평지 전통마을 갈림길의 중심각과 곡률반경에 관한 연구

김윤하,안계복 한국조경학회 2000 韓國造景學會誌 Vol.28 No.2

The purpose of this study is to identify relationships between a central angle and a radius of curvature of divided roads in flat terrain of traditional villages, suggesting layout criteria for traditional villages: Nak-an, Sung-Eup, Ha-Whe. This study is sought to find the optimum model through the various SAS regression analyses. a regression analysis of this data was adopted to induce the relationship formula between a central angle of curve and a radius of curvature. Results of this study are as follows: 1) Most of the divided roads in traditional villages have a complex curve rather than a simple curve. 2) A central angle of curve has ranged from 11$^{\circ}$to 127$^{\circ}$, with a mean degree of 63.9. 3) In the lower level of central angle(11-40$^{\circ}$), the branch roads have distributed with a high frequency, but with a low frequency in the higher level of central angle(90-140$^{\circ}$). 4) A radius of curvature in the divided roads has ranged from 0.9m to 59.6, but half of the roads have concentrated on 1-6m of the curvature. 5) Compared to the result of hilly villages in previous study(Ahn, 1999), value of central angels in flat villages is lower than that of hilly villages, while a mean value of the curvature is higher than that of hilly villages. 6) A Non-linear regression analysis, resulting from the SAS application, was useful method to induce a relationship formula between a central angle and a radius of curvature in the branch roads. Our study's formula is as follow: R=100.3*EXP(-0.06*$\delta$)+3.91. 7) Our study model has less error than that of the Kishizuka's method, being applicable to a broader range of the branch roads. 8) A minimum radius of curvature in our study has showed 3.9m, suggesting to reconsider applications of the Kishizuka's(5.8m) in the footpass design, In the study for this presupposition model the efficiency and utility of it can be estimated to grow large according to how much and how far it includes both extremes of data. This study is for the application to a design in future through the numerical formula of divided roads of various traditional villages. The studies from now on will be about the quasi-hilly quasi-hilly village and hilly village supplementing these factors more.

하악 대구치의 II형 근심 근관에서 치근단 부위의 만곡도 조사

윤혜림,이동균,황호길,Yun, Hye-Rim,Lee, Dong-Kyun,Hwang, Ho-Keel 대한치과보존학회 2012 Restorative Dentistry & Endodontics Vol.37 No.2

Objectives: The purpose of this study was to evaluate the buccolingual curvature at the apical one third in type II mesial canals of mandibular molars using the radius and angle of curvature. Materials and Methods: Total 100 mandibular molars were selected. Following an endodontic access in the teeth, their distal roots were removed. #15 H- or K-files (Dentsply Maillefer) were inserted into the mesiobuccal and mesiolingual canals of the teeth. Radiographs of the teeth were taken for the proximal view. Among them, type II canals were selected and divided into two subgroups, IIa and IIb. In type IIa, two separate canals merged into one canal before reaching the apex and in type IIb, two separate canals merged into one canal within the apical foramen. The radius and angle of curvature of specimens were examined. Results: In type II, mean radius of curvature in mesiolingual and mesiobuccal canals were 2.82 mm and 3.58 mm, respectively. The radius of the curvature of mesiolingual canals were significantly smaller than that of mesiobuccal canals in type II, and especially in type IIa. However, there were no statistically significant differences in radius of curvature between mesiobuccal and mesiolingual canals in type IIb and there were no significant differences in angle of curvature between type IIa and IIb. Conclusion: In this study, type II mesial canals of mandibular molars showed severe curvature in the proximal view. Especially, mesiolingual canals of type IIa had more abrupt curvature than mesiobuccal canals at the apical one third.

