• Microbiology and Biotechnology Letters
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• v.25 no.4
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• pp.408-413
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• 1997

It was studied in order to improve the yield of serrapeptase production in fermentation that organic nitrogen sources play important roles not only as inducer, repressor and activator, but also nitrogen sources. From the investigation of the effect of Na-caseinate on the induction of serrapeptase production, it was elucidated that real inducer was leucine and strong repressor was cysteine, which were produced through hydrolysis of proteins. Serrapeptase production was strongly induced by Na-caseinate in culture time 12 hrs, but was weakly induced before and after that time. Therefore fed batch culture where partial amount of Na-caseinate is added in 12 hrs, is better than batch culture where total amount of Na-caseinate is added at the beginning. Cysteine, methionine, MgSO$_{4}$, and so on, sulfur-containing materials, repressed the serrapeptase production. In the addition of mineral salts, chlorinated salts is better than sulfated salts because of sulfur repression. The synergic effect of soybean meal with Na-caseinate on the serrapeptase production resulted from Mn$^{2+}$ contained in soybean meal, of which the optimal concentration is 4 mM in enzyme production.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.2
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• pp.66-74
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• 1986

Rain samples were collected at 10 sites in the Seoul area during the period of August through November, 1985. THe concentrations of the major cations $(H^+, Ca^{++}, MG^{++}, Na^+, K^+, NH_4^+)$ and the major anions $(SO_4^=, NO_3^-, Cl^-)$ were measured to characterize the main sources of chemical ions in rainwater. Correlating concentrations of ions to pH, calculated coefficients ranged from 0.1485 to 0/4296. Sulfate shows the largest coefficient indicating that sulfate is more closely associated with hydrogen ion than other ions. This may suggest that sulfuric acid contributes more to the acidity of rainwater in Seoul. It appears that the major chemicals measured in rainwater are from the anthropogenic sources of air pollution. Predominant chemicals are acidic at the Guro-, the Sinseol-, the Yangnam-, and the Ssangmun-dong with sulfate being the most predominant. IT also indicates that alkaline substances resulting from soil and dust have a significant effect on pH values of rainwater by neutralizing actions. According to Granat-model analysis, it is estimated that the relative contributions to the rainwater acidity in Seoul are 84% from sulfuric acid, 8% from nitric acid and 8% from hydrochloric acid.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.250-255
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• 2005

Trichoderma inhamatum KSJ1, a filamentous fungus, isolated from rotten wood showed high ability to hydrolysis of cellulosic materials. Enzyme productivity by strain KSJ1 was high in the cultivation using carbon sources such as cellulosic materials and lignocellulosic wastes as rice straw and paper waste. In previous study peptone was one of optimum organic nitrogen sources in producing cellulases for saccharification of food wastes. However, it was too expensive using peptone as organic nitrogen source, so, in this study, soybean and yeast were applicated to substitute peptone. Yeast showed producing high enzyme activity, so it was estimated that yeast is available in producing cellulase using Trichoderma inhamatum KSJ1 at industrial Production.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.645-645
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• 2009

In many practical applications of the centrifugal fan, the impeller-diffuser interaction noise is considered as a main source of fan noise. The housing for an electric motor is also expected to play an important role on noise propagation because of its complicated configuration. This study investigates the impeller-diffuser interaction noise and its sources by computing three-dimensional, incompressible flow field of the centrifugal fan in motor housing. The effect of motor case on fan noise characteristic is then investigated using the Brinkman penalization method, while the noise source associated with impeller-diffuser interaction is mathematically modeled. It is found that the present methodology combined with mathematical description of noise source provides a fairly good agreement with the experimental results, indicating that the motor housing has significant effect on noise characteristics. Finally, aeroacoustic noise prediction for various impeller-diffuser blade count ratios is conducted for noise reduction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.73-76
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• 2005

Recently, the demand for the Floating, Production, Storage, and Offloading facility (FPSO) which has some economic and technical advantages, has increased in offshore oil production areas. FPSO vessel dose not have self-propulsion system, but has additional facilities for oil production and positioning system. Main noise sources such as gas turbines, compressors, and pumps, are located on top of the hull (Topside area). In general, the noise regulation for the offshore structure is severer than that of the cargo ship and acceptable noise limit of cabin is specified as 45 dB(A). This paper describes the noise characteristics and the countermeasures for FPSO Topside area through investigation of noise analysis and site measurement results. Proper countermeasures, considering the characteristics of sources and receiver spaces, were applied from the noise prediction and various measurement results. Finally, this ship was successfully delivered with excellent noise properties.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1590-1597
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• 2007

This paper deals with the noise source localization of the Korean High Speed Train (KTX) at the speed of 300 km/h. Using Microfonarray system and beamforming technology typical pass-by noise sources and their frequency characteristics are investigated. It is primarily aimed at investigating the location and characteristics of the high speed train emission. The results from the microphone array tests are also analyzed in relation to the remarks from analytic studies and experimental investigations on the high speed train that have been done with the intention of understanding the interior noise mechanism. The acoustical image shows the low frequency noise sources mainly at the position of the under part of the train at high speeds and the related source mechanism are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.58-64
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• 2001

An investigation of the TMR(Track Misregistration) requirements to achieve the capacity of 80GBytes／Platter in 7200rpm disk drive system is reported. This paper also gives an overview of the PES(Position Error Signal) characteristics in the 57,500TPI disk drive to estimate the required 95,000TPI-system PES. The TMR measured by PES are presented and decomposed in order to identify the portions and their contributions of the spindle-disk system vibration and HSA(Head-Stack-Assembly) system vibration respectively. A comprehensive review on the servo system is also presented to provide the practical limits of the modem servo architecture into TMR budget design. The decomposed PES energy distribution shows that the spindle-disk pack vibration is one of the top-ranking sources of the total TMR budget and its percentage contribution is about 50％ considering all the other TMR sources.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2184-2187
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• 2003

Quantizers for digital coding systems are usually optimized with respect to a model of the probability density function of the random variable to be quantized. Thus a mismatch of the quantizer relative to the actual statistics of the random variable may be unavoidable. This paper presents the results of an experimental investigation of mismatched quantizers. For the modeling of the source statistics, various types of the Weibull distribution are used, and the optimization of the quantizer is carried with respect to the minimum mean-square error (mse) criterion. The goal of this paper is to find an estimate formula for the mismatched quantizer on Weibull sources.

• Korean Journal of Microbiology
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• v.12 no.2
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• pp.69-69
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• 1974

This experiment was carried out to identify and to compare the radiosensitivities of bacteriz isolated from the sources of different radiation exposure histories. Among 10 strains isolated in this investigation, 4 strains of bacteria, Bacillus firmus, Bacillus brevis, Baciilus subtilis and Bacillus sphaericus were isolated from high and low radioactive sites simulaneously. Bacterial strains isolated from radioactive sources such as reactor and isotope production rooms were more resistant to irradiation than the microganisms from medical products and laboratories, however, there was no significance in radiosensitivity in the same species of bacteriz, even if they were isolated from different radiation exposure histories.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.6
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• pp.428-437
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• 2019

Analytical thermal models based on average convection heat transfer are frequently used for the design and selection of forced air-cooled plate fin heat sinks. In this paper, a convection heat transfer model within a ±10% margin of error was presented through experimental investigation. Five types of heat sinks with inlet widths of 1.7-6.8 mm were tested at 50-160 W heat sources to derive and verify the model. Causes of error between the experiment and analytical thermal model were analyzed and listed to design the heat sink. Using proposed method and the lists to be considered in the paper, a quick and accurate heat sink design of the power-conversion system is expected.