• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.91-99
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• 2020

A liquid rocket engine goes through many tests to prove its performance before liftoff. It means the tests for setting ignition and start-up conditions or a test on design condition, which verifies the design performance. However, the development process requires verification of performance under off-design conditions through tests involving different operating conditions, which affects the duration of engine development. The off-design performance test is performed by altering the conditions of the propellant supplied to the engine in conjunction with the engine performance test that varies the opening of the control valves in the engine. This paper is based on the results of the engine tests performed at the KSLV-II engine test facilities in the Naro Space Center and describes the operations of the test facility for off-design condition test that changes the inlet conditions of the turbo-pump due to changes in the pressure and temperature of the propellant supplied to the test engines.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.51-56
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• 2010

There are two main software in COMS ground station at the normal mode operation - stationkeeping and wheel off-loading. In this paper, ground software validation test for wheel off-loading is summarized and described. The wheel off-loading was performed the design change from E3000 heritage and analyzed. The wheel off-loading of ground software has two part; one is wheel off-loading management for parameters change at the thruster set switching time and the other is wheel off-loading set-point being sent to satellite for the reference momentum.

• The KSFM Journal of Fluid Machinery
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• v.17 no.3
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• pp.5-12
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• 2014

This paper presents a design optimization for meridional profile and blade angle ${\theta}$ of a centrifugal compressor with DOE (design of experiments) and RSM (response surface method). Control points of the $3^{rd}$ order Bezier curve are used for design parameters and specific overall efficiency is used as object function. The response surface function shows good agreement with the 3D computational results. Three different optimized designs are proposed and compared with reference design at design point and off-design point. Contours of relative Mach number, static entropy, and total pressure are analyzed for improvement of performance by optimization. Off-design performance analysis is conducted by total pressure and efficiency.

• Journal of Ocean Engineering and Technology
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• v.34 no.1
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• pp.19-25
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• 2020

This paper proposes the optimal shape of an LNG fuel tank with a lattice pressure vessel (LPV) design for a tugboat. The LPV is a Type C tank with a design philosophy of "design by analysis," which facilitates greater variability of shape compared with other traditional Type C tanks. Further, compared with conventional cylindrical fuel tanks, the LPV provides better volumetric efficiency. Considering the shape of a fuel tank room, a trapezoidal shape of the LPV is concluded as the most optimal design. This study performs two major analyses of the LPV: structural and heat transfer analyses. First, a design procedure of the LPV based on structural analyses is elaborated. The finite element method is used for the analyses. Furthermore, the results guarantee that the maximum stresses by applied loads do not exceed an allowable stress limitation. Second, the heat transfer analysis of the LPV is conducted. LNG boil-off gas generation is analyzed based on various insulation materials and the degree of acuum.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.272-285
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• 2004

The losses at off-design points from a compressor cascade occur due to the deviation from a design incidence angle at the inlet of the cascade. The self-noise from the blade cascade at off-design points comes from a separated boundary layer and vortex sheddings. If the incidence angle to the cascade increases, stalling in blades may occur and the noise level increases significantly. This study applied Large-Eddy Simulations (LES) using deductive and deductive dynamic SGS models to low Mach-number, turbulent flow with each incidence angle to the cascade ranging from -40$^{\circ}$ to +20$^{\circ}$ and compared numerical predictions with measured data. It was observed that the oscillating separation bubbles attached to the suction surface do not modify wake flows dynamically for cases of negative incidence angles. However, an incidence angle greater than 8$^{\circ}$ caused a separated vortex near the leading edge to be shed downstream and created stalling. The computed performance parameters such as drag coefficient and total pressure loss coefficient showed good agreement with experimental results. Noise from the cascade of the compressor is summarized as sound generated by a structure interacting with unsteady, turbulent flows. The hybrid method using acoustic analogy was observed to closely predict the measured overall sound powers and directivity patterns at design and off-design points of blade cascade.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.32-40
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• 2017

In this study, an in-house program to analyze the performance degradation for gas turbines is developed using MATLAB and is validated using commercial software. This program consists of design and off-design calculations. The results of design calculation is used for reference values of off-design calculation. The off-design calculation is composed of measured and expected performance analyses, and turbine inlet temperature correction. In general, performance degradation is analyzed by comparing the results of measured and expected performance analysis. However, if gas turbine performance degrades, turbine inlet temperature might increase due to the general control logic to comply with the power demand. Therefore, it is required to consider the deviation of turbine inlet temperature from the normal value in the performance diagnosis to analyze the performance degradation exactly. In this study, a special effort is given to the correction of turbine inlet temperature. The accuracy of the developed program is confirmed by comparison with commercial software, and its capability of performance diagnosis using the turbine inlet temperature correction is demonstrated.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.72-76
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• 2003

