• Structural Engineering and Mechanics
• /
• 제80권6호
• /
• pp.711-726
• /
• 2021

This paper presents a multiple parameters-based recursive methodology for the reliability quantification of civil structures subjected to meteorological disasters. Recognizing the challenge associated with characterizing at a single stroke all the meteorological disasters that may hit a structure during its service life, the proposed methodology by contrast features a multiparameter recursive mechanism to describe the meteorological demand of the structure. The benefit of the arrangements is that the essentially inevitable deviation of the practically observed meteorological data from those in the existing model can be mitigated in an adaptive manner. In particular, the implications of potential climate change to the relevant reliability of civil structures are allowed for. The application of the formulated methodology of recursive reliability quantification is illustrated by first considering the reliability quantification of a linear shear frame against simulated strong wind loads. A parametric study is engaged in this application to examine the effect of some hyperparameters in the configured hierarchical model. Further, the application is extended to a nonlinear hysteretic shear frame involving some field-observed cyclone data, and the incompleteness of the relevant structural diagnosis data that may arise in reality is taken into account. Also investigated is another application scenario where the reliability of a building envelope is assessed under hailstone impacts, and the emphasis is to demonstrate the recursive incorporation of newly obtained meteorological data.

• Archives of Plastic Surgery
• /
• 제45권2호
• /
• pp.146-151
• /
• 2018

Background A persistent problem in autologous breast reconstruction in skin-sparing mastectomies is skin restoration after skin necrosis or secondary oncological resection. As a solution to facilitate reconstruction, skin banking of free-flap skin has been proposed in cases where the overlying skin envelope must be resected, as this technique spares the patient an additional donor site. Herein, we present the largest series to date in which this method was used. We investigated its safety and the possibility of skin banking for prolonged periods of time. Methods All skin-sparing mastectomies and immediate autologous breast reconstructions from December 2009 until June 2013 at our institution were analysed. Results We identified 31 patients who underwent 33 free flap reconstructions in which skin banking was performed. Our median skin banking period was 7 days, with a maximum duration of 171 days. In 22.5% of cases, the banked skin was used to reconstruct overlying skin defects, and in 9.6% of cases to reconstruct the nipple-areolar complex. Microbiological and histological investigations of the banked skin revealed neither clinical infections nor malignancies. Conclusions In situ skin banking, even for prolonged periods of time, is a safe and cost-effective method to ensure that skin defects due to necrosis or secondary oncological resection can be easily reconstructed.

• 한국항공우주학회지
• /
• 제33권4호
• /
• pp.91-99
• /
• 2005

ALQ-X ECM 포드를 KF-16D와 RF-4C 항공기에 장착하기 위한 비행적합성 인증을 수행하였다. MIL-HDBK-1763에 부합하는 외부장착 스토어 인증 절차를 계획한 후 유사성 분석, 기존 스토어 질량 및 관성모멘트 분석, 구조해석 및 시험, 지상진동시험 및 플러터해석을 수행하여 비행시험 수행에 대한 안전성을 확인하였다. ALQ-X 장착 형상을 대표하는 비행 형상으로 MIL-HDBK-1763 Test 250 비행시험을 하였다. ALQ-X 장착 전, 후의 비행특성 차이를 분석하여 조종성을 평가 하고 구조건전성과 내구성은 계측데이터를 함께 분석하여 ALQ-X가 KF-16D 및 RF-4C와 적합성이 있음을 확인하였다. 그 결과로서 ALQ-X를 기존에 인증된 ALQ-88 및 ALQ-119와 동일하게 운용할 수 있음을 인증하였다. ALQ-X 비행인증 결과로서 도입 전투기에 대한 TYPE III 비행적합성 인증, 시험데이터를 사용한 플러터 해석 프로그램을 개발, MIL-STD-1553B 데이터버스를 사용한 비행시험 데이터를 획득할 수 있는 기법과 같은 기술적 성과를 거두었다. 본 비행인증 결과는 향후 국내에서 수행할 Type III 형식의 외부장착 스토어 비행인증의 모델케이스가 될 것으로 기대한다.

