• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.249-258
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• 2013

The purpose of this study was to investigate how image magnification in dental panoramic radiography is influenced by object position. Five metal balls (4 mm in diameter, 2 for the anterior and 3 for the posterior region on the right side) were placed above alveolar crest of dry skull considering extraction socket and dental arch. Dry skull was radiographed using OP-100D (Instrumentarium Imaging Co., Tuusula, Finland) at proper and displaced position along the sagittal and transverse plane at 3 mm, 6 mm, 9 mm, 12 mm and 15 mm using special mount which can control precise movement. Images were stored in DICOM files and were measured by ruler equipped within INFINITT PACS software (Infinitt Co., Ltd., Seoul, Korea). The mean horizontal magnification was 1.224-1.439 and mean vertical magnification was 1.286 - 1.345 at proper position. Vertical magnification resulted in less variation (1.245-1.418) than horizontal magnification (0.798-6.297) according to the sagittal and transverse displacements. Head positioning is important for linear measurement on panoramic radiography and inclusion of standard object (for instance, metal ball) is helpful to anticipate exact magnification of panoramic radiographs at various location.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.185-194
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• 2001

This study was designed to evaluate the effects of angulation changes of head posture on the enlargement ratios of a lateral headfilm depending on the vortical or horizontal rotation of the objects. A device was constructed to measure regional changes of enlargement ratios. The device was held within the cephalostat and cephalograms recorded at each measured degrees of the device tilting, vertically and horizontally. The enlargement ratios of the horizontal, vertical, and angular measurements on the films taken at each tilted angulations were obtained and compared with those on the films taken without rotation. In summary, the enlargement ratios of the horizontal linear measurements were decreased during horizontal rotations. The enlargement ratios of vortical measurements of the right side on the film were increased and those of the left side were decreased by the horizontal rotations. Enlargement ratios of horizontal measurements were affected further than those of vertical measurements by the same angular changes of the horizontal rotations. Therefore, a disruption of parallelism between the object's midsagittal plane and the film could result in distortion of the image while vertical rotation around the object's porionic axis would not significantly affect the enlargement ratios on the headfilm.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.1-8
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• 2014

Purpose: The purpose of this study was to investigate the effect of head position changes on vertical and horizontal magnification in dental panoramic radiographs. Materials and Methods: Five 4 mm metal balls were placed above alveolar crest of dry skull considering extraction socket and dental arch. Panoramic radiographs were taken by OP-100D (Instrumentarium Imaging Co., Tuusula, Finland) at proper and rotated head position along the sagittal and transverse axis at 3 - $20^{\circ}$ upwardly, downwardly, to the left and to the right rotation. Images were stored in DICOM files and were measured by ruler equipped within INFINITT PACS software. Results: The mean horizontal magnification was $1.22{\pm}0.01-1.44{\pm}0.01$ and mean vertical magnification was $1.29{\pm}0.00-1.35{\pm}0.02$ at standard head position. There was statistical significance of horizontal magnification between the anterior ($1.24{\pm}0.02-1.31{\pm}0.03$) and the posterior area ($1.40{\pm}0.03-1.33{\pm}0.02$) (P < 0.05). Vertical magnification resulted in less variation ($1.24{\pm}0.01-1.37{\pm}0.02$) than horizontal magnification ($0.88{\pm}0.03-3.73{\pm}0.16$) according to the rotation. There was statistical significant difference on horizontal magnification (P < 0.05). Conclusion: In rotated head position, the horizontal magnification should be considered because these can cause distortion on panoramic radiographs.

• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.3
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• pp.282-288
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• 1982

크랙탄성평판의 굽힘문제가 경계적분방정식으로 구성되었다. 자연변수인 변위, 수직기울기, 굽힘 모우멘트, 등가전단적과 크랙끝에서 응력의 성장율로 정의되는 응력확대계수들이 주변수로 포함 된다. 이 적분방정식들은 가역에너지 적분이론(Green-Rayleigh)을 기초로 크랙응력분포특성에 맞 게 발전되었으며 해당되는 핵함수들이 유도되었다. 등분석 모우멘트를 받는 중앙크랙이 있는 정 4각형 모형에 대한 응력확대계수가 계산되어 기존의 유한요소법의 해와 비교되었다.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.222-232
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• 2014

Purpose: This study aims to investigate if 2D analysis method is applicable to analysis of CBCT by comparing measuring points of CBCT with those of Adjusted 2D Lateral Cephalogram (Adj-Ceph) with magnification adjusted to 100% and finding out at which landmarks the difference in position appear. Materials and methods: CBCT data and Adj-Ceph (100% magnification) data from 50 adult patients have been extracted as research objects, and the horizontal (Y axis) and vertical (Z axis) coordinates of landmarks were compared. Landmarks have been categorized into 4 groups by the position and whether they are bilaterally overlapped. Paired t-test was used to compare differences between Adj-Ceph and CBCT. Results: Significant difference was found at 11 landmarks including Group B (S, Ar, Ba, PNS), Group C (Po, Or, Hinge axis, Go) and Group D (U1RP, U6CP, L6CP) in the horizontal (Y) axis while all the landmarks in vertical (Z) axis showed significant difference (P<.05). As a result of landmark difference analysis, a meaningful difference with more than 1 mm at 13 landmarks were indentifed in the horizontal axis. In the vertical axis, significant difference over 1 mm was detected from every landmark except Sella. Conclusion: Using the conventional lateral cephalometric measurements on CBCT is insufficient. A new 3D analysis or a modified 2D analysis adjusted on 19 landmarks of the vertical axis and 13 of the horizontal axis are needed when implementing CBCT diagnosis.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.294-295
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• 2003

