• Advances in concrete construction
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• 제14권5호
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• pp.317-330
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• 2022

This paper investigated computationally and experimentally the interaction here between a notch as well as a micropore under uniaxial compression. Brazilian tensile strength, uniaxial tensile strength, as well as biaxial tensile strength are used to calibrate PFC2d at first. Then, uniaxial compression test was conducted which they included internal notch and micro pore. Experimental and numerical building of 9 models including notch and micro pore were conducted. Model dimensions of models are 10 cm × 10 cm × 5 cm. Joint length was 2 cm. Joints angles were 30°, 45° and 60°. The position of micro pore for all joint angles was 2cm upper than top of the joint, 2 cm upper than middle of joint and 2 cm upper than the joint lower tip, discreetly. The numerical model's dimensions were 5.4 cm × 10.8 cm. The fractures were 2 cm in length and had angularities of 30, 45, and 60 degrees. The pore had a diameter of 1 cm and was located at the top of the notch, 2 cm above the top, 2 cm above the middle, and 2 cm above the bottom tip of the joint. The uniaxial compression strength of the model material was 10 MPa. The local damping ratio was 0.7. At 0.016 mm per second, it loaded. The results show that failure pattern affects uniaxial compressive strength whereas notch orientation and pore condition impact failure pattern. From the notch tips, a two-wing fracture spreads almost parallel to the usual load until it unites with the sample edge. Additionally, two wing fractures start at the hole. Both of these cracks join the sample edge and one of them joins the notch. The number of wing cracks increased as the joint angle rose. There aren't many AE effects in the early phases of loading, but they quickly build up until the applied stress reaches its maximum. Each stress decrease was also followed by several AE effects. By raising the joint angularities from 30° to 60°, uniaxial strength was reduced. The failure strengths in both the numerical simulation and the actual test are quite similar.

• Advances in concrete construction
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• 제15권6호
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• pp.419-430
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• 2023

In this study, the effect of two types of aggregates (fly ash aggregate and shale aggregate) on the density, strength, and durability of preplaced lightweight aggregate concrete (PLWAC) was studied. The results showed that the 7 - 28 days strength of concrete prepared with fly ash aggregates (high water absorption rate) significantly increased, which could attribute to the long-term water release of fly ash aggregates by the refined pore structure. In contrast, the strength increase of concrete prepared with shale aggregates (low water absorption rate) is not apparent. Although PLWAC prepared with fly ash aggregates has a lower density and higher strength (56.8 MPa @ 1600 kg/m³), the chloride diffusion coefficient is relatively high, which could attribute to the diffusion paths established by connected porous aggregates and the negative over-curing effect. Compared to the control group, the partial replacement of fly ash aggregates (30%) with asphalt emulsion (20% solid content) coated aggregates can reduce the chloride diffusion coefficient of concrete by 53.6% while increasing the peak load obtained in a three-point bending test by 107.3%, fracture energy by 30.3% and characteristic length by 103.5%. The improvement in concrete performance could be attributed to the reduction in the water absorption rate of aggregates and increased energy absorption by polymer during crack propagation.

• 건축역사연구
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• 제32권4호
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• pp.19-33
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• 2023

This study investigated the architectural expression of Taekpungdang(澤風堂, The Pond and Wind House) built by the Neo-Confucianist Taekdang Lee Sik(澤堂 李植, 1584~1647) from the perspective of the symbolic system of the Zhōuyì(『周易』, Classic of Changes). This study examined the historical context, personal history, and construction process of Taekpungdang at the time of its creation through his collection of writings, the Taekdanggip(澤堂集). The study also estimated the original form of Taekpungdang through field surveys and historical evidence. In addition, the architectural principles and architectural expressions inherent in the Taekpungdang were derived based on the symbolic system of "taekpungdaegwa"(澤風大過) which is Lee Sik's divination and one of the 64 trigrams in the Zhōuyì. Lee Sik, who was knowledgeable in the Zhōuyì, used divination to cope with the chaotic political situation and his own misfortunes. Accordingly, He determined the direction of his life and planned the surrounding environment, architectural structure, and form of Taekpungdang based on the rules and meanings of his divination system. He embodied the architectural space of Taekpungdang with the concept of time and space inherent in the divination of "daegwa",(大過, great exceeding). In addition, he expressed the principle of the generation of palgue,(八卦, the eight trigrams for divination) and the principle of the co-prosperity of ohaeng(五行, the five elements) through the composition of walls and windows of the house. The images of Taekpungdaegwae, which are dongyo(棟撓 wood submerged in the pond) and taekmyeolmok(澤滅木, shaking pillars), were manifested in the form of buildings. Therefore, Taekpungdang can be considered a remarkable example of a building designed through the thorough utilization of the Zhōuyì divination system.

