• Title/Summary/Keyword: Crown length

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Finite Element Stress Analysis of Implant Prosthesis according to Position and Direction of Load (하중의 위치 및 경사에 따른 임플랜트 보철의 유한요소법적 응력분석)

  • Bae, Sook-Jin;Chung, Chae-Heon;Jeong, Seung-Mi
    • Journal of Dental Rehabilitation and Applied Science
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    • v.19 no.4
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    • pp.257-268
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    • 2003
  • The purpose of this study was to assess the loading distributing characteristics of implant prosthesis according to position and direction of load, under vertical and inclined loading using FEA analysis. The finite element model was designed according to standard fixture (4.1mm restorative component x 11.5mm length). The crown for mandibular first molar was made using UCLA abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric usp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant in both vertical and oblique loading but stresses in the cancellous bone were low in both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. 4. The relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 5. The magnitude of the stress in the supporting bone, fixture and abutment screw was greater with the outward oblique loading than with the inward oblique loading and was the greatest under loading at the centric cusp in a $30^{\circ}$ outward oblique direction. Conclusively, this study provides evidence that bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. But it seems to be more important that how long is the distance from center of rotation of the implant itself to the resultant line of force from occlusal contact(leverage). The goal of improving implants should be to avoid bending of the implant.

Measurement and Within-tree Distribution of Larval Entrance and Adult Emergence Holes of Japanese Pine Sawyer, Monochamus alternatus(Coleoptera: Cerambycidae) (솔수염하늘소의 유충침입공과 성충탈출공의 측정과 소나무 내 분포)

  • 정영진;이상명;김동수;최광식;이상길;박정규
    • Korean journal of applied entomology
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    • v.42 no.4
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    • pp.315-321
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    • 2003
  • Larval entrance and adult emergence holes of Japanese pine sawyer (Monochamus alternatus), primary vector of pinewood nematode (Bursaphelenchus xylophilus), were measured in dead pine logs from 1999 to 2002. Their distributions within pine log were also analyzed. More numbers of entrance and emergence holes were distributed on crown than trunk part as 56.2 and 27.7 holes/m$^2$, respectively Higher proportions of entrance (27.5%) and emergence holes (22.4%) were distributed on the log with 8 to 10 cm diameter; the larger or the smaller logs had fewer holes. Surface area of entrance hole was 65.8 $\textrm{mm}^2$ and diameter of emergence holes was 7.0 mm in average. Average depth of pupal chamber was 24.8 mm from surface to the bottom of the chamber, and its volume ranged from 200 to 2.000 ㎣ Average distance between entrance and emergence holes on bark surface was 3.3 cm. Gallery length from the beginning of entrance hole to the end of emergence hole was 46.2 mm.

A Study of Costumes in the Palace Painting Depicting the Worship of Buddha during the Reign of King Myungjong (관중숭불도에 나타난 16세기 복식연구)

  • 홍나영;김소현
    • Journal of the Korean Society of Costume
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    • v.38
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    • pp.305-321
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    • 1998
  • The costume style of the Chosun dynasty changed greatly after Imjinwaeran (the Japanese Invasion of Chosun Korea, 1592∼1598). Most of the extant costumes come from the late Chosun, but some costumes produced be-fore Imjinwaeran have been excavated, and in addition, information on these older constumes is contained in contemporary literature. Of especial value in the study of pre-Imjinwaeran Chosun constumes is a mid-sixteenth century palace painting depicting the worship of Buddha, a painting in the collection of the Ho-Am Art Museum in Seoul. The present study of costume during the middle Chosun dynasty focuses on this painting, and compares it with other contemporary palace paintings, and with other contemporary palace paintings, and with Nectar Ritual Paintings. The following conclusion were drawn : * Concerning woman's hair styles of the time, married women wore a large wig. Un-married women braided their hair, and then either let it fall down their back or wore it coiled on top of their head. * The major characteristic of woman's costumes was a ample, tube-like silhouette, with the ratio of the Jeogori(Korean woman's jacket) and skirt being one-to-one. * The style of Jeogori in the painting was like that of excavated remains. Some Jeogoris were simple (without decoration), while some Jeogoris were worn with red sashes. Here we can confirm the continuity of ancient Korean costumes with those of the sixteenth century * Although the skirt covered the ankles, it did not touch the ground. Because the breadth of the skirt was not wide, it seems to have been for ordinary use. Colors of skirts were mainly white or light blue. * All men in the painting wore a headdress. Ordinary men, not Buddhist monks, wore Bok-du (headstring), Chorip (straw hat), or Heuk-rip (black hat). In this painting, men wore a Heukrip which had a round Mojeong (crown). * The men wore sashes fastened around their waist to close their coats, which was different from the late Chosun, in which men bound their sashes around their chest. That gave a ration of the bodice of the coat to the length of the skirt of one-to-one, which was consistent with that of woman's clothing. * In this painting, we cannot see the Buddhist monk's headdress that appeared later in the Chosun, such as Gokkal (peaked hat), Songnak (nun's hat), and Gamtu (horsehair cap). These kinds of headdresses, which appeared in paintings from the seventeenth century, were worn widely inside or outside the home. Buddhist monks wore a light blue long coat, called Jangsam (Buddhist monk's robe) and wore Gasa (Buddhist monk's cope), a kind of ceremonial wrap, round their body. We can see that the Gasa was very splendid in the early years of the Chosun dynasty, a continuing tradition of Buddhist monk's costumes from the Koryo dynasty.

