• Proceedings of the KWS Conference
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• 2006.10a
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• pp.125-127
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• 2006

A spacer grid assembly, which is an interconnected array of slotted grid straps and is welded at the intersections to form an egg crate structure, is one of the main structural components of the nuclear fuel assembly for pressurized water reactors(PWRs). The spacer grid assembly is structurally required to have enough buckling strength under various kinds of lateral loads acting on the nuclear fuel assembly so as to keep the nuclear fuel assembly straight. To meet this requirement, it is necessary to weld the welding parts carefully and precisely. In this study, weld qualities such as, weld bead size, penetration, spatter, etc. manufactured by various welders were compared and analyzed. Comparison results show that the weld qualities could be improved by selecting the optimal welding condition and also improving the welding technique.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.565-576
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• 1997

The material-based homogenization design method generates arbitrary topologies of initial structural design as well as reinforcement structural design by controlling the amount of material available. However, if a small volume constraint is specified in the design of Lightweight structures, thin and slender structures are usually obtained. For these structures stability becomes one of the most important requirements. Thus, to prevent overall buckling (that is, to increase stability), the objective of the design is to maximize the buckling load of a structure. In this paper, the buckling analysis is restricted to the linear buckling behavior of a structure. The global stability requirement is defined as a stiffness constraint, and determined by solving the eigenvalue problem. The optimality conditions to update the design variables are derived based on the sequential convex approximation method and the dual method. Illustrated examples are presented to validate the feasibility of this method in the design of structures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.263-271
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• 2004

In this paper, we proposed a new buffer management algorithm using perVC-Queuing discipline. Proposed algorithm uses service rate estimation and assigns dynamic perVC threshold to each VCs. Service rate estimation and dynamic perVC threshold combined with global threshold provide nearly optimal throughput and improve fairness performance of network resource among GFR VCs as well as guarantee MCR of all VCs. From simulation results, we demonstrate the proposed scheme fulfills the requirement of GFR service as well as improves the TCP throughput.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.4
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• pp.48-53
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• 2005

This research is materialized the mechanism of a interlocking elevator device to meet with customer's requirement demanding a variety of function. On this suitably theoretical translation and by considering of material significance of the most factor's tension spring and torsion spring, it's compared and reviewed the stress's calculation according that SWC and SWPB applied differently. And also that is approved through actual experiment. Out of a variety of feasible movement. Torque Balance is materialized by combination of tension spring, torsion spring and disk spring. So that application of 3 factors for optimal design is very important factor. In future, this research thesis make sure to play a highly role for application and improvement mechanically in various industry sector out of materializing interlock.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.165-171
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• 2004

Smart UAV, which adopting tiltrotor aircraft concept, requires long endurance and high speed capability simultaneously These two contradictable flight performances are hard to meet with single wing concept and inevitably require the operation of flap system which should reveal optimal performance for each flight mode. In order to design SUAV flaperon satisfying the performance requirement, various configurations are generated and their aerodynamic performances are analyzed using numerical flow computations around flaps. Considering aerodynamic performance and manufacturing simplicity, a final flap configuration is selected.

• ETRI Journal
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• v.20 no.4
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• pp.301-326
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• 1998

In this paper, we have modeled and evaluated a new parallel processing system called Scalable Parallel computer Architecture based on Xbar (SPAX) for commercial applications. SMP systems are widely used as servers for commercial applications; however, they have very limited scalability. SPAX cost-effectively overcomes the SMP limitation by providing both scalability and application portability. To investigate whether the new architecture satisfies the requirements of commercial applications, we have built a system model and a workload model. The results of the simulation study show that the I/O subsystem becomes the major bottleneck. We found that SPAX can still meet the I/O requirement of the OLTP workload as it supports flexible I/O subsystem. We also investigated what will be the next most important bottleneck in SPAX and how to remove it. We found that the newly developed system network called Xcent-Net will not be a bottleneck in the I/O data path. We also show the optimal configuration that is to be considered for system tuning.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.727-732
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• 2000

This paper is on the development of a auxiliary power supply for the coach of Indian Railways. The auxiliary power supply system supplies the power for air-conditioners, air-compressors, lighting equipments, controllers, etc. It converts the input voltage, DC 110V which is supplied from battery, to AC 3${\Phi}$ 415V of 30kVA capacity. This is a low voltage-high current type converter system and largely consists of boost chopper and 3 phase inverter. Adopting a optimal control algorithm and simple power circuit, we realized the more reliable and competitive system for satisfaction of Indian Railway's strict requirement for vibration, temperature and dust. We completed the design, the manufacture and the field test of the system successfully and proved the system performance and reliability as a result of those tests.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.499-508
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• 2008

Frequency regulation in off-normal conditions has been an important problem in electric power system design/operation and is becoming much more significant today due to the increasing size, changing structure and complexity of interconnected power systems. Increasing economic pressures for power system efficiency and reliability have led to a requirement for maintaining power system frequency closer to nominal value. This paper presents a decentralized frequency control framework using a modified low-order frequency response model containing a proportional-integral(PI) controller. The proposed framework is suitable for near-normal and emergency operating conditions. An $H_{\infty}$ control technique is applied to achieve optimal PI parameters, and an analytic approach is used to analyse the system frequency response for wide area operating conditions. Time-domain simulations with a multi-area power system example show that the simulated results agree with those predicted analytically.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.511-512
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• 2015

최근 냉방장치의 사용증가로 전력수요가 크게 증가하고 있고, 이로 인해 전력수급 문제가 야기되고 있다. 이를 해결하기 위하여 여러 조치를 취하고 있지만 사실상 아직까지도 미흡한 실정이다. 최근에는 스마트 그리드의 구축이 진행 중이며, 스마트 그리드의 일환으로 실시간 요금제의 도입도 고려되고 있다. 따라서 부하제어 등의 수요관리를 통한 적절한 대처가 필요하다. 하지만 부적절한 부하제어는 사용자의 만족도를 해칠 우려가 있다. 이에 본 논문에서는 거주자의 쾌적도를 해치지 않는 조건에서 수용가에게 전기요금절감을 유도하는 냉방 시스템의 최적 부하제어 방법을 제안하는 바이다.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1212-1216
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• 2014

This study aims to find out the best anode location for buried pipelines. Numerical simulation program known as CATPRO (Elsyca, Belgium) were used for confirming the best location of anodes and the effects of impressed current cathodic protection system. Applied conditions for numerical simulation were similar to on-site environmental conditions for optimal application of cathodic protection system. Used criterion of cathodic protection was NACE SP 0169, which describes that minimum requirement for cathodic protection is -850mV vs. CSE. Various layouts for anodes' installation were applied, which were distance between anodes, anode installation location, and applied current. The areas where cathodic protection potential was lower than -850mV vs. CSE was limited up to 50m from anode installation locations. It was founded numerical analysis obtain cost-effective and efficient cathodic protection methods before design and application the impressed cathodic protection system to on-site environment.