• Structural Engineering and Mechanics
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• 제40권5호
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• pp.655-663
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• 2011

Asbestos-cement is a material with valuable strength and durability. It was extensively used for water distribution pipes across the world from the 1950s until the early 1980s. The network of pipes in this case study dates from the 1970s, and after more than 30 to 40 years of service, some pipes have been found to break under common service pressure with no apparent reason. A set of mechanical tests was performed including bending, compression, pressure and crushing tests. Microscopy analysis was also used to understand the material behaviour. Tests showed that there was a clear loss of strength in the pipes and that the safety factor was under the established threshold in most of the specimens. Microscopy results showed morphological damage to the pipes. The loss of strength was attributed to a leaching effect. Leaching damages the cement matrix and reduces the frictional interfacial shear stress.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.185-191
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• 2020

Plant-specific analyses of an advanced reactor have been performed to assure the structural integrity of the reactor pressure vessel during transient conditions, which are expected to initiate pressurized thermal shock (PTS) events. The vessel failure probabilities from the probabilistic fracture mechanics analyses are combined with the transient frequencies to generate the through-wall cracking frequencies, which are compared to the acceptance criterion. Several sensitivity analyses are performed, focusing on the orientations and sizes of cracks, the copper content, and a flaw distribution model. The results show that the integrity of the reactor vessel is expected to be maintained for long-term operation beyond the design lifetime from the PTS perspective using the design data of the advanced reactor. Moreover, a fluence level exceeding 9×10¹⁹ n/㎠ is found to be acceptable, generating a sufficient margin beyond the design lifetime.

• 한국언어정보학회지:언어와정보
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• 제8권1호
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• pp.163-182
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• 2004

Since metaphor was proposed to be a matter of thought instead of language over two decades ago, the research in this area has made most of its progress by the cognitivists. For the cognitivists represented by Lakoff, metaphor is not a mere poetic or rhetoric device, but is central to our everyday language. Furthermore, according to them, we categorize the world and break it into concepts mainly through metaphors, and truth conditions simply cannot account for metaphor. However, this cognitivists' view has been severely counterattacked by the truth-conditional semanticists. Their main criticism is that the cognitivists do not provide a way to go from our internal representations to the outside world. It is also criticized that the cognitive theory of metaphor as cross-conceptual domain mappings is too broad and general, and that they do not explain why a particular metaphorical expression should be subsumed under one mapping rather than another mapping, i.e., their schemes and structural relations are not predictive. In this context, the purpose of this paper is to propose a model for metaphor interpretation that combines the virtues of the two opposite views of metaphor. Truth-conditional semantics cannot ignore cognitive aspects of language, so-called states of affairs or mental representations, while cognitive theories cannot neglect vigorous representation of meaning with objective reality. This paper will try to present a preliminary outline of this combining model.

• 품질경영학회지
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• 제49권3호
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• pp.255-268
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• 2021

Purpose: We sought to understand why a high-speed rotating projectile featuring a fuze-and-body assembly sometimes exhibited airburst, and we intended to improve the flight stability by eliminating airburst. Methods: We performed characteristic factor analysis, structural mechanics modeling, and dynamic modeling and simulation; and we scheduled firing tests to discover the cause of airburst. We used a step-by-step procedure to analyze the reliability function for selecting the bonding force standard that prevents airburst. Results: The 00MM high-speed rotating projectile features a fuze bonded to a body assembly; the bonding sometimes can break on firing. The resulting contact force, vibration and roll damping during flight generated yaw. Flight became unstable; fuze operation triggered an airburst. Our reliability test improved the bonding force standard (the force was increased). When the bonding force was at least the minimum required, a firing test revealed that airburst/flight instability disappeared. Conclusion: Analysis and identification of the causes of flight instability and airburst render military training safer and enhance combat power. Ammunition must perform as designed. Our method can be used to set standards that improve the performances of similar types of ammunition.

• Structural Engineering and Mechanics
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• 제68권5호
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• pp.537-547
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• 2018

This research presents the effect of anisotropy of the hollow disc mode under Brazilian test using PFC3D. The Brazilian tensile strength test was performed on the hollow disc specimens containing the bedding layers and then these specimens were numerically modeled by using the two dimensional discrete element code (PFC3D) to calibrate this computer code for the simulation of the cracks propagation and cracks coalescence in the anisotropic bedded rocks. The thickness of each layer within the specimens varied as 5 mm, 10 mm and 20 mm and the layers angles were changed as $0^{\circ}$, $25^{\circ}$, $50^{\circ}$, $75^{\circ}$ and $90^{\circ}$. The diameter of internal hole was taken as 15 mm and the loading rate during the testing process kept as 0.016 mm/s. It has been shown that for layers angles below $25^{\circ}$ the tensile cracks produce in between the layers and extend toward the model boundary till interact and break the specimen. The failure process of the specimen may enhance as the layer angle increases so that the Brazilian tensile strength reaches to its minimum value when the bedding layers is between $50^{\circ}$ and $75^{\circ}$ but its value reaches to maximum at a layer angle of $90^{\circ}$. The number of tensile cracks decreases as the layers thickness increases and with increasing the layers angle, less layer mobilize in the failure process.