• 한국지구과학회지
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• 제44권4호
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• pp.331-341
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• 2023

The goal of this study was to examine the PCK required for science teachers and PCK required for university teacher educators in terms of school science knowledge, science teaching and learning, and the role of science educators, which are the main axes of science education in future schools, and to explore the relationship between them. This study is a follow-up to a previous stage of research that explored the prospects for changes in schools in the future (2040-2050) in terms of school knowledge, educational methods, and teacher roles. Based on in-depth interviews, qualitative and semantic network analyses were conducted to derive and compare the characteristics of PCK and PCK. As for the main research results, science teacher PCK in future schools should include expertise in organizing science classes centered on convergence topics, expertise in digital platforms and ICT use, and expertise in building a network of learning communities and resources, as part of the expertise of human teachers differentiated from AI. Teacher educators' PCK includes expertise in the research and development of T-L methods using AI, expertise in the knowledge construction process and practice, and expertise in developing preservice teachers' research competencies. Discussed in the conclusion is the change in teacher PCK and teacher educator PCK with changes in science knowledge, such as convergence-type knowledge and cognition-value integrated knowledge; and the need to emphasize values, attitudes, and ethical judgments for the coexistence of humans and non-humans as school science knowledge in the post-humanism future society.

• 한국공간구조학회논문집
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• 제23권2호
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• pp.19-28
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• 2023

Timber structures are susceptible to moisture, contamination, and pest infestation, which can compromise their integrity and pose a significant fire hazard. Despite these drawbacks, timber's lightweight properties, eco-friendliness, and alignment with current architectural trends emphasizing sustainability make it an attractive option for construction. Moreover, timber structures offer economic benefits and provide a natural aesthetic that regulates building temperature and humidity. In recent years, timber domes have gained popularity due to their high recyclability, lightness, and improved fire resistance. Researchers are exploring hybrid timber and steel domes to enhance stability and rigidity. However, shallow dome structures still face challenges related to structural instability. This study investigates stability problems associated with timber domes, the behavior of timber and steel hybrid domes, and the impact of timber member positioning on dome stability and critical load levels. The paper analyzes unstable buckling in single-layer lattice domes using an incremental analysis method. The critical buckling load of the domes is examined based on the arrangement of timber members in the inclined and horizontal directions. The analysis shows that nodal snapping is observed in the case of a concentrated load, whereas snap-back is also observed in the case of a uniform load. Furthermore, the use of inclined timber and horizontal steel members in the lattice dome design provides adequate stability.

• Geomechanics and Engineering
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• 제32권1호
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• pp.69-84
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• 2023

This paper proposes a novel frame element on Winkler-Pasternak foundation for analysis of a non-ductile reinforced concrete (RC) member resting on foundation. These structural members represent flexural-shear critical members, which are commonly found in existing buildings designed and constructed with the old seismic design standards (inadequately detailed transverse reinforcement). As a result, these structures always experience shear failure or flexure-shear failure under seismic loading. To predict the characteristics of these non-ductile structures, efficient numerical models are required. Therefore, the novel frame element on Winkler-Pasternak foundation with inclusion of the shear-flexure interaction effect is developed in this study. The proposed model is derived within the framework of a displacement-based formulation and fiber section model under Timoshenko beam theory. Uniaxial nonlinear material constitutive models are employed to represent the characteristics of non-ductile RC frame and the underlying foundation. The shear-flexure interaction effect is expressed within the shear constitutive model based on the UCSD shear-strength model as demonstrated in this paper. From several features of the presented model, the proposed model is simple but able to capture several salient characteristics of the non-ductile RC frame resting on foundation, such as failure behavior, soil-structure interaction, and shear-flexure interaction. This confirms through two numerical simulations.

