• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.172-175
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• 2009

A bipolar plate is an important component in a fuel cell in the sense of cost and weight. This study aimed at developing highly conductive, lightweight, and low cost bipolar plates. Hybrid carbons filled poly(phenylene sulfide)(PPS) composite bipolar plates were prepared by using the compression molding technique. Various types and amounts of conducting carbon fillers such as graphite, carbon black, carbon fibers, and carbon nanotubes (CNTs) were adopted for the composites. Electrical conductivity and mechanical properties of the composites were measured in order to investigate effects of each components of fillers. When the graphite is only used as a conducting filler, the electrical conductivity of the composites increases with increasing the content, but the flexural strength decreases dramatically. However, for CNTs and carbon fibers, the flexural strength initially increases and then decreases with increasing the amount of the conducting fillers. The amount of graphite corresponding to the peak of flexural strength was moved to lower content with increasing the amount of CNTs or carbon fiber. When hybrid conducting fillers such as fibrous and particulate fillers were used, the synergy effect in mechanical and electrical properties was observed.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.39-46
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• 2006

The fuel cell is one of promising environment-friendly energy sources for the next generation. The bipolar plate is a major component of the PEM fuel cell stack, which takes a large portion of stack cost. In this study, as alternative materials for bipolar plate of PEM fuel cells, graphite composites were fabricated by compression molding. Graphite particles mixed with epoxy resin were used as the main substance to provide electric conductivity To achieve desired electrical properties, specimens made with different mixing ratio, processing pressure and temperature were tested. To increase mechanical strength, one or two layers of woven carbon fabric were added to the graphite and resin composite. Thus, the composite material was consisted of three phases: graphite particles, carbon fabric, and epoxy resin. By increasing mixing ratio of graphite, fabricated pressure and process temperature, the electric conductivity of the composite was improved. The results of tensile test showed that the tensile strength of the two-phase graphite composite was about 4MPa, and that of three-phase composite was increased to 57MPa. As surface properties, contact an91e and surface roughness were tested. Graphite composites showed contact angles higher than $90^{\circ}$, which mean low surface energy. The average surface roughness of the composite specimens was $0.96{\mu}m$.

• 한국수소및신에너지학회논문집
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• 제23권2호
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• pp.134-142
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• 2012

A bipolar plate is a major component of a fuel cell stack, which occupies 50~60% of the total weight and over 50% of the total cost of a typical fuel cell stack. In this study, a composite bipolar plate is designed and fabricated to develop a compact and light-weight direct methanol fuel cell (DMFC) stack for a small-scale Unmanned Aerial Vehicle (UAV) application. The composite bipolar plates for DMFCs are prepared by a compression molding method using resole type phenol resin as a binder and natural graphite and carbon black as a conductor filler and tested in terms of electrical conductivity, mechanical strength and hydrogen permeability. The flexural strength of 63 MPa and the in-plane electrical conductivities of 191 S $cm^{-1}$ are achieved under the optimum bipolar plate composition of phenol : 18%; natural graphite : 82%; carbon black : 3%, indicating that the composite bipolar plates exhibit sufficient mechanical strength, electrical conductivity and hydrogen permeability to be applied in a DMFC stack. A DMFC with the composite bipolar plate is tested and shows a similar cell performance with a conventional DMFC with graphite-based bipolar plate.

• 대한세포병리학회지
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• 제10권2호
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• pp.163-167
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• 1999

Primary small cell carcinoma of the salivary gland is a rare neoplasm that accounts for approximately 1.8% of all primary major salivary gland malignancies. Because of its rarify, it is difficult to diagnose small cell carcinoma of the parotid gland by fine needle aspiration cytology(FNAC). We experienced a case of primary small cell carcinoma of the parotid gland in a 72-year-old woman who presented with two palpable masses of the left infraauricular and ocular legions of two to three month's duration, respectively. Aspirate smears from the left infraauricular area were highly cellular on necrotic and lymphocytic background and showed individually dispersed cells or three-dimensional clusters of small cells. The tumor cells were round to oval with a very high nucleocytoplasmic ratio. Nuclei were about two times the size of lymphocytes and had uniformly dispersed but hyperchromatic to pyknotic chromatin. Nucleoli were occasionally visible but were generally inconspicuous. Numerous mitotic figures were detected. The clusters of these small tumor cells exhibited angular nuclear molding, irregular nuclear outlines, and occasionally rosette like arrangement. The tumor was confirmed by histology and immunohistochemistry.

• 대한기계학회논문집A
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• 제29권5호
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• pp.647-654
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• 2005

This research Proposes a Process design of injection molded microcellular plastic gears for enhancing the fatigue strength/durability and accuracy of the gears applying thermodynamic instability to microcellular foaming process. To develop the injection molded plastic gears by way of microceliular process, it is absolutely necessary the following two process design. The first is microcellular forming process for enhancing the strength/durability of plastic gears. To be microcellular process succeeded, based on the microcellular principle, mechanical apparatus is designed where nucleation and cell growth are to be generated renewably. The second is the counter pressure process which is mainly fur improving the tooth surface roughness and the accuracy of microcellular gears. For the former process, screw, nozzle and gas equipment are newly designed, and for the latter, counter pressure by nitrogen gas is intentionally brought about into mold cavity when injecting plastic gears. Based on the proposed process design, using gear mold, experiments of injection molding show that, in internal space of plastic gears, microcellular nuclear cells less than 5 lim in diameter have been generated homogeneously via electron microscope photos.