• 대한토목학회논문집
• /
• 제38권6호
• /
• pp.895-906
• /
• 2018

우리나라의 어린이보호구역 개선사업은 어린이가 주로 활동하는 유치원, 초등학교 주변에서 많이 발생하고 있어 어린이 교통사고 예방책의 일환으로 추진하고 있다. 하지만 어린이보호구역내 안전시설물에 대한 필수 설치 시설물과 적정 설치 수준에 대한 연구가 부족한 바, 본 연구에서는 자료포락분석을 활용한 안전시설물 설치의 효율성을 상대적으로 평가하여 개선방안을 제시하였다. 화성시 관내 초등학교중 총 28개 어린이보호구역에 대한 시설물 현황과 사고현황 자료를 구축하였다. 기존 연구상에 효과가 입증된 주요 시설물 6개(고원식 교차로, 고원식 횡단보도, 방호울타리, 미끄럼방지시설, 과속방지턱, 단속카메라)만 투입요소로 하여 분석하였다. 분석결과 28개소 중 12개소만 효율성이 있는 것으로 나타났으며, 16개소는 효율성이 떨어지는 것으로 나타났다. 효율집단으로 구분된 어린이보호구역은 방호울타리, 미끄럼방지시설, 단속카메라 설치가 비효율집단으로 구분된 어린이보호구역보다 적게 설치한 것으로 나타났다. 방호울타리는 어린이보호구역 전체연장 중 47% 정도만 설치하여도 충분히 효율성이 있는 것으로 나타났으며, 미끄럼방지시설의 개소 수는 $km^2$당 8.7개 정도면 효율성이 있는 것으로 나타났다. 비교대상의 수가 28개소로 상대적 효율성 평가지표로 활용하는 데는 본 연구가 한계가 있으며, 향후 전국단위로 그룹화 하여 각 그룹별로 효율성 평가할 수 있을 것으로 판단된다.

• Nuclear Engineering and Technology
• /
• 제52권7호
• /
• pp.1571-1578
• /
• 2020

As a critical material in very/high-temperature gas-cooled reactors, graphite material directly affects the safety of the reactor core structures. Owing to the complex structures of graphite material in reactors, the material typically undergoes complex stress states. It is, therefore, necessary to study its mechanical properties, failure modes, and strength criteria under complex stress states so as to provide guidance for the core structure design. In this study, compressive failure tests were performed for graphite material under the condition of different confining pressures, and the effects of confining pressure on the triaxial compressive strength and Young's modulus of graphite material were studied. More specifically, graphite material based on the fracture surfaces and fracture angles, the graphite specimens were found to exhibit four types of failure modes, i.e., tension failure, shear-tension failure, tension-shear failure and shear failure, with increasing confining pressure. In addition, the Mohr strength envelope of the graphite material was obtained, and different strength criteria were compared. It showed that the parabolic Mohr-Coulomb criterion is more suitable for the strength evaluation for the graphite material.

• 대한가정학회지
• /
• 제46권4호
• /
• pp.83-96
• /
• 2008

The purpose of this study is to grasp the opinion of Korean feminine seniors on the life support appliances for their healthy ageing: medication dispenser, video phone, activity monitor and sleep monitor. The focus group interviews, asking the usability of the appliances, were answered by each 6 feminine seniors of more than 65 years, residing in Corvallis of U.S.(group I), Cheongju(group II), and Ulsan(group III) of Korea. The results are as follows. (1) The medication dispenser proved to be very useful to all the respondents. All the seniors, who take more than one medicine a day, felt it helpful that the medication dispenser makes them to take medicines at fixed time. In addition, they hoped the medicine envelope to be developed for the dispenser use by the supply side. (2) The seniors showed interest in the manner the video phone works; to work by the voice, rather than by the finger. They expressed the hope of the video phone to display the communication contents, in consideration of their weakening hearing. (3) The seniors who live alone, especially, felt intimacy to the activity monitor, thinking as if some helpers were beside them. The fact that it can send emergency calls immediately when situations happen, gave the seniors emotional safety as a patron. (4) The sleep monitor, although essential to the serious cases without moving ability, was proved less necessary to the healthy seniors. They expressed the hope of this appliance to be evolved for the use with the mattress without bed.

