• The Journal of the Petrological Society of Korea
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• v.10 no.3
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• pp.179-189
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• 2001

The determination of trace concentration of U, Th and Pb was carried out for chemical dating of zircon and monazite by electron microprobe. Detection limit and error range should be considered to measure characteristic X-rays of M-line from those minerals, which are low in the ionization of atom and low peak intensity in the spectrum. The element of U, Th and Pb were simultaneously measured with 3 spectrometers equipped with PET crystal to reduce a total counting time and error due to drift of instrumental operating condition. Detection limit could be improved from increase of the peak/background ratio through adjusting pulse height analyzer about 1000 mv baseline. Under permissible maximum analytical conditions, theoretical detection limit of U, Th and Pb is down to 30 ppm (99% confidence level). The analytical result was maintained at a relative error $\pm$10% ($2{\sigma}$) in 800 ppm Pb, $\pm$5% ($2{\sigma}$) in 2330 ppm U and $\pm$10% ($2{\sigma}$) in dating from a single measurement of zircon at 15 keV and 100 nA. However, for the precise dating of zircon and monazite, if it is considered a 3 $\mu\textrm{m}$ spatial resolution, <100 ppm ($3{\sigma}$) detection limit and <$\pm$10% ($2{\sigma}$) relative error, optimum analytical conditions are given as 15~20 keV accelerating voltage, 100~200 nA beam current and 300~1200 sec total counting time. To reduce material damage by high current, there is need to be up to 3~5 $\mu\textrm{m}$ of electron beam diameter, or to use arithmetic average of multiple measuring at a shorter counting time. A younger or relatively low concentration rocks can be dated chemically by lower detection limit and improved precision resulted from increase of current and measuring time.

• Korean Journal of Remote Sensing
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• v.36 no.5_2
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• pp.989-1006
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• 2020

Building change monitoring based on building detection is one of the most important fields in terms of monitoring artificial structures using high-resolution multi-temporal images such as CAS500-1 and 2, which are scheduled to be launched. However, not only the various shapes and sizes of buildings located on the surface of the Earth, but also the shadows or trees around them make it difficult to detect the buildings accurately. Also, a large number of misdetection are caused by relief displacement according to the azimuth and elevation angles of the platform. In this study, object-based building detection was performed using the azimuth angle of the Sun and the corresponding main direction of shadows to improve the results of building change detection. After that, the platform's azimuth and elevation angles were used to detect changed buildings. The object-based segmentation was performed on a high-resolution imagery, and then shadow objects were classified through the shadow intensity, and feature information such as rectangular fit, Gray-Level Co-occurrence Matrix (GLCM) homogeneity and area of each object were calculated for building candidate detection. Then, the final buildings were detected using the direction and distance relationship between the center of building candidate object and its shadow according to the azimuth angle of the Sun. A total of three methods were proposed for the building change detection between building objects detected in each image: simple overlay between objects, comparison of the object sizes according to the elevation angle of the platform, and consideration of direction between objects according to the azimuth angle of the platform. In this study, residential area was selected as study area using high-resolution imagery acquired from KOMPSAT-3 and Unmanned Aerial Vehicle (UAV). Experimental results have shown that F1-scores of building detection results detected using feature information were 0.488 and 0.696 respectively in KOMPSAT-3 image and UAV image, whereas F1-scores of building detection results considering shadows were 0.876 and 0.867, respectively, indicating that the accuracy of building detection method considering shadows is higher. Also among the three proposed building change detection methods, the F1-score of the consideration of direction between objects according to the azimuth angles was the highest at 0.891.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.471-479
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• 2011

The velocity horizontal response spectra using the observed ground motions from the recent 5 macro earthquakes, equal to or larger than 4.8 in magnitude, around Korean Peninsula were analysed and then were compared to the acceleration horizontal response spectra, seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and finally the Korean Standard Design Response Spectrum for general structures and buildings. 102 velocity horizontal ground motions, including NS and EW components, were used for velocity horizontal response spectra and then normalized with respect to the peak velocity value of each ground motion. First, the results showed that velocity horizontal response spectra have larger values at the range of medium natural period, but acceleration horizontal response spectra have larger values at the range of short natural periods. Secondly, the results also showed that velocity horizontal response spectra exceed Reg. Guide 1.60 for longer natural periods bands less than 6-7 Hz. Finally, the results were also compared to the Korean Standard Response Spectrum for the 3 different soil types(SC, SD, and SE soil type) and showed that velocity horizontal response spectra revealed much higher values for the frequency bands below 1.5(SC), 2.0(SD), and 3.0(SE) seconds, respectively, than the Korean Standard Response Spectrum. The results suggest that the fact that acceleration, velocity, and displacement horizontal response spectra have larger values at the range of short, medium, and long natural periods, respectively, can be applied consistently to those form domestic ground motion, especially, the velocity ground motion. Information on response spectrum at such medium range periods can be very important since the domestic design of buildings and structures emphasizes recently medium and long natural periods than short one due to increased super high-rise buildings.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.109-123
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• 2009

