• The Mathematical Education
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• v.62 no.3
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• pp.417-433
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• 2023

In the 2022 revised mathematics curriculum, a new content on 'Movement of a point' was added. Therefore, this study analyzed the contents of the movement of a point presented in Finnish mathematics textbooks as elements of spatial orientation. Analysis was conducted by dividing it into direction, distance, and route. As a result of the study, in Finnish textbooks, directions were expressed in various ways, such as linguistic, visual, and coded expressions. In the case of distance, activities to move as much as the distance or compare the distance were presented using the number of cells, length, steps, coordinate points, ratio, etc. In the case of routes, activities such as moving according to instructions, making routes, finding the route, and modifying the route were presented using unconditional movement and conditional movement. In particular, the movement of a point could be linked not only to various mathematical content areas such as 'number and arithmetic' and 'change and relationship', but also to digital literacy and programming education. Knowing that the movement of a point can be presented in various ways according to the direction, distance, and route, it is expected that it can be used to organize the contents of the 2022 revised mathematics textbook.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.6
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• pp.23-35
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• 2023

In this study, we developed a method to determine the flood-limited water levels of agricultural reservoirs, considering both their irrigation and flood control functions. Irrigation safety and flood safety indices were defined to be applied to various reservoirs, allowing for a comprehensive assessment of the irrigation and flood control properties. Seasonal flood-limited water level scenarios were established to represent the temporal characteristics of rainfall and agricultural water supply and the safety indices were analyzed according to these scenarios. The optimal scenarios were derived using a schematic solution based on Pareto front analysis. The method was applied to Obong, Yedang, and Myogok reservoirs, and the results showed that the characteristics of each reservoir were well represented in the safety indices. The irrigation safety of Obong reservoir was found to be significantly influenced by the late-stage flood-limited water level, while those of Yedang and Myogok reservoir were primarily affected by the early and mid-stage flood-limited water levels. The values of irrigation safety and flood safety indices for each scenario were plotted as points on the coordinate plane, and the optimal flood-limited water levels were selected from the Pareto front. The storage ratio of the optimal flood-limited water levels for the early, mid, and late stages were 65-70%, 70%, and 75% for Obong reservoir, 75%, 70-75%, and 65-70% for Yedang reservoir, and 75-80%, 70%, and 50% for Myogok reservoir. We expect that the method developed in this study will facilitate efficient reservoir operations.

• Korean Journal of Heritage: History & Science
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• v.54 no.2
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• pp.120-135
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• 2021

Changdeokgung Rear Garden is an important place to show the essence of the garden culture of the Joseon Dynasty. In the garden landscape experience, the restoration of the road completes the system of connecting the main spaces. Therefore, the restoration of the road requires accurate understanding of its creation, extinction, and maintenance. The purpose of this study was to detail the changes in the path that occurred in the Changdeokgung Palace Rear Garden from the late Joseon Dynasty to the modern and contemporary period by analyzing literature and drawing materials. For a time-series analysis, "Donggwoldo" and "Donggwoldohyeong" produced in the Joseon Dynasty, along with "Changdeokgung Plan Drawing" produced in modern and contemporary times, and aerial photographs were used. Drawings and photographs of different coordinate systems were transformed into one coordinate system in the geographic information system ArcGIS to compare changes in the movements of different periods. The results of the study are as follows. First, a total of 37 sections have been used since Japanese colonial era, of which 13 have been maintained, 14 have disappeared, and 10 have been newly established. Among the extinction sections, the road north of Neungheojeong Pavilion is considered to be an urgent place to connect the space to the garden and restore it to enjoy the scenery. In the new section, it seems necessary to establish a new alternative road or shorten the section for the connecting section between Daebodan and Okryucheon. Second, it was revealed that the biggest and most frequent changes to the road system in the garden were Japanese colonial era and renovations in the 1970s. It is worth noting the changes in the road since the 1970s, rather than Japanese colonial era, where it was difficult to manage the gardens independently. The access road to Okryucheon remained in its original shape until the 1990s, but it was renovated to its current shape due to misperception of the original shape. A project is needed to find out the cause of the change in this period and restore the damaged original shape. The biggest achievement of this study is that it revealed the changes in the garden path of Changdeokgung Palace in modern and contemporary times. The biggest achievement of this study is that it revealed the changes in the road of Changdeokgung Palace Rear Gardens in modern and contemporary times. However, there is a limitation that it has not been able to clearly present the location and shape that should be restored because it has not found data on landscaping plans or maintenance. In order to restore the road using the data revealed in this study, it seems necessary to consider realistic problems such as current space utilization, viewing system, disaster prevention and maintenance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.828-834
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• 2013

