• 대한치과보철학회지
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• 제41권5호
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• pp.565-581
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• 2003

Statement of problem : A scientific examination and understanding of overall aspects of the natural dentition is the first step involved in making a satisfactory selection in the shade of an aesthetic prosthesis. Proper natural shade selection of the prosthetic restoration that is in harmony with the remaining dentition is as important aesthetically, as harmony of form and function in the anterior dentition. Clinically, the most commonly applied method of shade selection has been visual, but because of the subjective nature inherent to this method, shade selection results are variable and can be influenced by such factors as the technician, the type of shade guide used, and the type and intensity of the lighting. Purpose : The purpose of this study was to develop a more objective and scientific approach to examining and understanding the shade of teeth, which has in turn lead to the development of a number of shade analysis devices that present a more objective method of shade analysis. Material and Method : In this study, the shades of healthy anterior teeth were examined and analyzed using the recently developed digital shade analysis of the $ShadeScan^{TM}$ System. The study examined 80 individuals in their twenties, 40 males and 40 females, presenting 6 healthy, unrestored maxillary anterior teeth. Tooth brushing and oral prophylaxis were performed prior to evaluation. The ShadeScan handpiece was used to acquire images of the 6 maxillary anterior teeth. These images were analyzed using the Vita/Classical mode of the $ShadeScan^{TM}$ Software, and shade maps of each tooth were acquired and divided into cervical, middle, and incisal thirds. The shade distribution of each third, left and right symmetry, and gender differences were investigated and analyzed. Results : The results of the study are as follows : 1. An overwhelming majority of the examined teeth were found to possess shades belong to Group A, with the greatest variations occurring at the middle and cervical thirds of the maxillary central and lateral incisors, in both male and female subjects. 2. Canines of both male and female subjects showed left and right symmetry with uniform shade distribution of A4 and C4, while the lateral and central incisors showed left-right symmetry of the incisal 1/3 with a uniform shade distribution of A2 and A3 shades 3. No significant differences in shade distribution were seen between genders in maxillary canines, whereas maxillary central and lateral incisors showed differences at the middle and cervical thirds between male and female subjects The results of this study show that with the exception of maxillary canines, maxillary anterior teeth display a diverse shade distribution as well as gender differences. Conclusion : Clinically, when making a shade selection using the existing shade guide, one must consider the fact that even a single tooth consists of a variety of shades. The results of this study show that when selecting a shade from a number of groups is difficult, shades from A group are the most consistent with the natural shade or maxillary anterior teeth.

• 대한치과보철학회지
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• 제29권2호
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• pp.147-160
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• 1991

The purpose of this study was to examine, by the method of finite element analysis, how implant geometry with or without connection between natural tooth and osseointegrated abutments affected the stress distribution in surrounding bone and osseointegrated prosthesis. The mandibular first and second molars were removed and the two osseointegrated implants were placed in the first and second molar sites. Stress analysis induced by prostheses with connection(Model A)or without connection(Model B) between natural tooth(second bicuspid) and two osseointegrated abutments(first molar and second molar) was performed under vertical point load(Load P1) or distributed point load(Load P2). The results were as follows; 1. Under vertical point load, mesial tilting was shown in both Model A and Model B and inferior displacement of Model A was greater than that of Model B in the second bicuspid. 2. Under vortical point load, the first and second molars showed mesial tilting in both Model A and Model B, and inferior displacement of them was similar in Model A and Model B and was less than that of the second bicuspid. 3. Under distributed point load, mesial displacement was shown in Model A and Model B and inferior displacement of Model A was less than that of Model B in the second bicuspid. 4. Under distributed point load, mesial tilting was shown and inferior displacement of Model A was similar to that of Model B in the first and second molars. 5. In Model A under vertical point load, high stress was concentrated in the corneal portion of first molar and distributed throughout the second molar and the second bicuspid, and the stress distribution of the second molar was greater than that of the second bicuspid. 6. In Model B under vertical point load, high stress was concentrated in the coronal and mesio-cervical portion of the first molar. 7. In Model A under distributed point load, high stress was concentrated in the mesio-cervical portion of the first molar and evenly distributed throughout the second molar and the second bicuspid. 8. In Model B under distributed point load, high stress was concentrated in the disto-cervical portion of the second bicuspid and evenly distributed throughout the first and second molars.

