• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.59-66
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• 2018

The utilized coefficient of friction (UCOF) as a ratio of the shear force to the normal force on the ground during walking is used to identify the point at which slip is likely to occur. Shoe walking will change the utilized coefficient of friction by shoe design such as sole thickness and hardness, heel shape, and outsole pattern. In this study, subjects are 21 adults (10 female, 11 male, age: $25.2{\pm}2.3yrs$, height: $165.6{\pm}7.2cm$), analysis variables were walking speed, GRF, when the UCOF is maximal, and Tangent of CoP-CoM angle, and correlation analysis with the utilized friction coefficient (UCOF). As a result, First, for the shod walking the time point which UCOF is maximum about heel strike was faster and the magnitude was larger than for barefoot walking. Second, the correlation between the tangent of CoP-CoM and UCOF of right foot was higher at the left heel striking point (UCOF2_h) which occurred in the post propulsion phase than at the right heel striking point (UCOF1_h). This suggests that the right foot UCOF is related to the braking phase of left foot( which is the propulsion phase of right foot) rather than the braking phase of right foot.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.225-233
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• 2019

In the summer season, natural ventilation is commonly used to reduce the inside air temperature of greenhouse when it rises above the optimal level. The greenhouse shape, vent design, and position play a critical role in the effectiveness of natural ventilation. In this study, computational fluid dynamics (CFD) was employed to investigate the effect of different roof vent designs along with side vents on the buoyancy-driven natural ventilation. The boussinesq hypothesis was used to simulate the buoyancy effect to the whole computational domain. RNG K-epsilon turbulence model was utilized, and a discrete originates (DO) radiation model was used with solar ray tracing to simulate the effect of solar radiation. The CFD model was validated using the experimentally obtained greenhouse internal temperature, and the experimental and computed results agreed well. Furthermore, this model was adopted to compare the internal greenhouse air temperature and ventilation rate for seven different roof vent designs. The results revealed that the inside-to-outside air temperature differences of the greenhouse varied from 3.2 to $9.6^{\circ}C$ depending on the different studied roof vent types. Moreover, the ventilation rate was within the range from 0.33 to $0.49min^{-1}$. Our findings show that the conical type roof ventilation has minimum inside-to-outside air temperature difference of $3.2^{\circ}C$ and a maximum ventilation rate of $0.49min^{-1}$.

• Journal of Korea Technology Innovation Society
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• v.22 no.3
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• pp.362-381
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• 2019

The purpose of this study is to examine how two factors among various affecting factors of technological innovation, i.e. sectoral system of innovation and R&D support service, were actually applied in the case of NUC Electronics. This company has achieved high level of innovation performance through change of injection port and improvement of extracting rate. This was possible because each component of sectoral system of innovation system was matched with the innovation activity. The improvement of the performance in NUC Electronics was attributable to its own innovation efforts and R&D support service of government research institute. In the process of technological innovation, the company could receive high-level services in areas such as product design and virtual experiments that companies can not solve themselves. It can be said that the role of government and public institutions to support the shortage of SMEs was important. In terms of each component of sectoral system of innovation, we found that there were many opportunities of new technology; sustainability was low; imitation was easy; appropriability was low but it has dualily; accumulation of technology was relatively high, availability of external knowledge was high. At the same time, both of the company and the network played an important role, and market conditions were very favorable. In terms of R&D support services, it is a direct effect that a great deal of time and cost savings have been achieved through virtual experiments on the material and shape of the screw. As an indirect effect, the core competence of the company has been greatly strengthened by utilizing the momentum of technology development through external support, hence the company could establish the structure of virtuous circle of innovation.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.23-33
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• 2019

