• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.316-316
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• 2020

1970년대 이후 급속한 경제성장과 함께 도시화와 산업구조의 변화로 인간 활동과 밀접한 관계를 맺고 있는 수환경은 크게 훼손되어 왔다. 특히 인간 활동으로 인한 대량 생산과 소비는 하천의 자정작용을 초과하는 오염물질을 배출하고 오염된 하천은 본래 기능을 상실하였으며 각종 생활 오·폐수의 배수구로서의 역할이 부여되어 대부분 복개되기에 이르렀다. 이처럼 현재 우리나라의 하천은 고유의 기능인 용수원으로의 기능과 도시민의 휴식 및 친수공간으로서의 기능을 상실하였으며 중소하천의 건천화에 따른 하천 유지유량의 부족은 하천을 중심으로한 각종 용수의 부족, 수질 오염의 증가, 수변환경 친수기능 상실 등의 문제를 초래하고 있다. 중소하천의 건천화현상은 2000년대 이후 계속 증가, 진행되어 소하천뿐만 아니라 지방하천도 이미 메마르고 있는 상태이며 이로 인한 2차적 비용증가 등 경제적인 측면의 손실도 매년 심해지고 있어 건천화에 대한 원인 규명과 방지책에 대한 연구가 시급한 실정이다. 특히 새만금유역은 농업용수 사용이 많은 유역의 특성상 하천의 건천화 문제가 지적되었으나, 대부분 새만금유역의 용수이용체계 등에 연구가 추진되어 주로 농업용수 이용실태와 수질측정을 위주로 하고 있으며, 건천화의 실태와 원인, 그리고 건천화로 인한 물환경의 영향 등에 대해 조사된 바가 없다. 따라서 본 연구는 만경강유역 하천에 대하여 대조하천, 도시하천, 준도시하천, 농업하천으로 대표지점을 선정하여 현장조사와 유역모델링을 통해 건천화의 원인별 기여율을 파악하였고, 만경강유역의 건천화 규모를 추정하였다. 건천화 원인을 평가하기 위해 유역 내 인위적인 물이용이 없는 상태인 기준유량(자연유량)을 산정하였고, 댐 및 방류량의 영향, 하수처리수 유입에 의한 영향, 수자원이용에 의한 영향, 수리구조물(수자원이용)에 의한 영향의 조건을 고려하였으며 건천화 평가지수를 활용하여 대상하천 소유역의 건천화 현황을 파악하였다. 또한 분석된 결과를 토대로 만경강유역의 토지이용도를 고려하여 만경강유역의 건천화 규모를 추정하였다. 분석결과, 수리구조물(수자원이용)에 의한 영향이 25.5%, 수자원이용에 의한 영향이 13.9%, 방류량에 의한 영향이 12.3%, 하수처리수 유입에 의한 영향이 6.54%로 나타났으며, 수리구조물(수자원 이용)에 의한 영향이 가장 크게 평가되었고, 하수처리수 유입에 의한 영향이 가장 작은 것으로 평가되었다. 이러한 연구결과는 향후 하천의 건천화현상에 대한 원인을 규명하고 방지하기 위한 대책 수립에 필요한 기초자료로 활용이 가능할 것으로 판단된다.

• The Korean Journal of Financial Management
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• v.24 no.1
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• pp.29-58
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• 2007

We develop a model to estimate the value of growth opportunities, which is based on the seminal papers of M&M(1961, 1963) and Lee(2006). Making use of the estimation model, we estimate a new proxy variable of the growth opportunities, other than the usual proxy variables such as quasi Tobin's Q, MBR, and so on. The new proxy variable of growth opportunities can represent a necessary condition to identify whether the increase in new investments are successful or not. The empirical findings on the growth opportunities during the IMF currency crisis period and the post-IMF period are as follows; First, the overall success rate of new investments is as low as 50%, that means only half of the listed firms were increasing new investments when they had the growth opportunities. Second, during the crisis, one third of the listed firms were experiencing negative growth opportunities. However, during the post-IMF period, the growth opportunities on new investments were turned to be positive due to the turnaround efforts of listed firms. Third, the value of intangible assets, which are resulting from the investment of R&D and human capital, are becoming more important than ever. It seems to be true that larger portions of the value of growth opportunities are coming from the intangible assets, not from the increases in new investments of the physical assets.

