• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.471.1-471.1
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• 2014

염료감응형 태양전지(DSSC)는 다양한 태양전지 중, 가장 환경친화적이고, 생산단가도 낮을 뿐만 아니라 다양한 색상과 투광성을 확보할 수 있어 많은 연구가 진행되어왔다. 하지만 액체전해질을 사용하는 기존 염료감응형 태양전지는 높은 휘발성과 열 팽창 수축에 따른 전해질 누액의 문제점으로 인하여 최근에는 고체전해질을 이용한 염료감응형 태양전지의 개발이 활발히 이루어지고 있다. 또한 기존 염료보다 높은 흡광계수와 넓은 흡수스펙트럼을 지닌 페로브스카이트가 개발되어 현재 많은 관심이 주목되고 있다. 본 연구에서는 $TiO_2$ 제조상의 중간생성물인 Metatitanic acid (MTA)를 이용하여 광전극을 형성하고 열처리 온도에 따른 나노입자의 소성거동평가을 평가하였고 시차열중량 분석, 결정상 확인을 하고 염료감응 태양전지에 적용하였다. MTA 나노입자를 Field Emission Transmission Electron Microscopy (FE-TEM), Barrett-Joyner-Halenda (BJH pore size distribution)과 Brunauer-Emmet-Teller (BET) 분석을 통해 소성거동을 평가하고, Thermogravimetry and differential thermal analysis (TG-DTA)를 통해 열중량 측정을 하였으며, X-ray Diffraction (XRD) 분석을 통해 결정상을 확인하였다. 또한 Fourier-transform infrared (FT-IR) spectroscopy를 통해 MTA 나노입자의 표면분석을 하였다. 형성된 MTA 광전극을 페로브스카이트 염료에 적용하여 5%의 효율을 달성하였다.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.193-196
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• 2009

Mesoporous $TiO_2$ material was synthesized from diblock copolymers with ethylene oxide chains via a sol-gel process in aqueous solution. The properties of these materials were characterized with several analytical techniques including field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), wide angle X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and Barrett-Joyner-Halenda (BJH) analysis. The mesoporous $TiO_2$ materials calcined at 400${^{\circ}C}$ were found to have specific surface areas 212 $m^2g^-1$, average pore sizes 6.2 nm, and their average crystal sizes were found to be 8.2 nm. The photocatalytic activity of mesoporous $TiO_2$ was characterized with UV-Vis spectroscopy, and it was found to be 5.8 times higher than that of Degussa P25 $TiO_2$ (P25). For deactivation of Escherichia coli, mesoporous $TiO_2$ also has high photocatalytic inactivity than that of P25. Such a high photocatalytic activity is explained with large surface area and small crystal size with wormhole-like mesoporous structure.

• 대한화학회지
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• 제57권1호
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• pp.104-108
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• 2013

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents.

• 정보학연구
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• 제6권1호
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• pp.49-63
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• 2003

21세기 들어 e-비즈니스의 확산과 더불어 인터넷이라는 개방형 커뮤니케이션구조를 기반으로하는 네트워크기술의 도약적 발전으로 인해 수많은 중개형 e-마켓플레이스들이 등장하였다. 하지만, 이와같은 중개형 e-마켓플레이스들을 통한 기업간 전자상거래를 규모가 예상과 달리 저조함에 따라 현재 인지도가 높은 사이트들조차도 사업을 정리하거나 전환하고 있는 실정이다. 본 연구에서는 기업내부 혹은 기업간 e-비즈니스의 핵심거래기반으로서 논의되어왔던 e-마켓플레이스를 기업에서의 정보기술활용이라는 역사적 관점에서 재조명해보았다. 이를 통해 기업의 e-비즈니스 거래기반으로서의 중개형 e-마켓플레이스들의 위상과 갖추어야 할 비즈니스적 특성을 제시하였다.

