• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.5
• /
• pp.542-550
• /
• 2007

A geometry modification is one of main keys in achieving a successful optimization. The optimized hull form generated from the geometry modification should be a realistic, faired form from the ship manufacturing point of view. This paper presents a practical hull optimization procedure using a parametric modification function. In the parametric modification function method, the initial ship geometry was easily deformed according to the variations of design parameters. For example, bulbous bow can be modified with several parameters such as bulb area, bulb length, bulb height etc. Design parameters are considered as design variables to modify hull form, which can reduce the number of design variables in optimization process and hence reduce its time cost. To verify the use of the parametric modification function, optimization for KCS was performed at its design speed (FN=0.26) and the wave making resistance is calculated using a well proven potential code with fully nonlinear free surface conditions. The design variables used are key design parameters such as Cp curve, section shape and bulb shape. This study shows that the hull form optimized by the parametric modification function brings 7.6% reduction in wave making resistance. In addition, for verification and comparison purpose, a direct geometry variation method using a bell-shape modification function is used. It is shown that the optimal hull form generated by the bell-shaped modification function is very similar to that produced by the parametric modification function. However, the total running time of the parametric optimization is six times shorter than that of the bell shape modification method, showing the effectiveness and practicalness from a designer point of view in ship yards.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2001.05a
• /
• pp.43-46
• /
• 2001

We, in this paper, design the Sugeno-models fuzzy controller by using the membership function modification algorithm and ANFIS, which are clustering and learning the input-output data. The membership function modification algorithm constructs the more concrete fuzzy controller by clustering the input-output data from the fuzzy inference system. ANFIS construct the Sugeno-models fuzzy controller by learning the input-output data from the above controller. We showed that the fuzzy controller designed by our method could have the stable learning and the enhanced performance.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.5
• /
• pp.1193-1201
• /
• 1993

A new deformation resistance model for hot steel strip rolling process was formulated to improve the accuracy of roll force estimation. To improve the existing deformation resistance model more precisely, a modification function was introduced in this study. For the modification function, several factors considering material and operational conditions have been investigated and the optimal modification function was determined under the principle of minimum variability. The newly formulated modification function was applied to the deformation resistance model for ultra-low carbon steel and showed improved accuracy with about 30% decrease in terms of standard deviation of predicted roll force values against measured ones.

• ETRI Journal
• /
• v.39 no.1
• /
• pp.76-86
• /
• 2017

In this study, we propose an automatic contrast enhancement method based on transfer function modification (TFM) by histogram equalization. Previous histogram-based global contrast enhancement techniques employ histogram modification, whereas we propose a direct TFM technique that considers the mean brightness of an image during contrast enhancement. The mean point shifting method using a transfer function is proposed to preserve the mean brightness of an image. In addition, the linearization of transfer function technique, which has a histogram flattening effect, is designed to reduce visual artifacts. An attenuation factor is automatically determined using the maximum value of the probability density function in an image to control its rate of contrast. A new quantitative measurement method called sparsity of a histogram is proposed to obtain a better objective comparison relative to previous global contrast enhancement methods. According to our experimental results, we demonstrated the performance of our proposed method based on generalized measures and the newly proposed measurement.

• Molecules and Cells
• /
• v.19 no.2
• /
• pp.157-166
• /
• 2005

Transfer RNA (tRNA) is a key molecule to decode the genetic information on mRNA to amino aicds (protein), in a ribosome. For tRNA to fulfill its adopter function, tRNA should be processed into the standard length, and be post-transcriptionally modified. This modification step is essential for the tRNA to maintain the canonical L-shaped structure, which is required for the decoding function of tRNA. Otherwise, it has recently been proposed that modification procedure itself contributes to the RNA (re)folding, where the modification enzymes function as a kind of RNA chaperones. Recent genome analyses and post-genome (proteomics and transcriptomics) analyses have identified genes involved in the tRNA processings and modifications. Furthermore, post-genomic structural analysis has elucidated the structural basis for the tRNA maturation mechanism. In this paper, the recent progress of the structural biology of the tRNA processing and modification is reviewed.

