• Korean Journal of Heritage: History & Science
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• v.54 no.2
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• pp.98-119
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• 2021

This thesis aims to examine when the petroglyphs of Cheonjeon-ri, Ulju were carved and their nature. To achieve this, the relations between rituals and rock carving motifs are examined besides the nature of the archaeological monuments with carved petroglyphs. The investigation revealed that the figurative motifs on the petroglyphs of Cheonjeon-ri, Ulju, may have been carved during the Korean Bronze Age considering other examples of figurative petroglyphs from that period. It is reasonable to assume that the figurative animal motifs on the petroglyphs of Cheonjeon-ri, Ulju were used for rituals of fertility and rebirth as a subsistence ritual during the Korean Bronze Age. The Geomdan-ri Archaeological Culture Type is a strong candidate, having used both petroglyphs of Cheonjeon-ri and those of Bangudae, Ulju, since the Geomdan-ri Archaeological Culture Type has a higher proportion of hunting and fishing and lower proportion of rice cultivation in its subsistence than in the subsistence of the Songguk-ri Archaeological Culture Type. In contrast to the figurative motifs, the abstractive motifs, including the geometric designs on the petroglyphs of Cheonjeon-ri, Ulju, are generally accepted to have been carved during the Bronze Age. Although there have been some disputes over the symbolic meanings of concentric motifs, lozenge motifs, and other geometric motifs, they may be related to rituals for sun worship, ancestor worship, and fertility cults. Their meanings have been continuously reinterpreted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.275-282
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• 2021

High-molecular-weight maleic anhydride-grafted polylactic acids (HMMA-g-PLA) compatibilizers were prepared by melt grafting in a twin screw extruder using di(tert-butyl-perxoyisopropyl)benzene (PK-14; as initiator), maleic anhydride (MA), and divinylbenzene (DVB). To determine the properties of the prepared HMMA-g-PLA compatibilizers, Fourier transform infrared (FTIR), Melt index (MI), and back-titration analyses were performed. On increasing DVB concentration, grafting yield of HMMA-g-PLA increased but MI decreased because 𝛽-scission of PLA was restrained by the DVB, and thus, the molecular weight of HMMA-g-PLA increased. PLA-based wood-plastic composites (WPCs) were prepared using HMMA-g-PLA by melt blending through a single screw extruder. The flexural and impact strengths of WPCs compatibilized with HMMA-g-PLA were greater than those of WPCs produced without HMMA-g-PLA. Scanning electron microscope (SEM) studies indicated that increased mechanical properties were caused by excellent interfacial adhesion between PLA and wood fibers due to the addition of HMMA-g-PLA. However, rather high contents of HMMA-g-PLA reduced the mechanical properties of WPCs. We believe that lower molecular-weight of HMMA-g-PLA added as an compatibilizer, compared with PLA polymer, caused the reduction of mechanical properties.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.61-72
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• 2011

In order to assess hydrologic and nonpoint source pollutant behaviors in a watershed with Soil and Water Assessment Tool (SWAT) model, the accuracy evaluation of SWAT model should be conducted prior to the application of it to a watershed. When calibrating and validating hydrological components of SWAT model, the Nash-Sutcliffe efficiency coefficient (EI) has been widely used. However, the EI value has been known as it is affected sensitively by big numbers among the range of numbers. In this study, a Web-based flow clustering EI estimation system using K-means clustering algorithm was developed and used for SWAT hydrology evaluation. Even though the EI of total streamflow was high, the EI values of hydrologic components (i.e., direct runoff and baseflow) were not high. Also when the EI values of flow group I and II (i.e., low and high value group) clustered from direct runoff and baseflow were computed, respectively, the EI values of them were much lower with negative EI values for some flow group comparison. The SWAT auto-calibration tool estimated values also showed negative EI values for most flow group I and II of direct runoff and baseflow although EI value of total streamflow was high. The result obtained in this study indicates that the SWAT hydrology component should be calibrated until all four positive EI values for each flow group of direct runoff and baseflow are obtained for better accuracy both in direct runoff and baseflow.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.255-260
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• 2011

