• Ultrasonography
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• v.32 no.1
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• pp.59-65
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• 2013

Purpose: The purpose of this study is to establish the methodology regarding synthesis of ultrasound contrast agent imaging, and to evaluate the characteristics of the synthesized ultrasound contrast agents, including size or degradation interval and image quality. Materials and Methods: The ultrasound contrast agent, composed of liposome and SF6, was synthesized from the mixture solution of $21{\mu}mol$ DPPC (1, 2-Dihexadecanoyl-sn-glycero-3-phosphocholine, $C_{40}H_{80}NO_8P$), $9{\mu}mol$ cholesterol, $1.9{\mu}mol$ of DCP (Dihexadecylphosphate, $[CH_3(CH_2)_{15}O]_2P(O)OH$), and chloroform. After evaporation in a warm water bath and drying during a period of 12-24 hours, the contrast agent was synthesized by the sonication process by addition of buffer and SF6 gas. The size of the contrast agent was controlled by use of either extruder or sonication methods. After synthesis of contrast agents, analysis of the size distribution of the bubbles was performed using dynamic light scattering measurement methods. The degradation curve was also evaluated by changes in the number of contrast agents via light microscopy immediate, 12 hours, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours, and 84 hours after synthesis. For evaluation of the role as an US contrast agent, the echogenicity of the synthesized microbubble was compared with commercially available microbubbles (SonoVue, Bracco, Milan, Italy) using a clinical ultrasound machine and phantom. Results: The contrast agents were synthesized successfully using an evaporation-drying-sonication method. The majority of bubbles showed a mean size of 154.2 nanometers, and they showed marked degradation 24 hours after synthesis. ANOVA test revealed a significant difference among SonoVue, synthesized contrast agent, and saline (p < 0.001). Although no significant difference was observed between SonoVue and the synthesized contrast agent, difference in echogenicity was observed between synthesized contrast agent and saline (p < 0.01). Conclusion: We could synthesize ultrasound contrast agents using an evaporation-drying-sonication method. On the basis of these results, many prospective types of research, such as anticancer drug delivery, gene delivery, including siRNA or microRNA, targeted molecular imaging, and targeted therapy can be performed.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.399-407
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• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Cross-Cultural Studies
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• v.48
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• pp.31-66
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• 2017

This study examines ways of recognizing and aspects of describing Korean modern literature revealed by each literary history from the viewpoint of 'transculturation', focusing on Lim Jeon-Hye's "History of Korean Literature in Japan until 1945", Shirakawa Yutaka's "Footsteps of Korean Modern Literature", and Saegusa Toshikatsu's "Taste of Korean Literature" from the history of Korean literature written in Japan. First, Lim Jeon-Hye periodically examines Korean literature written in Japan, focusing on literary activities of Korean students in Japan and the proletarian literature movement, and addresses points of active cultural negotiation, mutual understanding and political solidarity between Korea and Japan. Shirakawa Yutaka focuses on the concurrency and connection of Korea, China, and Japan in the process of modern literary formation, covering Japanese language literature and pro-Japanese literature with great care, and describes the middle-layer position as a mediating researcher in the conflicting boundaries between Korea and Japan. Saegusa Toshikatsu provides interesting transcultural momentum in exploring internal logic and denotation of Korean literature via comparative literature review encompassing East Asia, implementation of literary forms and themes connecting tradition and modernity, and an out-of-boundary point of view to overlook 'pro-Japanese literature', etc. Transcultural aspects in this literary history to examine are as follow. First, the history of Korean modern literature based on 'national literature history' is catabolized in the magnetic field of the 'colonial experience' and 'national nationalism' and considered in multifaceted context. Second, they provide the possibility of three-dimensional and micro-narrative description of literature that complement the narrative aspect of existing Korean literature history. Third, they provide an opportunity to expand and open the description of literature history through acceptance of comparative literary perspectives encompassing East Asia. Fourth, through discovery of Korean-Japanese literature and Japanese language literature, they contribute to broadening the history of Korean modern literature and enriching foundations.

