• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.172-175
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• 2001

Nanophase catalyst layer for direct methanol fuel cell has been fabricated by magnetron sputtering method. Catalyst metal targets and carbon were sputtered simultaneously on the Nafion membrane surface at abnormally higher gas (Ar/He mixture) pressure than that of normal thin film processing. They could be coated as a novel structure of catalyst layer containing porous PtRu or Pt and carbon particles both in nanometer range. Membrane electrode assembly made with this layer led to a reduction of the catalyst loading. At the catalyst loading of 1.5mg $PtRu/cm^2$ for anode and 1mg $Pt/cm^2$ for cathode, it could provide $45 mW/cm^2$ in the operation at 2 M methanol, 1 Bar Air at 80"C. It is more than $30\%$ increase of the power density performance at the same level of catalyst loading by conventional method. This was realized due to the ultra fine particle sizes and a large fraction of the atoms lie on the grain boundaries of nanophase catalyst layer and they played an important role of fast catalyst reaction kinetics and more efficient fuel path. Commercialization of direct methanol fuel cell for portable electronic devices is anticipated by the further development of such design.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1520-1520
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• 2001

Food adulteration is a serious consumer fraud and a potentially dangerous practice. Regulatory authorities and food processors require a rapid, non-destructive test to accurately confirm authenticity in a range of food products and raw materials. Olive oil is prime target for adulteration either on the basis of the processing treatments used for its extraction (extra virgin vs virgin vs ordinary oil) or its geographical origin (e.g. Greek vs Italian vs Spanish). As part of an investigation into this problem, some preliminary work focused on the ability of near infrared spectroscopy to discriminate between virgin olive oils from separate regions of the Mediterranean i. e. Crete and the Peloponese. A total of 46 oils were collected: 18 originated in Crete and 28 in the Peloponese. Oils were stored in a temperature-controlled room at 2$0^{\circ}C$ prior to spectral collection at room temperature (15-18$^{\circ}C$). Samples (approximately 0.5$m\ell$) were placed in the centre of the quartz window in a camlock reflectance cell; the gold-plated baking plate was then gently placed into the cell against the glass so as to minimize the formation of air bubbles. The rear of the camlock cell was then screwed into place producing a sample thickness of 0.5mm. Spectra were recorded between 400 and 2498nm at 2nm intervals on a NIR Systems 6500 scanning monochromator. Spectral collection took place over 2-3 days. Data were analysed using both WINISI and The Unscrambler software to investigate the possibility of discriminating between the oils from Crete and the Peloponese. A number of data pre-treatments were used and discriminant models were developed using discriminant PLS (WINISI & Unscrambler) and SIMCA (Unscrambler). Despite the small number of samples involved, a satisfactory discrimination between these two oil types was achieved. Graphical examination of principal component scores for each oil type also holds out the possibility of separating oils from either Crete and the Peloponese on the basis of districts within each region. These preliminary data suggest the potential of near infrared spectroscopy to act as a screening technique for the confirmation of geographic origin of extra virgin olive oils. The sample presentation strategy adopted uses only small volumes of material and produces high quality spectra.

• Journal of the Korean Geotechnical Society
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• v.31 no.8
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• pp.17-28
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• 2015

The purpose of this study is to measure the volumetric water content of unsaturated soils during drying and wetting process by using volumetric pressure plate extractor (VPPE) incorporated with time domain reflectometry (TDR). The VPPE consists of a pressure cell, a pressure regulator, a burette system and a TDR probe. Two samples with different initial void ratios were prepared in the pressure cell, and the air pressure at the range of 0.1 kPa - 50 kPa was applied to adjust the matric suction by the pressure regulator. The burette system was used to measure the volumetric water content change of the sample according to the matric suction. In addition, the TDR probe, installed in the cell, was used to evaluate the dielectric constant from the reflected signal of the electromagnetic wave at the probe. The volumetric water content of specimen was estimated by the empirical equation between the volumetric water content and dielectric constant, which was calibrated with the Jumunjin sand. The test results show that the volumetric water content calculated by TDR probe is strongly correlated to the measured value by burette system. The hysteresis occurs during drying and wetting process. Furthermore, the degree of hysteresis reduces in the repeated process. This study suggests that TDR may be effectively used to evaluate the water content soil for the determination of water characteristic curve of unsaturated soils.

