• 방사성폐기물학회지
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• 제20권4호
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• pp.429-453
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• 2022

Numerical modeling and scenario composition are needed to characterize the geological environment of the disposal site and analyze the long-term evolution of natural barriers. In this study, processes and features of the hydro-mechanical behavior of natural barriers were categorized and represented using the interrelation matrix proposed by SKB and Posiva. A hydro-mechanical coupled model was evaluated for analyzing stress field changes and fracture zone re-activation. The processes corresponding to long-term evolution and the hydro-mechanical mechanisms that may accompany critical processes were identified. Consequently, practical numerical methods could be considered for these geological engineering issues. A case study using a numerical method for the stability analysis of an underground disposal system was performed. Critical stress distribution regime problems were analyzed numerically by considering the strata's movement. Another case focused on the equivalent continuum domain composition under the upscaling process in fractured rocks. Numerical methods and case studies were reviewed, confirming that an appropriate and optimized modeling technique is essential for studying the stress state and geological history of the Korean Peninsula. Considering the environments of potential disposal sites in Korea, selecting the optimal application method that effectively simulates fractured rocks should be prioritized.

• 설비공학논문집
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• 제15권8호
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• pp.674-682
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• 2003

Natural gas hydrate typically contains 85 wt.% water and 15 wt.% natural gas, and commonly belongs to cubic structure I and II. Also, 1m$^3$ hydrate of natural gas can be decomposed to 200 m$^3$ natural gas at standard condition. If this characteristic of hydrate is reversely utilized, natural gas is fixed into water and produced to hydrate. Therefore the hydrate is great as a means to transport and store natural gas. So, the tests were performed on the formation of natural gas hydrate is governed by the pressure, temperature, gas composition etc. The results show that the equilibrium pressure of structure II is approximately 65% lower and the solubility is about 3 times higher than structure I. Also if the subcoolings of structure I and structure II are more than 9 K and 11 K respectively, the hydrates are rapidly formed.

• 한국유기농업학회지
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• 제8권1호
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• pp.101-109
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• 1999

In order to investigate the possibility of treating the different mixture ratios of apple pomace and nightsoil sludge by vermicomposting was performed and the stability of worm casts, and availability of worm casts as plant growth media was evaluated by the analysis of chemical composition. The results were obtained as follows ; 1. The value of cast production at 100% apple pomace treatment was higher than those of other mixture ratios of apple pomace and nightsoil sludge. 2. The highest values of increasing rate and reproductive efficiency were obtained at mixture ratios of 60% apple pomace with 40% nightsoil sludge. 3. The value of increasing rate at 100% nightsoil sludge treatment was lower that those of other mixture ratios of apple pomace and nightsoil sludge. 4. Organic matter, available inorganic nutrients and stability of worm casts showed high values in all treatments. It means that worm casts are an excellent plant growth media source with a high chemical composition and their stability.

• Ocean and Polar Research
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• 제36권3호
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• pp.209-223
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• 2014

The community structure of benthic meiofauna was investigated from seasonal surveys at seventeen stations off the Saemangeum area, in 2007. Ten meiofaunal taxa were identified. Nematodes were the dominant faunal group in all seasons and harpacticoids were dominant only at a few stations. The mean density of meiofauna was 383 indiv. $10cm^{-2}$, highest in May and November (434 indiv. $10cm^{-2}$), lowest in February (284 indiv. $10cm^{-2}$). Meiofaunal mean biomass was $80.49{\mu}gC{\cdot}10cm^{-2}$, highest in November ($99.54{\mu}gC{\cdot}10cm^{-2}$), lowest in February ($51.56{\mu}gC{\cdot}10cm^{-2}$). Cluster analysis revealed that the study area was composed of three benthic meiofaunal communities. There were significant correlations between major meiofaunal groups and sediment composition and the concentrations of heavy metals. The abundance of harpacticoids are positively correlated with silt (0.559, p < 0.01) and clay (0.340, p < 0.01), and negatively correlated with sand (-0.548, p < 0.01). Harpacticoids also showed positive correlations with heavy metals. The community structure of meiofauna in the study area varied seasonally in response to the change of sediment composition.

• 한국약용작물학회지
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• 제28권2호
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• pp.95-110
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• 2020

Background: In Korea, Agastache rugosa (Fisch. & C. A. Mey.) O. Kuntze is one of the well-known perennial plants belonging to Lamiaceae. This mint-fragranced plant has long been used for the treatment of abdominal pain, congestion, chills, and diarrhea since the Goryeo Dynasty. Although this plant has various medicinal properties, it is only used as a spice and for landscape purposes. Methods and Results: The objective of this paper was to review the chemical composition and biological properties of the essential oil of A. rugosa. Several studies reported that the essential oil contains more than 60 different chemical components of monoterpene and sesquiterpene hydrocarbons and oxygenated hydrocarbons. The major component is methyl chavicol (estragole), accounting for 64% - 88% of the oil. The chemical composition of this essential oil vaired widely according to the planting time, environmental conditions, planting distance, fertilizer application, and harvesting time. Conclusions: The essential oil of A. rugosa possesses various pharmacological properties such as antioxidant, antibacterial, anticancer, antiviral, nematicidal, antifungal, insecticidal, wrinkle improver, stress reliever, and Alzheimer's disease alleviator. Hence, the essential oil from A. rugosa could be used for the development of high value-added industrial products in the near future.

