• Journal of Astronomy and Space Sciences
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• 제16권2호
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• pp.159-166
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• 1999

As the spatial resolution of remote sensing satellites becomes higher, very accurate determination of the position of a LEO (Low Earth Orbit) satellite is demanding more than ever. Non-symmetric Earth gravity is the major perturbation force to LEO satellites. Since the orbit propagation is performed in the celestial frame while Earth gravity is defined in the terrestrial frame, it is required to convert the coordinates of the satellite from one to the other accurately. Unless the coordinate conversion between the two frames is performed accurately the orbit propagation calculates incorrect Earth gravitational force at a specific time instant, and hence, causes errors in orbit prediction. The coordinate conversion between the two frames involves precession, nutation, Earth rotation and polar motion. Among these factors, unpredictability and uncertainty of Earth rotation, called UTI-UTC, is the largest error source. In this paper, the effect of UTI-UTC on the accuracy of the LEO propagation is introduced, tested and analzed. Considering the maximum unpredictability of UTI-UTC, 0.9 seconds, the meaningful order of non-spherical Earth harmonic functions is derived.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.396-400
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• 2003

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design condidering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verifiedthe test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective method in thermal-appropriate design..

• Natural Product Sciences
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• 제26권2호
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• pp.171-175
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• 2020

Liriodendron tulipifera, belonging to the family Magnoliaceae, is commonly called tulip tree. Four N-acetylated aporphine alkaloids, N-acetylnornuciferine (1), N-acetylanonaine (2), N-acetyl-3-methoxynornuciferine (3), and N-acetyl-3-methoxynornantenine (4) were isolated from the roots of L. tulipifera. Although the purity of each compound (1 - 4) was determined to be 97, 96, 99, and 98%, respectively, the ¹H and ¹³C NMR spectroscopic data of the aporphine alkaloids 1 - 4 displayed all signals in duplicate, indicating the presence of two rotamers due to restricted rotation of N-COCH₃ functionality in solution status. The absolute configurations of 1 - 4 w ere established by measuring specific rotation and comparison with the reported data. This is the first report on the ¹H and ¹³C NMR assignments of N-acetyl-3-methoxynornuciferine (3) and N-acetyl-3-methoxynornantenine (4). This study provides advanced NMR spectroscopic data for the structure determination of rotameric aporphine alkaloids.

• 한국지반신소재학회논문집
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• 제8권1호
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• pp.41-51
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• 2009

본 논문은 지반 적용을 위한 사면붕괴 억제 타이백 벽체설계의 주제에 관한 여러 가지 설계고려사항을 검토해보았다. 설계는 특정 지역 조건에 맞는 벽체를 설계하기 위한 토질역학과 지질학의 복합된 지식을 요구한다. 설계를 완성하기 위한 많은 측면들이 여전히 완벽하게 연구되어 있지 않다. 본 논문은 기존의 타이백 벽체설계에 관한 개요와 suppressor 벽체 지중압력/타이백에 기인한 응력 회전과 같은 새로운 이슈의 토론 등을 기술하였다. 지진력의 효과에 관해서도 서술하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.498-503
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design considering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective mettled in thermal-appropriate design.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.869-872
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• 2000

Although many content-based image retrieval systems using shape feature have tried to cover rotation-, position- and scale-invariance between images, there have been problems to cover three kinds of variance at the same time. In this paper, we introduce new approach to extract shape feature from image using MBR(Minimum Bounding Rectangle). The proposed method scans image for extracting MBR information and, based on MBR information, compute contour information that consists of 16 points. The extracted information is converted to specific values by normalization and rotation. The proposed method can cover three kinds of invariance at the same time. We implemented our method and carried out experiments. We constructed R*_tree indexing structure, perform k-nearest neighbor search from query image, and demonstrate the capability and usefulness of our method.

