• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.201-209
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• 2013

The spread and expansion of pests and pathogens due to climate change have caused considerable reduction of rice yield in agricultural landscapes. This study was conducted to quantitatively analyze the spread of rice pathogens carried by insect pests on spatial network in South Korea using graph-theoretic methods. We identified the connectivity "backbone" of pathogen spread network among the cities along the coastal area of West Sea. In addition, we graphically represented 1) the core areas that can cause local and regional outbreaks of pathogens; and 2) the areas that act as bottlenecks in the spread of pathogen which can link the core areas. Especially, the cities in the coastal areas of West Sea that have the high density of rice crops, represented a low spread resistance to pathogen infection. These results may suggest insights into planning the integrated pest management possibly through regional collaboration.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.89-89
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• 2001

종이는 목재섬유와 물의 현탁액을 스크련을 통해 균일하게 분산시킨 판상섬유 제품 으로서 가격이 저렴하고, 열, 전기절연성, 필터기능, 난연성 및 폐기성이 우수하여 다양한 분 야에서 활용되고 있다. 특히 최근에는 종이의 고부가가치화, 차별화를 위하여 내열성, 전기 절연성, 내수성, 기계적 특성, 내약품성, 생체적응성을 지닌 다양한 기능지가 개발되어 식품, 전기, 전자, 건축, 화학, 의료 관련 산업에 있어서 주요 재료로 이용되고 있다. 특히 전기, 전 자산업 발전과 더불어 전기절연성이 우수한 종이의 역할과 수요는 크게 증대되고 있으며 산 업발전의 핵심적인 제품으로서 자리매김을 하고 있다. 하지만 국내의 경우 전기절연지와 관 련된 제품 및 생산기술 부족으로 전량을 수입에 의존하고 있는 실정이며, 그 수입량은 앞으 로 전기 및 전자 산업의 발전으로 인해 더욱 증가할 것으로 예상된다. 이러한 수입의존성을 극복하기 위해서는 전기절연지와 관련된 제품개발 및 생산기술에 관한 연구가 시급히 요청 되고 있다. 이러한 기술의 국산화는 수입 대체 효과 뿐만 아니라 관련 산업의 발전에도 기 여할 수 있을 것으로 예상되며 수출산업으로 성장할 수 있을 것으로 예상된다. 종이의 전기적 성질은 유전상수, 유전손실율과 같은 유전적 특성과 전기저항, 절연 파괴강도의 기계적 특성으로 구분할 수 있다. 종이의 전기적 성질 가운데 유전율은 전기장 에 대한 종이의 물리화학적인 반응으로 일반적으로 종이의 밀도와 종이를 구성하는 성분의 쌍극자 모멘트에 비례하며 온도에 따라서도 변화한다. 일반적으로 온도가 상승하면 열에너 지를 얻게된 쌍극자가 전기장에 배열됨으로써 유전율이 상승하지만 온도가 유리전이점 이상 으로 높아질 경우 열적 교란에 의해서 분극 능력이 감소하게 되어 유전완화 현상이 나타난 다. 전기절연지로 사용될 종이의 절연특성을 이해하기 위해서는 사용환경에 따른 유전적 특 성 및 tan$\delta$에 관한 연구가 펼요하다. 본 연구에서는 종이의 유전특성을 개선하기 위해서 펼름형성능력이 우수한 polyvinyl alcoholCPV A)과 aery lonitrile을 이용하여 시아노에틸화한 P PYA의 표면처리에 따른 종이의 유전적 특성의 변화를 검토하였다. 그 결과 PYA에 도입된 시아노에틸기에 의해 유전율을 증가시킬 수 있음을 확인하였다. 또 본 연구에 적용된 시험 범위에서는 온도상승에 따라 유전율이 상승하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2407-2414
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• 1992

Constant temperature hot wire air flow meter for automobiles requires temperature compensation system because hot wire output signal is sensitive to ambient temperature variations as well as fluid velocity. The objectives of the present study are to design an air flow meter circuit which is capable of compensating the hot wire output signal for ambient temperature variations and to investigate the mechanism of such temperature compensation. This circuit is composed of platinum hot wire, platinum resistor, two variable resistors, a constant resistor and a DC-amplifier. In particular, by simply replacing a constant resistor in one of the bridge arms of the conventional circuit with platinum resistor and a variable resistor for the purpose of temperature compensation, the deviation of output signal with respect to ambient temperature variations between 27deg. C 70deg. C could be reduced to less than 2.5% for mass flow rate and to less than 5% for velocity respectively. The mechanism of temperature compensation against ambient temperature variations was explained by means of measuring the heat transfer coefficient with hot wire temperature variations and analyzing and analyzing conventional empirical equations qualitatively.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.8-13
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• 2010

Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe launch environments. The launch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. Especially when optical payload is accommodated, satellite structure usually adopts the optical bench consisting of composite material not only to support and secure but also to guarantee good pointing stability against extreme thermal environments. This paper deals with optical bench and support structure which shall be designed to minimize the loads transferred to optical payloads from satellite.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.4
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• pp.395-400
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• 1991

Effects of Various Chemical Substrates on Heat Resistance of Isolated EnterobTo pursue the various properties of Enterobacter sp. which may give an outbreak of food-borne disease to man, isolated from the meats and the small intestines of wild mice, and to offer the significant data in the fields of food hygiene and public health this study was carreied, 5 strains of Enterobacter sp. were isolated from the above samples. 5 strains isolated from sample sources were 1 strain (E. aerogenes) from the beeves, 2 strains (E. aerogenes, E intermedium) from the pork and 2 strains (E. aerogenes, E. cloacae) from the small intstines of wild mice. Of total isolatd 89 strains, including non-Enterobacter sp., these numbers of 5 isolates were showed as 5.6% of dection rate. On heating at temperature of $55^{\circ}C$ for 30min., these 5 stratins were generally more resisted in the 0.1M phosphate buffer when such chemical substrates as 0.1M glycine, 5% mannitol or 0.5% sorbitol was added to it whereas they were appeared weaker resistances in 0.1M phosphate buffer when 1% sodium citrate, 1% casein, 10% sodium chloride or 0.1M systein was infused into it.cter sp.