• Structural Engineering and Mechanics
• /
• 제41권4호
• /
• pp.495-508
• /
• 2012

The strength theory of concrete is significant to structure design and nonlinear finite element analysis of concrete structures because concrete utilized in engineering is usually subject to the action of multi-axial stress. Experimental results have revealed that lightweight aggregate (LWA) concrete exhibits plastic flow plateau under high compressive stress and most of the lightweight aggregates are crushed at this stage. For the purpose of safety, therefore, in the practical application the strength of LWA concrete at the plastic flow plateau stage should be regarded as the ultimate strength under multi-axial compressive stress state. With consideration of the strength criterion, the ultimate strength surface of LWA concrete under multi-axial stress intersects with the hydrostatic stress axis at two different points, which is completely different from that of the normal weight concrete as that the ultimate strength surface is open-ended. As a result, the strength criteria aimed at normal weight concrete do not fit LWA concrete. In the present paper, a multi-axial strength criterion for LWA concrete is proposed based on the Unified Twin-Shear Strength (UTSS) theory developed by Prof Yu (Yu et al. 1992), which takes into account the above strength characteristics of LWA under high compressive stress level. In this strength criterion model, the tensile and compressive meridians as well as the ultimate strength envelopes in deviatoric plane under different hydrostatic stress are established just in terms of a few characteristic stress states, i.e., the uniaxial tensile strength $f_t$, the uniaxial compressive strength $f_c$, and the equibiaxial compressive $f_{bc}$. The developed model was confirmed to agree well with experimental data under different stress ratios of LWA concrete.

• BMB Reports
• /
• 제55권12호
• /
• pp.615-620
• /
• 2022

The murine leukemia virus-based semi-retroviral replicating vectors (MuLV-based sRRV) had been developed to improve safety and transgene capacity for cancer gene therapy. However, despite the apparent advantages of the sRRV, improvements in the in vivo transduction efficiency are still required to deliver therapeutic genes efficiently for clinical use. In this study, we established a gibbon ape leukemia virus (GaLV) envelope-pseudotyped semi-replication-competent retrovirus vector system (spRRV) which is composed of two transcomplementing replication-defective retroviral vectors termed MuLV-Gag-Pol and GaLV-Env. We found that the spRRV shows considerable improvement in efficiencies of gene transfer and spreading in both human glioblastoma cells and pre-established human glioblastoma mouse model compared with an sRRV system. When treated with ganciclovir after intratumoral injection of each vector system into pre-established U-87 MG glioblastomas, the group of mice injected with spRRV expressing the herpes simplex virus type 1-thymidine kinase (HSV1-tk) gene showed a survival rate of 100% for more than 150 days, but all control groups of mice (HSV1-tk/PBS-treated and GFP/GCV-treated groups) died within 45 days after tumor injection. In conclusion, these findings sug-gest that intratumoral delivery of the HSV1-tk gene by the spRRV system is worthy of development in clinical trials for the treatment of malignant solid tumors.

• Geomechanics and Engineering
• /
• 제34권6호
• /
• pp.683-696
• /
• 2023

The destruction and fracture of rock masses are crucial components in engineering and there is an increasing demand for the study of the influence of rock mass heterogeneity on the safety of engineering projects. The numerical manifold method (NMM) has a unified solution format for continuous and discontinuous problems. In most NMM studies, material homogeneity has been assumed and despite this simplification, fracture mechanics remain complex and simulations are inefficient because of the complicated topology updating operations that are needed after crack propagation. These operations become computationally expensive especially in the cases of heterogeneous materials. In this study, a heterogeneous model algorithm based on stochastic theory was developed and introduced into the NMM. A new fracture algorithm was developed to simulate the rupture zone. The algorithm was validated for the examples of the four-point shear beam and semi-circular bend. Results show that the algorithm can efficiently simulate the rupture zone of heterogeneous rock masses. Heterogeneity has a powerful effect on the macroscopic failure characteristics and uniaxial compressive strength of rock masses. The peak strength of homogeneous material (with heterogeneity or standard deviation of 0) is 2.4 times that of heterogeneous material (with heterogeneity of 11.0). Moreover, the local distribution of parameter values can affect the configuration of rupture zones in rock masses. The local distribution also influences the peak value on the stress-strain curve and the residual strength. The post-peak stress-strain curve envelope from 60 random calculations can be used as an estimate of the strength of engineering rock masses.

• Current Photovoltaic Research
• /
• 제11권2호
• /
• pp.49-53
• /
• 2023

Expanding the supply of BIPV is crucial to strengthening the competitiveness of the photovoltaic industry and achieving Nationally Determined Contributions through the zero-energy building mandatory policy. BIPV is a technology that integrates into the building envelope to generate electricity and provide functions as a building material. It is suitable for domestic environments with many high-rise buildings due to the narrow land area and urbanization. To expand the supply of BIPV, economics, safety, and aesthetics must be ensured. In this study, a color BIPV module with a color PET film applied as a front material was manufactured for aesthetic and economic feasibility. The relationship between power output and transmittance according to color was analyzed. By analyzing the power output of the module and the transmittance of the film, the wavelength band (transmittance reduction band) that has the greatest effect on efficiency was analyzed regarding the color of the film. The red film showed the narrowest transmittance reduction band and the lowest degree of decrease in transmittance, making it ideal for minimizing the efficiency decrease rate compared to existing ones.