• 한국항해항만학회지
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• 제26권3호
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• pp.311-316
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• 2002

본 연구에서는 항만하역장비인 스프레더용 충격흡수기의 개발을 위해 스프링과 오일댐퍼로 구성된 세 가지 형태의 모델에 대한 동적응답을 유한요소해석에 의해 수행하였다. 또한, 세 가지 모델의 충격흡수기에서 피스톤의 제한된 행정을 정적변수로 하고 목적함수인 충격에 대한 반력이 최소가 되도록 최적설계를 수행하였다. 본 연구의 결과로는 직렬식 2자유도계 모델의 반력이 가장 작게 나타났으며 그 다음으로는 1자유도계 모델, 병렬식 2자유도계 모델의 순으로 나타났다. 스프링상수와 감쇠계수의 변화가 반력에 미치는 영향을 확인하였으며, 최적설계 결과 각 모델에 대한 반력이 최소가 되는 스프링상수와 감쇠계수를 구하였다.

• 한국소음진동공학회논문집
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• 제20권7호
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• pp.651-657
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• 2010

Previous experimental results performed by many researchers for a couple of decades in South Korea have shown that an absorbing sheet inserted in a conventional floating slab system for thermal insulation or vibration absorption may amplify the vibration of the slab system at specific frequency ranges depending on the material properties of the sheet. The amplified vibration, consequently, results in the heavy weight floor impact noise exceeding the sound level limit for an apartment house, 50 dB. In this study, the amplification mechanism is examined through numerical analysis and a new slab system is proposed to reduce the amplification and control the noise. The new slab system consists of studs connecting the base slab and upper concrete finishing yielding the dramatically increased stiffness of the slab. The numerical simulation is performed to investigate the effect of the slab system with studs on the vibration and noise control. The results show that the performance of the slab is sensitive to the number and location of studs, and the heavy weight floor impact noise can be reduced up to 6~7 dB compared to the conventional slab system at the optimal stud location.

• Structural Engineering and Mechanics
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• 제51권2호
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• pp.277-297
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• 2014

Since the isolation bearings undergo large displacements in base-isolated structures, impact with adjacent structures is inevitable. Therefore, in this investigation, the effect of impact on seismic response of isolated structures mounted on double concave friction pendulum (DCFP) bearings subjected to near field ground motions is considered. A non-linear viscoelastic model of collision is used to simulate structural pounding more accurately. 2-, 4- and 8-story base-isolated buildings adjacent to fixed-base structures are modeled and the coupled differential equations of motion related to these isolated systems are solved in the MATLAB environment using the SIMULINK toolbox. The variation of seismic responses such as base shear, displacement in the isolation system and superstructure (top floor) is computed to study the impact condition. Also, the effects of variation of system parameters: isolation period, superstructure period, size of seismic gap between two structures, radius of curvature of the sliding surface and friction coefficient of isolator are contemplated in this study. It is concluded that the normalized base shear, bearing and top floor displacement increase due to impact with adjacent structure. When the distance between two structures decreases, the base shear and displacement increase comparing to no impact condition. Besides, the increase in friction coefficient difference also causes the normalized base shear and displacement in isolation system and superstructure increase in comparison with bi-linear hysteretic behavior of base isolation system. Totally, the comparison of results indicates that the changes in values of friction coefficient have more significant effects on 2-story building than 4- and 8-story buildings.

• 문화기술의 융합
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• 제6권2호
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• pp.461-466
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• 2020

본 연구는 도시철도 콘크리트궤도에 적용된 침목플로팅궤도와 목침목 분기기 궤도의 궤도지지강성과 궤도충격계수의 상관관계분석을 위해 운행선 현장측정을 수행하여 분기기 궤도의 위치별 궤도지지강성과 궤도충격계수를 측정하였다. 본선의 일반 궤도구조인 침목플로팅궤도의 궤도지지강성은 침목방진패드의 스프링강성에 지배적인 영향을 받는 것으로 분석되었다. 일반궤도와 분기기 위치별 궤도지지강성의 차이는 궤도충격계수에 직접적인 영향을 미치는 것으로 분석되었다. 연구결과, 침목플로팅 궤도구조와 분기기 궤도구조의 궤도지지강성과 궤도충격계수는 위치별로 큰 차이를 나타내는 것으로 나타났다. 따라서 본선 일반구간과 분기기 궤도의 궤도지지강성의 편차를 최소화 하여 궤도충격을 저감시키는 방안이 필요한 것으로 분석되었다.

