• 한국가스학회지
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• 제10권2호
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• pp.55-60
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• 2006

Detailed modeling of PEMFCs has been getting considerable interest for predicting the fuel cell performance and also for use in various systems engineering activities. While CFD-based equipment models provide detailed analyses of the performance, they are very time-consuming to develop and run. The computations become quite complex when such models have to be embedded into the flowsheet-level optimization of fuel cell systems. In this paper, we present results about building and using NN-based reduced order models for quickly and repetitively predicting the flow of reactants in a PEMFC manifold.

• 산업공학
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• 제20권3호
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• pp.363-375
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• 2007

Under the fast technology changes and budget constraints, the organizations related to national defense face increased demands to develop innovative strategy and methodology to maximize performance with drastically reduced cost. In this context, the management of innovation and change in the defense acquisition area is vital to the Ministry of National Defense, related organizations and industries. In this paper, we discuss three comprehensive innovation strategies and methodologies for the defense acquisition area preparing for next-generation warfare; EVMS (earned value management system), PBL (performance based logistics) and SBA (simulation based acquisition). These collaborating innovative efforts enable us to tackle defense challenges for government and industries with a flexible and optimistic approach that maximizes productivity and performance with minimum cost.

• 기술혁신연구
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• 제15권1호
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• pp.27-63
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• 2007

Recently, Kim and Mauborgne (2005a) has introduced the concept of blue ocean strategy that provides quantum leap in value innovation, thus creating new market space. This study, based on the blue ocean strategy concept, suggests blue ocean new product development strategy, and attempts to examine how much impact this blue ocean new product development strategy has on new product performance, compared to existing new product development strategy perspectives based on competitive strategy-based new product development strategy and resource-based new product development strategy, in an empirical way. The research results show that the blue ocean new product development strategy has a statistically significant impact on new product performance. In addition, it was revealed that such contingency variables as firm size and environmental dynamism have moderating effect on the relationship between the blue ocean new product development strategy and new product performance. The blue ocean new product development strategy is more effective in the small-sized firms than the large-sized ones, and its effect on new product performance is different according to environmental dynamism.

• Structural Engineering and Mechanics
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• 제48권5호
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• pp.681-695
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• 2013

Performance-based seismic design allows a structure to develop inelastic response during earthquakes. This modern seismic design requires more clearly defined levels of inelastic response. The ultimate deformation of a structure without total collapse (target displacement) is used to obtain the inelastic deformation capacity (inelastic performance). The inelastic performance of a structure indicates its performance under excitation. In this study, a new energy-based method to obtain the target displacement for reinforced concrete frames under cyclic loading is proposed. Concrete structures were analyzed using nonlinear static (pushover) analysis and cyclic loading. Failure of structures under cyclic loading was controlled and the new method was tested to obtain target displacement. In this method, the capacity energy absorption of the structures for both pushover and cyclic analyses were considered to be equal. The results were compared with FEMA-356, which confirmed the accuracy of the proposed method.

• Wind and Structures
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• 제2권4호
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• pp.325-345
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• 1999

In recent years, rainscreen walls based on the pressure equalization principle are often used in building construction. To improve the understanding of the influence of several design parameters on the pressure equalization performance of such wall systems, a theoretical consideration of the problem may be more appropriate. On this basis, this paper presents two theoretical models, one based on mass balance and the other based on the Helmholtz resonator theory, for the prediction of cavity pressure in rigid rainscreen walls. New measures to assess the degree of pressure equalization of rainscreen walls are also suggested. The results show that the model based on mass balance is sufficiently accurate and efficient in predicting the cavity pressure variations. Further, the performance of the proposed model is evaluated utilizing the data obtained from full-scale tests and the results are discussed in detail.

• 대한전기학회논문지
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• 제41권2호
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• pp.144-155
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• 1992

A design of a highly stable current-controlled power supply combining the phase-controlled rectifier (PCR), passive filter and active filter is investigated. A digital phase-looked voltage control (PLVC) with a capability of compensating the thyristor firing angles under unvalanced power source is proposed` otherwise the PCR output voltage has low-order subharmonics whose suppression requires a bulky passive filter. The digital PLVC has a fast dynamic characteristics as an inner control loop of the PCR. To suppress further the output ripple, an active filter using a transformer is introduced and its design is described through the frequency domain analysis. An optimal integral, proportional and measurable variable feedback (IPM) controller is designed using the time-weighted performance index based on the time domain analysis. The design method based on the time-weighted performance index gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives good dynamic and static performances.

• 수산해양교육연구
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• 제27권1호
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• pp.108-114
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• 2015

The purpose of this study is to find the relationships among communication competency, social network centrality(trust centrality and knowledge sharing centrality), discussion performance, and online boarding activity in the team based learning situation. For investigating this topic, 44 students are participated in the classes of educational technology. In order to find out the relationships among communication competency, social network centrality, discussion performance, and online boarding activity, compared t-test and path analysis are used. Followings are the results of the research: (a) Communication competency is improved significantly after team based learning. (b) Trust centrality effects significantly on the knowledge sharing centrality. (c) Knowledge sharing effects significantly on discussion performance. (d) Trust centrality effects on the online boarding activity in the team based learning.

• 산업경영시스템학회지
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• 제23권57호
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• pp.11-20
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• 2000

In dynamic management environment, CEO must make an efficient decision with information & knowledge management systems based on IT(Information Technology). As a key component to cope with this current, we suggest the business performance analysis system based on KDD(Knowledge Discovery in Databases). We consider the theoretical model that is composited both Value-Added in respect of stakeholder and Economic Value-Added in respect of shareholder. Additionally we use DBMS and data mining method using Genetic Algorithms as physical model. To demonstrate the performance of the business performance analysis system, we analyse a domestic motors industry. The empirical case is based on the financial data of KISFAS(Korea Investors Services Financial Analysis System) database. The samples included in the study consist of H motors/S motors industry over the 16-year from 1981 to 1996.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.821-824
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• 2008

This paper presents a systematic approach for estimating material performance of concrete mixture design based on satisfaction curves developed from statistical evaluation of existing or newly obtained material property related data. In performance based material design (PBMD) method, concrete material used for construction of a structure is designed considering a structure's specified performance requirements based on its usage and characteristics such as environmental conditions, structure types, expected design life, etc.Satisfaction curves express the probabilities that one component of substrates (i.e., aggregate size, cement content, etc) of concrete mixture will sustain different criterion value for a given concrete mixture design. This study presents a statistical analysis method for setting up concrete material parameter versus concrete criterion relationships in the form of satisfaction curves and for estimating confidence bounds on these satisfaction curves. This paper also presents an analysis method to combine multiple satisfaction curves to form one unique satisfaction curve that can relate the performance of concrete to a single evaluating value. Based on several evaluated mixture design examples for various material properties, the validity of the proposed method is discussed in detail.

• 음성과학
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• 제15권2호
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• pp.79-88
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• 2008

Recently demands for the speech technology-based products targeted for the mobile terminals such as cellular phones and PDA are rapidly increasing. And voting-based speaker identification algorithm is known to have a good performance in the mobile environment, since it works well with small amount of speaker training data. In this paper, we proposed a method to improve the performance of this voting based speaker identification system by using the observation confidence value which is derived from the function of SNR each frame. The proposed method is evaluated with ETRI cellular phone DB which is made for the speaker recognition task. The experimental results show that the proposed method has better performance of 2-3% identification rate than the conventional GMM method.