• 센서학회지
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• 제20권1호
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• pp.1-7
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• 2011

Undoped and Sb-doped $SnO_2$ nanofibers were prepared by electrospinning and their responses to $H_2$, CO, $CH_4$, $C_3H_8$, and $C_2H_5OH$ were measured. In the undoped $SnO_2$ nanofibers, the gas response ($R_a/R_g$, $R_a$: resistance in air, $R_g$: resistance in gas) to 100 ppm $C_2H_5OH$ was very high(33.9), while that to the other gases ranged from 1.6 to 2.2. By doping with 2.65 wt% Sb, the response to 100 ppm $C_2H_5OH$ was decreased to 4.5, whereas the response to $H_2$ was increased to 3.0. This demonstrates the possibility of detecting a high $H_2$ concentration with minimum interference from $C_2H_5OH$ and the potential to control the gas selectivity by Sb doping.

• 인터넷정보학회논문지
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• 제15권4호
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• pp.9-20
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• 2014

대상의 동작을 잘 예측하는 것은 사회적 상호작용과 의사결정 컨텍스트 이해의 핵심이다. 본 연구는 동작 인식 과정에서 인간 뇌 시각인지 과정을 모방한 방법으로 관절 동작의 동작 순서 패턴을 학습하는 컴퓨팅 모델을 제안하였다. 제안 방법의 핵심은 뇌에서 동작 인지 자극을 처리하는 신경생리학적 IT, MT, STS의 피질 기능과 특정 시각 신경 회로 네트워크 기능을 모방하여 비지도 방법으로 동작 순서를 학습한 후 동작을 예측, 인식하는 것이다. 실험을 통해 제안 모델이 어떻게 연속적으로 입력되는 비디오에서 의미있는 동작 스냅샷 뿐 아니라 중요한 동작 패턴을 자동으로 선택하는 지를 제시하였다. 이 핵심 움직임은 학습 네트워크가 정적 시점에서 정지 영상에 함축된 동작을 인식하는지를 증명하는데 이용하는 관절 자세이다. 또한 STS 피질 영역에서 어떻게 정지와 움직임 입력을 통합하는지를 모방하여 학습하고, 학습한 피드백 연결이 차후 동작의 입력 순서를 어떻게 예측하는지를 제시하였다. 네트워크 시뮬레이션을 통해 동작 인식에 대한 제안 모델의 우수성을 입증하였다.

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1153-1159
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• 2013

A novel solid-contact indium(III)-selective sensor based on bis-(1H-benzimidazole-5-methoxy-2-[(4-methoxy-3, 5-dimethyl-1-pyridinyl) 2-methyl]) thiosulfinate, known as an omeprazole dimer (OD) and a neutral ionophore, was constructed, and its performance characteristics were evaluated. The sensor was prepared by applying a membrane cocktail containing the ionophore to a graphite rod pre-coated with polyethylene dioxythiophene (PEDOT) conducting polymer as the ion-to-electron transducer. The membrane contained 3.6% OD, 2.3% oleic acid (OA) and 62% dioctyl phthalate (DOP) as the solvent mediator in PVC and produced a good potentiometric response to indium(III) ions with a Nernstian slope of 19.09 mV/decade. The constructed sensor possessed a linear concentration range from $3{\times}10^{-7}$ to $1{\times}10^{-2}$ M and a lower detection limit (LDL) of $1{\times}10^{-7}$ M indium(III) over a pH range of 4.0-7.0. It also displayed a fast response time and good selectivity for indium(III) over several other ions. The sensor can be used for longer than three months without any considerable divergence in potential. The sensor was utilized for direct and flow injection potentiometric (FIP) determination of indium(III) in alloys. The parameters that control the flow injection method were optimized. Indium(III) was quantitatively recovered, and the results agreed with those obtained using atomic absorption spectrophotometry, as confirmed by the f and t values. The sensor was also utilized as an indicator electrode for the potentiometric titration of fluoride in the presence of chloride, bromide, iodide and thiocyanate ions using indium(III) nitrate as the titrant.

