• 한국전자통신학회논문지
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• 제16권6호
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• pp.1223-1230
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• 2021

최근 에너지 자원관리는 전 세계적인 주요 관심사이다. 에너지원 생산의 한계 조건 속에서, 효과적인 에너지 관리 활동은 에너지 수요 및 생산을 최소화하고 이는 환경이 미치는 영향을 최소화할 수 있다. 본 논문은 주거형 건물에서 에너지 소비자에게 전기 사용에 대한 실시간 정보를 제공할 수 있는 가정용 전기에너지 모니터링 시스템의 프로토타입 설계를 제안하고자 한다. 제안된 시스템은 자체 개발된 센싱 시스템, 데이터처리시스템, 원격 모니터링 서버 시스템으로 구성된다. 주거형 건물내에 설치 적용된 센싱 시스템은 전원 공급을 제어하는 릴레이, 부하 전기기기의 전류를 감지하는 CT센서, Kmote로 구성된 무선 스마트 플러그로 구성된다. 공동/단독 주거형 건물에서 3개월 동안의 가전제품별 에너지 소비량 데이터를 분석하여 제시하였으며, 실험결과는 에너지 소비 패턴과 현황을 추정할 수 있는 가능성을 확인하여 제시하고 있다.

• 한국전산구조공학회논문집
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• 제35권2호
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• pp.119-129
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• 2022

초고층 건물에서 수평변위 제어와 수직부재에서 발생하는 부등축소에 대한 검토가 필수적이다. 이러한 부등축소는 비구조요소의 사용성과 구조요소의 안전성에 대해 문제를 야기할 수 있다. 따라서 이 연구에서는 120층 규모의 철근콘크리트 주거용 초고층 건물에 대해 시공단계해석을 수행하여 각 수직부재의 부등축소량을 비교하고 콘크리트의 장기거동의 영향을 분석하였다. 이를 위해 영향요인에 따라 축소량을 탄성축소량, 크리프축소량, 건조수축축소량으로 구분하여 검토하였으며 최대 절대축소량에 대한 지배적 요인을 분석하였다. 또한, 입주완료 후 30년에서 발생한 부등축소량에 대해 사용성 검토를 진행하였으며, 구조요소에 대해 설계단계와 시공단계의 부재력을 비교하여 분석하였다.

• 전기전자학회논문지
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• 제26권3호
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• pp.488-493
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• 2022

제조 현장에 사용되는 전기적 구동 모터는 베어링의 결함 발생 시 시스템 전체의 작동 정지를 초래하게 된다. 제조 환경 작동의 정지는 시간과 금전적으로 막대한 손해를 일으키며 이러한 베어링의 결함 원인으로는 회전 요소들의 지속적인 접촉으로 인한 마모, 과도한 하중 적용, 구동 환경 등 다양한 요소가 될 수 있다. 따라서 본 논문에서는 국내 제조 환경과 유사한 모터 구동 환경을 제작하여, 다양한 원인의 베어링 환경을 모의한다. 또한 구축된 환경을 바탕으로 정상 및 결함 상태에 따라 달라지는 진동 특성의 변화를 센서를 통해 수집하여 베어링 결함 예지 정비를 위한 데이터셋을 제안한다. 진동 특성 수집에 사용된 센서는 Microphone G.R.A.S. 40PH-10을 사용하여 수집하였으며, 다양한 기계학습 모델을 사용하여 제안하는 데이터셋에 훈련된 견본 베어링 예지 정비 시스템을 제작해본 결과, 심층 신경망 모델 기준 시간 영역 92.3%, 주파수 영역 98.3%의 높은 정확도 성능을 보여준다.

• Advances in concrete construction
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• 제12권5호
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• pp.429-437
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• 2021

In the era of building engineering the intensification of Self Compacting Concrete (SCC) is world-shattering magnetism. It has lot of rewards over ordinary concrete i.e., enrichment in production, cutback in manpower, brilliant retort to load and vibration along with improved durability. In the present study, the mechanical strength of CM-2 (SCC containing 10% of rice husk ash (RHA) as cement replacement and 600 grams of glass fibers per cubic meter) was investigated at various dosages of cement replacement by fly ash (FA) and GGBS. A total of 17 SCC mixtures including two control SCC mixtures (CM-1 and CM-2) were developed for investigating fresh and hardened properties in which, ten ternary cementitious blends of SCC by blending OPC+RHA+FA, OPC+RHA+GGBS and five quaternary cementitious blends (OPC+RHA+FA+GGBS) at different replacement dosages of FA and GGBS were developed with reference to CM-2. For constant water-cement ratio (0.42) and dosage of SP (2.5%), the addition of glass fibers (600 grams/m³) in CM-1 i.e., CM-2 shows lower workability but higher mechanical strength. While fly ash based ternary blends (OPC+RHA+FA) show better workability but lower mechanical strength as FA content increases in comparison to GGBS based ternary blends (OPC+RHA+GGBS) on increasing GGBS content. The pattern for mixtures appeared to exhibit higher workablity as that of the concentration of FA+GGBS rises in quaternary blends (OPC+RHA+FA+GGBS). A decrease in compressive strength at 7-days was noticed with an increase in the percentage of FA and GGBS as cement replacement in ternary and quaternary blended mixtures with respect to CM-2. The highest 28-days compressive strength (41.92 MPa) was observed for mix QM-3 and the lowest (33.18 MPa) for mix QM-5.

