• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.234-237
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• 2000

In this paper, the structural, dielectric and piezoelectric properties of the Pb[(S $b_{1}$2/N $b_{1}$2/)$_{0.035}$- $_Mn_{1}$3/N $b_{2}$3/)$_{0.065}$-(Z $r_{0.49}$, $Ti_{0.51}$)$_{0.90}$] $O_3$ ceramics were investigated with respect to the variation of the milling time. Grain size was decreased as the increase of milling time. As the milling time is increased, the particle size of the powder was decreased. Dielectric constant and electromechanical coupling factor (Qm)were slowly increased with the increase of milling time. The highest value of Qm was 1,497 at milling time 8 hour. Temperature coefficient of resonant frequency(TC $F_{r}$) was moved to positive side with the increase of milling time.e.e.e.e.e.e.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.477-479
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• 2008

Drawability and other mechanical properties of sheet metals are strongly dependent on their crystallographic orientations. In this paper the formability of the AA 5052 Al alloy sheets was investigated after asymmetric rolling and subsequent heat treatment. In most cases, after asymmetric rolling specimens showed a fine grain size and subsequent heat treated specimens showed that the ND//<111> texture component were observed. The anisotropy of formability is often described by the plastic strain ratios (r-value) as a function of the angle to the rolling direction in sheet metal. For a good formability, a high r-value is required in sheet metals. In the asymmetry rolled and subsequent heat treated Al alloy sheet, the variation of the plastic strain ratios have been investigated in this study. The plastic strain ratios of the asymmetry rolled and subsequent heat treated AA 5052 Al alloy sheets were higher than those of the original Al sheets. These could be related to the formation of ND//<111> texture components through asymmetric rolling in Al sheet.

• 한국지형학회지
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• 제25권3호
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• pp.19-42
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• 2018

In this study, we surveyed weathering progressing aspect by major elements variation and rock hardness by using XRF analysis, schmidt hammer, and thin section analysis. This observation suggested that the weathering process is likely to develop differently according to microstructural characteristics. R-value on the inside wall are lower than those on the outside. Also, the shadier the environment was, the closer it was to inshore areas, the R-value appeared to be lower. The movement of the elements such as Ca, Na and K shows that feldspar is hydrolyzed and can form salt crystallization like a gypsum or halite when they combine with the elements such as S or Cl. It proved a high CaO, $Na_2O$ and $K_2O$ content on flaking inside wall and rock meal. The exfoliation was mainly observed along the shady backwall and ceiling of tafoni. This helped in predicting the growth of tafoni as well as the direction of its progress.

• STI Policy Review
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• 제3권1호
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• pp.46-62
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• 2012

This study investigates the effects of the two most important indicators of a nation's state of scientific infrastructure: R&D investment and the number of R&D researchers engaged in high-tech product export competitiveness for a panel of 11 countries/economies from East Asia from 1994 to 2010. A GMM panel estimation method was employed to account for the dynamic effect of trade and to control for un-observed country specific effects that may arise due to an inter-country differences and intra-country dynamics. Accordingly, the empirical results reveal that (once controlled for the influence of per capita income) physical capital and infrastructure, a 1% increase in a country's expenditure on the ratio of R&D to GDP may increase high-tech product export performance by approximately $397 million per year. Other factors constant, a 1% increase in the number of R&D researchers is expected to increase the ability to export high-tech products by approximately $67 million. The East Asian development experience demonstrates how latecomers can follow systematic industrialization and join the handful of economies that have come a long way toward closing the knowledge gap with the global technological leaders. However, this does not mean that the policy approaches and overall commitments pursued by each East Asian economy in relation to R&D investment and acquisition of an adequate pool of researchers, and their ultimate achievements in high-tech product export competitiveness were uniform. As a result, there is still a significant variation among countries/economies in terms of performance. This study recommended a number of potential tools and policy instruments that may assist policy makers to foster R&D as an engine to enhance the high-tech product export competitiveness.

• 한국전문물리치료학회지
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• 제19권1호
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• pp.76-85
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• 2012

The purpose of this study was to identify the factors determining the participation restriction of chronic stroke patients based on international classification of functioning, disability, and health (ICF) model. Sixty-eight stroke patients participated. The participants were assessed participation restriction using the Korean version of London handicap scale (K-LHS), modified Barthel index (K-MBI) to measure activities of daily living, Berg balance scale (K-BBS) to assess balance, and the center for epidemiologic studies depression (K-CES-D) to gauge depression. Also, 3 minutes walking test (3MWT), gait velocity, asymmetric posture, and family support were assessed. A stepwise multiple regression analysis was used to explore the factors determining participation restriction. There were no significant different in the K-LHS and K-MBI results by gender (p>.05). Correlations between the K-LHS and K-MBI (r=-.656), K-BBS (r=-.543), K-CES-D (r=.266), 3MWT (r=-.363), gait velocity (r=.348), and family support (r=-.389) were significant (p<.05). Also, the K-MBI and family support were the factors that determined participation restriction (p<.05) and that 40.2% of the variation in the K-LHS can be explained. Therefore, it is suggested that evaluation and intervention of patient's activity level and extent of family support is necessary to reduce participation restriction of chronic stroke patients.