$NH_4{^+}-{\beta}^{{\prime}{\prime}}$-alumina which is expected to an inorganic solid electrolyte of high temperature polymer electrolyte membrane fuel cells (PEMFC) was prepared by ion-exchange reaction of $K^{+}-{\beta}^{{\prime}{\prime}}$-alumina pellet with $NH_4NO_3$ aqueous solution and molten $NH_4NO_3$ salts as an ion-exchange medium in the autoclave and the heating mentle reaction. In the autoclave reaction, the concentrations of $NH_4NO_3$ solution was chosen at 5 and 10 M. Each ion-exchange reaction was carried out at 130, 150, 170, and $200^{\circ}C$ for 2, 4, 6 and 8 h. In the heating mentle reaction, ion-exchange was performed at $200^{\circ}C$ for 2, 4, 6 and 8 h with molten $NH_4NO_3$ salts. In order to determine the effect of reaction times, each ion-exchange reaction was repeated 3 times. The phase stability and the ion-exchange rate of $NH_4{^+}-{\beta}^{{\prime}{\prime}}$-alumina were analyzed by XRD and ICP.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.425-432
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• 2011

To control non-point source pollution at a watershed scale, rainfall-runoff characteristics from forest watersheds should be investigated since the forest is the dominant land use in Korea. Long-term monitoring would be an ideal method. However, computer models have been utilized due to limitations in cost and labor in performing long-term monitoring at the watersheds. In this study, the Geo-spatial interface to the Water Erosion Prediction Project (GeoWEPP) model was evaluated for its runoff prediction from a coniferous forest dominant watersheds. The $R^2$ and the NSE for calibrated result comparisons were 0.77 and 0.63, validated result comparisons were 0.92, 0.89, respectively. These comparisons indicated that the GeoWEPP model can be used in evaluating rainfall-runoff characteristics. To estimate runoff changes from a coniferous forest watershed with various cover degree scenarios, ten cover degree scenarios (10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%) were run using the calibrated GeoWEPP model. It was found that runoff increases with decrease in cover degree. Runoff volume was the highest ($206,218.66m^3$) at 10% cover degree, whereas the lowest ($134,074.58m^3$) at 100% cover degree due to changes in evapotranspiration under various cover degrees at the forest. As shown in this study, GeoWEPP model could be efficiently used to investigate runoff characteristics from the coniferous forest watershed and effects of various cover degree scenarios on runoff generation.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.491-498
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• 2011

We investigated the ranges of total cellular microcystins content of cyanobacterial blooms collected in Korean lakes and rivers from 2005 to 2009. The amount and composition of microcystins of Korean cyanobacteria varied depending on the sampling water bodies and dominant cyanobacterial genera. Toxic cyanobacterial cell numbers equivalent to $1{\mu}g$ MCYSTs/L using total cellular microcystin content of Korean cyanobacteria were in the range of 2,348 to 66,980,638 cells/mL. Only four samples among forty nine samples showed less cell numbers than current criterion of Harmful Algae Alert System, 5,000 cells/mL indicating current criterion do not reflect properly the microcystins content of Korean cyanobacteria. Anabaena and Aphanizomenon spp. showed three to six times higher cell numbers equivalent to $1{\mu}g$ MCYSTs/L than Microcystis spp. To propose criteria of Harmful Algae Alert System for Korean toxic cyanobacteria, we calculated about 50% selective geometrical means of cyanobacterial cell numbers equivalent to $1{\mu}g$ MCYSTs/L in order of toxic content. The proposed criteria for Microcystis, Oscillatoria, Anabaena, and Aphanizomenon spp., are 10,000, 20,000, 40,000, and 80,000 cells/mL, respectively.

• (The)Study of the Eastern Classic
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• no.71
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• pp.71-98
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• 2018

This study is aimed to figure out the way Yoon Hee-sun perceived the real situations of the society under the Japanese ruling and responded to overcome difficulties in the process of anti-Japanese independence movement. Yoon Hee-sun played an important role as a female activist of the righteous army movement in Kangweon-do and Manchuria. She was a daughter-in-law of Yu Hong-seok, wife of Yu Jae-won, and mother of Yu Don-sang. Three generations of her family had taken the lead in anti-Japanese independence movement. The Yus belonged to a school of 'Hwaseo' and devoted their lives to the independent movement based on the thought of 'wijung chuksa sasang', which means 'defending orthodoxy and rejecting heterodoxy'. They desired to go back to the past and recover as it was rather than building a new society. Therefore, their fights against Japan's invasion were not for establishing a modern nation-state but for recovering the royal authority of the existing order. Both her maiden home and her in-laws belonged to a school of 'Hwaseo' and Yoon Hee-sun couldn't go out of the boundary of her family background. Also, the motivation of her participation in the righteous army movement was based on the confucian values such as loyalty to the king, filial piety and fidelity. In particular, she possessed a high level of self-awareness not only as a wife but also as a woman. On the basis of this, she faced up to reality. For the more effective way of revolt against Japan's invasion, she determined to change the perception of women identified only as a wife of somebody. She thought her duty was to enlighten women through 'education'. As a result, manifestoes and songs supporting the righteous army movement were used as a powerful method.

