• 대한조선학회지
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• 제7권2호
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• pp.27-40
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• 1970

The distribution of stress and strain in elastic stages is investigated by the experiments of two dimensional photoelastic coating and Moire fringe method. Center block type and cover plate type of fillet welds are used as specimens in the test. The results are as follows. 1) Center block type gets less uniform stress distribution than cover plate type. And its stress concentration factor, especially at root, is larger than that at toe. 2) When main plate and cover plate closely contact and it cause friction, stress concentration decreases more than that in case of slit. That is because stress can be transmitted on the contact surface. 3) When slit is made, the outside of fillet gets more stress than the inside of it. 4) While the plastic strain distribution of center block type reaches the maximum at root and differs very slightly from that under lower loading, the plastic strain distribution of cover plate type is inclined to get the maximum at the outside of fillet rather than at root. 5) When the plastic strain value of cover plate type is compared with that of center block type at toe and root, the relations between the former and the latter shows root<toe and root>toe. 6) Because stress distribution becomes changed according to loading, fracture angle cannot be estimated by the peaks of elastic stress distribution. 7) The strain distribution just before fracture can be found by Moire fringe method.

• Journal of Plant Biology
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• 제31권3호
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• pp.169-185
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• 1988

Vessel elements in lateral root, tap root, transition region, stem and mid vein of 1-year old, 3-year old and 5-year old ginseng (Panax ginseng C.A. Meyer) are studied with light microscope to clarify the distribution and differentiation of several kinds of vessel elements. Vessel elements are classified into five types such as ring vessel, spiral vessel, scalariform vessel, reticulate vessel and pitted vessel according to the secondary thickenings of cell wall. All of the five types are not observed in each organ, but diverse kinds of vessels are present in stem and mid vein compared with the underground organs such as tap root and lateral root. The length of vessel elements is longest (680$\mu$m) in stem and shortest (143$\mu$m) in tap root. The diameter of vessel elements is 19.0$\mu$m in tap root and the angle of perforation plate comes under 22$^{\circ}$-60$^{\circ}$. The degree of differentiation of vessel elements according to the length, diameter and angle of perforation plate of vessel elements is highest in tap root regardless of the age of ginseng. Three types of perforation plate such as scalariform, intermediate type of simple and scalariform, and simple perforation plate are observed. The vascular tracheids are characteristically observed in mid vein of 1-year old ginseng, and in transition region of 3 and 5-year old ginseng.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.151-154
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• 2007

To build up the green roofs, it must not adverse effect to durability and structural safety. That is conducted by safety system which consist of waterproofing to form basically, root barrier to protect the waterproofing. The reason why root barrier form is to protect the penetration force of root growth and the root could penetrate concrete surface, move inward so far. It may cause shorten the life span on concrete structure. For this problem, government constantly demand the solution to form the root barrier for waterproofing and concrete structure before the building is service. However, the technical action is not fully prepared. Therefore, in this study, we would like to suggest the workability and suitability of the copper plate to solve not only the side of waterproofing but also root barrier for green roof system and exhibit the mechanism for root penetration resistance and corrosion resistance.

• Imaging Science in Dentistry
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• 제42권4호
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• pp.219-224
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• 2012

Purpose: This study investigated the relationship between the roots of the maxillary molars and the maxillary sinus using cone beam computed tomography (CBCT), and measured the distances between the roots of the maxillary molars and the sinus floor as well as the thickness of the bone between the root and the alveolar cortical plate. Materials and Methods: The study sample consisted of 83 patients with normally erupted bilateral maxillary first and second molars. A total of 332 maxillary molars were examined using CBCT images. The vertical relationship of each root with the maxillary sinus was classified into four types on CBCT cross-sectional images. The distance between the sinus floor and root and the bone thickness between the root and alveolar cortical plate were measured. Results: In the buccal roots of the maxillary molars, a root protruding into the sinus occurred most frequently. A root projecting laterally along the sinus cavity was most common in the palatal roots of the maxillary first molars. The mesiobuccal roots of the maxillary second molar were closest to the sinus. The mesiobuccal roots of the first molars were closest to the cortical plate. Conclusion: The relationship between the roots of the maxillary molars and the sinus differed between the buccal and palatal roots. A root protruding into the sinus occurred more frequent in the buccal roots of the maxillary molars. The mesiobuccal root of the maxillary second molar was closest to the maxillary sinus floor and farthest from the alveolar cortical plate.

