• 대한치과교정학회지
• /
• 제53권2호
• /
• pp.106-115
• /
• 2023

Objective: To evaluate the null hypothesis that there is no difference in a set of clinical predictors of potentially impacted canines between low-risk patients with and without displaced canines. Methods: The normal canine position group consisted of 30 patients with 60 normally erupting canines ranked in sector I (age, 9.30 ± 0.94 years). The displaced canine group comprised 30 patients with 41 potentially impacted canines ranked in sectors II to IV (age, 9.46 ± 0.78 years). Maxillary lateral incisor crown angulation, inclination, rotation, width, height, and shape, as well as palatal depth, arch length, width, and perimeter composed a set of clinical predictors, which were evaluated on digital dental casts. Statistical analyses consisted of group comparisons and variable correlations (p < 0.05). Results: There was a significant association between sex and mesially displaced canines. Unilateral canine displacement was more prevalent than bilateral displacement. The crown of the maxillary lateral incisors was significantly angulated more mesially and rotated mesiolabially in low-risk patients with displaced canines, who also had a shallower palate and shorter anterior dental arch length. Lateral incisor crown angulation and rotation, as well as palatal depth and arch length, were significantly correlated with the canine displacement severity. Conclusions: The null hypothesis was rejected. Maxillary lateral incisor angulation inconsistent with the "ugly duckling" stage as well as a shallow palate and short arch length are clinical predictors that can significantly contribute to the early screening of ectopic canines in low-risk patients.

• 대한치과의사협회지
• /
• 제10권3호
• /
• pp.155-158
• /
• 1972

As a factor of dentistry, the form of the tooth especially the size plays an important part. And in orthodontics the relation between the tooth size, arch length and the basal arch is regarded important, and it is closely related to the extraction and retension probolem in treatment planning. The auther's study of the mesio-distal crown diameters of permanent teeth, width and length of the dental arch and basal arch from the cast of 50 men and 53 women who could be measured clerly, among 102 men and 107 women regarded as the normal occlusion showed the followings. 1. Table 1 and table 2 showed the measurement of the mesio-distal maximum width of the permanent teeth, width and length of the dental arch and basal arch of the upper and lower dentitions. 2. Men's mesio-distal width of the teeth, arch length and arch width of the upper and the lower dentition, basal arch width and basal arch length are larger than those of wonen's 3. We compared the Koreans with the American white. Upper central incisors, upper first molars and lower second premolars of the latter were larger than those of the former. And the Koreans's rest tooth of the rest were comparatively larger.

• 한국환경생태학회지
• /
• 제16권1호
• /
• pp.87-93
• /
• 2002

귀화식물인 가중나무는 도시지역에서 많이 발견된다. 그 주된 이유는 유.무성 생식이 잘 되기 때문이다. 종자의 확산과 맹아 출현에 의해 도시 서식지 내에서 쉽게 군락을 형성한다. 그러므로 가중나무의 종자의 확산과 발아분포 특성을 조사하는 것은 도시녹지 관리에 중요하다. 가중나무의 종자 확산 및 실생묘의 분포는 다음과 같이 조사되었다. 남산과 같이 환경조건이 최상일 때는 350개체, 퇴계원사거리 경우 50개체 정도가 발아해서 자란다. 이러한 종자는 풍향의 영향과 지형적 특성에 따라 확산 분포되는 경향이 있다. 조사대상지는 종자가 떨어지는 늦가을에서 봄까지 주로 북서풍이 불고 있으므로 남쪽으로 많이 비산 되었으며, 경사지인 퇴계원사 거리에서는 경사지의 아래쪽에 주로 분포하였다. 종자 발아에 의한 실생묘의 분포는 모수(母樹)의 수관폭과 비교하였을 때, 수관폭 내에 떨어지는 경우보다 수관폭 외곽에 떨어지는 경향이 있으며, 조사지역에서는 수관폭의 최대 7.5배까지 실생묘가 분포하였다. 주로 수관 폭의 2~4배 지점(20M 이내에 75% 분포)에서 군생을 나타냈다. 가중나무 종자 발아에 의한 실생묘 분포 확산으로 볼 때, 가중나무는 도시의 열악한 환경에서라도 급격한 개체수 증가가 있을 수 있으며, 이는 도시 토양의 보호라는 측면과 가중나무가 타수종과 경쟁에서 성공함으로 종 다양성 감소라는 측면을 같이 고려하여 관리방안을 모색해야 할 것으로 판단된다.

