• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.352-352
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• 2010

일반적인 근접장 현미경은 광섬유 팁 (tip) 끝에 수십 nm 크기의 구멍을 이용하여 근접장을 발생시키거나 측정한다. 근접장은 전파되는 빛보다 미세한 구조의 정보를 반영하게 되는데 수십 나노미터의 구멍대신 FRET (fluorescence resonance energy transfer)이라는 현상을 근접장 현미경에 적용하고자 한다. 10 nm 이내의 거리에서 상호작용을 하는 이 현상을 이용하여 광학적 분해능을 향상시킬 수 있다. FRET 현상의 도우너(donor)로서는 양자점을 사용하였으며 억셉터(acceptor) 로서는 Cy5 염료를 사용하였다. 팁으로는 광섬유를 에칭한 팁에 Cy5 염료를 코팅한 팁과 광섬유의 코어(core) 부근에 양자점이 포함된 광 폴리머를 응고시켜서 만들어진 팁을 사용하였다. 팁에 위치한 도우너와 시료로 사용되는 억셉터를 FRET 상호 작용 거리 내로 접근시키기 위하여 tuning fork를 이용한 shear force control을 사용하였다. 한 점에서의 접근 과정에서 FRET의 현상의 특징으로서 도우너인 양자점의 형광이 약해지고 Cy5의 형광이 강해지는 것을 측정하였다. 또한, 양자점을 Cy5 염료에 근접시켰을 때 발광 생존시간 (lifetime)이 짧아지는 것을 관찰하여 FRET 현상을 재확인 하였다.

• Progress in Medical Physics
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• v.15 no.3
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• pp.156-160
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• 2004

An essential quality assurance (QA) procedure in high dose rate (HDR) remote after-loading brachytherapy is that of the verification of the Ir-192 HDR source positioning accuracy. A number of methods using mechanical rulers or autoradiograph and video cameras have been reported to check the positional error of the Ir-192 source. In this study, the feasibility of a CMOS (Complementary Metal Oxide Semiconductor) PC camera, with a fluorescent screen, was investigated. The agreement between the planned and measured dwell position was better than 1 mm and dwell times better than 0.4 sec. Our results indicate that the CMOS PC camera system could be used as a QA tool for the on-line determination of the source position and dwell time.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.692-698
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• 2006

점점 더 많은 디지털 카메라와 휴대폰이 고해상도 카메라가 장착되고 대용량의 저장공간이 제공되면서 사용자들의 사진촬영 빈도가 증대하고 있다. 조만간 휴대폰의 저장된 사진을 효과적으로 관리하고 브라우징할 수 있는 기술이 필요한 시기가 올 것이다. 본 논문은 휴대폰이나 디지털 카메라 혹은 카메라가 장착되어 사진을 찍을 수 있는 모든 형태의 휴대단말에서 촬영된 개인사진을 지리적 위치정보를 이용하여 자동으로 분류하는 시스템을 제시한다. 기존의 시간정보를 이용하여 촬영시간의 근접성을 이용해 순차적으로 자동 분류하는 시스템과는 달리 위치정보를 이용하여 촬영위치에 따라 비순차적으로 자동 분류한다. 촬영위치 근접성을 결정하기 위해 밀도기반 클러스터링 알고리즘을 사용하여 전체 사진을 대분류하고 기존의 자동사진 분류방식에서는 다루지 않았던 일상사진과 비일상사진을 분류하고, 대분류된 사진을 시간정보를 이용하여 소분류 함으로서 자동 사진분류 성능을 높이고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.539-544
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• 2016

This paper improves Sherman's two-pulse method for angle estimation of two unresolved targets in phase comparison monopulse radar. The proposed method provides the angle information with only a single-pulse measurement instead of two pulses. The proposed method can estimate a single-target angle by single-target indicator, in contrast with previous techniques. The accuracy of angle estimation for proposed method is demonstrated by simulations.

