• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.276-276
• /
• 2022

Wheat is one of the most widely grown food crops worldwide. Extreme precipitation and wind disturbances increased due to the abnormal climate, which resulted in increased lodging. Introduction of dwarf genes in wheat significantly increased lodging resistance and productivity in wheat breeding. In this study, we performed the genotyping of dwarfing genes between 'Keumkang' and 'Komac 5' ('Keumkang' mutant). In addition, we investigated the relationship between plant height and several phenotypic characters using F₂ segregation populations derived from crosses between the two varieties. There was no significant difference in phenotypic characters between the two varieties except for plant height. In the genotyping analysis using dwarfing genes, mutations of two dwarfing gene were found to be induced between the two varieties. The four genotypes of the F₂ populations from a crossing between 'Keumkang' and 'Komac 5' were used to compare and evaluate the effects of two dwarfing genes. Plants with two single mutant dwarfing gene and double mutant dwarfing gene revealed reduced plant heights than control plants by 4.5%, 6.9%, and 33.2%, respectively. The phenotype analysis showed that double mutant dwarfing gene affected wheat stem growth as the length decreases from the second node, resulting in decreased plant height. However, there were no significant differences in the agronomic traits between mutant plants and control plant. These results may provide novel information about the effect of double mutant dwarfing gene on plant height, and may help improve lodging tolerance and wheat yield.

• 대한치주과학회:학술대회논문집
• /
• 2002.11a
• /
• pp.91-91
• /
• 2002

• 한국연소학회:학술대회논문집
• /
• 2001.06a
• /
• pp.9-16
• /
• 2001

When large size nozzle with low jet velocity is used, the buoyancy effect arises from the density difference among propane, air, and burnt gas. Flame characteristics in such buoyant jets have been investigated numerically to elucidate the effect of buoyancy on lifted flames. It has been demonstrated that the cold jet has circular cone shape since upwardly injected propane jet decelerates and forms stagnation region. In contrast to the cold flow, the reacting flow with a lifted flame has no stagnation region by the buoyancy force induced from the burnt gas. To further illustrate the buoyancy effect on lifted flames, the reacting flow with buoyancy is compared with non-buoyant reacting flow. Non-buoyant flame is stabilized at much lower height than the buoyant flame. At a certain range of fuel jet velocities and fuel dilutions. an oscillating flame is demonstrated numerically showing that the height of flame base and tip vary during one cycle of oscillation. Under the same condition. non-buoyant flame exhibits only steady lifted flames. This confirms the buoyancy effect on the mechanism of lifted flame oscillation.

• Journal of Navigation and Port Research
• /
• v.27 no.5
• /
• pp.451-458
• /
• 2003

A ship with small metacentric height or high speed vessel performs relatively large roll angles in her manoeuvring motion. Roll coupling effect should be taken into consideration for accurate prediction of manoeuvring motion of such a ship. This paper proposes a new mathematical model of ship manoeuvring motion taking coupling effect of roll into consideration. Some kinds of manoeuvring motion are simulated by computer, based upon the proposed model. The simualted results by proposed model here are compared with those by existing model. The proposed model is found to be practical and useful for prediction of manoeuvring motion with roll effect.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.9
• /
• pp.791-796
• /
• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• Journal of Electrochemical Science and Technology
• /
• v.15 no.1
• /
• pp.132-151
• /
• 2024

Proton exchange membrane fuel cell (PEMFC) has received extensive attention as it is the most common hydrogen energy utilization device. This research not only investigated the effect of obstacle number and shape on PEMFC performance, but also studied the effect of the blockage degree in the channel of PEMFC on its performance. It was found that compared with traditional scheme, longitudinally distributed obstacles scheme can significantly promote reactants transfer to catalyst layer, and the blockage degree in the channel effect PEMFC performance most. The scheme with 10 rectangular obstacles in single channel and 60% channel blockage had the best output performance and the most uniform distribution of reactants and products. Obstacle height distribution can significantly affect PEMFC performance, the blockage degree in the whole basin was large, particularly as the channel was blocked to higher degree in region 2 and region 3, higher net power density and better mass transfer effect can be obtained. Among them, the fuel cell with the blockage degree of 40%, 60% and 60% in region 1, region 2 and region 3 have the best PEMFC output performance and mass transfer, the net power density was 29.8% higher than that of traditional scheme.

