• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.17-24
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• 2004

Surrface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

• 공업화학
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• 제17권3호
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• pp.291-295
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• 2006

본 연구에서는 아임계 및 초임계 이산화탄소하의 에틸 아세토아세테이트의 케토-에놀 토토머릭 평형상수를 후리에 적외선 분광기를 이용하여 세 가지 다른 온도에서 측정하였다. 케토-에놀 토토머릭 평형상수의 용매에 대한 밀도 의존성을 연구하기 위하여 정온하에서 이산화탄소의 압력을 변화시켰다. 용매인 이산화탄소의 밀도를 증가 시키면, 케토 토토머의 양이 증가하게 되어 케토-에놀 토토머릭 평형상수값이 감소한다. 에틸 아세토아세테이트의 케토-에놀 토토머릭 평형상수의 밀도의존성을 연구하기 위하여 변형된 격자유체수소결합 모델을 적용하였다.

• 한국환경과학회지
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• 제7권2호
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• pp.223-232
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• 1998

득량만의 조석주기에 따른 성층특성을 연구하기 위하여 우선 30여개 관측점에서 관측된 수온, 염분, 밀도, 해류, 열수지, 바람, 밀도류 자료를 조사하였다. 이 관측자료를 토대로 성층현상을 규명할 수 있는 해석적 모델을 개발하였으며 이 해석적모델을 이용하여 얻어진 연구결과에 따르면, 득량만의 성층을 이루는 요인은 조석, 태양열, 밀도,류인 것으로 나타났으며, 성층을 파과할 수 있는 조석에너지의 혼합에너지의 에너지 기여율 $\varepsilon$ 은 약 0.020 - 0.021정도 되는 것으로 나타났다.

• 한국소음진동공학회논문집
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• 제22권5호
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• pp.429-436
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• 2012

In concert halls and auditoriums, acoustic reflector and stage enclosure is one of the main factors on the room and stage acoustic characteristics. As a stage enclosure and acoustic reflector honey comb based light-weight reflector is widely used, because it is easy to install. However, there was not enough research on the surface density effect on room and stage acoustics. In this study, sound absorption coefficient tests on three kinds of wooden acoustic reflectors with different surface density were conducted. Surface density of acoustic reflector was changed from 11 kg/$m^2$ to 41 kg/$m^2$. For the low frequency excitation, sub-woofer was used with omnidirectional loud-speaker simultaneously. From the experiments, it was found that sound absorption coefficient below 250 Hz band was decrease by the increment of surface density. In order to check the influence of the surface density on room and stage acoustic parameters, room acoustic simulation was conducted with sound absorption coefficients, which were tested in reverberation chamber. By the increment of surface density of acoustic reflector, RT(reverberation time) and EDT(early decay time) were increased. Also, ST(stage support) was improved in low frequency bands.

• 한국인쇄학회지
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• 제14권2호
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• pp.21-36
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• 1996

With increased use of halftone dot overprints for offset color printing, it is important to study the density and ink trap of the overprints. In this research the equation to predict the density and the method to evaluate ideally the fractional ink trap are preposed. And also the halftone dot overprinting experiments of Magenta over Cyan or Cyan over Magenta under wet-on-wet or wet-on-dry overprinting using 2-color offset press show the above proposals are reasonable, and show the effect of overprinting sequence on the density and ink trap.

• 한국표면공학회지
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• 제29권6호
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• pp.876-879
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• 1996

The effect of oxygen vacancy and Sn donor on carrier density for Indium Tin oxide (ITO) and Indium oxide (InO) films has been investigated. Hot-cathode Penning discharge sputtering (HC-PDS) in the mixed gasses of argon and oxygen was applied to fabricate the ITO and InO films. Density of oxygen vacancy was estimated using a high-energy ion beam technique. The electrical properties of the films such as resistivity, carrier density and mobility were estimated by Van der Pauw method. The doping efficiency of oxygen vacancy could be obtained from the relationship between oxygen vacancy and carrier density. The doping efficiency of oxygen vacancy for ITO films resulted in a quite small value. Comparing the doping efficiencies of ITO and InO films, the effect of Sn donor on carrier density was also discussed.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.115-124
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• 2002

The optimum design of auto-catalyst needs a good compromise between the pressure drop and flow distribution in the monolith. One of the effective methods to achieve this goal is to use the concept of radially variable cell density. However, there has been no study of evaluating the usefulness of this method on light-off catalyst. We have computationally investigated the effectiveness of variable cell density technique applied to the light-off catalyst using a three-dimensional integrated CFD model. in which transient chemical reacting calculations are involved. Computed results show that variable cell density technique can reduce the accumulated emissions of CO and HC during the early 100sec of FTP cycle by 86.78 and 80.87%, respectively, The effect of air-gap between the monoliths has been also examined. It is found that air-gap has a beneficial effect on reducing pressure drop and cold-start emissions.

• 대한기계학회논문집A
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• 제29권3호
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• pp.411-417
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• 2005

Surface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.

• 한국초지조사료학회지
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• 제18권1호
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• pp.49-54
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• 1998

This experiment was carried out to investigate effect of plant density on yield and quality of corn at the forage experimental field, grassland and forage division, National Livestock Research Institute, RDA, Suwon eom 1996 to 1997. The two corn hybrids, P 3352 and G 4743, were grow at plant density of 67,000; 71,000; 83,000 ; 89,000 and 95,000 plantha in 60,70 and 75-an spaced rows. At the low density, plant and ear height were decreased but ear length and weight were increased. Plant density had little effect on the tasseling date, silking date and ear ratio to total dry matter. The total dry matter yield of two hybrids was increased kom 15,294 to 18,996 in P 3352 hybrid and 15,881 to 21,386kglha in G 4743, respectively, by decreasing plant density. Plant density had little effect on the ADF(acid detergent fiber), NDF (neutral detergent fiber) and CP(crude protein) concentrations, but the quality of late maturity hybrid, G 4743, was higher than that of early maturity hybrid, P 3352. The result of this study indicate that 67,000 plantlha plant density was recommendable for machanization and maximum DM yield of corn.

• 한국세라믹학회지
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• 제41권8호
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• pp.588-592
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• 2004

Dynamic Milling (DM) 방법에 의한 $UO_2$ 분말의 특성 변화가 밀도에 미치는 영향을 조사하였다 분쇄시간(0∼8시간)의 증가에 따라 분말입자의 크기는 감소하며 둥근 형태를 지녔으며, 비표면적과 O/U 비는 증가하였다. 이러한 특성 변화에 의해 성형밀도는 증가한 반면에, 소결밀도는 감소하는 경향을 보였다. 소결밀도의 감소는 분말 분쇄과정에서 야기된 $UO_2$ 분말의 O/U 비의 증가가 주된 영향을 미친 것으로 사료된다.