• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.4
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• pp.231-238
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• 2006

Nondestructive examination for low pressure turbine disc in standard nuclear power plant using phased array technique was studied. For this purpose, disc mockups were made and notches were machined in the mockups. Detection and length sizing by different methods are compared. Depth of deep notches could be measured by using AATT(absolute arrival time technique) or RATT(relative arrival time technique) but shallow notches that must be detected in early stage couldn't be measured by these two methods. For this case, notch depth was estimated by using signal response angle range and preyed usefulness.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.847-853
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• 2006

In this paper, we designed VCO(voltage controlled oscillator} that is composed of a dielectric resonator and a varactor diode, and the PLDRO(phase locked dielectric resonator oscillator) that is combined with the sampling phase detector and loop filter. The results at 12.05 GHz show the output power is 13.54 dBm frequency tuning range approximately +/- 7.5 MHz, and power variation over the tuning range less than 0.2 dB, respectively. The phase noise which effects on bits error rate in digital communication is obtained with -114.5 dBc/Hz at 100 kHz offset from carrier, and The second harmonic suppression is less than -41.49 dBc. These measured results are found to be more improved than those of VCO without adopting PLL, and the phase noise and power variation performance characteristics show the better performances than those of conventional PLL.

• Journal of Korean Elementary Science Education
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• v.27 no.4
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• pp.385-398
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• 2008

The purpose of this study is to understand the effect of The Model of Phases of the Moon on conception changes for preservice teachers. The researcher interviewed two preservice teachers under the agreement with them on their participation in the research just before he performed a class using The New Model of Phases of the Moon. The post-interview with the same content as the pre-interview was preformed one month later. The main content of the interview is as follows; 'Explain the shape of the Moon by drawing it.', 'Explain the relative different position among the Sun, Earth, and Moon depending on phases of the Moon by drawing them.', 'What do you think of the cause of phases of the Moon?', 'Draw a picture to explain why we always see only one side of the moon.' The results of the research are as follows. First, the class with New Model of Phases of the Moon was able to perceive the relationship of Sun, Earth, and Moon in three-dimensions rather than in two-dimensions and it helped to change their misconception that the Moon's shadow causes the Moon's shape. Secondly, the class with New Model of Phases of the Moon helped preservice teachers understand better the different positional relationships among the Sun, Earth, and Moon depending on the Moon shapes. Third, the class adopting the New Model of Phases of the Moon help preservice teachers form scientific conceptions on the causes of phase change of the Moon. Fourth, the class with the New Model of Phases of the Moon is not appropriate for explaining the reason why only one face of the Moon is seen. Based upon the results above, the researcher realized the limitation of this model and suggested that this model would help learners understand phase change of the Moon and increase space perception ability.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.1
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• pp.111-118
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• 1998

Today Geo-Spatial Information System(GSIS) has developed and used more widely, and especially it has been more greatly asked for Land Information System as a part of GSIS. Now it has been planning and monitoring for remaking of cadastral maps by the Ministry of Government Administration and Home Affairs. But this is long term project because of the importance of itself. And then it has been needed to computerize cadastral maps for implementation of relative tasks and services. Cadastral maps have some problems; for example, map join in different scales, different administration boundary and so on. In this study General topology algorithm, Polygonization algorithm and Pseudo-topology algorithm was adapted in computerization of cadastral maps. This is called digital map. The area and shape of parcels do not change. As a result it was found that Polygonization algorithm is the best of 3 algorithm and General topology algorithm is the worst.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.1
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• pp.38-44
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• 2004

An experimental study for a crane hook was performed to investigate the stress distribution along a certain line where the maximum and minimum stresses to be developed. On this line, the isoclinic fringe and/or principal stress direction is constant. The crane hook was modeled into a 2-dimensional plate made of urethane rubber called 'Photoflex' The Photoflex is very sensitive to a load and has low photoelastic fringe constant. The Tardy compensation method with the fringe sharpening process and the 4-step phase shifting method, was used for the photoelastic technique. Experimental results by photoelasticity were compared with the calculated stresses from the simple curved beam theory and tile finite element analysis. Ail the results were close to each other.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.264-264
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• 1994

본 연구는 보리 씨앗에 존재하는 리보솜 불활성화 단백질(RIP) 의 삼차원 구조를 X-선 결정학 방법을 이용하여 밝히고, 그 결과로 분자 차원에서 기능을 이해하는 것을 목적으로 하고있다. 리보솜불활성화 단백질은 N-glucosidase 반응을 통하여 단백질 합성을 저해하기 때문에 세포를 죽일 수 있다. 따라서 암세포만을 특정적으로 인식하는 다른 물질과 결합시키면 암세포만을 특정적으로 죽일 수 있는 면역독소로 이용될 수 있다. 또, 최근에는 항바이러스의 작용을 함이 밝혀져 많은 연구가 진행되고 있다. 단백질 삼차원 구조 규명을 위해서는 여러가지 단계가 있는데 지난 번 과제까지 성공적으로 리보솜 불활성화 단백질의 대량 분리와 X-선 결정학의 필수 요건 좋은 결정을 길렀고, 이번에는 구조 해석을 위해 꼭 해결해야하는 위상문제를 극복하기 위하여 여러가지 실험을 진행하였다. 우선, 비슷한 구조인 피마자씨에서 분리한 Ricin의 A-체인과 미국자리공 잎에서 분리한 Pokeweed antiviral protein의 삼차원 분자좌표를 이용하여 분자치환법으로 위상문제 해결을 시도하였다. Ricin 의 A-체인을 이용하였을 때 분자의 위치가 정확히 찾아지지 않았고, 다른 모델인 Pokeweed antiviral protein을 이용하여 X-PLOR 프로그램내의 PC refinement법으로 분자치환을 시도하였다. Euler각도로 (187.37, 22.5, 311.94) 의 회전해 (Rotation solution) 를 가지고 있었고, 이러한 해에 맞추어서 분자를 돌려둔 후, 이동해 (Transaltion solution) 을 구해서 그 위치 (Orientation) 로 분자를 이동하였다. 이 때 R값은 53.9 % (8.0 - 3.5$\AA$) 이였고, 부분좌표 (Fractional coorcdinate) 에서는 0.102, 0.000, 0.261 이고, 직교좌표 (Orthogonal coorclinate) 에서는 4.616, 0.000, 13.167 의 결과를 얻었다.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.351-363
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• 2020

