• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.432-433
• /
• 2011

Even though Korea has very low possibility that a big earthquake occurs like in Japan, China, Taiwan and United States of America, because it is located on the interior of Eurasian Plate, the earthquake which was struck northeast Japan in March 11th, 2011 gave a big shock to Korean. And small-medium earthquakes have been observed 922 times in Korea since 1978 when an earthquake hit Hong-seong and a seismographic station started observation. Moreover, the number of quakes has been on the increase. In case a big earthquake occurs like in northeast Japan, it would be a terrible disaster for Korean power utilities and brings mega effects on Korean society and economy. So it is necessary to apply anti-earthquake design for new power facilities and to reinforce existing facilities. Therefore, this paper would present anti-earthquake design for transmission line and substation and reinforcement measures for existing facilities.

• Journal of the Korean Society for Railway
• /
• v.9 no.2 s.33
• /
• pp.160-168
• /
• 2006

The major objective of this study is to investigate the effects and application of external post-tensioning method far steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis, field test and laboratory test fur the lateral dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the lateral dynamic response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease lateral acceleration and deflection on steel plate girder bridge for serviceability. And the external post-tensioning method reduce dynamic maximum displacement(about $10{\sim}24%$), the increase of dynamic safety is predicted by adopting external post-tensioning method. From the dynamic test results of the servicing steel plate girder bridge, it is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method The servicing steel plate girder bridge with external post-tensioning has need of the reasonable reinforcement measures which could be reducing the effect of lateral dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.514-521
• /
• 2006

In strengthening structure, the external post-tensioning method which secure clearness in the structure analysis process is adopted to bridge as well as architecture structure. Therefore, the major objective of this study is to investigate the effects and application of external post-tensioning method for steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis and laboratory test for the dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease stress and deflection on steel plate girder bridge for serviceability. It is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method. The servicing steel plate girder bridge with external post-tensioning is the reasonable reinforcement measures which could be secured the stability of dynamic behavior and increase a dropped durability.

• Advances in concrete construction
• /
• v.1 no.3
• /
• pp.201-213
• /
• 2013

While recognizing the problem of reinforcement corrosion and premature structural deterioration of reinforced concrete (RC) structures as a combined effect of mechanical and environmental actions (carbonation, ingress of chlorides), emphasis is given on the effect of the latter, as most severe and unpredictable action. In this study, a simulation tool, based on proven predictive models utilizing principles of chemical and material engineering, for the estimation of concrete service life is applied on an existing reinforced concrete bridge (${\O}$resund Link) located in a chloride environment. After a brief introduction to the structure of the models used, emphasis is given on the physicochemical processes in concrete leading to chloride induced corrosion of the embedded reinforcement. By taking under consideration the concrete, structural and environmental properties of the bridge investigated, an accurate prediction of its service life is taking place. It was observed that the proposed, and already used, relationship of service lifetime- cover is almost identical with a mean line between the lines derived from the minimum and maximum critical values considered for corrosion initiation. Thus, an excellent agreement with the project specifications is observed despite the different ways used to approach the problem. Furthermore, different scenarios of concrete cover failure, in the case when a coating is utilized, and extreme deicing salts attack are also investigated.

• Korean Journal of Construction Engineering and Management
• /
• v.24 no.5
• /
• pp.73-82
• /
• 2023

Optimization of Construction Site Layout Planning (CSLP) heavily relies on workers' travel paths. However, traditional path generation approaches predominantly focus on the shortest path, often neglecting critical variables such as individual wayfinding tendencies, the spatial arrangement of site objects, and potential hazards. These oversights can lead to compromised path simulations, resulting in less reliable site layout plans. While Deep Reinforcement Learning (DRL) has been proposed as a potential alternative to address these issues, it has shown limitations. Despite presenting more realistic travel paths by considering these variables, DRL often struggles with efficiency in complex environments, leading to extended learning times and potential failures. To overcome these challenges, this study introduces a refined model that enhances spatial navigation capabilities and learning performance by integrating workers' visibility into the reward functions. The proposed model demonstrated a 12.47% increase in the pathfinding success rate and notable improvements in the other two performance measures compared to the existing DRL framework. The adoption of this model could greatly enhance the reliability of the results, ultimately improving site operational efficiency and safety management such as by reducing site congestion and accidents. Future research could expand this study by simulating travel paths in dynamic, multi-agent environments that represent different stages of construction.

