• Food Science and Preservation
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• 제9권3호
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• pp.271-276
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• 2002

To develop a wrapping film, which suppresses the microbial decay through the storage and prolongs the selflife of fruits and vegetables, the antimicrobial packaging films were prepared and applied to the preservation of strtwberries and cucumbers. Low density polyethylene(LDPE) film of 50㎛ thickness was faricated with 1% of Scutellariae baicalensis extract. The LDPE film impregnated with Scutellariae baicalensis extract showed antimicrobial activity on the disk test against Bacillus cereus, Escherchia coli and Fusarium sp.. The antimicrobial film changed the color and light transmittance, but did not affect heat shrinkage, mechanical tensile strength and wattability. Strawberries and cucumbers were separately wrapped with packaging films in the state of closely-adhered packaging as well as modified atmosphere packaging(MAP). The wrapped strawberries and cucumbers were stored for 21 days at 5$\^{C}$ and for 40 days at l0$\^{C}$, respectively. For the packaged strawberries and cucumbers at 5$\^{C}$ and 10$\^{C}$, the LDPE film impregnated with Scutellariae baicalensis extract showed the reduced growth of total aerobic bacteria, molds and yeasts and did not give any negative effect on other quality attributes during storage in comparison with conttrol film without any additive.

• Journal of Bio-Environment Control
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• 제20권3호
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• pp.233-240
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• 2011

We evaluated the changes of fruit quality factors and the incidence of physiological disorders during the periods of high temperature environment in 'Wonhwang' and 'Whasan' pears to determine appropriate harvest time for exportation. In 'Wonhwang' pears, the fruits harvested at 130 days after full bloom (DAFB) showed 31.3 and 17.6N of flesh firmness after 5 and 10 days after simulated marketing at $30^{\circ}C$, respectively, while those of the fruits harvested at 135 DAFB lowered to 16.7 or 6.9N, respectively. Whereas, 'Whasan' pear showed higher firmness during 14 days of high marketing condition than 'Wonhwang' pears which represented 30.4, 26.5 and 21.6N in the fruits harvested 145, 150 and 155 DAFB, respectively. Higher soluble solid contents and lower acidity values observed in the late harvested fruits in both cultivar along with increased marketing period at $30^{\circ}C$. Late harvested 'Wonhwang' pears showed higher respiration rate and ethylene production than early harvested ones, while those of 'Whasan' pears showed lower values regardless of fruit maturity which represented less than 50% of 'Wonhwang' pears. The incidence of physiological disorders such as internal browning, water soaking, flesh spot decay, core breakdown and pithiness appeared more severely in the fruits of 'Wonhwang' in accordance with the progress of high temperature marketing and fruit maturity. Whereas, those symptoms were occurred only after 14 days of prolonged marketing time in 'Whasan' pears. Consequently, it was needed to pay more attention to determine the ripeness when the fruits exported to the country with high temperature environment, especially in the fruits of 'Wonhwang' pears showing rapid quality loss and severe physiological disorders.

• Korean Journal of Veterinary Research
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• 제32권2호
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• pp.157-164
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• 1992

