• 한국지형학회지
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• 제28권3호
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• pp.27-35
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• 2021

This study tried to reveal incision rate and its change by formation of lava plateau in the Cheorwon-Jeongok area. Incision rates of 0.421 m/ka and 0.101 m/ka in the upper and lower reaches of Hantan-gang, respectively, were calculated from sites before formation of lava plateau. These incision rates indicate that the upper and lower reaches of Hantan-gang have much higher and slightly lower incision rates than streams with similar distances from the Taebaek Mountains. However, sites after formation of lava plateau mostly showed incision rates ranging from 0.5 m/ka to 0.9 m/ka. Streams flowed on the lava plateau revealed 2-3 times higher incision rates than unrelated-streams or paleo-streams to formation of lava plateau did. These results suggest that incision rate in the study area was greatly influenced by formation of lava plateau and resultant geomorphic avulsion with rearrangements of stream.

• Bulletin of the Korean Chemical Society
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• 제26권7호
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• pp.1037-1043
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• 2005

Kinetic study on the cleavage of N-methylphthalamic acid (NMPA) in mixed acidic aqueous-acetonitrile solvent reveals the formation of both phthalic anhydride (PAn) (through O-cyclization) and N-methylphthalimide (NMPT) (through N-cyclization). The formation of NMPT varies from $\sim$20% to $\sim$3% with the increase in the content of acetonitrile from 2 to 70% v/v. Pseudo first-order rate constants for the formation of PAn are more than 4-fold larger than those for the formation of NMPT at 2% v/v $CH_3CN$ in mixed aqueous solvents. Pseudo first-order rate constants for alkaline hydrolysis of NMPT reveal a nonlinear decrease with increase in the content of $CH_3CN$ in mixed aqueous solvents.

• Tribology and Lubricants
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• 제14권4호
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• pp.108-113
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• 1998

In order to investigate the characteristics of top ring groove deposit formation in diesel engine, engine test and simulation test were performed. From component analysis of used oils sampled from actual running engines, soot content in engine oil was selected as a main parameter for evaluating oil degradation. Deposit formation is highly related to soot content in lubricating oils. And high soot content oil accelerates deposit formation even in low temperature region below 26$0^{\circ}C$. In low temperature region below 26$0^{\circ}C$, deposit formation rate is mainly affected by top ring groove temperature. However, in high temperature region above 26$0^{\circ}C$, deposit formation rate is affected by soot content as well as top ring groove temperature. Therefore, soot content as well as top ring groove temperature should be kept a certain level in order to prevent troubles due to carbon deposit formation.

• 농업과학연구
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• 제47권4호
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• pp.987-993
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• 2020

This study investigated the effective harvest of 'Kyoho' grapevines by examining their characteristics including bud development, necrosis types and flower primordium formation. The size of the axillary bud did not show any difference in the 5th node or more, but it was smaller because it was closer to the base in the 4th node or less. In the 1st node, the rates of main bud necrosis (MBN), accessory bud necrosis (ABN), and whole bud necrosis (WBN) were high, and the rate of flower primordium formation was low, but there was no significant difference in the other nodes. Therefore, it was expected that using other nodes than the 1st node would be advantageous to secure production. Because the growth progresses after sprouting, the main bud necrosis rate increases, showing a very low flower primordium formation rate in March of the following year. Therefore, a method is needed to increase the storage nutrients in the winter and the rate of flower primordium formation after March. This study found that the thickness of the shoots should be less than 8.5 mm between the 3rd and 4th nodes, and the length should be less than 60 cm for nodes up to the 10th node.

• 한국대기환경학회지
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• 제18권2호
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• pp.149-159
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• 2002

The objective of this study was to evaluate the formation characteristics of CBs and CPs from TCE, aliphatic compound. The experiment was carried out in a fixed reactor during 30 min under the oxidation condition at the range of temperature, 300~$700^{\circ}C$. MSWI fly ash was used as catalyst in this study. Total amount of CBs formed greater magnitude than that of CPs overall range of reaction temperature. It is proposed that the formation of CPs was caused from hydroxylation of CBs. According to increasing temperature to $600^{\circ}C$, the yield of CBs and CPs increased but significantly decreased at $700^{\circ}C$. It is suggested that decomposition rate was faster than formation rate at the high temperature. In the homologue distribution of CBs, DCBs were major products at 30$0^{\circ}C$ and the amount of higher chlorinated compound increased to $600^{\circ}C$. Because they were formed by chlorination of lower chlorinated compounds. In case of CPs, the amount of DCPs was 90% of total amounts in both thermal formation and catalytic reaction. On the other hand it was clearly observed that the chlorination rate in catalytic reaction was higher than in thermal formation with TCE only.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1534-1539
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• 2004