• Geomechanics and Engineering
• /
• v.34 no.3
• /
• pp.285-301
• /
• 2023

During the construction of E75 highway through Grdelica gorge in Serbia, a major failure occurred in the zone of reinforced rock slope. Excavation was performed in highly anisotropic Paleozoic schist rock formation. The reinforcement consisted of the two rows of micropile wall with pre-stressed anchors. Forces in anchors were monitored with load cells while benchmarks were installed for superficial displacement measurements. The aim of the study is to investigate possible causes of instability considering different probability distributions of the strength of discontinuities and anchor bond strength by applying different optimization techniques for finding the critical failure surface. Even though the deterministic safety factor value is close to unity, the probability of failure is governed by variability of shear strength of anisotropic planes and optimization method used for locating the critical sliding surface. The Cuckoo search technique produces higher failure probabilities compared to the others. Depending on the assigned statistical distribution of input parameters, various performance functions of the factor of safety are obtained. The probability of failure is insensitive to the variation of bond strength. Different sampling techniques should yield similar results considering that the sufficient number of safety factor evaluations is chosen to achieve converged solution.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.5
• /
• pp.109-116
• /
• 2010

Infiltration and the rising level of groundwater caused by rainfall are a major cause of the landslide and sliding. In order to secure the safety factor of slope, the slope stabilization and reinforcement works are used to enhance consistency. Nailing, Slope Drainage method and the surface vegetation measures can be simultaneously applied in the Mass Nail method, which is also environmental friendly reinforcement method. To demonstrate the reinforcement effect of a strengthened slope by Mass Nail, the changes in water contents by rainfall were considered while performing Scale Model Test. As a result, safety factor of reinforced slope was about 1.4~2.3 times increased on the unstrength slope. In the case of increasing water content 10% to 22%, The maximum stress was reduced to 12%~24% at the average rate of 18% on the unstrength slope and the reinforced slope by the Mass Nail Method was reduced to 4%~23% at the average rate of 14%.

• Fire Science and Engineering
• /
• v.34 no.4
• /
• pp.87-95
• /
• 2020

This study evaluates the safety of an asylum through a fire simulation of building Type traditional markets. We derive the building's indoor temperature, use the observed variation in temperature gradient to calculate the temperature of the main structure, and finally compares the time required to attain the limit temperature of the structure its time of escape. To ensure improved security of the asylum, the government has proposed a fire-resistance improvement plan for the major structural parts of buildings are not safe with thickness of 0.01 m and 0.035 m. F.ire-resistance reinforcement for small - and medium-sized vehicles is more than 0.025 m, in thickness; moreover safety can be ensured for medium and large-sized vehicles fire using fire resistant reinforcement of over 0.035 m. Accordingly, in order to ensure the safety of an asylum, fire-resistant reinforcement measures may be considered.

• Journal of Korean Academy of Nursing
• /
• v.49 no.2
• /
• pp.137-148
• /
• 2019

Purpose: This study aimed to investigate the effects of a reinforcement program for behavioral skills in postpartum care for couples with their first baby. Methods: The study used a non-equivalent control group and pretest-posttest design. It was conducted from January 14 to April 10, 2016 at a postpartum care center in D city. It analyzed 43 couples (22 in the experimental group and 21 in the control group.) For data analysis, descriptive statistics, test of homogeneity in pretest, independent t-tests, and repeated measures ANOVA were used. Results: For maternal fulfillment of postpartum care and postpartum fatigue, there was no significant difference in the interaction between group and time. In terms of parent-newborns attachment, the interaction between group and time showed a significant difference for mothers (F=13.63, p=.001) and fathers (F=6.51, p=.001). In marital intimacy, the interaction between group and time showed a significant difference for mothers (F=14.40, p<.001) and fathers (F=9.46, p=.004). In parenting stress, the interaction between group and time showed a significant difference for mothers (F=31.8, p<.001) and fathers (F=11.69, p=.001). A significant difference was found for the mothers' postpartum sleeping hours (F=0.14 p=.004). Conclusion: This program for behavioral skills in postpartum care, which is based on the information-motivation-behavioral skills model, improves postpartum care, parent-newborn attachment, marital intimacy, parenting stress, and maternal postpartum sleeping, by reinforcing behavioral skills required for postpartum care.

• International Commerce and Information Review
• /
• v.14 no.1
• /
• pp.301-314
• /
• 2012

To improve support for damages due to FTA and competitive power to overcome it, direct damages to farming and fisheries are compensated through Direct Payment Policy and Business Cessation Support System. Support plans will be developed to enhance competitive power in industries and income base in rural areas. This study carried an AHP to decide Priority and Evaluation Criteria in respect to domestic support measures according to FTA. For the AHP, the classes were categorized into direct damage conservation, higher competitive power and expansion of income. For the direct damage preservation measures, the classes were categorized into farmers, fishermen, manufactures, service business managers, and workers. In respect to reinforcement of competitive power of each industry, the classes were categorized into farming, fisheries, manufacturing, the drug industry, and service business. In respect to expansion of income, the classes were categorized into farming and fishing. Then 27 national support measures were presented for sub-classes. As a result of the analysis, it was discovered that more weight was given to measures to reinforce competitive power of each industry and expand income than those on direct damage conservation. In respect to higher competitive power in industries, more weight was given to support for farming and manufacturing. In respect to expansion of income, more weight was given on measures on farming than fisheries. For the direct damage preservation measures, more weight was given on support measures on farmers and workers.