (EDTA).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.109-112
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• 2008

최근 MPEG(moving picture experts group)에서 표준화를 진행하고 있는 3차원 비디오 시스템은 다시점 영상과 깊이영상을 동시에 이용하여 사용자가 임의의 시점을 선택하거나 스테레오스코픽 장치와 같은 3차원 영상 재생장 치를 동해 3차원 영상을 제공하는 차세대 방송 시스템이다 제한된 시점수를 이용하여 보다 많은 시점의 영상을 제공하려면 중간시점의 영상을 보간하는 장치가 필수적이다. 이 시스템의 입력정보인 깊이값을 이용하면 시점이동을 쉽게 할 수 있는데, 보간한 영상의 화질은 이 깊이값의 정확도에 따라 결정된다. 깊이맵은 대개 컴퓨터 비전을 기반으로 한 스테레오 정합기술을 이용 획득하는데, 객체의 경계와 같은 깊이값 불연속 영역에서 주로 깊이값 오류가 발생하게 된다. 이런 오류는 생성한 중간영상의 배경에 원치 않는 잡음을 발생시킨다. 기존의 방법에서는 측정한 깊이법의 객체 경계와 영상의 객체 경계가 일치한다는 가정으로 중간영상을 합성했다. 그러나 실제로는 깊이값 측정 과정에서 두 가지 경계가 일치하지 않아 전경의 일부분이 배경으로 합성되어 잡음을 발생하는 것이다. 본 논문에서는 깊이맵을 기반으로 중간시점의 영상을 보간할 때 발생하는 경계 잡음을 처리하는 방법을 제안한다. 중간영상을 합성할 때 비폐색 영역을 합성한 후 경계 잡음이 발생할 수 있는 영역을 비폐색 영역을 따라 구별한 다음, 잡음이 없는 참조 영상을 이용함으로써 경계 잡음을 처리할 수 있다. 실험 결과를 통해 배경 잡음이 사라진 자연스러운 합성영상을 생성했다.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.81-85
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• 1998

Location Registration and deregistration is necessary to mobility management in a Mobile Communication networks when a mobile phone moves between location registration areas. After considering several deregistration schemes, a sample scheme that eliminate network traffic is chosen. However, this scheme may delete valid registration record, so the size of location registration database must be sufficiently large to ensure low probability that a valid records are deleted. This paper describes an analytic model to determine the size of location registration database for a location registration area in this simple scheme. The simulation results of analytic model show that the size of database must 3-5 times than the expected number of mobile phones in a location registration area.(Mobile, Communications, Location, Deregistration, Database)

• Journal of Environmental Science International
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• v.8 no.3
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• pp.393-397
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• 1999

Among various reactions which metal sulfides can undergo in the reducing environment, the lattice exchange reaction was examined in a attempt to selectively remove heavy metal ions contained in the Fe-Coagulants acid solution. We have examined Zeta potential along with pHs to investigate surface characteristics of ${FeS}_{(s)}$. As a result of this experiment, zero point charge(ZPC) of FeS is pH 7 and zeta potential which resulted from solid solution reaction between Pb(II) and ${FeS}_{(s)}$ is similar to that of ${PbS}_{(s)}$. Solubility characteristics of ${FeS}_{(s)}$ is appeared to that dissolved Fe(II) concentration increased in less than pH 4, and also increased with increasing heavy metal concentration. Various heavy metal ions(Pb(II), Cu(II), Zn(II)) contained in Fe-coagulants acid solution were removed selectively more than ninety-five percent in the rang of pH 2.5~10 by ${FeS}_{(s)}$. From the above experiments, therefore, We could know that the products of reaction between heavy metal ions and $FeS_{(S)}$ are mental sulfide such as $PbS_{(S)}$, $CuS_{(S)}$ and $ZnS_{(S)}$.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.213-221
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• 2007

This paper showed how to analysis the object-based classification for wildfire fuel type map using Hyperion hyperspectral remote sensing data acquired in April, 2002 and compared the results of the object-based classification with the results of the pixel-based classification. Our methodological approach for wildfire fuel type map firstly processed correcting abnormal pixels and atypical bands and also calibrating atmospheric noise for enhanced image quality. Fuel type map is characterized by the results of the spectral mixture analysis(SMA). Object-based approach was based on segment-based endmember selection, while pixel-based method used standard SMA. To validate and compare, we used true-color high resolution orthoimagery.