• 한국해안·해양공학회논문집
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• 제22권6호
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• pp.397-404
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• 2010

테트라포드로 피복된 사석경사제를 대상으로 하여 설계파 조건, 피복층 마루폭 그리고 마루 여유고를 변화시켜 수리실험을 수행한 후, 대상 구조물의 월파 성능을 검토하며 그리고 널리 사용되고 있는 월파량 예측모형을 적용하여 수리실험 결과와 비교를 통해 예측모형들의 특성을 파악하였다. 사면경사와 주기는 월파량에 상당히 영향을 미치나, 피복층 마루폭의 변화에 따른 월파량의 차이는 미미한 편이다. Owen(1980)의 예측모형은 계측월파량과 비교하여 과대 예측하는 반면에, Van der Meer et al.(1998)의 예측모형은 비교적 급한 사면($cot{\alpha}$=1.5)에서만 과소 예측하는 경향이 있다. Besley(1999)와 Pedersen(1996)의 예측모형은 보다 폭이 넓은 피복층 마루폭을 가진 사면에서 계측월파량에 비교적 좋은 일치를 보여주나, 모든 실험조건에 대해서는 일반적으로 수정 Pedersen의 예측모형이 계측월파량에 가장 일치하는 결과를 나타낸다.

• Journal of Periodontal and Implant Science
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• 제36권2호
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• pp.461-471
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• 2006

In order to achieve a satisfactory esthetic result of periodontal surgery or implant in maxillary anterior area, periodontists must be aware of normal alveolar bone anatomy. The purpose of this study was to evaluate the relationship of alveolar bone morphology to tooth shape and form. 78(mean age : 25 yrs) periodontally healthy volunteers participated in this study. Two maxillary central incisor and one lateral incisor were selected to study. With minimal local anesthesia, gutta-percha cone inserted to labial gingival sulcus of selected teeth just after bone sounding with periodontal probe. Metal ball (4mm diameter) attached to palatal fossa of central incisor. Then, periapical radiograph was taken according to long cone paralleling technique. After film scan, labial alveolar bone profile reproduced along interproximal bone and apical ends of gutta-percha cones on computer screen. By utilizing computer program, the distance from height of interproximal bone to the labial bone crest in central incisor-central incisor and central incisor-lateral incisor area was measured and converted to real distance by using vertical length of metal ball on film. After measuring crown length & width of central incisor, the 10 individuals ranked lowest GW/L ratio (crown width/length ratio) and the 10 ranked highest were selected as having a long-narrow(group N), or a short-wide(group W) form of the central incisors. Means of the distance from height of interproximal bone to the labial bone crest of group N, W were calculated and compared by means of independent t-test. The results were as follows: 1. Mean distance from the height of the interproximal bone to the labial bone crest was $3.5{\pm}0.7mm$ between two central incisor, and $2.8{\pm}0.6mm$ between central and lateral incisor. 2. Mean GW/L ratio of group N was 0.57, and group W was 0.8. Mean distance from the height of the interproximal bone to the labial bone crest of group N was higher than group W in both measured area(measurements of group N, W were $3.9{\pm0.2mm$ and $3.5{\pm}0.2mm$ between two central incisor, $3.0{\pm}0.2mm$ and $2.8{\pm}0.2mm$ between central and lateral incisor), but there were no statistically significant differences when the groups were compared. Within the limits of the present study, there was a tendency that subjects with long-narrow teeth have more scalloped alveolar bone profile than subjects with short-wide teeth in upper anterior area, but no statistically significant differences were found.

• 대한치과교정학회지
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• 제37권3호
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• pp.212-219
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• 2007

현재 교정용 미니 임플란트의 식립부위에 대한 연구는 주로 구치부 치근사이 공간에 집중되어 왔으며, 연조직에 관한 연구는 부족하다. 본 연구의 목적은 하악골에서 전치부와 구치부의 치근사이 피질골과 연조직 두께를 측정하여 해부학적인 지도를 만들고, 한국인의 평균 부착치은의 폭경을 제시하는데 있다. 연구를 위하여 자원한 남자 15명, 여자 15명 총 30명을 대상으로 하였으며, 평균연령은 27세 3개월이었다. 구강 내 인상을 채득한 후 석고모형을 만들어 0.5 mm두께의 평판으로 스텐트를 제작하였다. 스텐트의 중절치에서 제1대구치까지 치근사이 치은변연을 연결한 선에 방사선 불투과성의 표식을 부착하고 구강 내에 장착한 후 3차원 CT 영상을 얻고, 각 치근사이 치조정 하방에서 2, 4, 6, 8 mm부위의 피질골 두께를 측정하였다. 연조직 두께는 스텐트의 각 치근사이 치조정 하방에서 2, 4, 6, 8 mm부위에 구멍을 뚫고 구강 내에서 근관치료용 파일을 연조직에 통과시켜 측정하였다. 석고모형 상에서 중절치에서 제1대구치까지 각 치근중앙 부위에서 부착치은의 폭경을 측정하였다. 연구결과 하악골에서 전체대상자의 평균 피질골 두께는 $1.33{\pm}0.38mm$이었으며 전치부에서 구치부로 갈수록 두꺼워지고, 평균 연조직 두께는 $1.49{\pm}0.54mm$이었으며 치근단 쪽으로 내려가면서 두께가 변하지 않았다. 평균 전체 두께는 $2.82{\pm}0.70mm$이었으며 전치부에서 구치부로 갈수록 두꺼워졌다. 부착치은의 폭경은 전치부가 구치부보다 넓었다. 이상의 결과는 피질골과 연조직 두께, 부착치은의 폭경을 고려하여 미니 임플란트의 식립부위를 결정하는 것이 필요함을 시사하였다.

