• 설비공학논문집
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• 제25권8호
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• pp.432-437
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• 2013

The increase of greenhouse gas emission and decrease of fossil fuel are being caused by the indiscreet consumption of energy by people. Recently, green policy has been globally implemented to reduce energy consumption. This paper studied the research to reduce the energy consumption in buildings, by using the heat storage properties of PCM. PCM has to prevent leakage from the liquid state. Therefore, we prepared form stable PCM, by using the vacuum impregnation method. Three kinds of organic PCMs were impregnated into the structure of porous material. The characteristics of the composites were determined by using SEM, DSC, FTIR and TGA. SEM morphology showed the micro structure of silica fume/PCM. Also, thermal properties were examined by DSC and TGA analyses; and the chemical bonding of the composite was determined by FTIR analysis.

• 대한의용생체공학회:의공학회지
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• 제31권3호
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• pp.234-239
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• 2010

We have developed and reported several micro-spikes for minimally invasive biopsy. This paper presents a diagnosis protocol for micro-spike biopsy using paraffin-based tissue collecting tool. Using the proposed tissue collecting tool, which has a negative micro-spike structure in a porous chamber, the biopsied tissue in a micro-spike is effectively detached. The proposed diagnosis protocol prevents the loss of tissues in a paraffin embedding and sectioning process. Hence, it is compatible with conventional histopathology without additional reagents and processes. The gastro-intestinal tissue of a pig is biopsied in an in vivo environment, and then it is detached from a micro-spike using the paraffin-based tissue collecting tool. A histopathological photomicrograph of the detached tissue is acquired with the proposed diagnosis protocol. The acquired image offers clinical quality. This result shows that the paraffin-based tissue collecting tool is applicable to the medical practice.

• ETRI Journal
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• 제40권2호
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• pp.275-282
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• 2018

Flash reduction of graphene oxide is an efficient method for producing high quality reduced graphene oxide under room temperature ambient conditions without the use of hazardous reducing agents (such as hydrazine and hydrogen iodide). The entire process is fast, low-cost, and suitable for large-scale fabrication, which makes it an attractive process for industrial manufacturing. Herein, we present a simple fabrication method for a flexible in-plane graphene micro-supercapacitor using flash light irradiation. All carbon-based, monolithic supercapacitors with in-plane geometry can be fabricated with simple flash irradiation, which occurs in only a few milliseconds. The thinness of the fabricated device makes it highly flexible and thus useful for a variety of applications, including portable and wearable electronics. The rapid flash reduction process creates a porous graphene structure with high surface area and good electrical conductivity, which ultimately results in high specific capacitance ($36.90mF\;cm^{-2}$) and good cyclic stability up to 8,000 cycles.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.306-306
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• 2007

The surface was transformed to porous titanium oxide by the anodization of pure titanium. Titanium was anodized in non-aqueous and aqueous electrolytes at different potentials between 5 V and 150 V. Various electrolytes were compose of ethylene glycerol, $H_2SO_4,\;NH_4F\;and\;H_2O$. We obtained titania nanotube arrays on the micro pore of titanium. Micro pores and nano tubes were obtained by anodization at high potentials and low potentials, respectively. Morphologies of nanotubes and micro pore were characterized by FE-SEM. The unique surface structure is very attractive to electrical and medical applications such as gas sensor, biosensor, dental implant and stent.

• Journal of Electrochemical Science and Technology
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• 제2권2호
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• pp.124-129
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• 2011

A simple process of fabricating micropillar structure and its influence upon enhancing electrochemical biosensor response were studied in this work. Conducting polymer PEDOT was used as a base material in formulating a composite with PVA. Micro porous PC membrane filter was used as a template for the micropillar of the composite on ITO electrode. This structure could provide plenty of encapsulating space for enzyme species. After dosing enzyme solution into this space, Nafion film tent was cast over the pillar structure to complete the micropillar cavity structure. In this way, the encapsulation of enzyme could be accomplished without any chemical modification. The amount of enzyme species was easily controllable by varying the concentration of the dosing solution. The more amount of enzyme is stored in the sensor, the higher the electrochemical response is produced. One more reason for the sensitivity improvement comes from the large surface area of the micropillar structure. Application of 0.7 V produced the best current response under the condition of pH 7.4. This biosensor showed linear response to the glucose in 0.1~1 mM range with the average sensitivity of $14.06{\mu}A/mMcm^2$. Detection limit was 0.01 mM based on S/N = 3.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.2.2-2.2
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• 2011

