• 대한조선학회 특별논문집
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• 대한조선학회 2015년도 특별논문집
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• pp.69-73
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• 2015

An evaluation of the accidental limit state (ALS) for design of a semi-submersible drilling rig is one of the essential design requirements as well as ultimate limit state (ULS) and fatigue limit state (FLS). This paper describes the ALS evaluation on the explosion accident at shale shaker room of semi-submersible drilling rig. There are three steps for the ALS evaluation such as structural analysis at concept design, risk based safety design and structural analysis at detailed design. For the ALS evaluation at concept design, conceptual explosion overpressure from the Rule guided by the classification society was used in the structural analysis that was carried out using LS-DYNA. To set up the design accidental load (DAL), explosion analysis was carried out using FLACS taking safety barriers into consideration. Then, the structural analysis was carried out applying DAL for the ALS evaluation at detailed design. Through the ALS evaluation on the explosion at shale shaker room, the importance of the risk based safety design was described.

• 한국해양공학회지
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• 제32권6호
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• pp.411-418
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• 2018

This paper introduces a new method of ice load generation in the time domain for the station-keeping performance evaluation of Arctic offshore structures. This method is based on the ice load spectrum and mean ice load. Recently, there has been increasing interest in Arctic offshore technology for the exploration and exploitation of the Arctic region because of the better accessibility to the Arctic ocean provided by the global warming effect. It is essential to consider the ice load during the development of an Arctic offshore structure. In particular, when designing a station-keeping system for an Arctic offshore structure, a consideration of the ice load acting on the vessel in the time domain is essential to ensure its safety and security. Several methods have been developed to consider the ice load in the time domain. However, most of the developed methods are computationally heavy because they consider every ice floe in the sea ice field to calculate the ice load acting on the vessel. In this study, a new approach to generate the ice load in the time domain with computational efficiency was suggested, and its feasibility was examined. The ice load spectrum and mean ice load were acquired from a numerical analysis with GPU-event mechanics (GEM) software, and the ice load with the varying heading of a vessel was reconstructed to show the feasibility of the proposed method.

• Nuclear Engineering and Technology
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• 제24권2호
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• pp.183-192
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• 1992

한국 표준 원전의 부하추종운전 능력 향상을 위하여 노심 축 방향 출력분포 제어에 기존의 regulating bank와는 별개의 heavy bank를 사용하는 노심 제어 기법인 Mode K를 제시하였다 이 경우 heavy bank는 제어할 수 있는 축방향 출력 변화의 범위가 크며, 또한 bank의 움직임과 축 방향 출력 변화가 단조적 관계를 항상 유지할 수 있으므로 운전을 용이하게 할 뿐 아니라 자동제어가 가능하도록 한다. Mode K기법을 이용한 노심 제어 자동화는 부하추종운전에 대한 운전원의 부담을 경감시킬 수 있으며, 특히 주파수 제어 운전등 미리 예측되지 않은 부하변동에 응동할 수 있는 능력을 갖게 한다. 표준 원전의 참조 발전소인 영광 3,4호기의 운전을 모의 계산함으로써 Mode K 의 설계 개념을 평가하였는데 그 결과를 통하여 한국 표준 원전의 실제적 부하추종운전을 위하여 Mode K 기법을 적절하게 사용할 수 있음을 입증하였다.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.2242-2248
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• 2015

본 연구는 폭설로 인하여 비닐하우스가 붕괴되는 사고가 잇따르는 것에 대비하여 효율적인 비닐하우스 골조의 개선방안을 찾고자 진행되었다. 2013년 겨울, 비닐하우스 피해가 가장 컸던 곳은 경북과 강원도로, 이 지역에서 가장 많이 사용되고 있는 비닐하우스 유형(07-단동 3형, 07-단동 18형)에 대하여 최대 적설량 대비 30%까지 하중을 증가시켜 MIDAS GEN 프로그램을 사용하여 구조적 안전성을 검토하였다. 해석의 결과, 경주의 비닐하우스는 적설하중의 중가에 대해 안전하였으나 속초의 경우는 위험요인이 발생하였으며, 강릉의 비닐하우스는 기존 적설하중에서도 붕괴 가능성이 있는 것으로 나타났다. 폭설에 대비, 비닐하우스 구조단면의 성능을 개선하기 위하여 서까래를 이루는 원형파이프 단면의 성능을 개선하는 동시에 서까래의 간격을 증가시켜 적정 비닐하우스 구조를 검토한 결과, 서까래의 관경과 간격을 증가시키는 방안이 서까래의 두께와 간격을 증가시키는 방안보다 구조적으로 효율적인 것으로 해석되었다. 향후 폭설에 대비하여 비닐하우스의 서까래 관경을 증가시킨 적정 규격의 제안이 필요할 것으로 판단된다.

