• Journal of Korean Society of Steel Construction
• /
• v.15 no.5 s.66
• /
• pp.541-549
• /
• 2003

Split-tee connection with High Strength Bolts is normally used in low and middle rise buildings in Europe because the structural efficiency and installation work of connections are excellent. However, the domestic situation is different from that in Europe. The analysis and the design for the T-split connection are complicated, because the structural behavior often T-split connection with High Strength Bolt is governed by so many parameters, i.e., prying action, bolt's tension, shear failure and plastic failure of flange plates. Many researches regarding the structural behavior of the split-tee connection have been undertaken in other parts of the world, such as the, Americas, Japan and Europe, but in the domestic context, this is a pioneering study. Therefore, the purpose of this paper is to supply basic data for the design of T-split connection, and to verify the structural characteristics that define reactions to prying action, based on an experimental study.

• Journal of Korea Water Resources Association
• /
• v.57 no.10
• /
• pp.725-739
• /
• 2024

In Korea, the national PMP map is used to calculate the Probable Maximum Precipitation (PMP) but the intercept adjustments are necessary to obtain uniform PMP envelopment results. The Box-Cox and cubic Spline methods to get the PMP envelopment modeling were proposed by the past studies.. However there has been no significant progress in the study of PMP envelopment modeling since then. This study, which focused on the last step of PMP estimation process in Korea, used the Monotone Cubic Spline (MCS) and compared with existing methods. As a result, the intercept adjustments involving the engineer's subjectivity were necessary to obtain smooth envelopment curves in case of using the existing method such as the cubic spline. However, a smooth envelopment curves were obtained without intercept adjustment in case of using MCS method. Therefore, using the MCS method for dam-related new projects can get smooth and consistent envelopment results without intercept adjustment for PMP calculation in Korea.

• School Mathematics
• /
• v.7 no.4
• /
• pp.391-402
• /
• 2005

The purpose of this study is to resolve misunderstanding for centroid of a triangle and to clarify several logical problems in finding the centroid of a Polygon. The conclusions are the followings. For a triangle, the misunderstanding that the centroid of a figure is the intersection of two lines that divide the area of the figure into two equal part is more easily accepted caused by the misinterpretation of a median. Concerning the equilibrium of a triangle, the median of it has the meaning that it makes the torques of both regions it divides to be equal, not the areas. The errors in students' strategies aiming for finding the centroid of a polygon fundamentally lie in the lack of their understanding of the mathematical investigation of physical phenomena. To investigate physical phenomena mathematically, we should abstract some mathematical principals from the phenomena which can provide the appropriate explanations for then. This abstraction is crucial because the development of mathematical theories for physical phenomena begins with those principals. However, the students weren't conscious of this process. Generally, we use the law of lever, the reciprocal proportionality of mass and distance, to explain the equilibrium of an object. But some self-evident principles in symmetry may also be logically sufficient to fix the centroid of a polygon. One of the studies by Archimedes, the famous ancient Greek mathematician, gives a solution to this rather awkward situation. He had developed the general theory of a centroid from a few axioms which concerns symmetry. But it should be noticed that these axioms are achieved from the abstraction of physical phenomena as well.

• The Journal of Korean Philosophical History
• /
• no.29
• /
• pp.203-230
• /
• 2010

This article is aimed for to state the rationality of Mojia and reveal the scientific meaning in the theories related to the motion of objects in Mojing: the basic approach to the principle of gravitation in building castle, and comprehension and application of the principle in the lever devised for improving productivity as well as in an inclined plane. It is denied in this article that the technical advance and the positive influence on the people is achieved by Mojias only because they were occupied in the filed of craft. Mojia was one of the schools of Qin in the early stage who realized how important science wass for the better society focused on humanity. Furthermore, they were the frontiers who pursued the proper society through science. Therefore, the scientific theories claimed by Mojia is not emphasized only on the deducting regularity of nature. Instead, it could be theorized only by guaranteeing the welfare for common people and having close relation to it. The Chinese philosophy in the early Twentieth century had vigorous interest in the Mojia's opinions in science and set about conducting study in this part. Based on the study, it was revealed that the Mojia's opinion toward motion is superior to that of the West. Furthermore, it was proved to reflect the main idea in Mojia: the love for common people. Particularly, the theories from Mojia can be so applicable to today's life that some scholars regret the lack of interest in Mojia for the time and even scold themselves for the retarded progress in science of China.

• Publications of The Korean Astronomical Society
• /
• v.34 no.3
• /
• pp.31-40
• /
• 2019

We study the internal structure under the artificial mountain of Heumkyeonggak-nu, a Korean water-powered clock in the early Joseon dynasty. All the puppets on the artificial mountain are driven by the rotational force generated by the water wheel at their designated time. We design a model that work with three parts of the artificial mountain. At the upper part of the artificial mountain to the east, west, north and south, there are four puppets called the Four Mystical Animal Divinity and four ladies called the Jade Lady respectively. The former rotates a quarter every double hour and the latter rings the bell every hour. In the middle part of this mountain is the timekeeping platform with four puppets; the Timekeeping Official (Hour Jack), the Bell-, Drum-, and Gong-Warriors. The Hour Jack controls time with three warriors each hitting his own bell, drum, and gong, respectively. In the plain there are 12 Jade Lady puppets (the lower ladies) combined with 12 Oriental Animal Deity puppets. In his own time a lady doll pops out of the hole and her animal doll gets up. Two hours later, the animal deity lies down and his lady hides in the artificial plain. These puppets are regularly moved by the signal such as iron balls, bumps, levers, and so on. We can use balls and bumps to explain the concept of the Jujeon system. Iron balls were used to manipulate puppets of the timekeeping mechanism in Borugak-nu, another Korean water-powered clock in Joseon dynasty, which was developed earlier than Heumgyeonggak-nu. According to the North Korea's previous study (Choi, 1974), it is obvious that bumps were used in the internal structure of Heumgyeonggak-nu. In 1669, The armillary clock made by Song, I-young was also utilized bumps. Finally we presented mock-ups of three timekeeping systems.