• Journal of the Korean Society of Radiology
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• v.11 no.4
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• pp.177-181
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• 2017

Dose response curves using absorbed dose to the biological effect are usually available in case of conventional X beam. However, absorbed dose is not consider in treatment planning for carbon beam such as heavy ions. Because the biological effects also depend on other quantities such as the local variation, which is often characterized by the linear energy transfer (LET). So LQ model cannot explain the entire response of fractionated carbon beam irradiation. The variation in LET with penetration depth leads to substantial differences in biological effect of carbon beam. And it is therefore essential in treatment planning to calculate not only the absorbed dose but also the LET to estimate the biological outcome of the radiation of interest. LET variation plays an important role in the fractionated irradiations. It is suggested that consideration of LET is necessary in biophysical model.

• Korean Journal of Weed Science
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• v.9 no.3
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• pp.238-244
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• 1989

The experiment was carried out to evaluate the herbicidal properties of dithiopyr(3, 5-pyridine dicarbothioic acid-2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-S,S-dimethyl ester). Weeding effect of dithiopyr was determined under various factors such as dosage, soil type, leaching amount, temperature, water depth, overflow time, and application time and method. Dithiopyr showed very high phytotoxic activity on most major annuals weeds, expecially Echinochloa crus-galli and Monochoria vaginalis. Excellent control of Echinochloa crus-galli was obtained at 0.04kg a.i./ha with preemergence application and 0.12kg a.i./ha with early post-emergence application (12 DAT ; Echinochloa crus-galli of 1.5 leaf stage). Weeding effect of dithiopyr decreased when applied at the soil surface 2days before transplanting. Soil type, leaching amount, temperature, water depth, overflow time did not affect the weeding effect.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1148-1155
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• 2010

To suggest a modified shallow foundation design method which can be considered the scale effect of foundation on IGM(intermediate geomaterial) soil layer, the weathered soil layer that is uniformly formed up to 8m(2B) with over 50 N-value is selected and 3 times field loading tests are performed on several sized square-shaped shallow foundations with 30, 75, 150, 240 and 400cm in width respectively. Because the soil modulus of elasticity(Es) calculated by soil investigation and 1st field test(PBT) results showed an underestimated tendency, a modified correlation is required for the reasonable estimation of Es on the weathered soil. Also, the N-value was increased with an increasing in depth. However, the N-values around the test foundations showed the different values even though the foundations on the same level because the test site was arranged by excavation. Therefore, the more detail soil investigations are required for the each test foundations respectively. Since Es based on elasticity theory is determined by the stress distribution shape of the foundation and elasticity modulus of the soil, the scale effect considered pressure-settlement curve can be clearly derived from the correlation on stress distribution shape and the variation of soil elasticity modulus with depth. Therefore, the modified correlation will be suggested to estimate a reasonable Es on the weathered soil, and the scale effect considered shallow foundation design method is also developed based on the elastic theory and field tests in this research.

• Ocean and Polar Research
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• v.33 no.1
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• pp.55-68
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• 2011

The distribution and inter-annual variation of nutrients (N, P, Si) and dissolved/particulate organic carbon were investigated in the equatorial thermocline ridge ($7^{\circ}{\sim}11.5^{\circ}N$, $131.5^{\circ}W$) of the northeast Pacific. From the Oceanic Nino Index and Multivariate ENSO Index provided by NOAA, normal condition was observed in July 2003 and August 2005 on the aspect of global climate/ocean change. However, La Ni$\~{n}$a and El Ni$\~{n}$o episodes occurred in July 2007 and August 2009, respectively. Thermocline ridge in the study area was located at $9^{\circ}N$ in July 2003, $8^{\circ}N$ in August 2005, $10^{\circ}N$ in July 2007, and $10.5^{\circ}N$ in August 2009 under the influence of global climate/ocean change and surface current system (North Equatorial Counter Current and North Equatorial Current) of the northeast Pacific. Maximum depth integrated values (DIV) of nutrients in the upper layer (0~100 m depth range) were shown in July 2007 (mean 21.12 gN/$m^2$, 4.27 gP/$m^2$, 33.72 gSi/$m^2$) and higher variability of DIV in the equatorial thermocline ridge was observed at $10^{\circ}N$ during the study periods. Also, maximum concentration of dissolved organic carbon (DOC) in the upper 50 m depth layer was observed in July 2007 (mean $107.48{\pm}14.58\;{\mu}M$), and particulate organic carbon (POC, mean $9.42{\pm}3.02\;{\mu}M$) was similar to that of DOC. Nutrient concentration in the surface layer increased with effect of upwelling phenomenon in the equatorial thermocline ridge and La Ni$\~{n}$a episode, which had formed in the central Pacific. This process also resulted in the increasing of organic carbon concentration (DOC and POC) in the surface layer. From these results, it is suggested that spatial and temporal variation of chemical and biological factors were generated by physical processes in the equatorial thermocline ridge.