• 구강회복응용과학지
• /
• 제36권4호
• /
• pp.262-271
• /
• 2020

변연골 하방으로까지 파절선이 연장된 치아를 수복하기 위해 파절선의 노출 및 생물학적 폭경의 재확립을 위한 삭제형 골수술을 동반한 외과적 치관 연장술을 고려해 볼 수 있다. 그러나 이 술식은 특히 전치부에서 심미성을 훼손시킬 수 있다. 따라서 지지골과 치은을 희생시키지 않으면서 파절선을 치조와 하방에서 상방으로 위치 시킬 수 있는 교정적 정출술이 권장된다. 이 술식은 생물학적 폭경의 재확립과 더불어 수복물을 건전한 치아 구조에 위치할 수 있도록 해 준다. 또 다른 대안으로, 교정적 정출술 보다 방법이 간단하며 시간이 적게 소요되고 한번의 술식만으로 정출이 완료되는 외과적 정출술도 고려해 볼 수 있다. 외과적 정출술을 이용할 경우 구강내 교정 장치를 위치시키고 조정하기 위해 환자가 치과에 여러번 방문할 필요가 없다. 본 연구에서는 상악 중절치에서 치관-치근 파절이 발생한 경우 교정적 정출술 또는 외과적 정출술을 통한 다각적 방법을 병용함으로써 성공적으로 수복한 증례를 보고하고자 한다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 춘계학술대회 논문집
• /
• pp.70-73
• /
• 2004

The approach in this thesis is for prediction of deformed strip profile in hot rolling mill. This approach shows how to make an expression as a mathematical form in predicting strip profile. This approach is based on the velocity field, shear stress and material flow on the strip edge along width direction and lateral displacement and stress along width are analytically calculated. Roll force is calculated in each section and then combined together to show roll force distribution along width. All the assumptions to make equation form for this approach are supported by FEM simulation result and the result of model is verified by FEM result. So, this model will supply very useful tool to the researcher and engineers which takes less time and has similar accuracy in predicting roll force profile comparing to FEM simulation. This model has to be combined with deformed roll profile model, which include thermal crown prediction and wear prediction model to predict deformed strip profile.

• 대한치과교정학회지
• /
• 제21권3호
• /
• pp.481-493
• /
• 1991

The purpose of this study was to obtain the norm of the crown shape (tip, torque, in/out) and arch form, and to provide basic data for fabricating straight wire bracket and ideal arch wire for Korean. 100 subjects aged from 17 to 26 (50 females, 50 males) were selected with a normal occlusion. By measuring the size, angulation, inclination, arch width, facial prominance of the teeth and the molar offset, the following results were obtained. 1. Average, standard deviation, minimum, maximum of each measuring item for each teeth were obtained. 2. Intermolar width (${\underline{6}}$ to ${\underline{6}}$) of upper arch before occlusal surface cutting and intermolar width of upper arch (${\underline{6}}$ to ${\underline{6}}$, ${\underline{7}}$ to ${\underline{7}}$) after occlusal surface cutting showed statistical difference. There was no difference between sexes in any other measuring items. 3. Arch form and specification of straight wire bracket for Korean who have normal occlusion was obtained.

