• Geomechanics and Engineering
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• 재33권6호
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• pp.597-609
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• 2023

The instability and failure of engineered rock masses are influenced by crack initiation and propagation. Uniaxial compression and acoustic emission (AE) experiments were conducted on cracked sandstone. The effect of the crack's dip on the crack initiation was investigated using fracture mechanics. The crack propagation was investigated based on stress-strain curves, AE multi-parameter characteristics, and failure modes. The results show that the crack initiation occurs at the tip of the pre-fabricated crack, and the crack initiation angle increases from 0° to 70° as the dip angle increases from 0° to 90°. The fracture strength k_cr is derived varies in a U-shaped pattern as β increased, and the superior crack angle β_m is between 36.2 and 36.6 and is influenced by the properties of the rock and the crack surface. Low-strength, large-scale tensile cracks form during the crack initiation in the cracked sandstone, corresponding to the start of the AE energy, the first decrease in the b-value, and a low r-value. When macroscopic surface cracks form in the cracked sandstone, high-strength, large-scale shear cracks form, resulting in a rapid increase in the AE energy, a second decrease in the b-value and an abrupt increase in the r-value. This research has significant theoretical implications for rock failure mechanisms and establishment of damage indicators in underground engineering.

• 한국기계연구소 소보
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• 통권17호
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• pp.61-68
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• 1987

The main objective of this paper is to develop the computer-aided vibrational signal processing and monitoring system of rotating machinery. This system has an automatic data acquisition capability and analyze for machine fault diagnosis. By spectrum analysis, machine’s failure can be identified. The monitoring system enables diagnosis of the fault in rotating machinery. In this study, the conventional electrical fans are selected as a model case. The date processing and fault monitoring system proposed here can be applied to the automation of the inspection process in assembling motor-shaft systems. The automatic inspection can enhance the product quality and keep it stable. Since the proposed system is developed for personal computers, it might be cheap in cost and easy in installation.

• 플랜트 저널
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• 제6권3호
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• pp.46-52
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• 2010

This study investigated the coating failure of the blades of booster fans for the 200 MW flue gas desulfurization plant. Although the arc sprayed SM8222 have been tried as blade coating materials aimed to apply as alternatives of Metcoloy(R)2 due to better corrosion-erosion resistance but it is failed. Bond strength tests and practical field experiences have demonstrated high velocity oxy-fuel(HVOF) coating method with Diamalloy 3004 as an alternative to Metcoloy(R) 2 arc spray.

• 한국안전학회지
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• 제27권6호
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• pp.54-58
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• 2012

This paper is purposed to analyze electric leakage component which can prevent electrical fires on breaker capacity expansion and power failure by operation of ELB(Earth leakage breaker) for stable sizes. In order to analysis for electric leakage component for stable sizes, this paper studied field state investigation which are at stable companies( 10 companies) in cheong-won location to deduce the problems of electric leakage component is analyzed. The field state experiment method is measured with electric leakage component which load part of ELB detected by electric loads(electrical fan, lighting, auto waterer, feeder and halogen lighting) and stable sizes. Results show that electric leakage component suggested in this paper are valuable and usable to electrical fire in leakage current based on environment factor, which will prevent severe damage to human beings and properties and reduce the electrical fires in stable.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2069-2087
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• 2023

In nuclear power plant (NPP) accidents, the containment is subject to high temperatures and high internal pressures, which may further trigger serious chain accidents such as core meltdown and hydrogen explosion, resulting in a significantly higher accident level. Therefore, studying the mechanical performance of a containment under high temperature and high internal pressure is relevant to the safety of NPPs. Based on similarity principles, the 1:3.2 scale model of a prestressed concrete containment vessel (PCCV) of a NPP was designed. The loading method, which considers the thermal-pressure coupling conditions, was used. The mechanical response of the PCCV was investigated with a simultaneous increase in internal pressure and temperature, and the failure mechanism of the PCCV under thermal-pressure coupling conditions was revealed.

• 한국포장학회지
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• 제28권2호
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• pp.143-149
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• 2022

PCS needs to freely switch AC and DC to connect the battery, external AC loads and renewable energy in both directions for energy efficiency. Whenever converting happens, power loss inevitably occurs. Minimization of the power loss to save electricity and convert it for usage is a very critical function in PCS. PCS plays an important role in the ESS(Energy Storage System) but the importance of stabilizing semiconductors on PCB(Printed Circuit Board) should be empathized with a risk of failure such as a fire explosion. In this study, the temperature variation inside PCS was reviewed by cooling fan on top of PCS, and the vibration characteristics of PCS were analyzed during truck transportation for reliability of the product. In most cases, a cooling fan is mounted to control the inner temperature at the upper part of the PCS and components generating the heat placed on the internal aluminum cooling plate to apply the primary cooling and the secondary cooling system with inlet fans for the external air. Results of CFD showed slightly lack of circulating capacity but simulated temperatures were durable for components. The resonance points of PCS were various due to the complexity of components. Although they were less than 40 Hz which mostly occurs breakage, it was analyzed that the vibration displacement in the resonance frequency band was very insufficient. As a result of random-vibration simulation, the lower part was analyzed as the stress-concentrated point but no breakage was shown. The steel sheet could be stable for now, but for long-term domestic transportation, structural coupling may occur due to accumulation of fatigue strength. After the test completed, output voltage of the product had lost so that extra packaging such as bubble wrap should be considered.