Changes in the both inward current and conductance of membrane by the fertilization were observed using the one microelectrode voltage clamp(or switch clamp) technique. Unfertilized eggs and both 1- and 2-cell stage eggs after fertilization were donated from the superovulated mouse (ICR, more than 6 weeks old) treated with PMSG(pregnant mare serum gonadotropin, Sigma) and HCG(human chorionic gonadotropin, Sigma) and naturally mated ones, respectively in this experiment. Membrane potential was held at -90mV and the voltage step was applied from -80mV to 50mV with interval of 10mV or 20mV for 300ms. since both of amplitudes and time courses in the membrane currents were various according to the states of cells and clamping condition, results were presented by their $averages{\pm}SEM$(standard mean error)and ratios or percentages. Inward currents began to appear in response to the step depolarization from -60mV and reached its maximum at -50mV. However, since the potential was not clamped evenly during the voltage step, current-voltage(I-V) relationship might be positively shifted 10 or 20mV. From the steady-state currents plotted in the I-V curve, outward rectification was markedly observed. Peak inward currents$(i_{in})$ at -50mV were $-0.62{\pm}0.23nA$(n=4),$-0.52{\pm}0.25nA$(n=5) and $-0.37{\pm}0.25nA$(n=6), in the 1-cell stage, 2-cell stage fertilized eggs and in the unfertilized eggs, respectively. Pure inward current (difference between steady-state and peak, $i_{in. pure}$) were $-1.01{\pm}0.23nA$, $-0.69{\pm}0.43nA$ and $-0.68{\pm}0.29nA$, respectively in the 1-cell stage fertilized eggs, unfertilized eggs and 2-cell stage fertilized eggs. These results suggested that the outward current in fertilized eggs of 2-cell stage was more increased than those in the unfertilized eggs. Pure inward currents in the all stages of eggs showed a similar fashion in the I-V relationship from -50mV to 50mV and reversal potential at 50mV. Time constant of inactivation$({\tau})$ in the inward current was decreased as the membrane potential was depolarized in the unfertilized and 2-cell stage eggs but in the 1-cell stage eggs t was not likely to be affected significantly. Slope conductances were 14.2nS, 8.9n5 and 7.7nS in the 1-cell, 2-cell stage fertilized eggs and the unfertilized eggs, respectively. Membranes between two cells within a zona pellucida seem to be electrical-connected in the 2-cell stage eggs from the observation made in the analysis for the electronic spread and decay to the current stimuli. Both of inward current and membrane conductance were increased after fertilization in the mouse eggs. Inward current seems to be carried by the same ion or through the same channels up to the 2-cell stage and ion that carried inward current was thought to play important function after fertilization in the mouse eggs.

• Progress in Medical Physics
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• 제25권1호
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• pp.31-36
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• 2014

We aimed to evaluate the dosimetric characteristics of reproducibility, linearity and dose dependence of optical stimulated luminance dosimeter (OSLD) in the Co-60 Gamma-rays and to analyze with a precedent study in field of the diagnostic radiography and radiotherapy. The reproducibility was 0.76% of the coefficient of variation, the homogeneity was within 1.5% of the coefficient of variation and OSLD had supra-linear response more than 3 Gy. So the correlation between dose and count was fitted by quadratic function. The count depletion by repeated reading was 0.04% per reading regardless of the irradiated dose. And the half time of decay curve according to the irradiated dose was 0.68 min. with 1 Gy, 1.04 min. with 5 Gy, and 1.10 min. with 10 Gy, respectively. In case of annealing for 30 min, the removal rate was 88% with 1 Gy, 90% with 5 Gy, and 92% with 10 Gy, respectively and 99% in case of annealing time for 4 hour. It is feasible to use OSLDs for dose evaluation in Co-60 Gamma-rays when considering the uncertainty on the procedure according to the irradiated dose.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• 제19권3호
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• pp.180-190
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• 2014

It has been customary to exclude top 10-20% of velocity profiles in the Acoustic Doppler Current Profiler (ADCP) measurement due to side lobe effects at the boundary. To better understand the mixing in the Yeongsan estuary, the freshwater advection speed (FAS) was recovered from highly contaminated ADCP data near the surface. The velocity profiles were measured by using ADCP at two stations in the Yeongsan estuary during August 2011: one was located in front of the Yeongsan estuarine dam and the other was deployed near Goha Island. The FAS was recovered from the ADCP data set by applying rigorous post-processing methods and compared with the sediment advection speed (SAS). The SAS was determined by the peak time difference of suspended sediment concentration between two stations in the channel, divided by the distance of two stations. The FAS and the SAS showed very similar value when the freshwater discharge was greater than $2.0{\times}10^7$ ton and the SAS was a bit greater when the freshwater discharge was smaller. Since the FAS was on average about 0.8 m/s greater than the velocity at 0.8 of water depth from the bottom, the net discharge, estimated with recovered FAS and integrated over water depth and tidal cycle, was directed seaward during the high discharge contrary to the onshore direction of the net discharge estimated with 0.8 of water depth from the bottom. Moreover, the velocity shear and Richardson number changed when the FAS was used. Thus, the importance of the true FAS is appreciated in the investigation of the surface layer stability. If currents, temperature and salinity were observed for longer time in the future, it could be possible to more accurately understand the formation and decay of stratification as well as the suspended sediment transport processes.