A sub-munition which has low aspect ratio does not have flight stability and control of drag force under free-fall condition. In order to satisfy those problems, fin, which is called grid-fin, is designed instead of conventional flight fins and adapted to the sub-munition. The base model of the sub-munition is firstly set and numerical simulation of the model is conducted under transonic condition that is free-fall range of the sub-munition. Wind test is secondly performed to verify the simulation result. The result shows that grid fin adapted sub-munition has high drag force, but the flight stability is still needed. In order to enhance the flight stability, two additional grid-fins are designed which modify web-thickness and numerical simulations of modified models are conducted. As the results, the thinnest web-thickness grid-fin has the highest flight stability and still maintains high drag coefficient. Based on these results, design of grid-fin adapted sub-munition is completed, the path trajectory of the sub-munition can be predicted with acquired aerodynamic datum and it is expected that grid fin can be used to various shape of the flight vehicle and bomb.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.413-425
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• 2019

We see many images every day, some of these images are stored in memory, and the majority are immersed in the unconscious world. Visual elements are seen by personal attention or by visual or biological attention factors. Specific and clear discovery of this visual attention has not yet been made. However, there is an interesting discussion of this visual attention in the fields of interior, design, visual perception, advertising, and psychology. Advertising photographers are expected to produce what their work will have on viewers and consumers. However, the adjustment of subject, exposure, color, or post-production, which could have a visual effect on the consumer, was determined only by the photographer's senses rather than the experimental verification. The advertisement photographs provide a specific image related to the object to be advertised and deliver a certain message. Therefore, it is necessary to understand the effect of the image in a certain visual way. According to previous studies, there are two major factors that affect the visual impression of the viewer. One is the factor depending on the type and content of the subject and the other is the factor about the density and color of the subject. The purpose of this study is to investigate the meaningful changes in the visual perception depending on the shape, content, color and tone of the subject, which can be called the main subject, And to analyze the effects of I will study some implications of visual elements through various analyzes.

• Design & Manufacturing
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• v.13 no.2
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• pp.30-36
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• 2019

Traditional cell culture(2-dimensional) is the method that provide a nutrient and environment on a flat surface to cultivate cells into a single layer. Since the cell characteristics of 2D culture method is different from the characteristics of the cells cultured in the body, attempts to cultivate the cells in an environment similar to the body environment are actively proceeding in the industry, academy, and research institutes. In this study, we will develop a technology to fabricate micro-structures capable of culturing cells on surfaces with various curvatures, surface shapes, and characteristics. In order to fabricate the hemispheric plastic structure(thickness $50{\mu}m$), plastic preform mold (hereinafter as "preform mold") corresponding to the hemisphere was first prepared by injection molding in order to fabricate a two - layer structure to be combined with a flat plastic film. Then, thermoplastic polymer dissolved in an organic solvent was solidified on a preform mold. As a preliminary study, we proposed injection molding conditions that can minimize X/Y/Z axis deflection value. The effects of the following conditions on the preform mold were analyzed through injection molding CAE, [(1) coolant inlet temperature, (2) injection time, (3) packing pressure, (4) volume-pressure (V/P). As a result, the injection molding process conditions (cooling water inlet temperature, injection time, holding pressure condition (V / P conversion point and holding pressure size)) which can minimize the deformation amount of the preform mold were derived through CAE without applying the experimental design method. Also, the derived injection molding process conditions were applied during actual injection molding and the degree of deformation of the formed preform mold was compared with the analysis results. It is expected that plastic film having various shapes in addition to hemispherical shape using the preform mold produced through this study will be useful for the molding preform molding technology and cast molding technology.

