• 한국작물학회지
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• 제68권1호
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• pp.1-7
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• 2023

벼 품종별 재식밀도 변경 시 생육특성 변화를 분석한 결과는 다음과 같다. 1. 재식밀도 변경 시 간장, 수장의 변화는 없으며 각 포기 사이의 재식거리가 10 cm 넓어질수록 포기당 분얼수는 평균 4.4개, 이삭당 립수는 평균 7.5개 증가하였다. 2. 기존 80주 이앙 시 분얼수 및 립수가 많은 품종이 재식밀도가 감소되어도 분얼수 및 립수가 많은 경향이었다. 3. 재식밀도 감소 시 분얼수 및 립수 증가비율은 기존 80주 재배 시 품종의 분얼수 및 립수와 유의한 상관관계를 나타내지 않았다. 4. 재식밀도 감소 시 이삭지경의 개수 및 길이가 증가하였으며 이 때문에 이삭당 립수가 증가한 것으로 판단된다.

• Tribology and Lubricants
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• 제24권6호
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• pp.368-373
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• 2008

This paper will investigate the friction characteristics of a 100m Hexagonal Array, Micro-scale Dimple Pattern, on bearing steel. These characteristics are researched by utilizing a pin-on-disk wear test machine, under various test conditions. The reduction of friction is a necessary requirement for the improved efficiency of this machine. As the speed increases, there is a decrease in the effect of the dimple of friction characteristic, with substantially little change to density. Conversely, as the load increases, the dimple pattern grows larger, resulting in a difference in the texture of these two components. At a dimple density of 10% the friction characteristic is easily demonstrated, with a consistent change in both speed and load.

• 대한토목학회논문집
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• 제29권4D호
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• pp.443-450
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• 2009

A연속류도로는 교통량-속도-밀도 간에 상호 밀접한 관계가 있기 때문에 연결로교통류가 본선에 합류하게 되면 속도나 밀도가 변할 뿐만 아니라 이들 간의 상관관계를 나타내는 모형식도 달라진다. 따라서, 본 연구는 합류영향권역에서 시공간적으로 연속된 교통자료를 이용하여 속도-밀도 변수간의 상관관계 변화구간을 파악하고, 구간별 변화내용을 분석하였다. 분석결과, 상류 및 합류구간에서는 "Underwood"모형의 지수형태를 보이며, 합류구간을 통과한 하류구간에서는 "Greenshields"모형의 직선형태를 나타내었다. 속도-밀도 상관관계가 변화된 하류변화구간은 연결로와 접속한 3차로의 합류 종점부를 기점으로 하류 100m~500m 범위에서 내측차로로 갈수록 점차 하류방향으로 이동하는 현상을 보였다. 또한, 상류구간, 합류구간, 하류변화구간은 속도-밀도 모형에서 자유속도(상수)와 혼잡밀도에 대한 자유속도비(기울기)가 통계적으로 서로 다른 이질적인 교통류로 나타났다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.205-208
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• 2002

Thermal design is required with considering thermal stability to verify the reliability of electric power device with using IGBT. Numerical analysis is performed to analyzed the change in thermal resistance with respect to the various thermal density of heating element. Correlations between thermal resistance and heat generation density are established. With using these correlations, performance curve is composed with respect to the change in thermal resistance of cooling conditions for natural convection and forced convection. Thermal fatigue is occurred at the Inside and outside of IGBT by repeated heat load. The crack is occurred between base plate and ceramic substrate for the inside. When the crack length is 4mm, the failure is occurred. Therefore, Thermal design method considering thermal density, thermal fatigue resistance is presented on this study and it is expected to thermal design with considering life prediction.

• 한국표면공학회지
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• 제16권1호
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• pp.3-9
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• 1983

The change of the hardness and yield strength depending upon the electrolysis conditions was investigated for Watts and bright nickel electrodeposits. The hardness of Watts nickel electrodeposits decreased with increasing current density in the range of 1-15A/Am2, while it increased with increasing bath temperature. The hardness of bright nickel deposits increased noticebly in comparison with that of Watts nickel electro-deposits. The hardness and the yield strength of the bright nickel electrodeposits increased considerably with decreasing current density and the highest value was obtained at the lowest current density (1A/dm2), while they decreased noticebly at the bath temperature of 80$^{\circ}C$ in comparison with that of 40-60$^{\circ}C$. The change of the hardness and the yield strength of bright nickel electrodeposits depending upon the electrolysis conditions could be mainly attributed to the variation of organic additives codeposited in the electrodeposits. The recrystallizatioin temperature(50% softening temperature) of the Wattss and the bright nickel electro-deposits was 520-280$^{\circ}C$ and 350-410$^{\circ}C$ respectively and then the recystallization temperature of bright nickel deposits was lower than that of the Watts nickel electrodeposits.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1166-1174
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• 2000

This work presents a two-dimensional quasi-steady state model to study the fluid flow and heat transfer in high-power density welding process of thin AISI-304 stainless steel plates. The enthalpy method and the finite volume method were used for a numerical analysis of the mushy region phase change as well as the heat flow at the weld pool and the heat-affected zone. The results show that the mushy region distributed around the weld pool becomes wider downstream and the surface heat losses by convection and radiation can be significant factors in welding process especially when a welding speed is relatively low.

