• Journal of Microbiology and Biotechnology
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• 제10권3호
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• pp.415-418
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• 2000

Productivity of a rice plant is greatly influenced by salt stress. One of the ways to achieve tolerance to salinity is to transfer genes encoding protective enzymes from other organisms, such as microorganisms. The bacterial gene, mtlD, which encodes mannitol-1-phosphate dehydrogenase (Mtl-DH), was introduced to the cytosol of a rice plant by an imbibition technique to overproduce mannitol. The germination and survival rate of the imbibed rice seeds were markedly increased by transferring the mtlD gene when it was delivered in either a pBIN19 or pBmin binary vector. When a polymerase chain reaction was performed with the genomic DNAs of the imbibed rice leaves as a template and with mtlD-specific primers, several lines were shown to contain an exogenous mtlD DNA. However, a reverse transcription (RT)-PCR analysis revealed that not all of them showed an expression of this foreign gene. This paper demonstrates that the growth and germination of rice plants transiently transformed with the bacterial gene, mtlD, are enhanced and these enhancements may have resulted from the experssion of the mtlD gene. The imbibition method empolyed in this study fulfills the requirements for testing the function of such a putative gene in vivo prior to the production of a stable transgenic plant.

• 대한기계학회논문집A
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• 제38권10호
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• pp.1139-1145
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• 2014

인체 골격의 모델생성과 형상변동을 파악하는 것은 생체역학의 응용분야에서 중요한 부분을 차지한다. 본 논문에서는 3 차원 대퇴골 모델의 데이터베이스로부터 대퇴골의 형상변동을 통계적으로 분석하고, 추출된 주요 파라미터를 사용하여 대퇴골의 형상을 직관적으로 모델링 할 수 있는 방법을 제안한다. 이를 위해서 먼저 통계적 기법 중에 하나인 주성분 분석(PCA)을 이용하여 대퇴골의 형상변동을 파악하였다. 주성분 분석을 수행하기 위해서는 3 차원 대퇴골 모델 간에 토폴로지(Topology)의 일치가 필요하다. 따라서 대퇴골의 형상에 해부학적 기준점(Landmark)을 정의하여 템플릿 모델이 대상 대퇴골 모델로 변형되기 위한 방향을 결정한 후 곡면 피팅(Surface fitting)을 수행하였다. 다음으로 주성분 분석을 통해 도출된 주성분과 대퇴골의 형상을 대표할 수 있는 해부학적 파라미터와의 상관관계를 정의하였다. 마지막으로 해부학적 파라미터로 대퇴골 모델의 생성 및 형상변동을 가시화 할 수 있는 프로그램을 개발하였다.

• Design & Manufacturing
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• 제16권3호
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• 한국재료학회지
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• 제22권3호
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• pp.118-122
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• 2012

We synthesized porous $Co_3O_4/RuO_2$ composite using the soft template method. Cetyl trimethyl ammonium bromide (CTAB) was used to make micell as a cation surfactant. The precipitation of cobalt ion and ruthenium ion for making porosity in particles was induced by $OH^-$ ion. The porous $Co_3O_4/RuO_2$ composite was completely synthesiszed after anealing until $250^{\circ}C$ at $3^{\circ}C$/min. From the XRD ananysis, we were able to determine that the porous $Co_3O_4$/RuO2 composite was comprised of nanoparticles with low crystallinity. The shape or structure of the porous $Co_3O_4/RuO_2$ composite was studied by FE-SEM and FE-TEM. The size of the porous $Co_3O_4/RuO_2$ composite was 20~40 nm. From the FE-TEM, we were able to determine that porous cavities were formed in the composite particles. The electrochemical performance of the porous $Co_3O_4/RuO_2$ composite was measured by CV and charge-discharge methods. The specific capacitances, determined through cyclic voltammetry (CV) measurement, were ~51, ~47, ~42, and ~33 F/g at 5, 10, 20, and 50 mV/sec scan rates, respectively. The specific capacitance through charge-discharge measurement was ~63 F/g in the range of 0.0~1.0 V cutoff voltage and 50 mAh/g current density.