• 센서학회지
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• 제18권3호
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• pp.239-244
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• 2009

We fabricated nano-templates by low temperature BCP(block copolymer) process at 180 $^{\circ}C$, then we deposited 10 nm-thick $TiO_2$ layers with ALD(atomic layer deposition) at low temperature of 150 $^{\circ}C$. Through FE-SEM analysis, we confirmed the successful formation of the groove-type(width of crest : 30 nm, width of trough : 18 nm) and the cylinder-type(diameter : 10 nm, distance between hole : 25 nm) templates. Moreover, after $TiO_2$-ALD processing, we confirmed the deposition of the uniform nano layers of $TiO_2$ on the nano-templates. Through AFM analysis, the pitches of the crest-through(in groove-type) and hole-hole(in cylinder-type) were the same before and after $TiO_2$-ALD processing. In addition, we indirectly determined the existence of the uniform $TiO_2$ layers on nano-templates as the surface roughness decreased drastically. We successfully fabricated nano-template at low temperature and confirmed that the three-dimensional nano-structure for sensor application could be achieved by $TiO_2$-ALD processing at extremely low temperature of 150 $^{\circ}C$.

• 한국구조물진단유지관리공학회 논문집
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• 제7권3호
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• pp.175-181
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• 2003

본 논문에서는 상향 침투시험기를 이용하여 3가지 시료에 대하여 상향 투수시험을 수행하였고, 이를 통하여 한계속도, 한계동수경사, 투수계수 등을 산정하여 기존의 세굴 검토 방법에 대한 신뢰성을 파악하였다. 또한 세굴 설계인자에 대하여 FEM Program인 Plaxis를 이용하여 민감도 분석을 수행하였다. 민감도 분석결과 제방 하부의 출구부 동수 경사에 가장 영향을 많이 미치는 인자는 중심코어의 높이로 나타났다. 또한 제방의 구배와 뚝마루 폭이 중심코어의 높이 다음으로 세굴에 영향성이 큰 것으로 나타났다. 그러나 중심코어의 뚝마루폭은 출구부의 동수경사 변화에 영향이 적은 것으로 나타났다. 이러한 민감도 분석결과를 이용하여 설계시 동수경사가 기준 동수경사보다 크게 나타날 경우 민감도 변화가 큰 설계인자를 변경하여 경제적이고 보다 손쉬운 출구부 동수경사 저감이 가능하리라 판단된다.

• 대한치과교정학회지
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• 제48권6호
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• pp.349-356
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• 2018

Objective: This study was performed to investigate the alveolar bone of lower incisors in skeletal Class III adults of different vertical facial patterns and to compare it with that of Class I adults using cone-beam computed tomography (CBCT) images. Methods: CBCT images of 90 skeletal Class III and 29 Class I patients were evaluated. Class III subjects were divided by mandibular plane angle: high (SN-MP > $38.0^{\circ}$), normal ($30.0^{\circ}$ < SN-MP < $37.0^{\circ}$), and low (SN-MP < $28.0^{\circ}$) groups. Buccolingual alveolar bone thickness was measured using CBCT images of mandibular incisors at alveolar crest and 3, 6, and 9 mm apical levels. Linear mixed model, Bonferroni post-hoc test, and Pearson correlation analysis were used for statistical significance. Results: Buccolingual alveolar bone in Class III high, normal and low angle subjects was not significantly different at alveolar crest and 3 mm apical level while lingual bone was thicker at 6 and 9 mm apical levels than on buccal side. Class III high angle group had thinner alveolar bone at all levels except at buccal alveolar crest and 9 mm apical level on lingual side compared to the Class I group. Class III high angle group showed thinner alveolar bone than the Class III normal or low angle groups in most regions. Mandibular plane angle showed negative correlations with mandibular anterior alveolar bone thickness. Conclusions: Skeletal Class III subjects with high mandibular plane angles showed thinner mandibular alveolar bone in most areas compared to normal or low angle subjects. Mandibular plane angle was negatively correlated with buccolingual alveolar bone thickness.