• 한국세라믹학회지
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• 제50권3호
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• pp.180-185
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• 2013

We investigated the characteristics of hot-pressed pure yttria ceramics, and annealed them in an oxidation atmosphere. Regardless of the heat treatment in the oxidation atmosphere, XRD analysis showed that all the samples had a $Y_2O_3$ phase without structural change. Even though the color variation of the hot-pressed $Y_2O_3$ ceramics was due to the sintering temperatures, the oxidation process turned the color of the $Y_2O_3$ ceramics into white. The color change during oxidation treatment appears to be related to oxygen defects. In addition, oxygen defects also affected the weight change and microstructure of the $Y_2O_3$ ceramics. The $Y_2O_3$ ceramic sintered at $1600^{\circ}C$ had a $5.03g/cm^3$ density, which is close to the theoretical density of $Y_2O_3$. As the sintering temperature increased, small homogeneous grains grew to large grains which affected the Vickers hardness. $Y_2O_3$ ceramics hot-pressed at $1600^{\circ}C$ and annealed at $1200^{\circ}C$ had a flexural strength of 140MPa.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.30.4-31
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• 2008

Formation of longitudinally wave-like plasma density structure in the low-latitude F region is now a well-known phenomenon from the extensive studies in recent years. Observations of plasma density from multiple satellites have shown that the locations of the crests of the plasma density that are seen to be stationary during daytime are shifted after sunset. This phenomenon has been understood to be caused by eastward drift of the ionosphere at night. However, the eastward drift velocity of the ionosphere after sunset is not sufficiently large enough to explain the day-night difference in the longitudinal density structure. The just after sunset and the nighttime ionospheric morphologymay be affected by this drift after sunset. In this study, we will investigate the temporal variation of the phase of the longitudinal density structure and vertical plasma drift by analyzing the ROCSAT-1, TIMED/GUVI, and DMSP data and verify the role of the vertical drift after sunset in the change of the phase of the longitudinal density structure.

• 대한기계학회논문집B
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• 제33권6호
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• pp.454-460
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• 2009

To analyze the mixture formation process of evaporating diesel spray is important for emissions reduction in actual engines. Then the effects of change in density of ambient gas on spray structure in high temperature and pressure field have been investigated in this study. The ambient gas density was changed from ${\rho}_a=5.0kg/m^3$ to ${\rho}_a=12.3kg/m^3$ with CVC(Constant Volume Chamber). Also, simulation study by modified KIVA-II code was conducted and compared with experimental results. The ambient temperature and injection pressure are kept as 700K and 72MPa, respectively. The images of liquid and vapor phase in the evaporating free spray were simultaneously taken by exciplex fluorescence method. As experimental results, with increasing ambient gas density, the tip penetration of the evaporating free spray decreases due to the increase in the drag force from ambient gas. The spatial structure of a diesel spray can be verified as 2-regions consisted of liquid with momentum decrease and vapor with large-scale vortex. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

• 생물환경조절학회지
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• 제24권3호
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• pp.173-177
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• 2015

본 시험은 여주의 봄 무가온 하우스내 입체재배시 적정 재식밀도를 구명하고자 수행하였다. 재식밀도는 $235plants{\cdot}10a^{-1}$, $305plants{\cdot}10a^{-1}$, $380plants{\cdot}10a^{-1}$의 3처리로 하였으며 '에라부' 품종을 이용하여 3월 26일 정식하였다. 유인방법은 어미 줄기를 적심하고 아들 줄기를 6개로 유인하였다. 시설 내 광도는 재식밀도가 높을수록 낮아졌으며 순 광합성율도 41-71% 정도로 유의하게 낮았다. 재식밀도에 따른 과일 특성에서는 차이를 보이지 않았으나 재식밀도가 낮을수록 주당 근중과 수확 과수는 증가하였다. 평균 과중은 $305plants{\cdot}10a^{-1}$ 처리구에서 338.7g으로 가장 무거웠으며 $235plants{\cdot}10a^{-1}$ 처리구에서 285.2g으로 가장 가벼웠다. 총 수량은 $305plants{\cdot}10a^{-1}$ 처리구에서 $5,393kg{\cdot}10a^{-1}$로 가장 많았으며 $235plants{\cdot}10a^{-1}$ 처리구에 $4,068kg{\cdot}10a^{-1}$로 가장 적었다. 상품과의 수량도 $305plants{\cdot}10a^{-1}$ 처리구에서 $4,767kg{\cdot}10a^{-1}$으로 재식밀도 $235plants{\cdot}10a^{-1}$에 비하여 24%, $380plants{\cdot}10a^{-1}$에 비하여 13% 정도가 증가되었다. 따라서 무가온 하우스내 입체 재배시 적정 재식밀도는 $305plants{\cdot}10a^{-1}$ 정도가 적당할 것으로 판단된다.