• 한국산학기술학회논문지
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• 제20권7호
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• pp.347-352
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• 2019

본 연구는 소형 유도전동기 회전자를 생산공장에서 금형주조(die casting)로 제작 시 발생하는 cast 부 품질문제를 개선하기 위하여 수행되었다. 1차 연구결과와 현장 적용성을 고려한 수많은 parametric study를 통하여 새로운 rotor core cast model을 제안하였으며, 그 제안된 model에 대한 유효성을 평가, 검증하기 위하여 주조해석 전용프로그램을 사용한 수치해석과 실제품에 대한 현장실험을 통하여 다음과 같은 결론을 얻었다. 첫째, 유도전동기 회전자의 새로운 cast model에 대한 충진해석을 수행한 결과 용탕은 하부 end ring 부를 먼저 충진하고 이동하여 상부 end ring, core slot 부분을 충진하고 최종적으로 core slot 부분에서 충진이 완료된다. 둘째, 새롭게 제안된 rotor core cast model에 대한 용탕의 유동 양상을 보면 하부 end ring 부에 용탕의 유동에 의한 와류가 적게 발생하였으며, 현장실험 결과 하부 end ring 부 단면에서 소량의 작은 결함만이 발견되었다. 셋째, 유도전동기 회전자 제작 시 rotor core cast 형상 변경을 통하여 end ring 부 결함 발생 면적이 약 70 % 감소한 양호한 품질의 회전자를 생산할 수 있다.

• IEIE Transactions on Smart Processing and Computing
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• 제5권1호
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• pp.43-48
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• 2016

We propose plain fingerprint classification based on a core stochastic algorithm that effectively uses a core stochastic model, acquiring more fingerprint minutiae and direction, in order to increase matching performance. The proposed core stochastic algorithm uses core presence/absence and contains a ridge direction and distribution map. Simulations show that the fingerprint classification accuracy is improved by more than 14%, on average, compared to other algorithms.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.96-101
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• 2004

Core competence of enterprises became the focus of many researches recently. This essay summarizes the situation of Chinese harbor enterprises and establishes an evaluating model which makes use of factor-analysis.

• 한국기계가공학회지
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• 제20권9호
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• pp.11-19
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• 2021

Linear variable differential transformer (LVDT) is a displacement sensor and is commonly used owing to its wide measurement range, excellent linearity, high sensitivity, and precision. To improve the output characteristics of LVDT, a few studies have been conducted to analyze the output using a theoretical method or a finite element method. However, the material properties of the core and the electromagnetic force acting on the core were not considered in the previous studies. In this study, a finite element analysis model was proposed considering the characteristics of the LVDT composed of coils, core, magnetic shell and electric circuit, and the core displacement. Using the proposed model, changes in sensitivity and linear region of LVDT according to changes in process and material parameters were analyzed. The outputs of the LVDT model were compared with those of the theoretical analysis, and then, the proposed analysis model was validated. When the electrical conductivity of the core was high and the relative magnetic permeability was low, the decrease in sensitivity was large. Additionally, an increase in the frequency of the power led to further decrease in sensitivity. The electromagnetic force applied on the core increased as the voltage increased, the frequency decreased, and the core displacement increased.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.167-170
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• 2003

In this paper, a design and experiment of PCI Express Core verification Model is described. The model targeting Endpoint core verification is designed by using newly-emerging SystemC which is a system design language based on a new C++ class library and simulation engine. In the verification model, we developed a SystemC Host System model which act as a Root Complex and Device Driver dedicated to the PCI Express Endpoint RTL Core. The test of Host System Model is guided by scenarios which implements and acts point of Device Driver and Root Complex and shows the result of simulation. Also, We present the full structure of verification model and Host model.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.285-288
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• 2004

In this paper, we present a design and experiment of PCI Express core verification model. The model targeting Endpoint core based on Verilog HDL is designed by newly-emerging SystemC, which is a new C++ class library based system design approach. In the verification model, we designed and implemented a SystemC host system model which acted as Root Complex and device driver dedicated to the PCI Express Endpoint RTL core. The verification process is scheduled by scenarios which are implemented in host model. We show that the model is useful especially for verifying the RTL model which has dependencies on system software.