This paper presents the design concept and operation results of float-off for FSO (340,000 DWT Class, ELF AMENAM KPONO Project) built on the ground, without dry dock facilities. It was the first attempt to build FSO, completely, on the ground and launch it using DBU (Double Barge Unit, which was connected by rigid frame structure.) The major characteristics of FSO, which are similar to general VLCC type hull, including topside structure, weigh 51,000 metric ton. In order to have sufficient stability during the deck immersion of DBU, while passing through a minimum water plane area zone, proper trim control was completed with LMC (Load Master Computer). The major features of the monitoring system include calculation for transverse bending moment, shear force, local strength check of each connector, based on component stress, and deformation check during the load-out and float-off. Another major concern during the operation was to avoid damages at the bottom and sides of FSO, due to motion & movement after free-floating; therefore, adequate clearances between DBU and FSO were to be provided, and guide posts were installed to prevent side damage of the DBU casings. This paper also presents various measures that indecate the connector bending moment, damage stability analysis, and mooring of DBU during float off.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.169-177
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• 2006

In this study, we present the optimization of a head slider using kriging method in order to reduce lift-off force during unloading process with satisfying reliable flying attitude in steady state. To perform an optimization process efficiently, a simplified lift-off force model, which is a function of air bearing suction force and flying attitudes, is created by kriging method. The EMDIOS, which is the process integration and design optimization software developed by iDOT, is used to automatically wrap the analysis with the optimization and efficiently implements the repetitive works between analyzer and optimizer. An optimization problem is formulated to reduce the lift-off force during unloading process while satisfying the flying attitude in reliable range over the entire recording band and reducing the probability of contact between slider and disk. The simulation result shows that the amplitude of lift-off force of optimized L/UL slider is reduced about 62%, compared with that of initial slider model. It is demonstrated by the dynamics L/UL simulation that the optimum slider incorporated with the suspension is not only smoothly loaded onto disk but also properly unloaded onto the ramp.

• Current Optics and Photonics
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• v.6 no.1
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• pp.44-50
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• 2022

An off-axis zone plate is able to focus on a single order while neglecting the zeroth order in a visible imaging system. This allows one to enhance the contrast quality in diffractive images, which is the major advantage of this type of zone plate. However, most previous reflection zone plates are used in focusing X-rays with a small grazing incident angle and are intricately designed with the use of a local grating period. In this study, we suggest the design of an off-axis elliptical zone plate (EZP) that is used to focus a monochromatic light beam with separation between the first and unfocused orders under a large grazing incident angle of 45°. An assumption using the total grating period, which depends on the average and constant grating period, is proposed to calculate the desired distance between the first and zeroth order and to simplify the construction of a novel model off-center EZP. Four diffractive optical elements (DOEs) with different parameters were subsequently fabricated by direct laser lithography and then verified using a performance evaluation system to compare the results from the assumption with the experimental results.

• Korean Institute of Interior Design Journal
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• v.15 no.5 s.58
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• pp.95-103
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• 2006

Ron Arad, the master of contemporary design in the U.K., is one of representative leaders of this age who has left distinguished achievements in the history of contemporary design through innovative design. Analyzing and understanding the Deconstructive design concept and the deconstructive characteristics of interior space of Ron Arad will contribute to finding directions for today's design and laying the ground for explaining the development pattern of design in the 21st century. After analyzing the deconstructive characteristics of each selected space, One Off and Ron Arad Associates have shown a deconstructive design trend of a creative formula by using methods that shed conventional processes and material while a space composition and form of new concept was attempted in the resting space of the New Tel Aviv Opera House, offering not only the establishment of a new circulation system, but also diverse experiences of space to visitors. Likewise, a temporal experience and communication between the user and the space was attempted in Belgo Noord and Belgo Central by partially applying a narrative space composition that sheds existing design concepts. At the Millennium House, they have produced an interior space for future house developed by breaking off from existing typical design development work and material through computer operation, and made various forms of space and atmosphere possible by attempting variable elements and the use of ultramodern material. Y's fashion shop has granted variability to the form and volume of space according to time by presenting display elements that have shed existing form and function. Hotel Puerta America as well, with a curved structure that has broken off with existing forms and maximized space variability through structures that have utilized ultramodern materials and instruments. Through this study, it has been verified that Ron Arad has been unraveling connections between interior space and its user, its requirements, and the original unique principles of space by applying deconstructive design concepts, and that through the mediation of these spaces, he is attempting indirect communication with the user. Eventually, he is taking part in the harmony and development of all elements of space connected with human beings by applying deconstructive design concepts.