• Carbon letters
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• 제6권2호
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• pp.101-105
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• 2005

Like bamboo-sprouts after rains, numerous sub${\mu}m$-sized pyrocarbon whiskers growth on the Mullite ($3Al_2O_3{\cdot}2H_2O$) substrate could be observed through a looking glass during methane pyrolysis at the temperature of $1050^{\circ}C$ in this study. If the surface of substrate would be scrubbed strongly with iron metals, then finely sticked iron particles were more effective catalytic for nm-sized whisker growth. Numerous fine flakes of pyrolytic carbon were hanging by invisible nm-whiskers as like as small spiders hanging by a spiderweb. This is the identification of nm-sized whisker growth. Therefore if the pyrolysis would be stopped at the initial stage of the whisker growth, the primary lengthening growth was nm-sized whisker. So could we vary arbitrarily sizes of whisker from nm- to ${\mu}m$-sizes. But ${\mu}m$- and nm-whiskers grown with the different growth mechanism; the former was straight and the latter has twigs, The lengthening growth of whisker was depended on the flow pattern pyrolysis species on the active sites of substrate and on the growth duration. We could obtained straight whisker length of 10~20 ${\mu}m$/min during the primary growth and laboratory spiral whisker of 30~40 ${\mu}m$-diameter/hr during the secondary growth.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.174-175
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• 2005

Initial growth stage was investigated for SiC homoepitaxial film growth using 'step controlled epitaxy' technique. When the off angel direction is located parallel along to the gas flow direction, the smoother surface can be obtained. On the on axis substrates, selective etching was detected both the etching and growth condition. It was deduced that the high ratio of C/Si in the source gas results in well developed steps and etched spiral around micropipes.

• 미생물과산업
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• 제18권3호
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• pp.23-33
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• 1992

The general characteristics of campylobacters and related organisms (e.g., species of the genera Helicobacter and Wolinella, Bacteroides ureolyticus, and Bacteroides gracilis) are as follows: slender, non-sporeforming, gram-negative, vibroid bacteria (helical- or spiral- shpaed; except that B. ureolyticus and B. gracilis are straight-rod), 0.2-0.5 .mu.m in width and 0.5 .mu.m in length. (Smibert, 1984; Penner, 1988). The species of genus Campylobacter and related organisms are chemoorganotrophs; however, they neither oxidize nor ferment carbohydrates and instead obtain energy from amino acids, the salts of tricarboxylic acids (TCA) cycle intermediates, the salts of organic acids, or, in some species, H$\_$2/. With regard to their oxygen responses for growth, they all are microaeophilic i.e., they are capable of oxygen-dependent growth (respiring with oxygen as a terminal electron acceptor) but can not grow in the presence of a level of oxygen equivalent to that present in an air atmosphere (21% oxygen). This review will take interests in how these microorganisms response to oxygen for growth and what repiratory types they have.

• 한국융합학회논문지
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• 제8권8호
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• pp.185-190
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• 2017

자연현상에서 발견되는 프랙털 (fractal) 구조는 자기 유사성 (self-similarity)의 반복된 형태로, 생명체의 발생과 기관 형성에서도 자주 관찰된다. 특히, 수많은 종류의 암모나이트에서 관찰되는 봉합선 (suture)의 복잡, 다양한 형태는 프랙털 생성에 대한 생물학적인 이해를 위한 좋은 연구소재이다. 본 연구에서는 희귀하게 초기 발생단계의 봉합선 구조가 매우 잘 보전된 Eogaudryceras sp.를 대상으로 봉합선 형성의 과정을 분석하고자 하였으며, 일반적으로 구하기 힘든 부위인 나선 (spiral) 중심부 1mm 이내의 현미경적인 관찰을 실시하였다. 아직 봉합선의 프랙털 구조 생성에 대한 생물학적인 기전은 아직 불분명한 상태이나, 본 연구를 통하여 암모나이트 발생초기에 프랙털 구조의 복잡성이 단계별로 분명한 차이가 있음을 발견하였다. 이러한 결과는 하나의 생명체 내에서 "Evo-Devo"의 여러 발생단계의 변화를 동시에 보여줄 수 있는 좋은 예시로서, 향후 프랙털 구조의 생물학적인 기전 연구 및 관련되는 다양한 융합학문에서의 접목과 활용이 기대된다.