• 대한조선학회지
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• 제20권4호
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• pp.17-24
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• 1983

In this study, it was investigated the distribution of residual stress in the direction of loading between the root and toe the load fillet welds for thick steel plate. Residual stress distributions are measured by sectioning method which is one of stress-relaxation technique in welded joint, and analyzed by two dimensional finite element method on thermo-elasto-plastic theory under plane stress condition. These are compared the results of F.E.M analysis with the experimental result by stress-relaxation techniques. As a results, the following conclusion were obtained. (1) In the no penetration fillet welded joint specimen using mild steel plate with 25mm in thickness, the residual stress of loading direction near the root was about $10kg/mm^2$ tensile. (2) The tensile residual stress has been observed in fillet region of the fillet joint by F.E.M. analysis method. (3) The range of compressive residual stress distribution from the root was largest in the case of 5mm root penetration.

• The Journal of Advanced Prosthodontics
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• 제2권3호
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• pp.92-96
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• 2010

PURPOSE. The aim of this study was to evaluate the thickness of buccal and palatal alveolar bone and buccal bony curvature below root apex in maxillary anterior teeth of Korean adults using Cone-beam CT images. MATERIALS AND METHODS. The 3D image was reconstructed with dicom file obtained through CBCT from 20 - 39 year old Korean subjects (n = 20). The thickness of buccal and palatal plate, root diameter, the buccal bony curvature angle below root apex and the distance from root apex to the deepest point of buccal bony curvature were measured on maxillary anterior teeth area using OnDemand3D program. RESULTS. Mean thickness of buccal plate 3 mm below CEJ was $0.68{\pm}0.29\;mm$ at central incisor, $0.76{\pm}0.59\;mm$ at lateral incisor, and $1.07{\pm}0.80\;mm$ at canine. Mean thickness of palatal plate 3 mm below CEJ was $1.53{\pm}0.55\;mm$ of central incisor, $1.18{\pm}0.66\;mm$ of lateral incisor, $1.42{\pm}0.77\;mm$ of canine. Bucco-lingual diameter 3 mm below CEJ was $5.13{\pm}0.37\;mm$ of central incisor, $4.58{\pm}0.46\;mm$ of lateral incisor, and $5.93{\pm}0.47\;mm$ of canine. Buccal bony curvature angle below root apex was $134.7{\pm}17.5^{\circ}$ at central incisor, $151.0{\pm}13.9^{\circ}$ at lateral incisor, $153.0{\pm}9.5^{\circ}$ at canine. Distance between root apex and the deepest point of buccal bony curvature of central incisor was $3.67{\pm}1.28\;mm$ at central incisor, $3.90{\pm}1.51\;mm$ at lateral incisor, and $5.13{\pm}1.70\;mm$ at canine. CONCLUSION. Within the limitation of this study in Korean adults, the thickness of maxillary anterior buccal plate was very thin within 1mm and the thickness of palatal plate was thick, relatively. The buccal bony curvature below root apex of maxillary central incisor was higher than that of lateral incisor and canine and it seems that the buccal bony plate below root apex of central incisor is most curved.

• Journal of Plant Biology
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• 제28권2호
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• pp.127-140
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• 1985

본 연구에서는 한국산 자작나무과 식물 5속 6종의 뿌리와 줄기의 이기목부를 비교해부학적으로 연구하였다. 뿌리와 줄기의 이기목부에 있어서 해부학적 특징은 도관 및 섬유의 직경은 줄기에 비해 뿌리에서 더 넓은 반면 단위면적당 도관 및 섬유의 분포수는 뿌리에서 더 적었으며, 도관요소의 길이는 줄기에서 더 긴 반면 섬유의 길이는 뿌리에서 더 길었다. 천공판상의 횡대수는 뿌리보다 줄기에서 더 많았고, 단위면적당 방사조직의 수는 뿌리에서 더 많았다.