• 한국지반환경공학회 논문집
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• 제24권1호
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• pp.37-44
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• 2023

본 연구에서는 도로의 건설 시간 및 유지관리 비용을 단축하기 위하여 제안된 지속가능한 장수명 모듈러 도로시스템의 하부구조인 지지 모듈러의 성능을 평가하였다. 하부 곡선면을 가진 Cross-Beam 형태의 지지 모듈러 4개로 구성된 모듈러 도로시스템을 Test-bed에 시공하였다. 6개의 하중계와 8개의 변위계를 중앙부 2개 Cross-Beam 형태의 지지 모듈러에 설치하였다. 2개의 하중, 50kN, 100kN을 도로 포장슬래브 15개 지점에 재하하여 모듈러 도로시스템에서 발생하는 하중 및 변위를 측정하였다. 측정된 변위들은 1mm 미만으로 실제 도로의 안정성에 문제가 없을 것으로 판단된다. 현장실험에서 적용된 2개의 재하 하중들과 측정된 하중값들을 비교해 보았을 때 하부 지반에 전달되는 하중은 매우 작은 것으로 판단된다. 지지 모듈러를 가진 모듈러 도로 시스템을 실제 도로현장에 적용 가능한 것으로 판단된다.

• 한국지반공학회논문집
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• 제24권10호
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• pp.71-81
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• 2008

토압, 지하수위 상승, 집중호우, 구조적 결함 등 여러 요인들로 인해 발생한 흙막이 벽체의 변위는 배면지반에 변위를 발생시키고, 과다한 지반의 변위로 인해 발생한 구조물의 부등침하는 구조물의 파손이나 파괴를 일으킨다. 이러한 경우, 벽체와 구조물의 보강대책이 강구되어야 한다. 최근 이러한 문제를 최소화하거나, 억제하기 위한 보강대책 중 하나는 마이크로 파일을 이용하는 방법이다. 본 연구는 벽체의 변위로 인해 발생할 인접구조물의 부등침하를 억제시키기 위해 설치한 마이크로 파일의 보강효과의 경향을 파악하고자 실시한 모형실험을 다루고 있다. 실험결과, 마이크로 파일의 설치길이는 2B(B:기초 폭), 간격은 2D(D:파일직경)로 설치하는 경우가 가장 발생한 침하율이 작았다. 또한 이 경우(L=2B, s=2D), 구조물에서 이격거리 0.1B 이내에서 지표면에 수직방향으로 설치할 때가 침하율이 가장 작게 발생하는 것으로 나타났다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2020년도 추계학술대회
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• pp.80-81
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• 2020

코로나 19로 인하여, 전 세계 경제가 위기 상황에 직면해 있으며 수출을 위주로 하는 산업에 대해서는 기업의 생존을 고민해야 하는 상황이다. 정부와 업계에서는 여러 방면으로 수출 활성화를 위해 노력하고 있으며, 비대면 수출 활동에 제약이 발생하면서 비대면으로 수출 마케팅을 실행할 수 있는 여러 방법들을 고민하고 있다. 그중에서도 온라인을 통한 전시회를 진행하는 부분에 대해서 여러 산업에서 다방면으로 연구가 이루어지고 있다. 특히 조선해양 산업은 수출 주력산업으로, 전 세계적으로 개최되는 오프라인 전시회가 마케팅의 중요한 기회의 장이었고, 이를 대체할 수 있는 온라인 전시회 활용이 절실한 실정이다. 본 연구에서는 조선해양 산업에 적합한 온라인 전시장 구축에 필요한 여러 요소 기술들인 AR, VR, MR 등에 대해서 알아보고, 온라인 전시회에 어떻게 접목되는지.

• 대한토목학회논문집
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• 제26권3D호
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• pp.375-383
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• 2006

국회주차장은 지속적으로 증가하는 주차수요와 함께 주차장 이용을 무료로 개방하여 상근자들의 장시간 주차, 국회방문 공무원 및 민간차량의 자가용이용 선호, 국회업무이외에 주변 상가나 오피스 이용차량의 국회주차장 무단 점유 등으로 주차시설의 부족현상이 심화되고 있다. 국회내 주차수요와 공급의 불균형으로 국회내부 및 외부 도로상의 불법주차차량으로 국회주차질서는 매우 무질서하다. 본 연구는 국회의사당의 주차실태 및 이용실태조사를 근간으로 단기적으로 유출 입 관리시스템 구축, 중 장기적으로 국회주차장의 유료화 및 관리운영의 민간위탁, 주차장 상한제 폐지를 통한 입체주차장 건설과 지상주차장의 공원화 방안 등 적극적인 주차관리대책을 제시하였다. 새로운 주차관리대책과 병행하여 상근자 및 방문자의 주차수요를 관리하기 위해 요일제와 부제운행의 강화, 셔틀버스노선 및 통근버스 노선의 확대, 둔치주차장의 이용활성화 방안, 다양한 대중교통이용촉진대책의 시행를 제시하였다. 결론적으로 국회 주차문제는 시설공급보다 주차수요를 관리하는 수요관리정책이 더 적합하다.