• 한국임상수의학회지
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• 제22권2호
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• pp.119-124
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• 2005

This study was performed to validate the procedure of transarterial embolization of the renal artery (TAE-RA) and sclerotherapy of renal pelvis using iohexol-ethanol solution in dogs with unilateral experimental hydronephrosis. Experimental hydronephrosis was induced by unilateral ureter ligation for 20 days in five Beagle dogs. Renal artery embolization with iohexol-ethanol solution was performed using selective catheterization technique in the hydronephrotic kidney and sclerotherapy was done by injection of the iohexol-ethanol solution through percutaneously placed pig-tail catheter. EKG, $SpO_2$ body temperature, pulse, and respiratory rate were within normal ranges during procedures. Average pure ethanol dose for renal artery embolization was $1.1\pm0.3ml/kg$. Renal artery embolization was confirmed by the detection of no blood flow signal at the interlobar and arcuate artery using color Doppler ultrasonography. There were no dogs expired after TAE-RA and sclerotherapy and no side effects associated with regurgitation of iohexol-ethanol solution. The value of BUN, creatinine, ALT, AST, Ca, P in five dogs were within normal range during the experiment period. Ultrasonographically, the mean longitudinal and transverse length and the depth of the embolized kidney significantly decreased at 28 days after TAE-RA. We may conclude that TAE-RA and sclerotherapy with iohexol-ethanol solution is an effective methods for the treatment of unilateral hydronephrosis in dogs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.636-636
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• 2013

Since first discovery of strong Raman spectrum of molecules adsorbed on rough noble metal, surface enhanced Raman scattering (SERS) has been widely used for detection of molecules with low concentration. Surface plasmons at noble metal can enhance Raman spectrum and using Au nanostructures as substrates of SERS has advantages due to it has chemical stability and biocompatibility. However, the photoluminescence (PL) background from Au remains a problem because of obtaining molecular vibration information. Recently, graphene, two-dimensional atomic layer of carbon atoms, is also well known as PL quenchers for electronic and vibrational excitation. In this study, we observed SERS of single layer graphene on or under monolayer of Au nanoparticles (NPs). Single layer graphene is grown by chemical vapor deposition and transferred onto or under the monolayer of Au NPs by using PMMA transfer method. Monolayer of Au NPs prepared using Langmuir-Blodgett method on or under graphene surface provides closed and well-packed monolayer of Au NPs. Scanning electron microscopy (SEM) and Raman spectroscopy (WItec, 532 nm) were performed in order to confirm effects of Au NPs on enhanced Raman spectrum. Highly enhanced Raman signal of graphene by Au NPs were observed due to many hot-spots at gap of closed well-packed Au NPs. The results showed that single layer graphene provides larger SERS effects compared to multilayer graphene and the enhancement of the G band was larger than that of 2D band. Moreover, we confirm the appearance of D band in this study that is not clear in normal Raman spectrum. In our study, D band appearance is ascribed to the SERS effect resulted from defects induced graphene on Au NPs. Monolayer film of Au NPs under the graphene provided more highly enhanced graphene Raman signal compared to that on the graphene. The Au NPs-graphene SERS substrate can be possibly applied to biochemical sensing applications requiring highly sensitive and selective assays.

• 대한화학회지
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• 제36권3호
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• pp.393-404
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• 1992

새로운 효소반응기를 쓰는 요소 정량용 연속${\cdot}$자동화 장치의 감응성질을 조사하였다. 효소반응기는 지지체인 nylon-6입자(42∼48 mesh)를 teflon관(안지름 2mm, 길이 20cm)에 충전시키고, 이 지지체의 표면에 공유결합제인 glutaraldehyde로 urease를 고정화시켜서 제작하였다. 연속${\cdot}$자동화장치는 효소반응기, 기체투석기 및 지시전극인 관형 PVC-nonactin막 암모늄 이온 선택성 전극을 차례로 연결하여 만들었다. 이 장치를 써서 요소를 정량할 때 감응특성은 다음과 같다. 곧 직선감응 농도범위는 $5.5{\times}10^{-6}$~$2.4{\times}10^{-3}M$, 감응기울기는 57.8 mV/decade, 검출한계는 $1.5{\times}10^{-6}M$, 효소반응기의 전환백분율은 80.8%이었다. 효소반응기의 최적 완충용액은 0.01M Tris-HCl 완충용액(pH 7.0∼7.8)과 0.01M 인산염 완충용액(pH 6.9∼7.5)이었고, 수명은 150일 정도였다. 또한 다른 생리활성물질의 방해는 없었다.

• 제어로봇시스템학회논문지
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• 제15권5호
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• pp.457-464
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• 2009

The weak classifier of AdaBoost algorithm is a central classification element that uses a single criterion separating positive and negative learning candidates. Finding the best criterion to separate two feature distributions influences learning capacity of the algorithm. A common way to classify the distributions is to use the mean value of the features. However, positive and negative distributions of Haar-like feature as an image descriptor are hard to classify by a single threshold. The poor classification ability of the single threshold also increases the number of boosting operations, and finally results in a poor classifier. This paper proposes a weak classifier that uses multiple criterions by adding a probabilistic criterion of the positive candidate distribution with the conventional mean classifier: the positive distribution has low variation and the values are closer to the mean while the negative distribution has large variation and values are widely spread. The difference in the variance for the positive and negative distributions is used as an additional criterion. In the learning procedure, we use a new classifier that provides a better classifier between them by selective switching between the mean and standard deviation. We call this new type of combined classifier the "Mixed Weak Classifier". The proposed weak classifier is more robust than the mean classifier alone and decreases the number of boosting operations to be converged.