• 대한치과교정학회지
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• 제33권3호
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• pp.157-167
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• 2003

본 연구는 치아크기와 악골크기의 상관관계를 살펴보고자 교정치료경험이 없고 교합이 양호한 87명 (남자49명, 여자38명)의 치아경석고모형과 두부방사선사진을 평가하였다. 치아크기는 치아의 근원심 최대폭경을 디지털 버니어 캘리퍼스를 이용하여 반복 측정하였고 악골의 크기는 기존의 여러 두부방사선계측법에서 이용된 악골의 선계측치를 반복 측정하였다. 치아와 악골크기 모두 성별에 따라 다르게 측정하였다. 치아크기와 악골크기 사이의 상관관계를 알아보기 위해 피어슨 상관관계분석을 실시하였다. 결과는 다음과 같다. 1.성별에 따라 두 군으로 나뒀을 경우 악골크기와 치아크기가 두 군에서 유의성 있게 다르게 나타났다. 2.남자군에서는 상악골과 상악치아 크기는 유의한 상관관계를 보이지만 여자군에서는 상악골과 상악치아 크기는 거의 상관관계를 보이지 않았다. 3. 남자군에서는 상악골의 크기를 나타내는 PTM vert-ANS vert (FH plane)과 PTM vert-A vert (palatal plane)는 모든 상악치아와 유의성 있는 상관관계를 보였으며 상악중절치는 상악골에 관계된 모든 계측치들과 유의성 있는 상관관계를 보였다. 4. 남여 모두에서 하악골의 크기를 나타내는 B vert- Point J vert (mandibular plane)는 하악치아와 유의성 있는 상관관계를 보였다. 위의 결과에서 자연적으로 나타나는 정상교합에서 치아와 악골크기는 상관관계가 낮거나 거의 없음을 알 수 있다.

• 대한치과보철학회지
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• 제50권1호
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• pp.10-20
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• 2012

연구 목적: 이 연구의 목적은 텔레스코픽 크라운 하악 임플란트 지지 피개의치와 치아 지지 피개의치에서 지대치의 수와 위치에 따른 응력 분산을 비교하기 위함이다. 연구 재료 및 방법: 본 연구에서는 임플란트를 4개 식립하고 임플란트 지지 피개의치로 설계하였고, 식립 위치를 견치와 소구치 부위에 위치 별로 3개 또는 2개존재시를 실험군으로 설정하였다. 자연치아를 갖는 경우도 견치와 제2소구치 4개를 가진 경우를 대조군으로 설정하고 부위별로 3개 또는 2개를 가지는 경우를 실험군으로 설정하였다. ANSYS Version 10.1(Swanson, Inc., USA)로 분석하였다. 결과: 악골내 응력의 경우, 전반적으로 임플란트(IM)로만 구성된 경우가 치아(TH)로만 구성된 경우에 비해 응력이 크게 발생하였다. 상부구조의 경우, 치아군(TH)과 임플란트군(IM) 사이의 차이는 크게 없었으며 편측 견치와 제2소구치에 지대치 또는 임플란트가 위치하는 경우 가장 큰 응력이 나타났고 바(bar)에서 발생된 응력이 임플란트와 치아에서 발생되는 응력에 비해 상대적으로 훨씬 크게 발생하였다. 지대치와 임플란트의 경우, 치아군(TH)이 임플란트군(IM)보다 응력이 작게 발생하였다. 결론: 본 연구의 결과로부터 지대치(임플란트 또는 치아)를 설정할 때는 하중작용점과 지대치 사이의 거리가 너무 길어지지 않도록 지대치의 수와 위치를 확보해야 하며 소구치 자리에 지대치를 확보하는 것이 유리하다. 앞으로, 실제 임상에 적용하였을 경우, 임플란트 및 자연치아와 악골에 미치는 결과에 대한 연구가 더 필요할 것으로 생각된다.

• 대한소아치과학회지
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• 제46권1호
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• pp.64-75
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• 2019

이 연구의 목적은 임상에서 많이 사용되고 있는 3종의 기성 크라운 즉, 레진관, 레진피복 금속관, 지르코니아 크라운의 크기와 형태를 3차원적으로 계측하여 자연치와 비교함으로써 기성 크라운의 크기 선택과 치질 삭제량에 대한 지침을 얻고자 하는데 있다. 300개의 유전치 석고모델과 3종의 기성 크라운을 대상으로 3D 스캐너와 컴퓨터 이미지 프로그램으로 3차원적 모델을 만들었다. 3차원 모델에서 치관의 근원심 너비, 치관 높이, 치관 ratio, 순면의 곡률반경 등 4가지 평가 척도에 의해 각 기성 크라운별로 한국인 자연치 표준모형과 가장 유사한 형태를 고르고 이를 기준으로 치질 삭제량을 비교, 평가하였다. 유중절치의 경우 기성 크라운별로 레진피복 금속관은 2번, 지르코니아 크라운은 1번, 레진관은 2번이, 유측절치의 경우 레진피복 금속관은 3번, 지르코니아 크라운은 2번, 레진관은 3번이 가장 유사한 형태를 보였다. 치아 삭제량은 상악 유중절치와 유측절치에서 같은 양상을 보였다. 절단연에서는 지르코니아 크라운의 삭제량이 가장 컸다. 인접면은 지르코니아 크라운과 레진관이 비슷한 삭제량을 보였으며 레진피복 금속관에 비해서 컸다. 순면 역시 지르코니아 크라운이 유중절치와 유측절치에서 삭제량이 가장 컸다. 설면의 경우 순면에 비해 전체적으로 삭제량이 적었으며 3종류의 기성 크라운 간에 삭제량 차이도 크지 않았다. 크라운의 형태를 비교하기 위한 4가지 평가 척도 중 치관의 근원심 너비가 기성 크라운의 크기를 선택하는데 가장 중요한 척도로 나타났다.