하악 대구치 Ⅱ형 근심 근관에서 치근단 부위의 만곡도 조사

윤혜림,이동균,황호길 大韓齒科保存學會 2012 Restorative Dentistry & Endodontics Vol.37 No.2

Objectives: The purpose of this study was to evaluate the buccolingual curvature at the apical one third in type Ⅱ mesial canals of mandibular molars using the radius and angle of curvature. Materials and Methods: Total 100 mandibular molars were selected. Following an endodonticaccess in the teeth, their distal roots were removed. #15 H- or K-files (Dentsply Maillefer) were inserted into the mesiobuccal and mesiolingual canals of the teeth. Radiographs of the teeth were taken for the proximal view. Among them, type Ⅱ canals were selected and divided into two subgroups, Ⅱa and Ⅱb. In type Ⅱa, two separate canals merged into one canal before reaching the apex and in type Ⅱb, two separate canals merged into one canal within the apical foramen. The radius and angle of curvature of specimens were examined. Results: In type Ⅱ, mean radius of curvature in mesiolingual and mesiobuccal canals were 2.82 mm and 3.58 mm, respectively. The radius of the curvature of mesiolingual canals were significantly smaller than that of mesiobuccal canals in type Ⅱ, and especially in type Ⅱa. However, there were no statistically significant differences in radius of curvature between mesiobuccal and mesiolingual canals in type Ⅱb and there were no significant differences in angle of curvature between type Ⅱa and Ⅱb. Conclusion: In this study, type Ⅱ mesial canals of mandibular molars showed severd curvature in the proximal view. Especially, mesiolingual canals of type Ⅱa had more abrupt curvature than mesiobuccal canals at the apical one third.

3D Printing Watermarking Method Based on Radius Curvature of 3D Triangle

PHAM NGOC GIAO,송하주,이석환,권기룡 한국멀티미디어학회 2017 멀티미디어학회논문지 Vol.20 No.12

Due to the fact that 3D printing is applied to many areas of life, 3D printing models are often used illegally without any permission from the original providers. This paper presents a novel watermarking algorithm for the copyright protection and ownership identification for 3D printing based on the radius curvature of 3D triangle. 3D triangles are extracted and classified into groups based on radius curvature by the clustering algorithm, and then the mean radius curvature of each group will be computed for watermark embedding. The watermark data is embedded to the groups of 3D triangle by changing the mean radius curvature of each group. In each group, we select a 3D triangle which has the nearest radius curvature with the changed mean radius curvature. Finally, we change the vertices of the selected facet according to the changed radius curvature has been embedded watermark. In experiments, the distance error between the original 3D printing model and the watermarked 3D printing model is approximate zero, and the Bit Error Rate is also very low. From experimental results, we verify that the proposed algorithm is invisible and robustness with geometric attacks rotation, scaling and translation.

곡면형 무동력 트레드밀의 곡률반경에 따른 주행특성 비교

김사엽(Sa-Yup Kim),노종련(Jong-Ryun Roh),형준호(Joon-Ho Hyeong) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

This investigation was undertaken to examine the biomechanical responses during walking and running on a Non-Motorized Curved Treadmill(NMCT). In this study, three different radius of curvature(2500㎜, 3000㎜, 3500㎜) of the NMCT were used to treadmill walking and running according to the three different speeds(70, 110, 170 step/min), and the speeds were controled by cadence. Subjects walked for three minutes with breaks between trials of speed and curvature to prevent fatigue. Twenty-seven retroreflective markers affixed to the full body were used to record three-dimensional kinematics(60Hz, Osprey, Motion Analysis Corp., USA) on the three different curvature of the NMCT with three different speeds. The step length was increased, and initial contact position on the treadmill belt has moved backward at lesser curvature. But the step width and deviation of center of body mass in the Anterior-Posterior direction were increased at the decreased radius of curvature, which mean the stability of walking and running on the NMCT was decreased. Consequently, the curvature needs larger radius to make stable walking and running, on the other hand, it needs lesser radius to walk and run easily on the NMCT.

A study on the optimum curvature for the curved monitor

최병화,이승배,이자은,홍성수,이장두,김성철 한국정보디스플레이학회 2015 Journal of information display Vol.16 No.4

Curved displays have been actively developed beyond the limits of the conventional flat displays. The curved displays are known to be advantageous for immersion, preferences, and viewing convenience. As such, it is necessary to conduct ergonomic studies on the curvature of the curved display. In this study, experiments were conducted to determine the optimal curvature of the curved display for six kinds of contents. The results of the experiments showed that the optimal curvature is 560.9 mm at the standard viewing distance of 600 mm, which can be considered an evidence that there is an intriguing correlation between the viewing distance and the display curvature. It is expected that the results of this study would improve the existing display products and would provide ergonomic guidelines for the users.

Effects of longitudinal and transverse curvatures on optimal design of shell footbridge

Shiming Liu,Bin Huang,Yi Min Xie 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.1

Shell bridges have attracted extensive interest in engineering research and practice. This paper aims to evaluate the effects of longitudinal and transverse curvatures on the optimal design of the shell bridge. For this purpose, a slant-legged steel shell footbridge with the same initial and target volumes of steel was chosen to build parametric geometric models with different curvature radii, and then topology optimization was carried out using the bi-directional evolutionary structural optimization (BESO) technique to obtain optimized designs with high structural stiffness. Furthermore, linear static analysis and eigenvalue analysis demonstrate that the displacement, von Mises effective stress, and the first-order vertical vibration frequency satisfied all the requirements of design regulations. Numerical results indicate that not only the longitudinal curvature but also the transverse curvature have a significant effect on the optimized designs of steel shell footbridge. While the mean compliance increased with the transverse curvature radius, it first decreased and then increased with the longitudinal curvature radius.

