• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.33-36
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• 2008

The transient behavior of a passive air breathing direct methanol fuel cell (DMFC) operated on vapor-feeding mode is studied in this paper. It generally takes 30 minutes after starting for the cell response to come to its steady-state and the response is sometimes unstable. A mathematical dynamic one-dimensional model for simulating transient response of the DMFC is presented. In this model a DMFC is decomposed into its subsystems using lumped model and divided into five layers, namely the anodic diffusion layer, the anodic catalyst layer, the proton exchange membrane (PEM), the cathodic catalyst layer and the cathodic diffusion layer. All layers are considered to have finite thickness, and within every one of them a set of differential-algebraic governing equations are given to represent multi-components mass balance, such as methanol, water, oxygen and carbon dioxide, charge balance, the electrochemical reaction and mass transport phenomena. A one-dimensional, isothermal and mass transport model is developed that captures the coupling between water generation and transport, oxygen consumption and natural convection. The single cell is supplied by pure methanol vapor from a methanol reservoir at the anode, and the oxygen is supplied via natural air-breathing at the cathode. The water is not supplied from external source because the cell uses the water created at the cathode using water back diffusion through nafion membrane. As a result of simulation strong effects of water transport were found out. The model analysis provides several conclusions. The performance drop after peak point is caused by insufficiency of water at the anode. The excess water at the cathode makes performance recovery impossible. The undesired crossover of the reactant methanol through the PEM causes overpotential at the cathode and limits the feeding methanol concentration.

• 대한한방내과학회지
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• 제39권4호
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• pp.772-783
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• 2018

The aims of this study were to use the Rydoraku test, electrogastrography, and enterotachography to examine the presence of familial gastric dysmotility among monozygotic twins and their mothers; to determine the relationship between the symptoms and the indexes of the Rydoraku test, electrogastrography, and enterotachography; and to observe the therapeutic reaction for each differential treatment between twins with familial gastric dysmotility. The same herbal medication (Banhasasim-tang extract three times/day and Sojuckkunbi-tang extract three times/day) was given to each twin, but the younger twin also underwent manual acupuncture on the CV 10, 12, and 13 points of the abdominal wall and electrical stimulation of both ST 36 points of the lower leg 2-3 times per week. Evaluation of the therapeutic effect was followed after six weeks. The presence of familial gastric dysmotility was shown in the autonomic nerve system and gastric muscle and was thought to be a common pathophysiology induced by genetic co-ownership. Only the younger twin showed any marked relief of the dyspeptic symptoms associated with improvement of pyloric sphincter function, which was induced by acupuncture treatment. The Rydoraku test, electrogastrography, and enterotachography results showed the presence of familial gastric dysmotility. Although Korean traditional medicine had no effect on the familiar gastric dysmotility associated with genetic influences, the acupuncture treatment had a beneficial effect on the secondary disorder of pyloric sphincter function, which is associated with the relief of dyspeptic symptoms.

• Parasites, Hosts and Diseases
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• 제51권6호
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• pp.763-766
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• 2013

A synthetic peptide was prepared based on the antigenic region of Paragonimus westermani pre-procathepsin L, and its applicability for immunodiagnosis for human paragonimiasis (due to Paragonimus heterotremus) was tested using an ELISA to detect IgG4 antibodies in the sera of patients. Sera from other helminthiases, tuberculosis, and healthy volunteers were used as the references. This peptide-based assay system gave sensitivity, specificity, accuracy, and positive and negative predictive values of 100%, 94.6%, 96.2%, 100%, and 88.9%, respectively. Cross reactivity was frequently seen against the sera of fascioliasis (75%) and hookworm infections (50%). Since differential diagnosis between paragonimiasis and fascioliasis can be easily done by clinical presentation and fascioliasis serology, this cross reaction is not a serious problem. Sera from patients with other parasitoses (0-25%) rarely responded to this synthetic antigen. This synthetic peptide antigen seems to be useful for development of a standardized diagnostic system for paragonimiasis.