The aim of the study was to assess the influence of insertion torque of bone quality and to compare axial force, moment and von Mises stress using finite element analysis of plastoelastic property for bone stress and strain by dividing bone quality to its thickness of cortical bone, density of trabecular bone and existence of lower cortical bone when implant inserted to mandibular premolar region. The $Br{\aa}nemark$ MKIII. RP implant and cylindrical bone finite model were designed as cortical bone at upper border and trabecular bone below the cortical bone. 7 models were made according to thickness of cortical bone, density of trabecular bone and bicortical anchorage and von Mises stress, axial force and moment were compared by running time. Dividing the insertion time, it seemed 300msec that inferior border of implant flange impinged the upper border of bone, 550msec that implant flange placed in middle of upper border and 800msec that superior border of implant flange was at the same level as bone surface. The maximum axial force peak was at about 500msec, and maximum moment peak was at about 800msec. The correlation of von Mises stress distribution was seen at both peak level. The following findings were appeared by the study which compared the axial force by its each area. The axial force was measured highest when $Br{\aa}nemark$ MKIII implant flange inserts the cortical bone. And maximal moment was measured highest after axial force suddenly decreased when the flange impinged at upper border and the concentration of von Mises stress distribution was at the same site. When implant was placed, the axial force and moment was measured high as the cortical bone got thicker and the force concentrated at the cortical bone site. The influence of density in trabecular bone to axial force was less when cortical bone was 1.5 mm thick but it might be more affected when the thickness was 0.5 mm. The total axial force with bicortical anchorage, was similar when upper border thickness was the same. But at the lower border the axial force of bicortical model was higher than that of monocortical model. Within the limitation of this FEA study, the insertion torque was most affected by the thickness of cortical bone when it was placed the $Br{\aa}nemark$ MKIII implant in premolar region of mandible.

• Conservation Science in Museum
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• v.19
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• pp.1-18
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• 2018

The Stele for National Preceptor Hongbeop from the Jeongtosa Temple site in Chungju is one of the most important stone cultural heritage items for exemplifying the style of the Goryeo era. Despite its obvious value, this relic has been stored in a weathered condition at the National Museum of Korea. It had suffered various dismantling and displacements during the Japanese colonial period and had long been exposed in the open air. The stele was selected as a subject for the Stone Monuments Restoration Project launched by the National Museum of Korea in 2015. In preparation for its outdoor exhibition as part of the restoration project, this study investigated the characteristics of its materials, produced a map of its deterioration from weathering, and carried out ultrasonic analysis of the materials to provide findings useful for conservation treatment. The materials analysis revealed that the turtle-shaped pedestal of the stele was made from two-mica granite consisting of medium-grained quartz, plagioclase, alkali feldspar, biotite, and muscovite. Its body stone is crystalline marble, the rock-forming mineral in which is medium-grained calcite in a rose-pink color with dark grey spots. The dragon top of the stele is made of crystalline marble, the major component of which is medium-grained calcite of a light-grey color. The deterioration consists of 21.5% abrasion on the stone body, with its south face most damaged, and 18.6% granular disintegration, with the north face most damaged. The ultrasonic material characterization conducted for mapping the general condition of weathering shows low values on the parts-assembly area of the turtle-shaped pedestal and on the upper portion of the stone body. It is considered that there is dislocation due to partial blistering and fracturing as well as to the differences in surface treatment. Prior to the outdoor exhibition of the stele, the surface was cleaned of contaminants and was consolidated based on the scientific investigation in order to prevent weathering from the external environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.226-226
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• 2008

