• Title, Summary, Keyword: attrition

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A Study on the Attrition of Maxillary Lateral Incisors in Korea (상악 측절치의 교모에 관한 연구)

  • Lim, Byung-Chul
    • The Journal of Korean Academy of Dental Technology
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    • v.18 no.1
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    • pp.117-127
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    • 1996
  • This study was aimed to help the construction of esthetic dental prosthesis by investigation of the factors affecting on the atterition position and attrition angle of maxillary lateral incisors. Therefore 197 complete cast of maxillary and mandibualar extracted form the student of K. college were subjected for this study, and result throught the study are as follows. 1. None attrite rate of the maxiilary right lateral incisors was about 16.2% and that of the maxillary left lateral incisors was about 32.4% of examined teeth. 2. Throught mesiodistal attrition area 1) It showed that right lateral incisors was the most frequence in attrition of mesial area of incisal edge, and left lateral incisors was the most frequence in attrition of mesial and mid area of incisal edge. 2) It showed that square type arch was more frequence in attrition of all incisal edge, and ovoid type arch was more frequence in the attrition of mid area of incisal edge, and ovoid type arch was more frequence in the attrition of mid area of incisal edge, and taper type arch was more frequence in the attrition of mesial area of incisal edge than it of average frequence of right lateral incisors, by dental arch type. 3) It showed that square type arch was more frequence in the attrition of all area and mid area of incisal edge, and ovoid type arch was more frequence in the attrition of mid area of incisal edge, and taper type arch was more frequence in the attrition of mesial and distal area of incisal edge than it of average frequence of left lateral incisal, by dental arch type. 4) Sex, vertical overlap, horizontal overlap, incisal guide angle, did not affect significantly to throughout mesiodistal attrition, statistically 3. Throughout labiolingual attrition quantity. 1) It showed that throughout labiolingual attrition quantity was more attrition in order of taper type arch < ovoid type arch < square type arch, by dental arch type. 2) It showed that throughout labiolingual attrition qauntity was more attrition when the length of horizontal overlap is shorter than it of other, by horizontal overlap. 3) Throughout labiolingual attrition quantity of right lateral incisors showed that male was more attrition than it of female. 4) Vertical overlap, incisal guide angle, sex on left lateral incisors did not affect significantly to throughout labiolingual attrition, statistically. 4. Attrition angle 1) It showed that average attrition anlge of right lateral incisors were $30{\pm}13.02$ degree, and it of left lateral incisors were $26{\pm}13.37$ degree. 2) It showed that taper type arch have a bigger attrition angle than it of average of lateral incisors, and square tape arch have a smaller attrition angle than it of average of lateral incisors, by dental arch type. 3) It showed that horizontal overlap of 2.1mm above have a bigger attrition angle than it of average, by horizontal overlap. 4) It showed that female have a bigger attrition angle it of male, by sex.

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A Study on the Attrition of Maxillary Canine in Korea (상악 견치의 교모에 관한 연구)

  • Lim, Byung-Chul
    • The Journal of Korean Academy of Dental Technology
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    • v.19 no.1
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    • pp.121-130
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    • 1997
  • This study was aimed to help the construction of naturally dental prosthesis by investigation of the factors affecting on the attrition position and attrition angle of maxillary canines. Therefore 163 complete cast of maxillary and mandibular extracted from the student of K. college were subjected for this study, and result through the study are as follows. 1. None attrite rate of the maxillary canine was 7%, of examined teeth. 2. Throughout mesiodistal attrition of 1) Throughout mesiodistal attrition area of the maxillary canines showed that mesial area and mid area of cusp was more frequence in attrition than distal area of it. 2) Sex, dental arch type, vertical overlap, horizontal overlap, did not affect significantly to throughtout mesiodistal attrition statistically 3. Througout labiolingual attrition area 1) Throughout labiolingual attrition area of the maxillary canines showed that attrition of the from lingual to labioncisal edge was more frequence than it of linguoincisal edge 2) It showed that attrition of the from lingual to labioincisal edge was more frequence when the length of horizontal overlap is shorter, by horizontal overlap 3) The attrition of the from lingual to labioincisal edge in maxillary left canines showed that male was more frequence in attrition than female. 4) Dental arch type, vertical overlap, did not affect signioficantly to labiolingual attrition, statistically. 4. Attrition angle 1) It showed that average attrition angle of the maxillary right canines were $19{\pm}11.02$ dagree, and it of left canines were $18{\pm}11.83$ degree. 2) It showed that famale have a bigger attrition angle than male, by sex. 3) It showed that attrition angle was bigger when the length of horizontal ovelap is bigger, by horizontal overlap.