• 한국염색가공학회지
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• 제8권2호
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• pp.1-7
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• 1996

Thermotropic liquid-crystalline polyurethanes were synthesized by the polyaddition reaction of such para-substiuted diisocyanate monomer as 1,4-phenylene diisocyanate(1,4-PDI) and 2,5-tolylene diisocyanate(2,5-TDI), with 4,4'-bis($\omega$-hydroxyalkoxy)biphenyls(BPm: $HOC_{m}OC_{6}H_{4}C_{6}H_{4}OC_{m}H_{2m}OH$; m is the carbon number of the hydroxyalkoxy group). These polyurethanes have mesogenic biphenyl units in the main chain. Properties of polymers were studied by differential scanning calorimetry, wide-angle X-ray scattering, thermogravimetic analysis, polarizing microscopy, and infraed spectroscopy. DSC thermograms for these polymers exhibited two endothermic peaks corresponding to phase transitions of melting and isotropization. Mesomorphic behavior of the polyurethanes were also observed under the polarizing microscope. For example, polyurethane 2,5-YDI/BP5 with [$\theta$]=0.44 prepared from 2,5-TDI and BP5 exhibited a liquid crystalline phase from 194 to 205$^{\circ}C$. Infrared spectrum study indicated that the hydrogen bonding between urethane linkages affected the mesomorphism. The thermostabilities of polyurethanes 2,5-TDI/BP5 and 1,4-PDI/BP5 were measured at a heating rate of 1$0^{\circ}C$/min in air. The temperatures of 5% weight loss for 2,5-TDI/BP5 and 1,4-PDI/BP5 were 297 and 334$^{\circ}C$, respectively.

• 폴리머
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• 제34권6호
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• pp.491-494
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• 2010

무유화 에멀젼 공중합법을 이용하여 180~200 nm의 지름을 가지는 단분산성 폴리(스티렌/디비닐벤젠/비닐 아세테이트) [poly(ST-co-DVB-co-VAc)] 고분자 나노입자를 합성하였으며, 제조된 단분산성 고분자 나노입자의 표면을 비누화반응을 통하여 개질하여 단분산성 폴리(스티렌/디비닐벤젠/비닐알코올) [poly(ST-co-DVB-co-VA)] 나노입자를 제조하였다. 합성된 입자를 반응염료와 반응시켜 적색과 청색 단분산성 폴리(스티렌/디비닐벤젠/비닐알코올) 나노입자를 제조하였으며, 입자의 형태, 분산성 및 표면전하를 전자현미경, 시차열분석기, UV/Vis 흡광기 및 제타 전하 측정장치를 이용하여 규명하였다.

• 한국진공학회지
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• 제2권4호
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• pp.439-454
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• 1993

The phase sequence of codeposited Co-Si alloy and Co/si multilayer thin film was investigated by differential scanning calormetry(DSC) and X-ray diffraction (XRD) analysis, The phase sequence in codeposition and codeposited amorphous Co-Si alloy thin film were CoSilongrightarrow Co2Si and those in Co/Si multilayer thin film were CoSilongrightarrowCo2Silongrightarrow and CoSilongrightarrowCo2Si longrightarrowCoSilongrightarrowCoSi2 with the atomic concentration ration of Co to Si layer being 2:1 and 1:2 respectively. The observed phase sequence was analyzed by the effectvie heat of formatin . The phase determining factor (PDF) considering structural facotr in addition to the effectvie heat of formation was used to explain the difference in the first crystalline phase between codeposition, codeposited amorphous Co-Si alloy thin film and Co/Si multilayer thin film. The crystallinity of Co-silicide deposited by multitarget bias cosputter deposition (MBCD) wasinvestigated as a funcion of deposition temperature and substrate bias voltage by transmission electron microscopy (TEM) and epitaxial CoSi2 layer was grown at $200^{\circ}C$ . Parameters, Ear, $\alpha$(As), were calculate dto quantitatively explain the low temperature epitaxial grpwth of CoSi2 layer. The phase sequence and crystallinity had a stronger dependence on the substrate bias voltage than on the deposition temperature due to the collisional daxcade mixing, in-situ cleannin g, and increase in the number of nucleation sites by ion bombardment of growing surface.

