• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.383-392
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• 2007

Karstic features and mining-related cavities not only lead to severe restrictions in land utilizations, but also constitute serious concern about geohazard and groundwater contamination. A microgravity survey was applied for detecting, mapping and monitoring karstic cavities in the test site at Muan prepared by KIGAM. The gravity data were collected using an AutoGrav CG-3 gravimeter at about 800 stations by 5 m interval along paddy paths. The density distribution beneath the profiles was drawn by two dimensional inversion based on the minimum support stabilizing functional, which generated better focused images of density discontinuities. We also imaged three dimensional density distribution by growing body inversion with solution from Euler deconvolution as a priori information. The density image showed that the cavities were dissolved, enlarged and connected into a cavity network system, which was supported by drill hole logs. A time-lapse microgravity was executed on the road in the test site for monitoring the change of the subsurface density distribution before and after grouting. The data were adjusted for reducing the effects due to the different condition of each survey, and inverted to density distributions. They show the change of density structure during the lapsed time, which implies the effects of grouting. This case history at the Muan test site showed that the microgravity with accuracy and precision of ${\mu}Gal$ is an effective and practical tool for detecting, mapping and monitoring the subsurface cavities.

• Journal of Korean Home Economics Education Association
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• v.31 no.1
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• pp.115-136
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• 2019

The purpose of this study is to analyze the contents of 'housing' unit in middle school Technology-Home Economics textbooks according to the 2015 revision curriculum based on the targets of SDGs. All contents of the ten textbooks of five publishers, such as texts, photographs/figures/tables, activity tasks, and supplementary materials were analyzed in terms of SDGs targets. The number of 'housing' contents among 4 small housing units of Technology-Home Economics book 1 & 2 varied from 64 to 97 by publishers. Beside SDGs4.7, which contains inclusive and general ESDGs, 24 targets of 10 SDGs were found to be related to the contents of 'housing' and were grouped into 15 target categories. The number of SDGs target categories related to housing contents of each small unit and total of all units differed by publishers. Each of 4 small 'housing' units from all the five publishers was related to 6~10 target categories. The contents of five book 1's were related to smaller number of target categories than those of five book 2's. They corresponded to 9 and 12 target categories, consecutively. Only SDGs' target11.1 (appropriate and safe housing and basic services) was related to all the four small units of 'housing' contents among all the five publishers. covering 43.8% of the housing contents. In conclusion, the contents of the 'housing' unit were related to broad range of SDGs targets. Further study could relate goals of teaching-learning plan to various global targets of SDGs according to the contents of 'housing' in order to accomplish ESDGs.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.1
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• pp.38-47
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• 2013

This study was performed in order to preserve and protect the scenic sites and surrounding environment is located in the Urban Residential Area. After classifying the type of area surrounding parcels of Seongbuk-dong is located in Seongragwon, Satisfaction Survey, scenic sites designated areas for residents living near the analyzed. Research methods, Cadastral research, literature survey, field survey, and the survey was conducted. Cultural heritage awareness about the collected questionnaires of frequency analysis, and reliability analysis for cultural heritages around satisfaction, satisfaction analysis by parcel area, parcel area for the verification of specific differences regression analysis for the full-on relationship satisfaction, one-way ANOVA was conducted for each. Overall Cultural awareness analysis results, the residence is located close to the Seoul Seonjamdanji, Seongragwon, Simujang, Sanghoe Lee Tae-Joon's houses, Seoul Hanyang castle showed that cultural heritage were know unfulfilled cultural heritage. The purpose of cultural heritage visit was to break/walks. Preservation was usually level and there is no inconvenience caused as a cultural heritage. Regulatory intensity level was usually level and showed a positive reaction to the impact of cultural heritage in Seongbuk-dong image mostly. cultural heritage have a positive impact on the image of the town. but access to cultural heritage is not easy and doesn't affect the life is expected. Overall satisfaction for cultural heritages in the surrounding space, the larger the size of the lot, and higher satisfaction. Seongbuk-dong most of the residents satisfaction was higher. Small lots of residents showed low satisfaction for safety when walking at night, heritage value rise, private ownership of heritage use, harmony with surrounding environment, Building exterior, non-physical uniqueness like culture art mental. It can be interpreted that small lots of residential environment quality is low compared to the large lots, influx of residents in other regions due to the redevelopment of one of Seongbuk-dong, private ownership of heritage use. And generally lower satisfaction on the harmonization of the facility(street lights, signs, etc.). Therefore cultural heritage signs for facility expansion, cultural educational programs, will be needed to maintain the uniqueness village when scenic sites in the city center around the area of management strategy.

