• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3279-3284
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• 2012

Poly(benzimidazole-co-benzoxazole)s (PBI-co-PBO) are synthesized by polycondensation reaction with 3,3'-diaminobenzidine, terephthalic acid and 3,3'-dihydroxybenzidine or 4,6-diaminoresorcinol in polyphosphoric acid (PPA). All polymer membranes are prepared by the direct casting method (in-situ fabrication). The introduction of benzoxazole units (BO units) into a polymer backbone lowers the basic property and $H_3PO_4$ doping level of the copolymer membranes, resulting in the improvement of mechanical strength. The proton conductivity of $H_3PO_4$ doped PBI-co-PBO membranes decrease as a result of adding amounts of BO units. The maximum tensile strength reaches 4.1 MPa with a 10% molar ratio of BO units in the copolymer. As a result, the $H_3PO_4$ doped PBI-co-PBO membranes could be utilized as alternative proton exchange membranes in high temperature polymer electrolyte fuel cells.

• 한국해양공학회지
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• 제31권3호
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• pp.241-247
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• 2017

Plywood, which is created by bonding an odd number of thin veneers perpendicular to the grain orientation of an adjacent layer, was developed to supplement the weak points such as contraction and expansion of conventional wood materials. With structural merits such as strength, durability, and good absorption against impact loads, plywood has been adopted as a structural material in the insulation system of a membrane type liquefied natural gas (LNG) carrier. In the present study, as an attempt to resolve recent failure problems with plywood in an LNG insulation system, conventional PF (phenolic-formaldehyde) resin plywood and its alternative MUF (melamine-urea-formaldehyde) resin bonded plywood were investigated by performing material bending tests at ambient ($20^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures to understand the resin and grain effects on the mechanical behavior of the plywood. In addition, the failure characteristics of the plywood were investigated with regard to the grain orientation and testing temperature.

• 한국가금학회:학술대회논문집
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• 한국가금학회 2006년도 제23차 정기총회 및 학술발표회
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• pp.43-58
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• 2006

As a bioreactor, bird has proved to be most efficient system for producing useful therapeutic proteins. More than half of the egg white protein content derives from the ovalbumin gene with four other proteins(lysozyme, ovomucoid, ovomucin and conalbumin) present at levels of 50 milligrams or greater. And the naturally sterile egg also contains egg white protein at high concentration allowing for a long shelf life of recombinant protein without loss in activity. In spite of these advantages, transgenic procedures for the bird have lagged far behind because of its complex process of fertilized egg and developmental differences. Recently, a system to transplant mouse testis cells from a fertile donor male to the seminiferous tubules of an infertile recipient male has been developed. Spermatogenesis is generated from transplanted cells, and recipients are capable of transmitting the donor haplotype to progeny. After transplantation, primitive donor spermatogonia migrate to the basement membrane of recipient seminiferous tubules and begin proliferating. Eventually, these cells establish stable colonies with a characteristic appearance, which expands and produces differentiating germ cells, including mature spermatozoa. Thus, the transplanted cells self-renew and produce progeny that differentiate into fully functional spermatozoa. In this study, to develop an alternative system of germline chimera production that operates via the testes rather than through developing embryos, the spermatogonial stem cell techniques were applied. This system consisted of isolation and in vitro-culture of chicken testicular cells, transfer of in vitro-maintained cells into heterologous testes, production of germline chimeras and confirmation of germline transmission for evaluating production of heterologous, functional spermatozoa.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.803-811
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• 2014

