• 한국가스학회지
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• 제22권5호
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• pp.72-78
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• 2018

최근 가스안전기기의 동향은 무선 기술의 발전과 수요자의 요구에 따라 무선 가스안전기기에 대한 개발과 연구가 활발히 이루어지고 있다. 무선의 신뢰성에 대한 논란이 제기되고 있지만 무선의 편리성이란 강점으로 가스안전기기에 도입이 확대되고 있으므로 이러한 기기의 안전성과 신뢰성을 검증할 수 있는 합리적인 성능평가 방안이 필요하다. 본 논문은 무선 가스안전기기에 대한 안전성과 신뢰성을 확인하여 기기가 원활하게 확대 보급될 수 있도록 성능평가 장치 설계 제작과 성능평가 방안 제시를 목적으로 한다. 이를 위하여 국내 외 무선 가스안전기기 관련제도를 조사하여 신뢰성과 안전성을 확인하는 기능과 방법을 검토하고 주요기능에 대해 시험평가가 가능한 장치를 제작하며 무선가스안전기기의 신뢰성과 안전성 요구조건을 만족시키는 주요 성능평가 항목(안)과 시험방안을 제시한다.

• 한국미생물·생명공학회지
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• 제48권1호
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• pp.12-23
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• 2020

Edible films containing antimicrobial agents can be used as safe alternatives to preserve food products. Essential oils are well-recognized antimicrobials. However, their low water solubility, volatility and high sensitivity to oxygen and light limit their application in food preservation. These limitations could be overcome by embedding these essential oils in complexed product matrices exploiting the encapsulation efficiency of β-cyclodextrin. This study focused on the maximization of β-cyclodextrin production using cyclodextrin glucanotransferase (CGTase) and the evaluation of its encapsulation efficacy to fabricate edible antimicrobial films. Response surface methodology (RSM) was used to optimize CGTase production by Brevibacillus brevis AMI-2 isolated from mangrove sediments. This enzyme was partially purified using a starch adsorption method and entrapped in calcium alginate. Cyclodextrin produced by the immobilized enzyme was then confirmed using high performance thin layer chromatography, and its encapsulation efficiency was investigated. The clove oil/β-cyclodextrin inclusion complexes were prepared using the coprecipitation method, and incorporated into chitosan films, and subjected to antimicrobial testing. Results revealed that β-cyclodextrin was produced as a major product of the enzymatic reaction. In addition, the incorporation of clove oil/β-cyclodextrin inclusion complexes significantly increased the antimicrobial activity of chitosan films against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella Typhimurium, Escherichia coli, and Candida albicans. In conclusion, B. brevis AMI-2 is a promising source for CGTase to synthesize β-cyclodextrin with considerable encapsulation efficiency. Further, the obtained results suggest that chitosan films containing clove oils encapsulated in β-cyclodextrin could serve as edible antimicrobial food-packaging materials to combat microbial contamination.

• Bioinformatics and Biosystems
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• 제1권1호
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• pp.67-72
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• 2006

The aim of this paper is to discuss the effect of missing values in detecting differentially expressed genes in a cDNA microarray experiment in the context of a one sample problem. We conducted a cDNA micro array experiment to detect differentially expressed genes for the metastasis of colorectal cancer based on twenty patients who underwent liver resection due to liver metastasis from colorectal cancer. Total RNAs from metastatic liver tumor and adjacent normal liver tissue from a single patient were labeled with cy5 and cy3, respectively, and competitively hybridized to a cDNA microarray with 7775 human genes. We used $M=log_2(R/G)$ for the signal evaluation, where Rand G denoted the fluorescent intensities of Cy5 and Cy3 dyes, respectively. The statistical problem comprises a one sample test of testing E(M)=0 for each gene and involves multiple tests. The twenty cDNA microarray data would comprise a matrix of dimension 7775 by 20, if there were no missing values. However, missing values occur for various reasons. For each gene, the no missing proportion (NMP) was defined to be the proportion of non-missing values out of twenty. In detecting differentially expressed (DE) genes, we used the genes whose NMP is greater than or equal to 0.4 and then sequentially increased NMP by 0.1 for investigating its effect on the detection of DE genes. For each fixed NMP, we imputed the missing values with K-nearest neighbor method (K=10) and applied the nonparametric t-test of Dudoit et al. (2002), SAM by Tusher et al. (2001) and empirical Bayes procedure by $L\ddot{o}nnstedt$ and Speed (2002) to find out the effect of missing values in the final outcome. These three procedures yielded substantially agreeable result in detecting DE genes. Of these three procedures we used SAM for exploring the acceptable NMP level. The result showed that the optimum no missing proportion (NMP) found in this data set turned out to be 80%. It is more desirable to find the optimum level of NMP for each data set by applying the method described in this note, when the plot of (NMP, Number of overlapping genes) shows a turning point.