• Journal of Chest Surgery
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• v.50 no.2
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• pp.86-93
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• 2017

Background: The influence of lifestyle diseases on postoperative complications and long-term survival in patients with non-small cell lung cancer (NSCLC) is unclear. The aim of this study was to determine whether lifestyle diseases were significant risk factors of perioperative and long-term surgical outcomes in elderly patients with stage I NSCLC. Methods: Between December 1995 and November 2013, 110 patients aged 65 years or older who underwent surgical resection of stage I NSCLC at Dong-A University Hospital were retrospectively studied. We assessed the presence of the following lifestyle diseases as risk factors for postoperative complications and long-term mortality: diabetes, hypertension, chronic obstructive pulmonary disease, stroke, and ischemic heart disease. Results: The mean age of the patients was 71 years (range, 65 to 82 years). Forty-six patients (41.8%) had hypertension, making it the most common lifestyle disease, followed by diabetes (n=23, 20.9%). The in-hospital mortality rate was 0.9% (n=1). The 3-year and 5-year survival rates were 78% and 64%, respectively. Postoperative complications developed in 32 patients (29.1%), including 7 (6.4%) with prolonged air leakage, 6 (5.5%) with atrial fibrillation, 5 (4.5%) with delirium and atelectasis, and 3 (2.7%) with acute kidney injury and pneumonia. Univariate and multivariate analyses showed that the presence of a lifestyle disease was the only independent risk factor for postoperative complications. In survival analysis, univariate analysis showed that age, smoking, body mass index, extent of resection, and pathologic stage were associated with impaired survival. Multivariate analysis revealed that resection type (hazard ratio [HR], 2.20; 95% confidence interval [CI], 1.08 to 4.49; p=0.030) and pathologic stage (HR, 1.89; 95% CI, 1.02 to 3.49; p=0.043) had independent adverse impacts on survival. Conclusion: This study demonstrated that the presence of a lifestyle disease was a significant prognostic factor for postoperative complications, but not of survival, in elderly patients with stage I NSCLC. Therefore, postoperative complications may be influenced by the presence of a lifestyle disease.

• Journal of Chest Surgery
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• v.53 no.3
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• pp.93-103
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• 2020

Background: Risk assessment for pulmonary resection in patients with early-stage non-small-cell lung cancer (NSCLC) is important for minimizing postoperative morbidity. Depletion of skeletal muscle mass is closely associated with impaired nutritional status and limited physical ability. We evaluated the relationship between skeletal muscle depletion and early postoperative complications in patients with early-stage NSCLC. Methods: Patients who underwent curative lung resection between 2016 and 2018 and who were diagnosed with pathological stage I/II NSCLC were included, and their records were retrospectively analyzed. The psoas volume index (PVI, ㎤/㎥) was calculated based on computed tomography images from routine preoperative positron emission tomography-computed tomography. Early postoperative complications, defined as those occurring within 90 days of surgery, were compared between the lowest sex-specific quartile for PVI and the remaining quartiles. Results: A strong correlation was found between the volume and the cross-sectional area of the psoas muscle (R²=0.816). The overall rate of complications was 57.6% among patients with a low PVI and 32.8% among those with a normal-to-high PVI. The most common complication was prolonged air leak (low PVI, 16.9%; normal-to-high PVI, 9.6%), followed by pneumonia (low PVI, 13.6%; normal-to-high PVI, 7.9%) and recurrent pleural effusion (low PVI, 11.9%; normal-to-high PVI, 6.8%). The predictors of overall complications were low PVI (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.07-4.09; p=0.03), low hemoglobin level (OR, 0.686; 95% CI, 0.54-0.87; p=0.002), and smoking history (OR, 3.93; 95% CI, 2.03-7.58; p<0.001). Conclusion: Low PVI was associated with a higher rate of early postoperative complications in patients with early-stage NSCLC.

