• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.52 no.1
• /
• pp.17-28
• /
• 2007

To understand the spring freezing injury symptoms during sensitive growth stage and yield loss of barley and wheat, field tests were done by using vinyl mulching and natural cold weather. The growth stage sensitive were booting, spikelet differentiation and flower organ development stages for both crops. However, barley and wheat differed in their growth responses, in that barley was less affected than wheat. For instance, barley recorded 28 percent dead ears, 10 percent dead plants and 18 percent ear degenerations while wheat recorded higher values of 59 percent, 44 percent and 44 percent, respectively. Although there were no recorded froze-resistant varieties in both barley and wheat, some showed tolerance as their yields were not affected by freezing stress. The 'Chalbori' cultivars of barley and 'Geurumil' and 'Chokwang' cultivars of wheat recorded steady yields. The yield components of barley and wheat that were greatly affected by freezing stress were the number of spike per square and the number of grain per spike. The major cause of yield loss in Suwon 259 and Kangbori was the number of spike per square but not the number of grain per spike. The study showed, however, that both the number of spike per square and the number of grain per spike were vulnerable to freezing and that which contribute much to yield loss of barley and wheat.

• Journal of the Korean Chemical Society
• /
• v.61 no.3
• /
• pp.112-121
• /
• 2017

The purpose of the study was to investigate the effect of explanation in conjunction with gravity and density on students' alternative conceptions for floating and sinking phenomena. The subjects were 140 students of 11th grade in 4 classes of a high school located in Gangwon Province. We divided them in two groups; comparison and experiment. The students of experiment group learned explanation in confection with gravity and density. The students of comparison group learned explanation of pressure as represented in physics textbook. ANCOVAs (analysis of covariance) were conducted using the pretest as a covariance. In items related to characters of matter, 2 items are not significant and only 1 item has significant small effect size (Hedges' g=0.327). In the change of alternative conceptions, there is no meaningful gap between two group. However, in items related to relative weights between object and water, the all items have significant effect sizes (0.286~0.502). In addition, frequency of experiment group's alternative conceptions related to pressure decreases considerably, but comparison group does not. Therefore, the explanation in conjunction with gravity and density suggested in this study can decrease students' alternative conceptions related to floating and sinking phenomena and increase scientific conceptions.

• Progress in Medical Physics
• /
• v.15 no.1
• /
• pp.23-29
• /
• 2004

The relationship between the dose calculated with a radiotherapy treatment planning system (RTPS) and CT number verses the relative electron density curve was investigated for various CT voltages and beam qualifies. We obtained the relationship between the CT numbers and electron densities of the tissue equivalent materials for various CT voltages and beam qualifies. At lower CT voltages, the higher density materials, like cortical bone, showed larger CT numbers and the soft tissues showed no variations. We peformed a phantom study in a RTPS, where a phantom consisted of lung and bone legions in water. We calculated the dose received behind the lung and bone regions for 6 MV photon beams, in which the regions below the lung, water and bone received higher doses in this listed order. The result was the same for 10 MV photon beams. For the clinical application, the doses were calculated for the lung and pelvis. No difference was observed when using different electron density conversion tables with various CT voltages from a same CT. A relative dose difference of 1.5% was obtained when the CT machine for the density conversion table was different from that for the CT image for planning.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.2
• /
• pp.198-203
• /
• 2012

Leguminous cover crops fix nitrogen from the atmosphere. The objective of this research was carried out to decrease fertilizer amount by cover crops-wheat mixtures cultivation. Field experiment was conducted at upland soil 2008 to 2009. Cover crops were used crimson clover and hairy vetch. Treatments consisted of three wheat-crimson clover (wheat 10 kg + crimson clover 1, 3, $5kg\;10a^{-1}$), wheat-hairy vetch mixture (wheat 10 kg + hairy vetch $2kg\;10a^{-1}$), and wheat - hairy vetch mixture - crimson clover (wheat 10 kg + hairy vetch 2 kg + crimson clover $3kg\;10a^{-1}$). These treatments were divided into no fertilizer and top dressing. The yield of wheat and crimson clover mixtures had no significantly differences compared to wheat only at top dressing plots. Also soil chemical and physical properties were a little bit improved such as OM, $NO_3$-N, and bulk density etc by wheat-crimson clover mixtures. Therefore, we suggested that crimson clover and wheat mixture could be used to reduction of fertilizers amount for environmental friendly wheat production.