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Evaluation on Reinforcing Effect of Inclined System Bolting by Model Tests and Numerical Analysis (모형시험 및 수치해석을 통한 경사 시스템 록볼트의 보강효과 분석)

  • Lee, Jea-Dug;Kim, Byoung-Il;Yoo, Wan-Kyu;Han, Jin-Tae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.4
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    • pp.1529-1539
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    • 2013
  • Recent case studies in Japan have shown that rockbolts are commonly installed at an oblique angle to the excavation direction of the tunnel, instead of at a right angle, due to restriction of the working space. In particular, in the case of expansion in an existing tunnel, the working space can be very small, due to the large protective structures necessary to operate within an existing tunnel. In this case, where both the current use of the existing tunnel, and the reinforcement of the ground around the tunnel are required, the effects of installation angles and patterns of rockbolts are important factors in the design process. Therefore, in this study, a total number of 24 model tests are performed, to investigate the reinforcing effects of system bolting installed obliquely from the excavation direction of the tunnel, by changing the installation angle of bolts, longitudinal distance, and bonded length of bolts. The model test results indicate that the relaxed load ratio decreases, with the increase of both the bonded lengths and the number of the installed bolts, resulting in the decrease of the supported area by one bolt. Two-dimensional numerical analysis, which considered the reinforcement effect of inclined system bolting as the change of engineering properties near the tunnel, demonstrated that the deflection patterns at the tunnel crown in the numerical simulations, show a similar tendency to those measured in the model tests.

The Role of Cartilage Canals in Osteogenesis and Growth of the Vertebrae in the Human Fetuses (인태아 척추 골화과정에서 연골관의 역할)

  • Jung, Sung-Taek;Nam, Kwang-Il;Kim, Baik-Yoon;Yoon, Jae-Rhyong
    • Applied Microscopy
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    • v.31 no.3
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    • pp.287-305
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    • 2001
  • To investigate a role of cartilage canals in osteogenesis and growth of the vertebrae, in human fetuses ranging from 50 mm to 260 mm crown rump length were studied by electron microscopy. The initial appearance of cartilage canals of the vertebral body was observed at 60 mm fetus. In 80 mm fetus, primary ossification center in the vertebral body was first noted. The vertebral body showed calcified chondrocytes surrounded by a tone of hypertrophied chondrocytes and deep canals which terminated in calcified matrix. Most hypertrophied chondrocytes in the centrum showed in various stage of degeneration in disorderly arrangement. At the blind end of deep canal, osteogenic cells, osteoblasts and chondroclasts were observed. Resorption of unmineralized cartilage septa was undertaken by perivascular cells within cartilage canals. The ruffled border of the chondroclast was restricted to resorption site of calcified cartilagenous matrix. The periosteal bone formation was followed by the appearance of primary center of the centrum at 120 mm fetus. The osteoblasts of the perichondrium started to lay down a thin membranous bony lamella on the outer surface of the osseous trabeculae of the centrum. The processes of bone formation in the vertebral bodies were found to possess morphological similarities to that occurring at secondary center of the epiphysis of a long bone. These results indicate that the connective tissue cells within the cartilage canals proliferate and differentiate into osteoblasts at the site of endochondral ossification of the vertebrae.

