• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.685-694
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• 2010

As a eco-friendly material, Hwangtoh (red clay) has been studied for complete or partial replacement of portland cement. Most of existing studies focused on the material properties of the Hwangtoh concrete including the compressive strength, drying shringkage, and creep. In the present study, the shear strength of the beams made with the Hwangtoh concrete was tested. Further, bond strength of tension re-bars embedded in the Hwangtoh concrete was tested. One of the concrete tested consisted of activated Hwangtoh replacing 20% of the cement. The other consisted 100% activated. Hwangtoh replacing all the cement. The beam specimens were tested under two point static loading. The test result showed that the shear strength of activated Hwangtoh concrete beams replacing 20% and 100% of cement was equivalent to that of the ordinary portland cement concrete beam. However, the bond strength of activated Hwangtoh concrete replacing 100% of the cement was less than that of the ordinary portland cement concrete.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1081-1087
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• 2015

Recently, the researches of aerial drones are actively executed in various areas, the researches of surface drones and underwater drones are also executed in marine areas. In case of surface drones, they essentially utilize acoustic information by the sonar and consequently have the local information in the obstacle avoidance as the sonar has the limitations due to the beam width and detection range. In order to overcome this, more global method that utilizes optical images by the camera is required. Related to this, the aerial drone with the camera is desirable as the obstacle detection of the surface drone with the camera is impossible in case of the existence of clutters. However, the dynamic-floating aerial drone is not desirable for the long-term operation as its power consumption is high. To solve this problem, a collaborative obstacle avoidance method based on the acoustic information by the sonar of the surface drone and the optical image by the camera of the static-floating aerial drone is proposed. To verify the performance of the proposed method, the collaborative obstacle avoidances of a MSD(Micro Surface Drone) with an OAS(Obstacle Avoidance Sonar) and a BMAD(Balloon-based Micro Aerial Drone) with a camera are executed. The test results show the possibility of real applications and the need for additional studies.

• Smart Structures and Systems
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• v.18 no.5
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• pp.983-1004
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• 2016

Nowadays, there are two classes of methods for damage detection in structures consisting of static and dynamic. The dynamic methods are based on studying the changes in structure's dynamic characteristics. The theoretical basis of this method is that damage causes changes in dynamic characteristics of structures. The dynamic methods are divided into two categories: signal based and modal based. The modal based methods utilize the modal properties consisting of natural frequencies, modal damping and mode shapes. As the modal properties are sensitive to changes in the structure, these can be used for detecting the damages. In this study, using dynamic method and modal based approach (natural frequencies and mode shapes), the objective function is formulated. Then, detection of damages of truss structures is addressed by using Simplified Dolphin Echolocation algorithm and solving inverse optimization problem. Many scenarios are used to simulate the damages. To demonstrate the ability of the algorithm, different truss structures with several multiple elements scenarios are tested using a few runs. The influence of the two different levels of noise in the modal data for these scenarios is also considered. The last example of this article is investigated using a different mutation. This mutation obtains the exact answer with fewer loops and population by limited computational effort.

• Steel and Composite Structures
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• v.34 no.6
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• pp.891-907
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• 2020

Many studies reveal that during destructive earthquakes, most of the structures enter the inelastic phase. The amount of hysteretic energy in a structure is considered as an important criterion in structure design and an important indicator for the degree of its damage or vulnerability. The hysteretic energy value wasted after the structure yields is the most important component of the energy equation that affects the structures system damage thereof. Controlling this value of energy leads to controlling the structure behavior. Here, for the first time, the hysteretic behavior and energy dissipation capacity are assessed at presence of elliptical braced resisting frames (ELBRFs), through an experimental study and numerical analysis of FEM. The ELBRFs are of lateral load systems, when located in the middle bay of the frame and connected properly to the beams and columns, in addition to improving the structural behavior, do not have the problem of architectural space in the bracing systems. The energy dissipation capacity is assessed in four frames of small single-story single-bay ELBRFs at ½ scale with different accessories, and compared with SMRF and X-bracing systems. The frames are analyzed through a nonlinear FEM and a quasi-static cyclic loading. The performance features here consist of hysteresis behavior, plasticity factor, energy dissipation, resistance and stiffness variation, shear strength and Von-Mises stress distribution. The test results indicate that the good behavior of the elliptical bracing resisting frame improves strength, stiffness, ductility and dissipated energy capacity in a significant manner.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.11-20
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• 2013

Recently, as SNS services have been increased, studies on recommendation schemes have been actively done. Recommendation scheme provides various favorable or needed services with users on real time. Group recommendation provides users with suitable groups based on their preference. In this paper, we propose a new group recommendation scheme considering user profiles and collaborative filtering in social networks. The proposed scheme can solve the problems of the static profile based group recommendation scheme because it collects the recent group activities and updates user profiles. It also recommends the more various groups by reflecting the similar tendencies of other users within a group through collaborative filtering. Our experimental results show that the proposed scheme recommends various groups that significantly considers the user's changing preferences compared to the existing scheme.

