• 해양환경안전학회지
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• 제28권2호
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• pp.346-353
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• 2022

최근 회전 회전기계의 건전성 관련 연구가 활발하게 진행중이며, 조선업의 대표적인 회전기계인 갠트리 크레인에도 이를 적용하고자 하는 연구가 활발하게 진행되고 있다. 하지만 조선업의 갠트리 크레인의 경우 상대적으로 낮은 RPM으로 구동되고 잦은 운전과 정지가 이루어지며 충격, 소음 등의 외부환경 인자가 측정 데이터에 영향을 크게 미쳐 오차를 발생시킬 수 있다. 본 연구에서는 조선업의 내업공정에서 사용되는 갠트리 크레인의 Hoist 모사장비를 제작하여, 운전조건(RPM) 변화와 데이터 획득 센서의 위치 차이가 획득 데이터에 미치는 오차를 통계적으로 분석하였다. 연구결과 상대적으로 낮은 운전조건에서는 센서 위치 차이에 따른 획득 데이터의 오차는 크게 발생하지 않았으나, 상대적으로 높은 운전조건에서는 획득 데이터의 오차가 크게 발생하는 것으로 확인하였으며, 회전기계의 데이터 획득 시 운전조건과 획득 센서위치가 획득 데이터에 영향을 미치는 것으로 확인하였다.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1129-1136
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• 2010

체결클러치에 부착된 댐퍼스프링은 유체커플링에서 직결로 변환될 때 발생하는 엔진 토크의 진동을 흡수하는 역할을 한다. 본 연구에서는 체결클러치의 성능을 좌우하는 압축스프링 및 지지 판 구조물의 최적설계를 통해서 새로운 설계형상을 제안하였다. 체결클러치와 연결된 엔진, 변속기, 구동축 및 휠, 차체질량 등 주요 부품들을 다 포함하는 다물체 동역학모델을 구성하여 공진 회피에 필요한 스프링상수를 계산하였다. 또한 어닐링 모사법에 의한 스프링 최적설계코드를 개발한 후 스프링상수, 최대충격토크, 수축각도, 스프링개수, 피로강도 등을 입력하여 압축 스프링의 사양을 최적화하였다. 이들 스프링을 지지하는 3 가지의 판에 대해서 컴플라이언스를 최소화하고 체적비를 0.3 이하로 하는 위상최적화를 수행하여 새로운 형상을 제안하였다.

• 한국지진공학회논문집
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• 제9권4호
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• pp.43-54
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• 2005

다양한 지진 규모 및 주파수 특성을 가지는 지반운동에 대하여 사장교에 장착된 준능동 제어시스템의 제어효과를 분석하고 비용효율성을 평가하였다. Dyke 등에 의하여 제시된 벤치마크 사장교 제어문제에 준능동 제어시스템을 설계하였으며, LQG 최적제어기에 기반한 bi-state 제어방법을 적용하였다. 제어시스템의 비용효율성은 제어시스템을 장착하지 않은 교량의 생애주기 비용에 대한 제어시스템을 장착한 교량의 생애주기비용의 비로서 정의하였으며, 손상비용 규모와 준능동 제어장치의 가격을 매개변수로 하여 그 변화에 따른 비용효율성 평가를 수행하였다. 분석 결과, 제어시스템의 경제적 효율성은 준능동 제어장지의 가격에 크게 민감하지 않은 반면, 손상비용 규모에 따라 민감하게 변화하였다. 또한 중진규모의 연약지반과 강진규모의 견고한 지반에 해당하는 지반운동에 대하여 준능동 제어시스템의 비용효율성이 높은 것으로 평가되었다.

• 한국전산구조공학회논문집
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• 제28권4호
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• pp.361-368
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• 2015

최근 지진의 빈도가 증가하면서 전력 시설물에 대한 피해 역시 심각한 상황이다. 요즘 들어 Hanger, Brace, Snubber와 같이 주요기기들을 연결하는 배관지지 시스템의 중요성이 강조되고 있다. 배관의 손상은 발전소 가동에 전체적인 영향을 미치기 때문에 손상을 주는 요인으로부터 보호할지지 장치가 필요하게 된다. 이러한 장치들은 배관에 작용하는 직 간접적인 진동과 충격을 저감시키는 역할을 하기 때문에 배관의 손상을 방지할 수 있다. 본 논문에서는 마찰진자 원리를 이용한 기계식 댐퍼를 개발하고 특성시험을 통해 장치 성능을 검증한 내용을 기술하였다. 또한 자체 개발한 설계 프로그램을 통해 예상된 해석값과 시험값을 비교분석하였고 결과적으로 설계의 신뢰성을 향상시켰다.

• International Journal of Computer Science & Network Security
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• 제21권6호
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• pp.252-257
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• 2021

The application of the principle of trigeneration allows to simultaneously provide electricity to power electronic devices, as well as heat and cold to create the necessary microclimate of the premises and increase efficiency compared to separate cooling and heating systems. The use of Peltier thermoelectric modules (TEM) as part of trigenerative systems allows for smooth and precise control of the temperature regime, high manufacturability and reliability due to the absence of moving parts, resistance to shock and vibration, and small weight and size parameters of the system. One of the promising areas of improvement of trigenerative systems is their modeling and optimization based on the automatic control theory. A block diagram and functional model of an energy-saving trigenerative climate control system based on Peltier modules are developed, and the transfer functions of an open and closed system are obtained. The simulation of the transient characteristics of the system with varying parameters of the components is performed. The directions for improving the quality of transients in the climate control system are determined, as well as the prospects of the proposed methodology for modeling and analyzing control systems operating in substantially nonlinear modes.

