• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.255-262
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• 2008

Methyl jasmonate (MJ) and yeast extract (YE) induce protein expression and benzophenanthridine alkaloid accumulation in Eschscholtzia californica suspension cell cultures. One hundred ${\mu}M$ MJ primarily induced dihydrosanguinarine $(509.0{\pm}7.4mg/l)$ ; 0.2g/l YE induced sanguinarine $(146.8{\pm}3.8mg/l)$ and an unknown compound. These results occur because dihydrobenzophenanthridine oxidase (DHBO) is induced by YE and not by MJ. YE and chitin (CHI) had similar effects on sanguinarine production and DHBO expression. Differential induction of secondary metabolites was shown in E. californica suspension cultures and the expression of proteins confirmed the metabolite results. Furthermore, treatment by various oligosaccharides helped us to understand the elicitation effect of YE in signal transduction pathways.

• Animal cells and systems
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• 제13권4호
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• pp.363-370
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• 2009

Since vitamin $D_3$ is an important regulator of osteoblastic differentiation, a presently-established vitamin $D_3$-entrapped calcium phosphate film (VCPF) was evaluated for hard tissue engineering. The entrapped vitamin $D_3$ more rapidly induced bone nodule formation. To characterize the cellular events leading to regulations including faster differentiation, signal transduction pathways were investigated in osteoblastic MG63 cells at a molecular level. Major signaling pathways for MG63 cell proliferation including phosphatidylinositol-3-kinase, extracellular signal-regulated kinase, c-Jun N-terminal kinase and focal adhesion kinase pathways were markedly down-regulated when cells were cultured on calcium phosphate film (CPF) and VCPF. This agreed with our earlier observations of the immediate delay in proliferation of MG63 cells upon culture on CPF and VCPF. On the other hand, the p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase A (PKA) pathways were significantly up-regulated on both CPF and VCPF. CPF alone could simulate differential behaviors of MG63 cells even in the absence of osteogenic stimulation and entrapment of vitamin $D_3$ within CPF further amplified the signal pathways, resulting in continued promotion of MG63 cell differentiation. Interplay of p38 MAPK and PKA signaling pathways likely is a significant event for the promotion of differentiation and mineralization of MG63 cells.

• 센서학회지
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• 제6권1호
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• pp.35-42
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• 1997

전기적 제한 방출 시스템을 이용한 페록사이드 측정용 광바이오센서가 개발되었다. HPA를 포함한 PEOx와 PMAA의 고분자 복합체는 전류를 가하게 되면 붕괴되면서, HPA를 방출한다. 고분자 복합체의 붕괴 속도 및 방출되는 HPA의 양은 가해지는 전류의 세기에 비례했다. 페록사이드는 HPA와 페록시다아제효소에 의해 반응되어 형광 물질인 DBDA가 생성되었다. Xenon램프를 이용하여 DBDA를 여기시키고 발생되는 형광을 광섬유와 광다이오드어레이로 측정하였다. 측정된 DBDA의 형광의 변화는 페록사이드의 농도에 비례하였다. 페록시다아제 효소는 Ca-alginate를 이용하여 반응기내벽에 고정화시켰다. 개발된 광바이오센서는 페록사이드 0.025mM - 1.0mM 농도의 측정 범위를 가지며, 페록사이드의 단계 변화에 대한 반복성 있는 센서신호가 조사되었다. 효소 반응과 물질전달현상을 통하여 센서의 수학적 모델을 구성하였으며, 제안된 모델은 실험 결과와 잘 일치함을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3367-3371
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• 2011

An easy and convenient synthetic route to (S)-2-hydroxy-2'-(3-phenyluryl-benzyl)-1,1'-binaphthyl-3-carboxaldehyde (1), capable of recognizing tryptophan by fluorescence has been developed. The binol carboxaldehyde 1 exhibited a high selectivity to L-tryptophan over other examined L-${\alpha}$-amino acids such as alanine, phenylalanine, glutamine, arginine, lysine, serine, threonine, aspartat, valine, histidine and cysteine, with a fluorescence "turn-on" signal. In addition, 1 displayed chiral discrimination with good enantioselectivity toward L-tryptophan over D-tryptophan through different fluorescence enhancement factors.