• Journal of the Korean Wood Science and Technology
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• 제9권1호
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• pp.1-12
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• 1981

The structure of spiral thickenings, particulary the appearance, arrangement and orientation of thickenings in compression wood of Torreya nucifera, were studied in detail by light and polarizing microscope, scanning and transmission electron microscope. The results obtained are as follows: (1) Using the inclined sections at an angle of 45 degrees to the fiber axis, it seems that we can not only observe the more accurate transverse view of the thickenings but also investigate the formation of their thickenings. (2) Generally 2-4 pieces of thickenings are projected to the cell lumen as nipple-like appearance in transverse section and are as frequent, well developed, forming pair and have the rope-like appearance in radial surface. (3) The secondary wall of early wood is composed of 3 layers (S1, S2, S3) and orientation of thickening appears S helix but that of late wood is of 2 layers (S1, S2) and that orientation shows Z helix. Above two regions are demaracted at several tracheid cells from the growth ring boundary. (4) Orientation of thickening seems to be a element showing the characteristics of compression wood in Torreya nucifera. (5) It believes that the thickenings of compression wood are integral part of the S3 in early wood tracheids and of the S2 in late wood and have the same orientations as the inner-most microfibrils in these layers. (6) Thickening and cavities seem to be not formed together in a secondary cell wall of same tracheids.

• 미생물학회지
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• 제25권3호
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• pp.238-243
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• 1987

본 실험에서는 숲속 토양으로부터 산성조건에서 생장이가능한 내산성 균주를 분리 동정하였다. 분리된 균주는 형태적 관찰과 박층 크로마토그래피에 의한 세포벽 분석과 ISP 분류 기준에 따른 생리적 실험을 통하여 동정하였으며, 이 균주의 포자는 형태가 간상형이고 표면구조는 매끈한 형태였다. 포자의 배열형태는 compact spiral 구조였으며 이 균주는 명확한 포자낭벽을 갖고 있지 않았고, 세포벽 분석결과에 따르면 Streptomyces 속에 속하는 것으로 밝혀졌다. 또한 중성조건에서 생장이 우수하나 산성조건에서도 생장이 가능한 내산성 균주로써, Nonomura의 분류 기준에 의하면 Streptomyces mirabilis인 것으로 동정되었다.

• 미생물학회지
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• 제27권3호
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• pp.285-290
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• 1989

한국에서 분리한 비유황 광합성 세균 Rhodospirillum rubrm KS-301 생장에 대하여 논 잡초제로 널리 쓰이는 butachlor(제품명 Machete)의 영향을 본 것이다. 실제 논에서 사용되고 있는 농노인 $10^{-3}$에서도 균의 생장은 이루어졌고 $10^{-2}$M의 농도에서 억제되어 다른 생물체보다 높은 저항력을 가지는 것으로 나타났다. 더욱이 pyruvate를 탄소원으로 하여 질소고정 상태로 배양했을 때 butachlor를 처리한 실험군에서 미약하나마 오히려 생장이 촉진되었다. (1%). 전자현미경으로 내부막조직을 관찰한 결과 Rhodospirillum rubrum의 전형적인 vesicular type이 tubular type으로 변형된 것으로 보아 제초제의 흡수가 간접 확인되었다. 또한 pH가 알칼리 조건일 때 질소고정상태에서 균생장에 대한 제초제의 저해력이 떨어지는 것으로 나타났다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권1호
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• pp.429-433
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• 2013