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Experimental life history of Echinostoma hortense (호르린스극구흡충의 실험실 내 생활사에 대한 연구)

  • 이순형;황순옥
    • Parasites, Hosts and Diseases
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    • v.29 no.2
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    • pp.161-172
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    • 1991
  • The complete life cycle of Echinostoma hertense has been maintained in the laboratory, using Lymnaea persia snails and Rana nigromaculata tadpoles as the first and second intermediate hosts. ICR mice was used as the definitive host. Within the egg of 5. hotense, the miracidium was fully matured in 13 days of incubation at $29~30^{\circ}C$. The miracidium was $93.8{\times}53.6{\;}{\mu\textrm{m}}$ in average size, covered with numerous cilia of $7~11{\;}{\mu\textrm{m}}$ length. The epidermal plates were arranged in 6-8-4-2 formula. The first generation rediae ($1.19{\times}0.27{\;}mm$ in average size) were observed in 14 days after miracidial challenge to the snails, and the second generation rediae ($1.40{\times}0.26{\;}mm$ in average size) in 30 days. The average sixte of the cercaria was $295.5{\times}145.0{\;}{\mu\textrm{m}}$. Their head crown was poorly developed, and collar spines were not yet observed. After a cercarial challenge to the tadpoles, all of the tadpoles became infected and the average worm recovery rate was 88.5%. The majority of the metacercariae (75.5%) were recovered from the muscle of the tadpole's posterior body and the rest (24.3%) from their gills. The metacercariae from the tadpoles were elliptical, and $167.7{\times}129.9{\;}{\mu\textrm{m}}$ in average size. The recovery rate of adults from the mice was difFerent by the age of the metacercariae grown in the tadpoles. The metacercariae younger than 5 hrs could not infect mice whereas those older than 6 hrs could infect mice. The recovery rate became higher as the metacercaria matured, with the peak recovery rate of 90.0 % at the metacercarial age of 9 days. Thereafter the recovery rate decreased to 55.0% at the age of 50 days. As shown by the above results, the whole life cycle of E. hcrtense has been completed in the laboratory. At least 55~58 days were required to maintain one egg-to-egg cycle of E. hortense.

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Three Dimensional Analysis of Maxillary Mesiodens Using Dental CBCT and Relationship Between the Mesiodens and Diastema (치과용 CBCT를 이용한 상악 정중치의 3차원 분석 및 정중치와 정중이개와의 관계분석)

  • Kang, Eunjoo;Choi, Namki;Kim, Seonmi
    • Journal of the korean academy of Pediatric Dentistry
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    • v.40 no.4
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    • pp.260-267
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    • 2013
  • The aim of this study was to analyze the three dimensional characteristics of the size, shape and location of mesiodens and their effect on permanent teeth arrangement using Cone-beam computed tomography(CBCT). 191 patients under 15 years old who had visited the hospital between June 2006 and December 2012 and taken CBCT were investigated. Among them, 43 patients with diastema were analyzed to investigate the correlation between the amount of diastema and the mesiodens. The results showed that mesiodens were found in males 3.9 times more than females and found most in 7 years old. The mean length of mesiodens was 13 mm and the width was 6.8 mm. The conical shape comprised of 52.9%. Many mesiodens were located in the palatal side rather than the labial side and located vertically near the crown. 63.0% of mesiodens were reversed and the common complications were delayed eruption followed by diastema, and teeth rotation. And the amount of diastema had correlation with size and mesiodistal position of the mesiodens. The current study used 3D analysis to show the size and position of mesiodens and occurrence distribution of complication. Among these, the amount of diastema had shown the correlation with the size and mesiodistal position of mesiodens.

COMPARISON OF CANAL SHAPING METHODS WITH GTTM ROTARY FILE AND CONDENSATION METHODS (GT rotary file을 이용한 근관성형법과 충전방법의 비교)

  • Kang, Yu-Mi;Jin, Jeong-Hee;Yu, Mi-Kyung;Lee, Se-Joon;Lee, Kwang-Won
    • Restorative Dentistry and Endodontics
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    • v.27 no.5
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    • pp.521-529
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    • 2002
  • The purpose of this study was to compare the shaping time of two shaping methods and the leakage of three different obturation techniques. Ninty three canaled human molar teeth were used, which were randomly divided into two groups of forty teeth each and ten control teeth. After working length determination, the one group was prepared crown-down technique using rotary root canal instruments of GT rotary files .12/20, .10/20, .08/20 and .06/20 taper(Maillefer Instrument SA. Switzerland). The other group was instrumented with Gates Glidden burs(#1, #2, and #3) to coronal preparation and GT rotary files .08/20 and .06/30 taper to apical preparation. Shaping time was measured. After root canals were instrumented, they were divided to three subgroups and obturated as follows : Subgroup 1, obturated with single cone method Subgroup 2, obturated with lateral condensation : Subgroup 3, obturated with continuous wave technique. Three subgroups were obturated using non-standardized gutta-percha cone(Diadent, Korea, .06 or .08 taper) and AH-26(Dentsply DeTrey, Germany) as a root canal cement. Ten unobturated teeth served as positive and negative controls. After immersion in 2% methylene blue solution for 1 month, the teeth were washed during 24h. The teeth were demineralized in 10% nitric acid and dehydrated by immersion in 80, 90 and 100% ethyl alcohol. The teeth were finally cleared and stored in 100% methylsalicylate, and apical dye penetration was evaluated under stereomicroscope(Leica M420, LC, U.S.A)at $\times$8.75 magnification. Liner measurement of dye penetration was assessed with the use of digitalized image analysing system (analySIS, GmbH, Germany) The data were analysed statistically using independent T-test and Two-way ANOVA and Tukey test. The result were as follows 1. In canal prepared with GT$^{TM}$ rotary file, shaphing time taked more than the group of using Gates Glidden drill to coronal preparation without statistical significance (p>0.05) 2. The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files showed significantly more apical leakage than those of lateral condensation and continuous wave technique regardless of shaping method (p<0.05). 3 The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files and Gates Glidden drill showed significantly more apical leakage than those of continuous wave technique regardless of shaping method (p<0.05). 4. Regardless of shaping method, The group of continuous wave obturation showed less apical leakage than those of lateral condensation without statistical significance (p>0.05). 5. The group of single cone obturation using canal preparation of GT$^{TM}$ rotary files and Gates Glidden drill showed more apical leakage than the group of lateral condensation using same shaping method with-out statistical significance (p>0.05).