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.255-265
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• 1999

This study deals with forest soil characteristics and their effects on the trafficability of logging vehicles. The study area is the national experimental forest located in Kwangnung. This site has 20m length and is equally divided by 5 surveying ranges with 4m width, on which a tractor(FIATAGRI) attached with logging boogie can drive in 4 driving types, namely 1time-return unload, 1time-return with load of 780-790kg weight of 3 logs, 5 and 10times-return with same load. After one driving type on all surveying ranges, the soil hardness is surveyed 5 times with 3 several type tools, SHM-1 type, lang penetrometer(L-PNTM), and clegg impact soil tester(CIST). A disturbed degree of cover vegetation and sliding conditions of vehicle are also observed. As results, the soil type of the test site was SC by USCS and dry brown forest soil. The cover vegetation is gotten trambled under driving after 3-5 times-return, shrubs leaves are fully fallen and their bark are peeled, and after 10 times-return the cover vegetations were nearly disappeared. The test vehicle has neither slided nor was overthrown. The wheel tracks in the 1-3 ranges, of which unit weight(gd, gt) is high and soil moisture content(MC) is low, were only 1-2cm deep, but those in the 4-5 ranges, of which the gd, gt is low and the MC is high, were 5-7cm deep. In the soil hardness test, which was established in 5 test ranges by types of driving, the more driving times, the higher the hardness. The soil hardness surveyed by L-PNTM has changed slowly and that surveyed by SHM-1 type has risen sharply. In the ranges with higher specific gravity(Gs), higher unit weight, lower MC and higher liquid limit(LL) and plasticity index(PI) was the soil hardness high and the trafficability was good. In the ranges with opposite conditions, also in the ranges of the lower soil hardness, the trafficability must be not good, because the wheel track may be deep. The results from CIST attached with 4kg hammer was not better than expected. So it is recommended to use CIST with 2.5kg or 0.5kg hammer.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.651-660
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• 2007

Acid drainage has been recognized as an environmental concern in abandoned mine sites for long time. Recently, the environmental and structural damage by acid drainage is a current issue in construction sites in Korea. Here, the author introduces the type of damages by acid drainage in construction sites and emphasizes the importance of geoscience discipline in solving the problem. Metasedimentary rock of Okcheon group, coal bed of Pyeongan group, Mesozoic volcanic rock. and Tertiary sedimentary and volcanic rocks are the major rock types with a high potential for acid drainage upon excavation in Korea. The acid drainage causes the acidification and heavy metal contamination of soil, surface water and groundwater, the reduction of slope stability, the corrosion of slope structure, the damage on plant growth, the damage on landscape and the deterioration of concrete and asphalt pavement. The countermeasure for acid drainage is the treatment of acid drainage and the prevention of acid drainage. The treatment of acid drainage can be classified into active and passive treatments depending on the degree of natural process in the treatment. Removal of oxidants, reduction of oxidant generation and encapsulation of sulfide are employed for the prevention of acid drainage generation.

• Korean Journal of Heritage: History & Science
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• v.44 no.4
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• pp.142-153
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• 2011

'Silla Monument Stone in Jungseong-ri, Pohang' was discovered in Pohang City, Gyeongsangbuk Province of Korea in 2009. The monument stone with irregular shape has dimensions of maximum height of 105cm, width of 47.6~49.6cm, thickness of 13.8~14.7cm and weight of 115kg. The results of monument stone was found to be granitite. Conservation treatment procedure was carried out in the order of production of Weathering map, cleaning of surface pollutants, consolidation using ethyl silicate. Black pollutant(crust) that covered more than 60% of the surface was analyzed first in order to remove the pollutants on the surface of the monumental stone by cleaning of surface pollutants using laser. The purpose on analysis was not only to verify the pollutants on the stone but also to carry out preliminary cleaning by securing rocks with same pollutant as the monumental stone. As the results of analysis using p-XRF(PMI. INNOV-X, USA) on the site, high level of Mn and Fe were detected, and the analysis of small section that had been fallen off with SEM/EDX for the purpose of quantitative analysis also detected high level of Mn. The Similar contaminants on Stone secured in the manner described above were made into 10 samples ($5cm{\times}5cm$) and was subjected to preliminary cleaning by Nd-YAG Laser(Laser&Physics, Korea). The results of surface observation through portable microscope during cleaning revealed that the power of 460mJ, wavelength of 1064nm and irradiation frequency of 1,800~2,300 per $25cm^2$ were most effective. Evaluation on the preservative treatment was made through confirmation of the extent of removal through color-difference meter measurement and component analysis prior to and following removal of the pollutants. As the result of color-difference meter measurement increase in the brightness was evidenced by the increase in the brightness ($L^*$)value from 33 to 49, and it was possible to ascertain the reduction in the pollutants as the content of Mn was reduced by about 80% from $50,000{\pm}5,000ppm$ to $10,000{\pm}2,000pmm$ from the result of component analysis.