OCT(Optical Coherence Tomography) 기술은 기본적으로 낮은 가간섭성 광원의 빛을 대상물에 주사하여 피대상물의 내부구조에 따른 각종 광학정 수치를 높은 수직 분해능으로 깊이별로 얻어낼 수 있는 기술이다. 현재 많은 생체 연구그룹에서 OCT의 개발과 응용에 대해 적극적인 연구가 진행 중에 있으며, 그 적용분야를 확대하고 있는 추세이다. OCT에 관련된 대표적인 연구분야로서 조직의 미세 단층영상, 혈류 가시화 및 각종 생체조직에 따른 복굴절율 변화 측정 등이 있다.(중략)

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.277-285
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• 2008

For the soil nailing, recently, its application is expanded, but there is no officially approved method to design it yet. Furthermore, there are a great number of design valuables in soil nailing, it is also used without clear data under the situation that uncompleted detailed research on the sensibility between design variables. Especially, there has no deal with the installation angle of the nail - the major contents in this study. Therefore, this study based on the theoretical estimation analyzed safety rate about the angle of the nail, unit weight, adhesive force, internal friction angle and tensile farce worked on nail in the case of the rear of pond side is both horizontal and perpendicular. As a result, it could be verified that the safety rate increased on every cases in the situation of the nail installation angle was in upward direction than in downward direction.

• The korean journal of orthodontics
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• v.27 no.1
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• pp.79-89
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• 1997

One of the strenuous problems in orthodontic procedures is postretention stability and retention against relapse. Many investigative trial had been done to disclose the factors associated with relapse and effective prescription to stave off, however, the nature of these jeopardies remained obscure. The objective was to investigate the long-term stability and quantitative changes of dental arches subsequently after Class I nonextraction treatment. Study models,cephalometric headfilms of 26 samples which were taken before, after teatment and postretention were employed to measure the interdental width of corresponding buccal teeth,overbite,overjet and the inclination of incisors and molars. Statistical analysis was carried to compare each measurements across the time period, and followings were brought around. 1. The quantitative amount of relapse in overbite presented positive correlation with the amount of changes through the treatment. 2. Stability of intercanine width was so far secure in the case the expansion had been done through. 3. The amount of changes in intercanine width of the lower regardless of expansion or contraction manifested less than the upper, however, the relapse ratio got high. 4. The upper and lower incisors were likely to be labioversive, and remained stable after retention. 5. The first molars of the upper and lower were conceivably tipped back immediately after treatment and returned to the original angulation. The expansion of intermolar width stayed stable across the time scheme after treatment It was suggested that the maintenance of intercanine width of lower was pertinent to perform the postretention stabilityv and the expansion of dental arch shoed be confined within physiologic boundaries of the patients.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.225-240
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• 2022

Gyeonggi-do comprises several types of areas, including urban, semi-urban, and rural areas. The availability of public transportation services varies depending on the area types, but the fare structure is based on a simple transfer rule, i.e., a transfer is free when completed within 30 minutes. As a result, users in non-urban areas with a poor frequency of public transportation services do not receive transfer discounts because most of the bus routes in these areas have a gap of more than 30 minutes between services. In terms of equality of opportunity, the transfer rule is being applied unfavorably and, as a result, equality of opportunity of the non-urban commuter is severely affected. Therefore, this study analyzed the user benefits mainly stemming from transfer fares using the smart card data of commuters using public transportation in Gyeonggi-do. An index called the beneficiary rate of the free transfer was developed and a scenario analysis was conducted based on the various levels of the rate. The results of this analysis proved that the users of public transportation services in non-urban areas in Gyeonggi-do can only receive transfer benefits by the extended time for free transfer and not by the implementation of a uniform policy irrespective of the type of area. The study also suggested an equitable fare transfer system and policy alternatives.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.07a
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• pp.347-352
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• 2003

농산물 포장화물의 경우 농산물의 손상은 겉포장 상자의 파손에 의한 압상이 주요 원인이다. 따라서 농산물 상자의 경우 압축강도를 특히 중요시 여기고 있으며, 한국산업규격을 비롯해 각종 농산물 관련 규정에서는 압축강도에 의한 상자의 품질관리를 규정화 하고 있다. 골판지 상자의 압축강도는 원단인 골판지의 구성 원지들(라이너, 골심지)의 품질과 이들의 구성 형태 및 상자의 외형 치수 비율에 따라 결정되므로, 원지의 링크라쉬(ring crush), 원단의 수직압축강도(edgewise compression strength)를 통해 상자의 압출강도를 관리하는 것이 보통이다. 또한 골판지 상자는 제작 후 유통 과정을 거치면서, 여러 요인에 의해 압축강도가 현격하게 저하되는데, 이중 수분 흡습에 의한 강도저하와 장기 누적하중, 진동 및 충격 등의 피로로 인한 강도 저하가 가장 크다. 여러 산업 분야에서 골판지 상자의 견고성 문제는 물품의 내수 및 수출시 제품에 대한 신뢰성 확보와 기업의 이미지 제고와 직결되는 중요한 사항이다. 특히, 세계 각 국의 농산물 시장이 개방됨에 따라 우리나라 농산물의 수출도 확대될 전망이고 또한 마땅한 대체재가 개발되지 않는 한 골판지 상자의 이용은 날로 증가될 것으로 전망된다. 따라서 골판지 상자의 압축강도와 내구성 향상에 대한 다각적인 연구가 절실하다. (중략)