• 분석과학
• /
• 제26권5호
• /
• pp.340-351
• /
• 2013

The chemical element and structural characterization of different types of cements and its brick stones are been investigated under forensic aspects using X-ray florescence (XRF) and X-ray diffraction (XRD) spectrometer. The XRF provides rapid compositional data for controlling almost all stages of raw materials, clinker and cement. The decisive advantage of XRD methods is based on the unique character of the diffraction patterns of crystalline substances, the ability to distinguish between elements and their oxides, and the possibility to identify chemical compounds, polymeric forms, and mixed crystals by non-destructive examination. Therefore, combination of these examinations is useful and able to apply for the forensic analysis in comparison of cements and brick stones. There are more study remained to determine the viability of method for forensic analysis of brick stones and the limits of the discrimination that can be achieved.

• Advances in materials Research
• /
• 제9권4호
• /
• pp.251-263
• /
• 2020

α-mangostin imprinted polymers have been synthesized by a non-covalent imprinting approach with α-mangostin as a template molecule. The α-mangostin molecularly imprinted polymers (MIPs) prepared by radical polymerization using methacrylic acid, ethlylene glycol dimethacrylate, benzoyl peroxide, and acetonitrile, as a monomer, crosslinker, initiator, and porogen, respectively. The template was removed by using methanol:acetic acid 90:10 (v/v). The physical characteristics of the polymers were investigated by Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The rebinding studies were carried out by batch methods. The results exhibited that the MIPs was able to adsorb the α-mangostin at pH 2 and the contact time of 180 min. The kinetic adsorption data of α-mangostin performed the pseudo-second order model and followed the Langmuir isotherm model with the adsorption capacity of 16.19 mg·g-1. MIPs applied as a sorbent material in solid-phase extraction, namely molecularly imprinted solid-phase extraction (MISPE) and it shows the ability for enrichment and clean-up of α-mangostin from the complex matrix in medicinal herbal product and crude extract of mangosteen (Garcinia mangostana L.) pericarp. Both samples, respectively, which were spiked with α-mangostin gives recovery more than 90% after through by MISPE in all concentration ranges.

• 분석과학
• /
• 제19권1호
• /
• pp.9-17
• /
• 2006

생체 물질의 농도, 두께 및 특정 생체 물질의 분석을 위한 반응 속도론적 자료를 검출하는 능력 그리고 antigen/antibody, ligand/receptor, protein/protein 및 DNA/DNA 상호작용을 포함하는 다양한 생체물질간의 상호작용에 대한 분석에 적용되고, 자연 환경중 오염물질의 분석 등 다양하게 적용되는 표면 플라즈몬 공명 센서를 제작하였다. 또한 표면 플라즈몬 공명 센서를 제어하고 검출기로부터의 데이타(data)를 personal computer로 받아들이기 위해 data acquisition board를 이용하여 LabVIEW program을 만들었다.

• Advances in nano research
• /
• 제16권3호
• /
• pp.251-263
• /
• 2024

This article investigates the free vibration behavior of carbon nanotube reinforced composite (CNTRC) beams embedded using variational analytical methods and artificial neural networks (ANN). The material properties of layered functionally graded CNTRC (FG-CNTRC) beams are estimated using nonlocal parameters modified power-law with different types of CNT distributions through the thickness direction of the beam. Adopting Eringen's nonlocal elasticity theory to capture the small size effects, the nonlocal governing equations are derived and solved using the analytical method. And also, the problem was analyzed using the ANN method. The architecture of the proposed ANN model is 3-9-1. In the experiments, we used 112 different data to predict the natural frequency using ANN. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion as well as the boundary conditions of the beam are derived using Hamilton's principle. The classical beam theory is used to formulate a governing equation for predicting the free vibration of laminated CNTRC beams. According to the experimental results, the prediction ability of the ANN model is very good and the natural frequency can be predicted in ANN without attempting any experiments.