• 대한토목학회논문집
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• 제14권3호
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• pp.635-644
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• 1994

혐기성 소화에 비해 낮은 시설비 및 공정의 안정성 등의 장점으로 중소규모 하수처리장의 슬리지 처리에 적합한 호기성 소화의 상징액내 영양염류 농도를 예측하기 위하여, 본 연구에서는 질소 및 인의 거동 관찰로 주요반응을 규정하고 물질수지를 고려해서 연립미분방정식 형태로 수학적 모형을 수립하였다. 하수처리장의 폐활성슬러지를 시료로 하여 초기 고형물 농도 수준을 다르게 한 회분식 호기성 소화조를 온도 $20^{\circ}C$, pH $7{\pm}0.5$의 조건에서 운영하였고, 반응계수 추정을 위하여 비선형 회귀분석을 실시하였다. 수립된 모형은, Biomass-N, 용존 유기질소, $NH_4{^-}$-N, $NO_x{^-}$-N과 Biomass-N, 용존 유기인, $PO_4{^-}$-P와 같은 영양염류의 거동 예측이 가능하였다. 모의실험으로 고형상의 영양염류보다 용존상 영양염류가, 질소보다는 인이 상징액에 미치는 영향이 크다는 것을 보였다.

• 대한기계학회논문집B
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• 제23권9호
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• pp.1151-1162
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• 1999

The effects of radial heat and $H_2O$ diffusion on the evolution of silica particles in coflow diffusion flames have been studied experimentally. The evolution of silica aggregate particles in coflow diffusion flames has been measured experimentally using light scattering and thermophoretic sampling techniques. The measurements of scattering cross section from $90^{\circ}$ light scattering have been utilized to calculate the aggregate number density and volume fraction using with combination of measuring the particle size and morphology through the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh-Debye-Gans and Mie theory for fractal aggregates and spherical particles, respectively. Flame temperatures and volumetric differential scattering cross sections have been measured for different flame conditions such as inert gas species, $H_2$ flow rates, and burner injection configurations to examine the relation between the formation of particles and radial $H_2O$ diffusion. The comparisons of oxidation and flame hydrolysis have also been made for various $H_2$ flow rates using $N_2$ or $O_2$ as a carrier gas. Results indicate that the role of oxidation becomes dominant as both carrier gas($O_2$) and $H_2$ flow rates increases since the radial heat diffusion precedes $H_2O$ diffusion in coflow flames used in this study. The effect of carrier gas flow rates on the evolution of silica particles have also been studied. When using $N_2$ as a carrier gas, the particle volume fraction has a maximum at a certain carrier gas flow rate and as the flow rate is further increased, the hydrolysis reaction Is delayed and the spherical particles finally evolves into fractal aggregates due to decreased flame temperature and residence time.

• Parasites, Hosts and Diseases
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• 제45권1호
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• pp.69-74
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• 2007

Trichostrongylus eggs observed in cellophane-thick smears are difficult, in practice, to distinguish from hookworm eggs. In order to overcome these limitations, a molecular approach was conducted. A Trichostrongylus colubriformis adult worm was obtained from a human in Laos, which was identified morphologically. ITS-1 sequence of this worm was determined, and found to be most similar with that of T. colubriformis among the Trichostrongylus spp. reported so far. Then, this sequence was compared with those of human hookworm species, Ancylostoma duodenale and Necator americanus, and species-specific oligonucleotide primers were designed. Polymerase chain reaction(PCR) using these primers evidenced specifically amplified PCR products of Trichostrongylus sp., A. duodenale and N. americanus from the eggs of each(520 bp, 690 bp, and 870 bp, respectively). A species-specific PCR technique can be developed in order to study the epidemiology of Trichostrongylus spp. and hookworms in endemic areas.

• 대한세포병리학회지
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• 제15권2호
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• pp.81-85
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• 2004

Postmenopausal squamous atypia (PSA) is a phenomenon characterized by cellular alterations mimicking condyloma in the uterine cervix of postmenopausal women. It is not associated with human papillomavirus (HPV) infection. The aim of this study is to correlate findings with HPV infection and the cytohistologic findings of PSA. Eighty-three smears from postmenopausal women, initially interpreted as ASCUS and low-grade squamous intraepithelial lesions(LSIL), were reviewed according to the criteria of PSA. Fifty-eight cases were subsequently reclassified as PSA. Forty cases categorized as PSA were available for HPV-DNA detection by a nested polymerase chain reaction. Eight of these 40 cases(20%) showed biopsy-proven LSIL lesions. The HPV-DNA was detected in 42.5%(17/40), compared to 25%(5/20) of control cases. The HPV-DNA detection rate of biopsy-proven LSIL was 62.5%(5/8). It has been concluded that cytologic differential diagnosis of PSA from LSIL is difficult due to because of poor histologic and viral correlation.