Effect of Fruit Thining for Hydroponics on the New Domestic Strawberry Cultivars 'Daewang', 'SSanta', 'Okmae', 'Seolhyang' and 'Maehyang' (딸기 '대왕', '싼타', '옥매', '설향' 및 '매향' 품종의 수경재배시 착과수 조절 효과)

  • Jeong, Ho-Jeong;Rho, Il-Rae;Kim, Byung-Su
    • Current Research on Agriculture and Life Sciences
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    • v.31 no.4
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    • pp.265-271
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    • 2013
  • The objective of this study was to find out the optimum number of fruiting per a flower cluster on 5 domestic strawberry cultivars (Fragaria${\times}$ananassa Duch.), 'Daewang', 'Ssanta', 'Okmae', 'Seolhyang' and 'Maehyang'. Therefore, three ways of fruit thinning, 4~5 fruiting, 7~9 fruiting and all fruiting per a flower cluster were compared. After fruit thinning, the first fruit weights were increased from the second flower cluster on 'Seolhyang' and 'Maehyang', but from the third one on 'Daewang' and 'Ssanta'. There was no difference in first fruit weight by the flower thinning ways on 'Okmae'. The mean fruit weights of all the cultivars were increased and sugar contents also were increased, but acidities were decreased. The peduncle lengths were shortened by fruit thinning, but there was no difference in number of leaf, petiole length and crown diameter. Marketable yields by 4~5 fruiting per a flower cluster than all the fruit setting were higher 4.3% and 6.6% respectively on 'Daewang' and 'Maehyang'. In contrast, the yields were higher 3.1%, 3.5% and 9.1% in 7~9 fruiting per a flower cluster than all fruiting on 'Ssanta', 'Okmae' and 'Seolhyang' respectively. As the result, we could improve the fruit quality and could increase marketable yield by fruit thinning with matching flowering characteristics of those strawberry cultivars.

The effect of thiamin on fetal growth and development in CD-1 mice exposed with mercury for the gestation period (임신 중 수은을 섭취한 CD-1 마우스 태아의 성장발육과 기형발생에 미친 티아민의 효능 평가)

  • Kim, Jin-suk;Choi, Seok-wha
    • Korean Journal of Veterinary Research
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    • v.34 no.1
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    • pp.69-75
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    • 1994
  • Pregnant CD-1 mice were exposed to methylmercury in the drinking water at concentration of 20ppm with subcutaneous treatment of thiaminHCl(vitamin $B_1$) (100mg, 200mg or 300mg/ kg b.w.) or BAL(5.0 mg/kg b.w.) under the alone or combined base at the therapeutic agents from day 6 to 15 of gestation. Fetal growth parameters, including body weight and crown-rump length in the mice exposed to mercury, were reduced as placental weight compared to those in the control group(no treatment). The incidence of dead fetuses/resorption and malformed fetuses(especially cleft palate) was also increased even in the group treated with thrapeutic agents as well as in the mercury only treated group. However, all kinds of alteration indicated above, possibly induced by mercury, reduced/or decreased significantly compared to those of control. A subtle indication of maternal toxicity was noted in most experimental animals as evidenced by decreased water consumption and increased relative liver weight. The present study confirmed that methylmercuric chloride is embrytoxic and teratogenic in CD-1 mice when administered during organogenesis and that thiamin administration may have therapeutic application for the treatment or prevention against of deleterious effects induced by mercury during gestation period.

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