• Journal of Microbiology and Biotechnology
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• 제22권9호
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• pp.1185-1192
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• 2012

This study investigated the hydrocarbonoclastic microbial community present on weathered crude oil and their ability to degrade weathered oil in seawater obtained from the Gulf St. Vincent (SA, Australia). Examination of the native seawater communities capable of utilizing hydrocarbon as the sole carbon source identified a maximum recovery of just $6.6{\times}10^1\;CFU/ml$, with these values dramatically increased in the weathered oil, reaching $4.1{\times}10^4\;CFU/ml$. The weathered oil (dominated by > $C_{30}$ fractions; $750,000{\pm}150,000mg/l$) was subject to an 8 week laboratory-based degradation microcosm study. By day 56, the natural inoculums degraded the soluble hydrocarbons (initial concentrations $3,400{\pm}700mg/l$ and $1,700{\pm}340mg/l$ for the control and seawater, respectively) to below detectable levels, and biodegradation of the residual oil reached 62% ($254,000{\pm}40,000mg/l$) and 66% ($285,000{\pm}45,000mg/l$) in the control and seawater sources, respectively. In addition, the residual oil gas chromatogram profiles changed with the presence of short and intermediate hydrocarbon chains. 16S rDNA DGGE sequence analysis revealed species affiliated with the genera Roseobacter, Alteromonas, Yeosuana aromativorans, and Pseudomonas, renowned oil-degrading organisms previously thought to be associated with the environment where the oil contaminated rather than also being present in the contaminating oil. This study highlights the importance of microbiological techniques for isolation and characterisation, coupled with molecular techniques for identification, in understanding the role and function of native oil communities.

• 한국식품영양과학회지
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• 제37권12호
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• pp.1554-1559
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• 2008

STZ를 이용한 당뇨유발은 독성물질에 의한 췌장 세포의 파괴를 인위적으로 유도시킴으로써 일정하게 고혈당을 유지 시켜주는 방법이다. 장기적인 고혈당은 인슐린의 민감도를 감소시키고 췌장기능을 저하시키며 잠재적으로는 당뇨병의 악화 및 심혈관 합병증을 유도한다(28,29). 이에 본 연구에서는 STZ로 당뇨를 유발한 흰쥐에 AD복합물을 단회 및 반복 투여한 후 혈당변화에 미치는 영향을 조사한 결과 AD복합물의 단회 투여에서 시간별($0{\sim}4$시간)로 혈당변화가 관찰되었다. DC군의 공복혈당은 $437.3{\pm}28mg/dL$에서 3시간 후의 혈당이 $443.3{\pm}28mg/dL$로 거의 변화가 없었던 반면 AD1군은 $414.0{\pm}19mg/dL$에서 $358{\pm}35mg/dL$로 AD2군은 $401.0{\pm}28mg/dL$에서 $351{\pm}16mg/dL$로 혈당이 낮춰졌다. 또한 경구당부하 실험에서는 DC군에 비해 AD복합물 투여군이 포도당 투여 1시간 후의 혈당상승을 억제하고 빠른 속도로 원래의 혈당으로 회복시키는 역할을 하는 것으로 확인되었다. 이러한 결과들이 AD복합물의 장기투여에서도 나타나는지 확인하기 위하여 STZ로 당뇨를 유발시킨 흰쥐에 4주 동안 AD복합물을 투여하고 1주마다 혈당변화를 측정한 결과 DC군은 4주 동안 투여 전(0주) 혈당인 $385{\pm}9mg/dL$를 마지막 주인 4주까지 $365{\pm}6mg/dL$로 꾸준히 비슷하게 유지한 반면, AD1군은 투여 전 혈당인 $349{\pm}9mg/dL$에서 $260{\pm}8mg/dL$로 감소한 것으로 나타났고 AD2군은 투여 전 혈당인 $430{\pm}10mg/dL$에서 $267{\pm}38mg/dL$로 공복 시 혈당저하 효능을 갖는 것으로 나타났다. 또한 AD복합물의 투여는 당뇨로 인한 체중감소를 억제하는 효과가 나타났다. 이러한 결과는 체내의 당대사를 촉진시켜 공복혈당감소와 체중감소억제 효과가 나타난 것으로 사료된다.

