• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.189-194
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• 2019

This thesis aimed to apply the 3D-printing technology rapidly introduced to the overall industry to jewelry design. In the results of examining preceding researches, out of 3D-printing methods, the FMD method was used the most in design area. However, for jewelry design, the 3D-printing is used for casting process out of production processes, so that the printing method is not FMD, but DLP. Thus, the researcher examined the material functions and applicability of jewelry design through research works, by applying the 3D-printing in DLP method to jewelry design. In the results, brooches were completed by applying the 3D-printing to the jewelry design with no casting process, and then utilizing enamel and pure silver together. Producing light and solid completed products in various colors, they were verified as applicable materials. Also, as the size and form of curved design mainly used for non-geometric jewelry design could be accurately predicted through Rhino CAD, diverse possibilities of advancement to be easily used for the development of formative form of jewelry design in the future were revealed.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.10-18
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• 2002

Rock joint system makes a heavy effect on the behavior of rock structures. The definition of a 3D rock joint system is very important in 2D or 3D numerical analysis for the prediction of the behavior of a discontinuous rock mass. To enhance the reality of a 3D definition of rock joint system, it is essential to estimate the unbiased statistics of basic geometric attributes of rock joints. In this study, we have proposed the statistical analysis and derived the related equations for an estimation of statistics of joint size and intensity. Geometry of rock joints in 3 dimensional space can be defined by the aggregate of location, size, orientation and intensity. The dimensional limit of survey method and its data makes 3D geometric attributes probabilistic. In the estimation of statistics of joint size, we have discussed the technique to correct the bias from a dimensional limit and derived the equation of 3D joint intensity by stereological approaches.

• Journal of Educational Research in Mathematics
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• v.20 no.3
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• pp.275-292
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• 2010

In this study, we discussed the way to teach algebra earlier through investigating to research trends of Early Algebra and researching about nature of subject involving algebra. There is a strong view that arithmetic and algebra have analogous forms and that algebra is on extension to arithmetic. Nevertheless, it is also possible to present a perspective that the fundamental goal and role of symbols and letters are difference between arithmetic and algebra. And, we could recognize that geometry was starting point of algebra trough historical perspectives. To consider these, we extracted some of possible directions to approaches to teach algebra earlier. To access to teaching algebra earlier, following ways are possible. (1) To consider informal strategy of young children. (2) Arithmetic reasoning considered of the algebraic relation. (3) Starting to algebraic reasoning in the context of geometrical problem situation. (4) To present young students to tool of letters and formular.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.801-809
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• 1985

다음 세대의 우주 비행선(spacecraft) 및 우주 구조물 등은 매우 정밀한 수행 능력은 물론 발사 경비의 절감을 위해 자체 무게를 최대한 줄일 수 있는 설계 방안을 요구하고 있다. 이같은 중 요한 요구 조건들을 만족시킬 수 있는 진동 제어의 한 방법으로써 재료 고유진동감쇠(material damping)의 효과적인 응용이 매우 중요시 되고 있다. 따라서, 본 연구에서는 열기류(Thermal currents)에 의해 발생하는 열탄성 진동감쇠(thermoelastic damping)를 연관 열탄성학(coupled thermoelasticity)에 근거하여 해석적으로 추정하고 진동감쇠율에 구조적, 기하학적 형태가 미치는 영향에 관해 고찰하였다. 단일 구조물의 형태, 경계조건 및 진동모우드 등이 진동감쇠에 미치는 영향을 새로운 계수로서 공식화 하였으며 아울러 최대 진동 감쇠율을 얻을 수 있는 최적조건을 고찰하였다.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.55-63
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• 2007

This research deals with the relations between intersection types and traffic accidents in the case of Korean expressways. The purpose of this research is to test the hypotheses that traffic accidents depend on intersection types and geometric design elements. The main research results are as follows. First, the accident comparisons that are drawn from junctions with interchanges, and trumpet interchanges with other types of interchanges respectively displays no significant meaning. However, the differences among four types of trumpet interchanges are found to be meaningful. In other words, the BO type trumpet interchanges seem to have far more traffic accidents than other types of trumpet interchanges. Second, hypothesis tests show that approximately 90 degree and one lane connection roads have lower accident rates. Based on this research, the following directions can be suggested for the safer types of intersections and geometric design elements in freeway construction. From a road safety point of view, it is advisable not to introduce BO type interchanges. It is also desirable that the intersection angle should be approximately 90 degrees. Furthermore, it would be wise to design one lane roads if the connection road has low traffic volumes.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.4
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• pp.541-561
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• 2016

In this paper we discussed about the contents which were related with geometric construction in elementary school. We examined how the compass has been used in the curriculum and textbooks. Thus we found several features. And we inspected the ideas and sequences about geometric construction in Waldorf mathematics education. Finally, we suggested how to change the contents to make the relationships between elementary school and middle school better.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.24-31
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• 2006

In this paper, mechanical behavior of unidirectional composites with flexible matrix was predicted by geometrical non-linear finite element analysis. Two typical idealized unit cells of square and hexagonal fiber arrays were modeled and these were subjected to different loadings. The stress-strain behavior of composites was predicted from which the effective properties were calculated. The hyperelasticity of polyurethane matrix was considered using Mooney-Rivlin model. In result, the stress-strain behavior of flexible composites shows non-linearity, especially it is remarkable under transverse normal and shear loading conditions. In this cases, there are great difference between square and hexagonal fiber array models.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.3 s.21
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• pp.79-87
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• 2002

This paper proposes an approach of automatically identifying the center of fiducial marks using radiometric and geometric characteristics of those marks existing on aerial photographs. Candidate region surrounding a mark, based on radiometric strategy, is determined by producing a bi-level image and by applying morphological operations. Based on geometric strategy, the central location of a mark is determined by applying ${\bigtriangledown}^G$ filtering and symmetry-enhancement filtering, and by finding peak location of symmetry. Evaluation with respect to 66 cases of sub-images containing a fiducial mark showed that the central location of the mark is determined up to around one pixel difference whit it is compared to a manual inspection.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.47-56
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• 2003

There are no specific criteria deciding what type of crosswalk installs although 4 typed crosswalks at signalized intersections classify according to number of stop line, spacing from the border of intersections and existence of traffic islands or not. Accidents involving pedestrians at signalized intersections are classified by type of crosswalks by traffic volume, pedestrian volume at crosswalk, intersection geometry and phase in view of pedestrians' safety at 50 intersections in Gwangju. The Multiple regression models are applied to express the pedestrian accident rate. In addition, process deciding what type of crosswalk installs which includes accident rate involved pedestrian is changed into number of accident is represented to reduce number of accidents. This paper presents what type of crosswalk installs in order to reduce pedestrian involved accidents at new or existing crosswalk.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.95-105
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• 2004

The fundamental diagram is a important element in a variety of transportation studies. While various shapes of the fundamental diagram have been proposed and numerous debates on the best-fit fundamental diagram have been made, the reason why the fundamental diagram has many different shapes has not been well explained. This study introduces time sap as a key parameter to understand drivers' behavioral differences at different locations and traffic conditions, then relate to the shape of the fundamental diagram. From the freeway event detector data, it is shown that time gap follows a certain probabilistic distribution and its mean value varies along locations. It also turns out that drivers take different time gaps for different travel speeds. Three different types of time gap-speed diagrams are identified and matched to Greenberg, reversed-lambda, and inverted-V types of fundamental diagrams, respectively. This study explains the characteristics of fundamental diagrams using time gap as a microscopic variable and describes drivers' behavioral characteristics according to traffic and geometric conditions.