• Geotechnical Engineering
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• v.5 no.1
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• pp.7-18
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• 1989

In pile load tests on end bearing piles, generally, it is not possible to continue loading to the ultimate load. Thus, the concept of yield load has been introduced for determining design loads Iron the pile load test records. The conventional rules to determine the yield load were not available for evaluation on pile load test records obtained in 6 fields nearby westers 8r Southern Coasts in Korea. A new rule 9.as presented to determine easily the yield load, based on investigations on the pile load test records. The yield load of piles is determined at the infiection point on semi-logarithmic coordinates (P-logS), in which load is plotted in normal scale and settlement is plotted in logarithmic scale. This method may not only save much costs and times but also present safe luorking circumstances for pile load tests in field. It was found that the yield load represented the elastic limit of the pile load-settlement behalf.iota. The ultimate load, which is given at 25.4mm settlement on pile head, was 1.5 times of the yield load. The allowable long-term and short-term load capacities were, respectively, 50% and 75% of the yield load. The safety factors to get the allowable pile capacity were obtained as 2.0~4.0 for the equations to predict the static pile capacity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.262-269
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• 2021

This paper conducts an evaluation of the structural performance of the lap splice detail of SD700 headed bar experiment for developing an RC beam with different depths joint details. The experiment variable is lap splice length, yield strength, and end anchorage of main reinforcements. For all specimens, a headed bar was applied to the main reinforcement of the beam with low depth (B2), and the beam with high depth (B1) was applied to the main reinforcement with two splice methods: straight headed bar and 90° hooked-headed bar. The experimental results were that specimens of applying SD500 and SD600 had the results of flexural fracture at the lap splice location, which maximum load was similar. For specimens of appling SD500, the 90° hooked-headed bar of B1, suppressed horizontal cracks in the lap splice section compared to the straight headed bar. Specimens of applying an SD 700 headed bar had the results of brittle anchorage failure. In addition, maximum load was increased with the lap splice length increasing. For specimens of applying SD700 headed bar, test for test maximum load/theoretical load for test development length/design development length were estimated to be 1.30~1.48 for the ACI 318-19 equation, and 1.14~1.30 for the KDS-2021 equation. Thus, ACI 318-19 equation had conservatively greater safety factors as estimated development lengththened.

• The Korean Journal of Emergency Medical Services
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• v.26 no.3
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• pp.161-184
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• 2022

Purpose: This study aimed to develop a cardiopulmonary resuscitation training program for firefighters (FD-CPR) to help improve the survival rate after cardiac arrest on the fireground. Methods: The FD-CPR was developed following 3 steps of the FD-CPR instructional design based on the behaviorism theory. The content of the program was validated by a group of 7 experts using the contents validity index (CVI) and through a pilot-test. Results: A scenario consisting of 7 procedures, and a skill performance evaluation tool consisting of 16 questions were developed. The evaluation tool average score for the difficulty test was 41.16% (even) and that for the discrimination test was 0.32 (high). Subsequently, an 80 min training program was developed. As verified by the 7 experts through the CVI, it was as high as 1.0. Conclusion: The FD-CPR developed domestically for the first time in this study was effective in enhancing the CPR performance skills of the firefighters. If FD-CPR is added to the curriculum at the Fire Service Academy educational course for the new firefighters, the CPR performance skills could be maintained. Furthermore, the program can facilitate a better survival rate for colleagues having cardiac arrest on the field.

• Journal of the Korean Geotechnical Society
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• v.39 no.4
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• pp.31-44
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• 2023

A base expansion micropile was developed to improve the bearing capacity of the micropile, which bears a simple device installed at the pile base. Under an axial load, this base expansion structure radially expands at the pile tip and attaches itself around ground, compressing the boring wall in the construction stage. In this study, conventional and base expansion micropiles were constructed in the weathered rock where micropiles are commonly installed. Further, field load tests were conducted to verify the bearing capacity enhancement effect. From the load test results, it was revealed that the shaft resistance of base expansion micropiles was about 12% higher than that of conventional micropiles. The load transfer analysis results also showed that compared to conventional micropiles, the unit skin friction and unit end bearing of base expansion micropiles were 15.4% and 315.1% higher, respectively, in the bearing zone of the micropile.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.312-329
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• 2024

