• Journal of Plant Biology
• /
• 제2권1호
• /
• pp.35-42
• /
• 1959

1. 발아시부터 단일, 암기저온 조건하에서는 괴근은 전연 형성되지 않고, 장일조건에서만 괴근이 형성됨. 따라서 장일조건이 고구마괴근 형성에 대한 유도조건 내지 촉진조건임을 알 수 있다. 2. 본실험은 시종 약전광(300W 전구 사용)으로 재배하였기 때문에 동화작용이나 생장이 특히 미약한 상태에서도 괴근이 유도되었다. 따라서 괴근형성에는 동화물질이나 생장보다도 장일조건이 직접적결요인을 이루는 1종자극을 성립하는 것으로 보인다. 3. 장기조건과 단일조건하의 근계가 서로 특이한 상태를 나타냈고 그것은 단일과 장일조건이 이룬 자극과 관계하는 것으로 보인다. 4. 고구마괴근이 장일조건에 유되되는 사실의 생태학적 의의를 고찰함.

• 세라미스트
• /
• 제23권2호
• /
• pp.114-131
• /
• 2020

Fracture in the titanium carbonitride-metal composites occurs by crack propagation through the carbonitride grains or in the interfaces. Thus, intrinsic properties of the carbonitride need to be enhanced and the interfaces should be also modified to coherent structure to strengthen the composites. Especially, interfacial structure can be the main factor to determine the mechanical properties of titanium carbonitride-metal composites because the interfaces between carbonitride grains and metallic phase are weak parts due to heterogeneous nature of carbonitride and metallic phase. In this paper, methodologies for improving the interfacial structure of titanium carbonitride-metal composites are suggested. Total area of the interfaces can be reduced using solid solution type carbonitrides as raw materials instead of a mixture of various carbonitrides in the composites. Also, synthesis of titanium carbonitride-metal composite powders and the low-temperature sintering of the composite powders for short time can be the way for formation of coherent interfaces. The sintering of the composite powders for short time at low temperature can reduce the potential of formation of interfaces by dissolution and precipitation of carbonitride in the liquid metal. As a result of formation of coherent boundaries due to low-temperature and short-time sintering, interfaces between titanium carbonitride grains and metallic phase have the favorable structure for the enhanced fracture toughness. It is believed that the low-temperature sintering of solid solution type composite powders for short time can be the way to improve the low toughness of the titanium carbonitride-metal composites.

• Bulletin of the Korean Chemical Society
• /
• 제6권4호
• /
• pp.186-191
• /
• 1985

The effect of pressure and temperature on the stabilities of the charge transfer complexes of hexamethyl benzene with iodine in n-hexane has been investigated by UV-spectrophotometric measurements. In this experiment the absorption spectra of mixed solutions of hexamethyl benzene and iodine in n-hexane were measured at 25, 40 and $60^{\circ}C$ under 1,200, 600, 1200 and 1600 bar. The equilibrium constant of the complex formation was increased with pressure while being decreased with temperature raising. Changes of volume, enthalpy, free energy and entropy for the formation of the complexes were obtained from the equilibrium constants. The red shift at higher pressure, the blue shift at higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions. In comparison with the results in the previous studies, it can be seen that the pressure dependence of oscillator strength has a extremum behavior in durene as the variation of ${\Delta}H$ or ${\Delta}S$ with the number of methyl groups of polymethyl benzene near atmospheric pressure in the previous study. The shift or deformation of the potential in the ground state and in the excited state of the complexes formed between polymethyl benzene and iodine was considered from the correlation between the differences of the electron transfer energies and the differences of free energies of the complex formation for the pressure variation.

• 한국초전도ㆍ저온공학회논문지
• /
• 제11권1호
• /
• pp.5-8
• /
• 2009

MgO nanodots have been deposited and formed on top of the substrate surface. Mg was sputtered to form the MgO nanodots on the single crystal substrates by rf-sputtering method and followed by heat treatment in the oxygen ambient. The deposition and formation of MgO nanodots have been controlled systematically using the process variables such as substrate temperature, sputtering time, and rf-power. As the substrate temperature increased from the room temperature the density of MgO nanodots decreased. The optimal conditions of MgO nanodots formation using the rf-sputtering was investigated and the maximum density of more than $230/{\mu}m^2$ on single crystal substrates was obtained when the rf-power of 100 watts was applied for 30 seconds at room temperature. The typical size of MgO nanodots was identified to be <160 nm(diameter) and 4-30nm (height) by atomic force microscopy. The modulated surface morphology was examined through surface images and cross-section analysis and discussed for the artificial pinning sites in the superconducting films.

