• 응용통계연구
• /
• 제19권2호
• /
• pp.283-290
• /
• 2006

일반적으로 Box-Cox변환과 같은 류의 멱변환은 분산 안정화 혹은 분포의 대칭성 향상 등을 목적으로 사용된다. 그러나 원 자료의 평균의 크기가 크면서 분산이 상대 적으로 작은 경우, 즉 변동계수가 작은 경우에는 제대로 작동하지 않는 것이 알려져 있다. 본 논문에서는 이러한 문제점을 해결하기 위한 이동-멱변환을 제안하고 모의실험과 실제 자료 분석을 통하여 그 효과를 확인하였다.

• 대한수학회지
• /
• 제41권6호
• /
• pp.957-976
• /
• 2004

It is well known that the application of the nonlinear coordinate transformations is useful for efficient numerical evaluation of weakly singular integrals. In this paper, we consider the trapezoidal rule combined with a nonlinear transformation $\Omega$$_{m}$(b;$\chi$), containing a parameter b, proposed first by Yun [14]. It is shown that the trapezoidal rule with the transformation $\Omega$$_{m}$(b;$\chi$), like the case of the Gauss-Legendre quadrature rule, can improve the asymptotic truncation error by using a moderately large b. By several examples, we compare the numerical results of the present method with those of some existing methods. This shows the superiority of the transformation $\Omega$$_{m}$(b;$\chi$).TEX>).

• 한국자동차공학회논문집
• /
• 제8권1호
• /
• pp.10-16
• /
• 2000

Spatially resolved liquid volume fractions from a set of line-of-sight laser diffraction measurements for axisymmetric sprays generated from a pintle-type gasoline injector have been tomographically reconstructed by Abel transformation, Fourier transformation and onion peeling method. Spatially resolved liquid volume fractions classified into 32 size groups were translated characteristics of SI engine fuel sprays. These data were also obtained from the phase Doppler measurements for the same sprays. The comparison between laser deffraction measurements and transformation reconstructs more reasonable spatially resolved characteristics for axisymmetric sprays as well as for asymmetric sprays.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 하계학술대회 논문집 C
• /
• pp.1507-1509
• /
• 1997

Property of insulation of electric machine is severely affected by process of electrical tree growing. Partial discharges(PD) have been used to determine degradation of insulations. In this paper, PD quantities detected and analyzed are PD magnitudes, repetition rates, phase angle distribution of PD pulses, and wavelet transformation. The wavelet transformation is an extended method of fourier transformation. The fourier transformation is a powerful tool for signal analysis, but it can't include informations for time. However the wavelet transformation analysis can include on the informations of time and frequencies at the same time. This paper discusses correlation between process of electrical tree growing and characteristics of PD in LDPE specimens.

• Mycobiology
• /
• 제29권3호
• /
• pp.132-134
• /
• 2001

Since it is known that Agrobacterium tumefaciens, which has long been used to transform plants, can transfer the T-DNA to yeast Saccharomyces cerevisiae during tumourigenesis, a variety of fungi were subjected to transformation to improve their transformation frequency. In this study, I report the A. tumefaciens-mediated transformation of filamentous fungus Aspergillus niger. Transfer of the binary vector pBIN9-Hg, containing the bacterial hygromycin B phosphotransferase gene under the control of the Aspergillus nidulans trpC promoter and terminator as a selectable marker, led to the selection of $50{\sim}100$ hygromycin B-resistant transformants per $1{\times}10^7$ conidia of A. niger. This efficiency is improved $10{\sim}20$ fold more than reported elsewhere. In order to avoid the difficulties in selection transformant from the over-growing non-transformant, I used top agar containing 900 ${\mu}g/ml$ of hygromycin. Genomic PCR and Southern analysis showed that all transformants contained single T-DNA insert per fungal genome. This technique offers an easier and more efficient method than that of using protoplast.

• 대한조선학회지
• /
• 제18권4호
• /
• pp.13-20
• /
• 1981

The hydrodynamic added mass of two dimensional cylinders oscillating vertically at high frequencies in the free surface is of interest to ship vibration problems. Conformal transformation is one of the methods commonly in use for computing the inertia coefficient. Especially, Schwarz-Christoffel transformation has been employed to evaluate the inertia coefficient for the cylinders of straight frames and chines. In this paper, the inertia coefficient for the cylinders with round corners in vertical oscillation at high frequencies are evaluated by employing the Schwarz-Christoffel transformation for the concave corner. The results of calculation by employing the Schwarz-Christoffel transformation are found to be well within the expected range of values compared to Lewis form and the results obtained by source distribution method.

