• Journal of the Korea Concrete Institute
• /
• v.26 no.5
• /
• pp.627-634
• /
• 2014

In this study, standoff detonation tests and static beam tests on $160{\times}290{\times}2200mm$ RC beams were conducted to investigate the effect of local damage on the flexural strength and ductility index. And also, blast resistance of RC beams strengthened with steel fiber and FRP sheet were evaluated by these tests. The standoff detonation tests were performed with charge weight of 1kg and standoff distance of 0.1m. After the tests, crater diameters and loss weights of specimens were measured to evaluate the local damage of specimens. Flexural strength and ductility index were measured by conducting the static beam tests on the damaged and undamaged specimens. As a test results, normal concrete specimen(NC) showed relatively large crater and spall diameters that caused weight loss of 23.5kg as a local damage. Whereas, steel fiber reinforced concrete specimen(SFRC) and FRP sheet retrofitted specimens(NC-F, NC-FS) showed higher blast resistance than NC by reducing crater size and weight loss. Flexural strength and ductility index were decreased in case of local damaged specimens by detonation. Especially, large decrease of flexural strength was shown in NC as compared with intact specimen and brittle failure was occurred due to buckling of compressive reinforcement. In case of specimens strengthened with steel fiber and FRP sheet, residual flexural strength and ductility index were increased as compared with NC. In these results, it is concluded that critical local damage can be occurred unless enough standoff distance can be assured even if the charge weight is small. and it is verified that strengthening method using steel fiber and FRP sheet can increase blast resistance.

• Korean Journal of Environmental Agriculture
• /
• v.27 no.4
• /
• pp.328-336
• /
• 2008

Metal mining district drainage is a well recognized source of environmental contamination. Oxidation of metal sulfides produces acidic and metal-rich waters that contaminate local surface water and ground water in mines, mine dumps, and tailing impoundments. This monitoring study was carried out to investigate the stream water quality and pollution as affected by the Sambo mine drainage in relation to the relative distance from the mine. It obvious that pH values of the mine drainage ranged from 5.8 to 6.9, while the average concentrations of the dissolved chemical constituents for EC, $SO_4^{2-}$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were $1.77\;dS\;m^{-1}$, 929, 14.6, 263.3, and 46.9 mg/L in mine drainage discharged from the main waste rock dumps (WRD), respectively. Furthermore, EC values and sulfate concentrations exceeded the critical toxicity levels in agricultural water for rice plant ($1.0\;dS\;m^{-1}$ for EC and 54.0 mg/L for $SO_4^{2-}$). Also, the average of dissolved cadmium concentrations ($0.016{\sim}0.021\;mg/L$) was higher than water quality standard (0.01 mg/L) for agricultural water in Korea, in addition to Zn, Fe and Mn were higher than trace metals maximum concentrations which recommended by FAO for irrigation water. The results indicate that mine drainage discharged from the Sambo mine affected stream water at least to distance of 1 km downstream of the mine water discharge point. EC values, $SO_4^{2-}$ and $Ca^{2+}$ concentrations in discharged water positively correlated with dissolved Cd, Zn, Al and Mn concentrations, while the pH values negatively correlated. In addition, EC values, $SO_4^{2-}$ and $Ca^{2+}$ concentrations were negatively correlated with pH values.

• Journal of Popular Narrative
• /
• v.26 no.1
• /
• pp.135-174
• /
• 2020

The article focuses on the student activism experience of the 1990s and 2010s and on the accumulation of everyday experiences created by the conditions of the 2010s against the backdrop of differences in how the composition of 'we' is portrayed in oral narrative. What stands out in the 90s oral narratives on student activism experiences, which were compiled in the 2010s, is the distancing of the culture of student activism at that time. In the words of speakers who experienced university life in the 1990s, the culture of student activism at the university was created through private relationships, and was, needless to say, considered 'natural'. At the same time, however, the 'natural' is said to be 'abnormal' or 'strange' in the context of the 2010s in which it is being talked about, and is meant to be an experience with a certain distance from the present speakers. This aspect is associated with the conditions under which the experience of the 90s is being described in the 2010s. The present, which explains past experiences to speakers, was explained after the 2016 candlelight protest and Gangnam Station femicide protest, and is described as a world that is qualitatively different from before, and is located as an opportunity to create a critical distance from past experiences. This qualitative change, which raises suspicions about the homogenous "we", is based on a newly acquired sense of gender sensitivity, living since the mid-2010s, when gentler issues were the biggest topic in Korean society, among others. In the 2010s, the composition of 'we' is no longer understood as a community of people who share any commonality, but as individuals who unite despite numerous differences. This reveals the experiences of those who have already embodied this in their everyday senses in the 2010s. The 'we' they formed should have nothing to do with private relationships, nor was homogeneity considered the most prominent group, so it was nothing that could explain the 'me' at the time of the demonstration and outside of the venue. It was in that context that the relevant experience was described in a cautious manner throughout. This, in turn, raises the need to ask and understand a new sense of student activism and, moreover, social movements and the sense of unity as 'we'. It should also be asked who is the main body of the movement and what is the use of asking it. Soon, the need and meaning of defining the fixed identity of 'we' in the movement should be questioned. Therefore, it should be asked what fixed positions or coordinates can really represent someone's position.