• 한국기계가공학회지
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• 제16권3호
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• pp.54-62
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• 2017

When gears mesh, shock and noise are produced as results of tooth error and tooth deformation under load. Transmission error (TE) is the most important cause of gear noise and vibration because TEs affect the changes of the force and the speed of gears. Gear tooth modification research plays a positive role in reducing TE and improving the design level and transmission performance of transmission systems. In high-precision manufacturing gear, gear tooth modification is also commonly used to reduce noise in practical applications. In order to study the accuracy of gear transmission, some empirical gear profile micro-modifications are introduced, and a helical gear pair is modeled and analyzed in RomaxDesigner software to investigate the utility of these modification methods. Some of these will be selected as experimental proposals for gear pairs, and these manufactured gears will be tested and compared in a semi-anechoic room later. The final purpose of this study is to find reasonable and convenient empirical formulae to facilitate improved gear production.

• Steel and Composite Structures
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• 제4권2호
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• pp.149-167
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• 2004

Offshore platforms have to serve in harsh environments and hence are likely to be damaged due to wave induced fatigue and environmental corrosion. Welded tubular joints in offshore platforms are most vulnerable to fatigue damage. Such damages endanger the integrity of the structure. Therefore it is all the more essential to assess the capacity of damaged structure from the point of view of its safety. Eight internally ring stiffened fatigue damaged tubular joints with nominal chord and brace diameter of 324 mm and 219 mm respectively and thickness 12 mm and 8 mm respectively were tested under axial brace compression loading to evaluate the reserve capacity of the joints. These joints had earlier been tested under fatigue loading under corrosive environments of synthetic sea water and hence they have been cracked. The extent of the damage varied from 35 to 50 per cent. One stiffened joint was also tested under axial brace tension loading. The residual strength of fatigue damaged stiffened joint tested under tension loading was observed to be less than one fourth of that tested under compression loading. It was observed in this experimental investigation that in the damaged condition, the joints possessed an in-built load-transfer mechanism. A bi-linear stress-strain model was developed in this investigation to predict the reserve capacity of the joint. This model considered the strain hardening effect. Close agreement was observed between the experimental and predicted results. The paper presents in detail the experimental investigation and the development of the analytical model to predict the reserve capacity of internally ring stiffened joints.

• 한국안전학회지
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• 제29권4호
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• pp.172-179
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• 2014

This research suggests that the regulation, design and improvement of domestic and international ambulances so that make the basis for the future ambulance in Korea. It is true that the diversification of current disasters, increasing elderly population, the increase in emergency patients, due to the lack of effective transfer system, emergency vehicle's performance problem, and the aging of ambulances cause have difficulty in providing effective emergency services in domestic country. Therefore, in order to improve the effectiveness of ambulance, the history of ambulance, other relevant provisions include international, design and directions to be improved were investigated, and also research directions of the ambulance are suggested in domestic country. In this research, suggests the following conclusions to improve domestic ambulance 1. Through standardization of the spacing and location of an ambulance is needed to maximize the treatment room. 2. The interior of the ambulance design for hygiene and infection control should be included. 3. Stretcher and equipment are designed to be fitted to each other should be standardized. 4. Especially during transfer maintain the road, noise, vibration, and shock-absorbing function to emphasize the importance. 5. The improvement of ergonomic design is necessary for the possibility of applying to many people.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4125-4133
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• 2023

The transportation of spent nuclear fuel is an important process that involves road and sea transport from an interim storage facility to storage and final disposal sites. As spent nuclear fuel poses a significant risk, carefully evaluating its vibration and shock characteristics under normal transport conditions is essential. In this regard, full-scale multi-modal transport tests (MMTT) have been conducted domestically and internationally. In this paper, we discuss the process of developing a multi-body dynamics (MBD) model to analytically simulate conditions that cannot be considered in tests. The MBD model is based on the KORAD-21 transportation system was validated using the Korean MMTT results from 2020 to 2021. This paper summarizes the details of the development and verification of the MBD model for the KORAD-21 transportation system under normal transport test conditions. This approach can be applicable to various transportation scenarios and systems, and the results of this study will help to ensure that nuclear fuel transportation is conducted safely and effectively.

• 한국전산유체공학회지
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• 제13권1호
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• pp.35-40
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• 2008

Generally flight vehicles have many cavities such as wheel wells, bomb bays and windows on their external surfaces and the flow around these cavities makes separation, vortex, shock and expansion waves, reattachment and other complex flow phenomenon. The flow around the cavity makes abnormal and three-dimensional noise and vibration even thought the aspect ratio (L/D) is small. The cavity giving large effects to the flow might make large noise, cause structural damage or breakage, harm the aerodynamic performance and stability, or damage the sensitive devices. In this study, numerical analysis was performed for cavity flows by the unsteady compressible three dimensional Reynolds-Averaged Navier-Stokes (RANS) equations with Wilcox's $\kappa-\omega$ turbulence model. The MPI(Message Passing Interface) parallelized code was used for calculations by PC-cluster. The cavity has the aspect ratios of 2.5, 3.5 and 4.5 with the W/D ratio of 2 for three-dimensional cavities. The Sound Pressure Level (SPL) analysis was done with FFT to check the dominant frequency of the cavity flow. The dominant frequencies were analyzed and compared with the results of Rossiter's formula and Ahuja& Mendoza's experimental datum.