• 구강회복응용과학지
• /
• 제24권3호
• /
• pp.243-251
• /
• 2008

외상으로 치아가 파절되었거나 우식으로 인해 치질이 치조정 수준이나 그 하방까지 소실된 경우 특별한 치료가 동반되지 않는다면 만족스럽게 수복할 수 없다. 이럴 경우 발치 후 임플란트 식립이나 레진 접착 가공 의치, 고정성 가공 의치 등을 이용할 수 있는데 각각의 상황에 따라 여러 가지 제한이 따른다. 이를 극복하는 방법의 하나로 치아 정출술을 이용할 수 있는데, 치아 정출술이란 연조직 및 골 변화를 일으키는 약한 힘을 지속적으로 적용하여 치아를 치관 방향으로 이동시키는 교정 술식으로 치주 건강을 유지하면서 보철 수복을 가능하게 하는 술식이다. 본 증례는 상악 전치부 파절이 발생한 치아를 치아 정출 술식을 이용하여 효과적으로 수복할 수 있었기에 이를 보고하는 바이다.

• 한국산림과학회지
• /
• 제94권5호통권162호
• /
• pp.313-320
• /
• 2005

This study was performed in a 38-year-old Mongolian pine (Pinus sylvestris L. var. mongolica Litvin) plantation in northeast China. Data were collected from 5 sample trees with different canopy position ranging in DBH from 14.6 cm to 23.8 cm. Sawn speciments that included the biggest knot were taken from the stem below the living crown. Number and distribution of knots per whorl below the living crown were studied by relative height below living crown (RHBC). A linear model expressed as function of whorl age (AGE), whorl height ($H_k$) and the stem diameter at which the whorl was located ($D_k$) was developed to predict the knot diameter and angle. The number of annual rings in four periods and the width of respective zone alone stem were used as dependant variables to analyze the knot develop phases. In average, the number of years from branch birth to ceased forming rings was 7.8, the branches remained alive for 4.2 years without forming annual rings, and branches were occluded 14.4 years after their death. These results can provide abundance branch and knot information so as to describe current and past tree growth dynamic of Mongolian pine plantation.

• 소성∙가공
• /
• 제17권8호
• /
• pp.600-606
• /
• 2008

In closed-die hot forging, a billet is formed in dies such that the flow of metal from the die cavity is restricted. Some parts can be forged in a single set of dies, whilst others, due to shape complexity and material flow limitations, must be shaped in multi sets of dies. The purpose of a performing operation is to distribute the volume of the parts such that material flow in the finisher dies will be sound. This study focused on the design of preforms, flash thickness and land width by theoretical calculation and finite element analysis, to manufacture the super hot forging product, 70MC type piston crown used in marine engine. The optimal design of preforms by the finite element analysis and the design experiment achieves adequate metal distribution without any defects and guarantees the minimum forming load and fully filling of the cavity of the die for producing the large piston crown. The maximum loads obtained by finite element analysis are compared with the results of experiments. The loads of the analysis have good agreements with those of the experiment. Results obtained using DEFORM-2D enable the designer and manufacturer of super hot forging dies to be more efficient in this field.

• Journal of Periodontal and Implant Science
• /
• 제39권2호
• /
• pp.199-204
• /
• 2009

Purpose: Excessive gingival display and short clinical crowns due to altered passive eruptions are major concerns for a considerable number of patients visiting dental clinics. Altered passive eruptions could be corrected through various types of periodontal surgery conformable to a classification. 3 cases are reported here on the esthetic correction of altered passive eruption to evaluate results of crown lengthening procedure. Methods: Three patients whose major complaints were excessive gingival display and short teeth were picked out for this case study. Before treatment, clinical and radiological exam was performed to choose type of surgery. Thickness and width of keratinized gingiva was measured in all three patients then they were treated by surgical methods including flap operation and depigmentation under subsequent diagnosis. Results: Uneventful healing and stable gingival margin were observed in all three patients except recurrence of gingival pigmentation of one patient. Conclusions: The treatment of altered passive eruption requires precise diagnostic procedure and could achieve better esthetic outcomes when it is accompanied by other orthodontic and orthognathic treatment.