• 한국전문물리치료학회지
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• 제15권1호
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• pp.61-68
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• 2008

The aim of the study was to evaluate the effect of a disease-specific exercise (DSE) on temporomandibular joint (TMJ) function and neck mobility in TMJ dysfunction associated with ankylosing spondylitis (AS). Ten AS patients (seven males and three females) with TMJ dysfunction were recruited for this study. The DSE included exercises to correct head and neck posture and to improve the flexibility of the neck and TMJs. The patients attended treatment three times a week for 4 weeks, averaging 1 hour each session. Assessments were performed pretreatment, posttreatment, and 6 weeks after the completion of treatment. General physical status was assessed by four clinical measures (tragus-to-wall distance, modified Schober test, lumbar side flexion, and intermalleolar distance), the Bath ankylosing spondylitis function index (BASFI), and the Bath ankylosing spondylitis disease activity index. The main outcome measures included TMJ function (craniomandibular index (CMI)), and neck mobility (flexion, extension, rotation, and lateral rotation). None of the measures of general physical status, with the exception of BASFI, were significant1y different between the pretreatment, posttreatment, and 6-week follow-up (p>.05). However, CMI and all neck movements, except for extension, significant1y improved after the treatment (p<.05). These improvements were maintained during the follow-up period. The DSE used in the present study seems to be a clinical1y useful method for managing patients with symptoms from the stomatognathic system in AS. Further studies with more subjects and longer treatment times, including the follow-up period, will be conducted to validate these findings.

• 한국토양비료학회지
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• 제46권2호
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• pp.81-86
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• 2013

For organic farming, green manure crops such as leguminous forages and barley have been broadly used to improve soil fertility and soil physical and chemical properties by repeatedly cutting and mulching them directly as winter crop in the field in the rotation. In this investigation we selected 78 agricultural farm corporations as well as individual organic farmhouses related to crop rotation from greenmanure crops to main crops in order to analyze the relationship of cropping system between main crops and green manure crops. The results showed that the green manure crops were divided into two groups as leguminous and nonleguminous crops, representing that those are limited to specific climate and farming systems of regions. Also the 10 or less green manure crops including sudangrass, hairyvetch, italian ryegrass, sorghun, buckwheat, oat, pea, rye, clover, and canola which belong to leguminous crops which are presently cultivated from the organic farmhouses within the rotational crop system. We also confirmed that the major main crops are sweet potato, soybean, corn, tobacco, spinach from usage frequency analyzed by NetMiner H 2.6 which was used to estimate the rotational cropping system among the green manure crops and main crops.

• 한국분말재료학회지
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• 제30권2호
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• pp.146-155
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• 2023

The Ti-6Al-4V lattice structure is widely used in the aerospace industry owing to its high specific strength, specific stiffness, and energy absorption. The quality, performance, and surface roughness of the additively manufactured parts are significantly dependent on various process parameters. Therefore, it is important to study process parameter optimization for relative density and surface roughness control. Here, the part density and surface roughness are examined according to the hatching space, laser power, and scan rotation during laser-powder bed fusion (LPBF), and the optimal process parameters for LPBF are investigated. It has high density and low surface roughness in the specific process parameter ranges of hatching space (0.06-0.12 mm), laser power (225-325 W), and scan rotation (15°). In addition, to investigate the compressive behavior of the lattice structure, a finite element analysis is performed based on the homogenization method. Finite element analysis using the homogenization method indicates that the number of elements decreases from 437,710 to 27 and the analysis time decreases from 3,360 to 9 s. In addition, to verify the reliability of this method, stress-strain data from the compression test and analysis are compared.

• The Journal of Korean Physical Therapy
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• 제22권3호
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• pp.1-8
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• 2010

Purpose: The main causes of chronic neck pain (CNP) are wrong postures and degenerative changes. This study investigated the effects of specific exercise on elderly women with CNP. Methods: 29 elderly women who complain of CNP were classified into experimental group (14) and control group (15). The experimental group was treated with specific exercise and minimal conventional therapy, whereas the control group was treated only with conventional therapy. Then the effects on the visual analogue scale (VAS), neck disability index (NDI), self-rating anxiety scale (SAS), Korean form of geriatric depression scale (KGDS), and range of motion (ROM) were compared between the two groups. Results: The experimental group showed significantly improved results in VAS, NDI, SAS, KGDS, and ROM after intervention (p<0.05), as did the control group (p<0.05). The comparison of changes in the experimental group before and after intervention showed superior results in the SAS, NDI, and ROM (flexion, rotation, lat. flexion) results when compared with the control group (p<0.05). Conclusion: Specific exercise is effective in the improvement of SAS, NDI, and ROM for elderly women with CNP.