• 대한수학회지
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• 제42권3호
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• pp.573-597
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• 2005

A continuous linear operator T, on the space of entire functions in d variables, is PDE-preserving for a given set $\mathbb{P}\;\subseteq\;\mathbb{C}|\xi_{1},\ldots,\xi_{d}|$ of polynomials if it maps every kernel-set ker P(D), $P\;{\in}\;\mathbb{P}$, invariantly. It is clear that the set $\mathbb{O}({\mathbb{P}})$ of PDE-preserving operators for $\mathbb{P}$ forms an algebra under composition. We study and link properties and structures on the operator side $\mathbb{O}({\mathbb{P}})$ versus the corresponding family $\mathbb{P}$ of polynomials. For our purposes, we introduce notions such as the PDE-preserving hull and basic sets for a given set $\mathbb{P}$ which, roughly, is the largest, respectively a minimal, collection of polynomials that generate all the PDE-preserving operators for $\mathbb{P}$. We also describe PDE-preserving operators via a kernel theorem. We apply Hilbert's Nullstellensatz.

• Journal of the Korean Statistical Society
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• 제30권2호
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• pp.193-217
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• 2001

Despite of the rich literature in discriminant analysis, this complicated subject remains much to be explored. In this article, we study the theoretical foundation that supports Fisher's linear discriminant analysis (LDA) by setting up the classification problem under the dimension reduction framework as in Li(1991) for introducing sliced inverse regression(SIR). Through the connection between SIR and LDA, our theory helps identify sources of strength and weakness in using CRIMCOORDS(Gnanadesikan 1977) as a graphical tool for displaying group separation patterns. This connection also leads to several ways of generalizing LDA for better exploration and exploitation of nonlinear data patterns.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1494-1501
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• 2008

Recently, the demand of water resources is constantly increasing due to the substantial increase of population, economy, and living standard. However, it is expected that the water resources should undergo serious problems of poor quality of water as well as shortage of water supply in the near future. Additionally, thoughtless groundwater development have caused to dry river and stream. In this study, the effectiveness of dry stream protection plan is evaluated by using 3-D groundwater flow modeling for the study area which is located in Namyangju of Kyoungi Province. Aquifer tests are performed to obtain the input data of the model. To analyze causes of dry stream using modeling results that water balance is analyzed for situations of before and after closing the wells.

• Earthquakes and Structures
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• 제18권6호
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• pp.677-689
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• 2020

A building structural system of moment resisting frame (MRF) with concrete filled steel tubular (CFST) columns and wide flange H beams, is one of the most conveniently constructed structural systems. However, there were few studies on evaluating seismic performance of full-scale CFST columns under high axial compression. In addition, some existing famous design codes propose various limits of width-to-thickness ratio (B/t) for steel tubes of the ductile CFST composite members. This study was intended to investigate the seismic behavior of CFST columns under high axial load compression. Four full-scale square CFST column specimens with a B/t of 42 were carried out that were subjected to horizontal cyclic-reversal loads combined with constantly light, medium and high axial loads and with a linearly varied axial load, respectively. Test results revealed that shear strength and deformation capacity of the columns significantly decreased when the axial compression exceeded 0.35 times the nominal compression strength of a CFST column, P₀. It was obvious that the higher the axial compression, the lower both the shear strength and deformation capacities were, and the earlier and faster the shear strength degradation occurred. It was found as well that higher axial compressions resulted in larger initial lateral stiffness and faster degradation of post-yield lateral stiffness. Meanwhile, the lower axial compressions led to better energy dissipation capacities with larger cumulative energy. Moreover, the study implied that under axial compressions greater than 0.35P₀, the CFST column specimens with B/t limits recommended by AISC 360 (2016), ACI 318 (2014), AIJ (2008) and EC4 (2004) codes do not provide ultimate interstory drift ratio of more than 3% radian, and only the limit in ACI 318 (2014) code satisfies this requirement when axial compression does not exceed 0.35P₀.

• 한국식품영양과학회지
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• 제35권2호
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• pp.150-157
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• 2006

당뇨병은 생체내 당 이용 능력의 이상으로 일어나는 만성 대사성 질환으로서 심혈관계 합병증이 일으키는 대표 증상인 고혈당과 지질대사를 치료하기 위하여 많은 환자들이 민간요법에 의존하고 있다. 이에 본 연구는 홍화씨와 한약재 혼합 추출물이 혈당강하와 지질상태 개선에 대한 효능을 검증하고자 실시하였다. 당뇨는 streptozotocin(45 mg/kg B.W.) 으로 S.D.계 흰쥐에게 근육주사로 유도시킨 다음 주재료로 볶은 홍화씨 50g, 100 g 각각에 부재료로 맥문동, 감초, 상엽, 백복령, 숙지황, 비파엽, 독활, 대추, 산수유, 목단피, 천화분, 오미자를 섞어서 만든 한방 혼합 추출물을 당뇨 유도 쥐에게 체중 kg 당 100 mg, 200 mg의 홍화씨를 섭취할 수 있도록 각각 경구 투여하였다. 당뇨쥐의 고혈당 증상은 100 g의 홍화씨를 넣고 추출한 한약재 흔합추출물의 투여로 정상수준은 아니었지만 $34\%$ 낮아졌다(p<0.0.5). 혈장 내 지질과산화물 함량은 정상군과 당뇨 유도군 간에 유의한 차이는 없었으나, 간 마이크로좀의 지질과산화물 함량은 정상군은 $6.20{\pm}2.25\;nmol/mg$ protein에 비하여 당뇨군은 7.74 nmol/mg protein로 p<0.05수준에서 높았다. 그러나 100 g의 홍화씨를 첨가하여 만든 한약재 흔합추출물 투여했을 때 5.85 nmol/mg protein 수준까지 낮추어 주었다. 혈액과 간 조직 내 중성지방 함량은 역시 100 g의 홍화씨를 첨가하여 만든 한약재 흔합추출물 투여로 p<0.05 수준에서 저하효과가 현저하였다(p<0.05). 그러나 혈액과 간 조직 내 유리지방산, 총콜레스테롤과 인지질함량은 실험 전 군에서 유의적인 차이를 볼 수 없었고, 정상군에 비하여 당뇨군에서 혈장내 HDL-콜레스테롤과 동맥경화지수가 유의적으로 높은 반면에 HDL-콜레스테롤은 낮았으며 홍화씨와 한약재 흔합추출물이 이들 함량 변화에 미치는 효과는 관찰되지 않았다. 이상의 본 실험 결과는 당뇨에 의한 혈당, 지질과산화물 그리고 중성지방 증가는 홍화씨와 한약재 흔합추출물의 투여로 다소 완화되었다. 이러한 결과를 바탕으로 체내 혈당조절에 의한 당뇨병의 예방 및 치유효과가 있는 홍화씨와 같은 천연물질의 기능성 성분에 대하여 향후에 보다 심층 있는 연구를 통하여 건강 기능성 식품 소재로 활용하는 것이 매우 중요할 것으로 여겨진다.