• 한국전기전자재료학회논문지
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• 제20권2호
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• pp.183-187
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• 2007

Fractal mathematics is being highlighted as a research method for classification of image. But the application of Fractal dimension(FD) has been requited the complicated calculation method because of its complex repetition progressing. In this paper, it has been developed the new approach method to express the Fractal Dimension(FD) for aging level calculation and estimation system of outside insulator using special image processing algorithm. As a result after FD testing, the recognized aging estimation of FD has a very characteristics compared to the conventional visual inspection.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.54-57
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• 2007

Recently, multidimensional joint inversion of geophysical data based on fundamentally different physical properties has been actively studied. Joint inversion can provide a way to much more accurately image the subsurface structure. Through the joint inversion, furthermore, it is possible to directly estimate non-geophysical material properties from geophysical measurements. In this study, I derive the objective functions and normal equations of three different joint inversion approaches: one approach based on the structural similarity using cross-gradient, and the other two using the a priori information on the model parameters and the correlation between material properties. Since all the equations derived in this study are based on the same inversion method (smoothness constrained least-squares), it is possible to mix the joint inversion methods so as to produce a new joint inversion algorithm.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.58-63
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• 2007

We developed a new algorithm for jointly inverting dc resistivity and seismic travel time tomography data based on the multiple constraints: (1) structural similarity based on cross-gradient, (2) correlation between two different material properties, and (3) a priori information on the material property distribution. Through the numerical experiments of surface dc resistivity and seismic refraction surveys, the performance of the proposed algorithm was demonstrated and the effects of different regularizations were analyzed.

• 동굴
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• 제78호
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• pp.9-15
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• 2007

The materials showing high structure dispersion with functional properties were developed on the quartz base and those were obtained by mechano-chemical reaction technology. Depending on the processing conditions and subsequent applications the materials produced by mechano-chemical reaction show concurrently magnetic, dielectric and electrical properties. The obtained magnetic-electrical powders classified by aggregate complex of their features as segnetomagnetics, containing a dielectric material as a carrying nucleus, particularly the quartz on that surface one or more layers of different compounds were synthesized having thickness up to 1050nm showing magnetic, electrical properties and others. The similarity of the structure of surface layers of quartz particles subjected to mechano-chemical processing and nano-structure cluspol (clusters in a polymer matrics) material was alsoconfirmed by the fact that the characteristics of ferromagnetic quartz of insulating nano-composite powder were changed with time, after its preparing process was completed.

• Plant Resources
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• 제8권3호
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• pp.181-187
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• 2005

A cinnamoyl CoA reductase (CCR) cDNA (ClCCR) was isolated from tabroot mRNAs of Codonopsis lanceolata by cDNA library construction, and its expression was investigated in relation to abiotic stresses. The ClCCR is 1008 bp in length with an open reading frame (ORF) of 336 amino acids. The deduced amino acid sequence was showed high similarity with cinnamoyl-CoA reductases of P. tremuloides (AAF43141) 87%, F.${\times}$aranassa (AAP46143) 83%, L. album (CAD29427) 80%, E. gunnii (CAA66063) 72%, S. tuberosum (AAN71761) 83%. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was revealed that the ClCCR expression was regulated by abiotic stresses.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.973-976
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• 2008

In addition to its similarity to genuine diamond film, diamond-like carbon (DLC) film has many advantages, including its wide band gap and variable refractive index. In this study, DLC films were prepared by the RF PECVD (Plasma Enhanced Chemical Vapor Deposition) method on silicon substrates using methane ($CH_4$) and hydrogen ($H_2$) gas. We examined the effects of the RF power on the electrical properties of the DLC films. The films were deposited at several RF powers ranging from 50 to 175 W in steps of 25 W. The leakage current of DLC films increased at higher deposition RF power. And the resistivities of DLC films grown at 50 W and 175 W were $5\times10^{11}$ ${\Omega}cm$ and $2.68\times10^{10}$ ${\Omega}cm$, respectively.

• 유변학
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• 제11권2호
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• pp.122-127
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• 1999

일정한 표면 온도를 갖는 쐐기형 물체 주위를 지나는 미세 극성유체의 정상상태 층류유동에 대하여 고찰하였다. Falkner & Skan에 의하여 유도된 상사해법을 이용하여 유동방향의 비선형 경계층 방정식의 해를 구하였다. 4계 Runge-Kutta법을 사용하여 Pr 수가 1일 경우의 열전달 특성을 수치적으로 해석하였고, 물질 매개변수에 대한 영향을 고찰하였다. 경계층을 가로지르는 무차원 속도와 Nusselt 수의 분포는 쐐기형 물체 주위를 지나는 Newtonian 유체의 경우와 비교하였다. Pr 수가 1이고 일정한 쐐기각을 가질 경우 물질 매개변수 K값이 증가할수록 Newtonian 유체의 경우보다 미세 극성유체의 경우 경계층의 두께가 증가하는 결과를 보였다. 그러나 물질매개변수 K값이 일정할 경우, Newtonian 유체보다 미세 극성유체의 열전달율이 더 작은 경향을 나타내었다.

