• 한국해양공학회지
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• 제31권6호
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• pp.419-424
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• 2017

Unlike other leisure boats, a sailing yacht is propelled by wind power using sails that are controlled by the crew. Therefore, the ergonomic design of the equipment that the crew has to operate for sailing might be very important. However, it is difficult to find design rules and regulations for the equipment arrangement of a sailing yacht based on ergonomics. In this study, the arrangement design for the height and side plate angle of a winch for a sailing yacht was examined from an ergonomic design point of view. In a simulation, a Korean male in his 20s was selected as a human model for a grinder. The physical load was analyzed when he was operating a winch using a 3D human simulation. The lower back load showed the highest value when using the grinder at $90^{\circ}$ and $180^{\circ}$. Based on the results for the lower back load when using the grinder with various winch heights, it is suggested that the winch height from the cockpit floor to the top of the winch should be more than 40% of the height of the human operator. In addition, according to the results for the lower back load with various horizontal distances from the body, it is suggested that the side plate angle should be less than $16^{\circ}$.

• 대한조선학회 특별논문집
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• 대한조선학회 2009년도 특별논문집
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• pp.107-114
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• 2009

In the recent large block are used to build the ship to improve productivity. For this reason, two or more floating cranes that are connected in parallel is the trend. Typically, when working with floating crane load safety factor is considered. Even in the parallel operation, load safety factor is calculated similar to working alone. For this reason, operations do not guarantee the reliability or excessive safety factor applied. Therefore, the subdivided cases for calculating the safety factor are defined when parallel connected floating cranes are operated. Based on those cases, the operation standard is made about procedure using parallel connected floating cranes. And to verify this, dynamics simulation was performed for verification using the dynamics simulation program.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 춘계학술대회
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• pp.15-16
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• 2014

최근 국제 무역량의 증가에 따라 항만 시스템의 안전하고 효과적인 운용이 중요한 과제로 부각되고 있다. 이러한 배경에서 선박의 접안과정에 대한 시간변위 자동 시뮬레이션 프로그램의 개발이 진행되어 왔고 선박의 속도와 방향 제어를 위해 PD (Proportional Derivative) 제어기가 이용되었다. 이번 연구는 선박 접안과정의 시간 변위 시뮬레이션 프로그램 개발 중 서로 다른 수학적 모델, 즉 선박의 전진속도가 저속일 경우를 위한 Kose (1984)의 모델과 일반적인 전진속도일 경우를 위한 MMG 모델을 이용하여 초기 선수 방향과 선박 위치의 다양한 변화를 적용한 시뮬레이션을 통해 각 방정식의 장점 및 단점을 분석하며 시뮬레이션 구현의 타당성을 검토한다.

• 콘크리트학회논문집
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• 제26권3호
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• pp.343-350
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• 2014

이 연구에서 몬테카를로 시뮬레이션을 이용해 확률론적 시공단계해석을 수행한 이유는 재료 특성, 환경 요인 및 하중에 대한 불확실성의 영향을 고려하기 위해서이다. 지금까지의 연구에서는 크리프 및 건조수축이 완전히 독립적인 확률 변수라고 가정되었다. 그러나 크리프 및 건조수축 추정을 위한 재료모델의 공통적인 영향요인 때문에 크리프 및 건조수축 사이에 강한 상관관계를 추정 할 수 있다. 이 논문에서는 CEB-FIB모델의 크리프 및 건조수축식을 이용하여 몬테카를로 시뮬레이션을 수행하여 실제 두 현상 사이의 상관 계수를 평가 한 후 재료 특성, 환경 요인 및 하중의 확률 변수의 영향을 받는 축방향 변형의 통계적 특성을 평가하기위해 몬테카를로 시뮬레이션을 한번 더 사용하였다. 몬테카를로 시뮬레이션의 결과는 58층 건물의 첫 번째 층의 기둥의 변형률과 비교 했다. 비교 결과는 재료특성에 불확실성에 의한 변화가 가장 큰 것으로 나타났다. 측정된 변형률은 평균+표준 편차 범위 안에 있었다.

• 한국컴퓨터정보학회논문지
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• 제25권8호
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• pp.31-37
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• 2020

본 논문에서는 사이버 전투실험 분석이 가능한 사이버 킬체인 및 MITRE ATT&CK 기반의 시스템 구성 및 분석 방법론을 제안한다. 사이버 킬체인을 기반으로 공격 과정을 모의하고, MITRE ATT&CK를 기반으로 공격 목적 및 구체적인 공격 방법을 적용하여, 실제 발생한 다양한 공격 및 새롭게 등장할 공격에 대한 시스템 위협 분석이 가능하도록 한다. 또한, 현 시스템(AS-IS)과 새로운 대응 시스템이 적용될 경우(TO-BE)에 대한 사이버 공격 및 대응 측면의 효과도 분석을 정량적으로 제시하여, 선제적 방어방책 및 소요 반영을 위한 의사결정에도 활용이 가능하다. 제안하는 시스템 및 방법론의 활용성을 제시하기 위해, 테스트베드 환경에서 프로토타입을 구축하고 사례 연구를 수행하였다. 제안된 방안은 사이버 전투실험의 기술 수준을 높여 사이버전 역량 강화에 기여할 것으로 기대한다.