• The Korean Journal of Archival Studies
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• no.59
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• pp.207-275
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• 2019

This archiving project of the survivors of suicide was done with the survivor supporting team of the Seoul Suicide Prevention Center. The survivor supporting team was operating a Self-help Support Group for the emotional support of the survivors of suicide. A Self-help Support Group is a place for the survivors of suicide to regularly meet and share their suffering by talking of topics hard to discuss elsewhere. As the Self-help Support Group progressed members who acted as the leader of the group appeared. They formed an essay group that writes together. Two fathers who lost their sons, two mothers who lost their daughters, a mother who lost her son, a wife who lost his husband. The essay group met each week in a place facing Sajik Park. Through the windows that took up the whole side of the room, evening was coming in. The things that happened during the day went away towards Inwang mountain following the setting sun. Ten people (six members of the essay group, three from the survivor support team, a historian for unique conversation) sat around a table, facing each other. "Now, what shall we do?" History for unique conversation is a time that archives life by sharing conversations. At times a complete stranger, and other times people who share their ordinary lives sit around together (3-9 people, sometimes about 15). On the table there is coffee, bread, fruits and salads, and sometimes a dish someone heartily prepared. When a bottle of wine is placed on the table, each takes a glass. Morning, afternoon, the time the evening is welcomed in, late night. It does not matter which. For six months, 3 hours when meeting every week, 6 hours when at every other week. A room where the ambience is like that of a kitchen where sunlight enters, or a cozy living room is the best location. However, there are many times when it is held in a multipurpose room in the suburbs where many meetings are held, or in a classroom of a school. The meeting place is decided according to different situations of the time. There are no participation requirements as it is said to be for themselves to write down according to archiving form while looking back their lives thoroughly, and they are the only ones to stop themselves. The archives landscape from far away would seem like trying to do some talking. However, when going into a microscopic situation one must leave themselves to the emotional dynamics. It is because it archives the frustration and failures one experienced through life. A participator of history for unique conversation must face the sufferings of their life. The archiving project took place in 2013 to 2014. Many years have passed. Has the objective distance for archiving the situation of that time been secured? That may be uncertain, but I will speak of a few stray thoughts on archiving while depicting the process and method of operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.139-147
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• 2021

Livestock manure is used as an organic fertilizer to replace chemical fertilizers after sufficient fermentation in an aerobic bioreactor. On the other hand, liquid manure disposal problems occur repeatedly because soil spraying is restricted during the summer when the crops are growing. To use liquid fertilizer (LF) as an additional nutrient source for crops, it is necessary to reduce the amount of suspended solids (SS) in the liquid fertilizer and secure stability problems against pathogenic microorganisms. This study examined the effects of the simultaneous SS removal and E.coli sterilization in the LF using the microbubble (MB) generator (FeMgO catalyst insertion). The remaining SS were further removed using the integrated microbubble and microfilter system. During the floating process in the MB device, the SS were removed by 57.9%, and the coliform group was not detected (16,200→0 MPN/100 mL). By optimizing the HRT of the integrated system, the removal efficiency of the SS was improved by 92.9% under the 0.1h of HRT condition. After checking the properties of the treated LF, 64.5%, 70.1%, 54.9%, and 51.5% of the TCOD, SCOD, PO4-P, and TN, respectively, were removed. The treated effluent from such an integrated system has a lower SS content than that of the existing LF and does not contain coliforms; therefore, it can be used directly as an additional fertilizer.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.78-99
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• 2020