• 대한치과기공학회지
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• 제2권1호
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• pp.35-38
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• 1980

이 기술은 레진(acrylic resin) 또는 의과용 도재(dental porcelain)에 의한 치아 색깔의 전장부위를 갖고 있는 금속구치 block(metal posterior tooth block)의 개조에 대한 기술의 일면이다. 이 기술은 모든 가철식 보철물(removable dental restoration)에 적용할 수 있으며 특히 자연치열(natural dentition) 대합치에 가철식 국부의치(removable partial denture)를 갖고 있는 만성 이갈음 환자(chronic bruxing patient)에 적용할 수 있다.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1842-1850
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• 2017

Reducing the noise and vibration of the BLDC motors is very essential for some special applications. In this paper, a new structural design is introduced to increase the natural frequencies of the stator in BLDC motors as increasing the natural frequencies can reduce the severe effects of the structural resonances, including high levels of noise and vibration. The design is based on placing a single hole on definite regions at the stator cross sectional area (each region contains one tooth and its upper parts in the stator yoke) in an optimum way by which the natural frequencies at different modes are shifted to the higher values. The optimum diameter and locations for the holes are extracted by the Response Surface Methodology (RSM) and the modal analyses in the iterative process are done by Finite Element Method (FEM). Moreover, the motor performance by the optimum stator structure is analyzed by FEM and compared with the prototype motor. Preventing the stator magnetic saturation and the motor cogging torque enhancement are the two constraints of the optimization problem. The optimal structural design method is applied experimentally and the validity of the design method is confirmed by the simulated and experimental results.

• 한국동물위생학회지
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• 제30권3호
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• pp.459-466
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• 2007

The Korean Musk deer (Moschus Moschiferus) is endangered due to heavy hunting and Massive destructions of natural habitat. They are included in CITES appendix II. In addition they are designated as a precious natural product in 1968 and listed as endangered species by the Government and Cultural Heritage Administration. At present, the number of musk deer in Korea is smaller than minimum viable population. Without increment of the population size, natural restoration is impossible. It is necessary to develop the artificial growth and re-enforcement methods in order to conservation Korean musk deer. Furthermore, It is necessary to ensure that we have an adequate individual group for artificial growth and re-enforcement. To ensure that we have an adequate individual group, it is necessary to know ecology of musk deer. This study is conducted to confirm and investigate of habitat of musk deer in order to capture individual musk deer. we investigated, confirmed habitats, found traces and captured using trap and decoy. Captured musk deer is male and 5.5 kg, this have canine tooth of 1.5cm, is estimated 15 months old. After capture, we measured each parts of body and tested to research of parasite infection. Strongyloides papillous was founded in the feces. It is essential to get healthy individual and establish of artificial growth technique.

• Molecules and Cells
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• 제20권3호
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• pp.325-330
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• 2005

Ancient cattle bones were excavated from archaeological sites in Jeju, Korea. We used molecular genetic techniques to identify the species and establish its relationship to extant cattle breeds. Ancient DNA was extracted from four sources: a humerus (Gonae site, A.D. 700-800), two fragments of radius, and a tooth (Kwakji site, A.D. 0-900). The mitochondrial DNA (mtDNA) D-loop regions were cloned, sequenced, and compared with previously reported sequences of various cattle breeds (9 Asian, 8 European, and 3 African). The results revealed that these bones were of the breed, Bos taurus, and a phylogenetic tree indicated that the four cattle bones formed a monophyletic group with Jeju native black cattle. However, the patterns of sequence variation and reports from archaeological sites suggest that a few wild cattle, with a different maternal lineage, may have existed on Jeju Island. Our results will contribute to further studies of the origin of Jeju native cattle and the possible existence of local wild cattle.

• 대한치과의사협회지
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• 제58권1호
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• pp.45-49
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• 2019

Korean society is experiencing a very rapid change in population aging. Oral diseases, including dental caries and periodontal disease, are usually cumulative and make oral health worse with age. Preventing tooth loss through the prevention and treatment of caries and periodontal diseases are essential for retaining oral function later in life. This study aimed to identify the trend in oral health status among elderlies over 65 years old, using major oral health indicators of Health Plan 2020. The fifth, sixth, and seventh Korea National Health and Nutrition Examination Survey (KNHANES V, VI, VII) were used in the present study to estimate the number of remaining natural teeth, the rate of 20 or more natural teeth, the rate of chewing difficulty, and the rate of oral health check-up of elderly. The number of remaining natural teeth increased from 15.6 in 2010 to 17.1 in 2015, and the rate of 20 or more natural teeth also increased from 45.8% in 2010 to 53.7% in 2015. The rate of chewing difficulty was similar but declined a little from 44.3% in 2010 to 42.9% in 2017. Finally, the rate of oral health check-ups of the elderly increased significantly from 12.2% in 2010 to 21.1% in 2017.