• 한국산학기술학회논문지
• /
• 제22권4호
• /
• pp.83-89
• /
• 2021

본 연구는 학습정서, 학습스타일이 예비유아교사의 학습공동체함여 역량에 미치는 영향을 살펴보았다. 이를 위하여 유아교육관련 학과에 재학중인 학생 234명을 대상으로 설문조사를 실시하였다. 조사결과 수집된 변인은 예비유아교의 학습공동체 참여역량, 예비유아교사가 학업수행할 때 경험하는 정서(긍정정서, 부정정서), 그리고, 학습스타일 (학습태도, 학습동기, 교육내용, 교수방법)로 나타났다. 연구 결과, 먼저 예비교사의 학습공동체참여역량은 예비교사들의 학습스타일 중 분석적 학습태도, 학습동기, 교수방법에 있어 토론 및 토론유형을 선호하는 정도, 실험 및 실습 유형을 선호하는 정도와 유의한 상관을 나타내었으며, 학습정서의 하위범주인 긍정정서와 부정정서와도 유의한 상관이 있었다. 회귀분석결과, 예비교사들의 학습정서의 하위범주인 부정정서, 학습스타일 중 학습동기, 교수방법유형 중 실험 및 실습유형을 선호하는 정도, 분석적인 학습태도, 그리고 교육내용 중 전공학문을 지향하며 그 중요성에 가치를 두는 정도는 예비교사의 학습공동체참여역량에 유의미한 것으로 나타났다. 본 연구결과는 예비교사를 양성하는 교육현장이 단순히 전공관련 지식을 전달하는 데 그치는 것이 아니라, 학습자들로 하여금 학습공동체참여역량을 갖출 수 있는 경험을 제공하기 위한 노력을 할 수 있어야 함을 시사하고 있다.

• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 2003년도 International Symposium on Clean Environment
• /
• pp.135-138
• /
• 2003

Based on solid phase extraction, gas chromatography and mass spectrometry procedure for determining phenol and its derivatives in natural water was presented. In solid phase extraction, three types of techniques using solid phase adsorption material were treated with acid and salt, and converted second portion of acetyl derivatives. Under the these condition, extraction efficiency and detection ability dependent on extraction methods were discussed. Obtained results using optimized solid phase extraction techniques showed more convenience, simplifier and lower cost than the conventional analytical methods with holding wide dynamic range and lower detection limits.

• 분석과학
• /
• 제14권3호
• /
• pp.286-289
• /
• 2001

The effect of pH and the substrate concentration on the sensing ability of the chicken peroxidase enzyme electrode was examined quanititatively. Using the new Michaelis-Menten equation, to which pH concept was introduced, enabled to calculate all kinds of dissociation constant related to chicken peroxidase and subsequently to determine the optimum pH of the sensor.

• 분석과학
• /
• 제8권4호
• /
• pp.529-534
• /
• 1995

The metal ion selective resins were prepared by surface template polymerization using monooleyl phosphoric acid (1), oleyl methyl phosphoric acid (2) or oleyl ethyl phosphoric acid (3) as an amphiphilic host surfactant. The $Cu^{2+}$-imprinted resins prepared in the presence of $Cu^{2+}$ adsorbed $Cu^{2+}$ much more effectively than did their reference resins. On the other hand, the $Cu^{2+}$-imprinted resins showed much less binding ability to $Zn^{2+}$. The template-dependent selectivity should be ascribed to a favorable placement of the surface-anchored metallophilic groups for multidentate coordination to specific metal ion.

• Smart Structures and Systems
• /
• 제21권3호
• /
• pp.335-347
• /
• 2018

The fast-growing number of mobile and wearable applications has driven several innovations in small-scale electret-based energy harvesting due to the compatibility with standard microfabrication processes and the ability to generate electrical energy from ambient vibrations. However, the current modeling methods used to design these small scale transducers or microgenerators are applicable only for constant-speed rotations and small sinusoidal translations, while in practice, large amplitude sinusoidal vibrations can happen. Therefore, in this paper, we formulate an analytical model for electret-based microgenerators under general sinusoidal excitations. The proposed model is validated using finite element modeling combined with numerical simulation approaches presented in the literature. The new model demonstrates a good agreement in estimating both the output voltage and power of the microgenerator. This new model provides useful insights into the microgenerator operating mechanism and design trade-offs, and therefore, can be utilized in the design and performance optimization of these small structures.

• Steel and Composite Structures
• /
• 제33권2호
• /
• pp.163-180
• /
• 2019

A semi analytical method is employed to analyze free vibration characteristics of uniform and stepped functionally graded circular cylindrical shells under complex boundary conditions. The analytical model is established based on multi-segment partitioning strategy and first-order shear deformation theory. The displacement functions are handled by unified Jacobi polynomials and Fourier series. In order to obtain continuous conditions and satisfy complex boundary conditions, the penalty method about spring technique is adopted. The solutions about free vibration behavior of functionally graded circular cylindrical shells were obtained by approach of Rayleigh-Ritz. To confirm the dependability and validity of present approach, numerical verifications and convergence studies are conducted on functionally graded cylindrical shells under various influencing factors such as boundaries, spring parameters et al. The present method apparently has rapid convergence ability and excellent stability, and the results of the paper are closely agreed with those obtained by FEM and published literatures.