The Study on the Curvature Changes by the Experimental Impact Characteristics of Laminated Shells

양현수 한국기계기술학회 2013 한국기계기술학회지 Vol.15 No.1

The object of this study is to investigate the penetration characteristics according to the change of stacking sequences and curvature radius in the composite laminated shell. They are staked to [02/902]S and [0/902/0]S, their interlaminar number are two and four. We manufactured the composite laminated shells with various curvature radiuses. Curvature radiuses of composite shell are 100, 150, 200mm and ∞(it's meaning flat-plate). In general, the kinetic energy before and after impact increased linearly in all specimens, and the absorbed energy of the specimen [02/902]S with a small number of the interlaminars was higher than specimen [0/902/0]S.

부상화염에서 화염 곡률반경 특성에 관한 연구

하지수(Ji Soo Ha),김태권(Tae Kwon Kim),박정(Jeong Park),김경호(Kyung Ho Kim) 한국가스학회 2010 한국가스학회지 Vol.14 No.2

삼지화염의 화염안정화 메커니즘 중 중요한 한 가지는 화염전파속도이다. 화염전파속도의 정량적인 규명을 위해 Bilger는 층류 유동이론에 근거하여 혼합분율 기울기에 비선형적으로 연관된 삼지화염 전파속도를 실험으로 제시하였다. 그러나 지금까지의 연구에서는 화염의 곡률에 따른 삼지화염 전파속도에 관하여 논의된 바가 없기에, 본 논문에서 화염의 곡률에 따른 화염전파속도의 연관성을 제시하고자 하였다. 본 논문의 결과로 층류부상화염의 부상높이가 연료의 출구속도와 노즐의 직경에 따라서 결정됨을 알 수 있었다. 그리고 정지된 부상화염의 유동속도에 비례하는 연료의 출구속도에 곡률의 크기가 비례함을 보였고, 또 층류부상화염의 부상높이가 높아질수록 곡률반경의 크기가 커짐을 알 수 있었다. 따라서 곡률효과의 중요성이 인식되어야 하며 화염안정화 메커니즘을 표현하기 위해 제안된 Bilger의 제안식이 곡률효과를 고려하여 수정되어야한다. Flame propagation velocity is the one of the main mechanism of the stabilization of triple flame. To quantify the triple flame propagation velocity, Bilger presents the triple flame propagation velocity through the experiment, depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there has not been any attempt to quantify the triple flame propagation velocity with the radius of flame curvature. In the present research, a relation of the flame propagation velocity is proposed with the radius of flame curvature for the flame stabilization mechanism. As a result, we have shown that the height of lifted flame is determined with the nozzle diameter and exit velocity of fuel and presented that the radius of flame curvature is proportion to the nozzle exit velocity of fuel and height of lifted flame. Therefore, the importance of the radius of flame curvature has to be recognized. To discribe the flame stabilization mechanism, Bilgers formula has to be modified with flame curvature effect.

Study on stability evaluation and quench characteristics of non-stabilizing layer YBCO thin-film wire wound with the radius of curvature for application of SFCLS

Du, H.I.,Kim, M.J.,Han, B.S.,Song, S.S. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.20

The YBCO thin-film wire for superconducting fault current limiters shows promise with the following characteristics. (1) It has a high index value that enables a quick phase transition. (2) It has a high current density. (3) It experiences little change in the critical current in high magnetic fields. (4) It has varying quenching phenomena according to its stabilizing layers. Thus, it is being actively studied in many countries for application to power transmission and distribution systems. Based on current research results, this study examined the quenching occurrence trends in the YBCO thin-film wire that has been verified as a superconducting fault current limiter element and that has no stabilizing layers. This was done according to the wire's radii of curvature and in terms of the increase in its resistance, initial limited current, and quenching occurrence time. Five kinds of spiral-shaped formers were produced with the radii increasing from the minimum radius by 25%, taking into account their changing critical properties due to bending stress. The YBCO thin-film wire without stabilizing layers was wound around these formers. Then an alternating over-current was applied to the current limiting elements that were produced according to the radii of curvature. The resulting trends in resistance enhancement were examined to evaluate the stability of the produced current limiting elements. Finally, the produced current limiting elements' initial limited current and quenching occurrence time were observed at 90K, 180K, and 250K to evaluate the performance of the current limiting elements.