• Journal of radiological science and technology
• /
• v.37 no.2
• /
• pp.93-100
• /
• 2014

Recently the development of portable digital wireless imaging system, which acquires digital radiation images by using wireless LAN telecommunications function in an easy and fast way, provides lots of convenience for people. Considering the characteristics of portable imaging tests on emergency and critical patients, this study aims to suggest guidelines for Digital wireless detector by evaluating the effect of de-centering of focus-grid and displacement of subject in detector on the quality of image. The equipments used for this study were Elmo-T6 Digital Mobile X-ray system (SIMAZU Corp.), el' Tor ($14{\times}17$ "Wireless detector), Grid (10:1) and Chest & head phantom. After acquiring post-processing image according to dose increase and de-centering image of grid-focus and head phantom displacement image, this study compared, analyzed and evaluated these images by using a digital image analysis program by Image J. In the change of images based on dose increase, images were rough in the dose of 0.5 mAs, while there was no difference among images in the proper dose of 1~2 mAs and, especially from 2.5 mAs, average value of pixels radically decreased, affecting contrast. Over 3 mAs, contrast dropped due to saturation phenomenon of lungs. As the result of analysis using Image J program, with the increase of displacement between focus-grid and head phantom, the frequency of low pixel value also increase, causing the outline of surface image to disappear, which in turn affects contrast. For better quality imaging, a radiographer must be aware before the time of test that the image quality can be changed based on the critical patient's posture, movement, respiration, displacement of X-ray tube and distance of imaging.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.33 no.4
• /
• pp.352-359
• /
• 1997

The visual acuity of filefish Stephanolepis cirrhifer was studied through a series of experiments by observing their responses to target plates. The fish were trained to respond to the target plates made of white acrylic resin with a vertical black line 5cm long in the center. The width of the black line ranged from 0.2mm to 8.0 mm. The line width was diminished unto the fish could no longer distinguish the line at a distance of 100 cm from the target plate. This was repeated under light intensities of 400, 20, 5, 3 and 1 lx at the water surface. Fish were rewarded with bait in front of the target plate if the fish went to the target date (i.e., success).The results show that the training effect of 1lensh had a success rate of over 80% and that the reach times to the target plates were 4~5 seconds over 210 experimental tunes. The success rate was high using the thick line with strong apparent contrast, but was low at the 1 lx. The visible critical width of line became thick with decreasing light intensity, 0.24mm at 400 lx, followed by 0.30mm at 20 lx, 0.40mm at 5 lx, 0.46 mm at 3 lx and 2.87mm at 1 lx. The apparent contrast for visible critical width of line increased with decreasing light intensity, 0.01 at 400 and 20 lx, 0.02 at 5 lx, 0.03 at 3 lx and 0.09 at 1 lx. The line acuity of filefish was best 1.21 at the 400 lx, followed by 0.97 at 20 lx, 0.73 at 5 lx, 0.63 at 3 lx and sharply decreased to 0.10 at 1 lx. The visible ranges for 1mm and 6mm in width of line were about 4.2 m and 25.0 m at the 400 lx light intensity and decreased m 1/14 times and 1/12 times of the 400 lx at 1 lx, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.35 no.4
• /
• pp.352-361
• /
• 1990