• Journal of the Korean Electrochemical Society
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• v.23 no.2
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• pp.25-38
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• 2020

Photoelectrochemical water splitting has been considered as the most promising technology for generating hydrogen energy. Transition metal dichalcogenide (TMD) compounds have currently attracted tremendous attention due to their outstanding ability towards the catalytic water-splitting hydrogen evolution reaction (HER). Herein, we report the synthesis method of various transition metal dichalcogenide including MoS₂, MoSe₂, WS₂, and WSe₂ nanosheets as excellent catalysts for solar-driven photoelectrochemical (PEC) hydrogen evolution. Photocathodes were fabricated by growing the nanosheets directly onto Si nanowire (NW) arrays, with a thickness of 20 nm. The metal ion layers were formed by soaking the metal chloride ethanol solution and subsequent sulfurization or selenization produced the transition metal chalcogenide. They all exhibit excellent PEC performance in 0.5 M H₂SO₄; the photocurrent reaches to 20 mA cm^-2 (at 0 V vs. RHE) and the onset potential is 0.2 V under AM1.5 condition. The quantum efficiency of hydrogen generation is avg. 90%. The stability of MoS₂ and MoSe₂ is 90% for 3h, which is higher than that (80%) of WS₂ and WSe₂. Detailed structure analysis using X-ray photoelectron spectroscopy for before/after HER reveals that the Si-WS₂ and Si-WSe₂ experience more oxidation of Si NWs than Si-MoS₂ and Si-MoSe₂. This can be explained by the less protection of Si NW surface by their flake shape morphology. The high catalytic activity of TMDs should be the main cause of this enhanced PEC performance, promising efficient water-splitting Si-based PEC cells.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.169-179
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• 2011

There are two types of nuclear reactors in Korea and they are PWR type and CANDU type. The safe management of the spent fuels from these reactors is very important factor to maintain the sustainable energy supply with nuclear power plant. In Korea, a reference disposal system for the spent fuels has been developed through a study on the direct disposal of the PWR and CANDU spent fuel. Recently, the research on the demonstration and the efficiency analyses of the disposal system has been performed to make the disposal system safer and more economic. PWR spent fuels which include a lot of reusable material can be considered being recycled and a study on the disposal of HLW from this recycling process is being performed. CANDU spent fuels are considered being disposed of directly in deep geological formation, since they have little reusable material. In this study, based on the Korean Reference spent fuel disposal System (KRS) which was to dispose of both PWR type and CANDU type, the more effective CANDU spent fuel disposal systems were developed. To do this, the disposal canister for CANDU spent fuels was modified to hold the storage basket for 60 bundles which is used in nuclear power plant. With these modified disposal canister concepts, the disposal concepts to meet the thermal requirement that the temperature of the buffer materials should not be over $100^{\circ}C$ were developed. These disposal concepts were reviewed and analyzed in terms of disposal effective factors which were thermal effectiveness, U-density, disposal area, excavation volume, material volume etc. and the most effective concept was proposed. The results of this study will be used in the development of various wastes disposal system together with the HLW wastes from the PWR spent fuel recycling process.

• Journal of Environmental Impact Assessment
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• v.24 no.6
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• pp.561-577
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• 2015

The heavy metal accumulations of avian eggshells were studied in order to test a feral pigeon (Columba livia)'s eggshell as an indicator for the environmental monitoring of pollutants. The reviews on the eggs of the different 19 avian species showed that it is the eggshell rather than the egg content that can better reflect the heavy metals in the environment; in most cases the CVs (coefficients of variations) of the heavy metal concentrations in the eggshells were higher than those in the egg contents. This can indicate that the heavy metal accumulations are homeostatically controlled in the egg contents, but the accumulations in the eggshells are varied according to the environmental conditions. To test the reviews, the feral pigeon eggs from the two different sites, one representing urban and the other rural environment, were analyzed for lead (Pb) and cadmium (Cd). The result showed that the eggshells of the urban pigeons (Hangang) had the higher metal concentrations than those of the rural pigeons (Hampyeong). The same difference can also be found in the internal organs (liver, bone) and blood. However, the analyses of the egg contents between the two sites did not reveal the differences. In other words, the result suggests that the feral pigeons, like the other avian species, are able to control the heavy metals into the egg contents homeostatically. Therefore, it is more useful to use the feral pigeon eggshell rather than the egg content in case of monitoring heavy metals in different habitats.

