• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.143-150
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• 1976

A trial has been made to find out a new method of calculating the survival rate of a fish Population utilizing the length composition data and the characteristics of the frequency curve of the length which usually is normal distribution curve. In this paper, a stochastic method is introduced and applied to calculate the survival rate of yellow croaker caught by Korean trawlers in the Yellow Sea and the East China Sea in 1971. The results are as follows : Mean of survival rate 0.46089 Variance 0.03073 Standard deviation 0.17529 95 percent confidence interval 0.36040-0.56138.

• Journal of the Korean earth science society
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• v.38 no.7
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• pp.511-521
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• 2017

This study analyzes Two-dimensional video disdrometer (2DVD) data while summer 2011-2012 in Daegu region and compares with Marshall and Palmer (MP) distribution to find out statistical characteristics and characteristics variability about drop size distribution (DSD) of Daegu region. As the characterize DSD of Daegu region, this study uses single moment parameters such as rainfall intensity (R), reflectivity factor (Z) and double moment parameters such as generalized characteristics number concentration ($N{_0}^{\prime}$) and generalized characteristics diameter ($D{_m}^{\prime}$). Also, this study makes an assumption that DSD function can be expressed as general gamma distribution. The results of analysis show that DSD of Daegu region has ${\log}_{10}N{_0}^{\prime}=2.37$, $D{_m}^{\prime}=1.04mm$, and c =2.37, ${\mu}=0.39$ on average. When the assumption of MP distribution is used, these figures then end up with the different characteristics; ${\log}_{10}N{_0}^{\prime}=2.27$, $D{_m}^{\prime}=0.9mm$, c =1, ${\mu}=1$ on average. The differences indicate liquid water content (LWC) of Daegu distribution is generally larger than MP distribution at equal Z. Second, DSD shape of Daegu distribution is concave upward. Other important facts are the characteristics of Daegu distribution change when Z changes. DSD shape of Daegu region changes concave downward (c =2.05~2.55, ${\mu}=0.33{\sim}0.77$) to cubic function-like shape (c =3.0, ${\mu}=-0.13{\sim}-0.33$) at Z > 45 dBZ. 35 dBZ ${\leq}$ Z > 45 dBZ group of Daegu distribution has characteristics similar to maritime cluster of diverse climate DSD study. However, Z > 45 dBZ group of Daegu distribution has a difference from the cluster.

• Journal of Food Hygiene and Safety
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• v.22 no.4
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• pp.243-247
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• 2007

A selective analytical method of headspace-GC/MS has been applied to determine levels of benzene in beverages. Food samples were 85 including 2 fruit juices, 6 fruit beverages, 11 carbonated beverages, 55 mixed beverages, and 4 beverage concentrations, and 7 extracted beverages. For phase equilibration of headspace, sample was stirred at $40^{\circ}C$ for 30 min. The oven temperature was $60^{\circ}C$ and elevated to $180^{\circ}C$ at $15^{\circ}C/min$. The internal standard was benzene-d6. The identification was done by the selected target ions such as m/z 51, 77, and 78 and the confirmation was done by the response ratio of m/z 77 to m/z 78 between sample and standard. The overall recoveries were ranged from 91% to 101% and the limit of quantification was $1{\mu}g/kg$. The average level of benzene were $5{\mu}g/kg$ for fruit beverages, $2{\mu}g/kg$ for carbonated beverages, $7{\mu}g/kg$ for mixed beverages and $7{\mu}g/kg$ for extracted beverages.

• Analytical Science and Technology
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• v.21 no.4
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• pp.316-325
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• 2008

An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with flow injection-hydride generation system was used for the determination of trace arsenic in seawater sample. The accuracy in this method was verified by the analysis of certified reference materials (CRM) of seawater (CASS-4, NASS-5). The analytical results agreed with certified value within the range of uncertainty. The expanded uncertainties for CASS-4 and NASS-5 in this experiment were ranged from 6.2% to 6.8% obtained from repeated analyses of the CRMs (n=5). The detection limit of $As^+$ (m/z=74.9216) in this method was confirmed about 0.01 ug/kg. Linearity obtained from calibration curve of arsenic was excellent ($R^2=1$). The detection at $As^+$ (m/z=74.9216) and $AsO^+$ (m/z=90.9165) by using oxygen reaction gas in DRC mode was compared. Sensitivity at $AsO^+$ (m/z=90.9165) was decreased about 25-fold, but the analytical results are the same that at $As^+$ (m/z=74.9216).

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.165-175
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• 2024

Hydrogen is being touted as one of the energy sources to combat the climate change crisis. However, hydrogen can leak into enclosed spaces, rise to the ceiling, accumulate, and cause fires and explosions if it encounters an ignition source. In particular, ships that transport hydrogen or use it as a fuel comprise multiple enclosed spaces. Therefore, the dif usion characteristics within these spaces must be understood to ensure the safe use of hydrogen. The purpose of this study is to experimentally determine the diffusion characteristics of helium, which has similar properties to hydrogen, in a closed space on board a ship, and to determine the change in the oxygen concentration along the leakage direction as the air change per hour(ACH) increases to 25, 30, 35, 40, and 45 through CFD simulation. The study, results revealed that the oxygen concentration reduction rate was 2% for leakage in the -z direction and 1% for leakage in the +x and +z directions, and the ventilation time was 15 min 30 s for leakage in the -z direction, 7 min for leakage in the +x direction, and 9 min for leakage in the +z direction, showing that differences existed in the oxygen concentration and ventilation time depending on the leakage direction. In addition, no significant difference was observed in the rate of oxygen concentration reduction and ventilation time in all leakage directions from the ACH of 35 and above in the experimental space. Therefore, because the oxygen concentration and ventilation time were not improved by increasing the ACH, 35 was noted as the optimal ACH in this experimental environment.