In this paper, TMC (Tracker Motion Controller) as one of the many research methods for condensing efficiency improvements can be condensed into efficient solar system configuration to improve the power generation efficiency of the castle with Concentrated solar silicon and photovoltaic systems (CPV)experiments using PV systems. Microprocessor used on the solar system, tracing the development of solar altitude and latitude of each is calculated in real time. Also accept the value from the sensor, motor control and communication with the central control system by calculating the value of the current position of the sun, there is a growing burden on the applicability. Through the way the program is appropriate for solar power systems and sensors hybrid-type algorithm was implemented in the ARM core with built-in TMC, Concentrated CPV system compared to the existing PV systems, through the implementation of the TMC in the country's power generation efficiency compared and analyzed. Sensor method using existing experimental results Concentrated solar power systems to communicate the value of GPS location tracking method hybrid solar horizons in the coordinate system of the sun's azimuth and elevation angles calculated by the program in the calculations of astronomy through experimental resultslook clear day at high solar irradiation were shown to have a large difference. Stopped after a certain period of time, the sun appears in the blind spot of the sensor, the sensor error that can occur from climate change, however, do not have a cloudy and clear day solar radiation sensor does not keep track of the position of the sun, rather than the sensor of excellence could be found. It is expected that research is constantly needed for the system with ongoing research for development of solar cell efficiency increases to reduce the production cost of power generation, high efficiency condensing type according to the change of climate with the optimal development of the ability TMC.

• Journal of the Korea Computer Graphics Society
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• v.18 no.4
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• pp.1-8
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• 2012

We present improved deformation energy to enhance the visual quality of a shape deformation technique, where we preserve the local structure of an input planar shape. The deformation energy, in general, consists of several constraints such as Laplacian coordinate constraint to preserve the quality of deformed silhouette edges, mean value coordinates and edge length constraints to preserve the quality of deformed internal shape, and user-specified position constraints to control the shape deformation. When the positions of user-specified vertices change, shape deformation techniques compute the positions of the other vertices by means of nonlinear least squares optimization to minimize the deformation energy. When a user-specified vertex changes its position rapidly, it is frequently observed that the visual quality of the deformed shape decrease rapidly, which is mainly caused by unnecessary enlargement of the Laplacian vectors and unnecessary change of the edge directions along the boundary of the shape. In this paper, we propose improved deformation energy by prohibiting the Laplacian and edge length constraints from changing unnecessarily. The proposed deformation energy incorporated with well-known optimization technique can enhance the visual quality of shape deformation along the silhouette and within the interior of the planar shape while sacrificing only a little execution time.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.2
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• pp.79-93
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• 2015

Three-dimensional structures of large ocean rings in the Gulf Stream region are investigated using the HYbrid Coordinate Ocean Model (HYCOM). Numerically simulated flow structures around four selected cyclonic and anticyclonic rings are compared with two different horizontal resolutions: $1/12^{\circ}$ and $1/48^{\circ}$. The vertical distributions of Lagrangian Coherent Structures (LCSs) are analyzed using Finite Size Lyapunov Exponent (FSLE) and Okubo-Weiss parameters (OW). Curtain-shaped FSLE ridges are found in all four rings with extensions of surface ridges throughout the water columns, indicating that horizontal stirring is dominant over vertical motions. Near the high-resolution rings, many small-scale flow structures with size O(1~10) km are observed while these features are rarely found near the low-resolution rings. These small-scale structures affect the flow pattern around the rings as flow particles move more randomly in the high-resolution models. The dispersion rates are also affected by these small-scale structures as the relative horizontal dispersion coefficients are larger for the high-resolution models. The absolute vertical dispersion rates are, however, lower for the high-resolution models, because the particles tend to move along inclined eddy orbits when the resolution is low and this increases the magnitude of absolute vertical dispersion. Since relative vertical dispersion can reduce this effect from the orbital trajectories of particles, it gives a more reasonable magnitude range than absolute dispersion, and so is recommended in estimating vertical dispersion rates.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.155-164
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• 2007