• 복합신소재구조학회 논문집
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• 제4권2호
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• pp.25-30
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• 2013

In this study a hybrid safety barrier system consisting of steel rail and carbon fiber reinforced polymer (CFRP) post is considered. W hile CFRP post is selected for impact energy reflection due to its high strength, steel rail is selected for impact energy absorption due to its high ductility. A numerical model considering the elastoplastic behavior of steel is formulated to simulate the dynamic responses of the hybrid system subject to an impact load. A hybrid roadside guard rail system of steel rail and CFRP post is proposed and analyzed with a case study. The numerical model for the hybrid roadside guard rail system is used to find optimized design of the proposed hybrid system.

• KIEE International Transactions on Power Engineering
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• 제4A권3호
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• pp.122-128
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• 2004

With the advent of distributed generation, power systems are fundamentally impacted in regards to stability and power quality. Distributed generation has a positive impact on system restoration following a fault, higher reliability, and mitigation of effect due to voltage sag. However, distributed generation also has a negative impact on decrease of reliability such as changes of protective device setting and mal-operation. Because bulk power systems consist of various sources and loads, it becomes complicated to analyze a power system with distributed generation. The types of distributed generation are usually classified by both rotating machinery and the inverter-based system. In this paper, distributed generation is designed by rotating machinery, and the distributed system having a model of the distributed generation is simulated using EMTP. In addition, this paper presents the simulation results according to the types of distributed generation.

• 한국전자거래학회지
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• 제3권1호
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• pp.155-173
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• 1998

In this paper we present the development of internet banking and its impact on financial market. The internet banking has been introduced since 1990s, from which customers could obtain most financial services over internet, and will replace with the traditional banks. According to a survey, most of bankers agree that internet will play an important role in banking industry. The internet banking has an enormous impact on the transfer system and banking industry. The transfer system is divided into two-large-value transfer system and small-value transfer system, depending on the size of its transfer amount. The internet banking will enhance the transfer system, especially small-value transfer system. It will reduce the time lag between transaction of service and its payment. However, a congestion or a blockage in a part of network might stop the financial service all over the network, which is called "computer risk". As internet banking develops, banks have incentives to reduce their branches and have to compete with information-business companies which can offer financial EDI.

• 대한안전경영과학회지
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• 제9권5호
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• pp.49-55
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• 2007

A special cause producing temporary deviation in the underlying process can influence on process adjustment in First-Order System feedback control system. In this paper, the impact of special causes on the forecasts and the process adjustment that is based on the EWMA forecasts are derived for a first-order system. For some special causes with patterned type of contamination, the influence of the causes on the output process are explicitly investigated. A data set, contaminated by a special cause of level shift, is analyzed to confirm the impact numerically.

• 환경영향평가
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• 제14권4호
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• pp.195-202
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• 2005

The health risks from the magnetic fields exposure have been brought out difficulties in the construction of transformer substation. According to several epidemiologic studies and the relevant international organizations, magnetic fields should not exceed the exposure limits of 3mG for the people living near electric power lines. The rigid regulation of the exposure levels for the elementary school and residental areas has been established already in Switzerland and Italy. Since 1998, the environmental impact assessment system in Korea has been reviewed for power-frequency magnetic field by precautionary policies. In this study, the possible application of Prior Environmental Performance Review System for the transformer substation was reviewed from the points of the properties of the powerfrequency magnetic fields. The ranges and survey methods of the assessment for the transformer substation were proposed. The ranges of magnetic fields was between 300m to 500m for the 345kV transformer substation. It is necessary to develop further specific assessment methods for various high-voltage transformer substations.

• 대한안전경영과학회지
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• 제16권3호
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• pp.421-432
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• 2014

This study is intended to analyze the relation between G. D. Weisman's Way finding 4 elements the accessibility and efficiency of consumers as to eternal area for Seoul historical museum. The findings are summarized as the following three aspects. First, G. D. Weisman's Way finding element introduced in this study had a significant impact on visitor satisfaction.. It leads to the following conclusion: The higher the impact is, the greater accessaccessibility and efficiency are. Second, among 4 elements, the factor that had the biggest impact on the accessibility was 'visual-perceptual accessibility'. Thus, 'visual-perceptual accessibility' should be considered first to boost the accessibility to consumers. Third, among 4 elements, the factor that had the biggest impact on the efficiency was 'sign system'. Thus, 'sign system' should be considered first to boost the efficiency to consumers.