The Buddha triad and 16 Arhat statues carved on the rock surface at Seongbulsa temple is the only domestic remaining example of all 16 Arhats, so its academic value is very high. However, it is severely damaged and so required a stability evaluation through study of digital documentation and precise diagnosis for the purpose of comprehensive conservation. This process established that the Buddha statues were of similar scale, while the Arhats showed a wide variety of sizes, and the two kith and kin in the volume were larger than the Arhats. It was estimated that the statues of food for Buddha are similar to the Arhat statues, and most of the statues are well-formed. The rock used to carve the Buddha statues is banded gneiss with distinct foliation, alternating between white bands of quartz and feldspar and black bands composed of biotite. The Buddha statues have been damaged by physical weathering, discoloration, and biological contamination. In damage evaluations, joint (3.6 crack index), peeling (5.2%), exfoliation (1.7%), and falling off (0.1%) were observed on the rock surface of the Buddha statues. In particular, due to severe biological weathering, stage 9 and 10 biological coverage of the rock surface accounted for 57.5% of the total area, and stages 5 to 8 also accounted for a high share at 22.3%. The discoloration factors were shown to be dark brown and white with Fe, Ca, and S, and a large amount of C detected in the blackened contaminants, and the damage weight high in all areas. Discontinuities in different directions were identified in the rock surface. Analysis of potential rock failure types indicated that there is a possibility of plane and toppling failure, but wedge failure is unlikely to occur. The mean ultrasonic velocity of the main rock surface was 2,463m/sec, the lower part of the left side with a large number of joints was relatively low, and the highly weathered (HW) type to the completely weathered (CW) type concentrated distribution, showing weak properties. For the Buddha statues, conservation treatment is required for about 14.9% of micro cracks and 58.9% of exfoliation cracks. In addition, in order to improve the conservation environment of the Buddha statues, maintenance of drainage and ground preparations for the rock surface gradient and plants are necessary, and protection facilities should be reviewed for long-term conservation and management purposes.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.651-662
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• 2022

The electrochemical impedance spectroscopy(EIS) method was used to evaluate the concrete deterioration process related to chloride-induced steel corrosion with various corrosion levels(initiation, rust propagation and acceleration periods). The impressed current technique, with four total current levels of 0C, 13C, 65C and 130C, was used to accelerate steel corrosion in concrete cylinder samples with w/c ratio of 0.4, 0.5, and 0.6, immersed in a 0.5M NaCl solution. A series of EIS measurements was performed to monitor concrete deterioration during the accelerated corrosion test in this study. Some critical parameters of the equivalent circuit were obtained through the EIS analysis. It was observed that the charge transfer resistance(R_c) dropped sharply as the impressed current increased from 0C to 13C, indicating a value of approximately 10kΩcm². However, the sensitivity of R_c significantly decreased when the impressed current was further increased from 13C to 130C after corrosion of steel had been initiated. Meanwhile, the double-layer capacitance value(C_dl) linearly increased from 50×10^-6μF/cm² to 250×10^-6μF/cm² as the impressed current in creased from 0C to 130C. The results in this study showed that monitoring C_dl is an effective measurement parameter for evaluating the progress of internal concrete damages(de-bonding between steel and concrete, micro-cracks, and surface-breaking cracks) induced by steel corrosion. The findings of this study provide a fundamental basis for developing an embedded sensor and signal interpretation method for monitoring concrete deterioration due to steel corrosion at various corrosion levels.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.4
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• pp.409-421
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• 2022