In various underground research projects such as energy storage and development and radioactive waste disposal targeting deep underground, the characteristics of permeable rock fractures that serve as major pathway of groundwater flow in deep rock aquifer are considered as an important evaluation factor in the design, construction, and operation of research facilities. In Korea, there is little research and database on the location and hydraulic characteristics of permeable rock fractures and the pattern of groundwater flow patterns that may occur between fractures in deep rock boreholes. In this paper, the hydraulic characteristics of permeable rock fractures in deep rock aquifer were evaluated through the analysis of geothermal gradient and pumping test data. First, the deep geothermal distribution was identified through temperature logging, and the geothermal gradient was obtained through linear regression analysis using temperature data by depth. In addition, the hydraulic characteristics of the fractured rock were analyzed using outflow temperature obtained from pumping tests. Ultimately, the potential location and hydraulic characteristics of permeable rock fractures, as well as groundwater flow within the boreholes, were evaluated by integrating and analyzing the geophysical logging and hydraulic testing data. The process and results of the evaluation of deep permeable rock fractures proposed in this study are expected to serve as foundational data for the successful implementation of underground research projects targeting deep rock aquifers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.310-315
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• 2017

Although studies evaluating the effects of the blasting vibration on the adjacent structures from various angles have continued, cases of securing the safety of the adjacent buildings and researching the proper blasting method for the field condition by analyzing the vibration waveform of the measuring field while performing the open pit blasting are poor. Therefore, it is necessary to present a remedy for blasting pattern selection through test blasting that is appropriate for field conditions, and is economical and efficient. In this study, open pit blasting work was conducted based on the separation distance applied according to the standard blasting method by test blasting and the vibration regulation standard in the road expansion construction site to measure the blasting vibration value, and the vibration prediction equation by blasting methods was examined using a regression analysis computer program to calculate K, N, and R of the confidence level 95%. By setting the blasting allowed vibration standard of the test blasting target area to 0.3cm/sec, and the charring weight and blasting method by the separation distances according to the blasting vibration estimation equation of the open pit blasting guideline and the blasting vibration estimation equation of the test blasting were compared/analyzed, it was possible to identify the factors that increased the working expenses. In addition, the measurement and analysis of the adjacent structures during open pit blasting and the blasting vibration were performed after selecting the most adjacent structure to the open pit blasting spot to analyze the problems on the test blasting procedure and analysis method in the open pit blasting design/construction guidelines, which appeared in the process of completing open pit blasting construction, and a remedy is presented.

• The Journal of Korean Association of Computer Education
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• v.22 no.6
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• pp.43-55
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• 2019

In the Fourth Industrial Revolution, a super-intelligent and super-connected society has arrived. Software is an important part of the core technologies of the Fourth Industrial Revolution. The ability to solve problems through software requires software education in that it is a core competency that everyone should have. Software education aims to improve Computational Thinking, which is the ability to solve problems through programming. Until now, most problem-solving programming learning models follow the traditional method of development: Waterfall model (Analysis-Design-Development-Test). In this model, if there is a problem in the preceding step, That could be found in the test phase. This takes a considerable amount of time and effort to find a solution to the problem and can be a burden on the programming learning. In this study, we proposed a Test-Driven Problem-Solving learning model using TDD (Test Driven Development) as Agile development method, and reviewed the appropriateness of the model through experts review. The verification results of the model showed positive evaluation results. In particular, the learning phase configuration of the model, helping in programming learning, helping of Computational Thinking improvement showed high rating, it is determined that there will be positive effects on Computational Thinking improvement through problem-solving programming learning when applying future learning.

• International Journal of Highway Engineering
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• v.5 no.3 s.17
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• pp.31-42
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• 2003

The KHC Test Road project was initiated on 1991 to develop Korean Pavement Design Guide. It was constructed along the Joongbu Inland Expressway line between Yeoju and Gamgok. It is two-lane wide expressway containing fifteen asphalt and twenty-five Portland cement concrete test pavement sections. Various sensors were installed in the Test Road to evaluate the behavior of test pavement sections under the influence of traffic load and environmental change. The most important issues in the sensor installation are the accurate location and long-term survivability. They are directly influenced by the sensor installation methodology. The methodology for asphalt strain gages is mainly discussed in this paper because it is the second important sensors in the KHC Test Road project. In order to find the best methodology, we evaluated existing methodology from prior experience and several conducted test installations. We have tried mound, block out, and trench cuts since 2000. Among three methods, block out was the most effective one in terms of accurate location, long-term survivability, and material homogeneity. However, this method cannot be applied to the wearing coarse so that the mound method was used as an alternative. The block out method was applied to base and intermediate layers while the mound method was used to the wearing coarse. Three hundred seventy-four asphalt strain gauges were installed on asphalt pavement sections from September 3rd to November 18th in 2002. According to the sensor measurement evaluation, 6.3% of sensor demonstrated over ranged readings for mound method installation and 2.5% did for block out method installation. We lost only two sensors during the installation. It is 99.5% survival and it is excellent survival rate according to other experience.