• Elastomers and Composites
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• 제39권4호
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• pp.281-285
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• 2004

이 연구는 열분석법을 이용하여 간단하게 자유 라디칼 중합의 활성화 에너지를 결정하는 방법을 부틸 아크릴레이트을 모델로 하여 구했다. 활성화 에너지는 Kissinger, Osawa 및 half-width법인 다수의 주사 속도법 (multiple scanning-rate method)을 이용하여 $1^{\circ}C/min,\;2^{\circ}C/min,\;5^{\circ}C/min$, 그리고 $10^{\circ}C/min$로 측정하였으며 단수 주사 속도법인 Barret 법을 이용하여 구하였다. 열분석법에 의해 구해진 중합반응의 활성화 에너지는 개시반응, 성장반응 및 종결반응의 각각의 활성화 에너지에서 계산된 전체 중합반응에서의 활성화 에너지와 가깝게 접근하였다.

• Clinical Endoscopy
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• 제56권6호
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• pp.681-692
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• 2023

In general, gastroesophageal reflux disease (GERD) is diagnosed clinically based on typical symptoms and/or response to proton pump inhibitor treatment. Upper gastrointestinal endoscopy is reserved for patients presenting with alarm symptoms, such as dysphagia, odynophagia, significant weight loss, gastrointestinal bleeding, or anorexia; those who meet the criteria for Barrett's esophagus screening; those who report a lack or partial response to proton pump inhibitor treatment; and those with prior endoscopic or surgical anti-reflux interventions. Newer endoscopic techniques are primarily used to increase diagnostic yield and provide an alternative to medical or surgical treatment for GERD. The available endoscopic modalities for the diagnosis of GERD include conventional endoscopy with white-light imaging, high-resolution and high-magnification endoscopy, chromoendoscopy, image-enhanced endoscopy (narrow-band imaging, I- SCAN, flexible spectral imaging color enhancement, blue laser imaging, and linked color imaging), and confocal laser endomicroscopy. Endoscopic techniques for treating GERD include esophageal radiofrequency energy delivery/Stretta procedure, transoral incisionless fundoplication, and endoscopic full-thickness plication. Other novel techniques include anti-reflux mucosectomy, peroral endoscopic cardiac constriction, endoscopic submucosal dissection, and endoscopic band ligation. Currently, many of the new endoscopic techniques are not widely available, and their use is limited to centers of excellence.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3576-3582
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• 2014

Zeolite-templated carbons (ZTCs), which have high specific surface area, were prepared by a conventional templating method using microporous zeolite-Y for catalyst supports in direct methanol fuel cells. The ZTCs were synthesized at different temperatures to investigate the characteristics of the surface produced and their electrochemical properties. Thereafter, Pt-Ru was deposited at different carbonization temperatures by a chemical reduction method. The crystalline and structural features were investigated using X-ray diffraction and scanning electron microscopy. The textural properties of the ZTCs were investigated by analyzing $N_2$/77 K adsorption isotherms using the Brunauer-Emmett-Teller equation, while the micro- and meso-pore size distributions were analyzed using the Barrett-Joyner-Halenda and Harvarth-Kawazoe methods, respectively. The surface morphology was characterized using transmission electron microscopy and inductively coupled plasma-mass spectrometry. The electrochemical properties of the Pt-Ru/ZTCs catalysts were also analyzed by cyclic voltammetry measurements. From the results, the ZTCs carbonized at $900^{\circ}C$ show the highest specific surface areas. In addition, ZTC900-PR led to uniform dispersion of Pt-Ru on the ZTCs, which enhanced the electro-catalytic activity of the Pt-Ru catalysts. The particle size of ZTC900-PR catalyst is about 3.4 nm, also peak current density from the CV plot is $12.5mA/cm^2$. Therefore, electro-catalytic activity of the ZTC900-PR catalyst is higher than those of ZTC1000-PR catalyst.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권5호
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• pp.873-887
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• 2015

