• Steel and Composite Structures
• /
• v.22 no.5
• /
• pp.1115-1140
• /
• 2016

This paper proposes an extension of the Improved Forced Based Design procedure to 3D steel structures. The Improved Forced Based Design (IFBD) procedure consists of a more rational sequence of the design checks proposed in Eurocode 8 and involves a more realistic selection of the behaviour factor instead of selecting an empirical value based on the ductility class and lateral resisting system adopted. The design procedure was tested on a group of four 3D steel structures, composed by moment-resisting frames with three storeys height and the same plan configuration in all storeys. The plan configuration was defined in order to target lateral restrained or unrestrained systems as well as plan regular or irregular structures. The same group of structures was also designed according to the force-based process prescribed in Eurocode 8. The member sizes obtained through the two approaches were compared and the seismic performance was assessed through nonlinear static and time-history analyses. The limit states referred to structural and non-structural damage, considering the two levels design approach, which are the serviceability and the ultimate limit states, were examined. The results obtained reveal that the IFBD leads to more economical structures that still comply with the performance requirements prescribed in Eurocode 8.

• Steel and Composite Structures
• /
• v.23 no.2
• /
• pp.153-160
• /
• 2017

It is extremely important to be aware of the ballistic performances of engineering materials in order to be able to choose the lightest armor providing full ballistic protection in civil and military applications. Therefore, ballistic tests are an important part of armor design process. In this study, ballistic performance of plates made of carbon steel and cold worked tool steel against 7.62 mm AP (armor-piercing) bullets was examined experimentally and numerically in accordance with NIJ standards. Samples in different sizes were prepared to demonstrate the effect of target thickness on ballistic performance. Some of these samples were coated with titanium nitride using physical vapor deposition (PVD) method. After examining all successful and unsuccessful samples at macro and micro levels, factors affecting ballistic performance were determined. Explicit non-linear analyses were made using Ls-Dyna software in order to confirm physical ballistic test results. It was observed that the ballistic features of steel plates used in simulations comply with actual physical test results.

• Composites Research
• /
• v.17 no.5
• /
• pp.68-77
• /
• 2004

The electromagnetic (EM) absorption or shielding characteristics of a material is an important issue not only for military purpose but also for commercial purposes such as radar, electric or telecommunication devices. In order to design the effective electromagnetic wave absorber, the electromagnetic characteristics of the constituents of the material should be available in target frequency band. Also, it must be possible to predict the electromagnetic properties of absorbers with respect to the content of lossy ingredients. In this study, the dielectric properties of unsaturated polyester resins containing nano-size conductive carbon black powder were measured with a free space method in the X-band frequency range and analyzed with respect to the content of carbon black. Finally, the method for estimating the dielectric properties of polymeric resin containing conductive carbon black with respect to the EM frequency was developed and verified.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.05a
• /
• pp.183-184
• /
• 2015

Recent structural approach of the House of Commons has been an increase in demand for dry wall light due to a change in load bearing composite structure of a flat plate type structure under the name of long-life housing, attach the attachment to the wall as the needs of the residents of reserved space increases things that are on the rise. However, depending on the strength of collapse accidents is shown wall and recent wall deposits are required, a load resistance evaluation method of the deposit of the need is the situation. Therefore, in this study, for the evaluation of the evaluation of dry lightweight wall as widely used gypsum board and ALC lightweight wall of two types of laboratory the wall through the previous studies to be installed in direct co-housing to the target and field experiments I want to evaluate the different points.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1993.05a
• /
• pp.64-65
• /
• 1993

MPB 조성영역인 Zr/Ti=52/48의 composite ceramic target을 사용하여 RF magnetron sputtering 방법으로 기판온도 약 30$0^{\circ}C$에서 RZT 박막을 Pt/Ti/Si 기판위에 증착시켰다. 안정상인 perovskite 구조를 형성시키기 위하여 PbO분위기에서 furnace annealing 과 Repid thermal annealing을 실시하여 열처리 방법에 따른 상형성 및 계면반응과 그에 따른 전기적 특성을 고찰 하였다. Pt 의 두께가 250$\AA$인 경우 furnace annealing 시 $650^{\circ}C$에서 perouskite 상이 형성되었으나 Pt층이 산소의 확산을 방지하지 못하여 상부의 Ti 층이 TiOx로 변태하였으며 하부의 Ti는 Si 과 반응하여 Ti-silicide 롤 변태하였다. 또한 75$0^{\circ}C$,60sec 인 경우 Pt 층의 응집화가 관찰되어 하부전극으로서 적용이 적절하지 못하다. 급속열처리를 실시한 경우에도 마찬가지로 Ti 층이 TiOx 와 silicide 층으로 변태되었다. Pt의 두께가 1000$\AA$인 경우에도 250$\AA$와는 달리 RTA 시 (III)방향으로 Furace annealing 시(001)방향으로 우선 성장하였다. 이는 Ti(001), P(111),PZT(111)면의 lattic mismatch 가 매우 작은데다 RTA 시 계면반응이 거의발생하지 않아 PZT 박막이 (111) 방향으로 우선 성장한 것으로 보인다. Furnace annealing 경우는 심한 계면반응이 발생하여 Pt층에 어느 정도 영향을 주었기 때문에 우선성장 방향이 바뀌었다구 생각한다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.235-235
• /
• 2010