The central strategy in tissue engineering involves a biomaterial scaffold as a delivery carrier of cells and a depot to deliver bioactive molecules. The ability of scaffolds to control cellular response to direct particular repair and regeneration processes is essential to obtain functional tissue engineering constructs. Therefore, many efforts have been made to understand local interactions of cells with their extracellular matrix (ECM) microenvironment and exploit these interactions for designing an ideal scaffold mimicking the chemical, physiological, and structural features of native ECM. ECM is composed of a number of biomacromolecules including proteins, glycosaminoglycans, and proteoglycans, which are assembled together to form complex 3-dimensional network. Electrospinning is a process to generate highly porous 3-dimensional fibrous structure with nano to micro scaled-diameter, which can closely mimic the structure of ECM. In this presentation, our approaches to develop biomimetic electrospun fibers for modulation of cell function will be discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1697-1699
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• 2008

The purpose of tissue engineering is to repair or replace damaged tissues or organs by a combination of cells, scaffold, suitable biochemical and physio-chemical factors. Among the three components, the biodegradable scaffold plays an important role in cell attachment and migration. In this study, we designed 3D porous scaffold by Rapid Prototyping (RP) system and fabricated layer-by-layer 3D structure using Polycarprolactone (PCL) - one of the most flexible biodegradable polymer. Furthermore, the physical and mechanical properties of the scaffolds were evaluated by changing the pore size and the strand diameter of the scaffold. We changed nozzle diameter (strand diameter) and strand to strand distance (pore size) to find the effect on the mechanical property of the scaffold. And the surface morphology, inner structure and storage modulus of PCL scaffold were analyzed with SEM, Micro-CT and DMA.

• Carbon letters
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• 제28권
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• pp.116-120
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• 2018

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature ($600-850^{\circ}C$) on the $CO_2$ adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of $1488m^2g^{-1}$ was achieved at an activation temperature of $800^{\circ}C$ (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to $850^{\circ}C$. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, $CO_2$ adsorption isotherms showed that AC-800 exhibited the best $CO_2$ adsorption capacity of $110mg\;g^{-1}$ at 298 K and 1 bar.

• 전기화학회지
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• 제2권3호
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• pp.130-133
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• 1999

본 연구에서는 음주 측정에 적용할 수 있는 다공질 실리콘층으로 된 저농도의 캐퍼시턴스형 알코올 가스 측정용 센서를 제작하고, 상온에서 그 특성을 측정하였다. 기존의 $SnO_2$등의 금속 산화물 반도체를 이용한 센서는 저농도의 알코올을 정확하게 검지하기에 어려울 뿐만 아니라 감도를 높이기 위해 $200\~400^{\circ}C$로 가열이 필요하였다. 이에 비해 다공질 실리콘층을 이용한 센서는 넓은 표면적을 갖고 있어 상온에서도 감도가 양호할 뿐만 아니라 집적화 센서로 제작이 용이한 점을 갖고 있다. 실험은 증류수에 희석한 알코올 수용액을 체온과 같은 $36^{\circ}C$를 비롯하여 25와 $45^{\circ}C$로 유지한 상태에서 0에서 $0.5\%$의 농도범위에 대해서 $0.05\%$의 간격으로 120 Hz와 1 kHz의 두 주파수에서 측정하였다. 그 결과, 양호한 선형성과 함께 120 Hz의 주파수에서 측정하였을 때, $0.1\%$의 알코올 농도의 증분마다 $25,\;36,\;45^{\circ}C$의 알코올 수용액의 온도에 대해 각각 1.1, 2.6 및 $4.6\%$로 캐퍼시턴스의 증가율을 보였다.

• Corrosion Science and Technology
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• 제20권5호
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• pp.249-255
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• 2021

In this work, we proposed a facile method to fabricate the three-dimensional porous copper current collector (3D Cu CC) for a Si-dominant anode in a Li-ion battery (LiB). The 3D Cu CC was prepared by combining chemical etching and thermal reduction from a planar copper foil. It had a porous layer employing micro-sized Cu balls with a large surface area. In particular, it had strengthened attachment of Si-dominant active material on the CC compared to a planar 2D copper foil. Moreover, the increased contact area between a Si-dominant active material and the 3D Cu could minimize contact loss of active materials from a CC. As a result of a battery test, Si-dominant active materials on 3D Cu showed higher cyclic performance and rate-capability than those on a conventional planar copper foil. Specifically, the Si electrode employing 3D Cu exhibited an areal capacity of 0.9 mAh cm^-2 at the 300^th cycles (@ 1.0 mA cm^-2), which was 5.6 times higher than that on the 2D copper foil (0.16 mAh cm^-2).