• BMB Reports
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• 제37권6호
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• pp.648-656
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• 2004

This paper deals with the development of a predictive probabilistic model, a composite dependency-reflecting model (CDRM), which was designed to detect core promoter regions and transcription start sites (TSS) in vertebrate genomic DNA sequences, an issue of some importance for genome annotation. The model actually represents a combination of first-, second-, third- and much higher order or long-range dependencies obtained using the expanded maximal dependency decomposition (EMDD) procedure, which iteratively decomposes data sets into subsets on the basis of dependency degree and patterns inherent in the target promoter region to be modeled. In addition, decomposed subsets are modeled by using a first-order Markov model, allowing the predictive model to reflect dependency between adjacent positions explicitly. In this way, the CDRM allows for potentially complex dependencies between positions in the core promoter region. Such complex dependencies may be closely related to the biological and structural contexts since promoter elements are present in various combinations separated by various distances in the sequence. Thus, CDRM may be appropriate for recognizing core promoter regions and TSSs in vertebrate genomic contig. To demonstrate the effectiveness of our algorithm, we tested it using standardized data and real core promoters, and compared it with some current representative promoter-finding algorithms. The developed algorithm showed better accuracy in terms of specificity and sensitivity than the promoter-finding ones used in performance comparison.

• Journal of the korean society of oceanography
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• 제38권2호
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• pp.45-51
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• 2003

Recent observations reveal that the Tsushima Current has a double-cored structure downstream of the Tsushima Island. To explain this, a simple analytical model is proposed based on the assumption of small lateral eddy viscosity. This model suggests that an otherwise uniform current becomes to have a stream core immediately after it enters a channel due to the action of lateral friction. The core is initially broad but becomes sharper downstream. The speed at which the core develops depends on the intensity of lateral eddy viscosity. Likewise, a single-cored stream changes rapidly to a double-cored stream when it passes through an island located in the center of the channel. When the stream leaves the island behind, the reverse process from the double-to single-cored structures takes place. In this case, however, the double-cored structure is retained for a significant distance from the island. Overall, this model suggests that the double-cored structure of the Tsushima Current observed downstream of the Tsushima Island Is created by the lateral friction exerted by the Tsushima Island.

• 중환자간호학회지
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• 제9권2호
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• pp.36-47
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• 2016

Purpose: The study examined core job characteristics and job preference to explain work performance among critical care nurses. The theoretical model was constructed based on the job characteristics model with core job characteristics as exogenous variables, and work performance and job preference as endogenous variables. Methods: A total of 228 hospital nurses participated in the study from May to September, 2015. Data were collected through structured questionnaires and analyzed using structural equation modeling. Results: The model showed a good fit to the data with $x^2/df=2.90$, goodness of fit index = .91, root mean square residual = .20, comparative fit index = .93, and incremental fit index = .93. The core job characteristics explained 64% of the variance in job preference. The core job characteristics and job preference explained 52% of the variance in work performance. Conclusions: The core job characteristics can explain the work performance among critical care nurses through job preference. Effective strategies to improve the work performance among critical care nurses should focus on the application of the core job characteristic into a productive work environment. Further studies are warranted to explore the role of job preference of critical care nurses in promoting their work performance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.266-267
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• 2007

Sandwich sheet with inner structure is expected to find many applications because of high stiffness to mass ratio. In order to simulate forming of sandwich sheet with pyramid core, an effective simulation method is required. Compared to the expensive model using solid elements, cost effective model using simplified elements such as shells and beams is developed. By comparing two models in terms of the cost and accuracy for unit cell deformation, a developed model shows some advantages over the model using solid elements. Evolution of two kind of forming limits, face buckling and core buckling are successfully expressed by developed model. Developed model is also applied in the simulation of square cup drawing and L-type bending. The corresponding experiments are carried out. Deformation shape and wrinkling behavior are compared and discussed. It is found that simulation results using a developed model are in good agreement with experiments.