• Journal of Aquaculture
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• 제3권1호
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• pp.49-63
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• 1990

A population ecological study was carried out to estimate survival and growth rates, biomass, biological production and turnover ratio of cultured sea squirt, Halocynthia roretzi, by growth stages, using data from in situ culture experiment off Hansando in the southern part of Korea from February 1985 to July 1986. The squirt population followed an exponential decay function and the instantaneous coefficient of total mortality (Z) was estimated to be 0.0614 $month^{-1}$(Var (Z) = 0.000126). Growths in total weight and meat weight of squirts were expressed as linear functions during the period of culture experiment. The growth of squirts showed a negative correlation with the water temperature. The mean biomass per string ranged from 2.14 kg for March of the first year to 16.26 kg for March of the next year. The biological production per string was estimated to range from 3.28 kg for the first summer (June - July) to 6.46kg for the first late winter (February-March). The peak of turnover ratio occurred in the late winter (February-March) as 3.013 and the ratios sharply declined thereafter. Based on the results of this study, management implications for culturing sea squirts were also suggested. The optimum harvest time ($t_{mb}$) when the peak biomass in terms of total weight occurred was estimated to be late June of the second year, which corresponded to 16.7 months after the main hanging. However, the time when the peak biomass in terms of meat weight was occurred was early July of the second year. The maximum harvest biomass was 17.4 kg per string in terms of total weight and 6.3 kg per string in terms of meat weight. In conclusion, the process of culture should be conducted on the basis of the knowledge of population ecological theories as shown in this study.

• Journal of the Korean Society of Food Science and Nutrition
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• 제41권7호
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• pp.994-1001
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• 2012

Quality changes of pre-processed garlic, peeled and chopped, were analyzed during storage at $-18^{\circ}C$ or $2^{\circ}C$ for 30 days and at $20^{\circ}C$ for 3 days only for chopped garlic. As storage time increased, Hunter L values decreased and a, b values increased, indicating browning regardless of the pre-process type and storage temperature. Decay and sprouting rates of peeled garlic during storage at $2^{\circ}C$ significantly increased while those of peeled garlic were maintained during storage at $-18^{\circ}C$. Weight loss of peeled garlic during storage was greater at $-18^{\circ}C$ than at $2^{\circ}C$. Hardness of peeled garlic rapidly decreased by half from 1.04 kg to 0.58 kg by freezing, and it did not significantly change during the storage period. Viable numbers of total aerobic bacteria of peeled and chopped garlic did not significantly change during the storage period at $2^{\circ}C$ but were reduced at $-18^{\circ}C$. Total aerobic bacterial count of chopped garlic stored at $20^{\circ}C$ slightly increased during the storage period. Pyruvic acid content of chopped garlic was almost 2.5 times higher than that of peeled garlic at the initial stage (463.87 ${\mu}mol/g$ and 190.52 ${\mu}mol/g$, respectively). As storage time increased, pyruvic acid content of peeled garlic increased while that of chopped garlic decreased. These results indicate that pre-process type and storage temperature affected the quality changes of garlic during storage.

• Korean Journal of Agricultural and Forest Meteorology
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• 제10권4호
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• pp.158-166
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• 2008