• Korean Journal of Heritage: History & Science
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• v.42 no.3
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• pp.176-191
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• 2009

This report is a result of investigating the materials and techniques of the lacquer ware excavated from Hwangnamdaechong Tomb known as an old tomb in the Gyeongju maximum district. First, the fragment of lacquer ware was classified by the shape of it. Next, the thin section of lacquer film (all sides about 2mm) was made based on the result. Then they were observed under the microscope, and classified the kind of the foundation mixture and the applied structure. It is a result as follows. 1 The bone dust was mixed by the foundation of the made of cloth-body lacquer ware such as eared lacquer cup, lacquer bowl, and the lacquer rectangular containers excavated from the south tomb. 2 Eared lacquer cup and lacquer bowl, and rectangular box excavated from south and north tomb had the possibility they were the set of articles partially of tableware and the cosmetic box. 3 There is a difference in the quality of burial lacquer ware between in south tomb and north tomb. A lot of highlevel lacquer ware such as eared lacquer cup, lacquer bowl and the rectangular lacquer containers were discovered from the south tomb. 4 Many of containers where animal and bird had been drawn on the black lacquered ground excavated from north tomb were wooden bath.

• Korean Journal of Heritage: History & Science
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• v.43 no.1
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• pp.212-235
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• 2010

The purpose of this study is to examine the characteristics of the location and the spatial composition of Uireung that is located in Seokgwan-dong, Seongbuk-gu, Seoul, in order to understand the landscape architectural characteristics. The results are as follows. First, Uireung is 6.4km from Changdeokgung Palace and 5.5km from Heunginjimun Gate. It did not violate the distance standard (40km) for the royal tombs according to Joseon Dynasty Neung-won Myo-je. Second, Uireung is in harmony with the nature and shows the authoritative characteristics of the royal authority through the spatial composition and rank(Entrance Area, Ceremonial Area, Burial Area). Third, there are burial mound, stone sheep, stone tiger, stone table, stone watch pillars in the upper platform, and stone civil official, stone horse, stone lantern in the middle platform, and stone military official, stone horse in the lower platform, and T-shape shrine, worship road in the ceremonial area. There is no pond and a tomb keeper residence, but the position, size, and form can be approximated through historical research materials. There are a colony of pine trees around the burial mound and 64 species of trees such as pine tree, zelcova tree, and fir tree below the burial mound.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.918-925
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• 2017

Multiple reflections on exterior equipment with complex shape on naval ships cause unexpectedly high Radar Cross Section (RCS) distributions, and the directions of reradiated electromagnetic waves are hard to predict. Therefore, the optimum arrangement of exterior equipments should be considered according to the Radar Absorbing Structure (RAS) method. In this paper, the optimum arrangement for exterior equipments was determined to reduce multiple reflections and RCS even with complex shapes. The sequential descending arrangement method was used to establish an optimum arrangement algorithm. An LCS-2 type model was selected for optimum exterior equipment arrangements. In order to reduce computational cost, RCS distributions and multiple reflection path analysis of exterior equipments was carried out to select exterior equipments for optimum arrangement, and an optimum arrangement was determined to find positions with minimum RCS values. Also, the RCS reduction effect was analyzed using detectable radar range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.481-487
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• 2019

Additive manufacturing is a state-of-the-art manufacturing process technology in which three-dimensional structures are fabricated by laminating two-dimensional sections of a structure using various materials such as plastic, ceramics, and metals. The additive manufacturing technology has the advantage of high design freedom, while the surface property (roughness) of the finished product varies depending on the process conditions, which necessitates performing a post-process after the products are manufactured. In this study, the surface roughness of a structure made of polyamide 12, which was manufactured by SLS (Selective Laser Sintering) and MJF (Multi Jet Fusion) process was compared. The processing condition was classified by the building orientation of structure as 0, 45, and 90 degrees, which is the angle between the analytical surface and the horizontal plane of the fabrication platform. Structures with a hole of various diameters ranging from 1mm to 10mm were manufactured and the hole characteristics (ratio of hole depth to diameter) and results of the specimens were compared. As a result of the surface characteristics analysis, the surface roughness value of the specimens manufactured with a building orientation of $45^{\circ}$ was the highest in both technologies. In the case of the through-hole structure fabrication, the shape was maintained with 5mm and 10mm diameter holes regardless of the building orientation, although the hole forming was difficult for the smaller holes.