지난 10여년 동안 Sn-3.0Ag-0.5(wt%)Cu 합금은 대표 무연솔더 조성으로 다양한 전자제품의 실장 및 접합에 적용되어 왔으며, 그 신뢰성 역시 충분히 검증된 바 있다. 그러나 최근 Ag 가격의 급격한 상승과 솔더 접합부의 내 충격 신뢰성을 보다 향상시키고자 하는 업계의 동향은 Ag의 함량이 낮은 무연솔더 조성의 적용 확대를 유도하고 있다. 이에 따라 본 연구자들은 저 Ag 함유 무연슬더로 Sn-1.2Ag-0.5Cu-0.4In 조성을 제안한 바 있는데, 이는 Sn-3.0Ag-0.5Cu 조성 이상의 solderability를 가지면서도 그 금속원료 가격이 약 20% 가량 저렴한 특징을 가진다. 또한 열 싸이클링 (cycling) 테스트를 통한 슬더 조인트의 신뢰성을 평가한 결과, Sn-3.0Ag-0.5Cu에 크게 뒤떨어지지 않는 양호한 특성이 관찰되었다. 따라서 본 연구에서는 열 싸이클링 테스트와 더불어 최근 그 중요성이 지속적으로 커지고 있는 내 충격 신뢰성 평가 시험을 실시하여 개발된 4원계 무연솔더 조성의 기계적 특성을 기존 무연솔더 조성과 비교, 분석해 보았다. 각 솔더 조성은 솔더 볼 형태로 제조되어 CSP(Chip Scale Package) 상에 범핑 (bumping)되었으며, CSP를 PCB(Printed Circuit Board) 상에 실장하는 공정에서도 Sn-3.0Ag-0.5Cu 및 Sn-1.2Ag-0.5Cu-0.4In의 두 종류의 솔더 페이스트가 사용되었다. 본 연구에서의 내 충격 신뢰성 시험에는 자체 제작한 rod drop 시험기를 사용하였는데, 고정된 CSP 실장 board의 후면 부위를 일정한 높이에서 추를 반복적으로 자유 낙하시켜 급격한 충격을 주는 방식으로 실험을 실시하였다. 이 때 추의 무게는 30g, 낙하 높이는 10cm 였으며, 추의 낙하 시 측정된 board 의 휨 변위량은 약 0.7mm로 측정되었다. 사용된 CSP와 PCB 는 모두 daisy chain 방식으로 연결되어 있기 때문에 저항측정기를 사용한 간단한 실시간 저항 측정 방법으로 시험 이력에 따른 파단부의 발생 시점과 대략의 위치를 손쉽게 확인할 수 있었다. 솔더 조인트의 파단 기준 저항값으로 $1000\Omega$을 설정하였으며. 각 조건 당 5 개 이상의 샘플에 대해 평가를 실시한 후 그 평균값을 조사하였다. 시험 결과 제안된 Sn-1.2Ag-0.5Cu-0.4In 조성은 대표적인 저 Ag 함유 조성인 Sn-1.0Ag-0.5Cu에 비해서는 떨어지는 내 충격 신뢰성을 나타내었지만, 우수한 연성에 기인하여 Sn-3.0Ag-0.5Cu 조성에 비해서는 약 2 배 이상 우수한 신뢰성이 관찰되었다. 또한 CSP의 실장 시 Sn-3.0Ag-0.5Cu보다 Sn-1.2Ag-0.5Cu-0.4In 조성 솔더 페이스트를 적용한 경우에서 보다 우수한 내 충격 신뢰성을 나타내어 기본적으로 개발된 Sn-1.2Ag-0.5Cu-0.4In 솔더 페이스트가 Sn-3.0Ag-0.5Cu 조성의 기존 솔더 페이스트 보다 내 충격 신뢰성이 우수함을 검증할 수 있었다. 각 조성의 솔더 조인트를 $150^{\circ}C$ 에서 500시간 aging한 후 실시한 내 충격 신뢰성 평가에서는 모든 조성에서 그 신뢰성이 급감하는 경항을 나타내었으나, Sn-1.2Ag-0.5Cu-0.4In가 Sn-l.0Ag-0.5Cu보다도 그 상대적인 신뢰성이 우수한 것으로 관찰되었다. 이와 같이 aging 후 실시하는 충격시험은 가장 실제적인 상황과 유사한 조건이므로 상기의 실험 결과는 매우 고무적이었으며, 이에 대한 보다 면밀한 분석이 요청되었다. 마지막으로 파면 및 미세조직 관찰을 통하여 각 조성에서의 충격 파단 특성을 비교, 분석해 보았다.

