• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.183-194
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• 2011

Synthetic aperture radar (SAR) is widely used because of high resolution imaging capability in all weather and day/night condition. In this paper development of Spotlight SAR simulator is proposed for image quality analysis. Proposed SAR simulator is based on the SAR system design parameters so that SAR image performance can be expected which is essential throughout the full system development procedure from the initial concept design stage to the final in-flight calibration and validation stage. The raw data of ideal point target is first generated by taking account of the flight and imaging geometry and the various SAR system design parameters, and the Spotlight image formation algorithm is implemented in order to obtain the point target response. Finally the image quality of the generated raw data is analyzed in terms of spatial resolution, peak to sidelobe ratio and integrated sidelobe ratio.

• Korean Institute of Interior Design Journal
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• v.15 no.3 s.56
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• pp.92-101
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• 2006

This study examines placeness of the living space on the basis of Schulz's existential space and inquires into the expressional features of placeness by analyzing cases. Results of this study have shown that placeness of living space is formed by three factors as follows. First, the living space with placesness maintains inner order which structuralizes surroundings. Second, it expresses its identity through innate shape that reflects surroundings. Third, inner space has innate identity and it is much related to characteristics personality of a resident, environmental and psychological factors. It is as follows that concrete features of existential placeness shown in analyzing cases of Botta and Moore's works. There are concrete expressional features of placeness in the housing of Botta, and one is to keep order of inner space the horizontal and vertical axis reflected surroundings. Another is to show existence feeling as the shape of a stable singular mass with surroundings and regional properties. The third is to value innate features of each space inside housing and particularly to acquire placeness as combining phenomenological characteristic of light. There are concrete expressional features of placeness in the housing of Moore, and first, strong centrality formed in the inside is emphasized as extending to outside environment. Second, existence feeling is acquired as familiar form using the shape and material considered surroundings. Third, the personality of a resident is positively reflected in the design. Besides, placeness is acquired by goods and furniture as positively considering environmental and psychological sides.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.721-725
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• 2007

A fiber optic based weight sensor has fabricated using a fiber Bragg grating with a weight sensitive. The sensing concept exploits the inherent characteristics of the FBG and is based on the strain effect induced in the fiber Bragg grating through. A direct indication of the weight level is given by the shift of the Bragg wavelength caused by the expansion of the sensing material. A FBG behaves like a spectral filter which has inherent characteristics that render it very sensitive to strain and temperature. The sensing principle is also based on the strain effect induced in the FBG through the caused by the weight. The experimental setup used for the initial investigation to characterize the mass response of the sensor. The transmitted signal from the sensor was monitored using an optical spectrum analyzer with a resolution bandwidth of 0.4nm. In this paper, we presented the spectral characterization and shaping of FBG by scanning a mass element that affects a small grating fraction at a time, without permanent effects on the optical fiber when the various wavelength and strain is removed. That is, destruction when the optical fiber for weight is physically damaged.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.24-24
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• 2015

최근 생체재료의 개발이 눈부시게 발전되고 생체적합성이 우수한 표면을 요구함에 따라 생체재료의 표면처리에 대한 연구가 활발히 진행되고 있다. Laser Deposition법은 항공기 부품제조 분야에 주로 사용되고 있으며 최근에 오하이오 주립대 타이타늄합금연구센터를 중심으로 표면처리에 관한 연구가 주로 이루어졌다. 특히 이를 이용하여 치과재료의 표면처리에 응용을 시도하였다. 치과에서 응용될 수 있는 경우는 주로 임플란트는 부분 또는 완전 무치악 환자의 보철수복에 사용되는 보철물의 제작등에 사용될 수 있으며 이중에서도 특히 생체용 임플란트의 표면처리응용으로 임플란트와 조직간의 접합성을 개선하는 표면처리법으로 연구되었다. 임플란트의 성공과 실패는 물성적인 측면에서 임플란트의 형태, 표면거칠기 및 표면처리방법, 초기하중 등에 의하여 좌우되며 임플란트 재료에 작용하는 응력차폐는 생체적합성을 좌우하는 큰 요인이 되고 있다. 이를 위하여 저 탄성계수합금을 설계하지만 하중을 버티는 강도가 낮아지는 단점이 있어 레이저증착법을 이용하여 임플란트재료인 Ti6Al4V합금에 탄성계수가 낮은 Ta, Nb등을 코팅하는 방법을 통하여 이를 해결하고자하는 시도가 이루어지고 있다. 이 방법은 최근의 3D 프린팅의 원리가 되고 있다. 따라서 발표에서는 Laser Deposition방법을 이용하여 치의학분야에서 응용되고 있는 예를 강연하고 응용 가능 분야에 대하여 토론 하고자한다. 또한 펨토레이저를 이용하여 생체합금의 표면처리는 생체활성화를 더욱 증진시키며 이를 위하여 많은 연구 수행되고 있다. 본 발표에서는 매식용 합금 표면에 펨토레이저를 이용하여 텍스춰링하여 세포가 잘 성장 할 수 있는 크기의 조절함으로써 기존의 표면처리와는 다른 효과를 얻을 수 있는 장점을 알아본다. 펨토레이저를 이용하면 여러 가지 형태의 텍스춰링이 가능하며 원형, 사각형등등 자유자제로 형태의 묘사가 가능하고 깊이 또한 쉽게 조절할 수 있는 장점이 있다. 지금까지는 표면 개질에 사용되는 레이저는 주로 Nd:YAG 레이저의 파장을 반으로 줄인 녹색레이저 (${\lambda}=532nm$)를 사용하거나, 자외선파장영역의 레이저를 사용하는 경우가 일반적으로 가장 보편화되었다. 이를 이용하여 제조된 Ti합금에 펨토 초(10-15 second) 펄스폭 대역을 갖는 레이저를 이용하여 나노크기의 미세 요철을 표면에 형성한 후, 나노튜브를 형성하여 그 표면특성의 변화를 알아보고 펨토레이저가 의료분야에 적용되고 있는 예를 살펴보고자 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.1
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• pp.15-22
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• 2005

