• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.232-235
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• 2008

The vibration of steam turbine is caused by Mass Unbalance, Shaft Misalignment, Oil Whip and Rubbing etc. but in turbine which is normally operated and maintained, the Mass Unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200MW and 135MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of No 3 and 4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of No 1 steam turbine. Until a recent date, No 3 and 4 bearings which support high pressure turbine for No 1 steam turbine had shown about 135${\mu}$m in vibration amplitude (sometimes it increased to 221${\mu}$m maximum. alarm: 6mils, trip: 9mils) at base load. After applying the study, they decreased to about 40${\mu}$m maximum. It is a result from that we did not change the setting value of Bearing Alignment and only changed the assembly position of internal parts in Synchro Clutch Coupling Rachet Wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl stopper surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, We researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and We got good result by applying the findings of this study.

• Earthquakes and Structures
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• v.7 no.5
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• pp.817-842
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• 2014

ASCE/SEI 41-13 provides modeling parameters and numerical acceptance criteria for various types of members that are useful for evaluating the seismic performance of reinforced concrete (RC) building structures. To accurately evaluate the global performance of a coupled wall system, it is crucial to first properly define the component behaviors (i.e., force-displacement relationships of shear walls and coupling beams). However, only a few studies have investigated on the modeling of RC coupling beams subjected to earthquake loading to date. The main objective of this study is to assess the reliability of ASCE 41-13 modeling parameters specified for RC coupling beams with various design details, based on a database compiling almost all coupling beam tests available worldwide. Several recently developed coupling beam models are also reviewed. Finally, a rational method is proposed for determining the chord yield rotation of RC coupling beams.

• Current Optics and Photonics
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• v.3 no.6
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• pp.502-509
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• 2019

Based on the typical pixel structure and parameters of a polysilicon uncooled bolometer, the absorption rate of a polysilicon microbridge infrared detector for 10.6 ㎛ laser energy was calculated through the optical admittance method, and the thermal coupling model of a polysilicon microbridge component irradiated by far infrared laser was established based on theoretical formulas. Then a numerical simulation study was carried out by means of finite element analysis for the actual working environment. It was found that the maximum temperature and maximum stress of the microbridge component are approximately exponentially changing with the laser power of the irradiation respectively and that they increase monotonically. The highest temperature zone of the model is gradually spread by the two corners of the bridge surface that are not connected to the bridge legs, and the maximum stress acts on both sides of the junction of the microbridge legs and the substrate. The mechanism of laser-induced hard damage to polysilicon detectors is the melting damage caused by high temperature. This paper lays the foundation for the subsequent study of the interference mechanism of the laser on working state polysilicon detectors.

• Journal of KIISE:Software and Applications
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• v.33 no.3
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• pp.301-315
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• 2006

In component-based system, the qualities of components as reusable units are the most important to success the component-based development. Therefore, before software implementation phase, the designed components should be measurable to improve the qualities of the components and the measured results should be reflected in the component-based development phase. In addition, the qualities of the components should be measured accurately. Accordingly, this paper proposes cohesion and coupling metrics applying static and dynamic dependency characteristics by the interdependence between classes. We prove the theoretical soundness of the proposed metrics by the axiom of briand et al. A case study and a comparison with the conventional metrics verify the practicality of the proposed metrics. The development times and endeavors to design the components is reduced, because the proposed metrics measure the qualities of components accurately.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1556-1560
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• 2012

A simple highly versatile and efficient method has been developed for the three-component coupling of aldehydes, amines and alkynes to prepare propargylamines, in the presence of a catalytic amount of $BiCl_3$. The advantages of methods are high yield, mild reaction conditions, no environmental pollution and easy work up procedure.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.1
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• pp.37-43
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• 2020

This paper presents analysis of passive metal interconnection of the LNA block in CMOS integrated circuit. The performance of circuit is affected by the geometry of RF signal path. To investigate the effect of interconnection lines, a cascode LNA is designed, and circuit simulations with full-wave electromagnetic (EM) simulations are executed for different positions of a component. As the results, the position of an external capacitor (C_ex) changes the parasitic capacitance of electric coupling; the placement of component affects the circuit performance. This analysis of interconnection line is helpful to analyze the amount of electromagnetic coupling between the lines, and useful to choose the signal path in the layout design. The target of this work is the RF LNA enabling the seamless connection of wireless data network and the following standards have to be supported in multi-band (WCDMA: 2.11~ 2.17 GHz, CDMA200 1x : 1.84~1.87 GHz, WiBro : 2.3~2.4GHz) mobile application. This work has been simulated and verified by Cadence spectre RF tool and Ansoft HFSS. And also, this work has been implemented in a 0.13um RF CMOS technology process.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.635-642
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• 1995

조립제품을 생산하기 위해, 부품간의 조립순서를 결정하는 문제는 전체조립공정에 중대한 영향을 미치는 문제이다. 이때 부품간이 조립순서를 결정하기 위해서는 조립상태에 관한 정보가 필요하다. 따라서 효율적인 조립순서를 결정하기 위해서는 조립상태에 대한 효과적인 표현법이 필요하게 된다. 본 논문에서는 이러한 효과적인 조립정보의 표현법으로서 CCG를 제시한다. CCG는 Component Coupling Graph로서 부품간의 기하학적인 간섭관계에 대한 정보를 접근 방향별로 표현한 그래프이다. 이때 접근방향은 +x,-x,+y,-y,+z,-z의 여섯방향이다. 이 CCG를 이용하면 각 조립상태에 대한 분해가능한 부품을 논리적으로 추론해 낼 수 있게 된다. 부품간의 기하학적인 간섭관계는 coupling 개념을 이용하여 표현하게 되는데, coupling은 각 부품간의 방향별 거리를 나타낸다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1366-1371
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• 2006

A structural coupling method is developed for the dynamic analysis of a nonlinear structure with concentrated nonlinear hinge joints or sliding lines. Component mode synthesis method is extended to couple substructures and the nonlinear models. In order to verify the improved coupling method, a numerical plate model consisting of two substructures and torsional springs, is synthesized by using the proposed method and its model parameters are compared with analysis data. Then the coupling method is applied to a three-substructure-model with the nonlinearity of sliding lines between the substructures. The coupled structural model is verified from its dynamic analysis. The analysis results show that the improved coupling method is adequate for the structural nonlinear analyses with the nonlinear hinge and sliding mode condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.674-680
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• 2005

The top spindle, end coupling and slipper metal are important components of the hot rolling process and are used for transmission of heavy rotational power. In this study, kinematic analysis is conducted using finite element method for hot rolling process under slipper metal combination types and operation situations. The structural analysis is performed by applying the combination type, rotational boundary condition of top spindle, end coupling and slipper metal. This study aims to minimize the mechanical problems which might happen in the production process.

• The Journal of Society for e-Business Studies
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• v.8 no.2
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• pp.113-129
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• 2003

Component-based software development (CBSD) has been recognized effective reuse techniques for software development by many of researchers and companies. The purpose of CBSD is to produce a high quality software system quickly through using verified software component which is contained fine-grained business logics. This paper suggests the metrics and techniques for to extract component and its interface from legacy object oriented application. For extract component, we apply metrics to measure complexity, cohesion and coupling to the legacy system.