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.33-40
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• 2015

PURPOSES: Evaluation of the wind speed effect on the temperature drop of an asphalt mixture during construction, by using the transient heat transfer theory and dominant convective heat transfer coefficient model. METHODS: Finite difference method (FDM) is used to solve the transient heat transfer difference equation numerically for various wind speeds and initial temperature conditions. The Blasius convective heat transfer coefficient model is adapted to account for the effect of wind speed in the temperature predictions of the asphalt mixture, and the Beaufort number is used to select a reasonable wind speed for the analysis. As a function of time and depth, the temperature of the pavement structure is predicted and analyzed for the given initial conditions. RESULTS : The effect of wind speed on the temperature drop of asphalt mixture is found to be significant. It seems that wind speed is another parameter to be accounted for in the construction specifications for obtaining a better quality of the asphalt mixture. CONCLUSIONS: It is concluded that wind speed has a significant effect on the temperature drop of the asphalt layer. Although additional field observations have to be made to reflect the effect of wind speed on the construction specifications, it appears that wind speed is a dominant variable to be considered, in addition to the atmospheric temperature.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.64-72
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• 2014

In the past, prism patterns have been linear triangular shapeswith a $90^{\circ}$ angle; however, new micro prism patterns having acute angles or obtuse angles have recently been the subject of demandin the display, lighting and photovoltaic industries. Micro-cutting experiments for micro-prism patterns having $60^{\circ}$, $90^{\circ}$, and $120^{\circ}$ angles on an electroplated Ni mold were performed and it was found in this study that the specific cutting resistance increased with a decrease in the tool angles (prism pattern angles). The cause of this variation had been thought to be the increase of the ploughing force due to tip rounding and the friction force due to the edge effect. However, the depth of the cut was large enough that it was possible to neglect these effects. Therefore, this study introduced the concept of representative stress of indentation. The measured stress was varied according to the indentation depth eventhoughthetestedspecimenswereidentical ; the varied stress was termed the representative stress. According to indentation theory, the strain that the Ni mold experienced increased with a decrease in the tool angle. Based on the stress-strain relationship, higher strain means higher stress and higher specific cutting resistance. Therefore, the specific cutting resistance was higher at smaller tool angles that had higher strain and stress.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.6
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• pp.629-640
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• 2008

This study investigates long-term trends and characteristics of aerosol optical depth ($\tau_a$) and Angstrom exponent (${\AA}$) around Korea in order to understand aerosol effects on the regional climate change. The analysis period is mainly from 1999 to 2006, and the analysis sites are Anmyun and Gosan, the background monitoring sites in Korea, and two other sites of Xianghe in China and Shirahama in Japan. The annual variations of $\tau_a$ at Anmyun and Gosan have slightly systematic increasing and decreasing trends, respectively. $\tau_a$ at Anmyun shows more substantial variation, probably because of it's being closer and vulnerable to anthropogenic influence from China and/or domestic sources than Gosan. Both values at Gosan and Anmyun are approximately 1.5 times greater than those at Shirahama. The monthly variation of $\tau_a$ exhibits the highest values at late Spring and the lowest at late-Summer, which are thought to be associated with the accumulation of fine aerosol formed through the photochemical reaction before the Jangma period and the scavenging effect after the Jangma period, respectively. Meanwhile, the episode-average $\tau_a$ for the Yellow dust period increases 2 times greater than that for the non-Yellow dust period. A significant decrease in ${\AA}$ for the Yellow dust period is attributable to an increase in the loading of especially the coarse particles. Also we found no weekly periodicity of $\tau_a$'s, but distinct weekly cycle of $PM_{10}$ concentrations, such as an increase on weekdays and a decrease on weekends at Anmyun and Gosan. We expect these findings would help to initiate a study on aerosol-cloud interactions through the combination of surface aerosol and satellite remote sensing (MODIS, Calipso and CloudSat) in East Asia.

• Journal of Welding and Joining
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• v.29 no.6
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• pp.71-76
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• 2011

Submerged arc welding method from both sides is generally applied to the welding of main panel manufacturing process during ship construction. The tandem SAW method is applied to improve the productivity. The various weld defects that occur during tandem SAW method are melt through, incomplete penetration, undercut and overlap etc. It could be thought that the reasons for these defects are mainly lack of prediction ability for penetration depth and deposited metal area. In this research, total 5 kinds of welding factors for experiment like current of lead pole, voltage of lead pole, current of trail pole, voltage of trail pole and welding speed are adopted. Weld tests are carried out for the analysis of variation effects of these factors on penetration depth and deposited metal area. Based on the test and analysis results, it is possible to obtain the prediction equation for the effect of these factors on the amount of deposited metal and penetration depth. As per the verification of the results by additional tests, it is confirmed that the prediction equation, include a error margin of ${\pm}2mm$ for penetration depth and ${\pm}10mm2$ for deposited metal area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.232-236
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• 1994

The term underground stem is not used correctly as mesocotyle that is the first internode of barley, wheat and rye. Mesocotyle does not elongate and it remain in the seed in case of these crops. The elongated stem is second internode of these crops and not mesocotyle but rhizome or underground stem. The node on which the underground stem is attached is coleoptile node and coleptile is attached here. The objective of this study was to determine if the depth of sowing affect the coleoptile length and plant height. The deeper sowing caused the longer coleoptile length and plant height. Coleoptile length and plant height of 2cm depth of sowing showed significant difference with 6cm and 10cm depth of sowing in barley and wheat. Variation of these two characters were high in rye and corn because these crops were both heterogeneous due to out crossing. All the varieties of 4 crops showed significant correlation between coleoptile length and plant height. Chilbohomil showed highly significant correlation between two characters.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.95-103
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• 2013

Half Cell Potential (HPC) technique has been widely adopted for its quantitative evaluation of corrosion possibility. In this study, RC specimens with three different cover depths (10mm, 30mm, and 60mm) and w/c ratios (0.35, 0.55, and 0.70) are prepared and accelerated salt spray test (SST) is performed for 45 days. Steel corrosion occurs in the specimens with 0.55 of w/c and 10mm of cover depth. In the case of 0.70 of w/c and 30mm of cover depth, steel corrosion is also monitored. Considering the effect of cover depth and w/c ratio, HCP evaluation equation is proposed and the condition which can control steel corrosion is obtained. Furthermore, anti-corrosive conditions containing w/c ratio and cover depth are analyzed through Life 365 program and the conditions are compared with the results from this study.