• Journal of Embryo Transfer
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• v.11 no.1
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• pp.15-26
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• 1996

This study was conducted to improve the in vitro maturation(JVM), in vitro fertilization (IVF) and in vitro developmental capacity of oocytes derived from slaughtered Korean native cattle. The recoverd oocytes, obtained from a local slaughter house, were used completely surrounded by at least 3 layers of cumulus cells in combination with a homogeneous cytoplasmic pigmentation. In vitro maturation was induced in TCM-199 or Ham's F-10 supplemented with LH(1O $\mu$g/rnl), FSH(35 $\mu$g/ml), estradiol-17$\beta$(1 $\mu$g/ml) at 39$^{\circ}C$ under 5% $CO_2$ in air for 24 hours. Sperm from caudal epididyrnis and previously matured cumulus-oocytes complexes were cultured for 24 hours in 100 $\mu$l droplets of fertilization media under paraffin oil. The zygotes were cultured with media(TCM-199 with bovine oviductal epithelial cells or CRlaa) for 7 to 10 days. The cleavage rate of IVM-IVF oocytes was significantly (P<0.05) higher following maturation using Ham's F-10 (59.9%) than TCM-199 (51.6%). Development to the blastocysts among cleaved embryos was not signficantly different between maturation media: Ham's F-10 (16.0%) and TCM-199(11.9%). However, the hatching rate was affected significantly (P<0.05) on rnaturation media as 62.9% in Ham's F-10, compared with 41.2% in TCM-199. The cleavage rate of IVM-IVF oocytes was significantly (P<0.05) higher following IVF using m-TALP medium (80.1%) than BO medium (51.6%). The percentage of in vitro developed blastocysts among cleaved embryos was not signficantly different between fertimization media: BO (11.7%) and m-TALP (17.6%). The cleavage and the developmental rate to the blastocysts after IVF in m-TALP or condition medium(CM) with or without oviduct epithelial cell monolayer(OECM) was similar(80.1% and 17.6% in m-TALP, 83.8% and 19.4% in M-TALP with OECM. 82.9% and 18.9% in CM, 87.6% and 16.0% in CM with OECM, respectively). The percentage of in vitro developed blastocysts among cleaved embryos was significantly (P<0.05) higher in TCM-199 medium co-cul tured with bovine oviduatal epithelial cell monolayers(35.2%) than CRlaa medium(1.9%). These results stggest that the most transferable IVF embryos could be produced from Ham's F-10, m-TALP and TCM-199 medium with bovine oviductal epithelial cell monolayers for IVM, IVF and IVC, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.195-200
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• 2020

With the growing interest in fossil fuel depletion and environmental pollution, railroad cars operating in Korea are in progress as the conversion from diesel to electric vehicles expands. The photovoltaic system, which is applied as an example of the conversion of electric vehicles, is infinite and pollution-free, and can produce energy without generating hazards such as air pollution, noise, heat, and vibration, and maintain fuel transportation and power generation facilities. There is an advantage that is rarely needed. However, the amount of electricity produced depends on the amount of solar radiation by region, and the energy density is low due to the power generation of about 25㎡/ kWp, so a large installation area is required and the installation place has limited problems. In view of these problems, many studies have been applied to fuel cells in the railway field. In particular, the plan to link the fuel cell power generation system railroad power supply system must be linked to the power supply system that supplies power to the railroad, unlike solar and wind power. Therefore, it has a close relationship with railroad cars and the linkage method can vary greatly depending on the system topology. Therefore, in this paper, we study the validity through simulation modeling related to linkage analysis according to system topology.

• Korean Journal of Bronchoesophagology
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• v.6 no.1
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• pp.29-37
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• 2000

Background and Objectives : The concentration of sulfur dioxide($SO_2$) gas in the ambient air appears increasing in the industry and urban area day by day. It was known that $SO_2$ is noxious gas. $SO_2$ can be irritating to the eyes, nose, throat, upper respiratory tract and skin. It produces sulfurous acid on contact with water and is extremely irritating to the nasopharynx and respiratory tract. Laminin is a family of extracellular matrix glycoproteins localized in the basement membrane that separates epithelial cells from the underlying stroma. The biological activities of laminin are to promote cell migration, wound healing, growth and differentiation. Meterials and Methods : The histologic changes and the expression of laminin in tracheal mucosa sacrificed at every weeks (to 7 weeks) after continued $SO_2$ exposure of 250ppm for 30 minutes a day were studied in rats. Results : Pathologic tissue was formed at the tracheal mucosa and the underlying tissue by the infiltration of monocytes and epithelium was transformed to the single cell layered epithelium above 5 weeks after exposure. At the 6 weeks after exposure, epithelial cells were partially lost and epithelial cell layer was transformed to be leaf-shaped. Submucosal tissue was transformed to be lymphatic tissue. An intense positive staining for laminin was found in apical cytoplasm and lateral surface of the normal epithelial cells and basement membrane but at the 5 and 6 weeks after exposure, laminin activity was decreased to the moderate activity. At the 7 weeks after exposure, laminin activity was decreased to the weak activity. Conclusion : Our finding suggests that $SO_2$ makes histologic damage on the tracheal mucosa and decreases immunoreactivity for laminin. Longer duration of the exposure of $SO_2$ makes more histologic damage on the tracheal mucosa and decreases immunoreactivity for laminin.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.399-422
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• 1995

