• 산업공학
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• 제22권2호
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• pp.165-173
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• 2009

This paper considers a two-component assembly system that makes different types of purchasing contracts by component type and studies the issue of coordinating those contracts. Acquisition of type 1 component is based on the long-term contract. In contrast, type 2 component is intermittently purchased under the sort-term contract. We identify the structural properties of the optimal short-term contract and investigate how the changes in system parameters affect the optimal performance. To provide managerial insights, we compare the short-term and long-term contracts for type 2 component and discuss the conditions that make the short-term contract preferable to the long-term contract. We also present a result which shows that coordinating the contracts of type 1 and type 2 components can be significantly profitable over uncoordinating them.

• 한국추진공학회지
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• 제9권4호
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• pp.81-88
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• 2005

가스터번 엔진의 성능을 예측하기 위해서는 자신의 성능 특성을 포함한 구성품 성능도가 요구된다. 본 연구에서는 유전 알고리즘을 이용하여 압축기 성능도를 제작사에서 제공한 성능덱으로부터 역으로 식별하는 방법을 제안하였다. 알고리즘은 경사 로터 방식 스마트 UAV를 위한 PW206C 터보축 엔진에 적용하였다. 제안된 방법을 검증하기 위하여 새롭게 만들어진 압축기 성능도를 이용한 해석 결과와 제작사에서 제공한 EEPP(Estimated Engine Performance Program) 덱(deck)을 이용한 해석 결과를 비교하였다. 또한 기존의 스케일링 방법을 이용하여 얻어진 구성품 성능도를 이용한 해석결과와도 비교하였다. 그 결과 운용 영역이 설계점에서 멀어질수록 기존의 스케일링 방법을 이용한 구성품 성능도를 사용한 경우 오차가 크게 증가하였다. 반면 유전알고리즘을 이용하여 생성된 압축기 성능도를 사용한 경우 EEPP의 해석결과에 더 근접함을 확인할 수 있었다.

• Journal of the Korean Statistical Society
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• 제29권1호
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• pp.63-80
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• 2000

We consider the panel data regression model with nested error componets. In this paper, the several Lagrange Multipler tests for the nested error component model are derived. These tests extend the earlier work of Honda(1985), Moulton and Randolph(1989), Baltagi, et al.(1992) and King and Wu(1997) to the nested error component case. Monte Carlo experiments are conducted to study the performance of these LM tests.

• 한국전자거래학회:학술대회논문집
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• 한국전자거래학회 1999년도 학술대회지 vol.2
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• pp.431-445
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• 1999

This paper introduces a development of component based framework of supply-chain management. The existing legacy system, which is not designed for object-oriented paradigm, is re-modeled using unified modeling language. Components are extracted from the legacy application, and frameworks are also designed in order to increase productivities of software development. Design issues concerning component and framework development are discussed with real situation. Performance and development productivity issue are also discussed with discussing component size and scope. A real case is presented in connection with the discussed issues.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.409-410
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• 2006

New applications for PM have resulted in a substantial market growth during the last decades. The clue to these components lies in the utilization of new powders and component production processes. In order to reduce development time and increase the probability for success it is essential to work in close cooperation within the whole chain from powder supplier to component supplier and component user.

• Earthquakes and Structures
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• 제15권6호
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• pp.583-593
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• 2018

Seismic performance is particularly important for life-line structures, especially for long-span transmission tower line system subjected to multi-component ground motions. However, the influence of multi-component seismic loads and the coupling effect between supporting towers and transmission lines are not taken into consideration in the current seismic design specifications. In this research, shake table tests are conducted to investigate the performance of long-span transmission tower-line system under multi-component seismic excitations. For reproducing the genuine structural responses, the reduced-scale experimental model of the prototype is designed and constructed based on the Buckingham's theorem. And three commonly used seismic records are selected as the input ground motions according to the site soil condition of supporting towers. In order to compare the experimental results, the dynamic responses of transmission tower-line system subjected to single-component and two-component ground motions are also studied using shake table tests. Furthermore, an empirical model is proposed to evaluate the acceleration and member stress responses of transmission tower-line system subjected to multi-component ground motions. The results demonstrate that the ground motions with multi-components can amplify the dynamic response of transmission tower-line system, and transmission lines have a significant influence on the structural response and should not be neglected in seismic analysis. The experimental results can provide a reference for the seismic design and analysis of long-span transmission tower-line system subjected to multi-component ground motions.

• 한국전자통신학회논문지
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• 제9권4호
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• pp.439-446
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• 2014

본 연구는 디지털위성중계기의 우주인증 모델에 대한 성능분석 및 구현에 대해 기술하였다. 사전 성능 분석은 각 구성품 회로 시뮬레이션을 통해 각 구성품에 대한 요구 규격 대비 만족 여부를 사전 검증하고, 각각의 구성품을 순서대로 연결하여 전체적인 디지털위성중계기의 요구 규격에 만족하는지를 사전 검증하였다. 사전 시스템 성능 분석을 통하여, 각 구성품의 요구 규격을 정의하고, 그 규격을 바탕으로 제작하였으며, 최종적으로 시스템 통합하여 전체적인 디지털위성중계기의 성능 측정을 하였다.

• 대한원격탐사학회지
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• 제33권4호
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• pp.445-454
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• 2017

The performance of spatial downscaling models depends on the quality of input coarse scale products. Thus, the impact of intrinsic errors contained in coarse scale satellite products on predictive performance should be properly assessed in parallel with the development of advanced downscaling models. Such an assessment is the main objective of this paper. Based on a synthetic satellite precipitation product at a coarse scale generated from rain gauge data, two synthetic precipitation products with different amounts of error were generated and used as inputs for spatial downscaling. Geographically weighted regression, which typically has very high explanatory power, was selected as the trend component estimation model, and area-to-point kriging was applied for residual correction in the spatial downscaling experiment. When errors in the coarse scale product were greater, the trend component estimates were much more susceptible to errors. But residual correction could reduce the impact of the erroneous trend component estimates, which improved the predictive performance. However, residual correction could not improve predictive performance significantly when substantial errors were contained in the input coarse scale data. Therefore, the development of advanced spatial downscaling models should be focused on correction of intrinsic errors in the coarse scale satellite product if a priori error information could be available, rather than on the application of advanced regression models with high explanatory power.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.136-145
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• 2013

It is very important to determine specifications of components included in the drive-train of vehicles at the initial design stage. In this study, component sizing process and performance analysis for Extended-Range Electric Vehicles (E-REV) are discussed based on the foundation of determined system configuration and performance target. This process shows sizing results of an electric driving motor, a final drive gear ratio and a battery capacity for target performance including All Electric Range (AER) limit. For E-REV driving mode, the constant output power of a Gen-set (Engine+Generator) is analyzed in order to sustain State of Charge (SOC) of the battery system.

• 한국신뢰성학회지:신뢰성응용연구
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• 제10권1호
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• pp.1-9
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• 2010

In general, the performance of a component degrades as time goes by and failure of a component occurs when the performance degradation reaches a pre-specified level. It is difficult to obtain the failure time distribution data or the necessary number of failure data especially for the metal or machine part. Thus, a design of reliability qualification test based on performance distribution is more effective than failure time distribution. In this study, a performance-based reliability qualification test is developed and a numerical example is provided to illustrate the use of the developed reliability qualification test. This approach could be applied to many kinds of metal or machine part whose magnitude of strength could not be evaluated during at any random points but judgement can be made by only failure of the part. Besides, it is also possible that any parts which have a similar failure characteristics could be applicable to the developed reliability qualification test.