• 대한화학회지
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• 제55권1호
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• pp.46-49
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• 2011

감도가 높고 선택적인 추출-분광광도법은 미량의 시메티딘의 측정을 위해 개발되어 왔다. 이 방법은 클로로포름안에 브로모티몰 블루(BTB)와 함께 이온 쌍으로 시메티딘의 추출에 기초했다. 그리고 417 nm에서 흡광도를 측정하고 있다. pH, BTB의 농도, 클로로포름의 부피, 섞는 시간과 같은 다른 변수들의 효과를 연구하였다. 또한, 추출에서 간섭이온의 효과도 연구하였다. 보정곡선은 0.9997의 상관계수와 함께 0.25~8 ug/mL의 범위에서 선형이다. 3Sb에 기초한 검출한계는 0.14 ug/mL이고 시메티딘의 0.1과 4.0 ug/mL의 10번 측정에 대한 상대표준편차는 3.2와 1.49%이었다. 제안된 방법은 좋은 회수와 함께 약제 샘플에서 시메티딘의 측정에 적용되었다.

• Archives of Pharmacal Research
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• 제24권4호
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• pp.307-311
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• 2001

The activation of NF-$\kappa$B induced by kojic Acid, an inhibitor of tyrosinase for biosynthesis of melanin in melanocytes, was investigated in human transfectant HaCaT and SCC-13 cells. These two keratinocyte cell lines transfected with pNF-$\kappa$B-SEAP-NPT plasmid were used to determine the activation of NF-$\kappa$B. Transfectant cells release the secretory alkaline phosphatase (SEAP) as a transcription reporter in response to the NF-$\kappa$B activity and contain the neomycin phosphotransferase (NPT) gene for the dominant selective marker of geneticin resistance. NF-$\kappa$B activation was measured in the SEAP reporter gene assay using a fluorescence detection method. Kojic Acid showed the inhibition of cellular NF-$\kappa$B activity in both human keratinocyte transfectants. It could also downregulate the ultraviolet ray (UVR)-induced activation of NF-$\kappa$B expression in transfectant HaCaT cells. Moreover, the inhibitory activity of kojic Acid in transfectant HaCaT cells was found to be more potent than known antioxidants, e.g., vitamin C and N~acetyl-L-cysteine. These results indicate that kojic Acid is a potential inhibitor of NF-$\kappa$B activation in human keratinocytes, and suggest the hypothesis that NF-$\kappa$B activation may be involved in kojic Acid induced anti-melanogenic effect.

• 한국세라믹학회지
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• 제40권11호
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• pp.1073-1077
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• 2003

Sn $O_2$ 가스센서는 낮은 농도의 가연성 가스 및 유독 가스를 표면 저항의 변화로부터 탐지할 수 있으나, 가스 선택성이 부족하다는 단점을 가지고 있다. 이러한 단점을 보완하기 위해서는 가스반응기구의 규명과 같은 기초이론 연구와 함께 선택성이 우수한 센서재료의 개발 및 적절한 신호처리방법의 적용이 필요하다. 본 논문에서는 Sn $O_2$ 표면에서 일어나는 에탄올 (C$_2$ $H_{5}$OH)과 아세토니트릴($CH_3$CN)의 촉매산화반응을 가스크로마토그래피 분석을 통해 확인하였다. PdCl$_2$가 첨가된 Sn $O_2$ 센서는 에탄올과 아세토니트릴에 대하여 높은 감도를 보였고, 반면에 La$_2$ $O_3$가 첨가된 Sn $O_2$ 센서는 에탄올에 대해서는 높은 감도를, 그리고 아세토니트릴에 대해서는 낮은 감도를 보였다. 이들 두 센서재료 개발 및 패턴인식기법적용을 통하여 아세토니트릴에 대한 선택성을 크게 증가시킬 수 있었다. 아세토니트릴에 대한 최소 탐지농도는, 공기 중에서는 15 ppm이었고, 다른 방해가스와 함께 존재할 경우에는 20 ppm에서 100 ppm 정도로 나타났다.