• Transactions of Materials Processing
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• v.17 no.6
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• pp.443-448
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• 2008

Fiber reinforced injection molded parts are widely used in recent years because of their improved properties of materials such as specific stiffness, specific strength, and specific toughness. The demand for products with high precision is increasing and it is important to minimize the warpage of the products. The warpage of short-fiber reinforced product is caused by anisotropy induced by fiber orientation as well as the residual stresses induced during the molding process. In order to reduce the warpage of the part, it is important to achieve successful mold design, processing control, and part design. In the present study, the design of gating system, molding condition, and part structure were carried out and verified with numerical analysis using a commercial CAE code Moldflow. The numbers and locations of gates were iteratively determined, and the molding conditions which can decrease the warpage of the part were investigated. Finally, slight structural modification of the part was conducted to reduce the locally concentrated warpage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.902-909
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• 2003

Screw compressor type chillers are widely used in refrigeration for capacity over 30 RT. In general, chillers operate under part-load conditions. Therefore, information on characteristics at part-load is very important in view of chiller performance and energy economy. In this study, performance tests of part-load and economizer system using R22 and R407C have been performed for various secondary fluid temperatures. Adoption of an economizer system increased the cooling capacity and improved COP except for lower part-load condition when injection volume ratio is 1.01. For the same cooling capacity condition at part-load, COP of both non-economizer and economizer system showed similar values.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.3
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• pp.55-63
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• 1994

Optional two-part tariffs are in growing use in telecommunication services markets. This paper considers the problem of designing profit-maximizing optional two-part tariffs for heterogeneous user groups. It is shown that, at an optimum, one of usage charges among a set of optional two-part tariffs should be made equal to marginal cost. It is also shown that, if demand curves cross, then one of usage charges at the optimum can be below marginal cost. An example with linear demand functions is given to illustrate the important features of optimal two-part tariffs.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.68-74
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• 2000

The STL file format is an approximation of 3-D model with triangular facets. STL is a standard input file format of Rapid Prototyping(RP) equipment In computer graphics a circle has been approximated with an inscribed polygon which causes an error between the real and approximated circles. In this study an intersecting polygon has been used to approximate the circle and applied to produce more accurate RP part. The newly proposed method shows it's excellence in part accuracy.

• Bulletin of the Korean Mathematical Society
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• v.34 no.2
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• pp.199-204
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• 1997

To develope the theory of BCI-algebras, the idel theory plays an important role. The first author [4] introduced the notion of T-ideal in BCI-algebras. In this paper, we first construct a special set, called T-part, in a BCI-algebra X. We show that the T-part of X is a subalgebra of X. We give equivalent conditions that the T-part of X is an ideal. By using T-part, we provide an equivalent condition that every ideal is a T-ideal.

• Proceedings of the KSPS conference
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• 2003.10a
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• pp.25-28
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• 2003

The aim of this paper is to analyze the pathological voice by separating signal into periodic and aperiodic part. Separation was peformed recursively from the residual signal of voice signal. Based on initial estimation of aperiodic part of spectrum, aperiodic part is decided from the extrapolation method. Periodic part is decided by subtracting aperiodic part from the original spectrum. A parameter HNR is derived based on the separation. Parameter value statistics are compared with those of Jitter and Shimmer for normal, benign and malignant cases.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.35-36
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• 2012

Part load operation usually covers large periods of the total operation time on the economic ground and electricity demand in small-scale boilers. Performance analysis of part load behavior is very important for the purpose of boiler operation optimization. A simple thermal calculation approach is applied to predict performance of a pilot-scale circulating fluidized bed (CFB) boiler at part load operation. Verification has been carried out by comparing between calculation results an operation data of the boiler.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.34
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• pp.91-97
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• 1995

This paper presents a possible application of artificial neural network in CM system design. CM systems can be designed based on product lines, part characteristics or part routines. GT(Group Technology) which uses part characteristics to design cells is widely applied, however, the identification of the part-machine families is the fundamental problem in the design process. A heuristic procedure using SOFM which requires only part-machine incidence matrix is proposed in this research. Comparison studies on ZODIAC and ROC with SOFM model are done and the results are discussed and summarized in this paper.

• Electronics and Telecommunications Trends
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• v.9 no.1
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• pp.25-36
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• 1994

통신 시스템의 확실한 연속 서비스 목표를 만족시키기 위한 최적의 spare part 수준을 결정하는 데에는 고장률과 spare part의 인도기간이 크게 기여한다. 따라서 본고는 관련 비용인자와 함께 통신시스템의 최적 spare part 수준결정모델의 결정에 관해 중점을 두고 서술하였다. 이 모델은 통신시스템을 구성하는 plug-in PBA의 spare 수준을 결정하는데 유용하게 적용될 것이며 또한 연도별 시설 공급계획에 의거 운용보전국(OMC) 단위로 적용할 때 특히 유용할 것이다.

• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.1167-1179
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• 2022

In this paper, we obtain some subsets of real numbers (ℝ) on which a fractional part function is defined as a real-valued continuous function. This gives rise to the analysis of the continuous properties of the fractional part function as a real-valued function. The analysis of fractional part function is helpful in the study of the dynamics of circle.