• The Journal of Asian Finance, Economics and Business
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• 제8권7호
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• pp.1-9
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• 2021

This paper investigates the impact of the domestic and global outbreak of the coronavirus (COVID-19) pandemic on the trading size of the Malaysian stock (MS) market. The theoretical model posits that stock markets are affected by their response to disasters and events that arise in the international or local environments, as well as to several financial factors such as stock volatility and spread bid-ask prices. Using daily time-series data from 27 January to 12 May 2020, this paper utilizes the traditional Augmented Dickey and Fuller (ADF) technique and Zivot and Andrews with structural break' procedures for a stationarity test analysis, while the autoregressive distributed lag (ARDL) method is applied according to the trading size of the MS market model. The analysis considered almost all 789 listed companies investing in the main stock market of Malaysia. The results confirmed our hypotheses that both the daily growth in the active domestic and global cases of coronavirus (COVID-19) has significant negative effects on the daily trading size of the stock market in Malaysia. Although the COVID-19 has a negative effect on the Malaysian stock market, the findings of this study suggest that the COVID-19 pandemic may have an asymmetric effect on the market.

• 한국컴퓨터정보학회논문지
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• 제26권8호
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• pp.157-164
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• 2021

회귀분석은 반응변수와 예측변수들 간의 관련성을 설명하기 위해 사용되는 잘 알려진 통계 테크닉이다. 특히 연구자들은 두 개의 독립 모집단에서의 모형들의 회귀계수들(절편과 기울기)을 비교하는데 관심이 있다. Gregory Chow에 의해 제안된 Chow 검정은 회귀모형들을 비교하고 선형회귀모형 안에 구조적 브레이크가 존재하는지를 검정하기 위해 보통 사용되는 방법들 중의 하나이다. 본 연구에서는 두 독립 선형회귀모형들의 등가성을 검정하기 위해 퍼뮤테이션 방법을 제안하고 Chow 검정과 비교한다. 그리고 퍼뮤테이션 검정과 Chow 검정의 검정력을 조사하기 위해 시물레이션 연구를 진행하였다.

• The Journal of Asian Finance, Economics and Business
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• 제8권9호
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• pp.1-9
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• 2021

This study aimed to investigate the existence of the Feldstein-Horioka (1980) puzzle in international macroeconomics by applying the conditional Autoregressive Distributed Lag (ARDL) model to examine the long-run relationship between national savings and investments in Thailand and China. The input of this study relied on annual national savings and investments as a fraction of GDP during 1980-2019 which was collected from China National Bureau of Statistics (NBS) and Thailand National Economic and Social Development Council (NESDC). Hypothetically, Augmented Dickey-Fuller (ADF) and Phillips-Perron (PP) unit root tests were applied to test the stationary properties and to investigate the integration level of selected time series. The empirical results, confirmed by cumulative sum (CUSUM) and cumulative sum square (CUSUMSQ), maintained no serial correlation and structural break problems. The finding of this study suggested that the Feldstein-Horioka puzzle in Thailand did not exist significantly. Thailand's national savings and investments nexus was independent, following the classic economic idea that financial liberalization, or perfect capital mobility, allowed national savings and investments to flow freely to countries with better interest rates. Whereas, a strong significant correlation was found in the case of China during the fixed exchange rate regime switching in 1994 and post WTO participation after 2001-2019.

• Structural Engineering and Mechanics
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• 제84권2호
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• pp.167-180
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• 2022

A strategic structure when exposed to direct hit of conventional bomb/projectile are severely damaged because of large amounts of energy released by the impact and penetration of bomb. When massive concrete slabs suffer a direct hit, the energy released during impact and penetration process are able to easily break up large mass of concrete. When over stressed under such impact of bombs, the concrete structure fails showing brittle behavioural nature. This paper is intended to study and suggest the protective measures for structures used for strategic application by adopting a means to dissipate the large quantum of energy released. To quantitatively evaluate the force, displacement and energy in such scenario, a fine numerical model of the proposed layered structure of different combinations was built in ANSYS programme in which tri-nitrotoluene (TNT) explosive was detonated at penetration depth calculated for GP1000 Lbs bomb. The distinct blast mitigation effect of the proposed structure was demonstrated by adopting various layers/barriers created as protective measures for the strategic structure. The calculated result shows that the blast effect on the structure is potentially reduced due to provision of buster slab with sand cushioning provided as protective measure to the main structure. This concept of layered protective measures may be adopted for safeguarding strategic structures such as Domes, Tunnels and Underground Structures.

• 보존과학회지
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• 제33권1호
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• pp.25-33
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• 2017

보은 법주사 사천왕석등의 주부재는 K-장석이 반상조직을 보이는 티탄철석계열의 흑운모 화강섬록암 석재이며, 땅 속에 묻혀있던 알칼리 화강암 재질의 하대하석 및 지대석이 복원되며 본래의 모습을 되찾았다. 석등에는 균열 및 탈락에 의한 손상이 두드러지게 발생하였으며 이외에도 변색, 염 침착 및 생물 착생 등이 관찰된다. 특히 화사석의 전면과 후면을 관통하는 균열과 수평 불균형으로 인해 물리 및 구조적 안정성이 취약한 상태이다. 이에 따라 티타늄 보강재의 위치, 규격 및 정착 길이를 산정하여 구조적 보강을 실시하였다. 화학 및 생물학적 오염물은 석재에 손상을 주지 않는 한도 내에서 세정하고 산화된 철편을 티타늄제로 교체하였다. 또한 에틸 실리케이트계 강화제를 도포하여 암석의 강화와 원활한 수분 배출을 유도하였다.