This experiment has been carried out to measure the process of droplet formation between water phase fluid(PVA 3%) and organic phase fluid(oil) and vector fields measured by a Dynamic Micro-PIV method in the inside of a droplet while generated. Droplet length controlled by changing flow rate conditions in microchannel. Water-in-oil(W/O) droplets successfully generated at a Y junction and cross microchannel. But oil-in-water(O/W) droplets could not be formed at a Y junction microchannel. That is, PVA 3% flow could not be detached from the PDMS surface and ran parallel with oil flow. When PVA 3% flow rate was constant, droplet length and time period decreased as oil flow rate increased, but droplet frequency increased. When PVA 3% and oil flow rate ratio was constant, droplet length and time period decreased as flow rate increased, but droplet frequency increased. All that case, Standard deviation of droplet formation have less than 5% at averaged droplet length and regular-sized droplets were reproducibly formed.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.42-50
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• 2001

In this paper, the effects of scale formation in engine water jacket upon the thermal durability of engine itself and its component parts were studied. To understand the effect of quality of water, a full load engine endurance test for 50 hours was carried out with not-treated underground water. The followings were found through the tested engine inspection after the endurance test; 1-2 mm thick scale formation in the engine water jacket, valve seat wear, piston top land scuffing, piston pin stick, and cylinder bore scuffing in siamese area. In order to understand the causes of above test results, the heat rejection rate to coolant, the metal surface temperature of combustion chamber, and the oil and exhaust gas temperatures were measured and analyzed. The scale formed in the engine water jacket played a role as thermal insulator. The scale formed in the engine reduced the heat rejection rate to coolant and it caused to increase the metal surface temperature. The reduced heat rejection rate to coolant increased the heat rejection rate to oil and exhaust gas and increased the oil and exhaust gas temperature. Also, the reasons of valve seat wear, piston top land scuffing and cylinder bore scuffing, and piston pin stick quantitatively analyzed in this paper.

• 농업과학연구
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• 제19권1호
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• pp.33-39
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• 1992

Chitin합성 저해제인 buprofezin이 Coriolous versicolor, Ganoderma lucidum, 및 G. applanatum 균사의 생장과 원형질체 나출 및 재생에 미치는 영향을 조사한 결과 buprofezin은 C. versicolor, G. lucidum 및 G. applanatum의 균사생장을 심히 저해하였고 첨가농도가 높을수록 균사생장 억제가 심하였다. Buprofezin처리에 의하여 기균사 및 oidia 형성량은 증가하였으나 균사의 형태에는 변화가 없었다. G. applanatum은 buprofezin 처리에 의하여 원형질체 나출량과 재생율이 현저히 증가하였으나, G. lucidum은 원형질체의 나출량과 재생율이 감소하는 경향을 보였으며 C. versicolor의 경우에는 원형질체 나출량이 증가하였으나, 재생율은 무처리와 차이를 보이지 않았다.

• 한국재료학회지
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• 제18권2호
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• pp.73-76
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• 2008

[ $SF_6$ ] gas has been widely used as an insulating, cleaning and covering gas due to its outstanding insulating feature and because of its inert properties. However, the global warming potential of $SF_6$ gas is extremely high relative to typical global warming gases such as $CO_2$, CFCs, and $CH_4$. For these reasons, it is necessary to separate and collect waste $SF_6$ gas. In this study, the effects of a surfactant (Tween) on the formation rate of $SF_6$ gas hydrates were investigated. The $SF_6$ gas hydrate formation rate increased with the addition of Tween and showed a nearly 6.5 times faster hydrate formation rate with an addition of 0.2 wt.% Tween compared to an addition of pure water. This is believed to be due to the increased solubility of $SF_6$ gas with the addition of the surfactant. It was also found that $SF_6$ gas hydrate in the surfactant solution showed two-stage hydrate formation rates with a formation rate that increased rapidly in the 2nd stage.

• 천문학회보
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• 제41권2호
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• pp.29.4-29.4
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• 2016

The relations between star formation and properties of molecular clouds are studied based on a sample of star forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated molecular clouds and dense clumps. Radio continuum and mid-infrared emission were used to determine star formation rates, while 13CO and submillimeter dust continuum emission were used to obtain masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. We also test two specific theoretical models, one relying on the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star forming regions and extragalactic data. The star formation "efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all the molecular gas.