• 대한공간정보학회지
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• 제12권4호
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• pp.61-68
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• 2004

본 연구에서는 도로 노면표지를 이용하여 도심지에서 3차원 도로정보를 자동으로 취득하기 위한 기술을 제안하였다. 제안된 방법은 다음의 주요 3단계로 구성되어 있다. 첫 단계는 두 장의 항공사진에 나타난 도로 노면표지를 추출하는 것이고, 두 번째는 추출된 노면표지 중 동일한 표지를 매칭하는 것이다. 마지막 단계는 항공사진의 외부표정요소를 이용하여 노면표지의 3차원 위치좌표를 얻는 것이다. 마지막 단계는 공선조건식을 사용하여 수행될 수 있기 때문에, 본 연구에서는 처음 두 단계에 연구의 초점을 맞추었다. 차로 경계선을 추출하기 위해 노면표지의 형상 정보와 공간 관계를 이용하였고, 템플릿 매칭을 추가적으로 사용하여 방향표시를 추출하였다. 그리고 도로의 3차원 위치정보를 취득하기 위해 도로 노면표지에 적합한 관계형 매칭(relational matching)기법을 사용하였다. 추출정확도는 시각적인 평가를 통해 수행하였고, 위치정확도는 수치사진 측량시스템을 통해 얻은 참고자료와 비교를 통해 수행하였다.

• 대한의생명과학회지
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• 제25권1호
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• pp.99-106
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• 2019

Amyloid positron emission tomography (PET) allows early and accurate diagnosis in suspected cases of Alzheimer's disease (AD) and contributes to future treatment plans. In the present study, a method of implementing a diagnostic system to distinguish ${\beta}$-Amyloid ($A{\beta}$) positive from $A{\beta}$ negative with objectiveness and accuracy was proposed using a machine learning approach, such as the Principal Component Analysis (PCA) and Support Vector Machine (SVM). $^{18}F$-Florbetaben (FBB) brain PET images were arranged in control and patients (total n = 176) with mild cognitive impairment and AD. An SVM was used to classify the slices of registered PET image using PET template, and a system was created to diagnose patients comprehensively from the output of the trained model. To compare the per-slice classification, the PCA-SVM model observing the whole brain (WB) region showed the highest performance (accuracy 92.38, specificity 92.87, sensitivity 92.87), followed by SVM with gray matter masking (GMM) (accuracy 92.22, specificity 92.13, sensitivity 92.28) for $A{\beta}$ positivity. To compare according to per-subject classification, the PCA-SVM with WB also showed the highest performance (accuracy 89.21, specificity 71.67, sensitivity 98.28), followed by PCA-SVM with GMM (accuracy 85.80, specificity 61.67, sensitivity 98.28) for $A{\beta}$ positivity. When comparing the area under curve (AUC), PCA-SVM with WB was the highest for per-slice classifiers (0.992), and the models except for SVM with WM were highest for the per-subject classifier (1.000). We can classify $^{18}F$-Florbetaben amyloid brain PET image for $A{\beta}$ positivity using PCA-SVM model, with no additional effects on GMM.

• 한국재료학회지
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• 제32권5호
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• pp.258-263
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• 2022

Porous ceramics have the advantages of low density, low thermal conductivity, and excellent mechanical properties. Among porous ceramic manufacturing methods, the replica template method allows the easy manufacturing of porous filters with the highest porosity and pores of the desired size, but it also has the disadvantage that the resulting filters have low mechanical strength. To overcome this shortcoming, mullite (3Al₂O₃·2SiO₂) whiskers, which have excellent thermal stability and high mechanical strength, were introduced in porous ceramic structure. The mullite whiskers were synthesized using a composition of Al₂O₃, flyash and MoO₃. The morphologies and crystal structures of the mullite whiskers with MoO₃ contents were investigated in detail. When the porous ceramic with mullite whiskers was fabricated using 20 wt% MoO₃ catalyst the most uniform microstructure was obtained, and the mullite whiskers showed the highest aspect ratio of 47.03. The porosity and compressive strength of the fabricated porous ceramic were 82.12 % and 0.83 MPa, respectively.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2384-2393
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• 2018

