본 연구에서는 탄소나노튜브/화이버/폴리머 복합소재 구조에 대한 재료 물성 및 강성 추정을 다룬다. 수정된 Halpin-Tsai 모델을 적용한 멀티 스케일 해석은 탄소나노튜브의 함유량 비율, CNT 두께-길이 비율, 화이버 부피 함유량, 그리고 화이버 보강각도 변화에 따라서 수행되었다. 본 연구에서 제시한 멀티-스케일 접근방법은 기존 모델을 적용하여 얻은 결과와 비교하여 검증하였다. 매개변수 해석을 통하여 CNT의 적절한 함유량은 적층된 CNTFPC 구조의 구조성능의 향상시킬 수 있는 중요한 특성을 규명하였다.

본 연구에서는 KS 강종 규격 YS245(SS400)에서 YS275(SS275)로 개정됨에 따라 고속구간에 설치하는 SB3-B등급에 대하여 탑승자보호성능 평가 및 강도성능 평가를 위한 충돌시뮬레이션을 수행하였다. 시뮬레이션은 소형차에 대하여 탑승자 보호성능평가항목인 탑승자 충격속도 및 탑승자 가속도를 평가하고, 대형차에 대해서 강도성능을 비교 분석하기 위하여 비선형 유한요소 동적 해석을 수행하였다. 수치해석 예제로부터 YS275 강종은 기존강재에 비하여 전반적으로 우수한 충돌 성능을 보였으며, 특히 PHD의 개선효과가 상대적으로 더욱 우수함을 알 수 있었다. 본 연구에서 적용한 솔리드 지반-구조물 상호작용 모델은 지진해석으로 적용할 수 있다.

A parametric study was carried out to gain an insight about structural performances considering abnormal behavior effects in high strength steel pipe strut system. Six load cases were considered as undesirable deflections of strut structures, which are basic load combination, excessive excavation situations, impact loading effects, additional overburden loads, load combinations, and 50% reduction of strut length. Subsequent simulation results present various influences of parameters on structural performances of the strut system. Based on the results, we propose methods to prevent unusual behaviors of pipe-type strut structures made of high strength steels.

The flow of the 4th Industrial Revolution calls for fundamental changes in the way of business pursued by manufacturing companies. In the service industry, various business models have been developed to include tangible products in services in order to secure differential competitive advantage in the market. Discussion of servitization and productization in academic research reflect the trends of these industries, and related researches are widely carried out in business administration, engineering, and design fields. In the meantime, customer value created by manufacturing companies and service companies has been proposed mainly about function, quality and utility of products or services. However, E3 Value (economic, ecological, experience), which is discussed from the viewpoint of product-service system (PSS), is newly recognized as an important factor in creating customer value. The purpose of this study is to develop a measurement model for the effects of product value, service value, and newly illuminated E3 Value on various business performance of a company. This study suggests a research model to extend the discussions on E3 Value, which was limited to concept studies and case studies, to empirical studies.

This study performs material nonlinear analysis of connection parts at noise barriers, which have a light weight. Subsequent numerical simulation results for three types of models (standard, double, and standard models strengthen by ribs) present that the applied connections for target noise barriers constructed show suitable structural performance. In this paper, the existing finite element elastic stress analysis using the ABAQUS program is further extended to study the plastic stress distribution of the noise barriers. The numerical results for various parameters are verified by comparing different steel types with stresses occurred in the noise barrier from the numerical simulation.

A parametric study was carried out to gain an insight about structural performances considering abnormal behavior effects in high strength steel pipe strut system. Six load cases were considered as undesirable deflections of strut structures, which are basic load combination, excessive excavation situations, impact loading effects, additional overburden loads, load combinations, and 50% reduction of strut length. Subsequent simulation results present various influences of parameters on structural performances of the strut system. Based on the results, we propose methods to prevent unusual behaviors of pipe-type strut structures made of high strength steels.

A finite element impact simulation study was performed to assess structural performances of a guard-rail system for roadside using new steel materials (SS275) in the KS standard. The type SS275 shows an enhanced tensile strength in comparison with the former type SS400. Subsequent simulation results present that the improved model performs much better in containing and redirecting the impacting vehicle in a stable manner. The numerical results for various parameters are verified by comparing different models with dynamic responses determined in the barrier from the crash simulation.

We carried out a dynamic instability assessment of carbon nanotube reinforced composite (CNTRC) and carbon nanotubes/fiber/polymer composite (CNTFPC) skew plates based on the high-order shear deformation plate theory (HSDT). The multiscale interactions between carbon nanotube (CNT) ratios and skew angles on the dynamic instability for various length-thickness ratios are studied using a two-dimensional finite element model developed for this study. The results were verified by those reported in the literature show the interactions between the CNT reinforcement and skew angles in the skew laminate. Numerical examples show the importance of CNT reinforcement when assessing the dynamic instability of CNTRC and CNTFPC skew plates.