This study is to find out effective defensive type by analysis on differences among three different defence types of the body lock technique in the ground wrestling. The subjects are 5 athletes who are in 60kg weight class. To get the kinematic analysis seven ProReflex MCU-240(Motion Capture Unit), infrared rays cameras, which was produced by Qualisys, were used to get a two-dimensional coordinate. Following are the analysis result from kinematic factors such as time element, speed element and angular element. 1. During position of ground wrestling, the average necessary time until defender's hip joint touches the mat for Phase1 was $0.34{\pm}0.14sec$ at side position was the shortest space of time out of three types, and Phase2 was $0.21{\pm}0.02sec$ at front position was the shortest space of time out of three types. Moreover, side defence position was the shortest for total average necessary time with $0.78{\pm}0.05sec$. 2. The movement change for hip joint was $57.21{\pm}20.17cm$ for front, $43.35{\pm}7.13cm$ for rear, and $18.67{\pm}10.24cm$ for side at Phase1 and $42.08{\pm}17.56cm$ for side, $16.61{\pm}6.34cm$ for front, and $1.48{\pm}1.29cm$ for rear at Phase2. 3. Movement speed of hip joint at defensive type were most effective in success and fail rate at Phase 1 and its frontal average speed was fastest with $1.01{\pm}0.23m/s$ following by $0.52{\pm}0.15m/s$ for side, and $0.62{\pm}0.15m/s$ for rear. The average for total change of speed is $0.79{\pm}0.32m/s$ for front, $0.78{\pm}0.17m/s$ for side, and $0.49{\pm}0.08m/s$ for rear. 4. The joint angle gets smaller in a order by rear, front, and side for the size of hip joint angle and knee angle for different defensive type. 5. As a result of one-way ANOVA on linear velocity for hip joint in frontal defence(phase1) was significance ($\alpha$=.05), but phase 2 was not significance. Synthetically, analyzing on differences among three different defence types which were front, rear, and side of the body lock technique in the ground wrestling, front defensive type was the most effective. In future, there should be more studies regarding on defence at not a laboratory study but a field study to help out wrestler to pertinent techniques to improve the game of wrestling.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2691-2696
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• 2009

Effects of representative group II and transition metal ions on the stability of the $poly(dA){\cdot}[poly(dT)]_2$ triplex were investigated by the van’t Hoff plot constructed from a thermal melting curve. The transition, $poly(dA){\cdot}[poly(dT)]_2\;{\rightarrow}\;poly(dA){\cdot}poly(dT)\;+\;poly(dT)$, was non-spontaneous with a positive Gibb’s free energy, endothermic (${\Delta}H^{\circ}$ > 0), and had a favorable entropy change (${\Delta}S^{\circ}$ > 0), as seen from the negative slope and positive y-intercept in the van’t Hoff plot. Therefore, the transition is driven by entropy change. The $Mg^{2+}$ ion was the most effective at stabilization of the triplex, with the effect decreasing in the order of $Mg^{2+}\;>\;Ca^{2+}\;>\;Sr^{2+}\;>\;Ba^{2+}$. A similar stabilization effect was found for the duplex to single strand transition: $poly(dA){\cdot}poly(dT)\;+\;poly(dT)\;→\;poly(dA)\;+\;2poly(dT)$, with a larger positive free energy. The transition metal ions, namely $Ni_{2+},\;Cu_{2+},\;and\;Zn_{2+}$, did not exhibit any effect on triplex stabilization, while showing little effect on duplex stabilization. The different effects on triplex stabilization between group II metal ions and the transition metal ions may be attributed to their difference in binding to DNA; transition metals are known to coordinate with DNA components, including phosphate groups, while group II metal ions conceivably bind DNA via electrostatic interactions. The $Cd_{2+}$ ion was an exception, effectively stabilizing the triplex and melting temperature of the third strand dissociation was higher than that observed in the presence of $Mg_{2+}$, even though it is in the same group with $Zn_{2+}$. The detailed behavior of the $Cd_{2+}$ ion is currently under investigation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.216-227
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• 2004

