• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.205-211
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• 1998

Participating in a multi-disciplinary oceanography program in July 1997 in the vicinity of Tokdo, we studied the distributions of bacterial abundance and production along with those of phytoplankton and heterotrophic nanoflagellates. In the euphotic zone, chlorophyll a (chl a) concentrations ranged from 0.14 to 0.52 ${\mu}$g 1$^{-1}$. Bacterial abundance in the euphotic zone (0.12-0.21 ${\times}$ 10$^9$ cells 1$^{-1}$) in the study area was quite lower than that expected from the observed chi a concentration in the marine environment. The low bacterial abundance seemed to be due to active grazing pressure on bacteria. The fraction of primary production utilized by bacteria was also low(8-12%). Interestingly, surface water temperatures were love. at stations near islands compared to an offshore station located between Ulleungdo and Tokdo and the highest values of bacterial production and chi a were found at stations near islands, strongly indicating island mass effects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2172-2178
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• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.

• Mycobiology
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• v.47 no.4
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• pp.483-493
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• 2019

Antrodia cinnamomea is a unique medicinal fungus in Taiwan. It has been found rich in some pharmacologically active compounds for anti-cancer, hangover, and immune regulation etc. With the in-depth study of these components, it would be interesting and important to establish a molecular system for basic studies of A. cinnamomea. Thus, we would like to set up a foundation for this purpose by studying the A. cinnamomea protoplast preparation and regeneration. Firstly, we studied the optimization method of protoplast preparation of A. cinnamomea, and found various factors that may affect the yield during protoplast preparation, such as mycelial ages, pH values, and osmotic stabilizers. Secondly, in the regeneration of protoplasts, we explored the effects of various conditions on the regeneration of protoplasts, including different media and osmotic pressure. In addition, we found that citrate buffer with pH value around 3 dramatically increased the regeneration of protoplasts of A. cinnamomea, and provided a set of regeneration methodology for A. cinnamomea.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1590-1592
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• 2002

In this work the electrical characteristics of organic TFTs using organic insulator and flexible polyester substrate have been investigated. Pentacene and PVP(polyvinylphenol) are used as an active semiconducting layer and dielectric layer respectively. Pentacene was thermally evaporated in vacuum at a pressure of about $1{\times}10^{-6}$ Torr and at a deposition rate of $0.5{\AA}$/sec, and PVP was spin-coated. Aluminium and gold were used for gate and source/drain electrodes. 0.1mm thick flexible polyester substrate was used instead of glass or silicon wafer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.50-53
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• 1994

In this study. we report the properties of optically pumped stimulated emission at room temperature (RT) from column-III nitride semiconductors of GaN, GaInN, AlGaN/GaN double hetero-structure (DH) and AlGaN/GaInN DH which grown by low pressure metal-organic vapor phase epitaxy on sapphire substrate using an AIN buffer-layer. The peak wavelength of the stimulated emission at RT from AlGaN/GaN DH is 370nm and the threshold of excitation pumping power density (P$\_$th/) is about 89㎾/$\textrm{cm}^2$, and they from AlGaN/GaInN DH are 403nm and 130㎾/$\textrm{cm}^2$, respectively. The P$\_$th/ of AlGaN/GaN and AlGaN/GaInN DHs are lower than the bulk materials due to optical confinement within the active layers of GaN and GaInN. The optical gain and the polarization of stimulated emission characteristics are presented in this article.

• Journal of Food Hygiene and Safety
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• v.12 no.3
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• pp.195-199
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• 1997

For the purpose of isolation and screening of tyrosinase inhibitory activity from edible mushrooms, Pleurotus ostreatus, Auricularia auricula-Judae, Umbilicaria esculenta, Agaricus bisporus, Flammuline velutipes, Lentinus edodes, Ganoderma lucidum, and Coriouls versicolor were examined by tracing inhibitory activities against tyrosinase, utilizing L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate. Among the eight edible mushrooms tested, Umbilicaria esculenta showed potent enzyme inhibitory activities above 7804% against tyrosinase in ethylacetate (EtOAc) extracts. Ganoderma lucidum and Agaricus bisporus showed inhibitory activities of 67.3% and 51.5% in water extracts. EtOAc extracts of Umbilicaria esculenta was fractionated from silicagel column chromatography and one fraction showed the most inhibitory activity of 60.9%. The three bands (Rf=0.38, 0.27, 0.19) were isolated from preparative TLC of the fraction for purification and identified as mixtures of orsellinate, methyl orsellinate, methyl lecanorate, and methyl gyrophorate by high pressure liquid chromatography (HPLC), ultravisible spectrophotometer (UV), mass spectrophotometer (Mass), nuclear magnetic resonance spectrometer (NMR).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.629-633
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• 2006

We investigated a new longitudinal acceleration wave decomposition method in time domain. The proposed method separates up- and down-stream waves with an axial strain and axial acceleration measured at a single point on the transmission path. The advantages such as low computation load and easy implementation would be possible by developing time domain under the following assumptions; low frequency range, uniform cross sectional area and elastic wave propagation. We confirmed the feasibility and performance of the method through experiment using Split Hopkinson Pressure Bar (SHPB). The method can be effective in several applications, including active vibration control with wave view point, where real time wave decomposition is necessary.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.42-47
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• 2008

One of the main cases of the desertification impact is the negative contribution of human activities that worsen environment. There are historical facts of inability and excessive activities which destroyed the civilizations. The basic difference is only in the tempo and scales of civilization collapse. Human pressure was accumulated within the centuries and millennia due to the extremely active economic activities. But today it covers only the decades. Presently the process of desertification has a global scale. There are huge factors of Earth aridization as an increase of the quantity of C02 and atmospheric dust and bloom. This process related not only to the arid areas. Obviously a comprehensive approach of development of territories, particularly arid areas is very important. The use of the satellite information and technologies of remote sensing data processing can take a significant place for decision-makers for calculation and estimation of the environment impacts.

• Journal of the Korea Safety Management & Science
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• v.1 no.1
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• pp.183-195
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• 1999

Most of chemical plant are using toxic and dangerous materials, inflammable and poisonous. There are many accidental dangers by escaping of fire, explosive and poisonous materials in case of high temperature and pressure. The accidents lead to taking employer's and local people's life and environmental contamination. Therefore, 27 small-medium chemical plant, which size is 30 ∼ 200 employees out of safety management agent ill the area of A was selected in this study. The problems of safety management and several countermeasures at the chemical plants was indicated through the analyzed data. Prior to this analysis, top managers' concerns, equipment maintenance for the safety management are needed. For the future, calamity prevention countermeasures by industrial disaster analysis are needed and active safety management programs are investigated for the industrial disaster prevention and productivity enhancement at the chemical plant.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.80-92
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• 1998

A third-order simulation model of a Vuilleumier{VM) heat pump has been developed. This model takes into account the major losses such as the heat conduction losses through regenerators and displacers, the pumping losses and the wall-to-gas heat transfer losses in active volumes, in addition to the heat exchanger and regenerator losses. The working volume was divided into 12 control volumes and the conservation equations of mass and energy were applied to each control volume. Pressure drops were considered in regenerators only. Thermodynamic behavior of the working gas in a VM heat pump was investigated and effects of the major losses and operating conditions on the performance of a VM heat pump were shown.