As the competitiveness of SMEs (small and medium enterprises) is getting more and more improved and globalized, the government provides various consulting services to secure the competitiveness of small and medium firms and support stable growth. However, the assessment of the result from the government’s support is generally focused on non-financial factors, such as customer satisfaction and analysis of improvement effect. This paper is in regards to the statistical analysis of how much the government’s support in the form of providing consulting services contributes to financial outcomes in terms of profitability and growth. ROA (return on asset) and ROS (return on sales), which are investment profitability and sales profitability respectively, are chosen as an indicator of profitability. For analysis of growth, sales revenue and total asset growth are used. The samples are 44 corporations which are supported by government, and 150 corporations which are selected for comparison, with corporate growth support center program by the Ministry of Trade, Industry, and Energy chosen as the consulting model. After gathering the yearly balance sheets and income statements of the samples from CRETOP, Korea Enterprise Data, the analysis is conducted in the way of identifying the statistical significance of financial difference in the same period between corporates taking consulting services and corporates which have not, and the difference of financial outcomes from the corporates taking consulting services before and after consulting services. As a result, in terms of business growth, it is turned out to have positive difference both in growth ratio and profitability compared to the compared corporations at the significant level. Therefore, it is obvious that the consulting program which government provides to SMEs have direct influence practically to the corporates’ management performance.

As the competitiveness of small and medium businesses is getting more and more improved and globalized, the government provides various consulting services to secure the competitiveness of small and medium firms and support stable growth. However, the assessment of the result from the government’s support is generally focused on non-financial factors, such as customer satisfaction afterwards and analysis of improvement effect. This paper is in regards to the analysis of how much the government’s support in the form of providing consulting services contributes to financial outcomes and to the analysis of the gap of performances among the types of consulting services. We verified the statistical significance of our hypothesis through SAS9.4 and SPSS 22, conducting comparative analysis of the business growth and profitability based on the yearly balance sheets and income statements of 44 corporations which government supports and 150 corporations which are for comparison. The data is gained from CRETOP, Korea Enterprise Data, and the testing model is chosen as the business of support center for corporate growth, which is a customized supporting business of the Ministry of Trade, Industry, and Energy. As a result, in terms of business growth, it turned out to have positive difference in growth ratio compared to the industrial average and compared corporations and to have significant difference in terms of profitability as well. Since, this paper shows that the different supporting ways have significant difference, we would say that this paper is meaningful in that it may propose a guidance for government to set strategies of government-supporting businesses.

This study performs finite Element stress analysis of flange connections at noise barriers with circular steel tubes, which have a light weight. Subsequent numerical simulation results for three types of models (standard, double, and standard models strengthen by ribs) present that the applied connections for target noise barriers constructed show suitable structural performance. In this paper, the existing finite element stress analysis using the ABAQUS program is further extended to study the local stress distribution of the noise barriers with new type circular steel tubes. The numerical results for various parameters are verified by comparing different types with stresses occurred in the noise barrier from the numerical simulation.

This study dealt with truck crash performance evaluation of new guardrails made of PosMac steels considering the ground bearing capacity effect. Subsequent crash simulation results for SB2 and SB4 grades present that the developed model performs much better in containing and redirecting the impacting vehicle in a stable manner. In this paper, the existing finite element crash analysis of guardrails using the LS-DYNA program is further extended to study the nonlinear dynamic response of the guardrail structures with new type poles supported by external stiffeners. The numerical results for various parameters are verified by comparing different grades with displacements occurred in the barrier from the crash simulation.

선박에 설치되는 개구(Opening)는 사람이 드나드는 문(door)과 화물 출입구(cargo access hatch) 그리고 닫힌 장소에 사람이 드나들기 위한 맨홀(manhole)이 있다. 특히 해치는 수밀이 필요한 경우가 많아 폐쇄장치가 복잡한 기구로 구성되게 된다. 이 연구에서는 생산효율 및 품질향상을 위해 유압으로 작동하는 취부용 지그(JIG)를 개발하였다.

Thermographic imaging based non-destructive evaluation proceeds measuring the defect or internal condition of civil structures. To demonstrate the feasibility of the method, the infrared camera system is applied to various specimens. The technique described in this paper may allow us to find their numbers, locations, and the extent of damaged steels from the measurement in the long distance. In addition, a reinforced concrete specimens with different penetration depths is tested using the active thermography method, and to study the influence on the detecting internal rebar in cooled and heated conditions. The experimental results demonstrate that thermographic imaging method is useful for detecting the damage of steel structures and the unknown rebar in the concrete.

This paper dealt with the applicability of GFRP materials as reinforcements for a steel box girder bridge deck. The purpose of this study is to provide detailed design procedures with a code-based text for GFRP composites for civil engineering structures. From the example design, the deck was optimized from a serviceability perspective but was quite overdesigned with regard to flexural strength and creep rupture stress, due to its relatively low longitudinal modulus but high strength. We may conclude from these results that it is advisable to check the serviceability limits before optimizing the design for strength or starting the design from the serviceability calculation.