A new cavitating model by using bubble size distribution based on bubbles-mass has been proposed. Both liquid and vapor phases are treated with Eulerian framework as a mixture containing minute cavitating bubbles. In addition vapor phase consists of various sizes of vapor bubbles, which are distributed to classes based on their mass. The bubble number-density for each class was solved by considering the change of the bubble-mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method, the bubble-mass is treated as an independent variable, and the other dependent variables are solved in spatial coordinates and bubble-mass coordinate. Firstly, we employed this method to calculate bubble nucleation and growth in stationary super-heated liquid nitrogen, and bubble collapse in stationary sub-cooled one. In the case of bubble growth in super-heated liquid, bubble number-density of the smallest class based on its mass is increased due to the nucleation. These new bubbles grow with time, and the bubbles shift to larger class. Therefore void fraction of each class is increased due to the growth in the whole class. On the other hand, in the case of bubble collapse in sub-cooled liquid, the existing bubbles are contracted, and then they shift to smaller class. It finally becomes extinct at the smallest one. Secondly, the present method is applied to a cavitating flow around NACA00l5 foil. Liquid nitrogen and liquid oxygen are employed as working fluids. Cavitation number, $\sigma$, is fixed at 0.15, inlet velocities are changed at 5, 10, 20 and 50m/s. Inlet temperatures are 90K in case of liquid nitrogen, and 90K and 1l0K in case of liquid oxygen. 110K of oxygen is corresponding to the 90K of nitrogen because of the same relative temperature to the critical one, $T_{r}$=$T/T_c^{+}$. Cavitating flow around the NACA0015 foils was properly analyzed by using bubble size distribution. Finally, the method is applied to a cavitating flow in an inducer of the LE-7A hydrogen turbo-pump. This inducer has 3 spiral foils. However, for simplicity, 2D calculation was carried out in an unrolled channel at 0.9R cross-section. The channel moves against the fluid at a peripheral velocity corresponding to the inducer revolutions. Total inlet pressure, $Pt_{in}$, is set at l00KPa, because cavitation is not generated at a design point, $Pt_{in}$=260KPa. The bubbles occur upstream of the foils and collapse between them. Cavitating flow in the inducer was successfully predicted by using the bubble size distribution.

• Journal of the Korean association of regional geographers
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• v.14 no.2
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• pp.93-104
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• 2008

This article will divide agricultural change process in Yanbian area into the period of japan rule, socialism and later time of the reform and open policy and so on. It will analyze the changes of Yanbian agriculture in every period influenced by external environment influence. The conclusions are as follow: first, under the influence of the japan rule, the policy about Korean Minority immigrants in japan and the original work agriculture and the group tribe construction, Yanbian fanning was controlled by the Japanese. Therefore, Yanbian's agriculture became the tool to satisfy the war and plunder the resource for Japanese. It shows the obviously peripheral characteristics. Second, in socialism time, Yanbian's agriculture was influenced by the rural communalization. The fanning completely belongs to the country, the agricultural production is influenced by the idea of "grain as the key link" which it only pays attention to take the cultivation industry and the production of grain in the interior of cultivation industry. Therefore, it has not been able fully to use the rich natural resource. Third, after reform and open policy, the countrysides were implemented family contract responsibility system, the farmer can rent the land for a long time, and the enthusiasm of agricultural production was improved. Moreover, due to the social market economy-system, the farmer carried on the agricultural production activities according to the market's demands and various departments of the agriculture obtained the coordinate development.