• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.113-113
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• 2011

알루미늄 박막 커패시터 제작을 위해 선택적인 알루미늄 etching과 anodizing을 이용한 유전체($Al_2O_3$) 형성, 전극층 형성을 위한 무전해 Ni-P 도금을 진행하였다. $5{\mu}m$ patterns/$10{\mu}m$ space를 가지는 dot patterns을 알루미늄 기판에 patterning하고, 이를 각각의 전류밀도 조건에서 etching한 후, barrier type anodizing을 진행하였다. 유전체에 전극층은 무전해 Ni-P 도금을 통해 형성하였으며, 이렇게 제작된 알루미늄 박막 커패시터 특성을 평가하였다.

• Applied Microscopy
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• 제28권4호
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• pp.447-463
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• 1998

This study was carried out to investigate the histomorphological changes and the electrophoretic patterns of egg components, obtained from 100 of 2-year-old female catfishes (Silurus asotus). Female Korean catfishes collected in the vicinity of Chollabukdo have synchronous ovaries which discontinously ovulate eggs during the breeding season (from late May until early July). The fishes were killed by severing the spinal cord just posterior to the head after immobilization with tricaine methanesulfonate (MS 222). Especially, the light microscopic and ultrastructural changes of ooplasm and follicular membranes of oocytes, were examined by means of light and transmission electron microscopy. The size of the nucleoli and number of the yolk granules increased as the oocyte groved. Yolk granules were deposited in the oocyte as fluid Due to tile presence of large early and late maturing oocytes, their ovaries were enlarged, transparent, granular and greenish in color. As the percentages of fish in late maturing oocyte (LMO) and ripe oocyte (RO) stage increased from March to April, mean gonadosomatic index (GSI) values (19.95%) increased. Zona radiata changed from squamous into cuboid in shape in the early maturing oocyte (EMO) stage. Processes, microvilli, from the zona radiata and from the oocyte grow, and make contact with each other in the pore canals of the zona radiata during vitellogenesis, but are withdrawn as the zona radials becomes more compact and devoid of pore canals during oocyte maturation. Seasonal changes in the microscopic appearance of the ovaries were well correlated with those in both gonadosomatic index and macroscopic appearance. The main cytological changes such as increase in size of cell, nucleus, nucleolus, and increase in number of nucleoli and mitochondria demonstrated with electron microscopy in the previtellogenic oocytes of Korean catfish, provided evidences for important synthetic processes in an early preparatory phase of oocyte development. The electrophoretic pattern of major band in mature stage was much thicker (24 k, 66 k, 90-110k dalton) than that in previtellogenic phase.

• Tribology and Lubricants
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• 제26권6호
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• pp.311-316
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• 2010

Surface texturing of micro dimple or pore-shaped pattern was prepared using a fiber laser system. Surface texturing was designed to have a square pattern with a particular pitch distance for each corresponding density of 5, 10, 20, and 30%. Thermal damages such as bulges and burrs formed during laser irradiation were observed around the dimples. Thermal damages were later removed by lapping using alumina particles of $0.3{\mu}m$ in diameter. Oscillating friction tests were performed against heat-treated high speed steels under lubricated condition. The lubricant used was SAE 5W-30 automotive engine oil. Normal contact pressure and oscillating frequency was 0.28 MPa and 20 Hz, respectively. The tests were continued for 20 minutes, and friction plots were recorded for examination. Results revealed that the coefficient of friction was lowered regardless of texturing density. Moreover, the lowest coefficient of friction was obtained for 10% density texturing. It is attributed to increased lubricity due to the introduction of surface texturing. In addition, it is concluded that the optimum texturing density and pattern must be found for the best lubricity and low friction.

• 한국안전학회지
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• 제17권1호
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• pp.54-60
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• 2002

To obtain the breakthrough characteristics for the design of fixed bed adsorption plant, adsorption experiment on granular activated carbon was performed with tharonil in the fixed bed. The pore diffusivity and surface diffusivity of tharonil estimated by the concentration-time curve and adsorption isotherm were $D_s=2.825{\times}10^{-9}cm^2/s,\;D_p=1.26{\times}10^{-5}cm^2/s$, respectively. From comparison of the pore diffusivity and surface diffusivity, it was found that surface diffusion was controlling step for intrapaticle diffusion. The breakthrough curve predicted by constant pattern-linear driving force model were shown to agree with the experimental results. The surface diffusivity and film mass transfer coefficient had no effect on the theoretical breakthrough curve but the adsorption isotherm had fairly influence on it. Appearance time of breakthrough curve is faster with the increase flow rate and inflow concentration of liquid. The utility of granular activated carbon is enhanced with the increase of bed height and with the decrease of inflow rate.

• 화약ㆍ발파
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• 제23권2호
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• pp.23-35
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• 2005

지하수로 포화된 암반내의 공동을 굴착하면 공동 주위에서 응력의 재분배로 인하여 초기 공극수압의 변화가 발생한다. 이러한 공극수압의 변화는 다시 암반의 역학적 거동에 영향을 미치게 된다. 그러므로 공동 주변 암반에서 굴착으로 인해 형성된 공극수압이 소산과정에서 암반의 거동은 공극수압의 변화를 고려하지 않은 해석과 차이를 보이게 된다. 이 연구에서는 굴착직후 짧은 시간 동안에서 공동주변에서 발생하는 응력재분포와 공극수압변화 양상을 수치해석적으로 검토하였다. 공극수압을 고려하지 않는 탄성해석과는 달리 굴착직후 짧은 시간동안에는 공동 벽면의 직후방에서 최대접선응력이 형성되고 있음을 확인할 수 있었다.

