• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1997년도 추계 학술대회논문집
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• pp.10-15
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• 1997

Unsteady natural convection of an enclosed fluid has been one of the fundamental thermo-fluid problems, of which dynamic relevance is found in many engineering applications. Together with the inherent coupling between the boundary layers and the interior core, and strong interaction between flow and temperature fields, the unsteadiness poses serious hurdles for analytical and experimental approaches. With the recent development of computers and solution algorithms, computational fluid dynamics has become the prevailing tool to tackle the underlying problems. In this presentation, a few examples of numerical studies are introduced. The usefulness and potential of numerical simulations in investigating unsteady natural convection are elaborated.

• Nuclear Engineering and Technology
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• 제30권3호
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• pp.194-201
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• 1998

DYLAM (Dynamic Logical Analytical Methodology) and its related methodologies are reviewed and found to have many favorable characteristics. Previous studies have shown that the DYLAM methodology represents an appropriate tool to study dynamic analysis. A hybrid model which is a synthesis of the DYLAM model, a system thermodynamic simulation model and a neural network predicative model, is implemented and used to analyze dynamically the CANDU pressurizer system. This study demonstrates that the hybrid model for system reliability analyses is effective.

• Journal of Information Science Theory and Practice
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• 제5권1호
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• pp.6-14
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• 2017

Information culture is a concept with multiple and sometimes conflicting definitions. Nevertheless at a time when social and cognitive aspects of information and communication systems are recognized as being of similar significance as the technological functionality, the concept of information culture is demonstrating considerable value. This paper explains the concept of information culture and considers its value from two main perspectives: firstly as providing an analytical tool, and secondly as a means of providing practitioners with insight and sensitivity to the organisational contexts of their workplaces.

• Korean Journal of Mathematics
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• 제27권2호
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• pp.487-503
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• 2019

In this study, the author provided a discussion on one dimensional Laplace and Fourier transforms with their applications. It is shown that the combined use of exponential operators and integral transforms provides a powerful tool to solve space fractional partial differential equation with non - constant coefficients. The object of the present article is to extend the application of the joint Fourier - Laplace transform to derive an analytical solution for a variety of time fractional non - homogeneous KdV. Numerous exercises and examples presented throughout the paper.

• 한국정밀공학회지
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• 제13권12호
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• pp.120-128
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• 1996

An attempt is made to characterize and synthesize engineered surfaces. The proposed method is not only an analytical tool to characterize but also to generate/synthesize three-dimensional surfaces. The developed method expresses important engineered surface characteristics such as the autocorrelation or power spectrum density functions in terms of the two-dimensional autoregressive coefficients.

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1185-1191
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• 2011

The kinematic characteristics of cutting device significantly affects cutting performance in 2-dimensional elliptical vibration cutting(EVC) where the cutting tool cuts workpiece, traversing a micro-scale elliptical trajectory in a trochoidal motion. In this study, kinematical characteristics of EVC device constructed with two parallel stacked piezoelectric actuators were analytically modeled and compared with the experimental results. The EVC device was subjected to step and low-frequency(0.1 Hz) sinusoidal inputs to reveal only its kinematical displacement characteristics. Hysteresis in the motion of the device was observed in the thrust direction and distinctive skew of the major axis of the elliptical trajectory of the cutting tool was also noticed. Discrepancy in the voltage-to-displacement characteristics of the piezoelectric actuators was found to largely contribute to the skew of the major axis of the elliptical trajectory of the cutting tool. Analytical kinematical model predicted the cutting direction displacement within 10 % error in magnitude with no phase error, but in estimating the thrust direction displacement, it showed a $27^{\circ}$ of phase-lag compared with the measured displacement with no magnitude error.