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.198-204
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• 1994

Chemical shifts in aqueous sodium dodecylsulfate(SDS) micellar solution solublizing phenol, catechol, resorcinol, hydroquinone have been measured to investigate solubilization properties. Proton nuclear magnetic resonance frequencies of solubilizates as well as those of the ${\alpha}$-methylene, middle methylene and terminal methyl of SDS shift linearly as a function of solubilizate concentration. From the plots of observed chemical shift (v) vs solubilizate concentration, slope (a) and solubilizate free chemical shift ($v_0$) are obtained. They are very informative to solubilization site of the systems. Catechol and phenol solubilized SDS and catechol solubilized dodecylpyridinium chloride(DPC), dodecyltrimethylammonium bromide(DTAB) systems are studied using the same method to compare head group effect and middle methylene proton signal splitting. It is proposed that phenol and catechol are inserted into micellar interior and the number of methylenes assigned to the higher field peaks is 5.0${\pm}$0.5.

• 제어로봇시스템학회논문지
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• 제6권12호
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• pp.1113-1119
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• 2000

To operate a process plant safely and economically, process monitoring is very important. Process monitoring is the task to identify the state of the system from sensor data. Process monitoring includes data acquisition, regulatory control, data reconciliation, fault detection, etc. This research focuses on the data recon-ciliation using scale-space filtering and fault detection using functional-link associative neural networks. Scale-space filtering is a multi-resolution signal analysis method. Scale-space filtering can extract highest frequency factors(noise) effectively. But scale-space filtering has too large calculation costs and end effect problems. This research reduces the calculation cost of scale-space filtering by applying the minimum limit to the gaussian kernel. And the end-effect that occurs at the end of the signal of the scale-space filtering is overcome by using extrapolation related with the clustering change detection method. Nonlinear principal component analysis methods using neural network have been reviewed and the separately expanded functional-link associative neural network is proposed for chemical process monitoring. The separately expanded functional-link associative neural network has better learning capabilities, generalization abilities and short learning time than the exiting-neural networks. Separately expanded functional-link associative neural network can express a statistical model similar to real process by expanding the input data separately. Combining the proposed methods-modified scale-space filtering and fault detection method using the separately expanded functional-link associative neural network-a process monitoring system is proposed in this research. the usefulness of the proposed method is proven by its application a boiler water supply unit.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.131-131
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• 2003

The advent of photonic technologies in the field of communications and data transmission has been heavily increasing the demand in integrated optical (IO) circuits capable of accomplishing not only simple tasks like signal, but also more sophisticated functions like all-optical signal routing or active multiplexing/demultiplexing. In the last decade, sol-gel technology has been widely used to prepare optical materials. Sol-gel processes show many promises for the development of low-loss, high-performance glass integrated optical circuits. However, crack formation is likely to occur during heat treatment in thick gel films. In order to overcome the critical thickness limitation, the organic-modified silicate has been widely used. In this case coating matrices have been prepared from the organo-silanes of T structures, acidic catalyst and the as-prepared gel films have been heat-treated below 200$^{\circ}C$ to avoid the crack formation and the degradation of organic components. However, the films prepared in the acidic condition and the low heat temperature make the films contain high OH groups which is the major optical loss function. In this work, C$\sub$6/H$\sub$5/SiO$\sub$1.5/ films were prepared on silicon substrate by sol-gel method using base catalyst in a PTMS/NH$_4$OH/H$_2$O/C$_2$H$\sub$5/OH system. The sol showed spinable viscosity at 50 wt% of solid content, and neglectable viscosity change with time. The films were crack-free and transparent after curing at 450 $^{\circ}C$, and highly condensed to minimize OH content in C$\sub$6/H$\sub$5/SiO$\sub$1.5/ networks. The effects of heat treatment of the films are characterized on the critical thickness, the chemical composition and the refractive indices by means of SEM, FT-IR, TGA, prism coupler, respectively.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.118-124
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• 2024