Objectives: To explore the correlation between multi-slice spiral CT (MSCT) perfusion parameters and the expression of vascular endothelial growth factor (VEGF) as well as matrix metalloproteinase-2 (MMP-2) in breast cancer. Methods: Forty five breast cancer patients and 16 patients with benign breast tumor, both confirmed by pathology examination, were enrolled. All underwent MSCT perfusion imaging to obtain perfusion maps and data for parameters including blood flow (BF), blood volume (BV) and permeability surface (PS). Cancer patients did not receive treatment prior to surgery. The expression of VEGF and MMP-2 were examined with both immunohistochemistry and Western blotting. Results: The levels of VEGF and MMP-2 by immunohistochemistry were significantly higher in the breast cancer group (P < 0.01) than the benign tumor group. Relative OD values from Western blotting were also higher in cancer cases (P < 0.05). Similarly, the mean MSCT perfusion parameters (BF, BV, PS) were significantly higher in the breast cancer group (P < 0.01), BF and BV positively correlating with VEGF expression (r = 0.878 and 0.809 respectively, P < 0.01); PS and VEGF and MMP-2 expression were also positively correlated (r= 0.860, 0.786 respectively, P < 0.01). Conclusion: There is a correlation between breast cancer MSCT perfusion parameters and VEGF andMMP-2 expression, which might be useful for detection of breast lesions, qualitative diagnosis of breast cancer, and evaluation of breast cancer treatment.

• 한국결정성장학회지
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• 제8권1호
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• pp.1-9
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• 1998

본 연구에서는 냉각매체로서 물을 이용하는 수정된 열교환법을 이용하여 45$\times$45$\times$20(mm) 크기의 사각단면 형상의 sapphire 단결정의 제조가능 조건에 대하여 조사하였다. 온도에 따른 성장로 내의 압력 변화로부터 사파이어의 용융 및 응고 과정을 추적할 수 있었으며, 이로부터 sapphire 단결정은 1970~$1960^{\circ}C$에서 응고가 완료됨을 알 수 있었다. 도가니 성형시 이루어지는 '귀'의 형태는 도가니 벽면과 접촉되지 않는 '나선형태'이어야 한다. 열유출부는 융액 내의 온도구배를 지배하며 융액내의 열유속과 씨앗 결정의 흔적은 Mo 봉의 체적 변화로서 조절할 수 있었다. 기공 형성을 억제하기 위해서는 $0.2^{\circ}C$/min 이하의 발열체의 냉각속도가 요구되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.622-622
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• 2013

Piezoelectric energy harvesting (PEH) device refers to a power device for acquiring mechanical energy from the environment surrounding us which would otherwise be wasted and for converting it into usable electrical energy. While much work has been done on developing ZnO nanogenerator (NG) with nanowire arrays, there are some issues of not only scaling up its output power but also optimizing structure for operating feasibly in various conditions. Efficiency of NG is highly dependent on fixed orientation. But in many cases, it is not easy to predict where the pressure and vibration may come from. Furthermore, the direction of the applied mechanical stress is usually non-stationary and can be random in various practical applications. Therefore an omnidirectional PEH is needed.In this work, we investigate an omnidirectional PEH device consisting ZnO nanowires. We deposited spiral patterned ZnO seed layer on Kapton film. We deposited thin Cr layer on the ZnO seed layer using DC-sputter to form a passivation layer to retard un-expected growth of ZnO nanowires. We grew ZnO nanowires along the spiral arms using hydrothermal method. ZnO nanowires have been selectively grown from the ZnO sidewall without Cr layer and have the average length of$5{\mu}m$ and the average diameter of 40nm. We reduced the defect in the as-grown ZnO nanowires by O2 plasma using asher and by thermal treatment using RTA. Consequently, each nanowire has different directions to each other. This isotropic design can lead to the omnidirectional power generation. The morphology of NG is characterized with FESEM. Maximum output power of the device is measured by using a picoammeter and a nanovoltmeter.