• International Journal of Railway
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• 제5권2호
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• pp.89-92
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• 2012

Effective notch stress, as an approach to evaluate the local stress at a notch (weld toe or root), is defined as the total stress assuming linear-elastic material behavior. This method can be effectively used to evaluate the fatigue performance of welded joints. In this study, finite element analysis results using the effective notch stress method were correlated with fatigue test results of rib-to-deck welded joints in a steel orthotropic bridge deck. Effective notch stress approach provided a good correlation with the crack pattern observed in the full-scale fatigue test. A higher effective notch stress at the critical weld toe than at the weld root was consistent with the dominant crack pattern observed at the weld toe during testing. The effective notch stress at the toe on the deck plate was about 80% higher than that on the rib; no cracks at the weld toe on the rib in the testing were observed. Maximum effective notch stress at the weld root occurred on the upper side of the root notch, which indicates that cracks are more likely to propagate into the deck plate, not into the weld metal. This is also consistent with the observed crack pattern in which the crack from the root propagated upward into the deck plate. No such crack pattern, propagating into the weld metal, was observed in the testing.

• 한국산림과학회지
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• 제103권2호
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• pp.248-257
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• 2014

이 연구는 풍도목 근분의 구조형태적 특성을 파악하고, 풍향에 대응하는 수목뿌리의 발달 특성 및 수목의 지상부와 지하부 특성 간의 상관관계를 분석하고자 하는 목적으로 수행되었다. 이를 위해서 서울대학교 태화산 학술림에서 발생한 77 그루의 낙엽송과 24 그루의 잣나무 풍도목의 근분에 대한 현장조사를 실시하였다. 근분의 형태적 특성을 조사한 결과, 풍도목 근분은 타원형 혹은 원형의 평면형을 보이며, 측면에서 살펴보면 반 타원체의 형태를 보였다. 또한, 근분 내 뿌리의 발달 특성을 조사한 결과, 평균적으로 수목의 전도 방향에서 비전도 방향보다 뿌리의 개수가 더 많고, 뿌리 표면적이 더 큰 것으로 나타났다. 또한, 수목의 지상부와 지하부 특성 간의 선형상관관계를 조사한 결과, DBH는 수고보다 근분 크기와 뿌리 표면적에 대해 상대적으로 강한 선형적인 상관관계를 보였다. 이러한 상관관계 분석 결과를 토대로 상관관계가 뚜렷한 수목 지상부와 지하부 특성 간의 단순선형회귀식을 수립하였다.

• Restorative Dentistry and Endodontics
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• 제47권3호
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• pp.33.1-33.10
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• 2022

Objectives: This study aimed to analyze the proximity of maxillary molar roots to their overlying cortical bone surfaces and the maxillary sinus. Materials and Methods: Cone-beam computed tomographic images of 151 patients with completely erupted upper molars that had 3 separate roots were studied. The following distances were measured: from the root apex to the cortical plate and maxillary sinus floor, and from the apical 3-mm level of the root to the cortical plate. Differences between groups were analyzed with 1-way analysis of variance and the Scheffé post hoc test, the significance of differences between cone-beam computed tomography views with the paired t-test, and the significance of differences among age groups with linear regression analysis. The significance level was set at p < 0.05. Results: The mesiobuccal and distobuccal root apexes of maxillary second molars were more distant from the buccal cortical plate than the maxillary first molars (p < 0.05). The apical 3-mm level of the mesiobuccal root of the first molar was closer to the buccal cortical bone than the second molar (p < 0.05). In the maxillary first molars, the thickness of the buccal cortical bone decreased in all roots with age (p < 0.05). In all root apexes of both molars, the difference in the vertical level between the maxillary sinus floor and the root apex increased with age (p < 0.05). Conclusions: Awareness of the anatomical profile of maxillary molar apices in relation to the cortical bones and maxillary sinus will be beneficial for apical surgery.