The reducing effect of wind injury was investigated using several wind-break nets in Youngdeok province where cold-wind damage is often occurred during rice growing season. The white-head damage of rice have been often occurred by typhoon during the period between August 15 to September 10 in the cold wind area of the eastern coastal during the last 11 years (1979-1989). This may suggest that the critical period for heading will be by August 15 in the regions. High evaporation coefficient, more than 250 due to typhoon passage over the regions resulted high injury of white head. Generally, the wind injury have been caused by warm and dry westerlies through Fohn apperance in Taebaeg mountains and by cool-humid wind which blows from coast to inland. The frequency of occurrence of the two types of typhoons were 25, 20%, respectively during rice cultivation. The instalation of wind-break net significantly reduced the wind blowing speed, depending on the net mesher with the higher effect in dence net. The distances between the net and cropping area also affect the wind speed: 23% reduction at 1m distance. 34% at 10m and 28% at 20m, respectively. The reducing effect was also observed even at 10 times height of the wind-break net. The instalation of wind-break net gave several effects on climate factor, showing that temperature increased by 0.8$^{\circ}C$(maximum), 0.7$^{\circ}C$(minimum), 0.6$^{\circ}C$(average) : water temperatures increased by 0.5$^{\circ}C$(maximum), 0.6$^{\circ}C$(minimum), 0.5$^{\circ}C$(average) : soil temperature increased 0.4$^{\circ}C$. The earlier heading and increasing growth rate, use of light, culm length, panicle number per hill, spikelet number per panicle, fertility and 1,000 grain weight were observed in the fields with the wind-break nets resulting in 10-15% increase in rice yield using 0.5${\times}$0.5cm nets. The increasing seedlings per hill gave higher grain yield by 13% in the cold wind damage regions of eastern coastals. and the wind-break was more significant in the field without the wind-break net. Wind injury of rice plant in the cold wind regions of eastern coastals in korea could be reduced by selection of tolerant varieties to wind injury, adjustment of transplanting time, and establishment of wind-break nets.

• Korean Journal of Cognitive Science
• /
• v.11 no.2
• /
• pp.37-51
• /
• 2000

The present study compared computer users target-selection response patterns when the targets were varied in terms of their relative location and distance from the current position of the cursor. In Experiment 1, where the mouse was used as an input device, the effects of different directions and distances of simple target(small rectangle) on target-selection response were investigated. The results of Experiment 1 can be summarized as follows: (1) Overshooting was more frequent than either undershooting or correct movement and (2) this tendency was more prominent when the targets were presented in the oblique direction or in farther location from the current cursor position. (3) Although the overshooting and undershooting were more frequent in the oblique direction, the degree of deviation was larger in horizontal and vertical direction. (4) Time spent in moving the mouse rather than that spent in planning, calibrating or clicking was found to be the most critical factor in determining total response time. In Experiment 2, effects of the font size and line-height of the target on target-selection response were compared with regard to two types of input devices(keyboard vs. mouse). The results are as follows: (1) Mouse generally yielded shorter target-selection time than keyboard. but this tendency was reversed when the targets were presented in horizontal and vertical directions. (2) In general, target-selection time was the longest in the condition of font size of 10 and line-height of 100%, and the shortest in the condition of font size of 12 and line-height of 150%. (3) When keyboard was used as the input device, target-selection time was shortest in the 150% line-height condition, whereas in the mouse condition, target-selection time tended to be increased as the line-height increased. which resulted in the significant interaction effect between input device and line-height. Finally, several issues relating to human-computer interaction were discussed based on the results of the present study.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.3
• /
• pp.252-261
• /
• 2003

