• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.369-373
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• 2008

Special concern has been given to the elevated arsenic content in soils because of its high mobility and toxicity. Layered double hydroxide (LDH) which has a high anionic exchange capacity is another potential anion adsorbent for toxic anions such as arsenic, chromate and selenium etc. The uptake of arsenate from aqueous solutions by the calcined Mg-Al LDH has been investigated. The sorption capacity was about 530 mmol/kg. Sorption isotherm was defined as L-type in which arsenate was removed by LDH through anion uptake reaction. Arsenate sorption by the calcined Mg-Al LDH was occurred by reconstruction of LDH's framework. Competitive adsorption revealed that Mg-Al LDH had higher selectivity for arsenate than for sulfate. These results strongly suggest that calcined Mg-Al LDH has a promising potential for efficient removal of toxic metal oxides like arsenates from aqueous environments.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.33-38
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• 2003

This study is conducted to examine the data of climate or environmental change in the northeastern Asia during the last glacial maximum. A remarkable feature of the 18,000 BP biome reconstructions for China is the mid-latitude extention of steppe and desert biomes to the modem eastern coast. Terrestrial deposits of glacial maximum age from the northern part of Yellow Sea suggest that this region of the continental shelf was occupied by desert and steppe vegetation. And the shift from temperate forest to steppe and desert implies conditions very much drier than present in eastern Asia. Dry conditions might be explained by a strong winter monsoon and/or a weak summer monsoon. A very strong depression of winter temperatures at LGM. has in the center of continent has influenced in northeast Asia similarly. The vegetation of Hokkaido at LGM was subarctic thin forest distributed on the northern area of middle Honshu and cool and temperate mixed forest at southern area of middle Honshu in Japan. The vegetation landscape of mountain- and East coast region of Korea was composed of herbaceous plants with sparse arctic or subarctic trees. The climate of yellow sea surface and west region of Korea was much drier and temperate steppe landscape was extended broadly. It is supposed that a temperate desert appeared on the west coast area of Pyeongan-Do and Cheolla-Do of Korea. The reconstruction of year-round conditions much colder than today right across China, Korea and Japan is consistent with biome reconstruction at the LGM.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.132-142
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• 1998

In optical scanning holography, 3-D holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone plate. In this technique, the holographic information manifests itself as an electrical signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. This technique can be applied to 3-D optical remote sensing especially for identifying flying objects. In this paper, we first briefly review optical scanning holography and analyze the resolution achievable with the system. We then present mathematical expression of real and virtual image which are responsible for holographic image reconstruction by using Gaussian beam profile.

• Korean Journal of Construction Engineering and Management
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• v.9 no.6
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• pp.147-155
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• 2008

In the 1970s, increasing penetration of the housing co-housing policy, reconstruction be a great success to improve 1990‘s Old aged apartment's performance. However, in case of reconstruction, it causes the problem such as city environment destruction, resource waste, real-estate speculation etc. With the trend of sustainable construction and resource recycling, remodeling gets more attention than before. In case of country's remodeling, conventional method causes some problems such as delayed construction period and increased cost. Therefore, efforts that obtain economical efficiency are required to power remodeling through use of prefabrication method like PC technology that is useful for reduction effect of construction period, cost and site labor and excellent quality. This research indicates reduceing factor for facilitating prefabrication method and technology selecting framework through specific of Expanding Floor method and remodeling cases to increase the efficiency of remodeling, considers construction parties approaching plan for prefabrication as occasion that powers remodeling.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.211-222
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• 2004

Lately construction industry tends to prefer remodeling of existing buildings rather than new construction or reconstruction of buildings due to strengthening of several restriction related to real estates along with prolonged depression. And also, remodeling of building costs less and creates less wastes compared to reconstruction and so it is more profitable in financial and environmental view. However remodeling is process of creating new environment with existing building. Therefor remodeling must follow the procedure realizing problem and fix the problem based on through investigation on existing building and users requirement must be faithfully reflected. Specially in case of apartment houses, since vagueness on ownership and management authority on common parts exists. Hereupon, in this study we are to present the procedure of analyzing apartment house remodeling method through user requirement by approaching to several considerable factors in user request side.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.885-890
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• 2008

Until now, the domestic construction market has been formed focusing on new construction and reconstruction in the apartment industry. Recently, however, the remodeling market for old structures have shown a tendency towards land shortage and land price increases in the major cities: the reinforcement of regulations regarding reconstruction; expenditure reduction and the solving of environmental problems by regarding old structures is pursuing low costs and maximum efficiency. The interest in remodeling is increasing, however, remodeling has not been successfully initiated in the apartment division for a reasonable period of time. Consequently to acquire mutual agreement for remodeling from the residential occupants. In order to evaluate profitability, it is necessary to set priorities and reasonable criteria for remodelling and to this end, it is also required to assess each fact of remodelling in view of both customers and supplied. Thus, a sample apartment housing complex was analyzed for geographic location, surrounding environment floor area ratio, site area, number of households, number of stories and unit area and thereupon, its remodelling profitability was analyzed to select an effective remodeling method as an alternative case for apartment house owners and remodelling.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.35-44
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• 2007