• 한국토양비료학회지
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• 제34권4호
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• pp.273-277
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• 2001

실험실에서의 기존의 토양분석방법은 많은 시약을 사용하고 분석시간이 많이 걸린다. 본 연구는 근적외 분광분석기를 이용하여 토양의 여러 가지 이화학성분에 대한 측정결과를 검토하였다. 토양시료를 몰탈로 갈아서 토양입자를 0.2mm의 체를 통과시킨 140점의 토양시료를 85점은 근적외 분광분석기(InfraAlyzer 500, Bran & Luebbe Co.)로 표준곡선을 작성하고 나머지 55점의 토양시료는 표준곡선을 이용하여 토양의 이화학성중에서 토양 pH, CEC, 치환성 Ca, Mg, K 및 유효규산, 휴믹산 및 전기전도도(EC)를 추정하였다. 표준곡선은 부분최소자승법을 이용하여 작성하였다. 토양시료를 곱게 분쇄하면 근적외선의 고른 확산반사를 얻을 수 있어서, 근적외 분광분석기를 이용하여 여러 기지 토양의 화학성을 수초내에 추정할 수 있어 토양검정에 이용할 수 있을 것으로 생각된다.

• Smart Structures and Systems
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• 제21권1호
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• pp.53-64
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• 2018

Nondestructive testing methods are required to assess the condition of civil structures and formulate their maintenance programs. Axial force identification is required for several structural members of truss bridges, pipe racks, and space roof trusses. An accurate evaluation of in situ axial forces supports the safety assessment of the entire truss. A considerable redistribution of internal forces may indicate structural damage. In this paper, a novel compressive force identification method for prismatic members implemented using static deflections is applied to steel beams. The procedure uses the Euler-Bernoulli beam model and estimates the compressive load by using the measured displacement along the beam's length. Knowledge of flexural rigidity of the member under investigation is required. In this study, the deflected shape of a compressed steel beam is subjected to an additional vertical load that was short-term measured in several laboratory tests by using fiber Bragg grating-differential settlement measurement (FBG-DSM) sensors at specific cross sections along the beam's length. The accuracy of midspan deflections offered by the FBG-DSM sensors provided excellent force estimations. Compressive load detection accuracy can be improved if substantial second-order effects are induced in the tests. In conclusion, the proposed method can be successfully applied to steel beams with low slenderness under real conditions.

• 한국철도학회논문집
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• 제11권1호
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• pp.54-60
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• 2008

다층 탄성모델에 근거한 철도노반 설계는 열차의 반복 윤하중에 의한 궤도 하부 구조의 거동을 반영하는 응력 의존적인 회복탄성계수$(E_R)$가 각 층의 중요한 입력물성치가 된다. 그러나 반복하중을 가하는 기존의 회복탄성계수 시험법은 비용이 고가이고 시험장비와 숙련도에 따라 결과의 일관성이 떨어지는 단점이 있어 실질적인 적용에 어려움이이었다. 본 연구에서는 이를 극복하기 위해 동적물성치를 이용한 대체 회복탄성계수 시험법을 적용하여 철도노반의 회복탄성계수를 결정하였다. 강화노반에 주로 사용되는 쇄석의 회복탄성계수는 측정된 동적물성치와 열차 운행 중 경험하는 강화노반의 응력을 고려하여 결정되었고, 체적응력과 축차응력의 거듭제곱 형태로 예측모델을 나타내었다. 쇄석의 회복탄성계수는 체적응력이 증가함에 따라 전체적으로 증가하는 경향을 보였고 축차응력이 증감함에 따라 감소하였다. 상 하부노반의 주재료인 SM계열 토사 재료에 대하여 회복탄성계수를 평가하였고, 축차응력만을 이용한 거듭제곱 형태의 예측모델과 상관성이 매우 높게 나타났다.