• 한국정밀공학회지
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• 제30권12호
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• pp.1313-1320
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• 2013

An ultraprecision multi-axis machine tool has been designed and developed in our laboratory. The machine tool has four moving axes which are composed of three linear axes and one rotational axis. It has a gantry type structure and the Z-axis is on the X-axis and the C-axis, on which a workpiece is located, is inside the Y-axis. This paper shows control performance improving method and procedure for the ultra-precision positioning control of a hydrostatic bearing guided linear axis. Through improvements of electrical and mechanical components for the control system such as control electronics and oil pumping systems, the control disturbing noise is decreased. Also by the frequency domain analysis of control system those problem-making system components are identified and modified with analytical methods. The controller is analyzed and designed from frequency domain data and system information. In the experimental control results the nanometer order control result is successfully presented.

• 분석과학
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• 제14권2호
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• pp.95-102
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• 2001

쇠고기 돼지고기 속에 포함된 nonylphenol, octylphenol, bis(2-ethyltexyl) phthalate의 동시 정량방법을 연구하였다. 이 방법에서는 밀폐된 배양시험관에서 이염화메탄을 이용하여 추출하고 용매를 이소헥산으로 바꾸고 aminopropyl 칼럼(2g)을 이용하여 분리한 후 GC/MS-SIM 방법으로 분석하였다. 다중점보정을 위한 nonylphenol(NP), octylphenol(OP), bis(2-ethylhexyl) phthalate(BEHP)의 회수율에서 NP, OP는 $0.125-12.5{\mu}g/g$, BEHP는 $0.0125-12.5{\mu}g/g$ 범위에서 좋은 회수율을 보였다. 확립된 방법을 전주시와 전주시 근교 마트와 정육점에서 구입한 16점의 쇠고기 돼지고기 시료에 적용하였다. Nonylphenol은 4점의 시료에서 검출되었으며 bis(2-ethlhexyl) phthalate는 전 시료에서 검출되었고, 그 농도범위는 $0.06-0.24{\mu}g/g$과 $0.36-2.35{\mu}g/g$ 이었다. Octylphenol은 어떠한 시료에서도 검출되지 않았다. 이 방법은 매우 적은량의 생체 시료에도 쉽게 적용이 가능하였다.

• 산업경영시스템학회지
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• 제38권3호
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• pp.87-94
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• 2015

Recently, management based on statistical data has become a big issue and the importance of the statistics has been emphasized for the management innovation in the defense area. However, the Military Management based on the statistics is hard to expect because of the shortage of the statistics in the military. There are many military information systems having great many data created in real time. Since the infrastructure for gathering data form the many systems and making statistics by using gathered data is not equipped, the usage of the statistics is poor in the military. The Analytical Defense Statistics System is designed to improve effectively the defense management in this study. The new system having the sub-systems of Data Management, Analysis and Service can gather the operational data from interlocked other Defense Operational Systems and produce Defense Statistics by using the gathered data beside providing statistics services. Additionally, the special function for the user oriented statistics production is added to make new statistics by handling many statistics and data. The Data Warehouse is considered to manage the data and Online Analytical Processing tool is used to enhance the efficiency of the data handling. The main functions of the R, which is a well-known analysis program, are considered for the statistical analysis. The Quality Management Technique is applied to find the fault from the data of the regular and irregular type. The new Statistics System will be the essence of the new technology like as Data Warehouse, Business Intelligence, Data Standardization and Statistics Analysis and will be helpful to improve the efficiency of the Military Management.

• 대한환경공학회지
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• 제32권5호
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• pp.455-460
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• 2010

본 연구에서는 프탈레이트 화합물 측정 시 시료채취 및 분석과정 증에서 야기될 수 있는 공시료의 오염여부를 평가하고 clean-up 절차와 같은 적절한 개선 방안을 제시하였다. 실험도구 및 시료채취 매체에 대한 공시료를 평가한 결과 많은 종류의 실험기구 및 장치에서 DBP와 DEHP가 잔존하는 것으로 나타났다. 따라서 실험도구는 반드시 전처리하여 사용해야 하며, 이후 공시료 보정이 수반되어야 한다. 또한 본 연구에서 제시한 clean-up 방법을 통해 불순물이 많이 제거되었으며, GC/MS를 이용한 정성?정량분석에서 정도개선에 효과적인 것으로 나타났다.