• Geomechanics and Engineering
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• 제8권3호
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• pp.323-359
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• 2015

This paper presents an elasto-plastic model for determination of the ground response curve of a circular underwater tunnel excavated in elastic-strain softening rock mass compatible with a nonlinear Hoek-Brown yield criterion. The finite difference method (FDM) was used to propose a new solution to calculate pore water pressure, stress, and strain distributions on periphery of circular tunnels in axisymmetric and plain strain conditions. In the proposed solution, a modified non-radial flow pattern, for the hydraulic analysis, is utilized. To evaluate the effect of gravitational loads and variations of pore water pressure, the equations concerning different directions around the tunnel (crown, wall, and floor) are derived. Regarding the strain-softening behavior of the rock mass, the stepwise method is executed for the plastic zone in which parameters of strength, dilatancy, stresses, strains, and deformation are different from their elasto-plastic boundary values as compared to the tunnel boundary values. Besides, the analytical equations are developed for the elastic zone. The accuracy and application of the proposed method is demonstrated by a number of examples. The results present the effects of seepage body forces, gravitational loads and dilatancy angle on ground response curve appropriately.

• 식물병연구
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• 제7권1호
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• pp.49-55
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• 2001

남부 시설재배지에서 서식하는 뿌리혹선충의 종류와 race를 조사하고 그들에 대한 간이동정법을 제시하였다. 남부 시설재배지에는 Meloidogyne arenaria race 2(59%), M. incognita race 1(23%), M. incognita 미동정 race(18%)가 분포하고 있었음, 우점종은 땅콩뿌리혹선충(M. arenaria) race 2 였다. 유충의 길이는 M. arenaria가 411$\mu\textrm{m}$(306-503$\mu\textrm{m}$), M. incognitark 384$\mu\textrm{m}$(312-488$\mu\textrm{m}$)로 두 종의 범위가 겹치고 있어 종 동정에 참고하기 어려웠으며, M. arenaria와 M. incognita의 종 동정에 가장 쉽게 이용할수 있는 특징은 암컷의 머리에 있는 Excretory pore 위치였다.

• Composites Research
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• 제25권1호
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• pp.1-8
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• 2012

본 논문에서는 다공성 복합재료의 열탄성 거동 예측을 위하여 미시역학적 유한요소 해석을 통해 기공 탄성 인자를 측정하였다. 먼저 기공 압력에 의한 복합재료의 응력 및 변형 상태를 기술하기 위해서 구성 방정식에 기공 탄성 인자를 도입하였다. 기공 탄성 인자의 산출에 필요한 기공 압력에 의한 팽창 변형도와 기공 형성에 따른 균질화 탄성 계수의 저하를 측정하였다. 기공의 형상, 크기, 배열 형태에 따른 이차원 대표 체적 요소의 모델링과 유한요소 해석을 수행하였다. 기공도, 재료 이 방성이 기공 탄성 인자에 미치는 영향과 기공 압력에 따른 변형 에너지 밀도 분포를 살펴보았다. 또한, 측정된 기공 탄성 인자의 유용성을 검토하기 위하여 탄소/페놀릭 복합재료의 열탄성 거동을 예측하였다.

• 콘크리트학회논문집
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• 제11권4호
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• pp.31-41
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• 1999

Blended Low Heat type cement is ground granulated blast furnace slag and fly ash mixed ternary with ordinary portland cement. From the viewpoint of X-ray patterns of domestic LHC, the main components of cement such as $C_2$S, $C_3$A, $C_3$S are considerably reduced. Therefore the heat evolution of LHC paste is 42cal/g lower than of OPC paste. At early age, the compressive strength development of LHC concrete is delayed, but the slump loss ratio of fresh concrete is reduced more than 20% with elapsed time. The penetrability of LHC is lower than that of OPC by 1/7.8 with the penetrability of chloride ion into the concrete until the age of 120 days. And the PD Index value of LHC is 0.44$\times$10-6 $\textrm{cm}^2$/s, which indicates only 39.3% of OPC. From the Mercury Intrusion Porosimetry test of cement past, we know that the pore size of LHC is more dense than that of OPC by production of C-S-H.

• 한국생산제조학회지
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• 제18권6호
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• pp.697-701
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• 2009

A simple method for the fabrication of porous nano-master for the anti-reflection effect on the transparent substrates is presented. In the conventional fabrication methods for antireflective surface, coating method using materials with low refractive index has usually been used. However, it is required to have a high cost and long processing time for mass production. In this paper, we developed a porous nano-master with anti-reflective surface for the molding stamper of the injection mold, hot embossing and UV imprinting by using the aluminum anodizing process. Through two-step anodizing and etching processes, a porous nano-master with anti-reflective surface was fabricated at the large area. Pattern size Pore diameter and inter-pore distance are about 130nm and 200nm, respectively. In order to replicate anti-reflective structure, hot embossing process was performed by varying the processing parameters such as temperature, pressure and embossing time etc. Finally, antireflective surface can be successfully obtained after etching process to remove selectively silicon layer of AAO master.