• 한국엔터테인먼트산업학회논문지
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• 제14권2호
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• pp.1-14
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• 2020

본 연구는 싸이 이후 더 확대된 K-Pop 시장에서 BTS의 선호요인이 특징적으로 무엇인지를 밝혀보고자 하는 관심에서 시작되었다. 본 연구의 목적을 위해 국내를 비롯해 BTS가 인기를 끌고 있는 대만, 태국, 베트남을 대상으로 설문조사를 시행하였다. 본 연구의 결과를 살펴보면 BTS 선호요인 전체에 대해 베트남과 태국이 가장 긍정적인 인식을 하는 것으로 나타났고, 가장 높은 정(+)의 영향을 미치는 요인은 BTS의 차별적 감각으로 분석되었다. 본 연구가 동남아와 한국 팬들을 대상으로 하여 폭넓은 설문조사 대상자를 통한 확대된 연구이며, BTS 선호요인에 대한 새로운 시각에서의 규명이 가능했다는 의의에도 불구하고, 팬덤효과와 구매의도에 영향을 미칠 수 있는 다양한 변수를 고려하지 못하고, 세계적으로 더 많은 팬을 확보하고 있는 미국, 유럽 지역 팬들에 대한 의식조사를 함께하지 못한 점이 본 연구의 한계가 될 수 있을 것이다.

• Structural Engineering and Mechanics
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• 제14권3호
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• pp.331-343
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• 2002

Because of the increasing span of arch bridges, ultimate capacity analysis recently becomes more focused both on design and construction. This paper investigates the static and ultimate behavior of a long-span steel arch bridge up to failure and evaluates the overall safety of the bridge. The example bridge is a long-span steel arch bridge with a 550 m-long central span under construction in Shanghai, China. This will be the longest central span of any arch bridge in the world. Ultimate behavior of the example bridge is investigated using three methods. Comparisons of the accuracy and reliability of the three methods are given. The effects of material nonlinearity of individual bridge element and distribution pattern of live load and initial lateral deflection of main arch ribs as well as yield stresses of material and changes of temperature on the ultimate load-carrying capacity of the bridge have been studied. The results show that the distribution pattern of live load and yield stresses of material have important effects on bridge behavior. The critical load analyses based on the linear buckling method and geometrically nonlinear buckling method considerably overestimate the load-carrying capacity of the bridge. The ultimate load-carrying capacity analysis and overall safety evaluation of a long-span steel arch bridge should be based on the geometrically and materially nonlinear buckling method. Finally, the in-plane failure mechanism of long-span steel arch bridges is explained by tracing the spread of plastic zones.

• Steel and Composite Structures
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• 제23권2호
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• pp.187-194
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• 2017

To reuse a broken plain concrete (PC) arch, a retrofitting method was proposed to ensure excellent structural performances, in which carbon fiber reinforced polymers (CFRPs) were applied to repair and strengthen the damaged PC arch through bonding and wrapping techniques. Experiments were carried out to reveal the deformation and the load carrying capacity of the retrofitted composite arch. Based on the experiments, repairing and strengthening effects of the CFRP retrofitted broken arch were revealed. Simplified analysing model was suggested to predict the peak load of the CFRP retrofitted broken arch. According to the research, it is confirmed that absolutely broken PC arch can be completely repaired and reinforced, and even behaves more excellent than the intact PC arch when bonded together and strengthened with CFRP sheets. Using CFRP bonding/wrapping technique a novel efficient composite PC arch structure can be constructed, the comparison between rebar reinforced concrete (RC) arch and composite PC arch reveals that CFRP reinforcements can replace the function of steel bars in concrete arch.

• 디지털융복합연구
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• 제17권10호
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• pp.417-426
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• 2019

본 논문의 연구 목적은 게임 원작으로 만든 영화의 흥행 환경을 비교하여 게임 원작으로 만든 영화의 흥행 성공과 실패를 분석하고 좋은 게임원작 영화를 만드는 데 필요한 요소를 도출해내는 것이라고 할 수 있다. 구체적인 분석 콘텐츠는 <워크래프트: 전쟁의 서막>, <앵그리버드>, <툼레이더>로 게임을 리메이크한 영화의 구체적인 성공과 실패 요소에 대해 연구하였다. 연구를 통해 분석된 내용으로는, 관객층은 게임 팬층과 비게임 팬층으로 나누어 질 수 있고, 영화를 만들 때 양쪽에 대한 기대심리를 어떻게 반영하느냐가 영화를 만드는 중요한 요소라는 것이다. 또한 다른 주제관과 다른 스타일과 장르의 게임을 영화로 리메이크시 천편일률적인 동일한 방식으로 만들 수는 없고 융통성 있는 다양성과 매니지먼트가 필요하다. 무조건적인 게임의 시나리오 화나 영화의 게임전환은 대중에게 인기를 얻을 수 없으며 구체적인 타겟 대상 관중에 대한 분석이 매우 중요하다고 할 수 있다.