장비와 cutting기술의 발전으로, 높은 효율성을 지닌 어려운 작업 재료들의 고속 건조 가공기술은 생산성, 가격 인하 그리고 환경적인 관점에서 중요성이 증가하게 되었다. AlTiN에서 Si의 첨가는 40GPa이상의 고경도와 1000도 이상의 산화온도를 지닌 나노혼합물 코팅을 형성시키는 것으로 알려졌다. 또한 Si가 아닌 다른 soft 물질을 첨가하고 3성분 이상의 다성분계 박막을 형성하는 실험을 하여, 물성이 어떻게 달라지는지 확인하였다. 특히, 나노 코팅층 형성이 매우 어려운 Al-Ti-N 합금계에서 Si, Cu 첨가의 영향 및 이러한 코팅층 형성을 단일합금을 이용하여 행하였을 때, 장점을 확인하였다. 이러한 연구를 위하여 Ti-Al의 합금 조성을 경도가 가장 우수한 것으로 알려진 50 : 50으로 하여 타겟을 만들고 증착시켜 기초실험을 진행하여 물성조건을 확인하고 이에 근거하여 실험을 진행하였다. 또한 3 원계 합금으로서 Cu, Si를 첨가한 연구를 수행하였다. 또한, 최적 조성의 합금 조성을 확인한 후, 단일 합금 타겟을 제조하였으며 이를 이용하여 형성된 코팅층과 다성분계 타겟을 이용한 박막의 물성을 비교하였다. 증착된 박막의 분석장비로는 SEM, EDS, XRD 와 AFM등을 이용하였으며, 막의 조직과 증착 두께, 조도 그리고 경도를 확인하고 막의 물성 특성이 향상됨을 입증하였다.

• Journal of Welding and Joining
• /
• v.28 no.5
• /
• pp.86-92
• /
• 2010

In GMAW processes, bead geometry is a criterion to estimate welding quality. Bead geometry is affected by welding current, arc voltage, welding speed, shielding gas and so on. Thus the welding condition has to be selected carefully. In this paper, an experimental method for the selection of optimal welding condition was proposed in the root pass welding which was done along the GMA V-grooved butt weld joint. This method uses the response surface analysis in which the width and height of back bead were chosen as the quality variables of the weld. The overall desirability function, which is the combined desirability function for the two quality variables, was used as the objective function for getting the optimal welding condition. Through the experiments, the target values of the back bead width and the height were chosen as 4mm and 1mm respectively for the V-grooved butt weld joint. From a series of welding test, it was revealed that a uniform weld bead can be obtained by adopting the optimal welding condition which was determined according to the method proposed.

• Smart Structures and Systems
• /
• v.15 no.1
• /
• pp.41-55
• /
• 2015

This study proposes a laser based impedance measurement system and impedance based pipe corrosion and bolt-loosening monitoring techniques under temperature variations. For impedance measurement, the laser based impedance measurement system is optimized and adopted in this paper. First, a modulated laser beam is radiated to a photodiode, converting the laser beam into an electric signal. Then, the electric signal is applied to a MFC transducer attached on a target structure for ultrasonic excitation. The corresponding impedance signals are measured, re-converted into a laser beam, and radiated back to the other photodiode located in a data interrogator. The transmitted impedance signals are treated with an outlier analysis using generalized extreme value (GEV) statistics to reliably signal off structural damage. Validation of the proposed technique is carried out to detect corrosion and bolt-loosening in lab-scale carbon steel elbow pipes under varying temperatures. It has been demonstrated that the proposed technique has a potential to be used for structural health monitoring (SHM) of pipe structures.

• The Journal of Industrial Distribution & Business
• /
• v.12 no.8
• /
• pp.41-52
• /
• 2021

Purpose: The study aims to analyze effects of wage on FDI inflows based on the threshold of institutional quality in 14 developing economies of Southeast and South Asia over the period from 2000-2017. Research design, data, and methodology: The study applies a fixed effect panel threshold regression. As a proxy for the institutional quality, it uses the six components of Worldwide Governance Indicators or a compound index obtained by an average of the six components. The data were taken from World Bank, the Chinn & Ito Database, and UNCTAD. To the best of our knowledge, no researches so far have considered the threshold of institutional quality in estimating the effect of wage on FDI inflows. Results: The composite index and each component of the six indicators of institutional quality except for voice and accountability, and regulatory quality are found to have nonlinear effects on FDI inflows. When the institutional quality is below the threshold, wage affects FDI inflows negatively. When the institutional quality is above the threshold, however, wage does not significantly affect FDI inflows. Conclusions: The effect of wage on FDI inflows varies depending on whether the institutional quality of the target countries is above or below the threshold.

• The Journal of Industrial Distribution & Business
• /
• v.12 no.10
• /
• pp.31-41
• /
• 2021

Purpose: This study estimates the threshold values of institutional quality through investigating the non-linear effect of six sub-indices of Worldwide Governance Indicators on FDI inflows in 34 developing countries in Asia and Eastern Europe over the period from 2000-2017. Research Design, data and methodology: GMM EGLS is employed which does not include the lagged value of the dependent variable as an independent variable. As a proxy for the institutional quality, either one of the six sub-indices of WGI from World Bank or the composite index obtained through a principal component analysis is used in a separate model. Results: An improvement in institutional quality, when the quality stays below a certain threshold level, does not increase FDI inflows, and only when the quality is above the threshold, it can positively influence FDI inflows. The threshold values of political stability and absence of violence, government effectiveness, and rule of law are relatively higher than those of the other dimensions of WGI. Conclusion: Institutional quality of the developing economies of Asia and Eastern Europe has a non-linear effect on FDI inflows. The target countries need to upgrade their institutional quality above the threshold in order to attract more FDIs.