• 한국식품영양과학회지
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• 제40권4호
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• pp.565-569
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• 2011

개별인정형 건강기능식품 기능성 원료로 개발한 창녕양파추출액의 표준화를 위해 지표성분으로 quercetin을 설정하였으며, HPLC를 이용하여 지표성분 quercetin의 분석법을 확립하며 그에 따른 유효성 검정을 실시하고자 하였다. 유효성 검정 결과, 본 시험법에서 표준용액의 피크유지시간과 창녕양파추출액의 피크유지시간이 일치하였으며 동일한 spectrum을 나타내어 특이성을 확인하였다. 검량선의 상관계수($R^2$)는 0.9986로 높은 직선성을 보여 분석에 적합함을 알 수 있었으며, 검출한계는 0.2 mg/L, 정량한계는 0.5 mg/L 로 설정되었다. Quercetin의 회수율은 0.05 mg/mL에서는 82.36~95.26%, 0.075 mg/mL는 82.70~98.24%, 0.1 mg/mL은 87.91~95.11%의 범위의 회수율을 보였으며, intra-day에서의 정밀도(RSD)는 0.10~3.28%, inter-day에서는 0.96~5.79%의 정밀도를 나타내어 창녕양파추출액의 지표성분인 quercetin의 분석법은 적합한 시험법임이 검증되었다.

• 문화기술의 융합
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• 제9권6호
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• pp.867-873
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• 2023

본 연구는 감기약의 품질관리를 위한 기초자료서, HPLC를 이용하여 감기약의 4가지 주요 성분인 아세트아미노펜(Acetaminophen), 카페인(Caffeine), 메틸 파라벤(Methly paraben), 프로필 파라벤(Propyl paraben)을 동시 분석하였다. 시료는 4가지 성분을 전처리한 후, 액체크로마토그래피(HPLC)를 사용하여 정량분석 하였다. 감기약의 분석은 상업용 C18 칼럼과 이동상으로 아세토니트릴(Acetonitrile) 과 증류수(H₂O)을 사용하였으며, 아이소그라틱 기법(Isocratic Elution)을 사용하였다. 검출기는 PDA 및 UV detector를 사용하였으며, 유속은 1.0mL/min, 주입부피는 10uL, 칼럼오븐의 온도는 35℃, 파장은 270nm에서 수행하였다. 실험 결과 Resolution의 값이 각각 4.983, 1.596, 5.519, 1.678으로 Rs >1.5 이상으로 나타나 분리능이 우수하고 Symmetry factor 값은 1.056, 1.069, 1.032, 1.133으로 안정적인 대칭을 갖는 것을 알 수 있었다. 모든 표준성분의 검량선 값은 R² > 0.9995 ~ 0.9999로 나타나 우수한 직선성을 나타내었다. 또한 검출한계(Llimit of detection) 와 정량한계(Limit of quantification)는 각각 0.0118 ~ 1.5973mg/mL 및 0.0353 ~ 4.7919㎍/mL, 회수율은 79.6% ~ 120.5%로 안정적인 값을 얻었다. 본 연구 결과는 실험적으로 입증한 감기약 성분의 동시 분석법에 의한 품질평가가 효율적임을 보여주었다

• Communications for Statistical Applications and Methods
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• 제22권6호
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• pp.543-556
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• 2015

We present a survey of contributions that defined the nature and extent of robust statistics for the last 50 years. From the pioneering work of Tukey, Huber, and Hampel that focused on robust location parameter estimation, we presented various generalizations of these estimation procedures that cover a wide variety of models and data analysis methods. Among these extensions, we present linear models, clustered and dependent observations, times series data, binary and discrete data, models for spatial data, nonparametric methods, and forward search methods for outliers. We also present the current interest in robust statistics and conclude with suggestions on the possible future direction of this area for statistical science.