• The Korean Journal of Air & Space Law and Policy
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• v.28 no.2
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• pp.259-294
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• 2013

After its experiment involving the exploding of a satellite in space in 2007, China proudly aired news on TV and ran articles in newspapers. However, the event was internationally criticized and drew widespread attention. Many countries denounced the explosion by pointing out that it could be part of the nation's plan to expand its military power to space or that it could pose a danger to the peaceful use of space. However, there is no talk of whether the experiment that produced a huge amount of space debris could have violated an international law, namely the Outer Space Treaty. Although space garbage has been said to be a serious problem, the amount is still on the increase. If we continue to launch new space launch vehicles into orbit at this rate, we will not be able to use it anytime soon like we do today. As the commercial use of space is likely to increase, the situation will certainly get worse. The international community is fully aware of the seriousness of the problem and working together to reduce the amount of space garbage. However, despite the fact that the United States and Soviet Union's ASAT(Anti-Satellite) programs have been implemented for a long time, there have been no complaints about them in terms of military expansion or breach of the Outer Space Treaty. Also, the recent Chinese test is largely viewed to be in accordance with international law. A lot of research has been undertaken with regard to the problem of space garbage. Now people's awareness of dangers being posed has been fully raised. Under the circumstances, the dismissing of China's satellite smashing, leaving a big mess in its wake, as nothing more than an experiment, is a red flag to, if not many, at least some people. By means of this thesis, I would like to review whether the Chinese test has violated an international space law. This thesis presents an overview of the issues surrounding the event and examines the possibility of violating the Outer Space Treaty, formally the Treaty on Principle Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies. After the China test, the UN Scientific and Technical Subcommittee first adopted space debris mitigation guidelines, I'll introduce the content of the guidelines and discuss the characteristics of the guidelines and what can be done to address the issue.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.479-487
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• 2018

The purpose of this study is to analyze photochemical activity of nursery seedlings under drought stress, using chlorophyll fluorescence reaction analysis. Young nursery seedlings of tomato (Lycopersicon esculentum Mill.) and cucumber (Cucumis sativa L.), were grown under drought stress for 8 days. Analysis of chlorophyll fluorescence reaction (OJIP) and parameters, were performed to evaluate photochemical fluctuation in nursery seedlings under drought stress. Chlorophyll fluorescence reaction analysis showed maximal recorded fluorescence (P) decreased from the 5 day after treatment in tomato seedlings, while an amount of chlorophyll fluorescence increased at the J-I step. Thus, physiological activity was reduced. In cucumber seedlings, maximal recorded fluorescence (P) and maximal variable fluorescence ($F_V$) lowered from the 4 day after treatment, and chlorophyll fluorescence intensity of J-I step increased. Chlorophyll fluorescence parameter analysis showed electron transfer efficiency of PSII and PSI were significantly inhibited with decreasing $ET2_O/RC$ and $RE1_O/RC$ from the 5 day after treatment, in tomato seedlings and from the 4 day after treatment, in cucumber seedlings. $ET2_O/RC$ and $PI_{ABS}$ significantly changed. In conclusion, 6 indices such as $F_V/F_M$, $DI_O/RC$, $ET2_O/RC$, $RE1_O/RC$, $PI_{ABS}$ and $PI_{TOTAL}ABS$ were selected for determining drought stress in nursery seedlings. Drought stress factor index (DFI) was used to evaluate whether the crop was healthy or not, under drought stress. Cucumber seedlings were less resistant to drought stress than tomato seedlings, in the process of drought stress.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.87-105
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• 2009