• Elastomers and Composites
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• v.46 no.3
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• pp.231-236
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• 2011

The polyacrylate/multi-walled carbon nanotube (MWNT) composites were prepared and investigated for the application as a counter electrode in solar cell. The electrical conductivity of the composites was increased with increasing MWNT content and with the thickness of the sheet. The surface resistivity value of the composite at 50 wt% loading of MWNT was 0.36 ${\Omega}$/sq. The thermal decomposition temperature of the composites was also increased with the MWNT contents, and the increase of $15^{\circ}C$ was observed at the composite of polyacrylate/MWNT (50/50, w/w). The increase of storage modulus of the composites was observed, especially at the higher temperature compared to polyacrylate. The dimensional change of polyacrylate decreased over $20^{\circ}C$, but that of the composite increased linearly with the temperature. The morphology of the composites stands for the good dispersion of MWNT into the polyacrylate matrix.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.7-13
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• 1998

The VLSI devices of submicron level trend to have a lowering of reliability because of hot carriers by two dimensional influences which are caused by short channel effects and which are not generated in a long channel devices. In order to minimize the two dimensional influences, much research has been made into various types of source/drain structures. MOS typed tunnel transistor with Schottky barrier junctions at source/drain, which has the advantages in fabrication process, downsizing and response speed, has been proposed. The experimental device was fabricated with p type silicon, and manifested the transistor action, showing the unsaturated output characteristics and the high transconductance comparing with that in field effect mode. The results of trial indicate for better performance as follows; high doped channel layer to lower the driving voltage, high resistivity substrate to reduce the leakage current from the substrate to drain.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.5
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• pp.285-289
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• 2003

This paper proposes a 10 ${\mu}{\textrm}{m}$ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and rnicrornachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation (50$0^{\circ}C$, 1 hr at $H_2O$/O$_2$) and rapid thermal oxidation (RTO) process (105$0^{\circ}C$, 2 min). This structure is mechanically stable because of thick oxide layer up to 10 ${\mu}{\textrm}{m}$ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 1 dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about - 20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.287-291
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• 1999

Dopamine agonists are commonly used in the medical treatment of prolactinomas. Bromocriptine has been the most widely used ergot derivative for two decades. Its oral administration, at a daily dose of $2.5{\sim}7.5mg$, restored normal gonadal function and normoprolactinemia in about 80% of patients. Nevertheless, a subset of patients could not achieve normal prolactin levels or resume normal gonadal function despite $15{\sim}30mg$/day bromocriptine for at least 6 months. Subsequently, these prolactinomas were consedered to be resistant to bromocriptine. The percentage of bromocriptine - resistant prolactinoma patients reported in the literature varies between 5 and 17% according to the series. Patients with bromocriptine resistance or bromocriptine intolerance have, however, been treated with other dopamine agonists, such as lysuride, pergolide, cabergoline, or quinagolide. Until cabergoline recently gained a product licence in the UK, there was no alternative dopamine agonist with a licence for this purpose. Quinagolide (CV $205{\sim}502$, Norprolac, Sandoz) is a nonergot dopamine agonist with improved selectivity for the D2 receptor, designed to retain the active pharmacophore of bromocriptine without the ergot moiety that might be responsible for side - effects. We have experienced a case of bromocriptine resistant hyperprolactinemia which was reponsive to pergolide. So we report this case with a brief review of literatures.

• Food Science of Animal Resources
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• v.22 no.2
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• pp.164-171
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• 2002

The purpose of this study was to evaluate inhibitory activity of a bacteriocin mixture from lactic acid bacteria(LAB) against foodborne pathogens. Each bacteriocin solutions were prepared by growing nine strains of bacteriocin producers in MRS broth for 18~24 h followed by centrifugation(8000$\times$g, 20 min, 4$^{\circ}C$). Bacteriocins were purified from ammonium sulfate precipitation and were resuspended in 50 mM phosphate buffer(pH 7.0). Nine bacteriocins were mixed together and then allowed to freeze at -2$0^{\circ}C$. The mixture of nine bacteriocins showed enhanced inhibitory activity compared to each of bacteriocins and inhibited the Gram negative pathogens including Escherichia coli 0157:H7, Klebsiella pneumoniae, Pseudomonas chlororaphis and Shigella sonnei. The mixture of bacteriocin solutions was significantly lower than controls when a freeze-dried bacteriocin mixture was added to frank sausage, Mozzarella cheese and pork loin. With addition of bacteriocin mixture, total mesophilic bacteria in pork loin were constant over storage period, whereas total mesophilic bacteria in Mozzarella cheese and frank sausang slightly increased. Total viable cells of control group increased during storage without bacteriocin treatment. Volatile base nitrogen content of pork loin during storage also increased significantly without bacteriocin treatment. The bacteriocin mixture was capable of inhibiting pathogenic and spoilage microorganisms and extending the shelf-life of cheese and meat products during storage.