• Journal of Technology Innovation
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• v.19 no.2
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• pp.153-184
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• 2011

This paper investigates what kind of technological partner firms want to cooperate with in terms of partner location. Two geographical factors are considered. One is geographical proximity, given the tradeoff between the effectiveness of knowledge spillovers in proximity and diverse knowledge absorption from geographically distant partners. The other is how many other firms are co-located with potential partners because it is known that clustering regions can create more technological outputs. Analysis on 2008 Korea Innovation Survey data finds that partner proximity is the single most important factor in choosing a cooperation partner. While firms that are located in a region crowded with related industries prefer proximate partners, others that are surrounded by unrelated industries are more likely to cooperate with distant partners. The findings suggest that geographical proximity matters in partner selection because it not only stimulates knowledge spillovers but also reduces costs involving R&D cooperation such as monitoring costs and information costs. Moreover, firms take into consideration both the benefits and risks of clustering regions. If there are so many unrelated firms that they create agglomeration diseconomies such as congestion costs and unintentional knowledge leakages, firms are more likely to try to find their cooperation partners in other regions.

• The Journal of the Acoustical Society of Korea
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• v.36 no.2
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• pp.100-107
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• 2017

The focused MVDR (Minimum Variance Distortionless Response) can be applied for source localization in near field. However, if the number of sensors are increased, it requires a large amount of calculation to obtain the inverse of the covariance matrix. In this paper we propose a focused MVDR method using that beam space is formed from output of far field beamformer at the subarray. The performances of the proposed method was evaluated by simulation. As a result of simulation, the proposed method has the higher spatial resolution performance then the conventional delay-and-sum beamformer.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.1-11
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• 2004

An experimental study was carried out to investigate the influence of flow conditions of a boundary layer on the near-wake of a flat plate. Various attaching positions of tripping wires were selected to change flow conditions on a boundary layer. Laminar, transitional, and turbulent boundary layer conditions at 0.98C from the leading edge are imposed to investigate the evolution of symmetric and asymmetric wake. An x-type hot-wire probe(55P61) is employed to measure at 8 stations of the near-wake region. Measured mean velocity distributions are presented in terms of similarity parameter. It is found that the symmetric wake collapses well to the universal profile in the central part of the wake. However, the universal profile is not suitable in describing an asymmetric wake.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.138-145
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• 2020

This study was conducted to identify the structural performance of the opening in a location close to the support point in the perforated beam system of steel beams. In addition, structural performance was determined through experiments on reinforced openings using vertical and horizontal steel plates. In the steel simple beam, it was found that the opening was in a position closer to the support point, half the height of the steel beam (D/2), which was more appropriate than the height of the steel beam (D). In addition, the reinforcement effect of horizontal steel plate was greater than that of vertical steel plate reinforcement. Structural performance was improved when there was no gap between openings and steel plates.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.151-162
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• 2000

The general properties of the NCBs, divided into A and F types according to their spectral types, have been presented. The evolutionary status of the F type near-contact binaries are closer to that of the contact systems, i.e., W UMa type binaries, if it is assumed that the evolution of the NCBs is governed by the thermal relaxation oscillation theory. The mass-radius relation, mass-luminosity relation and H-R diagram of the NCBs provide that the A type NCBs suffer from more active mass transfer than F types. The components of the NCBs ar still in main-sequence like W UMa type stars and their two components lines parallel to the ZAMS.

• Journal of KIISE:Databases
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• v.36 no.3
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• pp.198-214
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• 2009

Trajectories of RFID tags can be modeled as a line, denoted by tag interval, captured by an RFID reader and indexed in a three-dimensional domain, with the axes being the tag identifier (TID), the location identifier (LID), and the time (TIME). Distribution of tag intervals in the domain space is an important factor for efficient processing of a query for tracing tags and is changed according to arranging coordinates of each domain. Particularly, the arrangement of LIDs in the domain has an effect on the performance of queries retrieving the traces of tags as times goes by because it provides the location information of tags. Therefore, it is necessary to determine the optimal ordering of LIDs in order to perform queries efficiently for retrieving tag intervals from the index. To do this, we propose LID proximity for reordering previously assigned LIDs to new LIDs and define the LID proximity function for storing tag intervals accessed together closely in index nodes when a query is processed. To determine the sequence of LIDs in the domain, we also propose a reordering scheme of LIDs based on LID proximity. Our experiments show that the proposed reordering scheme considerably improves the performance of Queries for tracing tag locations comparing with the previous method of assigning LIDs.