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Attrition Characteristics of WGS Catalysts for SEWGS System (SEWGS 시스템을 위한 WGS 촉매들의 마모특성)

  • Ryu, Hojung;Lee, Dongho;Lee, Seungyong;Jin, Gyoungtae
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.2
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    • pp.122-130
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    • 2014
  • Attrition characteristics of WGS catalysts for pre-combustion $ CO_2$ capture were investigated to check attrition loss of those catalysts, to check change of particle size distribution during attrition tests, and to determine solid circulation direction of WGS catalysts in a SEWGS system. The cumulative attrition losses of two catalysts increased with increasing time. However, attrition loss under humidified condition was lower than that under non-humidified condition case for long-term attrition tests. Between two catalysts, attrition loss of PC-29 catalyst was higher than that of MDC-7 catalyst for long-term attrition tests. However, the MDC-7 catalyst generated much more fines than PC-29 catalyst during attrition. Therefore, we conclude that the PC-29 catalyst is more suitable for fluidized bed operation if we take into account the separation efficiency of cyclone. Based on the results from the tests for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor.

A Study on the Attrition Pattern of Upper Premolar Teeth in Korean Male (한국인 남자 상악소구치의 교모형태에 관한 연구)

  • 이승우
    • Journal of Oral Medicine and Pain
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    • v.6 no.1
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    • pp.5-8
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    • 1981
  • The author had sellected stone models of upper premolar teeth from 20 age to 60 ages in male, and studied the attrition pattern of upper premolar teeth having attention to teeth cups on the stone model. All of the attrition patterns were divided (into) 14 forms. The results were as follows : 1. Attrition patterns of upper premolar teeth were divided into 14 forms. 2. Being compared with age group, early attrition pattern (M) showed decreasing tendency and late attrition pattern (A) showed incresing tendency by aging.

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The Characteristics of Attrition of Absorbents for Pre-combustion CO2 Capture (연소 전 CO2 포집 흡수제들의 마모특성)

  • Ryu, Hojung;Lee, Dongho;Moon, Jongho;Park, Youngcheol;Jo, Sungho
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.5
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    • pp.428-436
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    • 2013
  • Attrition characteristics of $CO_2$ absorbents for pre-combustion $CO_2$ capture were investigated to check attrition loss of those absorbents and to determine solid circulation direction and the better $CO_2$ absorbent. The cumulative attrition losses of two absorbents increased with increasing time. However, attrition loss under a humidified condition was lower than that under a non-humidified condition case. Between two absorbents, attrition loss of PKM1-SU absorbent was higher than that of P4-600 absorbent. The average particle sizes of the attrited particles were less than $2.5{\mu}m$ for two absorbents under a non-humidified condition case, and therefore, we could conclude that the main mechanism of attrition for two absorbents is not fragmentation but abrasion. Based on the results from the test for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor. Attrition loss and make-up rate of two absorbents were compared based on the results from $CO_2$ sorption capacity tests and attrition tests. Required make-up rate of P4-600 absorbent was lower than that of PKM1-SU absorbent. However, more detail investigation on the optimum regeneration temperature, manufacturing cost, solid circulation rate, regeneration rate, and long-term sorption capacity should be considered to select the best $CO_2$ absorbent.

A Study on the Age Estimation Based upon Attrition of Molars (증령에 따른 구치의 학모면적비에 관한 연구)

  • 양무도;이승우
    • Journal of Oral Medicine and Pain
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    • v.6 no.1
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    • pp.91-100
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    • 1981
  • The author collected 146 men's stone models and 175 women;s stone models over the age of twenties, and studied area ratio of attrition of molars. Area ratio of attrition = (area of attrition / area of occlusal surface)*100(%) All data were analyzed by means of statistical method, and following results were obtained. 1. There was correlation between age and area ratio of attrition, that is, area ratio of attrition was increased with aging process. 2. Regression equtions and coefficients of correlation showed a significant meaning. 3. Generally, upper teeth showed higher tendency of area ratio of attrition, being compared with lowers. 4. Being compared with male and female, there was no uniform difference.