• Geomechanics and Engineering
• /
• 제33권1호
• /
• pp.65-75
• /
• 2023

Recycled concrete aggregate (RCA) is widely used as a construction material in road construction, concrete structures, embankments, etc. However, it has been reported that calcite (CaCO₃) precipitation from RCA can be a cause of clogging when used in drainage applications. An accelerated calcite precipitation (ACP) procedure has been devised to evaluate the long-term geochemical performance of RCA in subsurface drainage systems. While the ACP procedure was useful for the French Drain application, there remained opportunities for improvement. In this study, key factors that control the formation of calcite precipitation were quantitatively evaluated, and the results were used to improve the current prototype ACP method. A laboratory parametric study was carried out by investigating the effects of reaction temperature and time on the formation of calcite precipitation of RCA, with determining an optimum reaction temperature and time which maximizes calcite precipitation. The improved ACP procedure was then applied to RCA samples that were graded for Type I Underdrain application, to compare the calcite precipitation. Two key findings are (1) that calcite precipitation can be maximized with the optimum heating temperature (75℃) and time (17 hours), and (2) the potential for calcite precipitation from RCA is not as significant as for limestone. With the improved ACP procedure, the total amount of calcite precipitation from RCAs within the life cycle of a drain system can be determined when RCAs from different sources are used as pipe backfill materials in a drain system.

• 한국균학회지
• /
• 제9권1호
• /
• pp.7-12
• /
• 1981

앙송이 복토후(覆土後) 재배실온도(栽培室溫度), $CO_{2}$ 및 복토수분함량(覆土水分含量)이 복토층(覆土層)의 균사생장(菌絲生長) 및 자실체(子實體) 형성(形成)과 수량(收量)에 미치는 영향(影響)에 관(關)하여 연구(硏究)한 결과(結果)는 다음과 같다. 1. 복토후(覆土後) 균사(菌絲)의 영양생장(營養生長) 기문중(期聞中) 재배실온도(栽培室溫度)는 $30^{\circ}C$일때 균사생장(菌絲生長)이 가장 빠르고 25, 20, $15^{\circ}C$로 온도(溫度)가 낮아질수록 감소(減少)하였다. 자실체(子實體)의 형성(形成)및 수량(收量)은 $52^{\circ}C$에서 최대(最大)였고 온도(溫度)가 그보다 높거나 낮으면 감소(減少)하는 경향(傾向)이었다. 2. 복토(覆土)의 수분함량(水分含量)은 70%일 때 균사생장(菌絲生長)이 가장 빠르고 수분함량(水分含量)의 감소(減少)에 비례(比例)하여 감소(減少)하였다. 자실체(子責體)의 형성(形成) 및 수량(收量)은 균사생장최적수분함량(菌絲生長最適水分含量)보다 낮은 60%구(區)에서 최대(最大)였다. 3. 복토후(覆土後) 7일간(日間)의$CO_{2}$농도(濃度)가 0.16%일때는 균사생장(菌絲生長) 및 자실체(子實體)의 형성(形成)이 양호(良好)하였으나 $0.5%{\sim}2.0%$에서는 균사생장(菌絲生長)과 자실체형성(子實體形成)이 급감(急減)하였다. 4. 자실체(子叢體)의 개체중량(個體重量)은 재배실온도(栽培室溫度) $20^{\circ}C$, 복토수분(覆土水分) 70%에서 최대(最大)였다.

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
• /
• pp.23-26
• /
• 1998

The domain formation phenomena of {{{{ { LiLbO}_{ 3} }}}} crystals was investigated and the method for the periodic domain formation in {{{{ { LiLbO}_{ 3} }}}} single crystals during growth was proposed in this study. The strees-induced domain formation mechanism was proposed and explained. The strong piezoelectric effect of{{{{ { LiLbO}_{ 3} }}}} at elevated temperature would be the direct driving force for the inversion of the tensile component of the internal stresses can inverse the original direction of the spontaneous polarization.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 춘계학술대회논문집
• /
• pp.53-56
• /
• 2003

The disappearance of continuous yielding and the formation of an extended region in engineering stress-strain curves at tempering temperatures of 673-873K is closely related to the reduction of mobile dislocations during tempering and dynamic recovery during tensile deformation. In addition, the occurrence of discontinuous yielding at tempering temperature above 923K would be attributed to the formation of new strain-free polygonal ferrite grain.

• Tribology and Lubricants
• /
• 제11권5호
• /
• pp.1-9
• /
• 1995

The mechanism of various spherical particles formation from wide range of tribo-systerns is suggested and deduced by the action of micro-explosion on the basis of the thermally-activated wear theory, in which the flash temperature at contact could be reached clearly upto the material molten temperature due to the secondary activation energy from the exothermic reactions involving lubricant thermo-decomposition, metals oxidation, hydrogen reactions and other possible complex thermo-reactions at the contacts. Various shapes of spherical particles generated from the tribosystem can be explained by the toroidal action of micro-explosion accompanied with the complex thermo-chemical reactions at the contact surfaces or sub-surfaces.

• 약학회지
• /
• 제25권4호
• /
• pp.175-179
• /
• 1981

Rheological studies on the gelatin hydrogels were carried out by rheometer. In the temperature range of $32^{\circ}~90{\circ}C$, the viscosities of the gelatin hydrogels were measured. In order to observe the formation of gel structure, the stress-relaxation tests of the creep-curves were investigated. The structure of viscoelastic substance could be considered of a three dimensional crosslinked matrix. As the result viscoelastic coefficients were obtained by Maxwell element, which are correspond to the network structure. From the relationship between the stress-relaxation time and temperature, activation energy correspond to breaking the formation of gels was calculated to be 13.91kcal/mole.