Although the young spike of barley (Hordeum vulgare L.) or wheat (Triticum aestivum L.) is known as the most susceptible part to spring cold injury, the risk of cold injury is apt to be ignored in most breeding program due to the importance of early maturity. Based on these aspects, the types and inducing time, temperature conditions for induction and effects of cold injury on growth and yield in this study were investigated under greenhouse and field conditions through three years (1997-1999). In natural condition, low temperature around -2.4∼$-10.2^{\circ}C$ caused the death of plant. Several cold injury types such as partial degeneration of spike, partial discoloration of leaf, spike and awn, discoloration of culm and white spike were observed at low temperature around $-3.1^{\circ}C$. Low temperature around -2.4∼$-8.6^{\circ}C$ and 1.3-$7.6^{\circ}C$ caused degeneration and sterility of spike, respectively. Most materials were prepared to the spikelet foundation stage, spikelet differentiation stage, development stage of flower organ, booting stage and heading stage, which were known having risk for cold injury in field condition. Although most of the controlled stages were sensitive to the induced low temperature, booting stage was the most sensitive stage for cold injury. All of growth stages which were treated-heading stage, booting stage, development stage of flower organ, spikelet differentiation stage, spikelet foundation stage-were responded to low temperature treatment but the symptoms revealed were very specific according to the growth stages. Ears of plant in heading stage were discolored to white. Ears of plant in booting stage were degenerated in all or part of one. Plants in spikelet differentiation stage were sterile in all or part of one. When tried to detect the specific differences between normal and cold injured plants in appearance, spike length, distance between spike and flag leaf and the first internode length could be the critical points for occurrence of spike death caused by cold injury. In barley, the elongation of spike was stopped on 3.2cm after occurrence of spike degeneration, 4.7cm after occurrence of partial degeneration of spike, 5.0cm after occurrence of white spike. In wheat, it was stopped on 1.6cm after occurrence of stem death, 3.3cm after occurrence of spike degeneration, 8.3cm after occurrence of partial degeneration of spike, 8.1cm after occurrence of white spike, 7.5cm after partial discoloration of leaf and 9.3cm after partial discoloration of spike. The obtained results from low temperature treatment induced in growth chamber were similar to the field experiment, Beacuse the death of spikes was more when low temperature was treated two times than one times, the temperature should be upgrade to -3$^{\circ}C$ in order to get the same condition with field test.

• Journal of the Korean association of regional geographers
• /
• v.14 no.3
• /
• pp.269-278
• /
• 2008

This research analyzed the effect of lessons with the GIS application as an alternative scheme of teaching and learning of geography in elementary school. Two classes in the third grade at Y elementary school in Andong were selected to conduct lessons on 'The Landscape of My Hometown' from March 6 through June 30, 2006. In the experimental class, the lessons were conducted with the GIS application; while, in a comparative class, the lessons were carried with usual teaching and learning method. To find out the effect of lessons with the GIS application, differences of spatial cognition of students were figured out between groups, and before and after lessons. The difference between the spatial concept development stages and materials on the textbook discouraged students to pursue their learning as well as made them hard to achieve the goals of lessons. The GIS application had been suggested as an alternative teaching and learning method to overcome the difference; however, it has been hard to find any empirical research to verify the effect of the lessons with GIS application in elementary school. The ability of spatial cognition of the third graders at an elementary school was very low as the result of that curricula in the first and second grades dealt with sketch maps as teaching and learning media. The map learning of third grader on the transitional stage would play the critical role to develop the spatial cognition ability in the future. The field study contributing to developing spatial cognition ability would not be conducted at school. It was required to have the alternative learning schemes such as lessons with GIS application. The lessons with GIS application verified effect of GIS application as the alternative method. The GIS application helped students to recognize landmarks, directions and distance effectively as well as reduced the spatial cognition difference among individuals and/or groups.

• Radiation Oncology Journal
• /
• v.17 no.1
• /
• pp.43-51
• /
• 1999

Purpose : To discuss the technical aspect of interstitial brachytherapy including method of implant, insertion time of radioactive source, total radiation dose, and complication, we reviewed patients who had diagnoses of soft tissue sarcoma and were treated by conservative surgery, interstitial implant and external beam radiation therapy Materials and Methods : Between May 1995 and Dec. 1997, ten patients with primary or recurrent soft tissue sarcoma underwent surgical resection (wide margin excision) and received radiotherapy including interstitial brachytherapy. Catheters were placed with regular intervals of 1 ~l.5 cm immediately after tumor removal and covering the critical structures, such as neurovascular bundle or bone, with gelform, muscle, or tissue expander in the cases where the tumors were close to those structures. Brachytherapy consisted of high dose rate, iridium-192 implant which delivered 12~15 Gy to 1 cm distance from the center of source axis with 2~2.5 Gy/fraction, twice a day, starting on 6th day after the surgery, Within one month after the surgery, total dose of 50~55 Gy was delivered to the tumor bed with wide margin by the external beam radiotherapy. Results : All patients completed planned interstitial brachytherapy without acute side effects directly related with catheter implantation such as infection or bleeding. With median follow up duration of 25 months (range 12~41 months), no local recurrences were observed. And there was no severe form of chronic complication (RTOGIEORTC grade 3 or 4). Conclusion : The high dose rate interstitial brachytherapy is easy and safe way to minimize the radiation dose delivered to the adjacent normal tissue and to decrease radiation induced chronic morbidity such as fibrosis by reducing the total dose of external radiotherapy in the management of soft tissue sarcoma with conservative surgery.