Nonlinear dynamic deformation characteristics, expressed in terms of normalized shear modulus reduction curve (G/$G_{max}-\log\gamma$, G/$G_{max}$ curve) and damping curve (D-$\log\gamma$), are important input parameters with shear wave velocity profile ($V_s$-profile) in the seismic analysis of (new or existing) fill dam. In this paper, the reasonable and economical methods to evaluate the nonlinear dynamic deformation characteristics for core zone and rockfill zone respectively are presented. For the core zone, 111 G/$G_{max}$ curves and 98 damping curves which meet the requirements of core material were compiled and representative curves and ranges were proposed for the three ranges of confining pressure (0~100 kPa, 100 kPa~200 kPa, more than 200 kPa). The reliability of the proposed curves for the core zone were verified by comparing with the resonant column test results of two kinds of core materials. For the rockfill zone, 135 G/$G_{max}$ curves and 65 damping curves were compiled from the test results of gravelly materials using large scale testing equipments. The representative curves and ranges for G/$G_{max}$ were proposed for the three ranges of confining pressure (0~50 kPa, 50 kPa~100 kPa, more than 100 kPa) and those for damping were proposed independently of confining pressure. The reliability of the proposed curves for the rockfill zone were verified by comparing with the large scale triaxial test results of rockfill materials in the B-dam which is being constructed.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.1
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• pp.59-70
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• 2013

This study was to suggest cultural landscape preservation, value creation, as well as utilization plan to help landscape development of Hahoe village by identify the existence of Okyeonsipyeong(玉淵十詠) natural features, which were set around Buyongdae(芙蓉臺) in Hahoe Village by Seoae(西崖) Ryu, Seongryong(柳成龍), and understanding their characteristics and meanings of natural features and meanings. Based on the writings of "Okyeonseodanggi" and "Okyeonsipyeong", the major results of this study are as belows. 'Okyeon(玉淵)' letters carved on the rocks, also known as the name of pavilion in Okyeonjeongsa(玉淵精舍), is the center of Okyeonsipyeong that symbolizes the enlightenment of clean noble man, as well as the symbolic locational expression of studying room. One of Okyeonsipyeong, 'Wansimjae', is assumed to be the name from the combination of two Buddhist names, 'Wanjeok(玩寂)' and 'Seshim(洗心)', 'Dangho(堂號)', lined on both sides with Wonlakjae, the residence of Seoae, as the center. Wansimjae is after all the natural feature indicating the overall Okyeonjeongsa as the core of Okyeonsipyeong with west edge Gyeomamjeongsa(謙巖精舍). Among ten Okyeonsipyeong natural features, Wansimjae(玩心齋), Ganjukmun(看竹門), Gyeomamsa(謙菴舍), Dalgwandae(達觀臺), Ssangsongae(雙松厓), and Dohwacheon (桃花遷) are on the right side of the stairway from Okyeonjeongsa to Gyeomamjeongsa, while Chuwoldam(秋月潭), Neungpadae(凌波臺), Gyeseonam(繫船巖), and Jijuam(砥柱巖) are on the road to the cliff under river cliff in Buyongdae as well as to the dock, and all are located within 500m radius close and diameter area. As the results of lexeme and context analyses of Okyeonsipyeong poet, they are mainly about Confucian teachings symbolizing the constancy of the classical scholar including ego becoming one with the nature and back to the nature, unworldliness and farsighted view, transcendence and seclusion, as well as integrity spirit. In Dohwacheon and Gyeomamsa poets, there is Tao characteristics and brotherhood that pursue fairylands such as Mooreungdowon(武陵桃源). To create tourism brand and landscape of Okyeonsipyeong, it is necessary to prepare storytelling plans including the letters carved on the rocks introduction in Buyongdae area, and also synopsis of the Silgyeongsusang musical, 'Buyongjiae(芙蓉之愛)' that is related to 10 natural features. In addition, the related plans of the experience road from Gyeseonam, which is the boat stop in Buyongdae, to Ganjukmun of Okyeonjeongsa, and again to viewing routes on the stairways to Gyeomamjeongsa using boats are necessary. For preliminary preservation and maintenance plans, the safety of the stairway from Okyeonjeongsa to Gyeomamjeongsa should be secured, the rock inscription should be preserved, landscape interpretation plates should be installed, trees and shrubs around Dohwacheon rock inscription should be removed, Dalgwandae letters carved on the rocks should be restored, and the bamboo forest outside Ganjukmun as well as Prunus persica plantation around Dohwacheon should be pointed out.