• 대한기계학회논문집
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• 제17권5호
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• pp.1161-1171
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• 1993

본 연구에서는 모델실험을 통해 실제재료에 관한 정량적인 정보를 얻기 위하 여 모델재료인 플리스티신에 라놀린(lanolin), 레진(resin)등을 첨가하여 새로운 유 동특성을 갖는 혼합 플라스티신을 개발하고자 하였다. 개발된 모델재료와 기존의 플라스티신을 MTS(Material Testing System)을 이용하여 링 압축실험과 실린더 압축 실험으로 온도와 변형률속도 변화에 따라 재료에 혼합된 첨가제가 모델재료의 마찰 특성과 기계적 성질에 미치는 영향을 조사하고 비교 검토하고자 한다. 또한 실제 재료의 다양한 가공공정을 시뮬레이션하기 위한 모델재료의 상사실험에서 다이와 소재 의 분리가 비교적 용이한 윤활제로 실링 페이퍼(sealing paper), 바셀린(vaseline)을 바른 실링페이퍼, 파우다(talc powder)의 마찰특성에 대해서도 연구되었다.그리고 조사된 모델재료들이 연강인 0.15%C강의 고온 (900.deg. C∼1100.deg. C)에서의 온도변화에 따 른 상사재료로 사용될 수 있는지의 타당성을 검토하고자 한다.

• 대한기계학회논문집
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• 제16권11호
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• pp.2082-2089
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• 1992

본 연구에서는 모델링재료를 이용한 AISI4130축대칭 도움형상의 열간 단조 공 정 설계 방안을 이룩하기 위한 실험을 수행하였다. 본 실험에 사용된 모델링 재료는 Van Akan International사 제품의 Plastalina를 이용하였다. 모델링재료와 실제 재 료 사이의 상사성을 검토하기 위해 압축실험을 수행하였는데 압축 실험시 모델링재료 와 평다이 사이의 마찰력을 줄이기 위해 베이비파우더, 휴지, 바셀린, 테프론테잎 등 을 이용하였으며 램 속도, 온도, 그리고 변형률도에 따른 응력 변화를 검토해 보았다. 열간 공정시에 수반되는 금형과 공작물 사이의 마찰력을 알아보기 위해 앞에 열거한 윤활제를 이용한 링실험을 수행하여 전단마찰계수(m) 값의 변화를 알아보고 폐쇄단조 시 주요한 설계방안을 검토하기 위해 플래쉬를 갖는 폐쇄단조 실험을 수행하였다. 이 실험에서는 폐쇄단조시 중요한 설계변수 중의 하나인 플래쉬 두께 대 폭비, 플래쉬 부를 통한 체적손실, 그리고 원기둥모양의 초기 단조 시편 형상비 등에 따른 설계방안 을 검토하여 기존 참고문헌에 나와 있는 결과들과 유사성을 검토하였다. 이와같은 실험 결과를 체계적으로 확립하고 고강도강 대형 단조품생산에 필요한 단조하중 예측, 예비성형체 설계, 성형성 연구등에 대한 응용성을 검토하고자 한다.

• 대한방사선기술학회지:방사선기술과학
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• 제43권6호
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• pp.453-460
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• 2020

The price of the Brain phantom (Hoffman 3D brain phantom) used in nuclear medicine is quite expensive, it is difficult to be purchased by a medical institution or an educational institution. Therefore, the purpose of present research is to produce a low-price 3D brain phantom and evaluate its usefulness by using a 3D printer capable of producing 3D structures. The New 3D brain phantom consisted of 36 slices 0.7 mm thick and 58 slices 1.5 mm thick. A 0.7 mm thick slice was placed between 1. 5 mm thick slices to produce a composite slice. ROI was set at the gray matter and white matter scanned with CT to measure and compare the HU, in order to verify the similarity between PLA which was used as the material for the New 3D brain phantom and acrylic which was used as the material for Hoffman 3D brain phantom. As a result of measuring the volume of each Phantom, the error rate was 3.2% and there was no difference in the signal intensity in five areas. However, there was a significant difference in the average values of HU which was measured at the gray and white matter to verify the similarity between PLA and acrylic. By reproducing the previous Hoffman 3D brain phantom with a 100 times less cost, I hope this research could contribute to be used as the fundamental data in the areas of 3D printer, nuclear medicine and molecular imaging and to increasing the distribution rate of 3D brain phantom.