• 한국정보과학회논문지:정보통신
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• 제29권5호
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• pp.466-472
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• 2002

본 논문에서는 계층적 셀 구조에서 umbrella 셀과 overlaid 셀 사이의 부하 분배 문제를 연구한다. 부하 분배 정책을 제안하고 HSDPA에서 인터넷 트래픽을 전달하는 경우를 시뮬레이션하여 제안된 정책의 성능을 평가한다. 평가 결과, 마이크로 셀이 피코 셀의 부하를 잘 분담해주는 것으로 나타났으며, 특히 특정한 피코 셀 집단에 큰 부하가 가해졌을 경우에 그 효과가 크게 나타났다. 이 정책을 사용할 경우, 비정상적인 큰 부하에 대처하기 위해 필요한 용량을 확보할 필요가 없어지므로 시스템 설치비용을 줄일 수 있게 된다.

• Structural Engineering and Mechanics
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• 제66권1호
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• pp.1-14
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• 2018

Column is usually floating on the stone base directly with or without positioning tenon in traditional Chinese timber structure. Vertical load originated by the heavy upper structure would induce large friction force and compression force between interfaces of column foot and stone base. This study focused on the mechanical behaviors of column foot joint with consideration of the influence of vertical load. Mechanism of column rocking and stress state of column foot has been explored by theoretical analysis. A nonlinear finite element model of column foot joint has been built and verified using the full-scale test. The verified model is then used to investigate the mechanical behaviors of the joint subjected to cyclic loading with different static vertical loads. Column rocking mechanism and stress distributions of column foot were studied in detail, showing good agreement with the theoretical analysis. Mechanical behaviors of column foot joint and the effects of the vertical load on the seismic behavior of column foot were studied. Result showed that compression stress, restoring moment and stiffness increased with the increase of vertical load. An appropriate vertical load originated by the heavy upper structure would produce certain restoring moment and reset the rocking columns, ensuring the stability of the whole frame.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.403-407
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• 2009

It is reported that the heavy weight floor impact noise of a slab system is very sensitive to the location of microphone and impact load. In addition, it is known that the aspect raio, thickness and boundary condition of a slab also have great effect on the noise induced by impact load. However, the effect has been mainly evaluated by experimental test and numerical analysis is nearly performed to verify the effect quantitatively. In this study, the effect of the aspect ratio, thickness and boundary condition on the heavy weight floor impact noise is examined through numerical analysis for simple rectangular slab system. The results show that the thickness and boundary condition have a strong correlation with the noise of the slab, on the contrary, the aspect ratio has little relation with the noise.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1050-1052
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• 2005

In this paper, air gap flux density is calculated by permeance model which can consider the effects of the stator slot and the salient pole shape of the salient synchronous generator. No load Electro-motive force(EMF) of the short-pitched and distributed stator winding is also calculated. Therefore, it's very convenient to calculate the THD of the no load EMF for the user's request, in the first design state.

• 한국초전도ㆍ저온공학회논문지
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• 제11권2호
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• pp.33-36
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• 2009

A 1 MW class HTS (High-Temperature Superconducting) synchronous motor has been developed. This motor is aimed to be utilized for industrial application such as large motors operating in large plants. The HTS field coil of the developed motor is cooled by way of neon thermo siphonmechanism and the stator (armature) coil is cooled by water through hollow copper conductor. This paper also describes evaluation of some electrical parameters from performance test results of our motor, which was conducted at steady state in generator mode and motor mode. Open and short circuit tests were conducted in generator mode while a 1.1 MW rated induction machine was rotating the HTS machine. Electrical parameters such as mutual inductance and synchronous inductance are deduced from these tests. Load test was done upto rating torque during motor mode and efficiency was measured at each load torque.

• 대한인간공학회지
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• 제31권1호
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• pp.185-189
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• 2012

Objective: The aim of this paper is to introduces Hyundai Heavy Industry's ergonomic risk assessment tool, H-OWAS, which is considering work load and frequency compared to the OWAS. Background: As prevalence of work-related musculoskeletal disorders(WMSDs) in ship building industries has been much higher than that in other industries, most of the large scaled corporations have implemented their own prevention program since legislation on the prevention of WMSDs had introduced in 2003. Method: This paper introduces WMSDs prevention program, HEMP(HHI Ergonomics Management Program) which consists of risk assessment, improvement efforts of working environments, medical treatment and training/evaluation and describes how to operate the program. We also describe application of OWAS method considering work load and frequency for risk factor analysis(H-OWAS) and shows methodology for assessing the ergonomic risk factor. And comparison of the assessment results between OWAS and H-OWAS is carried out by statistical analysis. Result: There was statistically significant difference in the assessment results between OWAS and H-OWAS, and regression shows H-OWAS explains the borg's scale of perceived exertion more clearly than OWAS. Conclusion: H-OWAS has been proved more effective tool than OWAS to evaluate ergonomic risk factor under real working condition. Application: H-OWAS can be widely applied to the many other companies when implementing the ergonomics risk assessment.