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A Study on the Attrition Pattern of Posterior Teeth in Adult (성인구치의 교모형태에 관한 연구)

  • 박영식;김영구
    • Journal of Oral Medicine and Pain
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    • v.6 no.1
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    • pp.57-82
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    • 1981
  • The author had collected the full mouth stone model of 277 persons from 20 ages to 60 ages and studied the attrition pattern of posterior teeth paying attention to the teeth cusps on the stone model. All of the attrition patterns were classified by age, sex and analyzed. The results are followings : 1. Attrition patterns of posterior teeth were divided into 64 forms.(expept 3rd molar) 2. There was no significant difference between right & left. 3. Generally early attrition pattern of younger age and late attriction pattern of older age were more prominent in men being compared with sexual difference. 4. Being compared with age group, early attrition pattern showed decreasing tendency and late attrition pattern showed increasing tendency by aging.

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STUDY ON THE DEGREE OF TEETH ATTRITION WITH AGE INCREASE OF THE KOREAN (한국인의 연영증가에 따른 치아교모도에 관한 연구)

  • Lee, Myung-Chong
    • The journal of the Korean dental association
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    • v.10 no.7
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    • pp.445-450
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    • 1972
  • The author collected 93 male stone model and 93 female stone model of upper and lower jaw of the koreans as samples and studied the degree of attrition with age increase. Determining the degree of attrition, each normal cusp were given 40 points and calibrated into percentage. The percentage score were examined and analized, and came to the following conclusions. 1) Increased age were found graudually higher the degree of attrition at 10 to 20 age,. The degree of attrition presented localized disappearance of marginal-ridges and marginal grooves. At 30 up to 40 age, about 40 to 50% of the degree of attrition were found gradually on cusp ridges and grooves At 50 to 60 age, it was found about 70 to 80% of attrition. 2) Male score was slightly higher than female. 3) There was no significant difference between male and female score.

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Attrition Characteristics of Korean Antracite Ash in Fluidized Bed Combustors (유동층 연소로에서 국내탄 회재의 마모 특성)

  • Lee, See Hoon;Kim, Sang Done;Kim, Jae Sung;Lee, Jong Min
    • Applied Chemistry for Engineering
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    • v.17 no.5
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    • pp.547-551
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    • 2006
  • In the reactor following the American standard test method (ASTM) D5757-95 and lab-scale fluidized bed combustor, the attrition characteristics of sand and ash of Korean anthracite were investigated. The attrition characteristics, such as particle size distribution of fly ash, attrition rate, and attrition ratio etc, were studied with variation of gas velocities. The particle attrition of ash was more active than sand which was generally used as a fluidized material and also the attrition index of ash taken by ASTM D5757-95 was 5 times higher than that of sand. The formation of fine particles continuously occurred due to particle attrition with increasing gas velocities. The following equation has been suggested for attrition rate of ash. $$\frac{dW}{dt}=-3.18{\times}10^{-7}(U-U_{mf})W$$.

The Effect of Fluidized-Bed Variables on Attrition of Solid Particles (유동층 공정변수의 고체입자 마모에 미치는 영향)

  • Moon, Young-Sub;Yi, Chang-Keun;Son, Jae-Ek;Ryu, Chung-Keol;Choi, Jeong-Hoo
    • Applied Chemistry for Engineering
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    • v.16 no.5
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    • pp.603-608
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    • 2005
  • This study was conducted to investigate particle attrition characteristics in a gas desulfurization using zinc titanate sorbent in a 0.035 m i.d. by 1.34 m height gas fluidized bed reactor. Gas jetting from the distributor and bubbling in the gas fluidized bed were found to be the main causes of particle attrition. The experiment was carried out under a slow attrition rate condition to compare the performance of the batch reactor to that of a continuous reactor. The attrition index (AI) and corrected attrition index (CAI) were measured at various the gas velocity, temperature, pressure, and bed weight, in the gas fluidized bed, during the dexulfurization process. The AI (5) and CAI (5) decreased as the bed weight increased. Particle destruction occurred when the particles started to experience physical fatigue under specific impacts over several iterations. AI (5) and CAI (5) also increased as relative humidity, gas velocity and pressure increased, and as temperature decreased. Particle attrition was mainly affected by gas jetting from the distributor, and abrasion resulted in smaller particles than fragmentation did.