The pumpkin fruit fly, Bactrocera depressa (Tephritidae: Diptera), is one of the most important pests in Cucurbitaceae plants. This study was conducted to investigate the basic ecology of B. depressa, and to develop a forecasting model for predicting the time of adult emergence in early season. In green pumpkin producing farms, the oviposition punctures caused by the oviposition of B. depressa occurred first between mid- and late July, peaked in late August, and then decreased in mid-September followed by disappearance of the symptoms in late September, during which oviposition activity of B. depressa is considered active. In full-ripened pumpkin producing farms, damaged fruits abruptly increased from early Auguest, because the decay of pumpkins caused by larval development began from that time. B. depressa produced a mean oviposition puncture of 2.2 per fruit and total 28.8-29.8 eggs per fruit. Adult emergence from overwintering pupae, which was monitored using a ground emergence trap, was first observed between mid- and late May, and peaked during late May to early June. The development times from overwintering pupae to adult emergence decreased with increasing temperature: 59.0 days at $15^{\circ}C$, 39.3 days at $20^{\circ}C$, 25.8 days at$25^{\circ}C$ and 21.4 days at $30^{\circ}C$. The pupae did not develop to adult at $35^{\circ}C$. The lower developmental threshold temperature was calculated as $6.8^{\circ}C$ by linear regression. The thermal constant was 482.3 degree-days. The non-linear model of Gaussian equation well explained the relationship between the development rate and temperature. The Weibull function provided a good fit for the distribution of development times of overwintering pupae. The predicted date of 50% adult emergence by a degree-day model showed one day deviation from the observed actual date. Also, the output estimated by rate summation model, which was consisted of the developmental model and the Weibull function, well pursued the actual pattern of cumulative frequency curve of B. depressa adult emergence. Consequently, it is expected that the present results could be used to establish the management strategy of B. depressa.

• Journal of Radiation Protection and Research
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• 제39권1호
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• pp.54-60
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• 2014

IAEA has employed various types of radiation detectors - HPGe, NaI, CZT - for accountancy of nuclear material. Among them, HPGe has been mainly used in verification activities required for high accuracy. Due to its essential cooling component(a liquid-nitrogen cooling or a mechanical cooling system), it is large and heavy and needs long cooling time before use. New hand-held portable HPGe has been developed to address such problems. This paper deals with results of performance evaluation test of the new hand-held portable HPGe prototype which was used during IAEA's inspection activities. Radioactive spectra obtained with the new portable HPGe showed different characteristics depending on types and enrichments of nuclear materials inspected. Also, Gamma-rays from daughter radioisotopes in the decay series of $^{235}U$ and $^{238}U$ and characteristic x-rays from uranium were able to be remarkably separated from other peaks in the spectra. A relative error of enrichment measured by the new portable HPGe was in the range of 9 to 27%. The enrichment measurement results didn't meet partially requirement of IAEA because of a small size of a radiation sensing material. This problem might be solved through a further study. This paper discusses how to determine enrichment of nuclear material as well as how to apply the new hand-held portable HPGe to safeguard inspection. There have been few papers to deal with IAEA inspection activity in Korea to verify accountancy of nuclear material in national nuclear facilities. This paper would contribute to analyzing results of safeguards inspection. Also, it is expected that things discussed about further improvement of a radiation detector would make contribution to development of a radiation detector in the related field.

• Analytical Science and Technology
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• 제25권6호
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• pp.447-459
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• 2012

In this study, the emission characteristics of volatile and odorant species released from salted meat product (Spam) was investigated as a function of time. Gas samples released from Spam samples were analyzed for volatile organic compounds (VOC) and sulfur compounds (RSC) at five different times for the elapsed (E) days of 0, 1, 3, 6, and 9 (E-0 to E-9) by GC/MS and GC/PFPD system, respectively. Results indicated that reduced sulfur, aldehyde, and ketone groups were the dominant odorants. Especially, hydrogen sulfide was the predominant in concentration and odor activity value (OAV) during the fresh stage. Its concentration was 1465 ${\mu}g/m^3$ (60.0% of the total mass) in E-0 and 455 ${\mu}g/m^3$ (28.0%) in E-1, while its OAV was 19.4 (78.3%: E-0) and 6.02 (41.7%: E-1). On the other hand, the concentration of acetone showed the maximum values in the decaying stage (E-3: 451 (43.2%), E-6: 369 (64.2%), and E-9: 1150 ${\mu}g/m^3$ (70.2%)). Furthermore, the concentration of 2,3-butanedione was also detected considerably from decaying sample (E-3: 17.6 (1.68%), E-6: 16.1 (2.80%), and E-9: 179 ${\mu}g/m^3$ (10.9%)). However, OAV of acetone was insignificant (<0.01%) in the decaying stage, while that of 2,3-butanedione was relatively high in the range of 1.14-11.6 (14.5-76.2% of ${\Sigma}OAV$). It thus confirmed that the major odorant groups generated from Spam samples changed with the progress of decay such as sulfur (fresh stage), aldehyde (intermediate stage), and ketone compounds (decaying stage).