• Journal of Digital Contents Society
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• v.13 no.2
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• pp.225-233
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• 2012

The 3D stereoscopic image contents have been emerging as the blue chip of the contents market of the next generation since the . However, all the 3D contents created commercially in the country have failed to enter box office. It is because the quality of Korean 3D contents is much lower than that of overseas contents and also current 3D post production process is based on 2D. Considering all these facts, the 3D editing process has connection with the quality of contents. The current 3D editing processes of the production case of are using the way that edits with the system on basis of 2D, followed by checking with 3D display system and modifying, if there are any problems. In order to improve those conditions, I suggest that the 3D editing process contain more objectivity by visualizing the depth data applied in some composition work such as Disparity map, Depth map, and the current 3D editing process. The proposed process has been used in the music drama , comparing with those of the film . The 3D values could be checked among cuts which have been changed a lot since those of , while the 3D value of drew an equal result in general. Since the current process is based on an artist's subjective sense of 3D, it could be changed according to the condition and state of the artist. Furthermore, it is impossible for us to predict the positive range, so it is apprehended that the cubic effect of space might be perverted by showing each different 3D value according to cuts in the same space or a limited space. On the other hand, the objective 3D editing by applying the visualization of depth data can adjust itself to the cubic effect of the same space and the whole content equally, which will enrich the 3D contents. It will even be able to solve some problems such as distortion of cubic effect and visual fatigue, etc.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.1
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• pp.1-7
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• 2016

Purpose: The aim of this study was to evaluate the effect of increased vertical dimension of occlusion on lower facial changes by facial type. Materials and methods: Lateral cephalograms from 261 patients were obtained and classified by sagittal (Class I, II, and III) and vertical (hypodivergent, normodivergent, and hyperdivergent) facial patterns. Retrusive displacement of soft tissue Pogonion and downward displacement of soft tissue Menton were measured in each group after 2 mm of vertical dimension of occlusion was increased at the lower central incisor using a virtual simulation program. The ratio of both displacements was calculated in all groups. The statistical analysis was done by 2-way ANOVA and Post hoc was done by Tukey test (5% level of significance). Results: Retrusive displacement of soft tissue Pogonion in Class III group was statistically different compared to Class I and II, and in vertical facial groups all 3 groups were significantly different (P<.05). Downward displacement of soft tissue Menton showed statistically significant difference between all sagittal groups and vertical groups (P<.05). The ratio of both displacements showed statistically significant difference in all sagittal groups and vertical groups (P<.05), and Class II hyperdivergent group had the highest value. Conclusion: Lower facial change was statically significant according to the facial type when vertical dimension of occlusion increased. Class II hyperdivergent facial type showed the highest ratio after increase in vertical dimension of occlusion.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.761-769
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• 2014

Ultra high performance concrete (UHPC) has been developed to overcome the low strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.2
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• pp.135-145
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• 2020

Wave observation is widely used to direct observation method for observing the water surface elevation using wave buoy or pressure gauge and remote-sensing wave observation method. The wave buoy and pressure gauge can produce high-quality wave data but have disadvantages of the high risk of damage and loss of the instrument, and high maintenance cost in the offshore area. On the other hand, remote observation method such as radar is easy to maintain by installing the equipment on the land, but the accuracy is somewhat lower than the direct observation method. This study investigates the data quality of MIROS Wave and Current Radar (MWR) installed at Dokdo and improve the data quality of remote wave observation data using the wave buoy (CWB) observation data operated by the Korea Meteorological Administration. We applied and developed the three types of wave data quality control; 1) the combined use (Optimal Filter) of the filter designed by MIROS (Reduce Noise Frequency, Phillips Check, Energy Level Check), 2) Spike Test Algorithm (Spike Test) developed by OOI (Ocean Observatories Initiative) and 3) a new filter (H-Ts QC) using the significant wave height-period relationship. As a result, the wave observation data of MWR using three quality control have some reliability about the significant wave height. On the other hand, there are still some errors in the significant wave period, so improvements are required. Also, since the wave observation data of MWR is different somewhat from the CWB data in high waves of over 3 m, further research such as collection and analysis of long-term remote wave observation data and filter development is necessary.