• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.47-53
• /
• 2022

As the limit state design method is applied as a method of designing concrete structures, the ultimate state is considered in the analysis or design. In fact, when the reinforced concrete member bears tensile force, the force is transmitted from the rebar to the concrete, and the structure bears the tensile force to the ultimate state even after yield. Therefore, the accurate evaluation of behavior after yield, it is necessary to study the tension stiffening effect after yield of the flexural member. In this study, a 4-point bending test was conducted on the RC simple beam having a rectangular cross section of the double reinforcement, and the behavior of the member was analyzed in detail using the image analysis method. Using the analysis results, the estimation formula for the tension stiffening effect after yield was proposed, and the applicability of this was verified through the experimental results of existing study. The difference between the ultimate strain and the yield strain representing the ductile behavior of the member is similar to the experimental results. The prediction of the proposed formula is relatively accurate.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.843-848
• /
• 2023

The purpose of this study is to understand in detail the development of infants in the 18-24-month period when language develops the most, and to prepare new standards for developmental evaluation that can promote appropriate intervention design at an early time. We divided sub-items such as screening tests and standardized test tools to know the language development ability indicators of infants aged 18-24 months were divided into syntax/phonology, meaning, and speech, and each question was classified and a checklist was made on a five-point scale to conduct a survey on parents with infants aged 18-24 months. Low sensitivity to screening of infants with language delays in nationally implemented infant health checkups, and domestic test tools are standardized for at least six to as many as 10 years, which is always possible in questionnaires related to acceptance and expression, with many reports from parents or teachers.The proportion of "wow" and "started to do" was more than 50-60%. Based on the results of this study, it is hoped that new standards for developmental evaluation will be developed to promote the design of appropriate interventions in detail at a short time.

• International Journal of Highway Engineering
• /
• v.5 no.4 s.18
• /
• pp.23-35
• /
• 2003

In this study, compaction evaluating program based on ASTM critria is developed bu analyzing the results of laboratory tests. And the laboratory tests such as compaction test, triaxial test and resonance column test of subgrade soils are performed to develop compaction management methodology at seven test sites. Especially, to figure out chararteristic with changing compactive efforts, the test was carried out at five levels of compactive efforts at each soil sample. Database was set up from the test results. With the methodology using mechanical property - the elastic modulus, the gap between road design and management and road construction management is narrowed. The regression equation of G/$G_{max}$ is proposed at each strain level of subgrade soils according to AASHTO criteria, and the relationship between fundamental properties of soil mass and degree of compaction is derived as well. The development of compaction management and field compaction management method is proposed by the elastic modulus based on mechanical tests.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.96-104
• /
• 2018

Military vessels are complex weapon systems consisting of various integrated onboard equipment. Since their acquisition of military equipment takes a long period of time and a prototype ship is deployed and tested, vessel development has relied on its proprietary process. However, due to the growing complexity of onboard equipment technology, application of systems engineering (SE) process has become indispensable. Nonetheless, an effective design process complementing the existing design with the SE has not yet been developed. As such, we have studied an improved basic design process for submarines based on SE. To do so, we analyzed the processes for the basic design, technical review, and requirement management. Included reviews and requirements are SRR, SFR and PDR, and SSRS, SSS, and SSDD. By combining the results in the SE framework, we built an improved basic design process that can be applied in parallel with the SE-based technical review and requirement management. To assess the process, we applied our proposed model to the submarine development undergoing the basic design phase. It is possible to effectively manage the requirements, design artifacts and improve traceability, and also utilize them as test and evaluation materials. The SE-based basic design process is expected to be useful in other kinds of vessel design.

• Science of Emotion and Sensibility
• /
• v.24 no.1
• /
• pp.11-24
• /
• 2021

This study investigates the buying behavior pertaining to Japanese brands according to the degree of patriotism of consumers in their 20s. A survey of 235 university students was conducted; the survey questioned the basic purchasing attitudes of consumers in their 20s regarding outerwear and underwear and then surveyed the purchasing attitudes regarding U brand's (representative Japanese brand) outerwear and underwear. To detect the correlation between patriotism and U brand purchases, this study asked questions about patriotism and investigated basic personal information. The research results were as follows. First, there was a significant difference in consumer's purchasing attitude toward outerwear and underwear. When of consumers who are in their 20s purchase outerwear, its design was the most important factor, whereas when purchasing underwear, functionality was the most crucial factor. Second, it was confirmed that consumer's attitudes toward U brand's outerwear and underwear differed. Although the evaluation of U brand's outerwear design was not positive, the consumer tended to be satisfied with the price. U brand's score concerning the functionality of underwear products received a slightly positive response. Third, a total of 235 respondents were divided into a high- and low-patriotism-group based on questions about patriotism. There were significant differences in their attitudes toward clothing and consumer's purchasing behavior at U brand. Highly patriotic consumers thought negatively about U brand outerwear products in terms of price and product quality than low patriotic consumers; however, there was no significant difference only regarding design evaluation. For underwear products, low patriotic consumers were more positive about the price, design, and functionality of U brand products than high patriotic consumers.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.20 no.1
• /
• pp.1-9
• /
• 2010