• Composites Research
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• v.36 no.2
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• pp.132-139
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• 2023

A linerless composite propellant tank was designed and manufactured by using the carbon fiber-reinforced composite materials which have superior strength-to-weight ratio in order to reduce weight of the tank. In this research, we designed a sub-scale composite propellant tank with a diameter of 800 mm to withstand an MEOP of 1.7 MPa. We manufactured the boss of the tank by using the same composite materials to reduce the thermal expansion difference between the boss and the secondary-bonded composite layers of the barrel in the cryogenic environment. We used the collapsible mandrel to manufacture the tank without any liner. The mandrel was made from epoxy-based composite tooling prepregs to reduce weight of the mandrel. We manufactured the test tanks by laying up the carbon fiber fabric prepregs manually on the mandrel and then applying the autoclave cure process. We performed a proof test, a helium tightness test, a repeated pressurization test, and a burst test in room temperature. The test results demonstrate that the proposed design and manufacture process satisfies all strength requirements as well as an anti-leakage requirement.

• Journal of Distribution Science
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• v.13 no.11
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• pp.93-100
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• 2015

Purpose - The objective of this research is to investigate whether national culture influences consumers' service evaluations. The services industry is receiving increasing attention from academia and practitioners as its position grows in global markets. Standardization or localization is a traditional managerial decision in global business. As the boundaries of services expand across national borders, firms are required to decide whether to standardize services or adjust to local needs. Though it is imperative to reflect global perspectives in marketing theories, these perspectives are mostly based on Western conceptualization of the world. Through a comparison of consumer groups from two culturally remote countries, service quality evaluation mechanisms are examined based on similar stimuli. The study tries to expand service marketing perspectives across national borders. Research design, data, and methodology - Eastern and Western countries are known to be culturally distinct. One Eastern and one Western country were chosen: an Anglo-Saxon country (the U.S., England, and Australia) and South Korea. In Hofstede's cultural dimensions, the differences between the two are pronounced. The Anglo-Saxon based countries share many similarities. Samples of the same sites are targeted. Questionnaires using a service quality scale (SERVQUAL) and a customer satisfaction scale were distributed. Utilizing Hofstede's typology of culture, the service evaluation mechanisms of the respondents from the two groups are evaluated. Three hypotheses are proposed from the review of the literature. These are service evaluation habits, importance of service quality dimensions for the individualistic/collectivistic countries, and strong/weak uncertainty avoidance cultures. Consumers from the individualistic countries are considered to care about themselves and demand a higher level of responsiveness and assurance. On the other hand, consumers from high uncertainty avoidance cultures are assumed to rely more on tangible questions of service quality, as these are the only predictable service quality indicators. A t-test and regression analysis are applied to validate the constructs. Results - The respondents from the Anglo-Saxon countries are more generous on service evaluations than Koreans. Researchers have indicated that Americans tend to give higher service evolution scores than European, Mexican, and Korean counterparts. The tendency is the same here. The sample from Anglo-Saxon countries demonstrated higher service evaluation scores on every dimension of SERVQUAL. For the second hypothesis, the respondents from the collectivistic culture rely less on core service dimensions (assurance and responsiveness) due to their tendency to place more value on group harmony than individual interest. However, the third hypothesis was not validated. Conclusions - The study attempted to expand the scope of service marketing to reflect cross-national perspectives. Service quality is known to have a strong influence on customer satisfaction and loyalty behavior. However, this research demonstrated that individuals from different cultural territories respond heterogeneously to the same stimuli. Scholars argue that national cultures are main factors in such deviated behavior. Scholars and global managers should be aware of differences in consumer value judgment mechanisms such as satisfaction, expectations, and perceptions.