• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.4
• /
• pp.50-58
• /
• 2014

Due to the cost burden of new construction, the necessity of repair and retrofitting of aged structures is sharply increasing as the domain of repair and retrofitting construction is expanding. Because of the necessity, new technologies for repair and retrofitting are continuously studied in Korea and foreign countries. Steel adhesive method, fiber reinforced plastic (FRP) surface adhesive method, and external prestressing method are used to perform the repair and retrofitting works in Korea. In order to consider a repair method using steel mesh reinforced cement mortar (SMCM), 3-point flexural member test was conducted considering repair area and layer number of SMCM. Five types of specimens including ordinary reinforced concrete (RC) specimen with dimensions of $1400{\times}500{\times}200$ (mm) were cast for testing the deflection measurement, a LVDT was installed at the top center of the specimens. Also, a steel strain gauge and a concrete strain gauge were placed at the center of the specimens. A steel strain gauge was also installed on the shear reinforcement. The 3 point flexural member test results showed that the maximum load of SMCM reinforced specimen was higher than that of basic RC specimen in all of the load-displacement curves. Also, the results showed that, when the whole lower part of the basic RC specimen was reinforced, the maximum load and strain were 1.18 and 1.37 times higher than that of the basic RC specimen, respectively. Each specimen showed a slightly different failure behavior where the difference of the results was caused by the difference in the adhesive level between SMCM and RC. Particularly, in SM-B1 specimen, SMCM spalled off during the experiment. This failure behavior showed that the adhesive performance for RC must be improved in order to utilize SMCM as repair and retrofitting material.

• 한국HCI학회:학술대회논문집
• /
• 2008.02b
• /
• pp.152-157
• /
• 2008

The customer satisfaction of WAP service greatly relies on the usability of the service due to the limited display size of a mobile phone and limitation in realizing UI (User Interface) for function keys, browser, and OS (operating system) Currently, a number of contents providers develop and deliver varying services, and thus, it is critical to control quality level of UI in consistent standards and manner. This study suggests usability index evaluation system to achieve consistent UI quality control of various WAP services. The system adopts both top-down and bottom-up approaches. The former concerns deriving UI design components and evaluation checklists for the WAP, based on the usability attributes and UI principles. The latter concerns deriving usability-related evaluation checklists from the established UI design features, and then grouping them from the viewpoint of usability principles and attributes. This bidirectional approach has two outstanding advantages: it allows thorough examination of potential elements that can cause usability problems from the standpoint of usability attributes, and also derives specific evaluation elements from the perspective of UI design components that are relevant to the real service environment. The evaluation system constitutes a hierarchical structure by networking usability attributes, UI guideline which indicates usability principles for each attribute, and usability evaluation checklist for each UI component that enables specific evaluation. Especially, each evaluation checklist contains concrete contents and format so that it can be readily marked in O/X. The score is based on the ratio of number of items that received positive answer to the number of total items. This enables a quantitative evaluation of the usability of mobile WAP service. The validity of the proposed evaluation system has been proved through comparative analysis with the real usability problems based on the user test. A software was developed that provides guideline for evaluation objects, criteria and examples for each checklist, and automatically calculates a score. The software was applied to evaluating and improving the real mobile WAP service.

• Journal of the Society of Disaster Information
• /
• v.15 no.4
• /
• pp.469-478
• /
• 2019

Purpose: In this studies we examine the facilities damage characteristics caused by forest fire. Therefore, we surveyed damaged facilities from forest fire which was occurred on Goseong-Gun on march 28 in 2019.(damaged areas was 40ha) The types of facilities uses were house, public facility, warehouse and so on. 17 facilities were destroyed. The purpose of this study was to for establishing a disaster safety village in rural areas where damage from a similar type of disaster occurs repeatedly by conducting the consciousness survey targeting at experts and disaster safety officials in a local government. Method: We surveyed meteorological factors(temperature, wind speed, wind direction, humidity) per a minute for analyzing weather condition on Goseong-Gun when forest fire was occurred, spread and extinguished. And we surveyed forest fire risk factors(a slope degree, a slope direction, a geographical feature, a distance between forest and facility, main species, the existence of crown fire ignition, the direction of facility, the main material of building) around 10 damaged facilities. Finally, we analyzed damage pattern of facilities using meteorological factor and forest fire reisk fator Result: The weather condition of Kanseonng AWS (No.517) was high temperature, arid and strong wind, when the forest fire was occurred and spread. An average wind speed was 4.1m/s and the maximum wind speed was 11.6m/s. The main direction of wind was W(225~315°). Damaged facilities were located on the steep slope area and on the mountaintop. The forest density around facilities was high and main species was korean red pine. The crown fire was occurred in the forest around damaged facilities. The average distance was 13.5m from forest to facilities. When the main matarial of building was made by fire resistance materials (for example, rainforced concrete), the damage was slightly. on the other hand, when by flammable material (for example, a Sandwich Panel), the facilities were totally destroyed Conclusion: The results of this research which were the thinning around house, making a safety distance, the improvement of main material of building and etc, will be helpful for establishing a counter measure for a forest fire prevention of facilities in wild land urban interface

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6C
• /
• pp.395-406
• /
• 2006

Drilled shafts are a common foundation solution for large concentrated loads. Such piles are generally constructed by drilling through softer soils into rock and the section of the shaft which is drilled through rock contributes most of the load bearing capacity. Drilled shafts derive their bearing capacity from both shaft and base resistance components. The length and diameter of the rock socket must be sufficient to carry the loads imposed on the pile safely without excessive settlements. The base resistance component can contribute significantly to the ultimate capacity of the pile. However, the shaft resistance is typically mobilized at considerably smaller pile movements than that of the base. In addition, the base response can be adversely affected by any debris that is left in the bottom of the socket. The reliability of base response therefore depends on the use of a construction and inspection technique which leaves the socket free of debris. This may be difficult and costly to achieve, particularly in deep sockets, which are often drilled under water or drilling slurry. As a consequence of these factors, shaft resistance generally dominates pile performance at working loads. The efforts to improve the prediction of drilled shaft performance are therefore primarily concerned with the complex mechanisms of shaft resistance development. The shaft resistance only is concerned in this study. The nature of the interface between the concrete pile shaft and the surrounding rock is critically important to the performance of the pile, and is heavily influenced by the construction practices. In this study, the influences of asperity characteristics such as the heights and angles, the strength characteristics and elastic constants of surrounding rock masses and the depth and length of rock socket, et. al. on the shaft resistance of drilled shafts are investigated from elasto-plastic analyses( FLAC). Through the parametric studies, among the parameters, the vertical stress on the top layer of socket, the height of asperity and cohesion and poison's ratio of rock masses are major influence factors on the unit peak shaft resistance.