신경망은 심전도 신호, 망막 영상, 지진파 등 잡음이 포함된 자료의 전처리 작업에 활용되고 있다. 그러나, 잡음의 전처리는 전산시간 증가, 원본 신호의 왜곡등의 문제점을 내포하고 있다. 본 연구에서는 잡음의 전처리 없이 측정 자료를 분석할 수 있는 신경망 구조를 연구하였다. 신경망의 학습 자료로써 잡음이 포함된 DNA 용액의 동역학적 거동을 선정하여, 해당 자료로부터 DNA 용액의 조성비를 예측하고자 하였다. DNA의 동역학 자료에 인위적으로 백색 잡음을 추가하여, 신경망의 예측에 대한 잡음의 영향을 알아보았다. 결과적으로, 잡음의 전처리 없이 O(1)의 신호 대 잡음비 자료로부터 O(0.01)의 오차로 용액의 조성비를 예측할 수 있었다. 이러한 연구 결과는 측정 잡음에 민감하게 영향 받을 수 있는 극미량의 유전병 또는 암세포와 관련된 DNA를 분석을 위한 핵심 인공지능 기술로 활용할 수 있다.

• Elastomers and Composites
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• 제59권2호
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• pp.73-81
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• 2024

In the field of electronic components, the potting material, which is a part of the electronic circuit package, plays a significant role in protecting circuits from the external environment and reducing signal interference among electronic devices during operation. This significantly affects the reliability of the components. Therefore, the accurate prediction and assessment of the lifespan of a material are of paramount importance in the electronics industry. We conducted an accelerated thermal aging evaluation using the Arrhenius technique on elastic potting material developed in-house, focusing on its insulation, waterproofing, and contraction properties. Through a comprehensive analysis of these properties and their interrelations, we confirmed the primary factors influencing molding material failure, as increased hardness is related to aggregation, adhesion, and post-hardening or thermal-aging-induced contraction. Furthermore, when plotting failure times against temperature, we observed that the hardness, adhesive strength, and water absorption rate were the predominant factors up to 120 ℃. Beyond this temperature, the tensile properties were the primary contributing factors. In contrast, the dielectric constant and loss tangent, which are vital for reducing signal interference in electric devices, exhibited positive changes(decreases) with aging and could be excluded as failure factors. Our findings establish valuable correlations between physical properties and techniques for the accurate prediction of failure time, with broad implications for future product lifespans. This study is particularly advantageous for advancing elastic potting materials to satisfy the stringent requirements of reliable environments.

• Journal of Microbiology and Biotechnology
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• 제28권3호
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• pp.439-447
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• 2018

The aromatic compound p-hydroxybenzoate (PHBA) is an important material with multiple applications, including as a building block of liquid crystal polymers in chemical industries. The cytochrome P450 (CYP) enzymes are beneficial monooxygenases for the synthesis of chemicals, and CYP53A15 from fungus Cochliobolus lunatus is capable of executing the hydroxylation from benzoate to PHBA. Here, we constructed a system for the bioconversion of benzoate to PHBA in Escherichia coli cells coexpressing CYP53A15 and human NADPH-P450 oxidoreductase (CPR) genes as a redox partner. For suitable coexpression of CYP53A15 and CPR, we originally constructed five plasmids in which we replaced the N-terminal transmembrane region of CYP53A15 with a portion of the N-terminus of various mammalian P450s. PHBA productivity was the greatest when CYP53A15 expression was induced at $20^{\circ}C$ in $2{\times}YT$ medium in host E. coli strain ${\Delta}gcvR$ transformed with an N-terminal transmembrane region of rabbit CYP2C3. By optimizing each reaction condition (reaction temperature, substrate concentration, reaction time, and E. coli cell concentration), we achieved 90% whole-cell conversion of benzoate. Our data demonstrate that the described novel E. coli bioconversion system is a more efficient tool for PHBA production from benzoate than the previously described yeast system.