• Structural Monitoring and Maintenance
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• 제2권1호
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• pp.19-34
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• 2015

One of the main causes of a limited use of nondestructive evaluation (NDE) technologies in bridge deck assessment is the speed of data collection and analysis. The paper describes development and implementation of the RABIT (Robotics Assisted Bridge Inspection Tool) for data collection using multiple NDE technologies. The system is designed to characterize three most common deterioration types in concrete bridge decks: rebar corrosion, delamination, and concrete degradation. It implements four NDE technologies: electrical resistivity (ER), impact echo (IE), ground-penetrating radar (GPR), and ultrasonic surface waves (USW) method. The technologies are used in a complementary way to enhance the interpretation. In addition, the system utilizes advanced vision to complement traditional visual inspection. Finally, the RABIT collects data at a significantly higher speed than it is done using traditional NDE equipment. The robotic system is complemented by an advanced data interpretation. The associated platform for the enhanced interpretation of condition assessment in concrete bridge decks utilizes data integration, fusion, and deterioration and defect visualization. This paper concentrates on the validation and field implementation of two NDE technologies. The first one is IE used in the delamination detection and characterization, while the second one is the USW method used in the assessment of concrete quality. The validation of performance of the two methods was conducted on a 9 m long and 3.6 m wide fabricated bridge structure with numerous artificial defects embedded in the deck.

• Advances in Traditional Medicine
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• 제7권1호
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• pp.51-64
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• 2007

Mucus is an aqueous gel complex with a constitution of about 95% water, high molecular weight glycoprotein (mucin), lipid, salts etc. Mucus appears to represent a significant barrier to the absorption of some compounds. Natural mucoadhesive agent was isolated and purified from the aqueous extract of the seeds of prosopis pallida (PP). Formulated tablet with the isolated material by wet granulation method. Some natural edible substances are in consideration for candidates as mucoadhesive agents to claim more effective controlled drug delivery as an alternative to the currently used synthetic mucoadhesive polymers. Subjected the materials obtained from natural source i.e. PP and standard synthetic substance, sodium carboxymethyl cellulose for evaluation of mucoadhesive property by various in vitro and in vivo methods. Through standard dissolution test and a model developed with rabbit, evaluated in vitro controlled release and bioadhesive property of theophylline formulation. Mucoadhesive agent obtained from PP showed good mucoadhesive potential in the demonstrated in vitro and in viνo models. The results suggest that the mucoadhesive agent showed controlled release properties by their application, substantially. In order to assess the gastrointestinal transit time in vivo, a radio opaque X-ray study performed in healthy rabbit testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of theophylline determined by the HPLC method and those allowed correlations to the in vitro mucoadhesive study results. Better correlation found between the results in different models. PP may acts as a better natural mucoadhesive agent in the extended drug delivery system.

• 한국수소및신에너지학회논문집
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• 제24권2호
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• pp.128-135
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• 2013

The nuclear fuel cycle plant is composed of various subsystems such as a fuel storage and delivery system (SDS), a tokamak exhaust processing system, a hydrogen isotope separation system, and a tritium plant analytical system. Korea is sharing in the construction of the International Thermonuclear Experimental Reactor (ITER) fuel cycle plant with the EU, Japan, and the US, and is responsible for the development and supply of the SDS. Hydrogen isotopes are the main fuel for nuclear fusion reactors. Metal hydrides offer a safe and convenient method for hydrogen isotope storage. The storage of hydrogen isotopes is carried out by absorption and desorption in a metal hydride bed. These reactions require heat removal and supply respectively. Accordingly, the rapid storage and delivery of hydrogen isotopes are enabled by a rapid cooling and heating of the metal hydride bed. In this study, we designed and manufactured a vertical-type hydrogen isotope storage bed, which is used to enhance the cooling performance. We present the experimental details of the cooling performances of the bed using various cooling parameters. We also present the modeling results to estimate the heat transport phenomena. We compared the cooling performance of the bed by testing different cooling modes, such as an isolation mode, a natural convection mode, and an outer jacket helium circulation mode. We found that helium circulation mode is the most effective which was confirmed in our model calculations. Thus we can expect a more efficient bed design by employing a forced helium circulation method for new beds.

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.449-459
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• 2017

High-rise buildings are generally sensitive to strong winds. The evaluation of wind loads for the structural design, structural health monitoring (SHM), and vibration control of high-rise buildings is of primary importance. Nevertheless, it is difficult or even infeasible to measure the wind loads on an existing building directly. In this regard, a new inverse method for evaluating wind loads on high-rise buildings is developed in this study based on a discrete-time Kalman filter. The unknown structural responses are identified in conjunction with the wind loads on the basis of limited structural response measurements. The algorithm is applicable for estimating wind loads using different types of wind-induced response. The performance of the method is comprehensively investigated based on wind tunnel testing results of two high-rise buildings with typical external shapes. The stability of the proposed algorithm is evaluated. Furthermore, the effects of crucial factors such as cross-section shapes of building, the wind-induced response type, errors of structural modal parameters, covariance matrix of noise, noise levels in the response measurements and number of vibration modes on the identification accuracy are examined through a detailed parametric study. The research outputs of the proposed study will provide valuable information to enhance our understanding of the effects of wind on high-rise buildings and improve codes of practice.