• Journal of Forest and Environmental Science
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• 제37권3호
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• pp.226-234
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• 2021

Two species, P. pyrifolia and P. ussuriensis, of the genus Pyrus native to Korea, are valuable genetic resources that can be used for food, dietary supplement, pharmaceutical, and cosmetics. Bioactive compounds of the plant leaves are the main components that are used for the products. Farmers had cultivated a few individuals from the wild to produce fruits or leaves for traditional remedy or tea; however, bioactive components of their leaves are not tested. We selected some trees from the natural stand that have distinct traits for the improvement program. We investigated the bioassay on the extracts' bioactive compounds and antioxidant capacity from the selected accessions and other accessions, including newly developed cultivars. The contents of the phenolic compounds and flavonoids from the leaf extracts of the selected accessions were higher than the commonly cultivated trees in both species but lower than 'Sanhyang' in P. ussuriensis. The antioxidant capacity was measured using two assay methods, DPPH and ABST. The selected cultivars also had higher inhibitory activity than common trees. The selected accession 'Cultivar 3' in P. pyrifolia had the highest radical scavenging activity than others. Although leaves of the accessions were used only in this study, all three selected individuals have the potential for cultivar in containing high bioactive compounds and antioxidant capacity.

• Wind and Structures
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• 제22권1호
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• pp.65-87
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• 2016

The wind velocity profile over the height of a structure in high intensity wind (HIW) events, such as downbursts, differs from that associated with atmospheric boundary layer (ABL) winds. Current design codes for lattice transmission structures contain only limited advice on the treatment of HIW effects, and structural design is carried out using wind load profiles and response factors derived for ABL winds. The present study assesses the load-deformation curve (capacity curve) of a transmission tower under modeled downburst wind loading, and compares it with that obtained for an ABL wind loading profile. The analysis considers nonlinear inelastic response under simulated downburst wind fields. The capacity curve is represented using the relationship between the base shear and the maximum tip displacement. The results indicate that the capacity curve remains relatively consistent between different downburst scenarios and an ABL loading profile. The use of the capacity curve avoids the difficulty associated with defining a reference wind speed and corresponding wind profile that are adequate and applicable for downburst and ABL winds, thereby allowing a direct comparison of response under synoptic and downburst events. Uncertainty propagation analysis is carried out to evaluate the tower capacity by considering the uncertainty in material properties and geometric variables. The results indicated the coefficient of variation of the tower capacity is small compared to those associated with extreme wind speeds.

• 한국군사과학기술학회지
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• 제18권4호
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• pp.402-408
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• 2015

Protection against direct projectiles has been adapted just to the main command posts in the existing protective facility standards. However, protective capacity for the shelters against direct projectiles is also required because the initial survivability as well as the operation sustainment of the shelters is critical during a couple of days from outbreak of war. In this study, the Russian artillery is used to determine the existing and future threat of the North Korean Armed Forces indirectly. And then, required protective capacity of military shelters in the contact areas is calculated along with UFC 3-340-02 and it is verified using modeling and simulation. Based on the assessed capacity, actual inspect of military facilities with contact areas on spot is performed whether military shelters have enough protection capacity against determined threats. According to the field study, it is verified that proper earth bermed shelter has enough protection capacity. The results in this study could be used how to retrofit the current shelters in the contact areas.

• 기술혁신학회지
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• 제21권1호
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• pp.354-384
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• 2018

본 연구는 사회적 자본의 관점에서 혁신중개인과 기업과의 관계가 흡수역량에 어떠한 영향을 미치는지 분석한다. 그리고 기업의 혁신환경요인은 이 과정에서 직 간접적으로 흡수역량에 어떠한 영향을 미치는지에 대해 연구한다. 이를 위해 국내 대표적인 혁신클러스터인 대덕연구개발특구 내 입주하고 있는 200여개 기업을 대상으로 실증분석을 수행함으로써 제시한 연구질문을 검증하고자 한다. 주요 연구결과는 기업이 활용하고 있는 혁신중개인의 관계와 혁신환경요인이 흡수역량과의 관계에서 전반적으로 유의한 정(+)의 효과가 있음을 보여준다. 세부적으로 혁신중개인의 관계 중에서 신뢰도 및 소통빈도는 흡수역량에 유의한 영향을 미치며, 반면에 지리적 근접성에 대해서는 유의하지 않은 것으로 분석되었다. 또한, 혁신중개인이 기업의 흡수역량에 미치는 영향에서 기업이 직면하고 있는 혁신환경요인은 정(+)의 조절역할을 하며, 하위차원에서는 사회적 요인이 뚜렷하고 긍정적인 영향을 미친다는 사실을 조명하고 있다. 본 연구는 기업의 기술혁신과정에서 혁신중개인의 역할과 흡수역량의 선행요인으로서의 혁신중개인의 중요성과 더불어 혁신환경요인의 중요성 대한 이해에 기여한다.