Objectives : The purposes of this study were to evaluate exhaust ventilation systems(EVSs) and to suggest problems and improvements. Methods : For 50 small and medium-sized enterprises, we carried out evaluation of EVSs. We evaluated hoods with smoke tester and measurement of capture velocity. In addition, we used several indicators for performance evaluation designed in this study. Results : 1. Based on the smoke flow pattern and the criteria of occupational health and safety act, 67.8% of hoods were rated 'good' level at smoke test whereas 26.3% were rated 'good' level at measurement of capture velocity. 2. 29.3% of hoods, of which ratio of measured actual air flow at hood(Qah) to required ideal exhaust air flow at hood(Qih) was 1 or more, were rated 'good' level. 3. The % of EVS, of which ratio of measured actual air flow at stack(Qast) to total required ideal exhaust air flow at hood(Qith) was 1 or more, was 29.0%. 4. For the ratio of measured Qast to existing air flow at fan(Qfan), only 5% of EVSs were 1 or more and 26.0% were 0.8 or more but less than 1.0. 5. For the ratio of measured Qast to total measured actual exhaust air flow at hood(Qath), 74.0% were 0.8 or more but less than 1.0. 6. The percentage of EVS, of which ratio of total measured Qath to existing Qfan was 0.8 or more, was 19.0%. 7. The percentage of EVS, of which ratio of total measured Qath to total required ideal exhaust Qith was 1 or more, was 26.0%. 8. For the comprehensive evaluation indicators designed in this study, 29.0% were 0.8 or more. Conclusions : We found that few exhaust local ventilations at small and medium-sized enterprises were rated 'good' level and that most exhaust local ventilations had 'poor' design and installation. Therefore, relevant professional manpower and enterprises have to construct exhaust local ventilation where it is needed, and technical guidance and economic support are needed to improve 'poor' exhaust local ventilation after self-evaluation.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.1
• /
• pp.15-20
• /
• 2012

Field measurement is a very essential factor for economic aspect and estimation of stability of tunnels. In this paper, various types of support element based on field test data in 4-lane wide road tunnel were evaluated. And stability and economical efficiency were also estimated. The estimated value were compared with design value and the type of support element which is applicable to site condition was evaluated. The results show that most of support elements were modified under the standard value(30mm) and type of support element which is already constructed was overestimated. So, appropriate level of support element have to be presented to save the time and cost during construction.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.5
• /
• pp.641-652
• /
• 2007

In this paper, a half-scaled substructure test was performed to evaluate the buckling and structural safety of an existing transmission tower subjected to wind load. A loading scheme was devised to reproduce the dead and wind loads of a prototype transmission tower, which uses a triangular jig that is mounted on the reduced model to which the similarity law of a half length was applied. As a result of the preliminary numerical analysis carried out to evaluate the stability of a specimen for the design load, is was confirmed that the calculated axial forces of tower leg members were distributed to $80{\sim}90%$ of an admissible buckling load. When the substructured transmission tower was loaded by 270% of its maximum admissible buckling load, it was failed due to the local buckling that is occurred in joints with weak constraints for out-of-plane behavior of leg members. By inspection of load-displacement curves, displacements and strains of members, it is considered that this local buckling was due to additional eccentric force by unbalanced deformation because the time that is reached to yielding stress due to the bending moment is different at each point of a same section.

• Journal of Ocean Engineering and Technology
• /
• v.28 no.2
• /
• pp.133-139
• /
• 2014

Offshore wind turbines have been constructed extensively throughout the world. These turbines are subjected to approximately $10^8$ horizontal load cycles produced from wind, waves, and current during their lifetimes. Therefore, the accumulated displacement of the foundation under horizontal cyclic loading has significant effects on the foundation design of a wind turbine. Akili(2006) and Achmus et al.(2009) performed cyclic triaxial tests on dry sands and proposed an empirical model for predicting the accumulated plastic strain of sands under long-term cyclic loading. In this study, cyclic triaxial tests were performed to analyze the cyclic loading behaviors of dry sands. A total of 27 test cases were performed by varying three parameters: the relative density of the sands, cyclic load level, and confining stress. The test results showed that the accumulated plastic strain increased with an increase in the cyclic load level and a decrease in the relative density of the sand. The confining stress had less effect on the plastic strain. In addition, the plastic strain at the 1st loading cycle was about 57% of the accumulated strain at 1,000 cycles. Finally, the input parameters of the empirical models of Akili(2006) and Achmus et al.(2009) were evaluated by using the relative density of the sand and the cyclic load level.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.15 no.4
• /
• pp.8-15
• /
• 2019

In order to design coaxial-type Ground Heat Exchangers (GHEXs) efficiently, the effect of components (i.e, heat exchange pipe and grouting material) on the thermal performance of coaxial-type GHEXs should be identified in advance. In this paper, three coaxial-type GHEXs with different configurations were constructed in a test bed. Then, the effect of heat exchange pipes and grouting materials on the thermal performance of coaxial-type GHEXs was investigated by performing in-situ thermal response tests (TRTs) and thermal performance tests (TPTs). In the TRTs, the effective thermal conductivities of the coaxial-type GHEXs with concrete grouting and STS pipes were improved by 6.15 and 22.7%, respectively compared to those of bentonite grouting and HDPE pipes. Additionally, in the TPTs, the use of concrete grouting and STS pipes in the coaxial-type GHEXs enhanced the in-situ thermal performance by 15 and 33.8%, respectively.