• Journal of Mechanical Science and Technology
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• 제14권9호
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• pp.978-984
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• 2000

The aim of this study is to investigate the ductile fracture behaviour under Mode I loading using SA533B pressure vessel steel. Experiments consist of the Round Notch Bar Test (RNB), Single Edge Crack Bending Test (SECB), and V-Notch Bar Test (VNB). Results from the RNB test were used to tune the damage modelling constant. The other tests were performed to acquire the J-resistance curves and to confirm the damage constants. Microstructural observation includes the measurement of crack profile to obtain the roughness parameter. Finally, simulation using Rousellier Ductile Damage Theory (RDDT) was carried out with 4-node quadrilateral element ($L_c=0.25\;mm$). For the crack advance, the failed element removal technique was adopted with a ${\beta}$ criterion. In conclusion, the predicted simulation using RDDT showed a good agreement with the experimental results. A trial using a roughness parameter was made for a new evaluation of J-resistance curve, which is more conservative than the conventional one.

• Computers and Concrete
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• 제17권5호
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• pp.597-612
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• 2016

The present work focuses on the use of coconut fiber in self compacting concrete. Self-Compacting Concrete (SCC) is a highly flowable, stable concrete which flows readily into place, filling formwork without any consolidation and without undergoing any significant segregation. Use of fibers in SCC bridge the cracks and enhance the performance of concrete by not allowing cracks to propagate. They contribute to an increased energy absorption compared to plain concrete. Coconut fiber has the highest toughness among all natural fibers. It is known that structures in the seismic prone areas are always under the influence of cyclic loading. To justify the importance of strengthening SCC beams with coir fiber, the present work has been undertaken. A comparison is made between cyclic and static loading of coconut fiber reinforced self compacting concrete (FRSCC) members. Using the test data obtained from the experiment, hysteresis loops were drawn and comparison of envelope curve, energy dissipation, stiffness degradation were made and important conclusions were draw to justify the use of coconut fiber in SCC.

• Geomechanics and Engineering
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• 제13권2호
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• pp.217-235
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• 2017

The stability prediction of shallow buried tunnels is one of the most difficult tasks in civil engineering. The aim of this work is to predict the state of collapse in shallow tunnel in layered soils by employing non-associated flow rule and nonlinear failure criterion within the framework of upper bound theorem. Particular emphasis is first given to consider the effects of dilation on the collapse mechanism of shallow tunnel. Furthermore, the seepage forces and surface settlement are considered to analyze the influence of different dilation coefficients on the collapse shape. Two different curve functions which describe two different soil layers are obtained by virtual work equations under the variational principle. The distinct characteristics of falling blocks up and down the water level are discussed in the present work. According to the numerical results, the potential collapse range decreases with the increase of the dilation coefficient. In layered soils, both of the single layer's dilation coefficient and two layers' dilation coefficients increase, the range of the potential collapse block reduces.

• 충청수학회지
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• 제29권2호
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• pp.267-281
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• 2016

In this paper, we consider multi-degree reduction of $B{\acute{e}}zier$ curves with continuity of any (r, s) order with respect to $L_2$ norm. With help of matrix theory about generalized inverses we can use Lagrange multipliers to obtain the degree reduction matrix in a very simple form as well as the degree reduced control points. Also error analysis comparing with the least squares degree reduction without constraints is given. The advantage of our method is that the relationship between the optimal multi-degree reductions with and without constraints of continuity can be derived explicitly.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.548-551
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• 1999

The cure characteristics of metal particle filled DGEBA/MDA/SN/ zeolite epoxy resin composite system for EMI shielding were investigated by dynamic DSC run method and FT-lR spectroscopy. As the heating rate increased, the peak temperature on dynamic DSC curve increased because of the rapid cure reaction. From the straight line of the Kissinger plot, the curing reaction activation energy and pre-exponential factor could be obtained. As the post-curing time at 15$0^{\circ}C$ increased, the glass increased the glass transition temperature or the thermal stability increased. When the post curing time is too long, the system filled with metallic Al particle can be thermally oxidized by the catalytic reaction of metal filler and the thermal stability of the composite for the EMI shielding application may be decreased.