• 과학교육연구지
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• 제37권2호
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• pp.405-415
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• 2013

이 연구의 목적은 고등학생과 대학생의 글쓰기 교육에 대한 인식을 조사하는 것이다. 이 연구는 광역시 소재의 일반계 고등학교의 자연 계열 318명과 전국 3개 대학에 재학 중인 공학 계열 학생 447명을 대상으로 이공 계열 글쓰기 교육의 현황과 글쓰기 능력에 관련된 설문조사를 실시하였다. 이 연구에서는 이효녕 외(2009)에 의해 개발된 이공계열 글쓰기 설문지를 사용하였으며, 설문조사에서 수집된 자료는 SPSS 18.0 윈도우용 프로그램을 이용하여 다중응답 빈도분석, 기술통계, 독립표본 t검정, 일원분산분석 등을 실시하였다. 고등학생과 대학생의 글쓰기 교육에 대한 기초 인식 조사 결과 고등학생이 대학생보다 글쓰기의 필요성을 상대적으로 적게 느끼는 것으로 나타났다. 또한, 고등학생이 대학생보다 글쓰기에 관한 어려움을 더 적게 느끼는 것으로 나타났다. 글쓰기 교육을 이수한 경험이 있는 대학생의 이수과목은 대부분 기초 글쓰기 과목이고 이공 계열 글쓰기에 대한 과목은 거의 이수하지 않았다. 공학 계열 대학생의 전공별 글쓰기 교육의 활성화를 위한 기초 조사에서 각 전공별로 학생들이 요구하는 글쓰기 교육의 수준이 달랐다. 글쓰기 교육의 전반적인 필요성에서 화학공학 계열이 가장 높았고 기계공학 계열과 전자공학 계열 순으로 나타났다. 고등학교와 대학에서의 글쓰기 교육에 관한 연구는 글쓰기를 가르치는 교사나 교수에 대한 연구, 글쓰기 교육 내용과 교육 방법, 그리고 대학의 전공별 글쓰기 프로그램 개발과 같은 연구로 확장되어야 한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제30권3_4호
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• pp.285-292
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• 2003

기존에 개발된 MPEG-4 플레이어들을 살펴보면, 객체의 삽입, 삭제, 갱신과 같은 사용자 상호작용에 의한 시청각 장면 프리젠테이션시 전체 미디어 객체를 다시 프리젠테이션해야 하므로 화면이 껌뻑이거나 프리젠테이션 속도가 느렸다. 본 논문에서는 이를 개선하기 위해 객체 우선 순위 컴포지션 방법을 제안한다. 이는 복합 미디어 객체로 구성된 시청각 장면을 사용자 상호자용에 의해 실시간으로 객체가 삽입, 삭제, 갱신되는 장면 변화를 보다 효율적으로 프리젠테이션하는 방법이다. 제안된 방법으로 구현한 결과는 MPEG-4 스트림의 즉각적이고 자연스러운 프리젠테이션이 가능함을 보여준다

• Natural Product Sciences
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• 제25권2호
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• pp.81-91
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• 2019

Marrubium vulgare, plant species belonging to Marrubium genus, is widespread in the Mediterranean areas, introduced elsewhere and also cultivated in many countries. Its oil is recognized to possess a considerable biological activities with varied chemical composition. This paper aims to overview the chemical composition and biological activities of M. vulgare essential oil's considered as a medicinal plant, widely used in folk medicine overall the world. In essential oils of M. vulgare, germacrene D, ${\beta}$-caryophyllene, ${\beta}$-bisabolene, bicyclogermacrene and carvacrol are generally considered as either mains or minor constituents and each species presents its own composition. Sesquiterpenoids were the dominant fraction while monoterpenoids were present in appreciable or in trace amount. Oxygenated fractions dominated in monoterpenes however, hydrocarbon fraction overpowered in sesquiterpenes. These oils are biologically active, they exhibit an antioxidant and antimicrobial activities and other activities. Due to the variability of composition of essential oil, further studies are necessary, particularly regarding their chemical's which may cause an important change in the biological activities of oils and probably defined different chemotype.

• 한국표면공학회지
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• 제26권6호
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• pp.334-340
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• 1993

The physico-chemical properties and characteristics after thermal treatment of natural zeolite from Kampo area were studied. The physico-chemical properties of natural zeolite were studied by investigating chemical composition, x-ray diffraction pattern(XRD), scanning electronic microscope(SEM), infrared spec-tra(IR), thermal analysis(TA), and cation exchange capacity(C.E.C.), and the characteristics of natural zeo-lite after thermal treatment from $400^{\circ}C$ to $900^{\circ}C$ were compared with the natural zeolite. This study showed that clinoptilolite was the predominant costituent in natural zeolite, and the natural zeolite contained a little amount of quartz and feldspar as impurities. Zeolite mineral was seen to develop slowly by the natural alternation of volcanic ash considering the almost amorphous crystal structure. The more temperature of ther-mal treatment increased, the more adsorption capacity decreased, considering the fact that the hydroxy peak diminished on infrared spectra, and that cation exchange capacity also decreased distinctly.

• 생약학회지
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• 제7권3호
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• pp.191-193
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• 1976

It has been known that ginseng extract contains several polyacetylene components. But we found only two polyacetylene components in the freshly prepared ginseng extract. Long-term preservation of ginseng or ginseng extract produced many artifact polyacetylenes. The ratio of artifact/genuine polyacetylene was determined by TLC-densitometry on long-term preserved ginseng samples. The results indicated that the ratio was increased proportionally with the span of preservation.