• Conservation Science in Museum
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• v.7
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• pp.33-42
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• 2006

The Conservation Science Laboratory of the National Museum of Korea had drawn up the list of conservation treatment priority according to the artifact status in the collection and performed conservation treatment based on the priority list since 2006. This paper introduces the restoration process of the lost part of a black teacup(Sindo 1961) with newly developed restoration material. Part of the peeled off glaze was analyzed with LIBS and SEM-EDS analyser to find out the glaze ingredients that make the unique pattern of black teacup.

• Journal of Conservation Science
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• v.22
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• pp.61-76
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• 2008

We examined characterizations of Paraloid B72 films when it dissolved in four different solvents-acetone, MEK, toluene and xylene. The surface before and after coating were observed by optical microscope and AFM. Thickness and contact angle of films was measured and surface energy was calculated for grasping properties of films. We also tested adhesive strength of films by scratch tester and durability of films by performing yellowing test. The result was that xylene has better coating property than other solvents. Because 10% Paraloid B72 in xylene film is even, non-mottled, thin, stabilized in yellowish and has proper hydrophobic, we confirmed xylene is good solvent for bronze artifact conservation. However, other tests will need for finding appropriate concentration of Paraloid B72.

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.73-80
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• 2015

The Yang-gyeong-gyu-il-ui (兩景揆日儀) is a kind of elevation sundial using three wooden plates. Sang-hyeok Lee (李尙爀, 1810~?) and Byeong-cheol Nam (南秉哲, 1817~1863) gave descriptions of this sundial and explained how to use it in their Gyu-il-go (揆日考) and Ui-gi-jip-seol (儀器輯說), respectively. According to Gyu-il-go (揆日考) there are two horizontal plates and two vertical plates that have lines of season and time. Subseasonal (節候) lines are engraved between seasonal (節氣) lines, subdividing the interval into three equal lines of Cho-hu (初候, early subseason), Jung-hu (中候, mid subseason) and Mal-hu (末候, late subseason); there are 13 seasonal lines for a year, thus resulting in 37 subseasonal lines; also, there are 12 double-hour (時辰) lines for a day engraved on these plates. The only remaining artifact of Yang-gyeong-gyu-il-ui was made in 1849 (the $15^{th}$ year of Heon-jong) and is kept at the Korea University Museum. We have compared and analyzed Yang-gyeong-gyu-il-ui and similar western sundials. Also, we have reviewed the scientific aspect of this artifact and built a replica. Yang-gyeong-gyu-il-ui is a new model enhanced from the miniaturization development in the early Joseon Dynasty and can be applied to the southern part of the tropic line through a structure change.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.401-406
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• 2012

When viewed using a magnetic resonance imaging (MRI) system, invasive materials inside the human body, in many cases, severely distort the MR image of human tissues. The degree of the MR image distortion increases in proportion not only to the difference in the susceptibility between the invasive material and the human tissue, but also to the intensity of the magnetic field induced by the MRI system. In this study, by blending paramagnetic Ti particles with diamagnetic graphite, we synthesized $Ti_{100-x}C_x$ composites that can reduce the artifact in the MR image under the high-strength magnetic field. Of the developed composites, $Ti_{70}C_{30}$ showed the magnetic susceptibility of ${\chi}=67.6{\times}10^{-6}$, which corresponds to 30% of those of commercially available Ti alloys, the lowest reported in the literature. The level of the MR image distortion in the vicinity of the $Ti_{70}C_{30}$ composite insert was nearly negligible even under the high magnetic field of 4.7 T. In this paper, we reported on a methodology of designing new structural materials for bio-applications, their synthesis, experimental confirmation and measurement of MR images.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.306-307
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• 2008

본 논문에서는 제한적인 자원이 할당된 모바일 환경에서 블록기반의 압축방식을 사용하여 영상을 복원할 때에 나타나는 블록화 연상을 제거하기 위해 효율적인 실시간 후처리 기법을 제안한다. 제안하는 후처리 기법은 영상에 존재하는 블록화 현상으로 인해 나타나는 다양한 인공물에 대해 디블록킹 필터링와 방향성 필터링를 적용하여 효율적으로 블록화 현상을 제거한다. 후처리 과정 중 영상에 존재하는 고유의 고주파 성분과 인공물로 인한 고주파 성분을 구분하여, 필더링 과정으로 고유의 고주파 성분이 함께 제거되지 않도록 보호해준다. 다양한 영상을 통해 본 논문에서 제안한 후처리 기법과 기존에 알려진 후처리 기법들을 비교하는 실험을 하였고, 도출된 실험 결과를 객관적인 지표로 제시하여 제안하는 기법의 우수함을 입증하였다.

• Research in Mathematical Education
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• v.16 no.1
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• pp.1-13
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• 2012

This paper explores gifted students' reasoning abilities. Three tests were developed in order to assess and analyze their reasoning abilities building on previous research on covariational reasoning. Giving consideration to the arising problems in the tests, we constructed a LOGO-based JavaMAL microworld environment which engages students in an active learning environment. This environment was designed by applying 'instrumental approach' in microworld. Based upon the post test results, the role of activity in microworld environment as 'instrument mediated activity' is also discussed.

• International Journal of Control, Automation, and Systems
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• v.5 no.6
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• pp.701-706
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• 2007

The measurement accuracy for heart rate or $SpO_2$ using photoplethysmography (PPG) is influenced by how well the noise from motion artifacts and other sources can be removed. Eliminating the motion artifacts is particularly difficult since its frequency band overlaps that of the basic PPG signal. Therefore, we propose the Periodic Moving Average Filter (PMAF) to remove motion artifacts. The PMAF is based on the quasi-periodicity of the PPG signals. After segmenting the PPG signal on periodic boundaries, we average the $m^{th}$ samples of each period. As a result, we remove the motion artifacts well without the deterioration of the characteristic point.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.2
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• pp.97-101
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• 2013

Bit-depth expansion is a process of enhancing the image quality by increasing the number of intensity levels. To solve this problem, a hybrid method is proposed, where the pixels are categorized into smooth and complex regions, and are processed using different methods. The pixels in the smooth region are reconstructed with a smooth prior, and a Bayesian estimator is used for the pixels in the complex region. The proposed method effectively removes the false contour artifacts while requiring less computation than conventional methods. In addition, the method shows good quantitative performance, and the PSNR gains over the best existing method are 1.45 dB and 0.26 dB for 4 bits and 3 bits expansion cases, respectively.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.126-126
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• 2002

Purpose： For quantitative analysis of the cardiac diseases, it is necessary to segment the left-ventricle(LV) in MR cardiac images. Snake or active contour model has been used to segment LV boundary. In using these models, however, the contour of the LV may not converge to the desirable one because the contour may fall into local minimum value due to image artifact in inner region of the LV Therefore, in this paper, we propose the new preprocessing method using K-means clustering and merging algorithms that can improve the performance of the active contour model.

• Archives of Pharmacal Research
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• v.24 no.6
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• pp.522-523
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• 2001

A new naphthoquinone, 5,8-dihydro-2,7-dimethyl-[1,4]naphthoquinone (1), which was named 5,8-dihysrochimaphilin, isolated from an ethyl acetate soluble fraction from the root of Pyrola japonica, together with chimaphilin (2). Compound 1 was transformed rapidly to 2 upon exposure to air by HPLC analysis. This fact supported that chimaphilin (2) may be an artifact from 1 .