Porous alginate-based hydrogel beads (porous ABH) have been prepared through a facile and sustainable template-assisted method using nano-calcium carbonate and nano-$CaCO_3$ as pore-directing agent for the efficient capture of methylene blue (MB). The materials were characterized by various techniques. The sorption capacities of ABH towards MB were compared with pure sodium alginate (ABH-1:0) in batch and fixed-bed column adsorption studies. The obtained adsorbent (ABH-1:3) has a higher BET surface area and a smaller average pore diameter. The maximum adsorption capacity of ABH-1:3 obtained from Langmuir model was as high as $1,426.0mg\;g^{-1}$. The kinetics strictly followed pseudo-second order rate equation and the adsorption reaction was effectively facilitated, approximately 50 minutes to achieve adsorption equilibrium, which was significantly shorter than that of ABH-1:0. The thermodynamic parameters revealed that the adsorption was spontaneous and exothermic. Thomas model fitted well with the breakthrough curves and could describe the dynamic behavior of the column. More significantly, the uptake capacity of ABH-1:3 was still higher than 75% of the maximum adsorption capacity even after ten cycles, indicating that this novel adsorbent can be a promising adsorptive material for removal of MB from aqueous solution under batch and continuous systems.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.137-145
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• 2021

Among the non-precious metal catalysts, iron-nitrogen doped carbon (Fe-N/C) catalysts have been recognized as the most promising candidates for an alternative to Pt-based catalysts for the oxygen reduction reaction (ORR) under alkaline and acidic conditions. In this study, the nano replication method using mesoporous silica, which features tunable primary particle sizes and shape, is employed to prepare the mesoporous Fe-N/C catalysts with different shapes. Platelet SBA-15, irregular KIT-6, and spherical silica particle (SSP) were selected as a template to generate three different kinds of shapes of the mesoporous Fe-N/C catalyst. Physicochemical properties of mesoporous Fe-N/C catalysts are characterized by using small-angle X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy images. According to the electrochemical evaluation, there is no morphological preference of mesoporous Fe-N/C catalysts toward the ORR activity with half-cell configuration under alkaline electrolyte. By implementing X-ray photoelectron spectroscopy analysis of Fe and N atoms in the mesoporous Fe-N/C catalysts, it is possible to verify that the activity towards ORR highly depends on the portions of "Fe-N" species in the catalysts regardless of the shape of catalysts. It was suggested that active site distribution in the Fe-N/C is one important factor towards ORR activity.

• 한국전기전자재료학회논문지
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• 제36권1호
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• pp.10-15
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• 2023

The carbonaceous materials have attracted much attention for utilization of anode materials for lithium-ion batteries. Among them, hollow carbon spheres have great advantages (high specific capacity and good rate capability) to replace currently used graphite anode materials, due to their unique features such as high surface areas, high electrical conductivities, and outstanding chemical and thermal stability. Herein, we have synthesized various sizes of hollow carbon spheres by a facile hardtemplate method and investigated the anode properties for lithium-ion batteries. The obtained hollow carbon spheres have uniform diameters of 350 ~ 600 nm by varying the template condition, and they do not have any cracks after the optimization of the process. Increasing the diameter of hollow carbon spheres decreases their specific capacities, since the larger hollow carbon spheres have more useless spaces inside that could have a disadvantage for lithium storage. The hollow carbon spheres have outstanding rate and cyclic performance, which is originated from the high surface area and high electrical properties of the hollow carbon spheres. Therefore, hollow carbon spheres with smaller diameters are expected to have higher specific capacities, and the noble channel structures through various doping approaches can give the great possibility of high lithium storage properties.