• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.823-827
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• 2008

The effects of blade leading edge sweep on both the aerodynamic performance and the structure stress of a high pressure centrifugal compressor impeller are numerically investigated. Changes in the flow structure occur as a result of the effect of leading edge sweep on the loading distribution in the tip region. The flow separation is avoided by introducing a sweep of the main blade leading edge and the strength of shock is reduced at the same time. Backswept of the leading edge is found to be beneficial to the impeller performance improving. On the other hand, the structural analysis indicated that high rotating speed of the impeller will cause substantial high bending stresses and radial deflections of the blade. Studies have shown that it is possible to control the stress distribution along the tip and root of the blade by slight adjustments to the sweep angle of the leading edge. These adjustments may be used to design the impeller with lower blade root stress distribution without aerodynamics performance penalty.

• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.115-123
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• 2021

Through machine learning-based load prediction, it is possible to prevent excessive power generation or unnecessary economic investment by estimating the appropriate amount of facility investment in consideration of the load that will increase in the future or providing basic data for policy establishment to distribute the maximum load. However, in order to secure the reliability of the developed load prediction model in the field, the performance comparison verification between the distribution line load prediction models must be preceded, but a comparative performance verification system between the distribution line load prediction models has not yet been established. As a result, it is not possible to accurately determine the performance excellence of the load prediction model because it is not possible to easily determine the likelihood between the load prediction models. In this paper, we developed a reliability verification system for load prediction models including a method of comparing and verifying the performance reliability between machine learning-based load prediction models that were not previously considered, verification process, and verification result visualization methods. Through the developed load prediction model reliability verification system, the objectivity of the load prediction model performance verification can be improved, and the field application utilization of an excellent load prediction model can be increased.

• 유통과학연구
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• 제21권12호
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• pp.91-102
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• 2023

Purpose: This study analyzed the structural relationship between interaction quality and relationship satisfaction, towards providing managerial implications for effective relationship management in the B2B market. Research design, data and methodology: The following survey was conducted only if respondents had used the airline's B2C more than twice. A total of 398 copies were collected and empirical analysis was conducted using AMOS 18.0 and PASW 18.0. Results: The flexibility, quickness, and fairness that make up the interaction quality in airline B2C have been shown to have a significant impact on trust, relationship performance and relationship satisfaction. Conclusions: Usefulness, quickness, and fairness, which are sub-variables of airline B2C mutual quality, have a positive effect on trust. In addition, trust was found to have a positive effect on relationship performance and relationship satisfaction. We draw implications for the importance of interaction quality in order to strengthen and sustain relationships with users in the airline B2C distribution market. In addition, in order to build meaningful relationship performance and relationship satisfaction, interaction quality and trust level should be examined first, and interaction quality improvement should be the top goal.

• 유통과학연구
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• 제22권1호
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• pp.105-113
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• 2024

Purpose: This study sheds light on the need for trust in buyer-seller relationships in supply chains and explores why long-term orientation is important. It also investigates the effect on relationship performance. This study provides implication on how to build robust supply chains. Methodology: A survey was conducted with firms with supply chains in South Korea. A total of 350 valid questionnaires were analyzed through Entrust Survey-a sampling company. Structural equation modeling (SPSS 18.0 and AMOS) was employed to test the hypotheses. Results: Cognitive trust had a positive effect on emotional trust. Emotional trust had a positive effect on long-term orientation but did not have a significant effect on relationship performance. Long-term orientation was proportionate to relationship performance. Conclusions: Trust is a critical factor in supply chains. As business environments are rapidly changing, the uncertainties are also meaningful. Supply chains have collapsed owing to COVID-19, the Russia-Ukraine war, and the U.S.-China trade war, and they are only just recently being rebuilt. Maintaining relationships with supply-chain partners is vital, and promoting cognitive and emotional trust is necessary.

• 유통과학연구
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• 제22권3호
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• pp.113-124
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• 2024

Purpose: This study is a quantitative study and analyzes the effect of evaluating the extreme and usefulness of product reviews on sales performance by using text mining techniques based on product review big data. We investigate whether the perceived helpfulness of product reviews serves as a mediating factor in the impact of product review extremity on sales performance. Research design, data and methodology: The analysis emphasizes customer interaction factors associated with both product review helpfulness and sales performance. Out of the 8.26 million Amazon product reviews in the book category collected by He & McAuley (2016), text mining using natural language processing methodology was performed on 300,000 product reviews, and the hypothesis was verified through hierarchical regression analysis. Results: The extremity of product reviews exhibited a negative impact on the evaluation of helpfulness. And the helpfulness played a mediating role between the extremity of product reviews and sales performance. Conclusion: Increased inclusion of extreme content in the product review's text correlates with a diminished evaluation of helpfulness. The evaluation of helpfulness exerts a negative mediating effect on sales performance. This study offers empirical insights for digital market distributors and sellers, contributing to the research field related to product reviews based on review ratings.