• 한국인터넷방송통신학회논문지
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• 제18권2호
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• pp.55-62
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• 2018

VANET은 급격히 부상하고 있는 서비스 영역으로 수 ms 수준의 엄격한 latency 요구사항을 가진다. 이러한 수준의 낮은 latency를 보장하기 위해 latency가 보장되면서 coordinator에 의한 scheduling 없이 join/leave가 자유로운 Autonomous TDMA(ATDMA)가 제안된 바 있다. 본 연구에서는 hidden node, 채널 페이딩, 노드 밀집도 변이 등이 존재하는 non-perfect decoding 환경에서 동작하도록 ATDMA를 확장한 ATDMA revision(ATDMA-R)을 고안하였다. 또한 시뮬레이션을 통해 ATDMA와 ATDMA-R의 성능을 비교하여 ATDMA 대비 ATMDMA-R이 다양한 실제적 환경에서 강인성을 보이는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1623-1624
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• 2006

It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.

• 한국균학회지
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• 제32권1호
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• pp.1-7
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• 2004

본 연구는 망태버섯속(Dictyophora species) 균의 종 구분을 위하여 국내수집 5균주와 국외도입 6균주에 대한 rDNA ITS 영역의 PCR-RFLP 및 염기서열을 분석하였다. 그 결과, ASI 32001, 32003, 32005, 32006, 32011이 D. indusiata, ASI 32002, 32007, 32008, 32010이 D. echinovolvata, 그리고 ASI 32004와 Phallus rugulosus ASI 25007은 같은 군으로 그룹화 되었다. 이 결과는 기존에 조사된 배양온도, 배지pH, 선택배지 등 배양적 특성과 재배적, 형태적 특성에 의한 구분과 일치하는 경향이었다. 따라서 rDNA ITS 영역의 PCR-RFLP 및 염기서열분석은 Dictyophora속 보존균주의 종 구분에 있어서 선행적, 보충적 수단으로 활용하기에 충분하다고 판단된다.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.49-59
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• 2008

The effects of design parameters on the pellet transport rate in the ejector system which is widely used in the production processes of automotive parts were investigated experimentally. The primary nozzle geometry, the area ratio (R) of nozzle exit cross-sectional area to mixing chamber cross-sectional area and the distance (S) from primary nozzle exit to mixing chamber entrance were considered as the design parameters. The area ratios of the primary nozzle were varied from R=0.10 to R=0.25, 0.30, 0.40 and 0.55. The primary nozzle was positioned at the non-dimensional distance (S/D) of 1.30, 1.87, 2.44, 3.00 and 3.75, normalized using the mixing chamber diameter (D). The design parameters were determined to run with high efficiency by measuring the pellets transport rate. The geometry and the area ratio (R) of the primary nozzle had an effect on the pellet transport rate of the ejector system, and the area ratio of R=0.3 was carefully selected after taking the minimum fluidization velocity and transport rate of applied pellets into account. The higher pellet transport rate with the variation of the distance (S/D) was observed at S/D of 2.44.

• 수산해양교육연구
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• 제9권2호
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• pp.179-187
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• 1997

경상대학교 해양과학대학 실습선 경양호 기관의 회전수와 추진기의 핏치각을 전속(全速)(R.P.M. 680, P.A. $18^{\circ}$), 반속(半速)(R.P.M. 640, P.A. $16^{\circ}$), 미속(微速)(R.P.M. 580, P.A. $10^{\circ}$)의 상태로 하고, 이들 각각에 따른 시험선의 트림을 2.45m, 2.15m, 1.45m 선미 트림으로 조정하여 마일 포스트를 왕복하여 도플러 로그의 대지 속력과 실속력을 측정하여 비교 분석한 결과 도플러 로그 지시속력은 트림의 변화에 큰 영향을 받았으나 속력에는 그다지 큰 영향을 미치지 않음을 알 수 있었다. 한편 세 경우 모두 선의 트림이 2.15m 선미 트림 일때 속력 변화의 폭과 오차가 가장 적어 선체가 안정되고, 트림의 순간적 변화가 적으므로 최적의 상태라 할 수 있다. 그리고 미속 전진중 일때 속력 변화의 폭이 가장 크게 나타났는데 이것은 마일 포스트 사이를 통과 하는데 소요되는 시간이 전속, 반속 전진중 일때 보다 많이 소요되므로 그 간에 외력의 영향을 많이 받았기 때문이라 추정되었다. 특히 세 경우 모두 처음 마일 포스트를 통과한 후 약 30초 사이에는 도플러 로그의 지시속력이 저속임과 동시 속력 변화의 폭이 아주 크게 되었다가 그 후는 완만한 속력 변화를 보였는데 이러한 원인은 기관의 회전수와 핏치각을 변화시킨 후 최적의 상태가 되기 이전에 마일 포스트를 통과한 때문이라 생각된다.