• 한국분말재료학회지
• /
• 제8권1호
• /
• pp.42-49
• /
• 2001

Ti-50Ni(at%) and Ti-40Ni-10Cu(at%) alloy powders have been fabricated by ball milling method, and their microstructure and phase transformation behavior were investigated by means of scanning electron microscopy/energy dispersive spectrometry, differential scanning calorimetry (DSC), X-ray diffractions and transmission electron microscopy. In order to investigate the effect of ball milling conditions on transformation behavior, ball milling speed and time were varied. Ti-50Ni alloy powders fabricated with the milling speed more than 250 rpm were amorphous, while those done with the milling speed of 100rpm were crystalline. In contrast to Ti-50Ni alloy powders, Ti-40Ni-10Cu alloy powders were crystalline, irrespective of ball milling conditions. DSC peaks corresponding to martensitic transformation were almost discernable in alloy powders fabricated with the milling speed more than 250 rpm, while those were seen clearly in alloy powders fabricated with the milling speed of 100 rpm. This was attributed to the fact that a strain energy introduced during ball milling suppressed martensitic transformation.

• Journal of information and communication convergence engineering
• /
• 제20권4호
• /
• pp.265-272
• /
• 2022

The most effective method to improve information system capabilities is to enable instant access to several relational database sources and transform data with a logical structure into multiple target relational databases. There are numerous data transformation tools available; however, they typically contain fixed procedures that cannot be changed by the user, making it impossible to fulfill the near-real-time data transformation requirements. Furthermore, some tools cannot build object references or alter attribute constraints. There are various situations in which tool changes in data type cause conflicts and difficulties with data quality while transforming between the two systems. The R-programming language was extensively used throughout this study, and several different relational database structures were utilized to complete the proposed study. Experiments showed that the developed study can improve the performance of information systems by interacting with and exchanging data with various relational databases. The study addresses data quality issues, particularly the completeness and integrity dimensions of the data transformation processes.

• International Journal of Computer Science & Network Security
• /
• 제23권4호
• /
• pp.39-47
• /
• 2023

This study compares various transformation techniques for multifocus image fusion. Multi-focus image fusion is a procedure of merging multiple images captured at unalike focus distances to produce a single composite image with improved sharpness and clarity. In this research, the purpose is to compare different popular frequency domain approaches for multi-focus image fusion, such as Discrete Wavelet Transforms (DWT), Stationary Wavelet Transforms (SWT), DCT-based Laplacian Pyramid (DCT-LP), Discrete Cosine Harmonic Wavelet Transform (DC-HWT), and Dual-Tree Complex Wavelet Transform (DT-CWT). The objective is to increase the understanding of these transformation techniques and how they can be utilized in conjunction with one another. The analysis will evaluate the 10 most crucial parameters and highlight the unique features of each method. The results will help determine which transformation technique is the best for multi-focus image fusion applications. Based on the visual and statistical analysis, it is suggested that the DCT-LP is the most appropriate technique, but the results also provide valuable insights into choosing the right approach.

• 기술혁신연구
• /
• 제30권1호
• /
• pp.1-20
• /
• 2022

디지털 전환(digital transformation)은 디짓화(digitisation)와 디지털화(digitalisation)의 경제적 및 사회적 효과를 의미한다. 디지털 전환은 경제/사회 발전 및 삶의 편의성을 향상시키는 유용한 도구로 작용하지만 부정적 영향(개인정보 오남용, 윤리문제 야기, 사회적 격차 심화 등)을 미칠 수도 있는 양면성을 보유하고 있다. 한편 정부는 산업 경쟁력 및 기술 패권 확보 등을 위하여 디지털 전환 촉진정책은 적극적으로 추진하고 있는 반면, 디지털 전환 관련 위험이슈에 대한 이해와 이를 방지할 수 있는 정책 추진에는 상대적으로 소극적인 상황이다. 이에 본 연구는 디지털 전환이 초래할 수 있는 미래사회 위험이슈를 Embedded Topic Modeling 방법론 기반의 언론기사 빅데이터 정량분석으로 체계화 및 구체화하고, 정책적 대응 방향을 제시하였다. 이를 위하여 먼저 주요국의 디지털 전환 역기능 세부 이슈들을 규명하였다. 다음으로 디지털 전환의 핵심 기술인 인공지능을 중심으로 주요국과 한국의 디지털 전환 역기능 세부이슈를 구체화하고, 비교분석하였다. 아울러 분석결과들을 종합하여 향후 정부의 디지털 전환 역기능 대응 정책 수립 방향을 제시하였다. 분석 결과에 근거한 정책적 함의는 다음과 같다. 첫째, 디지털 전환의 역기능은 기술 분야에만 한정되어 나타나지 않고 국가안보 및 사회 전반에 영향을 미치기 때문에 정부는 디지털 전환의 순기능 촉진뿐만 아니라 역기능 대응을 위한 정책도 마련해야 한다. 둘째, 디지털 전환의 미래사회 위험 세부이슈들은 국가에 따라 상이하게 나타나므로 정부는 국가적/사회적 맥락을 고려하여 디지털 전환 역기능 대응 정책을 수립해야 한다. 마지막으로 정부는 이해관계자들의 혼선을 최소화할 수 있도록 디지털 전환 역기능 대응 정책의 큰 방향을 설정하고, 실효성 있는 정책 수단을 마련해야 한다.