• 대한조선학회논문집
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• 제58권1호
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• pp.1-9
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• 2021

In the present study, the model-scale Propeller Open Water (POW) tests for the propeller of 176K bulk carrier and 8600TEU container ship were conducted through Computational Fluid Dynamics (CFD) simulation. In order to solve the incompressible viscous flow field, the Reynolds-averaged Navier-Stokes (RaNS) equations were employed as the governing equations. The γ-Reθ(gamma-Re-theta) transition model combined with the SST k-ωturbulence model was introduced to describe the laminar-turbulence transition considering the low Reynolds number of model-scale. Firstly, the flow simulation developing over a flat plate was performed to verify the transition modeling, in which the wall shear stresses were compared with experiments and other numerical results. Then, to investigate the effect of the model, the CFD simulation for the POW test was performed and the simulated propeller performance was validated through comparison with the experiment conducted at Korea Research Institute of Ships & Ocean Engineering (KRISO).

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.491-500
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• 2020

The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.213-225
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• 2020

Floating Offshore Wind Turbines (FOWT) installed in the deep sea regions where stable and strong wind flows are abundant would have significantly improved energy production capacity. When designing FOWT, it is essential to understand the stability and motion performance of the floater. Water tank model tests are required to evaluate these aspects of performance. This paper describes a model test and numerical simulation for a 750-kW semi-submersible platform wind turbine model-II. In the previous model test, the 750-kW FOWT model-I suffered slamming phenomena from extreme wave conditions. Because of that, the platform freeboard of model-II was increased to mitigate the slamming load on the platform deck structure in extreme conditions. Also, the model-I pitch Response Amplitude Operators (RAO) of simulation had strong responses to the natural frequency region. Thus, the hub height of model-II was decreased to reduce the pitch resonance responses from the low-frequency response of the system. Like the model-I, 750-kW FOWT model-II was built with a 1/40 scale ratio. Furthermore, the experiments to evaluate the performance characteristics of the model-II wind turbine were executed at the same location and in the same environment conditions as were those of model-I. These tests included a free decay test, and tests of regular and irregular wave conditions. Both the experimental and simulation conditions considered the blade rotating effect due to the wind. The results of the model tests were compared with the numerical simulations of the FOWT using FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code from the National Renewable Energy Laboratory (NREL).

• Architectural research
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• 제12권2호
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• pp.1-7
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• 2010

Science (natural science) is the systematic attempt to understand and interpret the nature phenomenon. For this reason, architects have used science to adapt nature to their design. With the rise of modern science, architecture became more closely related with science. Science available to develop new technology for architecture and it influenced architect's idea and concept. Symbolically, Architects use method or process of science to generate building form. The Rules of compositing particles in the chemistry or DNA (deoxyribonucleic acid) in the biology are used to generate a form of building. Literally, Architects use technology as a tool of science to improve physical performance of architecture. Like mathematical understanding of structure load enabled people to construct enclosure without columns or any of support system inside of architecture. Still natural phenomenon is not fully understood as science and science is still discovering a new phenomenon or changing its theory to adapt new discovery. New discovery or limitation of science influenced architecture throughout the history. This paper is to discuss how architectural theories are rest upon idea set forth by science. In addition, how technology as a tool of science has been utilized in architecture.

• 한국산업정보학회논문지
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• 제10권3호
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• pp.57-63
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• 2005

Kim과 Fenn등은 LFSR 구조를 이용한 두 가지 구조의 효율적인 모듈러 AB 곱셈기를 구현하였다. 그들의 구조는 기약다항식으로 모든 계수가 1인 속성의 AOP를 이용함으로서 기존의 곱셈기들보다 효율적인 구조복잡도를 가졌다. 본 논문에서는 Kim의 곱셈기보다 효율적인 공간 복잡도를 가진 LFSR(Linear Feedback Shift Register) 구조 기반의 모듈러 $AB^2$ 곱셈기와 모듈러 지수승기를 제안한다. 본 논문에서 제안한 구조도 Kim의 구조에서와 같이 기약다항식으로 AOP를 사용한다. 시뮬레이션 결과 본 논문에서 제안한 $AB^2$ 곱셈기가 구조복잡도 면에서 Kim의 구조보다 XOR와 AND 게이트의 개수를 약 $50\%$ 정도 줄일 수 있었다. 제안한 구조는 공개키 암호화 시스템을 위한 기본구조로 사용될 수 있을 것이다.