• Korean Chemical Engineering Research
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• 제54권2호
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• pp.223-228
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• 2016

본 논문은 PDMS을 기반으로 한 미세접촉인쇄법을 사용하여 보다 효율적으로 지방세포를 선택적으로 배양접시에 부착시켰으며 패터닝 된 배양접시에서 지방세포가 빠르게 지방분화를 가능하게 하였다. PDMS을 이용한 선택적 표면 처리 방법은 기존의 세포칩 제작과 달리 소량의 유기용매사용, 저가의 장비 사용, 또한 효율적으로 특정 지역 안에서 지방세포를 고정화하고 성장시킬 수 있으며 이를 통해 지방세포의 생리학적 상태를 손쉽게 관찰할 수 있는 분석 기술로 활용된다. 이렇게 구성된 지방세포칩 위에 대표적인 비만 억제제 약물인 Orlistat을 $0.2{\mu}M{\sim}5.0{\mu}M$ 농도로 처리하였을 때 대조군에 비하여 최대 26.5%의 억제 효과가 나타남을 확인하였다. 따라서, 본 논문에서 제안하는 방법을 통하여 다양한 비만 억제제 약물 탐색을 위한 세포칩으로 활용이 가능할 것으로 기대된다.

• 대한세포병리학회지
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• 제17권2호
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• pp.120-125
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• 2006

Distinguishing small cell carcinoma from other lung malignancies is of great clinico-therapeutic significance. Small cell carcinoma is an aggressive tumor with a tendency to metastasize early. Survival time if untreated is low but this tumor is highly responsive to chemotherapy. We have occasionally experienced difficulties in differentiation between adenocarcinoma and small cell carcinoma of the lung in fine needle aspiration cytology (FNAC). The aim of this study was to investigate the possibility of distinguishing small cell carcinoma from adenocarcinoma of the lung in FNAC. We evaluated cytomorphological features of FNAC specimens from 62 small cell carcinomas and 57 adenocarcinomas from the lung that were confirmed by biopsy and/or immunohistochemistry on cell block. Cytomorphological details of the two tumors were compared. Nuclear smearing and nearly absent cytoplasm were the most distinct findings in small cell carcinoma compared to adenocarcinoma (p<0.05). Necrotic background, architecture and chromatin pattern, nuclear molding and nucleoli were significantly different (p<0.05). Nuclear size, nuclear membrane nature and nuclear size variation however were not helpful in distinguishing the two tumors. Combining several features described above, small cell carcinoma can be properly differentiated from adenocarcinoma on FNAC. FNAC is proposed as a diagnostic tool of small cell carcinoma of the lung in the case of inaccessibility to biopsy, and so may allow the proper therapeutic strategies to be determined in such cases

• 한국분말재료학회지
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• 제20권6호
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• pp.467-473
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• 2013

This research presents a preparation method of dental components by metal injection molding process (MIM process) using titanium scrap. About $20{\mu}m$ sized spherical titanium powders for MIM process were successfully prepared by a novel dehydrogenation and spheroidization method using in-situ radio frequency thermal plasma treatment. The effects of MIM process parameters on the mechanical and biological properties of dental components were investigated and the optimum condition was obtained. After sintering at $1250^{\circ}C$ for 1 hour in vacuum, the hardness and the tensile strength of MIMed titanium components were 289 Hv and 584 MPa, respectively. Prepared titanium dental components were not cytotoxic and they showed a good cell proliferation property.

• 한국수산과학회지
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• 제55권5호
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• pp.662-669
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• 2022

The purpose of this study is to test the effects of electrolyzed water treatment on dried-laver Pyropia sp. processing facilities to control microbial contamination. Following the progression of the process to the next step, as well as during the lapse between process operating hours, the contamination level of total viable cell counts (TVC) and total coliform (TC) of laver increased. The TVC increased during the aging step, and after the molding-drying steps were completed, it increased by approximately 2.0 log CFU (colony forming unit)/g. Freshwater used for processing in April had a TVC of 4.31 log CFU/mL, which was more polluted than 2.61 log CFU/mL of seawater. Electrolyzed water was used to treat the sponge used in the laver-molding process, which resulted in a 2 log CFU/mL decrease.The TVC of dried-laver decreased by 1 to 2 log CFU/g when electrolyzed water was applied to the process. In conclusion, application of electrolyzed water in dried-laver processing was shown to be effective in reducing the microbiological contamination of the final product.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.384-387
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• 2002

In the resin transfer molding, there are many advantages such as high volume, high performance, and low cost, The permeability is essential in the design and operation of the process, Traditionally, the determination of permeability can be divided as three methods, which are experimental measurement, analytical, and numerical prediction using the Darcy's law. In this study, the permeability in the microscopic level is first computed on the square-packing and hexagonal packing structures of the filaments inside the yarn by using CVFEM. (omitted)