• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.173-173
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• 1999

The initial growth mode of Nb on Ag(110) in sub-monolayer region is studied using Scanning Tunneling microscopy. E-beam evaporated Nb is deposited onto the substrate at RT, and STM measurements are carried out at RT and 78K. With Nb being immiscible in bulk Ag, 3D islands formation begins at early stage and no particular ordered structure is found. At very low coverages, however, many interesting phenomena are observed in association with Nb clusters. Small Nb clusters as deposited displays very strong size dependence against atom-manipulation by the STM tip. In addition, the apparent corrugation of clusters below the critical size exhibits dramatic dependence on the imaging bias, disappearing completely over a wide range of the bias. Possible physical mechanism responsible for such behavior will be discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2538-2541
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• 2009

H.264/AVC High 4:4:4 Intra/Predictive profiles supports RGB 4:4:4 sequences for high fidelity video. RGB color planes rather than YCbCr color planes are preferred by high-fidelity video applications such as digital cinema, medical imaging, and UHDTV. Several RGB coding tools have therefore been developed to improve the coding efficiency of RGB video. In this paper, we propose a new method to extract more accurate correlation parameters for inter-plane prediction. We use a searching method to determine the matched macroblock (MB) that has a similar inter-color relation to the current MB. Using this block, we can infer more accurate correlation parameters to predict chroma MB from luma MB. Our proposed inter-plane prediction mode shows an average bits saving of 15.6% and a PSNR increase of 0.99 dB compared with H.264 high4:4:4 intra-profile RGB coding. Furthermore, extensive performance evaluation revealed that our proposed algorithm has better coding efficiency than existing algorithms..

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.2081-2085
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• 2012

Background: To investigate the value of ultrasound elastography (UE) in the differentiation between benign and malignant enlarged cervical lymph nodes (LNs). Methods: B-mode ultrasound, power Doppler imaging and UE were examined to determine LN characteristics. Two kinds of methods, 4 scores of elastographic classification and a strain ratio (SR) were used to evaluate the ultrasound elastograms. Results: The cutoff point of SR had high utility in differential diagnosis of benign and malignant of cervical lymph nodes, with good sensitivity, specificity and accuracy. Conclusion: UE is an important aid in differential diagnosis of benign and malignant cervical LNs.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.25-28
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• 2007

Precise digital elevation model (DEM) is an important issue in coastal area where DEMs in a time series are especially required. Although LIDAR system is useful in coastal regions, it is not yet popular in Korea mainly because of its high surveying cost and national security reasons. Recently, precise coastal DEM have been made using radar interferometry, waterline method. One of these methods, Spaceborne imaging radar interferometry has been widely used to measure the topography and deformation of the Earth. We acquired ALOS PALSAR FBD mode (Fine Beam Dual) data for evaluating the quality of interferograms and their coherency. The purpose of this study is construction of DEM using the ALOS PALSAR data using radar interferometry and analysis of surface characteristics by coherence and magnitude map over the Ganghwado and Siwha tidal flats and near coastal lands.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.85-89
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• 1999

FDE panel was successfully fabricated through the integration of a 0.7" diagonal Si-based Mo-tip FEA with 25${\times}$25 pixels, Y2O3:Eu or ZnO:Zn phosphor screen, and vacuum sealing through an exhausting glass tube, including a getter. The panel system was driven by an external driver circuit having pulse width modulation(PWM) driving scheme. Before character imaging, it was stabilized through tip aging by slowly increasing a pulse-mode emission current and phosphor aging by a coulombic charging process. After aging, luminescent characteristics such as emission uniformity, charging and arcing phenomena were shown to be improved significantly.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.99-106
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• 1998

Recently, scientists introduced a new type of microscope capable of investigating nonconducting surfaces in an atomic scale, which is called AFM (Atomic Force Microscope). It was an innovative attempt to overcome the limitation of STM (Scanning Tunnelling Microscope) which has been able to obtain the image of conducting surfaces. Surfaces of samples are imaged with atomic resolution. The AFM is an imaging tool or a profiler with unprecedented 3-D resolution for various surface types. The AFM technology, however, leaves a lot of room for improvement due to its delicate and fragile probing mechanism. One of the room for improvements is gap control between probe tip and sample surface. Distance between probe tip and sample surface must be kept in below one Angtrom in order to measure the sample surface in Angstrom resolution. In this paper, AFM system modeling, experimental system identification and control scheme based on system identification are performed and finally sample surface is measured by home-built AFM with such a control scheme.

• Journal of Chest Surgery
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• v.16 no.4
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• pp.485-491
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• 1983

From July 1966 to July 1983, sixteen atrial myxomas in fifteen patients were seen at Severance Hospital. Fifteen of the sixteen myxomas were located in the left atrium and one in the right atrium. All the cases except three were correctly diagnosed preoperatively. Presently, M-mode and two-dimensional echocardiography are utilized as safe, reliable, and noninvasive imaging modalities. Echocardiography provided an accurate diagnosis in twelve cases since November 1977. In all cases, myxoma were excised successfully. On patient had reoperation and mitral valve replacement on postoperative first day due to persist mitral regurgitation after excision of left atrial myxoma. One patient had recurrence requiring reoperation 37 months after primary operation. Follow up results of each patient were excellent.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.715-722
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• 2012

A structural health monitoring (SHM) technique for locating impact position in a composite plate is presented in this paper. The technique employs a single sensor and spatial focusing properties of time reversal (TR) and inverse filtering (IF). We first examine the focusing effect of back-propagated signal at the impact position and its surroundings through simulation. Impact experiments are then carried out and the localization images are found using the TR and IF signal processing, respectively. Both techniques provide accurate impact location results. Compared to existing techniques for locating impact or acoustic emission source, the proposed methods have the benefits of using a single sensor and not requiring knowledge of material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in the SHM of plate-like structures.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.479-485
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• 2002

We propose a vector analysis for designing multimode-interference power splitters, which can show an arbitrary splitting ratio. Power splitting is a fundamental characteristic in integrated optical circuits and its value would be multiplied for many applications if the splitting ratio could be selected freely. Since the vector analysis utilizes a graphical method based on the previously-reported mathematical results of multimode interference, it shows an excellent advantage especially for designing power splitters with an arbitrary splitting ratio.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4
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• pp.67-71
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• 1998

초음파 선형트랜스듀서에서 제한회절음장은 영상깊이에서 다른 방향으로 진행하는 평면파들의 선형적인 중첩으로부터 구한다. 제한회절음장을 구현하기 위한 송신음장은 영상 깊이를 지나가는 평면파들의 공간적인 확장으로부터 구해지는데 실제의 하드웨어로 구현하 기 어렵다. 본 논문은 진행방향이 다른 pulsed mode 평면파를 각각 송신한 후, 얻어진 데이 터로부터 합성집속 방법에 의하여 제한회절빔을 구현하였다. 제안한 방법은 모든 송신소자 에서 발사되는 음장의 크기가 동일하므로 송신전력이 증가하여 신호대잡음비와 명암비를 증 가시키며 간단한 하드웨어로 구현이 가능하다. 시뮬레이션 결과는 송신은 한점집속, 수신은 동적집속을 사용하는 기존의 방법과 비교하여 주엽(mainlobe)의 폭과 부엽(sidelobe)의 크기 관점에서 우수함을 증명하였다.