• 한국지진공학회논문집
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• 제26권5호
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• pp.211-217
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• 2022

New buildings have been designed using different seismic design standards that have been revised. However, the seismic performance of existing buildings is evaluated through the same performance evaluation guidelines. Existing buildings may not satisfy the performance targets suggested in the current guidelines, but there are practical limitations to discriminating the existing buildings with poor seismic performance through a full investigation. In this regard, to classify buildings with poor seismic performance according to the applied standard, this study aimed to evaluate performance-based investigation of the seismic design proposals of buildings with different design standards. The target buildings were set as RC ordinary moment frames for office occupancy. Changes in seismic design criteria by period were analyzed, and the design spectrum changes of reinforced concrete ordinary moment resisting frames were compared to analyze the seismic load acting on the building during design. The seismic design plan was derived through structural analysis of the target model, compared the member force and cross-sectional performance, and a preliminary evaluation of the seismic performance was performed to analyze the performance level through DCR. As a result of the seismic performance analysis through the derived design, the reinforced concrete ordinary moment frame design based on AIK 2000 has an insufficient seismic performance level, so buildings built before 2005 are likely to need seismic reinforcement.

• Structural Engineering and Mechanics
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• 제85권5호
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• pp.635-644
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• 2023

The design of honeycomb sandwich structures is often challenging because these structures can be tailored from a variety of possible cores and face sheets configurations, therefore, the design of sandwich structures is characterized as a time-consuming and complex task. A data-driven computational approach that integrates the analytical method and Artificial Neural Network (ANN) is developed by the authors to rapidly predict the design of sandwich structures for a targeted maximum structural deflection. The elaborated ANN reverse design approach is applied to obtain the thickness of the sandwich core, the thickness of the laminated face sheets, and safety factors for composite sandwich structure. The required data for building ANN model were obtained using the governing equations of sandwich components in conjunction with the Monte Carlo Method. Then, the functional relationship between the input and output features was created using the neural network Backpropagation (BP) algorithm. The input variables were the dimensions of the sandwich structure, the applied load, the core density, and the maximum deflection, which was the reverse input given by the designer. The outstanding performance of reverse ANN model revealed through a low value of mean square error (MSE) together with the coefficient of determination (R2) close to the unity. Furthermore, the output of the model was in good agreement with the analytical solution with a maximum error 4.7%. The combination of reverse concept and ANN may provide a potentially novel approach in designing of sandwich structures. The main added value of this study is the elaboration of a reverse ANN model, which provides a low computational technique as well as savestime in the design or redesign of sandwich structures compared to analytical and finite element approaches.

• 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.

• Steel and Composite Structures
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• 제45권3호
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• pp.437-454
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• 2022

Elliptic-braced simple resisting frame as a new lateral bracing system installed in the middle bay of frame in building facades has been recently introduced. This system not only creates a problem for opening space from the architectural viewpoint but also improves the structural behavior. Despite the researches on the seismic performance of lateral bracing systems, there are few studies performed on the effect of the stiffness parameters on the elastic story drift and calculation of period in simple braced steel frames. To overcome this shortcoming, in this paper, for the first time, an analytical solution is presented for calculating elastic lateral stiffness in a simple steel frame equipped with elliptic brace subjected to lateral load. In addition, for the first time, in this study, a precise formulation has been developed to evaluate the elastic stiffness variation in a steel frame equipped with a two-dimensional single-story single-span elliptic brace using strain energy and Castigliano's theorem. Thus, all the effective factors, including axial and shear loads as well as bending moments of elliptic brace could be considered. At the end of the analysis, the lateral stiffness can be calculated by an improved and innovative relation through the energy method based on the geometrical properties of the employed sections and specification of the used material. Also, an equivalent element of an elliptic brace was presented for the ease of modeling and use in linear designs. Application of the proposed relation have been verified through a variety of examples in OpenSees software. Based on the results, the error percentage between the elastic stiffness derived from the developed equations and the numerical analyses of finite element models was very low and negligible.

• 문화기술의 융합
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• 제9권1호
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• pp.711-716
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• 2023

건축물 신축공사 및 리모델링 공사의 고급화 전략으로 많은 양의 석재가 필요하며 콘크리트의 생산에 필요한 강모래 강자갈의 부족으로 많은 석산에서 골재를 채취하여야 하는 실정이다. 본 연구는 건축용 석재개발의 사례를 살펴보고 지역의 주민 의식조사를 실시하고 분석하여 주민들의 석산개발에 대한 생각을 알아보고 석산개발에 따른 황폐화의 대안으로 그 지역을 개발하여 효율적인 자원으로 재활용할 수 있는 방안을 제시하는데 기초 연구를 진행하였다. 그 결과. 지역주민들은 채석장 사용에 대하여 많은 반감을 가지고 있으므로, 거주민의 지역과는 거리가 있는 지역을 채석장으로 활용할 필요가 있으며, 기존에 황폐화된 지역은 포천 아트벨리와 같이 그 지역을 잘 연구하여 그 지역 특성에 맞는 방향으로 복원 및 개발을 추진하는 것이 바람직하다는 결론을 얻었다.