• International Journal of Automotive Technology
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• 제8권1호
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• pp.93-102
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• 2007

The frontal crash optimization of an engine room member using the response surface method was studied. The engine room member is composed of the front side member and the sub-frame. The thicknesses of the panels on the front side member and the sub-frame were selected as the design variables. The purpose of the optimization was to reduce the weight of the structure, under the constraint that the objective quantity of crash energy is absorbed. The response surface method was used to approximate the crash behavior in mathematical form for optimization procedure. To research the effect of the regression method, two different methodologies were used in constructing the response surface model, the least square method and the moving least square method. The optimum with the two methods was verified by the simulation result. The precision of the surrogate model affected the optimal design. The moving least square method showed better approximation than the least square method. In addition to the deterministic optimization, the reliability-based design optimization using the response surface method was executed to examine the effect of uncertainties in design variables. The requirement for reliability made the optimal structure be heavier than the result of the deterministic optimization. Compared with the deterministic optimum, the optimal design using the reliability-based design optimization showed higher crash energy absorption and little probability of failure in achieving the objective.

• Ocean Systems Engineering
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• 제1권1호
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• pp.73-93
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• 2011

Large deck openings of ultra large container ships reduce their torsional stiffness considerably and hydroelastic analysis for reliable structural design becomes an imperative. In the early design stage the beam model coupled with 3D hydrodynamic model is a rational choice. The modal superposition method is ordinary used for solving this complex problem. The advanced thin-walled girder theory, with shear influence on both bending and torsion, is applied for calculation of dry natural modes. It is shown that relatively short engine room structure of large container ships behaves as the open hold structure with increased torsional stiffness due to deck effect. Warping discontinuity at the joint of the closed and open segments is compensated by induced distortion. The effective torsional stiffness parameters based on an energy balance approach are determined. Estimation of distortion of transverse bulkheads, as a result of torsion and warping, is given. The procedure is illustrated in the case of a ship-like pontoon and checked by 3D FEM analysis. The obtained results encourage incorporation of the modified beam model of the short engine room structure in general beam model of ship hull for the need of hydroelastic analysis, where only the first few natural modes are of interest.

• 한국산업융합학회 논문집
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• 제22권5호
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• pp.553-559
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• 2019

Various types of nozzles have been used to cope with fire in ships. However, in Korea, precise nozzles that perform fine spraying function are required for fire fighting in case of fire in a ship, and most of these nozzles depend on imports. Therefore, in this study, we developed various types of nozzles to develop the water spray nozzle for evolving fire in the engine room of the ship, and developed an optimal nozzle through flow analysis and fire test. For this purpose, we selected the materials that can satisfy the characteristics of existing nozzle materials and developed the design technology and processing technology in the nozzle considering fluid flow to achieve optimal water spraying performance. In order to develop an optimal nozzle, the flow through the finite element analysis was first analyzed and the nozzle was manufactured. As a result of flow analysis of the developed nozzle, the maximum velocity at the outlets of four holes at 0.3 MPa was about 3m/s and about 0.15 MPa. In addition, when the pressure at the inlet was 1.8 MPa, it showed the outlet speed of about 18m/s and a pressure of 1.2 MPa.

• 에너지공학
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• 제27권4호
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• pp.98-102
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• 2018

자동차 엔진룸내 부품의 내구성 향상을 위하여 냉각 가능성을 판단하고자 발전기, 배터리, ECU 및 파워스틸 오일 등 4가지 부품을 목표로 흡입공기를 사용한 냉각용 덕트를 설치하여 부품에 대한 공랭효과를 향상시키기 위한 실험을 수행하였다. 실험 결과, 전반적으로 부품 온도가 저감되었으며 감소된 온도 차이는 발전기, ECU, 파워스틸 오일 및 배터리 순으로 크게 나타났다. 이러한 부품에 따른 온도 차이를 개선하기 위해서는 차후에 덕트 내부에 대한 유동해석을 통한 최적화 설계가 필요하다고 판단된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.116-121
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• 2002