• Korean Journal of Ecology and Environment
• /
• v.49 no.3
• /
• pp.236-243
• /
• 2016

It was a case study to use as a basic data for efficient the preservation and management of subalpine coniferous forest in national parks. It is based on inhabitation condition of 210 individuals of Abies koreana Wilson that was found through local investigation in the sub-alpine zone of Jirisan National Park and Songnisan National Park. It analyzed the effect of the geographical location and topographical features, which are the basics of location environment, on the growth of A. koreana. The variables related to the growth of A. koreana are tree height and diameter at breast height. Topographical features include geographical longitude, altitude above sea level, slope of the mountains, aspect that describes the direction in which a slope faces and topographical wetness index. Topographical features were extracted through GIS spatial analysis. It used canonical correlation analysis to estimate whether the two variables groups have related to each other and how much they are related, if any, and estimated the effect of the geographical and topographical features on the growth structure of A. koreana using multiple regression analysis. The tree height and diameter at breast height that represent the growth structure of A. koreana show greater relation to geographical latitude distribution than topographical feature and the geographical and topographical factors show greater relation to diameter at breast height than tree height. The growth structure's variable and geographical and topographical variable of A. koreana have meaningful relation and the result shows that geographical and topographical variables explain 18.1% of the growth structure. The variables that affect the diameter at breast height of A. koreana are geographical latitude, topographical wetness index, aspect and altitude, which are put in order of statistical significance. The higher the latitude is, the smaller the diameter at breast height. Depending on the topographical feature, it becomes bigger. The variable that affects the tree height is topographical wetness index, which was the only meaningful variable. Overall, the tree height and diameter at breast height that are related to the growth structure of A. koreana are affected by geographical and topographical feature. It showed that the geographical feature affected it the most. Especially the effect of water among the topographical features is expected to be bigger than the other topographical factors. Based on the result, it is expected that geographical and topographical feature is an important factor for the growth structure of A. koreana. Even though it considered only the geographical and topographical features and used spatial analysis data produced by GIS, the research results will be useful for investigating and researching the growth environment of coniferous forest inhabiting in sub-alpine zone of national parks and are expected to be used as basic data for establishing measures to efficiently manage and preserve evergreen needleaf tree such as A. koreana.

• Journal of Mechanical Science and Technology
• /
• v.17 no.6
• /
• pp.925-934
• /
• 2003

An experimental study is performed to investigate the characteristics of near wake flow behind a circular cylinder with serrated fins using a constant temperature anemometer and flow visualization. Various vortex shedding modes are observed. Fin height and pitch are closely related to the vortex shedding frequency after a certain transient Reynolds number. The through velocity across the fins decreases with increasing fin height and decreasing fin pitch. Vortex shedding is affected strongly by the velocity distribution just on top of the finned tube. The weaker gradient of velocity distribution is shown as increasing the freestream velocity and the fin height, while decreasing the fin pitch. The weaker velocity gradient delays the entrainment flow and weakens its strength. As a result of this phenomenon, vortex shedding is decreased. The effective diameter is defined as a virtual circular cylinder diameter taking into account the volume of fins, while the hydraulic diameter is proposed to cover the effect of friction by the fin surfaces. The Strouhal number based upon the effective diameters seems to correlate well with that of a circular cylinder without fins. After a certain transient Reynolds number, the trend of the Strouhal number can be estimated by checking the ratio of effective diameter to inner diameter. The normalized velocity and turbulent intensity distributions with the hydraulic diameter exhibit the best correlation with the circular cylinder's data.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.9
• /
• pp.1175-1184
• /
• 2000

Effects of porous wind fences on the wind erosion of particles from a triangular sand pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Flow visualization was carried out to investigate the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the particle size, fence porosity $\varepsilon$ and the height of sand pile. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity $\varepsilon$=30% was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles. With increasing the sand particle diamter, the threshold velocity was also increased. When the height of sand pile is lower than the fence height, threshold velocity is enhanced.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.2 no.1
• /
• pp.65-72
• /
• 2009

For the evaluation of far-field performance by using the near-field probing on the base station dipole array antenna, the effects of mutual coupling depending on the heights between the array antenna with reflector and the probe were analyzed. When the height is varied in the near-field region, S parameters on the input ports of antenna and probe are measured and analyzed to decide the height for the minimum mutual coupling effect and the maximum probing efficiency. This height will be applicable to the near-field probing system design to achieve the precision far-field performance of a base station array antenna system.