• Journal of Periodontal and Implant Science
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• 제50권1호
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• pp.28-37
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• 2020

Purpose: The aim of our study was to determine the prevalence and degree of lingual concavities in the first molar region of the mandible to reduce the risk of perforating the lingual cortical bone during dental implant insertion. Methods: A total of 163 suitable cross-sectional cone-beam computed tomography images of edentulous mandibular first molar regions were evaluated. The mandibular morphology was classified as a U-configuration (undercut), a P-configuration (parallel), or a C-configuration (convex), depending on the shape of the alveolar ridge. The characteristics of lingual concavities, including their depth, angle, vertical location, and additional parameters, were measured. Results: Lingual undercuts had a prevalence of 32.5% in the first molar region. The mean concavity angle was 63.34°±8.26°, and the mean linear concavity depth (LCD) was 3.03±0.99 mm. The mean vertical distances of point P from the alveolar crest (Vc) and from the inferior mandibular border were 9.39±3.39 and 16.25±2.44, respectively. Men displayed a larger vertical height from the alveolar crest to 2 mm coronal to the inferior alveolar nerve (Vcb) and a wider LCD than women (P<0.05). Negative correlations were found between age and buccolingual width at 2 mm apical to the alveolar crest, between age and Vcb, between age and Vc, and between age and LCD (P<0.05). Conclusions: The prevalence of lingual concavities was 32.5% in this study. Age and gender had statistically significant effects on the lingual morphology. The risk of lingual perforation was higher in young men than in the other groups analyzed.

• Imaging Science in Dentistry
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• 제51권2호
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• pp.155-165
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• 2021

Purpose: This study aimed to evaluate changes of the alveolar bone and interdental bone septum of the mandibular incisors through cone-beam computed tomography (CBCT) after orthodontic treatment of mandibular dental crowding without dental extraction. Materials and Methods: The sample consisted of 64 CBCT images(32 pre-treatment and 32 post-treatment) from 32 adult patients with class I malocclusion and an average age of 23.0±3.9 years. The width and height of the alveolar bone and interdental septum, the distance between the cementoenamel junction (CEJ) and the facial and lingual bone crests, and the inclination of the mandibular incisors were measured. Results: The distance between the CEJ and the marginal bone crest on the facial side increased significantly (P<0.05). An increased distance between the CEJ and the bone crest on the facial and lingual sides showed a correlation with the irregularity index (P<0.05); however, no significant association was observed with increasing mandibular incisor inclination (P>0.05). The change in the distance between the CEJ and the marginal bone crest on the facial side was correlated significantly with bone septum height(P<0.05). Conclusion: Bone dehiscence developed during the treatment of crowding without extraction only on the incisors' facial side. Increasing proclination of the mandibular incisor was not correlated with bone dehiscence. The degree of dental crowding assessed through the irregularity index was associated with the risk of developing bone dehiscence. The interdental septum reflected facial marginal bone loss in the mandibular incisors.

• Ocean Systems Engineering
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• 제11권1호
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• pp.83-97
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• 2021

The submerged U-shape breakwater interaction with the solitary wave is simulated by the Boussinesq equations using the finite-difference scheme. The wave reflection, transmission, and dissipation (RTD) coefficients are used to investigate the U-shape breakwater's performance for different crest width, Lc1, and indent breakwater height, du. The results show that the submerged breakwater performance for a set of U-shape breakwater with the same cross-section area is related to the length of submerged breakwater crest, Lc1, and the distance between the crests, Lc2 (or the height of du). The breakwater has the maximum performance when the crest length is larger, and at the same time, the distance between them increases. Changing the Lc1 and du of the U-shape breakwaters result in a significant change in the RTD coefficients. Comparison of the U-shape breakwater, having the best performance, with the averaged RTD values shows that the transmission coefficients, Kt, has a better performance of up to 4% in comparison to other breakwaters. Also, the reflection coefficients KR and the diffusion coefficients, Kd shows a better performance of about 30% and 55% on average, respectively. However, the model governing equations are non-dissipative. The non-energy conserving of the transmission and reflection coefficients due to wave and breakwater interaction results in dissipation type contribution. The U-shape breakwater with the best performance is compared with the rectangular breakwater with the same cross-section area to investigate the economic advantages of the U-shape breakwater. The transmission coefficients, Kt, of the U-shape breakwater shows a better performance of 5% higher than the rectangular one. The reflection coefficient, KR, is 60% lower for U-shape in comparison to rectangular one; however, the diffusion coefficients, Kd, of U-shape breakwater is 35% higher than the rectangular breakwater. Therefore, we could say that the U-shape breakwater has a better performance than the rectangular one.

• 대한토목학회논문집
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• 제40권5호
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• pp.485-496
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• 2020

잠제와 인공리프와 같은 수중구조물은 연안역의 침식 등의 대책으로 일반적으로 사용되고 있다. 본 연구에서는 Tetrapod로 제체를 형성한 투과형 수중구조물을 대상으로 파랑의 전달에 대한 2차원 수리실험을 수행하였다. 수리실험은 서로 다른 상대여유수심, 상대여유고, 상대상단폭 및 파형경사 등을 적용하여 수행되었다. 수리실험결과를 이용하여 투과형 수중구조물에 의한 파고전달계수 산정식을 제안하였다. 제안된 경험식은 파고전달계수를 충분한 정도로 예측함을 확인하였으며, 기존 경험식을 개선하였다.