The purpose of this study was to investigate a fragment of possibility of pulpotomy with the Nd-YAG laser by the observation of pulpal healing process and the fine structural changes of the fibroblasts of the remaining pulpal tissues. Class V cavities on !55 teeth from 4 adult dogs were prepared and the pulp chambers were opened with a sterilized round bur. In the control group(19 teeth), the exposed coronal pulps were excised by a sharp excarvator. After bleeding was controlled with the sterilized cotton pellets, calcium hydroxide powder was applied on the remaining pulpal tissues and the cavities were sealed with Z.O.E. In the experimental group 1 : the pulpotomy with laser-calcium hydroxide powder application group(l9 teeth), the exposed coronal pulps were excised by Nd-YAG laser(10 watts power, 2 psi water, 20 psi air) for 2 or 3 seconds and calcium hydroxide powder was applied on the remaining pulpal tissues and the cavities were sealed with Z.O.E. In the experimental group 2 : the pulpotomy with laser-no calcium hydroxide powder application group(17 teeth), after amputating the coronal pulps with Nd-YAG laser as the experimental group 1, the remaining pulpal tissues were covered with stenilized aluminum foil and the cavities were filled with Z.O.E. The animals were sacrificed at the intervals of 1, 2, 3 and 4 weeks. All the teeth were rouutinely processed and the remaining pulpal tissues were observed by the light microscope and electron microscope. The results were as follows : 1. In light microscopic findings, there was no significant difference of the inflammatory response in the remaining pulpal tissues between the control group and the experimental groups. In both of the experimental group 1 : pulpotomy with laser-calcium hydroxide powder application group and the control group, the dentin bridges were observed after 2 weeks and the structure of the dentin bridge was almost same. In the experimental group 2 : pulpotomy with laser-no calcium hydroxide powder application group, the fibrous layers instead of dentin bridge were observed on the superficial portion of the remaining pulpal tissues after 2 weeks and they were consisted with densely crowded active fibroblasts. 2. In the electronmicroscopic findings, the active fibroblasts in the experimental groups were more frequently observed than in the control group at 1 week. But active fibroblasts were found with same frequency after 2 weeks in all of the control group and the experimental groups. 3. General distortions of the cell such as loss of the cell membrane, vaculoization of the cell etc. were observed at the suberficial layer of the remaining pulpal tissues and the carbonization was found in the dentinal wall in 1 week of the experimental groups. 4. In the experimental group 2 : pulpotomy with laser-no calcium hydroxide powder application group, the activity and the density of the fibroblasts in the fibrous layer were more than those in the deep portion of the remaining pulpal tissues after 2 weeks. 5. In the control group, bacteria such as cocci and bacilli were observed frequently, but in the experimntal groups, they could not be observed.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.613-620
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• 2021

A flow channel shape of PEMFC has an influence on the internal flow uniformity. If the reactant distribution in a flow path is not uniform during operation, both catalyst deactivation and mechanical damage of membrane could occur resulting in decreasing the membrane electrode assembly (MEA) durability. Numerous studies concerning flow design have been conducted to make smooth supply and uniform distribution of reactants in fuel cells. The baffle of flow path could improve fuel cell performance through the forced convection effect. A sub-channel, as an additional air flow path, could increase the reactant concentration and reduce the mass transfer loss via a smooth water discharge. In this study, computational fluid dynamics (CFD) was used to analyze the effect of blocks and sub-channels on the current density and oxygen concentration of the fuel cell. As a result, the limit current density and oxygen concentration at a rear block increased when using blocks and sub-channels in a flow channel. In particular, the current density increased significantly when the sub-channel was placed between two blocks. Also, the sub-channel position was optimized by analyzing the oxygen concentration, and the oxygen concentration was recovered at a rear block in the fuel cell.