• Journal of Conservation Science
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• v.37 no.6
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• pp.723-737
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• 2021

This study analyzed the composition and structure of materials with Buddhist paper scriptures excavated from architectural sites in 'Sum Tolgoi' of the 17^th century and carried out conservation treatment base on the result of the analysis. The scriptures were covered in dust and foreign sub stances, and were so crumpled that it was impossible to identify the form. The damage, loss, and discoloration have been identified. Buddhist scriptures written in Tibetan used indigo and ink sticks on paper as a result of UV-Vis analysis, and ink sticks as black character materials from scriptures written ancient Mongolian. SEM-EDS and Micro-XRF analyses revealed that the outlines were drawn with red lines using a mix of Minium (Pb₃O₄) and Cinnabar (HgS), or Cinnabar (HgS) alone, and the contents of the scriptures were written with silver paint. Silver chloride (AgCl) and Calcium (Ca) were identified in the silver paint component of the characters, while Calcium and Orpiment (As₂S₃) were identified in the yellow lines. Concerning the paper ground, Buddhist scriptures written in ancient Mongolian were characterized by herbal plant fiber and bast fiber, and those written in Tibetan, by bast fiber. Radiocarbon dating indicates that the paper for the scriptures was produced between the 15^th and 17^th centuries. Conservation treatment of the scriptures was carried out based on the experiment on the production of pre-coated paper and how to coat that to prevent the second damage due to the deformation and fragility of the excavated paper. The scriptures were preserved and mounted, and a neutral box was made to identify the contents of the scriptures recorded on both sides after the treatment. This conservation treatment is the result of a study that applied new conservation treatment materials and methods according to the principle of conservation treatment reversibility.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.60-75
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• 2022

The Bayesian algorithm model is a model algorithm that calculates probabilities based on input data and is mainly used for complex disasters, water quality management, the ecological structure between living things or living-non-living factors. In this study, we analyzed the main factors affected Korean Estuary Trophic Diatom Index (KETDI) change based on the Bayesian network analysis using the diatom community and physicochemical factors in the domestic estuarine aquatic ecosystem. For Bayesian analysis, estuarine diatom habitat data and estuarine aquatic diatom health (2008~2019) data were used. Data were classified into habitat, physical, chemical, and biological factors. Each data was input to the Bayesian network model (GeNIE model) and performed estuary aquatic network analysis along with the nationwide and each coast. From 2008 to 2019, a total of 625 taxa of diatoms were identified, consisting of 2 orders, 5 suborders, 18 families, 141 genera, 595 species, 29 varieties, and 1 species. Nitzschia inconspicua had the highest cumulative cell density, followed by Nitzschia palea, Pseudostaurosira elliptica and Achnanthidium minutissimum. As a result of analyzing the ecological network of diatom health assessment in the estuary ecosystem using the Bayesian network model, the biological factor was the most sensitive factor influencing the health assessment score was. In contrast, the habitat and physicochemical factors had relatively low sensitivity. The most sensitive taxa of diatoms to the assessment of estuarine aquatic health were Nitzschia inconspicua, N. fonticola, Achnanthes convergens, and Pseudostaurosira elliptica. In addition, the ratio of industrial area and cattle shed near the habitat was sensitively linked to the health assessment. The major taxa sensitive to diatom health evaluation differed according to coast. Bayesian network analysis was useful to identify major variables including diatom taxa affecting aquatic health even in complex ecological structures such as estuary ecosystems. In addition, it is possible to identify the restoration target accurately when restoring the consequently damaged estuary aquatic ecosystem.

• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.248-257
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• 2006

Total naturalized plant species in the streams of Jeonju were listed as 109 taxa; 24 families, 75 genera, 106 species, 3 varieties. Dividing by stream, Jeonju stream has 75 taxa; 20 families, 55 genera, 73 species, 2 varieties. Samcheon stream has 86 taxa; 19 families, 64 genera, 84 species, 2 varieties. Soyang stream has 80 taxa; 21 families, 60 genera, 77 species, 3 varieties. Urbanization Index (UI) of total streams (109 taxa) was 40.2%. UI was 27.7% in Jeonju stream (75 taxa), 31.7% in Samcheon stream (86 taxa), 29.5% in Soyang stream (80 taxa). Dividing by degree of naturalization classification, 25 taxa (9.2%) were found in class 5, 17 taxa (6.2%) in class 4, 32 taxa (11.8%) in class 3, 27 taxa (9.9%) in class 2 and 8 taxa (2.9%) in class 1. Dividing by introduction period, 48 taxa (44%) aye in period I, 19 taxa (17%) in period II, 42 taxa (39%) in period III. Dividing by growth type, 48 taxa (44%) are annuals, 25 taxa (23%) are biennials, 33 taxa (30%) are perennials. Dividing by the place of origin, 39 taxa (35%) are from Euyope, 33 taxa (30%) from North America, 11 taxa (10%) from Tropic America, 9 taxa (8%) from Europe Asia,5 taxa (5%) from South America, 5 taxa (5%) from China.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.2
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• pp.45-55
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• 1990

This study describes on the erosion control effects of the several grasses and its mixtures for the man-made slopes. The grasses used for this experiment include cool-season grasses such as Festuca rubra L. (Creeping redfescue), Poa pratensis L. (Kentucky bluegrass), Lolium perenne L. (Perenial ryegrass), Lolium multiflorum LAM. (Italian ryegrass), Festuca arundinacea Schrel. (Tall fescue), and warm-season grasses such as Eragrostis curvula Schrad. (Weeping lovegrass), Zoysia japonica Steud. (Zoysiass) and native plants (Artemisia princeps var. orientalis Hara, Lespedeza cuneata G. Don, Arundinella hirta var. ciliata K.) This study was conducted at Dan-kook University from April, 1988 to Octover, 1989. The results are summurized as follows; 1.Cool-season grasses covered the ground quickly in early stage, and weekened slowly during sumer season. Warm-season grasses and native-plants covered the ground slowly in early stage, but during summer season they grew vigorously, so outweighed cool season grasses. 2. The amount of aboveground growth of weeping locearass and underground growth of Artemisia prinoepts are quite differant from others. Since Arumdinella hirta has deep root system, it is thought to very useful protection of unstable for hrdro-seeding. Because cool-season grasses are useful for quick coverage, and native plants or warm-season grow well during summer season with the better compatability to weeds. 3.Mixture III(cool-season and warm-season grasses), mixtureIV(native spp. and Italian ruegrass), and mixtureV(native spp.) resulted in better control of erosion control on man-made slopes. Native spp. has equivallent capacity of erosion control compared to several foreign grasses.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.8 no.4
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• pp.145-159
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• 2013

The purpose of this study is to analyze the structural relationship as to how learning flow and self-directed learning are linked to learning motives and academic self-efficacy in the learning setting of high school students. To accomplish such purpose, based on theoretical backgrounds and preceding research findings evaluation models were put to verification for a valid research model for this study. The initial hypothetical model was that self-directed learning ability would have a direct influence on learning motive, academic efficacy and learning flow, while having an indirect influence on learning flow with learning motive and self-efficacy acting as a mediating variable. But the hypothetical model showed low significance level between self-directed learning and learning motive, and learning motive and learning flow. Therefore, links were adjusted to create the final model within the scope that the adequacy of the model might not be compromised. To verify the model, 900 high school students in Seoul were surveyed and the collected data were statistically analyzed using AMOS v21.0 and SPSS v21.0 But 815 surveys were excluded because they were not sufficiently answered. From the analysis, it was found that self-directed learning and academic efficacy have a direct influence on learning flow while self-directed learning and academic efficacy have an indirect leaning motive and learning flow. This finding means that, in the relationship of self-directed learning and learning flow, learning motive and learning efficacy are positive factors that help high school students experience learning flow. Thus, in order to enhance the experience of self-directed learning ability of high school students, various educational endeavors are needed to draw the experience of learning flow during the regular course of study. In addition, customized educational methods and environments are required to increase academic efficacy of the students.