Since the omnidirectional camera system with a very large field of view could take many information about environment scene from few images, various researches for calibration and 3D reconstruction using omnidirectional image have been presented actively. Most of line segments of man-made objects we projected to the contours by using the omnidirectional camera model. Therefore, the corresponding contours among images sequences would be useful for computing the camera transformations including rotation and translation. This paper presents a novel two step minimization method to estimate the extrinsic parameters of the camera from the corresponding contours. In the first step, coarse camera parameters are estimated by minimizing an angular error function between epipolar planes and back-projected vectors from each corresponding point. Then we can compute the final parameters minimizing a distance error of the projected contours and the actual contours. Simulation results on the synthetic and real images demonstrated that our algorithm can achieve precise contour matching and camera motion estimation.

• Journal of radiological science and technology
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• v.43 no.2
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• pp.79-85
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• 2020

The influence of metal artifact in CT image depends on the type of metal materialsm, the reconstruction algorithm, and scan parameters. The presence of metal artifacts was quantitatively evaluated by applying the standard and MAR algorithms through the phantom study. In the change of tube voltage applied the standard algorithm, metal artifact decreased to 44.9% for 80 vs 120 kVp, 24% for 100 vs 120 kVp, while the image taken at 140 kVp increased the artifact by 19% compared to 120 kVp. When the tube current was increased from 100 to 300 mA, there was no significant difference in the CT value and noise. Black band and white strike artifacts occurred up to 65.9% in the adjacent ROI of the metal driver, whereas titanium screw produced lesser metal artifact than that of the metal driver. The combination of 120kVp or higher tube voltage-standard algorithm was effective in removing black band artifacts as well as white streak by high density materials. However, MAR reconstruction algorithm was useful in improving image quality under the environment of low kVp and high density materials, without increase of radiation exposure.

• Korean Journal of Remote Sensing
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• v.15 no.3
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• pp.167-175
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• 1999

So far, the remote sensing technology has widely been used in a variety of application areas such as military, medical imaging, environment, geology and so forth. The microwave remote sensing uses the wavelengths ranging from around one centimeter up to a few tens of centimeters and is known to be very effective regardless of the weather conditions and the day/night time as compared with the reflective InfraRed (IR) remote sensing or the thermal IR remote sensing. There are three generic modes of synthetic aperture radar imaging systems depending on its application, that is, stripmap mode, spotlight mode, or inverse mode. In this article we focus on the issue of imaging of flying aircrafts for the inverse mode of a ground - based, fixed radar with moving objects. The imaging of flying aircrafts is considered to be an important step for the automatic target recognition systems, and therefore a great deal of efforts have recently been made on the subject. Here we review the three representative methods including the Fourier transform processing, the time - frequency processing, and the reconstruction from the projection. Some relative merits and drawbacks are also discussed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.1
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• pp.34-42
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• 2019

Objectives: Various bone graft substitute materials are used to enhance bone regeneration in the maxillofacial skeleton. In the recent past, synthetic graft materials have been produced using various synthetic and natural calcium precursors. Very recently, eggshell-derived hydroxyapatite (EHA) has been evaluated as a synthetic bone graft substitute. To assess bone regeneration using EHA in cystic and/or apicectomy defects of the jaws through clinical and radiographic evaluations. Materials and Methods: A total of 20 patients were enrolled in the study protocol (CTRI/2014/12/005340) and were followed up at 4, 8, 12, and 24 weeks to assess the amount of osseous fill through digital radiographs/cone-beam computed tomography along with clinical parameters and complications. Wilcoxon matched pairs test, means, percentages and standard deviations were used for the statistical analysis. Results: The sizes of the lesions in the study ranged from 1 to 4 cm and involved one to four teeth. The study showed significant changes in the formation of bone, the merging of material and the surgical site margins from the first week to the first month in all patients (age range, 15-50 years) irrespective of the size of the lesions and the number of teeth involved. Bone formation was statistically significant from the fourth to the eighth week, and the trabecular pattern was observed by the end of 12 weeks with uneventful wound healing. Conclusion: EHA showed enhancement of bone regeneration, and healing was complete by the end of 12 weeks with a trabecular pattern in all patients irrespective of the size of the lesion involved. The study showed enhancement of bone regeneration in the early bone formative stage within 12 weeks after grafting. EHA is cost effective and production is environment friendly with no disease transfer risks. Thus, natural bioceramics will play an important role in the reduction of costs involved in grafting and reconstruction.