• Korean Journal of Human Ecology
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• v.24 no.6
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• pp.769-781
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• 2015

The purpose of this study was to examine the effects of self control and social support on the mobile phone dependence in elementary school students. The subjects were 392 children(187 boys, 205 girls) in 5, 6th grade from two elementary schools in Gyeonggi-do. The mobile phone dependence was assessed by the Mobile Phone Dependence Scale(Ko Seong-Ja, 2012), self control was measured by the Self-control Scale(Nam hyeon-mi, 1999) and social support was assessed by the Social Support Scale(Han mi hyun, 1996). Data were analyzed using descriptive statistics, t-test, Pearson correlations and hierarchical regressions. The major results of this study were as follows: First, there was no significant difference in mobile phone dependence by sex of the children. Second, children's mobile phone dependence were correlated with self control and social support. Finally, children's self control, family support and peer support significantly explained the mobile phone dependence. But peer support appeared to have negative corelation on mobile phone dependence, but appeared to have static effect in regression result by suppressor variables. So it needs to explore statistical function of suppressor variables in follow-up studies. Also research of this study indicate that self control enhancement program should be developed and parents should communicate more frankly and affectively with their children in order to prevent children's mobile phone dependence.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.6
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• pp.74-83
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• 2008

As urban residents' standard of living has recently risen, efforts to improve urban landscapes have increased. It is very important to manage streetscapes to improve the urban landscape because they are one of the essential elements in city construction and urban landscaping. This study focuses on the indicators that manage streetscapes more accurately and realistically. To achieve this purpose, this study used dynamic simulations considering shape and layout of buildings, the primary factors in streetscapes. This study can be summarized as follows: 1. Two indicators to manage streetscape were investigated in previous studies: one to increase visual openness and the other to reduce visual overstimulation. These indicators had high correlation with scenic beauty. Therefore, increasing openness and reducing overstimulation are essential to improve streetscapes. 2. Two household tower type buildings should be arranged along roadsides to increase openness and scenic beauty. However, low tower buildings with two household are not suitable along roadsides because they create monotony and intervals are needed between buildings. 3. To increase openness, the angled arrangement of buildings is suggested $75^{\circ}{\sim}90^{\circ}(105^{\circ}{\sim}135^{\circ})$ for low buildings, $30^{\circ}{\sim}45^{\circ}(135^{\circ}{\sim}150^{\circ})$ for mid-sized buildings, and $75^{\circ}{\sim}90^{\circ}(105^{\circ}{\sim}135^{\circ})$ for high buildings. 4. To reduce overstimulation, the height and setback control regulations should be at an angle of less than $45^{\circ}$. This study suggests more accurate management guidelines by organizing the indicators that could effectively manage streetscapes and by overcoming limitations of reality shown in a static simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.338-344
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• 2020

Intolerance of Uncertainty is associated with numerous psychopathologies, including generalized anxiety disorders. However, several studies differ in the factor structures applicable for the Intolerance of Uncertainty Scale (IUS), and there exists a debate regarding the factorial and construct validity. Thus, in the current study, the IUS was newly translated to explore and verify the structures and factors relative to the cultural background of Korea. The study involved an exploratory factor analysis of randomly extracted data from 260 of 533 adults selected. Results determined that a prospective factor of 3 items and inhibitory factor of 5 items was appropriate. In addition, a confirmatory factor analysis and correlation analysis of the remaining 273 data revealed that a structural model comprising of the 8-items two factors model was well suited (x²=37.699, TLI=0.951, CFI=0.969, RMSEA=0.063, SRMR=0.039), and showed significant static correlation with worry, depression, and state-trait anxiety.

• Journal of Science of Art and Design
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• v.8
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• pp.267-296
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• 2005

Typography, as the median for communication, has expanded its roles according the attributes of the media where it Is used, and the change of media follwing the change of times is presenting new directions to the field of typography. The attempts of 20C experimental typography prioritize visual formativeness, free typography and language started to appear on printed matters and different kinds of prints put pep in magazines. Thus, experiments in the aspects of effective delivery of inpormation that letters have and aesthetic side of shapes of letter are continuing. Today with the appearance of multimedia, development of visual colture and rapid development of digital technology, the range of experimental typography has expanded even wider and therefore, different kinds of expressions became possible. As seen above, unlike the existing static printed media that carries linguistic information only, letters in the multimedia environment is shown in the movie titles, TV or web not only as a basic visual media such as type and image, but as a dynamic and complex factor that contains additional information of motion and sound factor. This study will attempt to find the historic context of focus of moment from the kinetic art and define the moving letters as kinetic typography. Therefore, this paper will have an understanding on kinetic typography's background, concept and characteristics following the change of communication environment in the multimedia era and tried to study the basic theories of kinetic typography and the information delivery and imagery function of letters. Also, this paper attempted to carry out a study on whether kinetic typography is delivering information smoothly from the aspect of communication through the image role as delivering information by studying major works of artists who have influenced kinetic typography. Based on this study, I would like to suggest new direction for effective delivery of information and value of use.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.4
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• pp.111-119
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• 2020

PURPOSE: In adults with hamstring tightness, stretching is considered a therapeutic exercise that improves flexibility. However, previous studies have reported efficacy of numerous methods, and are inconclusive in determining the most effective stretching techniques. This study aims to compare the outcomes of Evjenth-Hamberg stretching (E-HS), proprioceptive neuromuscular facilitation stretching (PNFS), and static stretching (SS), on muscle tone and flexibility. METHODS: A total of 30 subjects were assigned to each of the three stretching groups:; E-HS (n₁ = 10), PNFS (n₂ = 10), and SS (n₃ = 10). Muscle tone of the hamstring muscle, active knee extension (AKE), and passive knee extension (PKE) were assessed by range of motion. RESULTS: After the intervention, statistically significant differences were obtained between groups for muscle tone (p < .05). The post hoc test, showed statistically significant differences in muscle tone between the E-HS and PNFS groups (p < .05), and PNFS and SS groups (p < .05). Post hoc test after intervention, also revealed statistically significant differences in flexibility (p < .05) between the E-HS and PNFS groups (p < .05), E-HS and SS groups (p < .05), and PNFS and SS groups (p < .05). Moreover, a statistically significant difference was observed in PKE scores between the E-HS and SS groups (p < .05), and PNFS and SS groups (p < .05). CONCLUSION: This study indicates that E-HS may be the most effective stretching technique for muscle tone and flexibility, in adults with hamstring tightness.