• 한국지반공학회논문집
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• 제16권3호
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• pp.57-65
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• 2000

다층의 지오그리드로 보강된 사질토 지반에 축조된 줄기초의 극한 지지력을 결정하기 위하여 실내모형실험을 실시하였다. 한가지 종류의 사진토와 지오그리드를 사용하였으며, 시험은 기초의 근입깊이(Df)가 없을 때와 근입깊이(Df)가 있을 때로 분류하여 시행되었다. 기초의 근입깊이(Df)는 기초의 폭(B)보다 작도록 제한되었다. 시험결과, 주어진 보강깊이의 두께에 대하여 지지력비(BCR)는 기초의 근입깊이(Df)가 0보다 클 때 증가하였다.

• 한국환경과학회지
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• 제11권8호
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• pp.773-781
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• 2002

The natural carbon cycle has been perturbed since the mid-19th century by anthropogenic CO$_2$emissions from fossil fuel combustion and deforestation due to population growth and industrialization. The current study simulated the global carbon cycle for the past 42 years using an eight-box carbon cycle model. The results showed that since the terrestrial biospheric carbon sink was roughly offset by the deforestation source, the fossil fuel emission source was partitioned between the atmospheric and oceanic sinks. However, the partitioning ratio between the atmosphere and the ocean exhibited a change, that is, the carbon accumulation rate was faster in the atmosphere than in the ocean, due to a decrease in the so-called ocean buffering capacity. It was found that the ocean buffering capacity to take up excess CO$_2$decreased by 50% in terms of the buffer factor over the past 42 years. Accordingly, these results indicate that if the current CO$_2$emission trend continues, the future rate of increase in the atmospheric CO$_2$concentration will accelerate.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.533-538
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• 2009

Ultimate lateral loaded pile capacity is influenced by soil conditions. Methods of calculating ultimate lateral loaded pile capacity in homogeneous soil were suggested by a lot of previous researchers.(Broms 1964, Petrasovits & Award 1972, Prasad & Chari 1999) There is only few homogeneous soil in actual condition, however, it could be not conviction that the methods from previous researchers are correct in multi-layered soil. In this study, ultimate lateral capacities were estimated from artificial multi-layered soils and were measured from lateral load test that were composed by various soil conditions. The influence of layered soil conditions were confirmed by comparing with two results.

• Steel and Composite Structures
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• 제33권2호
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• pp.181-194
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• 2019

This paper presents an efficient approach to generate a new empirical formula to predict the axial compression capacity (ACC) of circular concrete-filled tube (CCFT) columns using the artificial neural network (ANN). A total of 258 test results extracted from the literature were used to develop the ANN models. The ANN model having the highest correlation coefficient (R) and the lowest mean square error (MSE) was determined as the best model. Stability analysis, sensitivity analysis, and a parametric study were carried out to estimate the stability of the ANN model and to investigate the main contributing factors on the ACC of CCFT columns. Stability analysis revealed that the ANN model was more stable than several existing formulae. Whereas, the sensitivity analysis and parametric study showed that the outer diameter of the steel tube was the most sensitive parameter. Additionally, using the validated ANN model, a new empirical formula was derived for predicting the ACC of CCFT columns. Obviously, a higher accuracy of the proposed empirical formula was achieved compared to the existing formulae.

• 한국물환경학회지
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• 제27권6호
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• pp.841-847
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• 2011

In this study, a method to determine the design capacities of nonpoint source (NPS) pollutant treatment facilities in urban areas was suggested. A facility capacity to treat 80 percent of total SS discharge was estimated by 2-year rainfall - runoff - build-up and wash-off simulation at Goonja drainage district in Seoul. For wash-off simulation, four wash-off models (EMC, RC, EXP, and Joo model) were used. As the results, 80 percent of total SS discharge could be treated with only 7.7~31.4% facility capacity of peak flow. The suggested method and results will provide a guideline to determine design capacities of NPS pollutant treatment facility in urban areas.

• 한국습지학회지
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• 제19권4호
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• pp.523-532
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• 2017

도시 및 환경문제는 인간의 과도한 활동으로 인한 귀중한 자원의 무분별한 남용과 생태계의 자생적 회복 속도보다 더 빠른 소비에서 발생한다. 이에 따라 도시 및 환경 분야에서는 생태계의 수용 능력 범위 즉 생태적 환경용량 내에서 개발이 이루어질 수 있도록 다양한 계획과 실천 전략이 수립되고 있다. 본 연구에서는 아산시를 대상으로 생태발자국 모델을 통해 생태적 환경용량을 산정하였다. 아산시의 2015년 생태발자국 및 생태적자는 각각 5.12(gha/인), -4.99(gha/인)로 산정되었으며, 2001년부터 2015년까지의 생태발자국 증가율은 81%이며 생태적자는 같은 기간에 190%로 급증하였다. 이러한 결과는 아산시의 인구증가와 도시개발에 따른 자원소비가 지속적으로 증가하고 있고, 환경용량의 한계치에 영향을 주는 녹지와 농지, 습지 등의 생태적 공간의 감소는 더욱 가속화되고 있는 것을 보여준다. 아산시의 지속가능한 발전을 위해서는 녹지와 농지, 습지 등을 보전하고 생태적 환경용량을 고려하여 도시개발 및 성장을 유도하는 것이 필요하다. 본 연구에서는 아산시를 대상으로 환경용량 범위 안에서 도시 성장을 유도할 수 있도록 생태적자를 활용한 방안을 제안하고자 한다.