The springing response of a large blunt ship was considered to be influenced by a second order interaction between the incoming irregular wave and the blunt geometry of the forebody of the ship. Little efforts have been made to simulate this complicated fluid-structure interaction phenomenon under irregular waves considering the second order effect; hence, the above mentioned premise still remains unproven. In this paper, efforts were made to quantify the second order effect between the wave and vibrating flexible ship structure by analyzing the experimental data obtained through the model basin test of the scaled-segmented model of a large blunt ship. To achieve this goal, the measured vertical bending moment and the wave elevation time history were analyzed using a higher order spectral analysis technique, where the quadratic interaction between the excitation and response was captured by the cross bispectrum of two randomly oscillating variables. The nonlinear response of the vibrating hull was expressed in terms of a quadratic Volterra series assuming that the wave excitation is Gaussian. The Volterra series was then orthogonalized using Barrett's procedure to remove the interference between the kernels of different orders. Both the linear and quadratic transfer functions of the given system were then derived based on a Fourier transform of the orthogonalized Volterra series. Finally, the response was decomposed into a linear and quadratic part to determine the contribution of the second order effect using the obtained linear and quadratic transfer functions of the system, combined with the given wave spectrum used in the experiment. The contribution of the second order effect on the springing response of the analyzed ship was almost comparable to the linear one in terms of its peak power near the resonance frequency.

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1437-1443
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• 2018

In this work, $SnO_2$ modified with reduced graphene oxide (rGO) and carbon nanotubes (CNTs) separately and combined sensitized by using the co-precipitation method and their sensing behavior toward ethanol vapor at room temperature were investigated. An interdigitated electrode (IDE) gold substrate is very expensive compared to a fluorine doped tin oxide (FTO) substrate; hence, we used the latter to reduce the fabrication cost. The structure and the morphology of the studied materials were characterized by using differential thermal analyses (DTA) and thermogravimetric analysis (TGA), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller surface area and Barrett-Joyner-Halenda (BJH) pore size measurements. The studied composites were subjected to ethanol in its gas phase at concentrations from 10 to 200 ppm. The present composites showed high-performance sensitivity for many reasons: the incorporation of $SnO_2$ and CNTs which prevents the agglomeration of rGO sheets, the formation of a 3D mesopourus structure and an increase in the surface area. The decoration with rGO and CNTs led to more active sites, such as vacancies, which increased the adsorption of ethanol gas. In addition, the mesopore structure and the nano size of the $SnO_2$ particles allowed an efficient diffusion of gases to the active sites. Based on these results, the present composites should be considered as efficient and low-cost sensors for alcohol.

• Journal of Digestive Cancer Research
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• 제4권1호
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• pp.1-9
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• 2016

The abundance of multi-drug resistance ATPase binding cassette and deranged self-renewal pathways shown in cancer stem cells (CSCs) played a crucial role in tumorigenesis, tumor resistance, tumor recurrence, and tumor metastasis. Therefore, elucidation of CSCs biology can improve diagnosis, enable targeted treatment, and guide the follow up of GI cancer patients. In order to achieve chemoquiescence, seizing cancer through complete ablation of CSCs, CSCs are rational targets for the design of interventions that will enhance responsiveness to traditional therapeutic strategies and contribute in the prevention of local recurrence as well as metastasis. However, current cancer treatment strategies fail to either detect or differentiate the CSCs from their non-tumorigenic progenies mostly due to the absence of specific biomarkers and potent agents to kill CSCs. Recent advances in knowledge of CSCs enable to produce several candidates to ablate CSCs in gastrointestinal (GI) cancers, especially cancers originated from inflammation-driven mutagenesis such as Barrett's esophagus (BE), Helicobacter pylori-associated gastric cancer, and colitis-associated cancer (CAC). Our research teams elucidated through revisiting old drugs that proton pump inhibitor (PPI) and potassium competitive acid blocker (p-CAB) beyond authentic acid suppression, chloroquine for autophage inhibition, sonic hedgehog (SHH) inhibitors, and Wnt/β-catenin/NOTCH inhibitor can ablate CSCs specifically and efficiently. Furthermore, nanoformulations of these molecules could provide an additional advantage for more selective targeting of the pathways existing in CSCs just like current molecular targeted therapeutics and sustained action, while normal stem cells intact. In this review article, the novel approach specifically to ablate CSCs existing in GI cancers will be introduced with the introduction of explored mode of action.