• Journal of the Society of Naval Architects of Korea
• /
• v.59 no.2
• /
• pp.96-108
• /
• 2022

In this paper, we propose a systematic hull form variation technique which automatically satisfies the displacement constraint and guarantees a high level of fairness. This method is possible through multiple parameter correction curves. The present method is to improve the hull form variation method based on parametric modification function and consists of two sub-categories: SAC variation and section lines modification. For SAC variation, the utilization of two B-Spline curves satisfying GC¹ condition led to the satisfaction of displacement constraint and high level of fairness at the same time. Section lines modification methods involves in using two fuctions: the first is the waterplane modification function combining two cubic splines. the other function is the sectional area modification function consisting of 2nd order polynomial over the DLWL(Design Load Waterline) and 3rd order polynomial below the DLWL, This function enables not only the fundamental U-V section shape variation but also systematically modified section lines. The present method is expected to be more useful in the hull form optimization process using CFD compared to the existing method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.12
• /
• pp.3782-3791
• /
• 1996

A great deal of effert has been invested in upgrading the performance and the efficiency of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, this performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircraft, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure based on that of the composing structures, are widely used. By llinking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned structures can be desinged. In this paper, a new algorithm for structural dynamic modification-SRFSM (substructure response function sensitivity method) is proposed by linking frequency responce function synthesis and response function sensitivity. A mehtod to obtain response function sensitivity using direct derivative of mechanical impedance, is also used.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.4
• /
• pp.38-43
• /
• 2011

Industrial reducer is in general use to Deck Crane. High-precision and high-efficient reducer is minimized the power-loss and energy-loss of a machine. So it contribute the price reduction and life extension. Reducer is usually using the Planetary gear reducer. Planetary gear reducer is composed the sun gear, planet gear, internal gear and casing. Industrial reducer's wear and breakage have a short-life. To solve this problem, it is using the profile-shifted-gear or tooth modification. This study was carried out the effect of addendum modification coefficient on tooth fillet bending strength to planetary reducer. Tooth fillet bending stress is calculate. And all parameter were expressed the function of addendum modification coefficient. And then stress concentration factor of tooth fillet curve was express the function of addendum modification coefficient using comparison between theory and finite element analysis.

• Bulletin of the Korean Mathematical Society
• /
• v.38 no.1
• /
• pp.29-53
• /
• 2001

This note presents a an indirect adaptive control scheme for first-order continuous-time systems. The estimated plant model is controllable and then the adaptive scheme is free from singularities. The singularities are avoided through a modification of the estimated plant parameter vector so that its associated Sylvester matrix is guaranteed to be nonsingular. That properties is achieved by ensuring that the absolute value of its determinant does not lie below a positive threshold. A modification scheme based on the achievement of a modified diagonally dominant Sylvester matrix of the parameter estimates is also given as an alternative method. This diagonal dominance is achieved through estimates modification as a way to guarantee the controllability of the modified estimated model when a controllability measure of the ‘a priori’ estimated model fails. In both schemes, the use of a hysteresis switching function for the modification of the estimates is not required to ensure the nonsingularity of the Sylvester matrix of the estimates.

• Journal of Korean Medicine for Obesity Research
• /
• v.4 no.1
• /
• pp.95-123
• /
• 2004

Objects: This study was aimed to find out correlation between life style and cardiopulmonary function and body fat. Methods: We divided two groups by the score of behavior modification therapy questionnaire. Westudied tendency of change of cardiopulmonary function and body fat for medication of Mahuang capsule by ergogenic aids and placebo with circuit training. We got the results for Exercise stress test and Segmental Bioelectrical Impedence Analysis. Results: 1. High Score Group in Behavior Modification Therapy Questionnaire significantly(p<.05) showed elevation of Lean Body Mass, Body Fat, Waist Circumference and not significantly elevation of Body Weight, But Basal Metabolic Rate was declined. Low Score Group in Behavior Modification Therapy Questionnaire significantly(p<.05) showed elevation of Waist Circumference and not significantly elevation of Body Weight and Body Fat, Lean Body Mass but decline of Basal Metabolic Rate, Waist to Hip Ratio 2. High Score Group in Behavior Modification Therapy Questionnaire significantly(p<.05) showed elevation of $VO_{2max}$ and not significantly elevation of the rest. Low Score Group in Behavior Modification Therapy Questionnaire significantly(p<.05) showed elevation of rest Heart Rate, Diastolic Blood Pressure, and not significantly elevation of the rest except for METs Conclusion: High score group in Behavior Modification Therapy Questionnaire showed significantly elevation of body composition, but had no relationship with Cardiopulmonary function