• 한국정보처리학회논문지
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• 제3권6호
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• pp.1433-1442
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• 1996

자료 분산은 SPMD(Single Program Multiple Data)형태의 병렬성을 제공하는 HPF (High Performance Fortran)의 주기능으로 구현 방법에 따라 컴파일러 성능을 좌우한 다. 본 논문에서는 SPAX(Scalable Parallel Architecture computer based on X-bar network)상에 자료 분산 기능을 제공하기 위한 설계 주안점과 효율적인 모델에 관하 여 기술하였다. SPAX는 분산공유 메모리 (DSM:distributed shared memory)를 사용한 계층적 클러스터링 구조를 가진다. 이러한 메모리 구조에서는 분산 메모리 자료 분산 (DMDD:Distributed Memory Data Distribution)이나 공유 메모리 자료 분산(SMDD: Shared Memory Data Distribution)방법으로는 시스템 가용성을 만족할 수 없다. 그래 서 계층적 마스터-슬래브 형태의 분산공유 메모리 자료분산(DSMDD:Distributed Shared Memory Data Distribution)모델을 설계하였다. 이 모델은 각 노드에 원격 마 스터와 슬래브들을 할당하고 노드내에서는 공유 메모리를 그리고 노드간에는 메세지 전달 인터페이스를 사용한다. 시뮬레이션을 수행한 결과, 시스템 성능 저하를 최소화 하는 노드 크기로 DSMDD를 수행하였을 때 SMDD나 DMDD보다 훨씬 더 효율적이였다. 특 히, 논리적 프로세서 갯수가 많을수록, 분산된 자료들 간의 자료 종속성이 적을수록 성능이 우수하였다.

• 품질경영학회지
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• 제38권2호
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• pp.171-179
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• 2010

Pearn et al.(2002) supposed the $C_{pp}$ multiple process performance analysis chart. This chart displays multiple processes with the process variation and process departure on one single chart. But, this chart can not display the distribution of the process variation and process departure and is inappropriate for processes with non-normal distributions. With bootstrapping method, we can display the distribution of the process variation and process departure on the $C_{pp}$ multiple process performance analysis chart.

• 한국유통학회지:유통연구
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• 제1권1호
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• pp.109-127
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• 1996

The purpose of this study was to represent hypotheses of the interrelationship of the level of cooperation, conflict, and performance and to report the findings testing the hypotheses in car channels. This study provides some general guidance toward better cooperation, conflict, and performance management. The results indicate that noncoercive bases of power and dependence hale a positive effect on cooperation, while the proposed inverse relationship between coercive bases of power and cooperation is not statistically significant. Coercive bases of power have a positive effect on conflict, while conflict is not statistically significant for noncoercive bases of power, dependence, and cooperation. Finally, cooperation has a positive effect on dealer performance, but conflict has a negative effect on dealer performance.

• 상하수도학회지
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• 제24권5호
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• pp.509-517
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• 2010

Statistical distribution of annual maximum rainfall intensity of 18 cities in Korea was analyzed and applied to the reliability model which can calculate the probability of performance failure of storm sewer. After the analysis, it was found that distribution of annual maximum rainfall intensity of 18 cities in Korea is well matched with Gumbel distribution. Rational equation was used to estimate the load and Manning's equation was used to estimate the capacity in reliability function to calculate the probability of performance failure of storm sewer. Reliability analysis was performed by developed model applying to the real storm sewer. It was found that probability of performance failure is abruptly increased if the diameter is smaller than certain size. Therefore, cleaning the inside of storm sewer to maintain the original diameter can be one of the best ways to reduce the probability of performance failure. In the present study, probability of performance failure according to accumulation of debris in storm sewer was calculated. It was found that increasing the amount of debris seriously decrease the capacity of storm sewer and significantly increase the probability of performance failure.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.132-151
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• 2024

Proton exchange membrane fuel cell (PEMFC) has received extensive attention as it is the most common hydrogen energy utilization device. This research not only investigated the effect of obstacle number and shape on PEMFC performance, but also studied the effect of the blockage degree in the channel of PEMFC on its performance. It was found that compared with traditional scheme, longitudinally distributed obstacles scheme can significantly promote reactants transfer to catalyst layer, and the blockage degree in the channel effect PEMFC performance most. The scheme with 10 rectangular obstacles in single channel and 60% channel blockage had the best output performance and the most uniform distribution of reactants and products. Obstacle height distribution can significantly affect PEMFC performance, the blockage degree in the whole basin was large, particularly as the channel was blocked to higher degree in region 2 and region 3, higher net power density and better mass transfer effect can be obtained. Among them, the fuel cell with the blockage degree of 40%, 60% and 60% in region 1, region 2 and region 3 have the best PEMFC output performance and mass transfer, the net power density was 29.8% higher than that of traditional scheme.