• (The) Research of the performance art and culture
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• no.34
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• pp.241-276
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• 2017

This paper studies the restoration of Jeongeup notated in Daeakhubo to a singable song. Firstly, the melody of Jeongeup was restored by finding the rhythm of Jeongeup. Secondly, Jeongeup lyric written in Akhakgwebeom was added to the restored melody. Lastly, the musical style of restored Jeongeup song was investigated. The rhythm of Jeongeup was found to be the same as Jinjak's rhythm whose measure consists of four ternary subdivided beats. It is because the Jangdan of Jeongeup contains that of Jinjak. The Jangdan of Jeongeup is played one touch in a measure. Such ternary subdivided beat and one Janggo's touch in a measure were transmitted to today's Sujecheon. The lyric of Jeongeup was added to the restored melody of Jeongeup by following the lyric rules of Jinjak1,2 and Hoengsalmun. The lyric rules of Jinjak 1,2 and Hoengsalmun are as follows. One syllable is sung in two measures, Eodanseongjang 語短聲長 appears, long lasting tunes are mostly applied to Jang of Eodanseongjang 語短聲長, and syllables begin at the first beat in a measure. The musical style of Jeongeup is basically similar to that of Jinjak1, but there are some differences. They are similar in the sense that the melody is very long compared to the lyric and Eodanseongjang 語短聲長 appears. They are different in the sense that Jeongeup uses grace notes rather than Sigimsae when one tune lasts long. Jeongeup in Daeakhubo seems to have undergone changes, and its rhythm is likely to have been expanded two to four times in order to match Mugo dance after being used as an accompaniment to Mugo dance.

• International Area Studies Review
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• v.20 no.1
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• pp.105-125
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• 2016

The expansionary monetary policy was practiced after 2001 in Japan to treat the deflation spiral, and reduced only the nominal interest rates and domestic household demand. One of the most serious factors for this failure was the change of private sector's expectancy. This paper has studied the effect of Japanese monetary policy in 21c., with empirical research based on a renewed macroeconomic model and the VAR. The empirical analysis shows that the effect of monetary policy on the national income during 2001.01-2015.03 is weaker than that of 1985.01-1994.04. Money volume has a diminutive effect on the growth of GDP within a short term after 2001. The change in the expectations of the private sectors might have been the cause of ineffectiveness of the expansive monetary policy. Economic agents learned from the past Japanese financial crisis that an expansive monetary policy increased the inflation rate and caused the 'bubbles to burst' afterwards. The VAR analysis says that the effectiveness of monetary policy on the economic depression declined over the past 20 years and the expansion of money volume has no influence on exchange rate and net export. This means that the expansive monetary policy lost its effect on net export and national income steadily. Monetary policy makers have to recognize this fact, and to consider another anti-cycle political instrument, i.e. the fiscal policy with government debt.

• Journal of the Korean Society of Radiology
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• v.79 no.6
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• pp.303-310
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• 2018

Purpose: To evaluate the CT features of incidental breast lesions on chest CT and to suggest useful criteria for referral to a specialized breast unit. Materials and Methods: Between May 2009 and April 2014, enhanced chest CT examination reports containing the key word 'breast' were reviewed retrospectively. Patients who had incidental breast lesion and were referred to a specialized breast unit and then underwent pathological confirmation or follow-up over a 1-year period were included. Finally, 86 patients (all female, mean age, $48.9{\pm}12.6years$) were enrolled. Two radiologists evaluated lesion characteristics, including size, shape, margins, and enhancement. The correlations between the CT features and pathologies were evaluated, and the diagnostic accuracy of CT features in various combinations was assessed. Results: Among the CT features, irregular shape, non-circumscribed margin, and high contrast enhancement were different between malignant and benign lesions (p < 0.05). The combination of non-circumscribed margin and high contrast enhancement had the highest accuracy (97.7%). Conclusion: Reliable CT features for incidental malignant breast masses are irregular shape, non-circumscribed margin, and high contrast enhancement. The combination of non-circumscribed margin and high contrast enhancement could help distinguish incidental malignant breast lesions and indicate referral to a specialized breast unit.