In this paper, we propose a face recognition system by using the CCD color image. We first get the face candidate image by using YCbCr color model and adaptive skin color information. And we use it initial curve of active contour model to extract face region. We use the Eye map and mouth map using color information for extracting facial feature from the face image. To obtain center point of Log-polar image, we use extracted facial feature from the face image. In order to obtain feature vectors, we use extracted coefficients from DCT and wavelet transform. To show the validity of the proposed method, we performed a face recognition using neural network with BP learning algorithm. Experimental results show that the proposed method is robuster with higher recogntion rate than the conventional method for the rotation and scale variant.

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.61-69
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• 2017

The commercial development of unconventional gas is pursued in North America because it is more feasible owing to the technology required to improve productivity. Shale reservoir have low permeability and gas production can be carried out through cracks generated by hydraulic fracturing. The decline rate during the initial production period is high, but very low latter on, there are significant variations from the initial production behavior. Therefore, in the prediction of the production rate using deterministic decline curve analysis(DCA), it is not possible to consider the uncertainty in the production behavior. In this study, production rate of the Eagle Ford shale is predicted by Arps Hyperbolic and Modified SEPD. To minimize the uncertainty in predicting the Estimated Ultimate Recovery(EUR), Monte Carlo simulation is used to multi-wells analysis. Also, kernel density function is applied to determine probability distribution of decline curve factors without any assumption.

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.224-236
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• 2003

This study tries to identify the terms which shared the same meaning with a present-day geographical concept region, or jibang(地方) in Korean, Prior to the initiation of modem geography. The analysis of the annals of the pre-modem political regimes and the earliest geography textbooks ends up with the terms oe(外), bang(方), oebang(外方), ji(地面). These terminologies, although having had almost similar meanings that region intends, nonetheless deliver somewhat different connotation depending on the context and times in and during which they were used. Another finding of significance is that region and jibang, both central .words in contemporary geography, began to be used only after the introduction, by way of Japan, of modem geography in the early 20th century. The colonial experience and subsequent political and social turmoil, however, results in careless uses of the terms in geography teaching and research. Efforts need to be continued to address the problems of misuse of these basic terms and, by doing so, to raise geographical pursuits on a right track.

• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.131-142
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• 1999

In this study, one and semi-two dimensional numerical models were applied to study on the hydraulic and sedimentologic characteristics of upstream and downstream channel section near the Buyeo intake towers. The HEC-6 model was applied for the simulation of one dimensional sediment movement from 1988 to 1996, and GSTARS model was applied for the simulation of semi-two dimensional sediment movement for the same period. After the verification of accuracy of HEC-6 and GSTARS models, the models were applied again to predict the sediment movement near intake towers from 1988 to 2001. In this case, measured channel section of 1988 was used as an initial channel condition, and used to predict the long-term variation of channel section of 2001 after 13 years since 1988. The simulation results show that the channel bed is sedimented and eroded repeatedly in the main channel of overall study area, and that channel bed is getting elevated in the near Buyeo intake towers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.169-174
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• 2011

Acoustic emission (AE) signals were detected and analyzed in real time during the polymerization shrinkage of composite resin restoration in an artificial dental ring with a class I cavity. Most AE hit events were observed in the initial curing period of the 1st region with high contraction rate. The range of the $2^{nd}$ region for the stainless steel specimen was shorter than that for the PMMA specimen but longer than that for the human dentin specimen. AE hit events showed a blast-type signal having an amplitude in the range of 25.45 dB and a frequency band of 100.200 kHz or 240.300 kHz. These values of amplitude and frequency indicated the fracture of resin or of the adhesive layer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.51-56
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• 1983

In the stability problem of the U-grooved plate, it has a circular hole, the site of the hole determines some different deformation mode when it was loaded. To determine the optimal position of the circular hole-center which not to get large distortion of the hole itself, in this paper, we studied the distributions of stresses in the neck area between hole and U-groove and the distortion mode of the deformed hole by B.E.M(Boundary Element Method) and compared with experimental results in four cases. For a distributed load, according to the center of the hole moves closer to the U-groove center (c.-c. line), the shape of the circular hole was transformed to the elliptical one(it's major axis perpendicular to the c.-c. line). In this problem, the results by Boundary Element Method was well accorded with Experiments.