Concerns over drug-resistant bacteria have stimulated interest in developing alternative methods to control bacterial infections. Endolysin, a phage-encoded enzyme that breaks down bacterial peptidoglycan at the terminal stage of the phage reproduction cycle, is reported to be effective for the control of bacterial pathogenic bacteria. Bioinformatic analysis of the SPN9CC bacteriophage genome revealed a gene that encodes an endolysin with a domain structure similar to those of the endolysins produced by the P1 and P22 coliphages. The SPN9CC endolysin was purified with a C-terminal oligo-histidine tag. The endolysin was relatively stable and active over a broad temperature range (from $24^{\circ}C$ to $65^{\circ}C$). It showed maximal activity at $50^{\circ}C$, and its optimum pH range was from pH 7.5 to 8.5. The SPN9CC endolysin showed antimicrobial activity against only gram-negative bacteria and functioned by cutting the glycosidic bond of peptidoglycan. Interestingly, the SPN9CC endolysin could lyse intact gram-negative bacteria in the absence of EDTA as an outer membrane permeabilizer. The exogenous lytic activity of the SPN9CC endolysin makes it a potential therapeutic agent against gram-negative bacteria.

• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.343-352
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• 2015

H9 is an ethanol extract prepared from nine traditional/medicinal herbs. This study was focused on the anticancer effect of H9 in non-small-cell lung cancer cells. The effects of H9 on cell viability, apoptosis, mitochondrial membrane potential (MMP; ${\Delta}\psi_{m}$), and apoptosisrelated protein expression were investigated in A549 human lung cancer cells. In this study, H9-induced apoptosis was confirmed by propidium iodide staining, expression levels of mRNA were determined by reverse transcriptase polymerase chain reaction, protein expression levels were checked by western blot analysis, and MMP (${\Delta}\psi_{m}$) was measured by JC-1 staining. Our results indicated that H9 decreased the viability of A549 cells and induced cell morphological changes in a dose-dependent manner. H9 also altered expression levels of molecules involved in the intrinsic signaling pathway. H9 inhibited Bcl-xL expression, whereas Bax expression was enhanced and cytochrome C was released. Furthermore, H9 treatment led to the activation of caspase-3/caspase-9 and proteolytic cleavage of poly(ADP-ribose) polymerase; the MMP was collapsed by H9. However, the expression levels of extrinsic pathway molecules such as Fas/FasL, TRAIL/TRAIL-R, DR5, and Fas-associated death receptor were downregulated by H9. These results indicated that H9 inhibited proliferation and induced apoptosis by activating intrinsic pathways but not extrinsic pathways in human lung cancer cells. Our results suggest that H9 can be used as an alternative remedy for human non-small-cell lung cancer.

• 기본간호학회지
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• 제16권2호
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• pp.162-170
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• 2009

Purpose: To verify the usability of tympanic temperature measurement for adults, a comparison of tympanic and axillary temperatures was done. Method: The study was conducted during October 2008, and participants were 110 female nursing students. Axillary temperatures were taken with glass mercury thermometers for 5, 7 and 10 minutes. Tympanic temperatures were taken with Infrared Thermometer IRT 4520 on both ears, twice at a 5-second interval. The data were analyzed using the SPSS 12.0 program. Results: In the 1st measurement, the mean for right tympanic temperatures ($0.06^{\circ}C$) and for left ($0.03^{\circ}C$) were significantly higher than the 2nd. A comparison of mean temperatures for right and left, showed that the mean for the left side on the 1st measurement was significantly higher ($0.01^{\circ}C$) than the right. Also the temperature on left side in the 2nd measurement was higher ($0.04^{\circ}C$) than the right 2nd, but not significantly higher. The mean temperature for right and left tympanic on 1 st and 2nd measurements were significantly higher than axilla for 5 minutes ($0.58^{\circ}C$), for 7 minutes ($0.52^{\circ}C$), and for 10 minutes ($0.43^{\circ}C$). The tympanic temperature was the most closely correlated with the axillary temperature at 10 minutes. Conclusion: Findings indicate that measurement of tympanic temperature is a useful alternative to axillary temperature taken for 10 minutes.

• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.300-308
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• 2009

In a pursuit of the development of alternative mobile power sources with a high energy density, a planar and air-breathing PEMFCs with a new type of hydrogen cartridge which uses onsite $H_2$ generated from sodium borohydride ($NaBH_4$) hydrolysis have been investigated for use in advanced power systems. Two types of $H_2$ generation through $NaBH_4$ hydrolysis are available: (1) using organic acids such as sulphuric acid, malic acid, and sodium hydrogen carbonate in aqueous solution with solid $NaBH_4$ and (2) using solid selected catalysts such as Pt, Ru, CoB into the stabilized alkaline $NaBH_4$ solution. It might therefore be relevant at this stage to evaluate the relative competitiveness of the two methods mentioned above. The effects of flow rate of stabilized $NaBH_4$ solution, MEA (Membrane Electrode Assembly) improvement, and type and flow control of the catalytic acidic solution have been studied and the cell performances of the planar, air-breathing PEMFCs using $NaBH_4$ has been measured from aspects of power density, fuel efficiency, energy density, and fast response of cell. In our experiments, planar, air-breathing PEMFCs using $NaBH_4$ achieved to maximum power density of 128mW/$cm^2$ at 0.7V and energy efficiency of 46% and has many advantages such as low operating temperature, sustained operation at a high power density, compactness, the potential for low cost and volume, long stack life, fast star-up and suitability for discontinuous operation.

• 한국지반공학회논문집
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• 제19권6호
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• pp.335-342
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• 2003

엄밀한 변형해석을 위해서는 전체변형률 범위에서 신뢰성 있는 변형특성 평가가 가능한 현장시험 기법이 개발되어야 한다. 공내재하시험은 현장지반의 변형률 크기에 따른 전단탄성계수를 직접 평가할 수 있는 유일한 시험기법이다. 본 연구에서는 $10^{-5}$% ∼20%의 전체변형률 범위에 대하여 적용 가능한 공동변형 측정방법을 고안하였다. 개발된 장비의 순응성 검증을 위하여 검증토조에 대한 시험과 현장시험을 수행하였다. 개발된 장비는 $5\times 10^{-2}$% 이상의 변형률 범위에서 신뢰성 있는 전단탄성계수 측정이 가능하였다. 미소한 공동변형을 측정하는데 발생하는 주요 오차의 원인은 공동변형 측정 시스템 자체보다는 측정봉과 멤브레인 사이에서 역재하-재재하 과정에 발생하는 마찰인 것으로 판단된다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권4호
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• pp.326-329
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• 2002

저자들은 위축된 치조골과 외상 또는 종양으로 상실된 치조골의 재건을 위하여 수직적 치조골 신장술을 이용하여 104명의 환자에서 평균 10.2 mm의 치조골을 신장시킬 수 있었으며, 양호하게 재건된 치조골에 치과 임플란트를 식립함으로서 기능적, 심미적으로 좋은 결과를 얻을 수 있었다. 치조골 신장술은 기존의 치조골 수복술들을 대체할 수 있는 안전하고 효과적인 방법으로 생각된다.

• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.39-46
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• 2008

The end plates of fuel cell assemblies are used to fasten the inner stacks, reduce the contact pressure, and provide a seal between Membrane-Electrode Assemblies (MEAs). They therefore require sufficient mechanical strength to withstand the tightening pressure, light weight to obtain high energy densities, and stable chemical/electrochemical properties, as well as provide electrical insulation. The design criteria for end plates can be divided into three parts: the material, connecting method, and shape. In the past, end plates were made from metals such as aluminum, titanium, and stainless steel alloys, but due to corrosion problems, thermal losses, and their excessive weight, alternative materials such as plastics have been considered. Composite materials consisting of combinations of two or more materials have also been proposed for end plates to enhance their mechanical strength. Tie-rods have been traditionally used to connect end plates, but since the number of connecting parts has increased, resulting in assembly difficulties, new types of connectors have been contemplated. Ideas such as adding reinforcement or flat plates, or using bands or boxes to replace tie-rods have been proposed. Typical end plates are rectangular or cylindrical solid plates. To minimize the weight and provide a uniform pressure distribution, new concepts such as ribbed-, bomb-, or bow-shaped plates have been considered. Even though end plates were not an issue in fuel cell system designs in the past, they now provide a great challenge for designers. Changes in the materials, connecting methods, and shapes of an end plate allow us to achieve lighter, stronger end plates, resulting in more efficient fuel cell systems.