• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4726-4731
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• 2011

This paper proposed the algorithm to select optimal grinding condition for plunge grinding in the batch production unit. In order to apply to the proposed algorithm, the state variable for plunge grinding process was defined and the optimal grinding condition for each cycle in batch production was decided by genetic algorithm. Based on the optimized grinding condition in each cycle, the optimal grinding condition for whole batch production was selected by dynamic programming. The proposed algorithm was evaluated by computer simulation.

• Asia-Pacific Journal of Business
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• v.14 no.3
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• pp.221-240
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• 2023

Purpose - This paper investigates how business cycle impacts on corporate credit spreads since global financial crisis. Furthermore, it tests how the impact changes by the phase of the cycle. Design/methodology/approach - This study collected dataset from Barclays Global Aggregate Bond Index through the Bloomberg. It conducted multi-regression analysis by projecting business cycle using Hodrick-Prescott filtering and various cyclical variables, while ran dynamic analysis of 5-variable Vector Error Correction Model to confirm the robustness of the test. Findings - First, it proves to be statistically significant that corporate credit spreads have moved countercyclicaly since the crisis. Second, It indicates that the corporate credit spread's countercyclicality to the macroeconomic changes works symmetrically by the phase of the cycle. Third, the VECM supports that business cycle's impact on the spreads maintains more sustainably than other explanatory variable does in the model. Research implications or Originality - It becomes more appealing to accurately measure the real economic impact on corporate credit spreads as the interaction between credit and business cycle deepens. The economic impact on the spreads works symmetrically by boom and bust, which implies that the market stress could impact as another negative driver during the bust. Finally, the business cycle's sustainable impact on the spreads supports the fact that the economic recovery is the key driver for the resilience of credit cycle.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.199-199
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• 1991

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.305-307
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• 2005

• Corrosion Science and Technology
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• v.15 no.1
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• pp.18-27
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• 2016

In this study, the accelerated corrosion test by combined deteriorating action of salt damage and freeze-thaw was investigated. freeze-thaw cycle is one method for corrosion testing; corrosion initiation time was measured in four types of concrete samples, i.e., two samples mixed with fly ash (FA) and blast furnace slag (BS), and the other two samples having two water/cement ratio (W/C = 0.6, 0.35) without admixture (OPC60 and OPC35). The corrosion of rebar embedded in concrete occurred most quickly at the $30^{th}$ freeze-thaw cycle. Moreover, a corrosion monitoring method with a half-cell potential measurement and relative dynamic elastic modulus derived from resonant frequency measures was conducted simultaneously. The results indicated that the corrosion of rebar occurred when the relative dynamic elastic modulus was less than 60%. Therefore, dynamic elastic modulus can be used to detect corrosion of steel bar. The results of the accelerated corrosion test exhibited significant difference according to corrosion periods combined with each test condition. Consequently, the OPC60 showed the lowest corrosion resistance among the samples.

• Composites Research
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• v.20 no.1
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• pp.8-14
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• 2007

Nonlinear aeroelastic analyses of composite wing with flap are performed considering free-play and dynamic stiffness of actuator. Doublet-Hybrid method is used for the calculation of subsonic unsteady aerodynamic forces. Free-play is modeled as a bilinear spring and is linearized by using the describing function method. Dynamic stiffness is obtained from governing equation of gear system and the aeroelastic analyses were performed according to ply-angle of laminate and material. The linear and nonlinear flutter analysis results show that the flutter characteristics are significantly dependent on the free-play and dynamic stiffness. from the nonlinear flutter analysis, various types of limit cycle oscillations are observed in a range of air speeds below or above the linear divergent flutter boundary.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.1
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• pp.16-21
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• 2002

In this paper, a dual type PFD(Phase Frequency Detector) for high speed PLL to improve output characteristics using TSPC(True Single Phase Clocking) circuit is proposed. The conventional 3-state PFD has problems with large dead-zone and long delay time. Therefore, it is not applicable to high-speed PLL(Phase-Locked Loop). A dynamic PFD with dynamic CMOS logic circuit is proposed to improve these problems. But, it has the disadvantage of jitter noise due to the variation of the duty cycle. In order to solve the problems of previous PFD, the proposed PFD improves not only the dead zone and duty cycle but also jitter noise and response characteristics by the TSPC circuit and dual structured PFD circuit. The PFD is consists of a P-PFD(Positive edge triggered PFD) and a N-PFD(Negative edge triggered PFD) and improves response characteristics to increase PFD gain. The Hspice simulation is performed to evaluate the performance of proposed PFD. From the experimental results, it has the better dead zone, duty cycle and response characteristics than conventional PFDs.

• Journal of Korean Society of Transportation
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• v.18 no.2
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• pp.73-89
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• 2000

This Paper documents the development of a cycle free based, coordinated dynamic signal timing model for minimizing queue lengths using Genetic A1gorithm. The model was embodied using MAT-LAB, the language of technical computing. A special feature of this model is its ability to manage queue lengths of turning movements at the start of green times. The model produces a cycle-free based signal timing(cycles and green times) for each intersection to minimize queue lengths of turning movements on the cycle basis. Concurrently, appropriate offsets could be accomplished by applying cycle-free based signal timings for respective intersections. The model was applied to an example network which consists of three intersections. The result shows that the model produces superior signal timings to the existing signal timing model in terms of managing queue lengths of turning movements.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1045-1049
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• 2005

In this paper, the dynamic crawling of a five-bar planar mechanism is investigated. One complete cycle of the crawling selected in this study consists of four different steps, i) sliding at one contact point between the mechanism and the ground, ii) changing its configuration without sliding at two contact points, iii) sliding at the other contact point, and iv) again changing its configuration without sliding at two contact points. In this type of crawling, the crawling mechanism maintains the shape of the parallel structure throughout a complete crawling cycle. The modeling algorithm for serial manipulators proposed by M. Thomas and et al.[1] is employed by introducing imaginary joints and links which represent the contact interfaces between the one end of the mechanism and the ground, while the other end of the mechanism is regarded as an end-effector of the imaginary serial manipulator which treats the reaction force and torque at the contact point as external forces. Then, a complete cycle of dynamic crawling of the mechanism is investigated through various computer simulations. The simulation result show that the stable crawling characteristics of the mechanism could be secured when the proper configurations depending on specified frictional constraints are met.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.37-46
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• 2004

This study was performed to establish valid methodology for determining dynamic stability(DS) of deformation-cycle curve which is obtained through wheel tracking(WT) test, the most widely used method for forecast of rutting tendency of asphalt mixture. Existing Korean and Japanese methods for DS are unrealistic and do not really reflect characteristics of rut resistance of asphalt concretes especially when the slope of deformation-cycle curve is stabilized at the end. It was proved that the new DS developed in this study reflected rut resistance characteristics better than existing methods. It is especially effective to distinguish the mixtures with high DR(depth of rut) but stable slope at the end of curve from the mixture with lower DR and continuous slope. The field evaluation must be followed to prove whether the mixture which shows a high DS value this method perform well in the filed.