Achieving a highly resolved spatial distribution of Mn-bearing minerals and elements in the natural ferromanganese nodules can provide detailed knowledge of the temporal variations of geochemical conditions affecting the formation processes of nodules. While a recent study utilizing Raman spectroscopy has reported the changes in the manganate mineral phases with growth for spherical nodules from the Arctic Sea, the distributions of minerals and elements in the nodules from the shallow Arctic Sea with non-spherical forms have not yet fully elucidated. Here, we reported the micro-laser Raman spectra with varying data acquisition points along three different profiles from the center to the outermost rim of the non-spherical ferromanganese nodules collected from the East Siberian Sea (~73 m). The elemental distributions in the nodule (such as Mn, Fe, etc.) were also investigated by energy dispersive X-ray spectroscopy (EDS) analysis to observe the internal structure and mineralogical details. Based on the microscopic observation, the internal structures of a non-spherical nodule can be divided into three different regions, which are sediment-rich core, iron-rich substrate, and Mn-Fe layers. The Raman results show that the Mn-bearing mineral phases vary with the data acquisition points in the Mn-Fe layer, suggesting the changes in the geochemical conditions during nodule formation. In addition, we also observe that the mineral composition and structural characteristics depend on the profile direction from the core to the rim. Particularly, the Raman spectra obtained along one profile show the lack of Fe-(oxy)hydroxides and the noticeably high crystallinity of Mn-bearing minerals such as birnessite and todorokite. On the other hand, the spectra obtained along the other two profiles present the presence of significant amount of amorphous or poorly-ordered Fe-bearing minerals and the low crystallinity of Mn-bearing minerals. These results suggest that the diagenetic conditions varied with the different growth directions. We also observed the presence of halite in several layers in the nodule, which can be evidence of the alteration of seawater after nodule formation. The current results can provide the opportunity to obtain detailed knowledge of the formation process and geochemical environments recorded in the natural non-spherical ferromanganese nodule.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.2
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• pp.68-81
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• 2023

This study aims to establish a scenario based on the spacing and arrangement of the roadside trees to reduce heat waves and fine dust in cities that occurred during the urbanization process and to quantitatively analyze the degree of reduction. The ENVI-met 5.0.2v model, a micro-climate simulation program, was used to analyze the degree of improvement in the thermal environment and fine dust according to the roadside tree scenario. As a result of temperature analysis according to street tree spacing, the narrower the distance between roadside trees, the lower the temperature during the day as the number of planted trees increased, and a similar pattern was shown regardless of the distance between roadside trees in the morning and evening. In the case of fine dust emitted from the road, the concentration of fine dust increased slightly due to the increase in roadside trees, but the concentration of sidewalks where people walk increased slightly or there was no difference because of blocking fine dust on trees. The temperature according to the arrangement of street trees tended to decrease as the number of planted trees increased as the arrangement increased. However, not only the amount of trees but also the crown projected area was judged to have a significant impact on the temperature reduction because the temperature reduction was greater in the scenario of planting the same amount of trees and widening the interval of arrangement. In terms of the arrangement, the fine dust concentration showed a difference from the results according to the interval, suggesting that the fine dust concentration may change depending on the relationship between the main wind direction and the tree planting direction. By quantitatively analyzing the degree of thermal environment and fine dust improvement caused by roadside trees, this study is expected to promote policies and projects to improve the roadside environment efficiently, such as a basic plan for roadside trees and a project for wind corridor forests.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.4
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• pp.57-71
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• 2022

The purpose of this study was to analyze the perception and demand of local youth and to find ways to support universities in order to create an youth start-up ecosystem. To this end, 509 young people living in Seoul were analyzed to recognize and demand young people in the region for youth start-ups, and to support universities. The findings are as follows. First, as a result of analyzing young people's perception of youth start-ups in the region, the "Youth Start-up Program" was analyzed the highest in terms of the demand for regional programs by university. In addition, there was a high perception that the image of youth startups in the region was "challenging" and "good for changing times." Second, after analyzing the demand for support for youth start-ups in the region, it appeared in the order of mentoring, start-up education, and creation of start-up spaces. And it showed different needs for different ages. Third, the results were derived from analysis of the demand for university support for the creation of a regional youth start-up ecosystem, the criteria for selecting local youth start-up support organizations, and the period of participation in local youth start-up support. Based on the results of the above research, the implications and suggestions of university support for the creation of a community of youth start-up ecosystem are as follows. First of all, it is necessary to develop and operate sustainable symbiosis mentoring programs focusing on university's infrastructure and regional symbiosis. Second, it is necessary to develop and utilize step-by-step systematic microlearning content based on the needs analysis of prospective youth start-ups. Third, it is necessary to form an open youth start-up base space for local residents in universities and link it with the start-up process inside and outside universities. The results of this study are expected to be used as basic data for establishing policies for supporting youth start-ups and establishing and operating strategies for supporting youth start-ups at universities.