• Honam Mathematical Journal
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• v.27 no.2
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• pp.301-315
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• 2005

Let $\{A_u,\;u=0,\;1,\;2,\;{\cdots}\}$ be a sequence of coefficient matrices such that ${\sum}_{u=0}^{\infty}{\parallel}A_u{\parallel}<{\infty}$ and ${\sum}_{u=0}^{\infty}\;A_u{\neq}O_{m{\times}m}$, where for any $m{\times}m(m{\geq}1)$, matrix $A=(a_{ij})$, ${\parallel}A{\parallel}={\sum}_{i=1}^m{\sum}_{j=1}^m{\mid}a_{ij}{\mid}$ and $O_{m{\times}m}$ denotes the $m{\times}m$ zero matrix. In this paper, a functional central limit theorem is derived for a stationary m-dimensional linear process ${\mathbb{X}}_t$ of the form ${\mathbb{X}_t}={\sum}_{u=0}^{\infty}A_u{\mathbb{Z}_{t-u}}$, where $\{\mathbb{Z}_t,\;t=0,\;{\pm}1,\;{\pm}2,\;{\cdots}\}$ is a stationary sequence of linearly positive quadrant dependent m-dimensional random vectors with $E({\mathbb{Z}_t})={{\mathbb{O}}$ and $E{\parallel}{\mathbb{Z}_t}{\parallel}^2<{\infty}$.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.32.1-32.1
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• 2015

The gradual infall of small dark matter halos onto larger ones has become a relatively straightforward aspect of the standard hierarchical formation paradigm. What happens to the baryons they contain, however, is less well understood. Of special relevance are the processes that regulate and ultimately suppress star formation in galaxies in the early universe. The z=1.5-2.5 epoch is then particularly interesting as a transition period when global star-formation in the universe starts peaking but also where the first ostensibly collapsed and virialized galaxy clusters appear, along with segregated galaxy populations. From a theoretical point of view, the mode of gas accretion in massive halos is also expected to change around this time, switching from a cold to a hot phase and affecting the build-up and evolution of the galaxies they host. A lot of effort has thus been devoted to the search for high-redshift structures, in particular galaxy clusters, through a variety of methods. However, as the limited area for which deep datasets are available remains relatively limited, only few massive z>1.5 structures have been found so far. Here I will instead discuss the regulation of star-formation in lower-mass, X-ray detected halos at z~2 and its implication for galaxy quenching at high redshift. As these smaller, group-size halos are vastly more abundant and structurally simpler than massive clusters, they allow for true statistical studies and offer a novel way to probe environmental effects in this transitional epoch.

• Microbiology and Biotechnology Letters
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• v.29 no.1
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• pp.12-17
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• 2001

Aspergil-lus coreanus NR-15 and Aspergilus oryzae NR-2-5 from traditional Korean Nuruk were selected as parental strains producing starch hydrolysis enzyme. Xll(Arginine-) mutant from A. coreanus NR 15-1 showed high glu-doamylase activity and total acid productivity. Z6(Adenine-) mutant from A. oryzae NR2-5 showed the highest $\alpha$-amylase activity. Therefore, both XII and Z6 mutants were selected and investigated for the optimal conditions of protoplast formation for protoplast fusion. Mixture of equal amount of cellulase and driselase(10mg/ml each) was the most effective as lytic enzymes. The optimal pH and temperature for protoplast formation were 5.0 and $30^{\circ}C$, respectively. The most effective reaction for protoplast formation time was 4 hours. The maximum of protoplst for- mation of Xll mutant and Z6 mutant were $6.54$\times$10^{7}$ protoplasts/ ml and $3.04$\times$10^{ 7}$ protoplasts/ml, and the regen-eration frequencies of the protoplasts were 11.3% and 11.6%, respectively. The size of the protoplasts from X11 and Z6 mutants were 3~6 $\mu\textrm{m}$ and 4~9$\mu\textrm{m}$, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.101-107
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• 1993

Zygosaccharomyces rouxii is a salt-tolerant yeast which plays an important role during the ripening stage of soy sauce fermentation. Z. rouxii used in the experiment could grow in YPD (1 % yeast extract, 2% peptone and 2% glucose, pH5.0) medium with 18% (w/v) NaCl, whereas Saccharomyces cerevisiae could only grow in YPD medium with less than 8% NaCl. In the presence of 15% NaCl, Z. rouxii accumulates a large amount of glycerol as a compatible solute within the cells in the exponential phase. It is a characteristic of salt-tolerant yeasts. From the chemical analyses on membrane lipid fluidity, the membrane structure of the cells grown in 15% NaCl was suggested to become more rigid and its fluidity was decreased to keep glycerol within the cells in response to surrounding medium with high concentrations of salt.

• Korean Journal of Food Science and Technology
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• v.40 no.5
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• pp.593-598
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• 2008

Differential display RT-PCR was used for screening the differentially expressed specific genes by Rhus verniciflua extract treatment to U937 cell, human leukemic monocyte. As a result, 19 clones differentially expressed were detected. Among the detected clones, one clone was confirmed to be over-expressed by R. verniciflua extract treatment in Northern blot analysis. Nucleotide sequence of the clone showed 100% homology with H2A histone family member Z gene. Therefore, it is concluded that the treatment of R. verniciflua extract to U937 cell specifically induces the expression of H2A.Z gene but its role should be elucidated by future works.