• Journal of the Korean Magnetics Society
• /
• v.19 no.2
• /
• pp.67-73
• /
• 2009

The changes of geomagnetic flux density distribution on the ground surface by underground empty spaces had been investigated through the variations of the soil density and measuring heights. The geomagnetic flux density distributions were monitored for the surfaces of different density, sink-hole and tunnel by fluxgate-type magnetometer. The underground empty space and low soil density decreased the geomagnetic flux densities, which were decreased from the boundary of raw and low-density (empty) grounds, and showed the lowest value at the center of low-density (empty) ground. The decreases of geomagnetic flux density by underground empty spaces could be found at the surface with the tunnel located at 80 m underground. And, the underground defects of empty spaces, low density zone, fracture zone and sink holes could be monitored by the phenomena of this decreasing flux density.

• Membrane Journal
• /
• v.12 no.3
• /
• pp.171-181
• /
• 2002

The parameter which determines the plateau length of current-voltage curve for ion- exchange membranes was studied at various concentrations of NaCl and different flow rates. Moreover, the feasibility of the electrodialytic removal of 0.1 M NaCl solution at various current densities was tested by assessing the electrodialysis performance parameters such as salt removal efficiency, current efficiency, energy consumption and water dissociation. The diffusion boundary layer (DBL) thickness decreased with the NaCl concentration and flow rate of fled solution and it was observed that the plateau length of current-voltage curves was related with the DBL thickness. The removal efficiency and current efficiency were not affected significantly by the current densities even at the overlimiting current region indicating that most current were passed by electrolyte, and water dissociations are not responsible for the overlimiting current. Energy consumption increased when the current density supplied exceeded the limiting current density (LCD) values, because additional energy was necessary to overcome the plateau potential. Beyond the LCD values the energy consumption required to get a certain removal efficiency was not affected by the current density applied. The result suggests that it is allowed to operate electrodialysis processes at as high as possible current density unless water-splitting does not occur.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.24 no.3
• /
• pp.43-50
• /
• 1979

The effect of planting time and density of soybean on the yield component and yield when intercropped within barley rows or seeded after harvest was evaluated. Early maturing barley variety 'Olbori' was seeded at 2 levels of planting density 40 ${\times}$ 18 and 60 ${\times}$ 18 (row-hill space in em), and the soybean, variety "Dongbuktae", was seeded on June 1 as a inter-crop, June 15 and 30 as a afterharvest crop, all 2 levels of row space (40, 60 cm) and 3 levels of hill space (10, 15, 20 em). Soybean yield was increased in the following conditions: early seeding of soybeans within rows at 60 ${\times}$ 20 em density and soybean seeding after barley harvest at 40 ${\times}$ 20 em density./TEX> 20 em density.

• Journal of radiological science and technology
• /
• v.34 no.3
• /
• pp.195-201
• /
• 2011

We studied the relationship between prediction parameters and bone mineral density for pre-and-post menopausal women. We measured BMI%Fat by BIA, blood pressure and lipid profiles for 483 adult women who are in NPO state. SBP, TC, TG, LDL have significant statistical value in the postmenopause women group and postmenopause woman. The value of postmenopause women of these parameters are lower than premenopause woman. BMD has the most strongest relationship with LBM. The BMD and LDL level of postmenopause women have statistically negative relationship. The results show that for the premenopause cases, weight, BF, and HDL level were the major factors which affect the BMD. For postmenopause cases, however, weight, age, and LDL level turned out to be the most significant factors.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.3
• /
• pp.199-203
• /
• 2019

The penetration depth of a hypervelocity jet exceeding 4 km/s is described by the density ratio of the jet and the target. In the case of the same density, the difference in strength between the targets does not affect the penetration depth difference. This study focuses on the "strength irrelevance" of such a hypervelocity jet. For this purpose, the change of crater pressure caused by shaped charge jet(SCJ) was calculated by finite element analysis and the possibility of polymorphic phase transition of steel material was investigated. Hypervelocity jets were found to cause polymorphic phase transitions in the steel target craters, and the decrease in the fracture toughness of the target is predicted as the cause of the strength irrelevance.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.34 no.3
• /
• pp.225-228
• /
• 1989

Under the different conditions of planting density, maturation dates, stem length, oil contents, stem yield and seed yield of flax were investigated in 1984. The results were as followed: Wiera and Storment Goss were earlier in the maturation dates with increasing plant density, However Taijungsung #1 was delayed. Though there is a difference between the varieties stem length was getting longer with increasing plant density., Oil contents were getting higher with increasing plant density, stem yield and seed yield were increased with increasing plant density, on the contrary those were decreased by the growth of ciliary flax in the case of 1200 plants per 1.2m$^2$. Therefore optimum planting density of flax culture was 12cm x 6cm.