Axial fans are widely used in heavy machines due to their ability to produce high flow rate for cooling of engines. At the same time, the noise generated by these fans causes one of the most serious problems. This work is concerned with the low noise technique of discrete frequency noise. To calculate the unsteady resultant force over the fan blade in an unsymmetric engine room. Time-Marching Free-Wake Method is used. From the calculations of unsteady force on fan blades, noise signal of an engine cooling fan is calculated by using an acoustic similarity law. Noise optimization is obtained from Neural Network which is constructed based on the calculated flow rate and noise spectrum.

• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.270-278
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• 2002

In order to reduce the exhaust emissions of a spark ignition engine, it is important not only to improve the catalyst conversion efficiency, but also to directly reduce the engine-out exhaust emissions during a cold starting of the engine and warm up periods. The purpose of this study is to evaluate feasibility of a glow plug for an early fuel evaporator. In order to promote atomization, gasoline is injected on the glow plug with room temperature(20$\^{C}$) and high temperature(250$\^{C}$). To analyze the spray behavior characteristics, a PMAS is used to measure the SMD and the dropsize distribution of an impinging spray and a free spray. Results show that the evaporation rate of the impinging spray on the high temperature surface of the glow plug was higher than that of the free spray on the room temperature surface.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.42-49
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• 2008

Most of vessels are not evaluated for their vibration and noise effects to human body. The vibration and noise generated by engine and auxiliary machine in vessel is a negative element for seamen. Therefore, in this paper, the diagnosis and evaluation of vibration and noise from vessel is accomplished by a shipbuilding corporation. The vibration and noise transferred from engine room and auxiliary machine was measured during the steady-state operation, and the vibration and noise map of vessel was made. Also, in order to evaluate the ship environment for human, the diagnosis is carried out on the base of measurement results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.318.2-318
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• 2002

Axial fans are widely used in heavy machines due to their ability to produce high flow rate fur cooling of engines. At the same time, the noise generated by these fans causes one of the most serious problems. This work is concerned with the low noise technique of discrete frequency noise. To calculate the unsteady resultant force over the fan blade in an unsymmetric engine room, Time-Marching Free-Wake Method is used. From the calculations of unsteady force on fan blades, noise signal of an engine cooling fan is calculated by using an acoustic similarity law. (omitted)

• 한국기계기술학회지
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• 제13권2호
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• pp.9-19
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• 2011

Most real world design evaluation and risk-based decision support combine quantitative and qualitative (linguistic) variables. Decision making based on conventional mathematics that combines qualitative and quantitative concepts always exhibit difficulty in modelling actual problems. The successful selection process for choosing a design/procurement proposal is based on a high degree of technical integrity, safety levels and low costs in construction, corrective measures, maintenance, operation, inspection and preventive measures. In this paper, a design decision support framework using a composite structure methodology grounded in approximate reasoning approach and evidential reasoning method is suggested for design evaluation of machinery space of a ship engine room at the initial stages. An illustrative example is used to demonstrate the application of the proposed framework.

• International journal of advanced smart convergence
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• 제7권4호
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• pp.114-120
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• 2018

The purpose of this paper is to develop simulations that can be used for virtual education in dentistry. This development goal is to allow dental students to learn the necessary surgical techniques at the point of their choice, not going into the operating room, away from time, space, and physical limits. In this paper configuration, the optimization method is applied convergent, and when the operation of the VR contents is performed, the content data is extracted from the interaction analysis formed in the VR engine, and the data is processed by the content algorithm. It also computes events and dental operations generated within the 3D engine programming and generates corresponding events through data processing according to the input signal. The visualization information is output to the HMD using the rendering information. In addition, the operating room environment was constructed by studying lighting and material for actual operating room environment. We applied the ratio of actual space to virtual space and the ratio between character and actual person to create a spatial composition at a similar rate to actual space.