It is well known that alluvial sediment located in coastal region has been easily affected by geohazard like ground subsidence, marine or meteorological disasters which threaten invaluable lives and properties. The subsidence is a sinking of the ground due to underground material movement that mostly related to soil compaction by water extraction. Thus, continuous monitoring is essential to protect possible damage from the ground subsidence in the coastal region. Radar interferometric application has been widely used to estimate surface displacement from phase information of synthetic aperture radar (SAR). Thanks to advanced SAR technique like the Small BAseline Subset (SBAS), a time-series of surface displacement could be successfully calculated with a large amount of SAR observations (>20). Because the ALOS-2 PALSAR-2 L-band observations maintain higher coherence compared with other shorter wavelength like X- or C-band, it has been regarded as one of the best resources for Earth science. However, the number of ALOS-2 PALSAR-2 observations might be not enough for the SBAS application due to its global monitoring observation scenario. Unfortunately, the number of the ALOS-2 PALSAR-2 Stripmap images in area of our interest, Busan which located in the Southeastern Korea, is only 11 which is insufficient to apply the SBAS time-series analysis. Although it is common that the radar interferometry utilizes multiple SAR images collected from same acquisition mode, it has been reported that the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometric application could be possible under specific acquisition mode. In case that we can apply the Stripmap-ScanSAR interferometry with the other 18 ScanSAR observations over Busan, an enhanced time-series surface displacement with better temporal resolution could be estimated. In this study, we evaluated feasibility of the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometric application using Gamma software considering differences of chirp bandwidth and pulse repetition frequency (PRF) between two acquisition modes. In addition, we analyzed the interferograms with respect to spectral shift of radar carrier frequency and common band filtering. Even though it shows similar level of coherence regardless of spectral shift in the radar carrier frequency, we found periodic spectral noises in azimuth direction and significant degradation of coherence in azimuth direction after common band filtering. Therefore, the characteristics of spectral bandwidth in the range and azimuth direction should be considered cautiously for the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometry.

• Journal for History of Mathematics
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• v.20 no.4
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• pp.85-92
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• 2007

In this paper We study Some history and development of Geometry from the early 19th century to the late 20th century.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.5
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• pp.127-140
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• 2011

The research described in this report was conducted to find out how elements of the natural environment contributed to the formation of Chang'an, how its water system reinforced its status as the capital city, and what role it took for its urban function based on studies of the canal constructions. During the period of Sui and Tang, Chang'an built a sophisticated water system using Qu(渠), the irrigation facilities. In the water system, hills are called Yuan(原), and rivers with the proper environment to be developed plan into urban infrastructure facilities for irrigation water, urban living water, the composition of garden-based facility, reservoirs, and others. They improve agricultural productivity and, consequently, increase the city's competitiveness as well as contributing to the urban infrastructure, serving as a convenient source and ensuring the quality of life was abundant. So, the urban effects of the water system have raised the capital's status. With the contribution of its pragmatic water system, Chang'an not only performed its urban function brilliantly, but also established itself more firmly as a capital city.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.10-20
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• 2014

지금까지 대부분의 인공위성 또는 항공기 SAR 시스템은 하나의 위상 배열 안테나를 이용하며, 단 영상을 생성하고 판독하는데 주로 사용되었지만, 차세대 SAR 시스템은 다중 편파 관측이 가능하거나 이중 채널 또는 위상 배열 안테나의 분리 모드(split-antenna mode)를 통해 간섭기법의 적용이 가능한 시스템으로 발전이 이루어지고 있다. 이러한 측면에서 이 논문은 차세대 SAR 인공위성의 새로운 분석 기법 연구와 활용 증진을 위해, 유사한 기능을 보일 수 있는 이중 채널 항공기 SAR 시스템을 구축하고, 이로부터 단일 패스 간섭기법(single-pass interferometry)을 연구한 논문이다. 공간적으로 서로 다른 위치에 있는 두 개의 SAR 채널에서 동시에 수신된 레이다 신호를 간섭적으로 처리하여, 지형의 고도 정보를 추출하거나 이동하는 물체의 속도를 탐지할 수 있도록 알고리즘을 구현하였고, 새로운 활용 분야를 모색하고자 하였다.